GOLDPILOT(at)AOL.COM
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 Posted: Tue Feb 15, 2011 3:24 pm Post subject: TeamGrumman-List Digest: 2 Msgs - 02/14/11 |
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Just forwarding everything like everybody else does!
Nice Grumman web site. Good job.
In a message dated 2/15/2011 12:07:00 A.M. Pacific Standard Time, teamgrumman-list(at)matronics.com writes:
| Quote: | *
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TeamGrumman-List Digest Archive
---
Total Messages Posted Mon 02/14/11: 2
----------------------------------------------------------
Today's Message Index:
----------------------
1. 06:06 AM - Re: Engine down thrust angle (FLYaDIVE)
2. 11:04 AM - Re: Engine down thrust angle (Gary Vogt)
________________________________ Message 1 _____________________________________
Time: 06:06:42 AM PST US
Subject: Re: Engine down thrust angle
From: FLYaDIVE <flyadive(at)gmail.com>
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> wrote:
| Quote: | 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> 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.
- - - - 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.
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.
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
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
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
------------------------------
*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"
* *
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* *
*st" target="_blank">http://www.matronics.com/Navigator?TeamGrumman-List*
* *
*tp://forums.matronics.com*
*_blank">http://www.matronics.com/contribution*
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*http://www.matronics.com/Navigator?TeamGrumman-List*
*http://forums.matronics.com*
*http://www.matronics.com/contribution*
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|
________________________________ Message 2 _____________________________________
Time: 11:04:25 AM PST US
From: Gary Vogt <teamgrumman(at)yahoo.com>
Subject: Re: Engine down thrust angle
thanks Barry
________________________________
From: FLYaDIVE <flyadive(at)gmail.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> wrote:
Thanks.
| Quote: |
________________________________
|
From: Tom Quinn <quinn_tom(at)tqiinc.com>
| Quote: |
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.
________________________________
|
| Quote: | 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
________________________________
|
| Quote: | 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
|
| Quote: | 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> 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
|
| Quote: | by the air flow. (HUH?)
- - - - In flight, the elevator is rarely in a position to raise the nose
on
|
| Quote: | a plane that wants to go fast. Disregarding the drawing in "Stick and Rudder,"
|
| Quote: | if you want to go fast, the horizontal needs to be flying. I.e., the elevator
|
| Quote: | needs to be lifting the plane. Or, at a bare minimum, provide a minimum down
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | for S&L.
You may see that the leading edge of the elevator (Counter Balance weight area)
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | it lift the plane? Not by LIFTING the TAIL... But by pushing the tail down so
|
| Quote: | there is a balance to the See-Saw. Counter balancing the weight of the engine
|
| Quote: | and in some... Down Thrust.
You are probably thinking right about now of the Angle of Incessants (AoI) of
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | Stab.
Force and Thrust are interchangeable as a vector description.
We are both saying the same thing.
> - - - - With a down thrust angle, less force is needed on the tail to hold
|
| Quote: | >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
|
| Quote: | elevator down thrust, from the classical point of view, balances the lift from
|
| Quote: | 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
|
| Quote: | engine than one with up-thrust. With up-thrust you have to fly the plane onto
|
| Quote: | the runway. SO, what happens with ZERO Thrust?
- - - - I flew the subjects plane before lowering the engine 1/2 degree.
I
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | is only a small pitch change.
- - - - Modelers that build free flight and remote control always build with
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | nose of the plane about the CG. With a down thrust angle, the plane feels more
|
| Quote: | stable.
- - - - Likewise, with a decrease in power from a full power condition, the
|
| Quote: | 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;
|
| Quote: | 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
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?
| Quote: | - - - - 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
|
| Quote: | 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.
|
| Quote: | 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: |
________________________________
|
| Quote: | 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
|
| Quote: | 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
|
| Quote: | engine than one with up-thrust. With up-thrust you have to fly the plane onto
|
| Quote: | 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
|
| Quote: | is only a small pitch change.
With Up-Thrust when the power in cut the plane wants to DIVE - Since a lot of
|
| Quote: | 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
|
| Quote: | 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.
|
Use ilities ay - MATRONICS WEB FORUMS - List Contribution Web Site p;
|
[quote][b]
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