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teamgrumman(at)yahoo.com
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 Posted: Thu Feb 10, 2011 11:56 am Post subject: Engine down thrust angle |
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I'm doing an annual on a Tiger that came in with the engine visibly too far up. I measured the angle: .8 degrees up. The bottom mounts had two shims each. I removed one each of the bottom shims. The engine is now at .3 degrees up. RIght now, there is one shim on each mount.
Note: This plane just had a new engine installed. During the engine overhaul period, the engine mount was sent to Kosola Engine mounts for overhaul and painting. The installation also got all new -59 engine shock mounts.
The cowling is still below the spinner (i.e., spinner is higher than the cowling.) It could still use an extra shim in the top mounts; that would make two each on the top mounts, just like mine with the jaguar cowling.
[quote][b]
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n26390(at)AOL.COM
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| Posted: Thu Feb 10, 2011 12:06 pm Post subject: Engine down thrust angle |
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Gary: Aside from the mismatch between the cowling and spinner, what is the effect on performance/groundspeed of too much angle up or down?
Thanks,
Roger Rucker
AA5A '78 HWO
--
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teamgrumman(at)yahoo.com
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| Posted: Thu Feb 10, 2011 12:38 pm Post subject: Engine down thrust angle |
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From what I've found on the internet, a down thrust angle is preferred over an up or zero thrust angle. With a down thrust angle, there is less requirement for pitch changes with throttle changes. I have also noticed there is less requirement for elevator down (nose down) with an engine down thrust angle. That in itself should lessen overall drag.
From: "n26390(at)AOL.COM" <n26390(at)AOL.COM>
To: teamgrumman-list(at)matronics.com
Sent: Thu, February 10, 2011 12:03:57 PM
Subject: Re: Engine down thrust angle
Gary: Aside from the mismatch between the cowling and spinner, what is the effect on performance/groundspeed of too much angle up or down?
Thanks,
Roger Rucker
AA5A '78 HWO
--
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flyadive(at)gmail.com
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| Posted: Thu Feb 10, 2011 5:08 pm Post subject: Engine down thrust angle |
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Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
- There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
- There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- When the power is cut the plane will start to balloon just a little.. Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
- If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
[quote][b]
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teamgrumman(at)yahoo.com
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| Posted: Fri Feb 11, 2011 10:49 am Post subject: Engine down thrust angle |
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Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
[quote][b]
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flyadive(at)gmail.com
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| Posted: Sat Feb 12, 2011 7:46 am Post subject: Engine down thrust angle |
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Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
| Quote: | Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
|
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or  Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
[quote]
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
| Quote: |
st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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[b]
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flyv35b(at)minetfiber.com
Guest
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| Posted: Sat Feb 12, 2011 8:58 am Post subject: Engine down thrust angle |
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"AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust."
Another way of looking at this is the wing has a center of pressure, Cp, where the lift vector is located. This changes with AOA and is located aft of the CG in all the planes we typically fly. This Cp creates a pitching moment which is nose down and needs to be counteracted by a down force from the tail to keep the plane in balance. That's why as the CG moves aft the pitching moment decreases and there is less down force required by the tail and therefore less tail drag. To this equation you have a thrust and a drag vector and to the extent that they don't coincide you have a change in this moment about the CG which could add or subtract from the pitching moment (low wing vs high wing, engine thrust angle).
I have heard of a 2 place Grumman that had the horizontal stabilizer angle of incidence "changed" to reduce the tail drag and apparently had a sizeable increase in speed, probably at the expense of stability.
Cliff
[quote] ---
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teamgrumman(at)yahoo.com
Guest
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| Posted: Sat Feb 12, 2011 10:25 am Post subject: Engine down thrust angle |
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whatever
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
| Quote: | Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
|
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
| Quote: |
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
|
[quote][b]
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david555(at)cox.net
Guest
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| Posted: Sat Feb 12, 2011 10:45 am Post subject: Engine down thrust angle |
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Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
To: teamgrumman-list(at)matronics.com
Subject: Re: Engine down thrust angle
whatever
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
| Quote: |
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
|
012
345678901234567890
[quote][b]
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teamgrumman(at)yahoo.com
Guest
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| Posted: Sat Feb 12, 2011 9:16 pm Post subject: Engine down thrust angle |
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www.AuCountry.com
I just finished a major reorganization of the web site. Over 100 hours was spent on the Restoration page alone.
From: David Boone <david555(at)cox.net>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 10:43:17 AM
Subject: RE: Engine down thrust angle
Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
To: teamgrumman-list(at)matronics.com
Subject: Re: Engine down thrust angle
whatever
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
| Quote: |
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
|
012
345678901234567890
1
[quote][b]
| | - The Matronics TeamGrumman-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?TeamGrumman-List |
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quinn_tom(at)tqiinc.com
Guest
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| Posted: Sun Feb 13, 2011 4:04 am Post subject: Engine down thrust angle |
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|
Gary, excellent job on the website!
Tom Quinn
249RR
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Sunday, February 13, 2011 12:13 AM
To: teamgrumman-list(at)matronics.com
Subject: Re: Engine down thrust angle
www.AuCountry.com
I just finished a major reorganization of the web site. Over 100 hours was spent on the Restoration page alone.
From: David Boone <david555(at)cox.net>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 10:43:17 AM
Subject: RE: Engine down thrust angle
Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
To: teamgrumman-list(at)matronics.com
Subject: Re: Engine down thrust angle
whatever
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
| Quote: |
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
| Quote: | | st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List |
| Quote: | | tp://forums.matronics.com_blank">http://www.matronics.com/contribution |
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| Posted: Sun Feb 13, 2011 10:37 am Post subject: Engine down thrust angle |
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Thanks.
From: Tom Quinn <quinn_tom(at)tqiinc.com>
To: teamgrumman-list(at)matronics.com
Sent: Sun, February 13, 2011 4:01:30 AM
Subject: RE: Engine down thrust angle
Gary, excellent job on the website!
Tom Quinn
249RR
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Sunday, February 13, 2011 12:13 AM
To: teamgrumman-list(at)matronics.com
Subject: Re: Engine down thrust angle
www.AuCountry.com
I just finished a major reorganization of the web site. Over 100 hours was spent on the Restoration page alone.
From: David Boone <david555(at)cox.net>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 10:43:17 AM
Subject: RE: Engine down thrust angle
Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server(at)matronics.com [mailto:owner-teamgrumman-list-server(at)matronics.com] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
To: teamgrumman-list(at)matronics.com
Subject: Re: Engine down thrust angle
whatever
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
| Quote: |
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
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http://www.matronics.com/Navigator?TeamGrumman-List |
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flyadive(at)gmail.com
Guest
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| Posted: Mon Feb 14, 2011 6:06 am Post subject: Engine down thrust angle |
|
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Hey Gary...
Took ANOTHER in my many LQQKs at your web site.... IT POPS!
Very nice job.
Barry
On Sun, Feb 13, 2011 at 1:30 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
[quote]Thanks.
From: Tom Quinn <quinn_tom(at)tqiinc.com (quinn_tom(at)tqiinc.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Sun, February 13, 2011 4:01:30 AM
Subject: RE: Engine down thrust angle
Gary, excellent job on the website!
Tom Quinn
249RR
From: owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com) [mailto:owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com)] On Behalf Of Gary Vogt
Sent: Sunday, February 13, 2011 12:13 AM
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Subject: Re: Engine down thrust angle
www.AuCountry.com
I just finished a major reorganization of the web site. Over 100 hours was spent on the Restoration page alone.
From: David Boone <david555(at)cox.net (david555(at)cox.net)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Sat, February 12, 2011 10:43:17 AM
Subject: RE: Engine down thrust angle
Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com) [mailto:owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com)] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Subject: Re: Engine down thrust angle
whatever
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors
| | - The Matronics TeamGrumman-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?TeamGrumman-List |
|
|
|
| Back to top |
|
|
teamgrumman(at)yahoo.com
Guest
|
| Posted: Mon Feb 14, 2011 11:04 am Post subject: Engine down thrust angle |
|
|
thanks Barry
From: FLYaDIVE <flyadive(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Mon, February 14, 2011 6:03:48 AM
Subject: Re: Engine down thrust angle
Hey Gary...
Took ANOTHER in my many LQQKs at your web site.... IT POPS!
Very nice job.
Barry
On Sun, Feb 13, 2011 at 1:30 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
| Quote: | Thanks.
From: Tom Quinn <quinn_tom(at)tqiinc.com (quinn_tom(at)tqiinc.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Sun, February 13, 2011 4:01:30 AM
Subject: RE: Engine down thrust angle
Gary, excellent job on the website!
Tom Quinn
249RR
From: owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com) [mailto:owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com)] On Behalf Of Gary Vogt
Sent: Sunday, February 13, 2011 12:13 AM
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Subject: Re: Engine down thrust angle
www.AuCountry.com
I just finished a major reorganization of the web site. Over 100 hours was spent on the Restoration page alone.
From: David Boone <david555(at)cox.net (david555(at)cox.net)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Sat, February 12, 2011 10:43:17 AM
Subject: RE: Engine down thrust angle
Gary, do you have a website. Thanks David
From: owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com) [mailto:owner-teamgrumman-list-server(at)matronics.com (owner-teamgrumman-list-server(at)matronics.com)] On Behalf Of Gary Vogt
Sent: Saturday, February 12, 2011 1:20 PM
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Subject: Re: Engine down thrust angle
whatever
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Sat, February 12, 2011 7:31:04 AM
Subject: Re: Engine down thrust angle
Hello Gary:
I'm smiling here, your response is also interesting and
I will place my response within the body of your/our email.
As a quick note, on some of your statements you are saying the same thing as I.
And Gary... Thank you for the due respect, but it is perfectly alright for you to question me and even disagree - But, we don't disagree.
OK... Let's read on...
On Fri, Feb 11, 2011 at 1:46 PM, Gary Vogt <teamgrumman(at)yahoo.com (teamgrumman(at)yahoo.com)> wrote:
Hi Barry,
with all due respect, what you say does make some sense, but . . .
There is a down thrust on the elevator to keep the nose up and that is created by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose on a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder," if you want to go fast, the horizontal needs to be flying. I.e., the elevator needs to be lifting the plane. Or, at a bare minimum, provide a minimum down force. That is why the plane is faster with aft CG loading.
[Barry] - On many planes - I do not have Grumman's build procedure or the maintainance manual in front of me ... But you will find the horizontal stabilizer to be in a NEGATIVE angle. This creates a down thrust on the tail.
NOW! GC is all important but just for S&G's lets say the CG is in the center and let's also think of the plane as a See-Saw (teeter-totter).
And let's also look back at our tail feathers as we have the plane trimmed out for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area) is pointing slightly down. Elevator trailing edge up. This varies on our planes. The AA5 and AA1 w/ O-320 sure shows this. On the AA5-A & B with the bigger Horz Stab does not show this as much or at all.
AND as you said - "the elevator needs to be lifting the plane" ... But how does it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so there is a balance to the See-Saw. Counter balancing the weight of the engine and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of the main wing. Well in this balance situation, this angle (AoI) is there to lift the 'weight' at the CG.
And since we are flying S&L the Angle of Attack does not come into play. We are keeping things simple so we do not have to deal with adding and subtracting vectors. We can simply say the AoI is over coming the weight of the plane and lifting directly at the CG.
You said: "at a bare minimum, provide a minimum down force."
So we agree there is a down force - - - I called it a down thrust on the Horz Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
| Quote: |
- - - - With a down thrust angle, less force is needed on the tail to hold the tail down.
|
[Barry] - TRUE.... That is what I said. We are saying the same thing.
| Quote: |
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
- - - - Down thrust of the engine? What are you talking about here? The elevator down thrust, from the classical point of view, balances the lift from the wing about the aircraft CG.
|
[Barry] - I don't think you mean to question is there such a thing as engine down thrust. I'm missing why the question.
Where you mention the elevator down thrust balancing the lift of the wing... What about the weight of the engine. You have a See-Saw that balances on the CG. But there is also the weight of the engine and thrust angle of the engine. There is more than just lift of the wings.
| Quote: |
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree. I flew it after. I didn't notice any difference. It still has .3 degrees up thrust angle. The plane flies fine.
- - - - In a landing configuration, there is so little thrust from the engine compared to the aircraft angle of attack as to make it a non-issue.
- - - - I do agree that with and engine with several degrees of up angle thrust, it would be like landing down-wind.
|
[Barry] - We AGREE here also. Obvously the small changes you are working with are not enough to be noticed or Upset the apple cart
| Quote: |
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with down thrust on the engine. There is a web site for remote control plane builders that outlines the process for determining the optimum down thrust to keep the plane stable during throttle changes.
- - - - With an increase in power from cruise condition, the increase in effective angle-of-attack due to increase speed, has the effect of lifting the nose of the plane about the CG. With a down thrust angle, the plane feels more stable.
- - - - Likewise, with a decrease in power from a full power condition, the plane will want to drop it's nose. With a down thrust angle, that trim has already been trimmed in and the effect is less diversion from horizontal flight; i.e., a more stable airplane.
|
[Barry] - EXACTLY.... We agree once again.
As a R/C note.... YUP... Been flying those things since 1970 and U-kee way back in 1958... Yup, I'm that old.
AND why do they have so much down thrust to the engine? The HUGE ... HP to Weight Ratio. Most R/C planes have a Zero Angle of Incidence (AoI) to the main wing as well as the Horz Stab. (Of course some do have a positive angle)
I use to do Quicky 500 Racing. The plane weighed 3.5 Lbs exactly had a .40 CuIn engine that developed 0.75 to 1.0 HP. <-- I do not recall the advertised HP, I'm just using a S.W.A.G. and more than likely it was higher... Especially my re-worked engines
Nope - I did not have a NELSON 40... there you are talking close to 2 HP
So wing loading was only: 0.99 Lbs per SqFt with a Wt to HP of only: 0.21 HP per Lb
While my AA5 is 0.068 HP per Lb
And a AA5-B is 0.075 HP per Lb.
That is a 3.08:1 ratio GREATER with the R/C... WOW!
BTW - Ever fly a tail heavy plane? What happened when you cut power?
YIKES! Almost lost a a Gorgeous Kasos 60 <-- Pattern Plane
| Quote: |
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
- - - - see above. I agree.
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
- - - - see above. I agree.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
|
[Barry] - So Gary --- I believe we agree... Just a different ways of explaining it.
Barry
| Quote: |
From: FLYaDIVE <flyadive(at)gmail.com (flyadive(at)gmail.com)>
To: teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)
Sent: Thu, February 10, 2011 5:06:11 PM
Subject: Re: Engine down thrust angle
Gary & Team:
From my experienced down thrust is a good thing ... IN MODERATION.
There is a down thrust on the elevator to keep the nose up and that is created by the air flow.
There is a lateral pivot point which balances down thrust of the elevator against down thrust of the engine.
AND this is a BIG ONE - It is much easier to land a plane with down-thrust to an engine than one with up-thrust. With up-thrust you have to fly the plane onto the runway. SO, what happens with ZERO Thrust?
There is more of a neutral feel and WHICH I PREFER - And when power is cut there is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of down elevator is used to keep the plane S&L. So what happens with Down-Thrust?
When the power is cut the plane will start to balloon just a little... Most people will not even notice it. And in many cases you will already be trimmed very close to best glide SO there is less work to do when setting up for a landing.
NOW! ALL this information is dependent on HOW MUCH thrust we are talking about.
If the feel is that noticeable you have some major thrust errors to correct.
Barry
"Chop'd Liver"
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