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Hi Bernie,
I thought that you were a Mechanical Engineer; the talents on the list never ceases to amaze me. Thanks for the additional info; this is the first time that this computer programmer has heard of Von Karmin vortices. If you ask me about these in a week or so I will probably say "huh???". But an interesting look into flutter.
Ken Powell
Bryant, Arkansas
501-847-4721
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>
>
>
> 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
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
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