Hi All,

I run across this article: http://www.vansaircraft.com/pdf/hp_limts.pdf

Granted it is from a kit plane (experimental) manufacturer, I believe what was stated, if true, should apply to certified airplane as well. Although I don't always agree with Vans, I always have great respect with what Vans has to say. Given that I am not an aeronautical engineer, I am inclined to accept this article as being correct.

Here is my question for you TN guys: I recall my S35 having a Vne of 225 mph which is about 195 knt. I also recall my friend's former 1981 A36 having the same Vne. I also read many of you stating speed in TN Bonanza with 550 engine at altitude could be as high as 205 knt ture. If the article is correct that Vne should be true air speed rather than indicated air speed, doesn't that put your TN Bonanza true air speed above Vne when you are cruising at 205 knt?

Robin Hou
S35 N7947K

Good question, that VNE sure sounds low...

IIRC, Vne is a function of IAS, but flutter is a function of TAS. Maybe that's why some might think that Vne should be done in TAS.

Dunno.

I'm no aereonautical injuneer.

Flutter is based on TAS I think because of the SPEED of the air molecules not the pressure or (airspeed)

I like to go fast. While I've never been at Vne in an A36 I've been pretty dang close. The red line is on the IAS guage not the TAS guage which is not on my panel. If Beech thought is was important I suspect they would have put one there.

I am scared to death of VNE and fly mostly around the top of the green (Irish heritage) or low yellow (mellow yellow from the sixties). Maybe I have been reading too much John Eckalbar and his treatise on vertical acceleration loads.

I punch the autopilot disconnect at the slightest turbulence, not wanting to stress the control cables, et al. Given that I have one of the fortunate V-tails with a IO-550 and Tornado Alley turbo, am I being too conservative?

Kelly:

WFIW, if you're being to conservative, so am I.

I stay out of the Yellow arc, too. I read John Ekalbar's book more than a decade ago and have stayed impressed. Besides, my airframe is 39 years old.

(I wish my airframe were as tough as Bret Farve seems to be at 39. Whew! I know I wasn't and it's only gotten worse.)

Flutter is indeed related to TAS (actually "Equivalent Airspeed but there's not much difference below 250 KTAS) but AFaIK things are as bad as the article by Ken Krueger suggests. This is because Vd (IIRC Vne must be no higher than 80% of Vd) is established at something like 75% of the service ceiling of the aircraft. I assume that would be about 14,000 MSL so the equivalent of a Bonanza's IAS Vne would be around 250 KTAS and there's a 25% margin above that if everything is in good shape. So IMO as long as you keep the TAS below 250 Kt (e.g. below 170 KIAS @24000 DA).

Yes. But that's for you to choose. Actually, I do believe in staying out of the yellow arc unless you're certain you'll be in "smooth" air. It's the worry about stressing the control cables that's a bit too conservative. If they aren't spitting out strands they won't break no matter what you or the autopilot does.

Lance,

Agreed the cables are a non issue, if in good shape. And if in poor shape, they should be replace no matter what speed is flown.

There are changing limits to the KIAS on a lot of planes as on climbs above FL200. They decrease. For you TN guys are there any such limits? My Chieftain had limits. And almost all turboprops and jets have them. Not and injuneer, but believer flutter is part of the issue.

I'm also in the "don't fly in the yellow" camp. No need to.

im no injuneer either. but if you do the turbine conversion to an A46, it eliminates the yellow arc all together, Vne does NOT change though. all that means is that the A36 is much stronger than beech wants you to think. I believe the yellow arc is for full power descents in baby butt smooth air... btw, i hit 249 GS the other day on the way down. I didnt ask atc for a GS check..... dying to break the 250 barrior

I am perfectly willing to be educated here...but I was seriously considering one of the Tradewind turbine conversions and I was lead to believe that the yellow arc was indeed eliminated because VNE was at the START of the old yellow. And there was a very annoying, not turn-offable buzzer to enforce that.

I never got around to flying one, but I believe that the above is correct.

Jim

Well, I am an engineer, but no interest in being a test pilot! Good goal as long as it is the wind that helps with the breaking, and the dying is figurative!

I do think that for any piston to turbine conversion, Vne moves down to end of green arc.

Vne doesn't "change" it simply goes away as the upper airspeed limit in such a plane is called Vmo (V max operating). But that's just semantics and acronyms, the practical effect is that you cannot legally fly at an IAS above the top of the original green arc renamed from Vno to Vmo.

And while this may also have the effect of reducing the risk of flutter, it's my understanding the reason behind this requirement is that turbine powered airplanes generally have the ability to exceed Vmo (top of green arc) in level flight over a wide range of altitudes.

I too, am interested to hear if a TN conversion comes with a Vne reduction with altitude like the 58Ps have. Also do the factory turbocharged Bo/Barons have altitude adjusted Vne?

If so it would seem prudent to adhere to the same limitations in a TN Bo whether or not the TN STC imposes such a restriction.

Isn't that one of the causes the Malibu's were breaking apart in the early years? The FAA recommended more training to prevent over speeding.

I have to admit that I love medium power cruise descents at speeds midway into the yellow arc. I only do it if the air is completely smooth and I'm VFR. In the P35, Vno is 161 KIAS and Vne is 195 KIAS. My personal Vne is 175 KIAS. As soon as I feel even the slightest bump, I reduce power and bring the nose up enough to bring me back under Vno. The aircraft is designed to operate in that realm. Why not enjoy it?

Oh, and I am an engineer.

My concern is that the plane was designed to operate in that realm with all parts were new. Once it gets to be 50 years old, I assume that it's no longer at 100% of its original strength.

Also, depending on rate of descent, around the Great Lakes you can get layers of wind shear and hit some fairly good bumps without warning.

My concern is that the plane was designed to operate in that realm with all parts were new. Once it gets to be 50 years old, I assume that it's no longer at 100% of its original strength.

Also, depending on rate of descent, around the Great Lakes you can get layers of wind shear and hit some fairly good bumps without warning.