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Author Topic: High Wing Stunters  (Read 7588 times)

Online David Hoover

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High Wing Stunters
« on: January 01, 2015, 07:09:19 PM »
Tim Wescott's threads on his Test Pig #3 got me thinking about high wing stunters.  I know that there have been a few, Boxcar Chief comes to mind and someone mentioned another design in one of Tim's threads.  The control line PA plane has evolved into the thrustline-above-wing-stabilizer-slightly-above-thrustline arrangement that we all know and love and sort of understand (some more so that others) but what happens when you move the wing up above both the thrust line and the stabilizer?  Based on the lack of competitive plane with this arrangement I suspect nothing good but I'd like to hear some explanation of the effects from the people who know.
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Offline Howard Rush

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Re: High Wing Stunters
« Reply #1 on: January 01, 2015, 08:38:18 PM »
Basically what you have in a normal CLPA model flying upside down all the time when upright.

That's an interesting way to look at it. 
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Offline Igor Burger

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Re: High Wing Stunters
« Reply #2 on: January 02, 2015, 01:40:26 AM »
Basically what you have in a normal CLPA model flying upside down all the time when upright.  

right  ;D ... however only in case that you have landing gears on opposite side ... so it can counterbalance mass of fuselage under the LO guide  VD~


Online David Hoover

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Re: High Wing Stunters
« Reply #3 on: January 02, 2015, 08:33:31 AM »
right  ;D ... however only in case that you have landing gears on opposite side ... so it can counterbalance mass of fuselage under the LO guide  VD~


But doesn't positioning the LO guide on the vertical CG take care of this?
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Offline Igor Burger

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Re: High Wing Stunters
« Reply #4 on: January 02, 2015, 09:11:48 AM »
it does, and that is the problem, there are several things comming to formula, one of them is CG position relative to LO, so wing under the CG of fuselage balanced by landing gears leads to wing under the fuselage center ... that wing position and its drag plus landing gears drag makes negative pitching moment which is balanced by pitching moment of _classic_ (= tractor = CW = righ hand) prop moment pitching fuselage UP ... means classic stunter as we know it is very well "debugged" thing comming from 50+ years experience :- ))) ... change something and you will come to troubles :- )))

Online David Hoover

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Re: High Wing Stunters
« Reply #5 on: January 02, 2015, 01:06:09 PM »
... change something and you will come to troubles :- )))

That's what I suspected which is why I asked the question.  From what you said I take it that a prop rotating opposite to the usual direction of rotation may be of some benefit with a high wing?
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Offline Tim Wescott

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Re: High Wing Stunters
« Reply #6 on: January 02, 2015, 01:35:02 PM »
one of them is CG position relative to LO

Do you mean CG position relative to LG?

Test Pig #3 flies at least as well as a Skyray but for some quirks which I think are unrelated to the wing position.  In order to get it to work that way, I had to suspend the leadouts below the wing by about two inches.
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Online Dave_Trible

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Re: High Wing Stunters
« Reply #7 on: January 02, 2015, 02:11:49 PM »
Tim,  pretty sure Igor was referring to VERTICAL CG relative to lead out position.

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Offline Igor Burger

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Re: High Wing Stunters
« Reply #8 on: January 02, 2015, 02:38:18 PM »
Tim,  pretty sure Igor was referring to VERTICAL CG relative to lead out position.

Dave

yes, exactly

Offline Igor Burger

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Re: High Wing Stunters
« Reply #9 on: January 02, 2015, 02:47:02 PM »
That's what I suspected which is why I asked the question.  From what you said I take it that a prop rotating opposite to the usual direction of rotation may be of some benefit with a high wing?


welll I would say it diffferent, if you want use pusher, may be you will do smaller mistake if you have inline design or even wing little higher ... but I do not think you can do solution without compromises (or minimal compromises) with one prop solution - the best will be 2 contra props on one shaft, but that is another story

I designed Max Bee so that it has LO guide little under CG (so it hangs out of the circle on lines), it helps in some situations, but usage of pusher on such desingn gives visibly worse result ... several guys reported the same after testing pushers, pushers are better usefull on inliners, so I _think_ wing LITTLE over centerline could be also well usefull with pusher

note: that all expects that LO guide is in wing tip

Offline Tim Wescott

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Re: High Wing Stunters
« Reply #10 on: January 02, 2015, 03:16:27 PM »
Tim,  pretty sure Igor was referring to VERTICAL CG relative to lead out position.

Dave

D'oh.
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Offline Tim Wescott

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Re: High Wing Stunters
« Reply #11 on: January 02, 2015, 03:19:32 PM »
note: that all expects that LO guide is in wing tip

I think that if you're going to do a high-wing stunter without anhedral to bring the tips down, you pretty much need to hang the leadouts underneath the wing.

But Igor's comment about his LO placement makes me wonder if one's adjustable leadout guide on a regular stunter should go up and down, as well as fore and aft.  Hmm...
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Offline Trostle

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Re: High Wing Stunters
« Reply #12 on: January 02, 2015, 05:58:47 PM »
It would be interesting to hear from those who have built a serious stunt ship with the wing noticeably above the thrust line.

One in particular is the Hi Boy by Ted Goyet and Bob Palmer published in the 50's.  (It is OTS legal by the way.)  Floyd Carter has built a nice one but I have not heard how well it flies.  The thing has the bellcrank in the wing and the leadouts coming out of the tip.  Has flaps.  Bob Palmer remembers that it flew with the outboard tip up due to the vertical CG being below the leadout position.

There have been other published designs:

Vic Macaluso had a neat F-8 Crusader.  The wing root was not that much above the thrust line (may 1/2") and th wing had anhedral, so the leadouts were below the thrust line.

Dick Mathis did a neat looking profile of the Citabria.  This has the areas and moments for a nice 50" span 450 sq in plus stunt ship with no flaps.  The wing is 3" above the thrust line, it has dihedral (1/2" under each tip) and the bellcrank/leadouts are in the wing.  His article states that he found no adverse problems with the high wing, claiming the performance was somewhere between that of a Magician and the Midwest WW II series.

Walt Musciano did a mostly scale Spirit of St Louis.  (symmetrical wing section, and a slightly enlarged horizontal tail)  Bellcrank is in the fuselage with the leadouts suspended below the inboard tip.  I built one for OTS.  It flies a "respectable" OTS pattern when there is very little wind.  It is "challenged" primarily because of its size and less than desirable wing loading.  No problems with the high wing.

Keith


Offline Jonathan Chivers

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Re: High Wing Stunters
« Reply #13 on: January 03, 2015, 07:19:33 AM »
Hi,
I am playing with plane design and like the visual aspect of a high wing design, but have come up with an odd consequence, that is the position of the control horns for the flaps and elevator.

If the wing is positioned near the top of the fuselage, then to avoid the control horn sticking out of the top of the plane, the control horn needs to be below the center line of the wing. This then forces you to have the control horn for the elevator about the center line of the stabilizer. This implies either a very low stabilizer/elevator or a hump above the stab eating into the rudder space.

Does anyone know a way out of that AND keep the elevator control mechanism within the fuselage?

Jonathan

Offline Tim Wescott

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Re: High Wing Stunters
« Reply #14 on: January 03, 2015, 09:01:28 AM »
Sure, Jon -- either make a bellcrank that takes flaps and elevator off of opposite sides of the pivot, or have a bellcrank in there someplace that reverses the motion to the flap or elevator.
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Offline Howard Rush

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Re: High Wing Stunters
« Reply #15 on: January 03, 2015, 10:51:12 AM »
Does anyone know a way out of that AND keep the elevator control mechanism within the fuselage?

Sure.  Put a pushrod on either side of the bellcrank: one to the flaps, and one to the elevator.  I'm doing something like that on my new dog.
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Offline John Kelly

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Re: High Wing Stunters
« Reply #16 on: January 03, 2015, 12:05:59 PM »
   ...Hey Jonathan, Do it like the " HI BOY " ( two armed bellcrank ) .  Cheers,  John
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Offline Howard Rush

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Re: High Wing Stunters
« Reply #17 on: January 03, 2015, 12:48:27 PM »
What has been will be again, what has been done will be done again; there is nothing new under the sun.
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Offline Jonathan Chivers

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Re: High Wing Stunters
« Reply #18 on: January 03, 2015, 02:37:28 PM »
Thanks guys, overlooking the obvious strikes again. Such an obvious and simple answer.

Jonathan


Offline wwwarbird

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Re: High Wing Stunters
« Reply #19 on: January 07, 2015, 07:53:00 PM »
It would be interesting to hear from those who have built a serious stunt ship with the wing noticeably above the thrust line.

 Here's one where the wing, stab and thrust line are all exactly in the same line. With the leadouts set properly in relation to the vertical CG it performs as a full-blown stunter and is dead stable everywhere. y1
Narrowly averting disaster since 1964! 

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Offline Don Hutchinson AMA5402

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Re: High Wing Stunters
« Reply #20 on: January 08, 2015, 11:11:45 AM »
Here is the Cub. One of the Warbird series. N number same as Dake Gleason's full size Cub. As one can see, the bellcrank is mid fuselage and leadout guides to suit. The bellcrank is cruciform, (two output arms) the inside pushrod goes to the elevators and the outside rod goes to the flaps. 

Offline Don Hutchinson AMA5402

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Re: High Wing Stunters
« Reply #21 on: January 08, 2015, 11:18:58 AM »
Couldn't get this photo on the first message so here it is.

Offline Tim Wescott

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Re: High Wing Stunters
« Reply #22 on: January 08, 2015, 11:58:02 AM »
Couldn't get this photo on the first message so here it is.

That's because they're monstrously big files, and you have a 1GB limit per posting.  If you have photo-massaging software you can make it smaller or at least lower the resolution.  (Note the sizes of these two files).

I try to keep my pictures at 640x480 or so, to keep from using too much of Sparky's disk space.
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The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.


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