An Interseting Idea...?

{It seems the edit function won't let me change the
mis-spelling in the subject line even though I
was logged on.}

...or a really dumb idea? I just read the article about
the "Doctor" and am thinking about airfoils and flaps. I have a
Sig Twister which I am just beginning to build. I am planning on
lengthening the fuselage as in the Fancherized version (thanks
to everyone who responded to my previous post on that question).
The Twister has a thick airfoil (22% I believe), and I am
thinking if I built the wing making the leading edge more blunt
than shown in the plans and glued the flaps on stationary
I could get a wing *similiar* in lift characteristics to the
Doctor or Medic without the extra problems of trimming involved
with flaps.

Before responding, some background: I have been flying for only
1 year, and at this point am not looking towards flying
competitively. I am merely a sport, or "Sunday" flyer or
whatever you want to call it. But I do want to learn to fly
the full pattern. All the planes I have flown so far have
been of the "old-fashioned" style, i.e. fixed leadouts,
fixed tip weight, rudder offset, unflapped. As such, they tend to
have outward yaw. They fly *OK* but need faster lap times
than the "accepted norm." My intent was to build the Twister
with adjustable leadouts, a weight box, and no rudder offset.
After reading the "Doctor" article, I realized it might be
better to learn how to trim an unflapped plane really well
first before jumping all the way in and trying to trim a
coupled-flap stunter with all the extra variables involved.
The obvious answer is to build a Doctor or Medic, but 1) I'm
still in the kitbuilding stage & don't know if I'm ready to build
cutting all my own parts; and 2) I already have the Twister.

So what I'm wondering is do you think the Twister will
fly ok with the flaps left stationary at a 5.1 to 5.2 second
lap time? Would a blunter leading edge be of any benefit?
Or is it just a dumb idea? If so, forgive my ignorance.
Sorry for the length of this, and
thanks in advance.

Perhaps I should elaborate for those who haven't read the article.
To Summarize:
Flaps aren't necessary to generate lift, but they
increase lift for a given wing loading, allowing a higher
angle of attack before a stall happens. A blunt leading edge
on a non-flapped wing allows the stagnation point to move
further before a stall occurs, also allowing a higher
angle of attack. Increasing speed also increases lift, but
then your lap time gets too fast.

I'm in a similar position except that I am building for .25 engines.

Rather than mess with the Twister, why not build a Doctor and save your Fancherised Twister for a bit later?

This will probably date me, but I recall an old article from "MAD" magazine (60's?) where it starts out showing you how to alter a screwdriver into an awl (because you need an awl but don't have one), and then some other tool into a screwdriver, because now you need a screwdriver....and so it goes on until finally you need to convert an awl into replacing the previously altered tool.

Getting back to your problem!!!
The 35 Skyray builds fast and is pretty tough. As I mentioned last night at the Tree Town Club meeting, I would also build a simple half-a (Skyray of course) and get over the inverted crashing with that plane. They just bounce better. You can use 42 foot lines to slow it down a bit , since you are using the Norvel engine.

If you do
>something that hasn't been done
>before, you might have a
>good airplane, and you might
>not. Experimenting is fun,
>too.

Part of the problem is, like me, one may not really have the evaluation and trimming skills to realize the difference!

FWIW

>
> ... I have a Sig Twister which I am just beginning to build.
>I am planning on lengthening the fuselage as in the Fancherized
>version (thanks to everyone who responded to my previous post
>on that question).
>
> ... if I built the wing making the leading edge more blunt
>than shown in the plans and glued the flaps on stationary
>
You'd have a plane that would be a lot of fun to fly!
>
> ... without the extra problems of trimming involved with flaps.
>
The Magician design was created with the intention of duplicating the flying characteristics of a Nobler in a simpler package. It is/was very close to the size of the Twister (actually vice versa since the Magician is the older design, circa 1957 or so). Flaps on the prototype design were fixed, not coupled. It is my opinion that the Magician's tail is definitely way too short for good performance with coupled flaps.

> ... I do want to learn to fly the full pattern. All the planes
>I have flown so far have been of the "old-fashioned" style, i.e.
>fixed leadouts, fixed tip weight, rudder offset, unflapped.
>
> ... My intent was to build the Twister with adjustable
>leadouts, a weight box, and no rudder offset. After reading
>the "Doctor" article, I realized it might be better to learn
>how to trim an unflapped plane really well first before
>jumping all the way in and trying to trim a coupled-flap
>stunter with all the extra variables involved.
>
> I already have the Twister.
>
>So what I'm wondering is do you think the Twister will fly ok
>with the flaps left stationary at a 5.1 to 5.2 second lap time?
>
>Or is it just a dumb idea? If so, forgive my ignorance.
>
I love the idea. But go all the way. Build two. Copy all of the parts and build one the way Ted suggested, and the other the way you are considering now. The tail will not need any added length with fixed flaps, but the turtle deck add-on to inrease rear side area is still valid, as is the larger, thicker stab and elevator.

Kiwi

You've gotten a lot of good suggestions, any of which aren't unreasonable to get yourself going with a stunt pattern capable ship. I truly don't have a lot of problem with any of the suggestions you've received.

What I'd like to add to the mix is that at this particular stage of your stunt "career" you might just be getting way too deep into the design criteria and a lot of minutiae that probably isn't really germane to you.

Until you get the basic "tricks" to the point of personal comfort, the particular design simply isn't all that critical. In support of the DOCTOR article, I do consider a flapless ship desirable for the simplicity of trimming aspect. For that reason I encourage you to either scratch build a DOCTOR/MEDIC or buy a SIG Skyray kit. Either will simplify the learning curve which is really important...learning to trim an airplane to its maximum capability.

I won't reiterate the discussion of flapped versus flapless designs from the DOCTOR article. Suffice to say that building a simple, capable flapless ship and powering it with a trouble free and predictable powertrain like an OS .25FP or .25LA will greatly simplify the learning curve for basic controline aerobatic flight.

Sure, slightly better performance is available from more sophisticated, flapped stunters with high zoot tuned piped power trains, but...at this stage you couldnlt tell the difference in the air and the number of pieces at the end of a "mistake" is substantially greater.

Bottom line, if you wish to build the Twister without flaps, go ahad and do so. It'll be easier to trim to your current state of flying skill. Paul Walker or Bill Werwage might prefer a more sophisticated package...but, they ain't flying it.

This weekend, I was watching someone flying a Banshee, and it
was turning so smoothly & "fluid," I've decided to make the
flaps on the Twister working as per the plans. In fact, I
hinged them yesterday. I'll just take my chances with
trimming it.

I probably will build another with stationary flaps just to
compare, or else build a Medic.

Or if I have a really hard time trimming this one, then maybe
glue the flaps stationary & remove the linkage.