What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-6A performances

Barbeau

Barbeau

Member
HI RV6A owners
I just got a RV6A fitted with an O360 A1A with Lasar ignition system LC 1001-04, carb Precision MA-4-5.
propeller is a MT12-B/183-59.
Aircraft is a bit heavy ( 1208) due equipement.
I'm a bit upset regarding cruise performances. :mad:
3000 Fts engine 65% (22/2300) gives 140/145 Kts and 8.4 G/H
5500FTs engine 65% (22/2300) gives 145/150 Kts and 8.4 G/h
What about you?
It's a bit far from Van's data
 
Are you sure about your speeds? Are those TASs? Or IASs?

I have the O-360 in my -6, and I am 200 lbs lighter and 20 knots TAS faster...
 
More details

Bernard, you didn't mention whether or not you have installed wheelpants and landing gear fairings. We picked up over 16 MPH after we installed them. We also had a propeller designed specifically for maximum cruise speeds at 2750 RPM and got a TAS of 201 MPH at 7500'.

Best,
 
Barbeau said:
Aircraft is a bit heavy ( 1208) due equipement.
I'm a bit upset regarding cruise performances. :mad:
Click to expand...

Yes a bit heavy. 15-20% heavy. Heavy equals slower. [speed and weight are related through induced drag]
As Arlen points out you need to be comparing TAS. Go do the TAS flight test of flying several headings and use spreadsheet to calculate TAS.
Are you sure your IAS is showing anything close to CAS? My IAS is pretty close to CAS at 75 kts but reads low by 10 kts up at 150 kts.
I know nothing about your prop. That could be another place to check for numbers not match other 6As.
 
Morte details

Manu tanks
Speed are TAS calculated by EFIS (AFS 3500)
Whellpants and gear fairings are installed and perfectly fitted
CG range si between 74 / 75 AFT fois datum si within Van's data.
What about CG range regarding Cruise speed?
I did some test flights solo and grossweight and speed Gap si very low, les than 5 Kts
 
Barbeau said:
Manu tanks
Speed are TAS calculated by EFIS (AFS 3500)
Whellpants and gear fairings are installed and perfectly fitted
CG range si between 74 / 75 AFT fois datum si within Van's data.
What about CG range regarding Cruise speed?
I did some test flights solo and grossweight and speed Gap si very low, les than 5 Kts
Click to expand...

Greetings -

Weight makes very little difference in cruise speeds, probably not even the 5 knots you found (it could be other variables). CG similarly will have little affect, within reason.

I'd first roughly verify the indications/calculations the EFIS is making, and that is very easy to do. I would guess the AFS system has a well established calibration procedure. Short of that, do a four compass heading square path and use an on-line calculator to find TAS based on the four ground speeds. If the winds aloft are light, you can even get a reasonable approximation by simply averaging the four ground speeds.

I'd sort out the airspeed indicator/calculator first, then move on to other things.
 
Whaat??

Something is not right.

The difference in ambient pressure from 3000ft to 5500 ft is 26.82 in-hg to 24.435 in-hg which is 2.38 in difference. So - how did you obtain your numbers of 22 in MAP at both altitudes? Your testing should be at WOT and appropriately rich mixture. Without good test conditions airspeeds have no reference.
 
You must log in or register to reply here.
Back
Top