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  • May 20, 2022, 03:46:14 AM

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Author Topic: Sheeted LE  (Read 485 times)

Offline Ken Culbertson

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Sheeted LE
« on: May 02, 2022, 10:56:52 AM »
I have been curious over the years why I-Beam wings fly so well.  I wonder if the rib ridges and constantly changing airfoil has anything to do with it.  Planes that I have had that did not have LE sheeting but did have a top/bottom spar didn't do as well. 

Ken
AMA 15382
If it is not broke, don't fix it.
USAF 1968-1974 TAC

Offline Lauri Malila

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Re: Sheeted LE
« Reply #1 on: May 02, 2022, 12:03:35 PM »
It must be something else, like lighter weight, for example.
From purely efficiency-point of view, a smooth surface without rib ridges is clearly more efficient, at least in free flight. But maybe our free flight airfoils have more theoretical work behind them, and the more accurately you can build the airfoil, more probably it is that it works as calculated.
A better example may be the free flight stabs; A structure similar to I-beam (but with carbon tube spar) has to be 0,4...0,5mm thicker that a D-box stab with "same" airfoil to behave in same way. L

Offline EddyR

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Re: Sheeted LE
« Reply #2 on: May 14, 2022, 01:07:41 PM »
   Ken    I think with the power available back in the day more than likely the good flying ones were lighter than sheeted wing models.  Jack Sheeks told me most of his models were heavy and so the advantage went away. He flew two of my I beams and said they were much better than his. My cobra at 45 ounces with a ST/40  in it and some other long lost from memory model.
 Here is one thing I noticed when Bill Rich were flying together each week. His foam wing models would wiggle as they got near top of the wingover. I could see it in other maneuvers. The model was rotating in and out on the lines a very small amount. It showed up in the video's we did. The I beam models do not do it. I never built and I-beams larger than 610 sq". I built several foam wing models and I saw the same thing so I added very small fences on the flaps and the problem went away. Sheeted leading edge with ribs models do not seem to have the problem. I beam wings work good up to about 570 sq" and then any advantage seems to go away.  Back in the 1950's  I could frame up a I beam model in one day even with the slow glue we had.
Ed
Locust NC 40 miles from the Huntersville field

Offline FLOYD CARTER

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Re: Sheeted LE
« Reply #3 on: May 15, 2022, 02:33:11 PM »
Who has the proof that an I-beam flies better  (and what is "better"?).

If that were the case, then all the top "expert" flyers would be flying them.

Sounds to me like another "fable".  Someone started the rumor, and others took it as a fact.
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Offline Tim Wescott

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Re: Sheeted LE
« Reply #4 on: May 15, 2022, 02:52:11 PM »
Kinda tangential, but I suspect an I-beamer does better than something like a Twister because there's so many ribs, giving the airfoil significantly less spanwise variation.
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Offline Ken Culbertson

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Re: Sheeted LE
« Reply #5 on: May 15, 2022, 03:35:33 PM »
Who has the proof that an I-beam flies better  (and what is "better"?).

If that were the case, then all the top "expert" flyers would be flying them.

Sounds to me like another "fable".  Someone started the rumor, and others took it as a fact.
OR, built enough of both to notice a difference.  Only reason I stopped was the difficulty in finishing.

Ken
AMA 15382
If it is not broke, don't fix it.
USAF 1968-1974 TAC

Offline Air Ministry .

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Re: Sheeted LE
« Reply #6 on: May 15, 2022, 08:01:19 PM »
BOTH actually . ( trust the Canadians ) . !



the old farts into ' Tigers ' modelaeroplanely , prattled on re ' Flow Straighteners ' .

momentariilly digressing .!!!

https://www.aviation.govt.nz/assets/aircraft/airworthiness-directives/aeroplanes/dh82.pdf
RIGHT .

to get really tecnical . carbon fibre . as Id envisaged last century , for the ' skeleton ' ( Of  say a detroiter stunt airframe ! )
made off this & coverd in that plastic stuff as per combat wings , the G resistance would be astronomical . Or adequate , anyway .



To get totally awkward , the Junkers ' corrugated iron ' wings are a bit the same , aerodynamically . flying trashcans ! .  :-\



We'll  have you know , this is a MONOPLANE ! , if its monoplanes youre after .




Er . . . , wel . . .  A LATER ITTERATION .

Parently there was spare roofing at dessau ! .  :-X







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