I have a question on Flight Test V-numbers...

[noelf]

I have about 8 hours on my new Superior engine, have remained within the airport environment so far, and now am ready to embark on establishing the various V-numbers (Vx, Vy, etc) and proceed with Phase I testing.

I do not have any gear leg or pant fairings installed yet and the a/c is not painted. My question: once I have established the various V-numbers, will they change when I install the fairings, pants an paint?

If they do change, how different will they be? I understand that top speed will change, and the approach speeds vs RPM may change, but I don't know about the others.

 

[dmaib]

I am not an engineer, (just ask gmcjetpilot) but I don't think you will see any difference in V-speeds with fairings and paint. I can tell you that mine did not change after paint and fairings. Top speed jumped 12 to 15 knots! I suppose upper gear leg fairings could have some small effect on the wing, but I cannot imagine it would be significant.

 

[pierre smith]

Hi Noel...

On our -6A I saw an added 200 FPM in climb and 16 MPH faster. The stall speed didn't change but the Vy did in higher numbers.

BTW...the airplane was a lot more reluctant to slow down all clean. No big deal, it just took a little longer and getting used to it.

Best,

 

[Kevin Horton]

I have about 8 hours on my new Superior engine, have remained within the airport environment so far, and now am ready to embark on establishing the various V-numbers (Vx, Vy, etc) and proceed with Phase I testing.

I do not have any gear leg or pant fairings installed yet and the a/c is not painted. My question: once I have established the various V-numbers, will they change when I install the fairings, pants an paint?

If they do change, how different will they be? I understand that top speed will change, and the approach speeds vs RPM may change, but I don't know about the others.

Vx and Vy will almost certainly increase a few knots when you install the gear leg fairings and wheel pants. The final Vx and Vy flight testing should wait until the aircraft is in the final aerodynamic configuration. But, it takes some practice to develop a good flight test technique, and there is no harm in doing some practicing now. Practicing now will improve your technique, and help you get better data when you do the final flight testing.

 

[noelf]

Thanks...

...for the info. It looks like I will end up with two sets of V-numbers: one set for aerodynamically clean, and another set for draggy (no fairings or wheel pants). Looking forward to the adventure...

 

[Kahuna]

Getting V numbers for your plane, is pretty much an acedemic exercise. These numbers are readily available and your not likely to be off more than a margin of error for reading accuracy.

Flight testing in todays RV world is not a test so much, as it is to build attitude, dicipline, and oneness with your plane. Become one cohesive unit is the key to your phase 1 time. You and the plane. I dont know your back ground, but in general terms, YOU need the test more than the plane does in all likely hood. You are more of the risk than the plane performance is. I teach new pilots that the test period is testing THEM more than the plane. Flying the entire RV envelope for most RV'ers is flying way beyond where they have been comfortable before. The flight hours will take time for the pilot to build to it. The plane was ready at the 3 hour mark.

My 2 cents.

 

[Rick_A]

No expert here

I'm certainly no expert on this topic but one of my main objectives during the first 20 hours of flight test was to make sure I did a good job of breaking in the engine.

My main objective during the first 20 was to run the engine hard without over heating it and building confidence in the reliability of the plane. I only did enough slow flight to make sure that the plane behaved well and to give me a feel for the plane.

I did most of the real flight test tasks during the 2nd 20 hours.