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Michael Henning
07-24-2012, 05:20 PM
What is the vne on a Rocket?

tobinbasford
07-24-2012, 05:42 PM
This says 310mph for Rocket 3: http://www.harmonrocket3.com/HR3_Specs.html

pierre smith
07-25-2012, 04:42 AM
Mike, I'd say that nobody really knows. Consider that the Harmon Rocket uses RV-4 wings and tail, though with thicker skins, and the -4's VNE is 210 MPH.

Independent testing to the aforementioned 310 MPH is where the builder put it, not Van's...so who decides what it is?

Best,

f1rocket
07-25-2012, 04:45 AM
IIRC, the F1 Rocket Vne is 260 kts.

F1Boss
07-25-2012, 06:36 AM
IIRC, the F1 Rocket Vne is 260 kts.

The Sport wing F1 uses 240KT as its Vne, as does the HR2. The F1 Evo uses 250KT, as it has the stronger empennage assy.

The Vne numbers are quoted as a TAS number, so be careful when at altitude.

Be careful comparing the Rocket with the RV4 - they are definitely NOT the same. We would not want a -4 driver to expect his ship to withstand the 240kt Vne of the Rocket series.

In the end, each ship is tested during Phase 1 to some number, and THAT is the Vne for that specific airframe as listed in the aircraft logbook. Hopefully, this testing is done with a calibrated pitot/static system.

Carry on!
Mark

Michael Henning
08-08-2012, 12:19 PM
Thanks guys. I will be using 210 as my vne, but was curious to what I should actually test to.

cptbuzz
08-08-2012, 03:26 PM
Vne of the HR2 is 275

Bob Kuykendall
08-08-2012, 04:23 PM
Thanks guys. I will be using 210 as my vne, but was curious to what I should actually test to.

I think that the customary definition for Vne is something like "87% of the greatest speed shown to be safe during flight test." Basically, you either choose a speed and then test the airplane to demonstrate that it is safe at a speed 15% greater, or you go as fast as you dare and then define the Vne as 87% (1/1.15) of that. Both methods involve no small risk.

The kinetic energy that drives flutter and other undesirable behaviors scales with the square of the speed. Above 200 knots, when bad things happen they do so with violent authority. The development history of the 400+ knot airplanes of WWII and later was written with blood, buckets of it. There be dragons there.

As a side note, I am a proponent of the theory, advanced with no small rigor by a couple of aero engineers I know, that where Vne relates to flutter it can safely be aligned with a speed that splits the difference between IAS and TAS. But that is a topic probably better pursued in the "Never-Ending Debate" area.

Thanks, Bob K.