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Fastest RV ever

Dave Anders.....

....a California dentist (Dave Anders), holds the world record, certified by the CAFE Foundation, of 265 MPH, straight and level, in his RV-4.

I have seen 212 MPH TAS WOT, in my -10.

Best,
 
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Chris
I feel that you have pushed the envelope quite a bit here. I believe the published Vne is in the 200 knot range? Yes there are RVs that have gone faster but you are treading on dangerous territory. No one really knows what one bump of turbulence would do do your aircraft at these speeds. You are in control of the speed during descent and there is no reason to let it get that high. A parachute might be a good idea if you are going to test speeds at that extreme. When Van publishes a Vne of 200 (203?) that means that it is the fastest that they believe the aircraft should safely go. Vne stands for NEVER EXCEED SPEED; sounds pretty clear to me.
Forgive me if I have the actual Vne number wrong for that aircraft, perhaps someone with a RV8 can step forward with the actual number.
 
Tom,

Keep in mind Chris posted KTAS (knots TRUE airspeed) not KIAS (knots indicated airspeed). Big difference.

One could easily have 223 true and still not be above 200 indicated.

Of course it is also true that on a given day/ altitude, it would require being above 200 indicated to have 223 true.

I am assuming he had his I/T spelling correct.

Mark
 
What do you want Indicated or TAS?

I don't think there is a "Indicated/TAS", its one or the other.
I saw VNE (210mph) in my 6 at 9,000' WOT desending at only about 250fpm last weekend. It is very easy to reach VNE at altitude as has been discussed before. Be careful.
 
There has been lots of discussion in the past whether to use TAS or IAS for determining Vne. Based on an article by Ken Krueger Vans use TAS for Vne determination. It is at altitudes above 8000 feet where it is very easy to bust Vne if you put your nose down and just look at IAS. As I understand the debate the higher we go we should use a theoretical "equivalent airspeed". This number will be less then the TAS number but greater then IAS. In practice it is better to use TAS as it is easily calculated and many of the new EFFIS units will display TAS. I have no idea how one calculates "equivalent airspeed" or the science behind it; using TAS will err on the safe side. Before relying on any airspeed information, the system needs to be calibrated, especially if one is to push the Vne envelope.
 
well, I guess i was up to about .37M :) It was a calculated risk on my part: smooth air, good sky conditions, rural area. 250 mph in the RV8 is certainly doable.

I dont know that Vans actually tests for VNE for the airframe since they have apparently not ripped the wings off in testing flutter. Must not have found that limit yet...

I dont know how much (if any) faster I would go over 223 ktas since I'm not getting paid to expand this envelope, but its neat to know my plane will haul arschnit if i want it to.
 
I'm curious about the IAS vs. TAS discussion as related to RV airplanes. In every transport category airplane I've flown, limiting structural airspeeds (Vne, Vfe, Va, etc.) is based on KIAS (actually CAS-calibrated airspeed, but that's really close to IAS). The loads imposed on the airframe and control surfaces is lower for a given TAS is less dense air at high altitudes. There isn't a huge variation in TAS vs IAS at the altitudes we fly in our RV's, but there is some. I know I can be indicating 200 KIAS in my RV-8 and have a KTAS of well above that - by maybe 15-20 knots. I don't fly at that airspeed, but I don't think I am exceeding my Vne in this situation. If I am wrong about this, I'd like to know, and would be interested in knowing why.
 
flutter vs structural loading

as i understand it, flutter limits are driven primarily from the potential for divergent harmonic forces on control surfaces from actual airflow... the molecules of air passing the control surface producing a vibration that will tend to get bigger rapidly... for flutter TAS is key. for air loads on the structure IAS captures the mass force resistance of the air similarly regardless of pressure, temperature, or altitude...
 
How fast does the RV6 Rocket go?

How I determined my typical cruise speeds for the I.O. 540 RV6;
To get the most accurate numbers I do a 3 way run at a specific altitude. I go 120* 240* and 360* with altitude hold on. I wait for the speed to stabalize, then record the numbers. I do this three times. That's a total of 1080 degrees. I add up all the speed numbers and divide by 9.

Here are the typical numbers I get from the test, and the numbers I'm most likely to cruise at.
2100 rpm 19" MP OAT 13.9c at 8500' 194 mph @ 8.8 gph
2200 rpm 22" MP OAT 13.8c at 8500' 215 mph @ 10.9 gph

It will cruise at 229 mph, but gets noisy and burns a lot of fuel, and way too close to my 230 mph VNE. Down low and wide open, I really don't know how fast, but too fast for me. Steve Barnes "The Builders Coach"
 
Depends how high you are, and the environmentals...

Also "knots" is defined as "nautical miles per hour", so knots per hour is really nautical milies per hour per hour, or a definition of acceleration, not speed.

Mach 1.0 @ Sea Level = 1,225km/hr, 761mph , 661kts
Mach 0.3 @ Sea Level = 367km/hr, 228mph, 198kts
 
Fast fliers typically equate Mach Number (although a bit inaccurately) to 1 Nautical Mile per Minute per each 0.1 Mach (rule of fat thumb).

So, 0.4 Mach in fighter-pilot terms = 4 nm/min = 240 nm/hr.

Worked fine flying low-levels using maps in Europe.

Now, in our little birds claiming .4 Mach is probably exaggerating. Based on the prior post about the speed of sound, 0.4 would more likely be something like 265ktas / 302 statute mph tas.

We also used a rule of thumb of "1 degree = 100' per nautical mile," so en-route descents were fairly simple to calculate. If your airspeed is 0.5 mach and you descend at 5 degrees, your rate of descent will be 2500' / minute (5 degrees * 100' = 500' / nm; .5 mach = 5 nm / min; 500' / nm * 5 nm / min = 2500'/min). Lots of uses for those silly rules of thumb to help you plan ahead.
 
RV8 VNE

As published in my 8 construction manual, in a table titled "AIR SPEED INDICATOR MARKINGS", VNE for the RV8 is 230 statute miles per hour.

This speed should be marked with a red line on the airspeed indicator.

Since we think RV's are VNE limited due to flutter issues, TAS needs to be monitored, as described in the aforementioned article. Compliance with the IAS/EAS/TAS guidance is up to you.

edit: more to the topic, I took my RV4 (with .016 tail feathers) to 230 mph indicated, which was VNE plus 10%. What I wasn't thinking about at the time, I did this at around 12000 MSL, just in case I had to jettison the airplane. In the summer. So, the TAS was in the vicinity of 280 mph :eek::eek::eek:

Not gonna do that again.
 
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RV8 Vne

So am I getting this right? Vans recommends, in the construction manual, Vne is 230mph indicated. Then he posts this http://www.vansaircraft.com/pdf/hp_limts.pdf implying it should be 230mph true.

Also, consider, in the article about HP Limits, there is a sub-section about a RV-4 breaking the true airspeed Vne and encountering flutter, but now Bill Wightman says his RV-4 did indicated Vne+10% at 12,000' and did not encounter flutter.

Is this differences in build quality? Eg. better balanced control surfaces.



On a side note, shouldn't the indicated numbers posted by Vans actually be read as calibrated numbers, since every installation will have different instrument errors?
 
I actually called VANS once and they confirmed that they were sticking by TAS for VNE. I suspect that this is simply being prudently cautious. It typically isn't a problem for most models in straight and level cruise if you stick to the recommended engines, but there are always those seeking to mount a bigger / turboed engine.

As always, I recommend that people stick to the posted design limits and, if you just have to go faster, select an airframe designed for those speeds.

Now, here is an interesting thought: Since flutter is based only on control surfaces, what would happen if someone were to build a hybrid RV-X using tail and wings from "some other airplane?"

:D
 
Flutter depends on true airspeeds and is usually potentially more of a problem at higher altitudes, where there's less atmospheric dampening.

In FAR Part 23 (which a homebuilt doesn't need to follow) Vne is set at 90% of Vd, which is the certified max speed. So Bill's test of his RV-4 was rational.
 
Now, here is an interesting thought: Since flutter is based only on control surfaces, what would happen if someone were to build a hybrid RV-X using tail and wings from "some other airplane?"
I think you'll find that aerodymanic flutter can occur to any part of the aeroplane, not just the control surfaces. To think it limits itself to just the movable surfaces is a dangerous train of thought.

That it usually occurs on this part of the airframe is simply because they are the most movable parts. Fly fast enough and you could well find your entire wing doing the higgidy-diggidy. For those who remember Ken Rand (of KR fame), he was doing a movie shoot with KR-1, fitted with a large dummy antenna to simulate a "drone". It got to a point that flutter set in, and he thought he'd shed a prop blade. He hit a tree on the approach and rolled the KR up into a ball. Survived though...

As usual, NASA has a beaut Youchoob video showing a spam-can undergoing flutter testing. Scary stuff.
 
Chris
Yes there are RVs that have gone faster but you are treading on dangerous territory. No one really knows what one bump of turbulence would do do your aircraft at these speeds.
A turbulence bump or a small control stick input can excite the structure to flutter. Be carefull thinking that just beacause someone flew above a Van's listed Vne does not mean it is safe for all to fly at those speeds.
I dont know that Vans actually tests for VNE for the airframe since they have apparently not ripped the wings off in testing flutter. Must not have found that limit yet...
You can calculate flutter speed if you know the structual stiffness and all bending modes. Not an easy calculation and not very accurate. Not sure how Van's set Vne but do not believe he did a full flutter test. At the big companies they can only fly to a certain percentage of calculate flutter speed if no flutter test was done.
I think you'll find that aerodymanic flutter can occur to any part of the aeroplane, not just the control surfaces. To think it limits itself to just the movable surfaces is a dangerous train of thought.

That it usually occurs on this part of the airframe is simply because they are the most movable parts. Fly fast enough and you could well find your entire wing doing the higgidy-diggidy.

As usual, NASA has a beaut Youchoob video showing a spam-can undergoing flutter testing. Scary stuff.
Excellent video showing that the fixed structure can flutter just as easily and a movable control surface.
 
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Guys - my previous post was absolutely NOT intended to say the RV4 is safe at speeds above the published VNE. Knowing what I know now, I would not repeat the test again. I basically tested my airplane to design dive speed, which is 10% above published VNE for certified aircraft. My rationale was to test my RV's flight envelope to the limits called out in FAR23.

I personally have found it hard to find good clarity on the VNE issue. I too called Vans and got a different answer than what was reported earlier in this thread. Depends on who you talk to, it seems to me. What we're dealing with now, in my view, is confusion stemming from having the published VNE as an indicated speed, while saying in their newsletter it should be TAS. Construction manuals sent out subsequent to the newsletter article did not contain corrections to put the two in agreement.

So, my *suggestion* is to search the forum and settle the matter for yourself. There's plenty of information: a wide range of opinion, thoughts on the "HP Limit" article, and enough technical input here on VAF to choke a horse.
 
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