|
|
Hi Dave (and welcome John),
I agree that this (TAS) is really strange and not intuitive. But consider the source - Van himself!!! When I read this in RVator I had doubts but I gotta go with John on this unless we hear from another impeccable source to the contray. TAS it is!!!! Call Van if you need more info; I doubt any of us (do we have any aeronautical engineers on the list? I know we have every other flavor of engineer here!) have the knowledge to debate this with Van.
--
Ken Powell Bryant, Arkansas 501-847-4721
------------------------------------
Well yes we have an engineer with an aero degree, me; but do not proclaim to be an expert on flutter. I spoke to Ken Krueger at length on this subject. First ,Van does not have any flutter expertise on his staff and hires his work out to a flutter engineer here in Vero Beach.
I would have bet it is a function of IAS because the driving forces are a function of dynamic pressure, but the exciting force may in fact be a function of TAS. The thing that excites flutter is the shedding of Von Karmin vortices and you can see how there frequency would be more a function of TAS and their strength is related to the IAS. On the other hand, it does not take a very large hammer to destroy a surface if you hit it as its natural frequency. Now you are basically up to speed with Ken and myself. When Ken looks at the "experts" analysis , the exciting frequency is with TAS. Now saying this, you have to believe that Van put a large "kitty" on the number to take care of the unbalance surfaces and other variations among the homebuilt kits.
Look at the speeds that Tracy Saylor turns in his RV6 and Dave Anders in his RV4 to know that there is some degree of margin. I would test the water gingerly with stick bumping as I increased speed at a safe altitude and be alert with an outlet plan such as power off and climb to kill the flutter. I don't know, but I think it is streching it some to believe that a naturally aspirated RV is going to exceed 200 with a reasonable fuel burn, but some of the high time rotary RV pilots should comment on that subject.
Bernie, 20 hours of 40 flyoff, have flown 7 days straight , tough living in S Fla
|
|