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  #1  
Old 03-27-2021, 11:38 PM
Paul Walter Paul Walter is offline
 
Join Date: Jun 2010
Location: Horsham, Victoria, Australia
Posts: 90
Default RV 3B - VNE & Empennage

Hello everyone, I am looking at an RV 3 at the moment- very neat well built example. It has io320 and Catto cruise prop. This thing is a rocket ship indicating 165knts at 1000 feet thatís 25 knots faster that my RV 6 was and 20 faster than my 7A was. I know this has probably been well and truly covered before but I am concerned with ripping through VNE with out even trying. Are vans quoted VNE speeds indicated air speed ?. A guy at an air show told me he flew his on RV 7 numbers and never had an issue but I live on the safe side. So I was wondering would it be wise to beef up the empennage?. Is it true the Harmon rocket used a standard RV 4 tail ?. Would heavier skins be enough or would the hole structure need to be beefed up and if so has anyone done it and what modifications were made.

Thank you
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  #2  
Old 03-28-2021, 12:32 AM
oaklandaviator oaklandaviator is offline
 
Join Date: Dec 2014
Location: Somerville, Tn and Little Rock, Ar
Posts: 143
Default Vne

185 knots TAS on the 3, I believe. Not hard to manage, especially with any EFIS that varies the redline for true airspeed. Just pull back the go-go lever a bit and don't overspeed. Start a slow descent, get the engine temps coming down, then shoot for 700 - 800 fpm. Use 500 as a minimum and 1000 as a maximum. That'll keep your engine pulling a bit and prevent shock cooling. Throttle as required for speed control.

Have fun. They're awesome airplanes.
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  #3  
Old 03-28-2021, 05:02 AM
Skysailor Skysailor is offline
 
Join Date: May 2011
Location: Atlanta, GA
Posts: 293
Default True air speed

Vne is measured in true airspeed as mentioned above. The factory put out a bulletin confirming and clarifying this in the not too distant past.
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  #4  
Old 03-28-2021, 09:08 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 5,059
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210 mph which is almost 183 kts, and it's TAS.

On a few RV-3s, the builder installed mass balances. As far as I know, there have been no reported cases of flutter or accidents due to flutter on RV-3s. Because of that, I did not install them on my RV-3B.

As for stiffening up the components, it might well take more than thicker skin, although that would be one of the things to consider. Flutter isn't something that a casual builder can be sure of addressing properly; it takes decent analysis and testing with instrumentation.

If the plane is built well and flies well, buy it and enjoy it within its published limitations.

Dave
Now setting up the cockpit area on my RV-3B
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  #5  
Old 03-28-2021, 10:59 AM
Richard RG Richard RG is offline
 
Join Date: Jan 2021
Location: British Columbia, Canada
Posts: 23
Default RV3 VNE

The builder of my RV3b has indicated that 207 mph, 180 knots is the VNE. Though I haven't done any aerobatics yet, have discovered that it is very easy to hit VNE during some inspired maneuvering, much moreso than other less aerodynamically clean aircraft.
Having installed a Uavionics AV-30 in the panel, as well as connecting an OAT probe to the AV-30, now always have true airspeed information available.
Setting various limits in the AV-30, including VNE has proven very useful, having discovered that the AV-30 really commands your attention when approaching airspeed limits.
During aforementioned inspired maneuvering discovered that the RV3 can accelerate VERY quickly through VNE and although I was more intent looking out of the aircraft, was given a clear warning by the AV-30 to smarten up, as I was very quickly approaching VNE.
I think rather than structural upgrades or changes to aircraft, would be a better plan to never exceed the limits set by the designer and consider some of the aids available to enhance situational awareness.
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  #6  
Old 03-28-2021, 11:01 AM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,829
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Just to reinforce the good points made so far, if you decided to “beef things up”, you’d have absolutely no idea if you’d done any good (or harm?) anyway - flutter is just too complicated for the “that Looks about right” builder to address. I have also seen RV-4 tails put on souped-up RV-3’s, and no one can still prove that they did any particular good.

I have the challenge of having three RV’s, all with different Vne’s, and our RV-3 (IO-320, lightweight C/S prop) will exceed redline at sea level at full throttle and rpm by 8 knots in level flight - so I have to be really careful to think about which airplane I am flying, and pull the throttle back, especially at altitude, where we live. Our RV-8 has the highest Vne of the RV’s in our stable, and I even have to be careful with it not to get over redline. Just teach yourself to think of al that extra power as being there for climb, not speed, and use it wisely.

I once asked Van what kind of Vne and flutter testing he had done on the RV-3. Remember, this was a LONG time ago, and he was using smaller engines than we do now. His answer was something to the effect that he “probably” dove it to 10% over redline and called it good. So don’t expect a lot more information out of the mothership on the -3. Just live by the limitation.

On the other hand, even thought they are quite slippery, the RV’s are actually easy to slow down compared to the little Subsonex - a couple of degrees nose down from level flight and the airspeed is up by 30 knots in a heartbeat! And no C/S prop or speed brakes to slow it down....

Paul
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Last edited by Ironflight : 03-28-2021 at 09:03 PM.
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  #7  
Old 03-28-2021, 06:27 PM
Paul Walter Paul Walter is offline
 
Join Date: Jun 2010
Location: Horsham, Victoria, Australia
Posts: 90
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As I said Iím conservative at best I just find conflicting info. I read once the late Ken Fowler used to dive his rocket at 280knt ( at night) and the plane had a standard RV 4 tail and he never had a problem. Iíve read guys have 240 hp in RV 4 and so on and donít seem to hear of planes just breaking up. I will just buy the plane and fly it carefully and well within its limits. Guys like Paul Dye, Rob Ray ect would have forgotten more about building and flying planes than I will ever know and I fully acknowledge this thatís why their input is so vital. Out of interest when John Harmon built the first RV 3 rocket was the tail standard RV 3 ?, what did he list the VNE for that plane the performance must have been incredible and my guess is itís still out there doing itís thing ?.
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  #8  
Old 03-29-2021, 09:23 AM
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Bob Martin Bob Martin is offline
 
Join Date: Jan 2005
Location: Charlottesville, Virginia
Posts: 1,277
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All good info above.
During the prebuy...look close at everything but especially the tail section and attach points. Look for edge distance on bolts and their locations. Inspect the front vertical Stab spar attachment for cracks, etc.
Make sure to use a mirror on a stick and look under the deck at the bottoms of the bolts and the longerons for extra holes that should not be there.

And yes, the rocket guys and go fast guys do make their parts stronger. I have read posts on here about what they do or did to increase the strength.
That said, my opinion is that Vans aircraft built according to plans and flown according to recomendations from Vans are good and safe.

The link below is not for the -3 but just for general information.

https://antisplataero.com/products/v...er-bracket-mod
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Last edited by Bob Martin : 03-29-2021 at 09:37 AM.
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  #9  
Old 04-19-2021, 02:47 PM
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dacronwall dacronwall is offline
 
Join Date: Oct 2013
Location: Palo Alto,CA
Posts: 110
Default RV-3 speed

Just my .02, but these planes are quite stable (allowing as has been said that the builder has observed all the proper details). RV-3's fly best when light. "Beefing" things up apart from thicker skins would not be something to do casually. My tail had .020" skins on it, and when it was racing had them replaced 2x if I remember right. I didn't build mine, but I have had it mostly apart and have done all the spar mods.
Mine was built in Bakersfield (1984) along side John Harmon and a couple other guys who pushed the limits of the -3. Mine was built with a parallel valve O-360 and a CS prop. It raced (and held speed records) in the '90's. She now has a hot IO-320 and a custom Catto prop and I can just about get to 200 kts in level flight on the right day. I have no problem getting 220-225 mph out of it which is well over published max. I have had it in a dive at 240 mph indicated.
While I don't encourage exceeding maximums, I have done it and it gives me confidence in my airplane. I have never experienced any disturbing oscillation or flutter, and all of this was extensively tested in Phase 1 as is noted in the log book. I know the builder of my airplane. That helps. He also built an RV-4 and a Harmon Rocket that races at Reno. It has clipped wings and a supercharged IO540 with dual EFI and water injection....quite the airplane. And I believe it does close to 300 mph. (282 mph qualifying lap at Reno 2016).
Bottom line, we are all test pilots to some degree. Find your own maximums and live by them. Fly safe.
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  #10  
Old 04-20-2021, 01:06 AM
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Dan 57 Dan 57 is offline
 
Join Date: Sep 2018
Location: LSZF
Posts: 795
Default

Quote:
Vne is measured in true airspeed as mentioned above. The factory put out a bulletin confirming and clarifying this in the not too distant past.
Was looking for this on MothershipĎs site the other day, but couldnít find it... any idea where that bulletin is
Thanx!
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