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  #51  
Old 11-26-2022, 11:57 AM
Gustavo Aulara Gustavo Aulara is offline
 
Join Date: Nov 2022
Location: Torino, Italy
Posts: 24
Default

Quote:
Originally Posted by Gustavo Aulara View Post
Some good news about my RV-3: today I had a ferry flight to another airport where a friend of mine is going to check the battery charging system. The last two weeks the few hours dedicated to my airplane were to remove the carbon looking film, at this purpose I removed the wheel and leg fairings, so I flew WITHOUT fairings. Temperature was 10C and QNH 1018mb, level flight at 1050 ft no wind. I surprisingly got 2600 rpm and 153 KTS of TAS! This number makes sense, I guess the root cause for the low speed was probably the wrong angle of attack of the fairings.
In the incoming weeks the RV-3 will be painted, I will add the wood or aluminum stiffeners on the landing gear legs and spend time to properly mount the fairings.
All the checks on carburetor and rigging did not show problems, still need to check mag timing. I bought a very cheap laser tachometer on Amazon, may be too cheap while it didn't work...
Most probably this will be the new color scheme:
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  #52  
Old 11-26-2022, 02:05 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
Posts: 2,941
Default Speed

I would think there is something very inconsistent in measuring speed and power. Possibly some kind of engine issue. There is know way that gear leg fairings can cause that kind of speed difference. The misalignment would need to be in the range of 10 degrees.
The pressure recovery wheel pants are considerably faster than the original Vans wheel pants. On my 0 320 Wittman Tailwind no wheel pants 162 knots, Sam James wheel pants 170 knots.
Gear leg fairings should be at least 5 knots.
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  #53  
Old 11-26-2022, 06:33 PM
blaplante blaplante is offline
 
Join Date: Jan 2010
Location: Southern California
Posts: 553
Default

Quote:
Originally Posted by Gustavo Aulara View Post
Some good news about my RV-3: today I had a ferry flight to another airport where a friend of mine is going to check the battery charging system. The last two weeks the few hours dedicated to my airplane were to remove the carbon looking film, at this purpose I removed the wheel and leg fairings, so I flew WITHOUT fairings. Temperature was 10C and QNH 1018mb, level flight at 1050 ft no wind. I surprisingly got 2600 rpm and 153 KTS of TAS!
very odd. Typically badly aligned wheel and leg fairings will cause issues with trim - ball out of center, etc. Hard to imagine them being so far off as to slow you down.

Things to consider:
  • How much fuel in this test versus before?
  • Engine leaned for best power in all your tests?
  • Baggage weight changes?
  • Wide open throttle?

Best speed will be at about 7500' at wide open throttle. Wide open throttle at lower altitude will be over 75% power (and not recommended for continuous use).

Keep us posted!
__________________
RV6A in phase 2 as of April 2016
Donation made Dec 2022
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  #54  
Old 11-26-2022, 09:31 PM
FireMedic_2009 FireMedic_2009 is offline
 
Join Date: Nov 2016
Location: Tampa, FL
Posts: 324
Default My numbers are in TAS

My numbers are in TAS on pg4 post #31
__________________
RV-6A IO-320 FP sold
RV3B O-320 160hp
Donated 2018 and continue annually

Last edited by FireMedic_2009 : 11-26-2022 at 10:12 PM.
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  #55  
Old 11-27-2022, 11:38 AM
Gustavo Aulara Gustavo Aulara is offline
 
Join Date: Nov 2022
Location: Torino, Italy
Posts: 24
Default

Quote:
Originally Posted by blaplante View Post
very odd. Typically badly aligned wheel and leg fairings will cause issues with trim - ball out of center, etc. Hard to imagine them being so far off as to slow you down.

Things to consider:
  • How much fuel in this test versus before?
  • Engine leaned for best power in all your tests?
  • Baggage weight changes?
  • Wide open throttle?

Best speed will be at about 7500' at wide open throttle. Wide open throttle at lower altitude will be over 75% power (and not recommended for continuous use).

Keep us posted!
Many thanks to all for the valuable help!
Yesterday I had that short flight just to move the RV from my home to an airport, 20NM away.
I previously checked if carburetor and fuel could be full opened and it was the case, then I removed the fairings for painting prepairing.
With my friend Gianluca that is a good avionic guy, we agreed to move the RV to his shopfloor to check the charging system and the other instruments.
Immediately after take off I realized that the RV wanted to run, achieving a good acceleration to 140Kts TAS while climbing. I was full throttle and fuel.
I leveled to 1200 ft approx., and I noticed a speed above 150 Kts that was a good news by itself. I also noticed that the trim tab placed on the rudder was putting the ball on the opposite side (I spent some time 14 days ago to center the ball without feet on controls), over correcting the initial defect (ball on the right). At that time I tried to level, set the rpm at 2600 (it would have done something more at full throttle) and read the speed at full rich: the speed was stable at 153KTS, max throttle gave me 159 KTS TAS.
Outside temperature was 10deg Celsius.
Since the last flight I also removed 100% of the carbon look plastic film that might have a role in drad augmentation, but I am convinced that the main effect is due to fairings removal.
Now I am going to paint the RV and this will take some weeks, at the same time the panel (avionics) will be re-wired.
I will also apply the leg stiffeners to eliminate shimmy and check once again the rigging.
Fortunately I discovered that close to me there are 2 RV-3 owners, so we have planned to fly toghether to compare parameters and performances.
In the avionics rewiring we will add a map instrument to understand something about power, and set the fuel flow sender to realistic values.
I will keep you all informed about the results, many thanks again to all of you who are supporting this project.
Gustavo
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  #56  
Old 11-27-2022, 12:19 PM
blaplante blaplante is offline
 
Join Date: Jan 2010
Location: Southern California
Posts: 553
Default More thoughts

I think I understand that you had:
Adjusted the rudder trim tab to center the ball.
Then, Removed the wheel pants,
and now the ball is (significantly?) out of center.

This means the wheel pants were not aligned. That caused yaw. To correct the yaw the rudder needed more trim to fight the wheel pants. That is drag. So there is a partial answer to the slow speed problem.

I don't know that you have for engine monitoring to accurately lean, but generally full rich will not give full power. Some amount of leaning is usually needed. Especially if you test at 7500' as I suggested.

Full fuel in my RV-6A will reduce my speed by a few knots.
__________________
RV6A in phase 2 as of April 2016
Donation made Dec 2022
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  #57  
Old 11-27-2022, 12:26 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 8,041
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glad it is going in the right direction. However, I am struggling to see how you picked up 30 knots by REMOVING the fairings. Not an Aero engineer, but wonder how that is possible without those fairings installed so poorly that no one could miss it.

Can't help but wonder if that was coincidence and something else changed. If it were me, I would be looking for that change, as it may revert back to what it was.

Larry
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N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 11-27-2022 at 12:31 PM.
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  #58  
Old 11-27-2022, 05:34 PM
Lufthans's Avatar
Lufthans Lufthans is offline
 
Join Date: Dec 2017
Location: Hilversum, The Netherlands
Posts: 240
Default

Quote:
Originally Posted by Gustavo Aulara View Post
Fortunately I discovered that close to me there are 2 RV-3 owners, so we have planned to fly toghether to compare parameters and performances.

Gustavo
Congratulations on finding some speed Gustavo!

Is Giulio, the owner of PH-URZ, one of these two? If not, I might have a third RV3 owner for you . I believe he lives somewhere north-west of Milano.

(And if he in fact IS one of the two, then please say hello from me)

Good luck with the paint job and avionics
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Hans Teijgeler
Hilversum, The Netherlands


PH-KLT Resurrecting an RV-3B, with Subaru EJ25 STi
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PH-MGA Jodel DR1050; Built, with Subaru EJ25
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PH-EIL RV-4; Imported and upgraded for friend. Sadly crashed
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