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RV 3B - VNE & Empennage

Paul Walter

Active Member
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 that’s 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
 
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.
 
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.
 
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
 
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.
 
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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As I said I’m 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. I’ve read guys have 240 hp in RV 4 and so on and don’t 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 that’s 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 it’s still out there doing it’s thing ?.
 
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/vertical-stabilizer-bracket-mod
 
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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.
 
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 Mothership‘s site the other day, but couldn’t find it... any idea where that bulletin is :confused:
Thanx!
 
Very little to add to the excellent points above, other than you might consider installing a C/S prop on it, if overspending during aerobatics is what you are afraid of. A prop flattening out can be quite an effective aero brake when compared to a fixed pitch prop.

Or indeed... be careful and just enjoy the aircraft for what it is... :)
 
Ask Smokey

I tried to locate the Vne article on the new Vans site but had no luck. Google had no trouble finding it. Smokey (on the forum here) may be able to send it to you as he wrote part of it.
 
Thanks Scott and Skysailor.

I'm aware of said 5 pages containing various articles about not installing turbos, not installing engines that are too powerful in the RV-9, Smokey's report, etc, thanks. This document is found in the SUPPORT, TECH Q&A.

The use of TAS iso IAS as Vne is serious matter, and I thought a safety bulletin specifically addressing this had been published, and that I might have missed it :eek:

Instead we have an actual table, see https://www.vansaircraft.com/faq/airspeed-indicator-markings-by-model/, where the Red Line figures don't even mention being TAS :confused:
Even worse, section 15 of most construction manuals presents a table labeled Airspeed Indicator Markings for all models, the legend for the highest speeds listed being: Red Line: VNE IAS (Maximum permissible speed under any condition) :confused:

IMHO, quite a few builders, plus an increasing number of RV buyers are not aware of the TAS as Vne limitation...
 
Kicking a dead horse

The topic of VNE, IAS, TAS has been discussed at length through the decades on VAF and at Vans. I along with BillL and others have tried to get some movement at Vans concerning this but to date no response except for what has already been shared publicly. I would imagine that there are other factors at play here so I won’t sit on judgement except to say that folks who operate a Vans aircraft design without knowledge of TAS limitations should not be flying. However, that’s just my opinion and my motivation for being blunt is maybe to shock someone into doing their due diligence BEFORE strapping in and before hauling a passenger. In this case, ignorance is not a defense, just another causation event and higher insurance and a smaller pilot pool.
 
Thanks Scott and Skysailor.

I'm aware of said 5 pages containing various articles about not installing turbos, not installing engines that are too powerful in the RV-9, Smokey's report, etc, thanks. This document is found in the SUPPORT, TECH Q&A.

The use of TAS iso IAS as Vne is serious matter, and I thought a safety bulletin specifically addressing this had been published, and that I might have missed it :eek:

Instead we have an actual table, see https://www.vansaircraft.com/faq/airspeed-indicator-markings-by-model/, where the Red Line figures don't even mention being TAS :confused:
Even worse, section 15 of most construction manuals presents a table labeled Airspeed Indicator Markings for all models, the legend for the highest speeds listed being: Red Line: VNE IAS (Maximum permissible speed under any condition) :confused:

IMHO, quite a few builders, plus an increasing number of RV buyers are not aware of the TAS as Vne limitation...

We are fully aware of the disconnect between these different pieces of information and there is effort underway to correct it.
I know that has been mentioned before, but with the man power and other challenges that have occurred in the past year, it just hasn't happened yet.
 
This discussion was going around our hangar a while back. Just to be clear VNE being defined as IAS or TAS is based on many things. Many aircraft use IAS for VNE. It comes down to what are the limiting factors in a specific airframe design. If for example the flutter margin is above the airspeed where non flutter structural failure can occur than IAS will probably be used to define VNE. If flutter occurs before possible structural failure than TAS would probably be used. Vans seems to have provided clear guidance that TAS is applicable to the RV airframes but that does not extend to other types. Each is unique.
 
This discussion was going around our hangar a while back. Just to be clear VNE being defined as IAS or TAS is based on many things. Many aircraft use IAS for VNE.
e.

Actually, ALL type certificated aircraft use IAS for Vne, because the FARs require it. (A placard stating different Vne, in IAS, for different altitudes, is allowed.) Although EAB aircraft are exempt from this (part 23) rule, it is nonetheless somewhat confusing to owners new to EAB that Vans chose to go a different way.
 
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