Design > Stunt design

Design by Committee

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Jim Pollock:
Ted, and Everyone else too

Here is what I propose.  I have a basic sheeted SV-22 foam wing, with 4 inch bellcrank assembled with 1" flat tips, like Brett's Infinity.  Let's design the rest of the plane  including the flaps with the following basic information.  Power system is a rebuilt PA-61 RE with a Hi-Tourque pipe.  The wing does not have gear blocks installed. The airplane will probably utilize a Carbon Fibre Landing Gear.    ???'
 

Questions.  Percentage of flap to that of the rest of the wing?
                   Acceptable nose and tail moment arms?
                   Percentage of Stab/Elevator area to wing + flap area?
                   Percentage of Elevator to total Stab/Elevator area?
                   Fuselage ease of construction and asthetics(sp?)
                   Target design weight?

Alright let's begin..... The rest of you on the forum are the design committee!
Ted is the committee chairman.

Lastly,  Ted, are there any other questions that you would like to add to the basic premise?

Jim Pollock,
AMA 68146
                   

Ted Fancher:
Hi Jim,

Cool idea.  I'm going to be monitoring the input and will try to keep from throwing too much in right away.  I think that will generate a lot more input than the other way.  Right or wrong (and believe me, I'm not any rocket scientist on this stuff) when somebody with a bit of a record of success expresses a point of view on this subject it tends to get accepted as gospel and discussion breaks down.  Ergo, I'll keep a bit quiet until there's been some discussion already. 

What I will promise to do is to step in with an opinion if I see something gaining momentum which is out of step with my understanding of how these things work.

My only comment at this point would be to start with a realistice assessment of what weight you're likely to be able to build this critter.  Everything else has to pretty much evolve from that prediction.  Be really critical and honest about past performance (your own at the building bench) and work from that premise.

The other thing you need to do once that is determined is figure out how much area you've got in the existing unflapped wing so you can make a determination of what you'll need to do in terms of flap area and movement to handle the weight.

One final clue, you've probably read enough of my ramblings to realize that, while I think stunt ships should be as light as you can reasonably make them, I'm not one that thinks missing a target weight is an automatic disqualifier for a good airplane (Lord knows, I've played that game over the last fifty years!)

Ted

Bill Little:
Hi Jim, Ted,
I would expect you can easily build a plane this size at 62oz, Jim.  If you agree, that gives you a point to start from.

 

Randy Powell:
>>Be really critical and honest about past performance (your own at the building bench) and work from that premise.<<

Wish I had some sort of consistent benchmark to draw from. I seem to build an insanely light plane followed by an unacceptably heavy plane, followed by a very light one...ad nausium.

The Cobra I'm building looks to come in under 40oz. The new PA plane (at 740 squre inches) also looks to be quite light, coming in at under 55oz. But the plane I built last winter was a real pig. And the one before that was no lightweight. I don't see that my building practice is much different from plane to plane.

Hmmm...Maybe it's those helium tanks I just had refilled... :-X

dirty dan:
If you are going to key off Brett's Infinity, calculate the fuselage side area he used and increase it at least by 25%.

Other than the above piece of advice shrewdly arrived at, I'll be merely following along. My only claim to fame when it comes to "design" is that I have not yet thoroughly ruined Mikey's SIG Skyray 35 design, although the second of three models built might still prove me wrong.

Dan

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