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  #1  
Old 02-18-2011, 08:55 PM
danweseman danweseman is offline
 
Join Date: Mar 2009
Location: green cove springs fl
Posts: 77
Default RV-4 performance

Hi Guys I did some perfromance rund today with the -4 i jsut started flying.
Max Rpm on ground static 2200
WOT (wide open throttle) climb at 120 indicated 2700 rpm 5000ft DA timed 1510 fpm

DA of 8351
MP RPM Indicated mph GPS/TAS mph
18.5 2500 150 169

21 2700 165 181.5

24 (wot) 2900 181 196.5


1000ft DA

22 2500 160 169

23.5 2700 180 184

30 2950 201 204

This has a 0-360 and sensinich 72fm816-1-85 I dont know if its been repitched but the rpm seems a little high for 85 inches pitch. These seem below vans #s. I know alot comes into play here, the AC is not perfect but has all fairinmgs etc and has nothing that screams it should be low? Can anyone tell me how these #s compare. These were several runs averaged ,in smooth air. Density altutude was calculated on the 396 E6 function. Thanks Dan
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  #2  
Old 02-19-2011, 05:13 AM
pierre smith's Avatar
pierre smith pierre smith is offline
 
Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
Default Pretty good numbers Dan

You could use a little more pitch for a little gain in cruise but obviously, you'll give up some take-off and climb performance.

You can live with it as is but later on, a Catto two blade will show just how efficient they are.

Best,
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RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga

It's never skill or craftsmanship that completes airplanes, it's the will to do so,
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  #3  
Old 02-19-2011, 05:30 AM
Kevin Horton's Avatar
Kevin Horton Kevin Horton is offline
 
Join Date: Jan 2005
Location: Ottawa, Canada
Posts: 2,357
Default

The first step is to figure out whether the indicated values are accurate. Tachs and IAS can easily have significant errors.

Check the tach for accuracy. You should be able to borrow an optical tachometer locally from another builder or an A&P.

Check the static and pitot system for leaks, as they can affect IAS accuracy.

Check the ASI for instrument error using a water manometer. You could easily have 10 mph error. You can get a spreadsheet I wrote to convert between water manometer height and ASI reading here.

Conduct a static system error flight test. Static system position error could be more than 10 mph. You can read my notes on how to do this test and interpret the results here, or you can find the articles I wrote in Kitplanes a year or more ago.
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RV-8
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http://www.kilohotel.com/rv8/
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  #4  
Old 02-19-2011, 04:37 PM
Dennis_I's Avatar
Dennis_I Dennis_I is offline
 
Join Date: Dec 2005
Location: Sweden, 67" North
Posts: 68
Default

Sounds like u have a low RPM static and high RPM in flight... Our old RV4, had around 2400 Static and 2900 flat out at 185kts IAS sea level (150+HP engine)... I guess it is alot to do with prop and other factors...
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G?llivare, Sweden

Grew up with an RV-4, SE-XIO

Now: RV-8, Showplanes Fastback. #83218 Under construction, SE-XXO

Engine and avionic installation in progress
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  #5  
Old 02-19-2011, 06:08 PM
markscogg markscogg is offline
 
Join Date: Mar 2005
Location: Charlotte, NC
Posts: 306
Default No problem

I fly a -4 and it sounds fine to me. Leave it like it is and enjoy.
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Mark Scoggins
Charlotte, NC
RV-6 bought,flown and sold.
Rv-4 bought, flown and sold.
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