Matronics Email Lists :: View topic - Losing rpm on takeoff

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Losing rpm on takeoff
Goto page 1, 2 Next

Matronics Email Lists Forum Index -> RotaxEngines-List

View previous topic :: View next topic

Author Message

occom

Joined: 26 Aug 2006
Posts: 404

Posted: Tue Nov 30, 2010 1:50 pm Post subject: Losing rpm on takeoff

Looking for ideas here. My test pilot says he is  losing about 500 rpm upon becoming airborne. Has low rpm all during climb and is  doubtful of full power on cruise. EGT's appear fine, although he was not riveted  on the gauge having a few other things to watch. 

  

 I checked fuel flow and the function of the vacuum  fuel pump to be ok. I also had a look at the plugs and they look a little dark  but not wet and certainly not lean. 

  

 I did a one minute run at full power on the ground  with no loss of rpm, it pulls a little over 6200 static, EGT's run up to around  1100 but drop off quickly with only a little pull back on the throttle and  normally run around 1000-1025 on a Westach gauge. 

  

 Currently reviewing a my documentation for ideas.  Right now I'm leaning toward doubting the tach. 

  

 Engine has 82 hours and was recently checked  out by a service center.  

  

 Dave Goddard

KitFox IV 1050 / 582 /  Warp

   [quote][b]

gpabruce(at)gmail.com
Guest

Posted: Tue Nov 30, 2010 2:42 pm Post subject: Losing rpm on takeoff

You might try adapting a simple manifold pressure guage (an automotive vaccuum guage in other words) so you can get some additional data, another point of reference. Record your aircraft attitude/angle of attack  (improvise a cheap protractor level mounted inside the cockpit) and speed by GPS (not to be confused with altitude) although you may want to note altitude as well. 

   

 It is possible that your prop is running more efficiently "at speed" and he RPM drop is a factor of power to airspeed. It maybe a good thing. You cannot necessarily depend on your airspeed indicator to make this assumption, I would use a GPS to backup my airspeed. The manifold pressure is an indication of power. The higher the manifold pressure, the higher the power output.

   

 I have to go but will write more later.

  

 Bruce 

  

 run around 1000-1025 on a Westach gauge. 

  [quote]   

 Currently reviewing a my documentation for ideas. Right now I'm leaning toward doubting the tach. 

  

 Engine has 82 hours and was recently checked out by a service center.  

  

 Dave Goddard

KitFox IV 1050 / 582 / Warp

 	  Quote: 	
		  



"_blank">www.aeroelectric.com

.com/" target="_blank">www.buildersbooks.com

="_blank">www.homebuilthelp.com

_blank">http://www.matronics.com/contribution

ist" target="_blank">http://www.matronics.com/Navigator?RotaxEngines-List

ttp://forums.matronics.com

	


[b]

grahamsingleton(at)btinte
Guest

Posted: Tue Nov 30, 2010 2:53 pm Post subject: Losing rpm on takeoff

Warp Drive props dp this. A fixed pitch WDrive on a Europa will always giove an rpm drop during take off and early climb. It sounds to me that you ae also a bit coarse.

Graham

From: Dave G <occom(at)ns.sympatico.ca>

To: kitfox-list(at)matronics.com; rotaxengines-list(at)matronics.com

Sent: Tuesday, 30 November, 2010 21:46:59

Subject: Losing rpm on takeoff

        Looking for ideas here. My test pilot says he is  losing about 500 rpm upon becoming airborne. Has low rpm all during climb and is  doubtful of full power on cruise. EGT's appear fine, although he was not riveted  on the gauge having a few other things to watch. 

 I checked fuel flow and the function of the vacuum  fuel pump to be ok. I also had a look at the plugs and they look a little dark  but not wet and certainly not lean. 

 I did a one minute run at full power on the ground  with no loss of rpm, it pulls a little over 6200 static, EGT's run up to around  1100 but drop off quickly with only a little pull back on the throttle and  normally run around 1000-1025 on a Westach gauge. 

 Currently reviewing a my documentation for ideas.  Right now I'm leaning toward doubting the tach. 

 Engine has 82 hours and was recently checked  out by a service center.  

 Dave Goddard

KitFox IV 1050 / 582 /  Warp

   [quote]www.aeroelectric.comhttp://www.matronics.com/corget="_blank" href="http://www.matronics.com/Navigator?RotaxEngines-Lis target="_blank" href="http://forums.matronics.com">http://forums.matro===================[b]

occom

Joined: 26 Aug 2006
Posts: 404

Posted: Tue Nov 30, 2010 3:03 pm Post subject: Losing rpm on takeoff

Engine is a Rotax 582 two stroke, Though the sig  would indicate that but wanted to make sure respondents understood.  

 [quote]   ---

flyadive(at)gmail.com
Guest

Posted: Tue Nov 30, 2010 3:25 pm Post subject: Losing rpm on takeoff

Dave:



Not Enough Information...

YES you DEFINITELY should lose RPM when you pick the nose UP for rotation and begin your climb.

Start with a STATIC reading - Record RPM

 Then a high speed taxi and and the RPM should go UP - You are unloading the prop. - Record RPM

Take Off and climb to 2500' AGL fly S&L - Record RPM & IAS & OAT

Establish S&L - From the S&L do a climb at 500 FPM, climb to 3500' AGL  - Record RPM during climb.  YES - It should be less than S&L.  How long did it take for the climb? <-- Checking VSI

 



WHAT IS A VACUUM FUEL PUMP?

What gas are you running?  The plugs should be gray to light brown.

I do not trust an analog Westach Gage.

1100 F for EGT sounds a bit low for full power - This with the color you report for your plugs indicate you are running rich.  BUT!  This will vary with EGT Probe location. 

 



Do the IAS's fall in the correct ball park?

Hook up a simple automotive clip on tack to verify planes Tach accuracy.  Or use a PhotoTach for a comparison. <--- R/C guys use them - Borrow one.

 



Barry

  [quote][b]

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Tue Nov 30, 2010 3:45 pm Post subject: Losing rpm on takeoff

On 11/30/2010 1:46 PM, Dave G wrote:  	  Quote: 	
		  Looking for ideas here. My test pilot says he is losing about 500 rpm upon becoming airborne. Has low rpm all during climb and is doubtful of full power on cruise. EGT's appear fine, although he was not riveted on the gauge having a few other things to watch. 	
 

 Dave,

     I once over-pitched my prop and had a hilarious outcome. I had great static RPM off the stops but about 50' down the runway RPM started to drop. By the time I got to 500' RPM was down to 5800 and by the time I got to 1000' it plummeted to about 4700. Needless to say I wasn't going anywhere. Best I can figure was that the prop was stalled static and hooked up as I started moving forward. Now how that works with my 912 brethren who use 2 1/2d more pitch for the same prop spinning the other way I can't figure. I only know that when I reduced pitch 1/2 degree everything worked "normally" with no drop on takeoff.

 

 Guy Buchanan

 Kitfox IV-1200 / 582-C / Warp 3cs / 500 hrs    [quote][b]

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Nov 30, 2010 4:00 pm Post subject: Re: Losing rpm on takeoff

 	  Quote: 	
		  Looking for ideas here. My test pilot says he is  losing about 500 rpm upon becoming airborne. Has low rpm all during climb and is  doubtful of full power on cruise. EGT's appear fine, although he was not riveted  on the gauge having a few other things to watch. 

  

 I checked fuel flow and the function of the vacuum  fuel pump to be ok. I also had a look at the plugs and they look a little dark  but not wet and certainly not lean. 

  

 I did a one minute run at full power on the ground  with no loss of rpm, it pulls a little over 6200 static, EGT's run up to around  1100 but drop off quickly with only a little pull back on the throttle and  normally run around 1000-1025 on a Westach gauge. 

  

 Currently reviewing a my documentation for ideas.  Right now I'm leaning toward doubting the tach. 

  

 Engine has 82 hours and was recently checked  out by a service center.  

  

 Dave Goddard

KitFox IV 1050 / 582 /  Warp

  	


Dave,   Your static RPM sounds in the right range 6000 t0 6300 IF your tach is correct - Get a Tiny  tach  if you do not have one. 



EGT gauge is only for reference not for actual temps but it might read accurate - WHO KNOWS !! Plugs will tell you  what is going on inside.

At cruise 5800 to 6000 RPM  plugs should be med to light brown. MEd or darker is too rich or too much pitch.  You should be be using NGK BR8ES. If you do not have the right plugs order some from Bob Robertson when you order the tiny tach  1-866-418-4164.

If your EGT are correct you should see 1100 to 1200 rpm in cruise no colder. Your EGT are calibrated for 70 F  right now the temps are about 20 to 30 F outside do you are reading 50 F  higher than it really is.



Cheers



Your needle clip should be in the 3 rd notch from the top but changing to the bottom notch once temps are below 0 C  ( 32 F)  for the winter.

_________________
Realtime Kitfox movies to separate the internet chatter from the truth
http://www.youtube.com/user/kitfoxflyer
Hundreds of Kitfox Movies
Most viewed Kitfox on youtube
Most popular on youtube
Highest rated on youtube

occom

Joined: 26 Aug 2006
Posts: 404

Posted: Tue Nov 30, 2010 4:09 pm Post subject: Losing rpm on takeoff

Well, once again, it is a two stroke. Not a 912.  two stroke would melt running EGT's typical of a 912. 

  

 I should note that I am aware of the extreme  feelings of some persons regarding two strokes, no need to repeat them here  thanks. 

  

 I got a couple of emails that say a warp prop will  load up more as you begin to move/ climb. I had understood load to be max at  static load, apparently this is not true? 

 Static is as I wrote, 6200 

 You wrote :  YES you DEFINITELY should lose RPM when you pick the nose UP for  rotation and begin your climb.

  

 Are you indicating that climb RPM will be less than static RPM? This is  apparently what I am experiencing.



  

 Vacuum fuel pump is a little misleading, the two  strokes run a crankcase port to a mechanical pump that uses vacuum/pressure from  the engine to pump fuel. I expect the two stroke guys knew what I meant.  

 [quote]   ---

flyadive(at)gmail.com
Guest

Posted: Tue Nov 30, 2010 4:17 pm Post subject: Losing rpm on takeoff

Guy:



Your data does not make sense.  If you were over pitch and started to roll you would be unloading your prop and the RPM would Go UP.  ANYTIME you start your take off roll the RPM goes UP.  If not... Then something else is wrong.

 Even if you were under pitched there would be a increase in RPM ... Not as much as if you had the correct pitch or over pitched... But it would still go UP.

You had something else wrong and fixed it by mistake - not realizing it.

 



Barry



[quote] Dave,

     I once over-pitched my prop and had a hilarious outcome. I had great static RPM off the stops but about 50' down the runway RPM started to drop. By the time I got to 500' RPM was down to 5800 and by the time I got to 1000' it plummeted to about 4700. Needless to say I wasn't going anywhere. Best I can figure was that the prop was stalled static and hooked up as I started moving forward. Now how that works with my 912 brethren who use 2 1/2d more pitch for the same prop spinning the other way I can't figure. I only know that when I reduced pitch 1/2 degree everything worked "normally" with no drop on takeoff.

 

 Guy Buchanan

 Kitfox IV-1200 / 582-C / Warp 3cs / 500 hrs     	  Quote: 	
		  	




[b]

flyadive(at)gmail.com
Guest

Posted: Tue Nov 30, 2010 4:44 pm Post subject: Losing rpm on takeoff

Dave:



Two Stroke engines use gas to cool more than four stroke engines.  They also have more raw gas being pumped over board in this cooling process.  The EGT will also be dependent on the location of the EGT Probe.  

 



Flexible Props will increase in pitch as the RPM drops.  This is why some may say they load up.

BUT!  Any time you point the nose UP the RPM will DROP.  It is simple physics.  And it does NOT matter what prop is on the plane.  It is Pitch and Load that cause the RPM to drop.

 



YES - Climb RPM will ALWAYS be less that S&L ... BUT - Do not use the term STATIC.  When the plane is flying the prop is unloaded less than when it is in a STATIC state.  Unless you are doing something like a departure stall and are full power and stalling at the same time.

 



Vacuum Fuel Pump is TOTALLY misleading and the wrong terminological... You are using Crank Case Pressure to move the fuel.

You can't have it both ways... It is PRESSURE not "vacuum/pressure'.

 Check for leaks in the Crank Case Pressure lines - Just in case you are not getting good fuel flow.



 

Fly the test outline I sent and then we will have information to make a real diagnosis.

 Barry

PS:

I also do not understand why your Test Pilot does not understand the princeables of flight.  Is he qualified or just so excited to fly?

  



On Tue, Nov 30, 2010 at 7:05 PM, Dave G <occom(at)ns.sympatico.ca (occom(at)ns.sympatico.ca)> wrote:

[quote]        Well, once again, it is a two stroke. Not a 912.  two stroke would melt running EGT's typical of a 912. 

  

 I should note that I am aware of the extreme  feelings of some persons regarding two strokes, no need to repeat them here  thanks. 

  

 I got a couple of emails that say a warp prop will  load up more as you begin to move/ climb. I had understood load to be max at  static load, apparently this is not true? 

 Static is as I wrote, 6200 

 You wrote :  YES you DEFINITELY should lose RPM when you pick the nose UP for  rotation and begin your climb.

  

 

Are you indicating that climb RPM will be less than static RPM? This is  apparently what I am experiencing.



  

 Vacuum fuel pump is a little misleading, the two  strokes run a crankcase port to a mechanical pump that uses vacuum/pressure from  the engine to pump fuel. I expect the two stroke guys knew what I meant.  

 [quote]   ---

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Tue Nov 30, 2010 5:30 pm Post subject: Re: Losing rpm on takeoff

 	  occom wrote: 	
		  Well, once again, it is a two stroke. Not a 912.  two stroke would melt running EGT's typical of a 912. 

  

 I should note that I am aware of the extreme  feelings of some persons regarding two strokes, no need to repeat them here  thanks. 

  

 I got a couple of emails that say a warp prop will  load up more as you begin to move/ climb. I had understood load to be max at  static load, apparently this is not true? 

 Static is as I wrote, 6200 

  

	




This will for sure be the case if it's a taper tip prop (dont know about the square tip). The way it works is the tips are essentially stalled at static airflows, but then they unstall as the airflow picks up through the prop disk. 



This happens for quite a range of airspeeds, which is how the prop manages to work almost like a constant-speed and gives a very consistent load over a wide range of speeds.



So, unlike with a conventional prop, the static rpm almost doesn't tell you anything. The first time I ran a taper tip on my 912 I didn't understand how it worked. I added pitch until I got about 5200 static, but when I went out to do a taxi test, the rpm dropped and dropped and dropped as I picked up speed just like the other poster said. By the time I was at rotate speed (about 60mph or so) I was down to about 4700 rpm!



So basically you have to pitch for correct rpms when moving (i.e. just bumping up against redline at max level speed and wide open, or for desired rpm at your desired airspeed, i.e. 6300 or so for the 582).



The taper tip has a really wide speed range so you can get it just about spot on by pitching for redline at max. level and you're pretty much done at that point. 



LS

_________________
LS
Titan II SS

occom

Joined: 26 Aug 2006
Posts: 404

Posted: Tue Nov 30, 2010 5:33 pm Post subject: Losing rpm on takeoff

Barry I understand you like to be a stickler  for terminology, I'm not and it's unlikely that I'll change. If you knew what  pump I was referring to, mission accomplished as far as I'm concerned. I know  how it works and how to rebuild it, I mentioned it only to make people aware  that it had been checked and it's fine, moving on. 

  

 My test pilot is quite accomplished  thanks.

  

 Now, I truly do appreciate the help, but I do not  understand why you are tossing in stuff I did not mention, I'm sure that  everyone understands that when you climb you are loading the engine and rpm may  drop somewhat, this is not what I am asking and at this point I am not concerned  about S&L.

  

 Lets get down to basics. I tied the aircraft to a  big heavy thing that does not move... on the ground. I then started and warmed  up the engine, at full throttle in this state RPM is 6200 and the EGT's are  around 1100. When the aircraft is flown, rpm drop below the rpm I experience  while the aircraft is stationary on the ground tied to a big, heavy thing. I  previously called this static RPM, it seemed easier and I understood the term to  be commonly used.  

  

 I am asking if anyone can help me to understand why  a moving aircraft might experience a lower RPM than one tied to a big heavy  thing on the ground as this strikes me as contrary to my previous  understanding.  This is the only question I wish to address at this  point. I did not know that propellers slow down when they are tilted up, I  expect this is not what you meant.  

  

 Once again, I appreciate the attempt to assist. If  I do not use the language the way you wish, please try to  adapt.  Thanks. 

  

 ---

occom

Joined: 26 Aug 2006
Posts: 404

Posted: Tue Nov 30, 2010 5:57 pm Post subject: Losing rpm on takeoff

Thanks Lucien, this sounds quite close to what I am experiencing. It is 

indeed a taper tip, my previous was a GSC which behaved much differently.

---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Nov 30, 2010 7:14 pm Post subject: Losing rpm on takeoff

Dave:

 

Barry is probably right in his description of the testing regimen but I agree with you about getting back to basics.  For me Getting back to basics means making sure your tach is accurate.  I’m willing to bet dollars to doughnuts that your tachometer is reading way too high.  If it is, thinning the pitch will allow your engine to develop more torque.... hence more power for takeoff.

 

No doubt you will be actively working on this so keep us informed.

 

Noel

 

From: owner-rotaxengines-list-server(at)matronics.com [mailto:owner-rotaxengines-list-server(at)matronics.com] On Behalf Of Dave G

Sent: November 30, 2010 9:58 PM

To: rotaxengines-list(at)matronics.com

Subject: Re: Losing rpm on takeoff

 

Barry I understand you like to be a stickler for terminology, I'm not and it's unlikely that I'll change. If you knew what pump I was referring to, mission accomplished as far as I'm concerned. I know how it works and how to rebuild it, I mentioned it only to make people aware that it had been checked and it's fine, moving on. 



 



My test pilot is quite accomplished thanks.



 



Now, I truly do appreciate the help, but I do not understand why you are tossing in stuff I did not mention, I'm sure that everyone understands that when you climb you are loading the engine and rpm may drop somewhat, this is not what I am asking and at this point I am not concerned about S&L.



 



Lets get down to basics. I tied the aircraft to a big heavy thing that does not move... on the ground. I then started and warmed up the engine, at full throttle in this state RPM is 6200 and the EGT's are around 1100. When the aircraft is flown, rpm drop below the rpm I experience while the aircraft is stationary on the ground tied to a big, heavy thing. I previously called this static RPM, it seemed easier and I understood the term to be commonly used.  



 



I am asking if anyone can help me to understand why a moving aircraft might experience a lower RPM than one tied to a big heavy thing on the ground as this strikes me as contrary to my previous understanding.  This is the only question I wish to address at this point. I did not know that propellers slow down when they are tilted up, I expect this is not what you meant.  



 



Once again, I appreciate the attempt to assist. If I do not use the language the way you wish, please try to adapt.  Thanks. 



 



---

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Wed Dec 01, 2010 1:46 am Post subject: Re: Losing rpm on takeoff

 	  Quote: 	
		  I am asking if anyone can help me to understand why a moving aircraft might experience a lower RPM than one tied to a big heavy thing on the ground as this strikes me as contrary to my previous understanding. This is the only question I wish to address at this point. I did not know that propellers slow down when they are tilted up, I expect this is not what you meant. 	




Dave - if your tach is too high then you could be falling off the power curve and to do that you would be doing that around 4800 to 5200 rpm .

eg if tach is reading static 6200 rpm then it actually might be only 5000 -5500?



How was take off performance ? You Iv should be off the ground in under 200 feet  with no wind.

occom

Joined: 26 Aug 2006
Posts: 404

Posted: Wed Dec 01, 2010 2:33 am Post subject: Losing rpm on takeoff

We simply haven't got to the point of beginning any  testing regimen, we are attempting to get past this single issue. A lot of  information on other things is just noise at this point. 

  

 The tach will be checked of course, it was accurate  on my old engine. 

  

  

 ---

davidjoyce(at)doctors.org
Guest

Posted: Wed Dec 01, 2010 2:44 am Post subject: Losing rpm on takeoff

I have come across the phenomenon of the prop being stalled at low forward 

speed but unstalling as the plane gathers speed, with  the unstalled prop 

offering more resistance and therefore slowing rpm. For some props it is 

said to be potentially damaging to run them at full power in a stalled 

state.

Regards, David Joyce

---

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Wed Dec 01, 2010 4:58 am Post subject: Re: Losing rpm on takeoff

 	  Float Flyr wrote: 	
		  

I am asking if anyone can help me to understand why a moving aircraft might experience a lower RPM than one tied to a big heavy thing on the ground as this strikes me as contrary to my previous understanding.  This is the only question I wish to address at this point. I did not know that propellers slow down when they are tilted up, I expect this is not what you meant.  



--- 	




Like I said, this is a difference in design of the taper tip WD over a conventional prop, so you can't really use the same methods to set the initial pitch. 



No, you're not imagining anything, the taper tip will spin up faster with the plane tied to a stick than when accelerating down the runway where it'll actually load up and slow down. The static load is unreliable because the tips are stalled, so it' s almost useless to try to set a particular static RPM.



What I did on mine to set the intial pitch was to pitch for the right rpm's on takeoff/climb. This required a few high speed taxis to confirm the engine was turning the right rpm (about 5300 to start with) once I got to takeoff speed. 



Then, once I got it to where I wasn't dangerously overloaded or underloaded to actually fly the plane, I went up and verified rpms in flight. On mine (68" 3 blade on a 912ULS, titan tornado) I settled on around 5400 rpm at Vy (about 65mph). The interesting thing was the rpm would hardly vary from 5400 rpm all the way up to about 80mph! That's the constant speed -ish action of the taper tip - it doesn't "unwind" as much as a conventional prop.



Unfortunately I had to go to a different prop because of an incurable harmonic vibration problem with my particular plane, but while I did have the WD on it the performance was absolutely spectacular, especially at higher speeds. 



So that'd be my suggestion as to how to proceed at this point - get a good rpm at takeoff speeds so you can actually go fly the plane around. Then fine-adjust the pitch from there.



LS

_________________
LS
Titan II SS

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Wed Dec 01, 2010 5:12 am Post subject: Re: Losing rpm on takeoff

 	  occom wrote: 	
		  Thanks Lucien, this sounds quite close to what I am experiencing. It is 

indeed a taper tip, my previous was a GSC which behaved much differently.

--- 	




Right, the GSC is a more conventional prop, with a more constant blade AOA as you go out to the ends. So most if not all of the blade stalls at the same AOA. 



The powerfin I had to replace my WD with is a conventional design too so the static RPM tends to be a reliable measure. It also spins up and unloads in the expected way as the airflow through the prop disk increases. 



Nothing can outclimb my powerfin but the WD taper tip has by far the best performance over the widest speed range I've ever seen on a prop. So if yours is a faster plane, you won't ever want to fly anything else once you get the pitch set right. 



It's particularly good for a 2-stroke on a faster plane since it provides more of a constant load on the engine which is what you need for a steady EGT. I ran a 68" taper tip on my Kolb Firestar II which had a 503 on it. I never had to monkey with anything to keep the EGT's steady between climb and cruise regimes. It loaded the motor very well throughout the (albeit limited) speed range of the plane....

LS

_________________
LS
Titan II SS

Dick Maddux

Joined: 24 Jun 2008
Posts: 516
Location: Milton, Fl

Posted: Wed Dec 01, 2010 5:34 am Post subject: Losing rpm on takeoff

>>     This will for sure be the case if it's a taper tip prop (dont know about the square

      tip). The way it works is the tips are essentially stalled at static airflows,

      but then they unstall as the airflow picks up through the prop disk. 

      

      This happens for quite a range of airspeeds, which is how the prop manages to work

      almost like a constant-speed and gives a very consistent load over a wide

      range of speeds.

      

      So the static rpm almost doesn't tell you anything. The first time I ran a taper

      tip on my 912 I didn't understand how it worked. I added pitch until I got about

      5200 static, but when I went out to do a taxi test, the rpm dropped and dropped

      and dropped as I picked up speed just like the other poster said. By the

      time I was at rotate speed (about 60mph or so) I was down to about 4700 rpm!

      

      So basically you have to pitch for correct rpms when moving (i.e. just bumping

      up against redline at max level speed and wide open, or for desired rpm at your

      desired airspeed, i.e. 6300 or so for the 582).

      

      The taper tip has a really wide speed range so you can get it just about spot on

      by pitching for redline at max. level and you're pretty much done at that point.

      

      

      LS  <<

  

 Interesting LS ,my Warp taper tip has never done that in the 2 years it has been on my aircraft. I get 5200 WOT on take off roll and on climbout it accelerates to about 5400 rpm on my 80 hp 912.

  I am now using a Kiev and it too never drops. It,however stays at 5200 rpm thru take off and climb. I have been watching these numbers very closely comparing the two propellers.I am staying with the Kiev as it is lighter and much,much smoother.

                                                     Dick Maddux

                                                      912 UL 

                                                       

 [quote][b]

Display posts from previous:

	Matronics Email Lists Forum Index -> RotaxEngines-List	All times are GMT - 8 Hours Goto page 1, 2 Next
Page 1 of 2

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum