pre-buy Vne check

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A2022
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pre-buy Vne check

Post by A2022 »

some RV buyers do a good visual inspection but what about checking the most important flight characteristic, the demonstrated Vne? it seems that a reasonable buyer could ask for a camera to be installed in the cockpit and the seller demonstrate the Vne capability in the current condition as a qualification for purchase. if the seller will not do this, then walk away because the aircraft cannot be flown to limits as shown on its airspeed indicator. DO NOT accompany the owner for this demonstration because it could be the first time. start the camera at the beginning of the flight when the airspeed reads zero to ensure no airspeed bias has been added.
Steve Melton
RV9A, Superior O-320 (roller cams), WW 200RV prop, Dual impulse slick mags, CHT 330F, EGT 1300F, Oil pressure = 65 psi, B and C Alt, 1000+ hours
Freedom and Democracy are all that really matter.
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A2022
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Re: pre-buy Vne check

Post by A2022 »

an RV owner should always be able to state the max dive speed test of his aircraft and then be able to demonstrate that.

my Vne = 182 KTAS
my Vd = 192 KTAS (flight tested)

Vd is 5% over my Vne

Vd test flight for N531EM in final painted configuration, 192 KTAS (with music)
https://youtu.be/2LhFZwankY0
Steve Melton
RV9A, Superior O-320 (roller cams), WW 200RV prop, Dual impulse slick mags, CHT 330F, EGT 1300F, Oil pressure = 65 psi, B and C Alt, 1000+ hours
Freedom and Democracy are all that really matter.
https://www.rvplasticparts.com/

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A2022
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Re: pre-buy Vne check

Post by A2022 »

I asked a friend who had purchased an RV-9A, what is the flight-tested dive speed (Vd) of his aircraft? he didn't know. shouldn't that be listed somewhere with the qualification documents to ensure it is safe to fly to Vne? ideally, you should request that check as part of the pre-buy inspection so that it is in the purchased configuration. if the owner will not do the test, then hire a test pilot. in order to make sure it is safe at Vne, you should test slightly beyond Vne. a Vd that is 5% over Vne is probably a reasonable number in smooth air.
Steve Melton
RV9A, Superior O-320 (roller cams), WW 200RV prop, Dual impulse slick mags, CHT 330F, EGT 1300F, Oil pressure = 65 psi, B and C Alt, 1000+ hours
Freedom and Democracy are all that really matter.
https://www.rvplasticparts.com/

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bruceh
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Re: pre-buy Vne check

Post by bruceh »

I've never had my RV-9A near Vne. Don't plan on doing that test. What is the point? I don't fly the airplane at those high speeds or in that configuration. I trust Van's numbers and certainly wouldn't exceed them by any percentage.
Bruce Hill
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A2022
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Re: pre-buy Vne check

Post by A2022 »

my aircraft airspeed indicator has 182 kts (Van's RV9 published Vne 210 mph) as the Vne limit. this means the aircraft is capable and tested to those numbers. it doesn't take very long to reach Vne. if you sell the aircraft with the Van's published airspeed indicator markings and it has never been tested, you need to state that, otherwise how will the new owner know. in actual conditions you could have some turbulence, so I tested 5% over Vne in smooth air. my Vd = 192 KTAS. I recommend inspecting your canopy (or doors) latching mechanism before this test.
Steve Melton
RV9A, Superior O-320 (roller cams), WW 200RV prop, Dual impulse slick mags, CHT 330F, EGT 1300F, Oil pressure = 65 psi, B and C Alt, 1000+ hours
Freedom and Democracy are all that really matter.
https://www.rvplasticparts.com/

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A2022
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Re: pre-buy Vne check

Post by A2022 »

a couple of email questions for the rudder config for my Vd test :) (192 KTAS). so, here it is. I passed the test. (ymmw - your milage may vary)

during the testing my feet were firmly on the rudder pedals, not that it would have mattered much if the rudder had decided to flutter.

I believe the biggest consideration for rudder flutter is rudder weight, especially at the trailing edge. to increase rudder flutter margin, keep the rudder as lightweight as possible. you may even consider not painting it at all.

rudder strobe weight = 18 grams.

I don't believe the Anti-splat fwd spar plate does anything for rudder flutter. my reasoning for adding the plate is because I didn't like the bolt slots used the attach the rudder fwd spar to the horizonal spar and for bird strike. who knows if this is reasonable thinking, but it's added.

Tinlicker ft. Thomas Oliver - Need you (Anjunadeep Open Air, Prague) ("I need you to hold on" is an appropriate song for this test, streaking thru the sky at 220 mph)
https://youtu.be/eMg97_dx2OY

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Steve Melton
RV9A, Superior O-320 (roller cams), WW 200RV prop, Dual impulse slick mags, CHT 330F, EGT 1300F, Oil pressure = 65 psi, B and C Alt, 1000+ hours
Freedom and Democracy are all that really matter.
https://www.rvplasticparts.com/

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