V speeds for a RV-6

[Leonard_Smith_nz]

All,

I'm starting to do some advance preparation work for my test flying and would like to get a 'feel' for the RV6 V speeds. I've looked online at a few POH and noted the numbers shown below.

I appreciate that test flying is all about how YOUR aircraft performs, but as a starting point, do these look in the ballpark?

Vr 55 kts (63 mph)
Vx 65 kts (75 mph)
Vy 75 kts (86 mph)
Vcc 100 kts (115 mph) (Cruise climb)
Va 115 kts (132 mph)
Vno 155 kts (178 mph)
Vne 180 kts (207 mph)
Vs 48 kts (55 mph)
Vso 43 kts (49 mph)
Vfe 90 kts (103 mph)
Vgs 70 kts (80 mph)

BTW, is there a recognized abbreviation for 'cruise climb'?

Regards,
Leonard (RV6 in New Zealand)

Engine: TMX-O360 180hp
FP Prop: Sensenich 85"

[Brian130]

I've seen Vcc on Cirrus spec sheets. Works for me.

[Kyle Boatright]

The Vx and Vy numbers depend tremendously on whether you have a fixed pitch or a constant speed prop.

I have a fairly aggressive fixed pitch cruise prop and my Vx is probably 80 knots and Vy is over 100 knots. Below those speeds, the engine simply isn't turning fast enough.

At heavy weights, the Vx and Vy are even higher.

[N162RV]

I have seen 75mph as a Vx in a few POH on this forum but not sure what engine/prop combo that was for. I have a 160hp / FP cruise prop -6A and at 85mph the nose is rediculously high and can't imagine 75mph. What airframe, engine /prop combo do you have and what are you V speed?

[pierre smith]

Hi Leonard,
Our best rate of climb is around 135 MPH for 1700 FPM and cruise climbs at 150-160 MPH still yield over 1000 FPM. We weigh 1065 Lbs with a FP Catto three blade.

Regards,

[terrykohler]

Leonard:
Some years ago the CAFE foundation conducted a comprehensive flight test on an RV6A. Typically, these tests are carried out with calibrated test equipment rather than builder installed/non-calibrated hardware and cover a wide range of performance characteristics. You can see this and other RV reports on:
www.cafefoundation.org
Click on "Research and Publications", then on CAFE APRs.
Good luck with your testing.
Terry

[n468ac]

Here's ours...

AIRSPEED LIMITATIONS
SPEED KIAS REMARKS
VNE Never Exceed Speed 182 Kts Do not exceed this speed in any operations.
VNO Maximum Structural Cruising Speed 156 Kts Exceed this speed only in smooth air.
VA Maneuvering Speed 115 Kts Do not make full control movements above this speed. Full elevator deflection will result in a 6g load at this speed.
VFE Maximum Flap Extended Speed 96 ?20 deg
87 - Full Do not exceed this speed with flaps down
Vy Best Rate of Climb 103 Kts
Vx Best Angle of Climb 65 Kts
Vs Stall Speed Clean 47 Kts
Vso Stall Speed Landing Configuration 43 Kts

[tin man]

A lot of good baseline speeds, how about BEST GLIDE?
Tom

[wv4i]

The numbers found on Van's website and in the manual are the ones to use, and verify. There will be some variation depending on weight, CG, but they are close. I would concentrate, initially, more on ensuring the accuracy of the airplane's airspeed indicator, as best as possible, via ground and flight test.

Maybe it's early, but I don't think Vy is affected by prop type. Vy is an airspeed, and is primarily determined by the wing, secondarily by weight and operating CG, while the resultant RATE of climb will certainly vary with HP/propeller. Right?

[Kevin Horton]

Originally Posted by wv4i

Maybe it's early, but I don't think Vy is affected by prop type. Vy is an airspeed, and is primarily determined by the wing, secondarily by weight and operating CG, while the resultant RATE of climb will certainly vary with HP/propeller. Right?

It's early.

The rate of climb is determined by weight and excess power. Excess power is the power available minus the power required to maintain level flight at that speed, weight, etc. The power required for level flight at a given weight won't be affected by prop type. But, the power available will. For a given engine at full throttle, the power available at a given altitude and temperature varies with rpm and prop efficiency.

If you have a constant speed prop, the engine can develop max rpm at any speed. So Vy will probably be very close to the speed where the minimum power is required for level flight (variation in prop efficiency with speed will probably make Vy very slightly faster than the speed for min power required). But if you have a fixed pitch prop, the rpm (and hence the power) will be higher the faster you fly. So Vy will be a faster speed than for a constant speed prop.