Vne, TAS and flutter.

[kmyfm20s]

This was news to me that Vne was a moving target established based on TAS and NOT IAS. It a great article for some of us that like to do our descent in the yellow arc, have increased HP, or are high flyers. At times the margin between the bottom of the yellow arc and top are smaller than expected. Any input from the propeller heads on board would be appreciated

www.vansaircraft.com/pdf/hp_limts.pdf

Karson

[RJBrown]

Vans is trying to limit legal exposure from the "Rocket" versions of their kits by expressly distancing themselves from higher powered versions. Harmon Rocket & Team Rocket sell modified versions of Vans kits that house much larger engines. 540 CI and 300+ HP vs.. 360 CI and 180HP as recommended. Though impressive planes they go against all that Vans stands for.

 Rocket Engineering had completed the flight tests to increase the certified ceiling of the 305Rocket conversions to 30,000' but failed to jump through all the FAA's hoops because of high costs and low return of value. They believed the plane met those requirements but did not spend the money to get the FAA to certify it. Our planes ARE that well built.

 Until someone chose to fly into a thunderstorm and come screaming out the bottom in a Rocket there had never been an airframe failure/flutter incident on any metal spar Mooney in history. Our planes, even with 300+ HP engines, have proven to be the strongest, safest plane in their category. Unlike the fairly common tail failures of Beech and Piper products.

 Because of the safety record Mooney is the only product I would consider. Bonanza Malibu and Saratoga have all shown a propensity to shed tails.

[Skywarrior]

The only thing an airframe 'feels' is IAS...

[Super Dave]

The only thing an airframe 'feels' is IAS...

Not true; flutter is a function of TAS

[Alan Fox]

Actually Beech fixed the tails with a Mod , and they don't come off anymore , they never did unless the plane was flown outside of the published envelope......Fly any plane outside of its envelope and it will bite you ANY !!!!!

[DS1980]

Good article. Thanks.

[Jerry 5TJ]

 RJBrown said "…Because of the safety record Mooney is the only product I would consider. Bonanza Malibu and Saratoga have all shown a propensity to shed tails…."

 

 I tease Bonanza owners by pointing out that if they lose control in the clouds, their airplane will come apart, whereas if we lose control in IMC our Mooney aircraft will impact with the airframe intact...  

[PTK]

All speeds on the ASI are based on IAS with the exception of Vne (Red line.)

This is because it takes into account service ceiling and protects against exceeding it in a descent from altitude. (If Vne was based on IAS it would have to be lower as we approach the service ceiling.)

The difference between TAS from IAS is altitude dependent.

We can easily exceed Vne if in a descent from altitude.

[Alan Fox]

Actually its a little more complicated than that , I read a ten or 12 page article explaining speeds and flutter , and you seriously would need an engineering and math degree to begin to comprehend it .... I just don't approach the red line in any plane........

[aviatoreb]

Its not so complicted from a pilots 

 

Actually its a little more complicated than that , I read a ten or 12 page article explaining speeds and flutter , and you seriously would need an engineering and math degree to begin to comprehend it .... I just don't approach the red line in any plane........

 

Its complicated from an engineer's perspective, but not so complicated from a pilot's perspective.

 

That Van's article is written for the homebuilder/homemade engineers.  It reminds that flutter depends on TAS not on IAS.  So that must be considered when flying high.  Flutter is especially dangerous for gliders that fly in the mid to upper 20's, since flutter is also especially likely to strike long thin wings like on a glider.

 

If you are not flying experimental, but you are flying certified, its easy.  Fly within the certified envelope.  The certification process is (supposed to be anyway) designed to present safe margins including no flutter.  So if my airplane is certified to 196IAS at 24,000, then that corresponds to a TAS which will be free from flutter (and is it a safety margin further than 1.3 times that?  I always forget that constant).  That's for the flight test engineers to worry about.  For the operating pilot - stay below certified Vne and within certified ceiling and you will be fine.  There is no need to know how much faster or higher you can go since we will not go there.

 

Now if you are a homebuilder making your own design, you are both flight test engineer and test pilot.

[rob47v]

Actually Beech fixed the tails with a Mod , and they don't come off anymore , they never did unless the plane was flown outside of the published envelope......Fly any plane outside of its envelope and it will bite you ANY !!!!!

Beech a wonderful airplane for comfort and economy as far as speed that is. But they are expensive to maintain. And yes Beech has resolved their tail issue but still from time to time get plagued with speed restrictions. I use to own a bonanza loved it but seriously dollar per dollar the mooney is the best buy. Fairly clean cheap to an extent to maintain, cheaper on annuals believe me, lower cost to fly, at lest the 4 cylinders are. I loved the Viking I also had but the 6 cylinders love to drink. Coupled to the special treatment they require. Well forget it. they are a bit on the expensive side of things not by much except the hanger requirement thats a biggy.