That's the idea Matt. I can see the influences that are affecting you. Later, you'll look at these sketches, and be inspired to modify them more.

They look good, I prefer a little more of a slender fuse, but then I don't run a pipe. I do use a rear exhaust engine with a muffler.

Here's a project I'm involved in right now, to illustrate the process a bit.

The first iteration looked lean and mean in the concept stages.

Once I started working on it, I had to apply some aerodynamic rules. The design started to look "portly" to me. Here's where taking those art courses Denny mentioned comes to bear fruit.

It's getting there, and I believe the finished project will have much of the visual impact that the concept drawing does.

The first drawing is the concept drawing, the second is after applying some of the rules, then I realised that I needed more seperation between the wings.

Of course, mine are done on the computer, but what you are doing on paper is every bit as good.

As soon as I can convert my latest on this plane, I'll post where it's gotten to at present. This is not to compare our work, but rather to illustrate some of the design exercises one can go through.

Edit, I've conveted a couple of the drawings to jpegs.

The third one shows the portly, porky looking version when I increased the wing seperation. I felt that the fuselage had to also expand vertically, as the top wing being so much higher didn't look right.

The latest ,or last pic shows me trying to get the "look' back by changing perceptions. This is where that art training can help Matt.

So far, all I've done is changed the size of the spinner. This fools the eye, and makes the fuselage appear to be more in line with the concept sketch.

I'm considering making the fuselage wider so the design has balance, and appears more in proportion to the rest of the design.

These are the advantages of making sketches as you are doing. It gives you a direction, and a visual goal to shoot for.

Keep it up Matt. I think you may have a future in the best non-paying sport out there.

John,
Really cool bipe. i want one. Hey, you know there is a twin engined Stunter named Two Bits, Right?
Chris...

I hadn't really looked at the cowl much, but now I'm going to be looking at that cowl to see what you are complaining about...

I am talking about the up curve on the bottom front of the engine cowl on my Stoli Special. The curve on the plans was less aggressive but I thought it would look better. By making the curve up more aggressive than Rick drew, I made two mistakes:
1) While design numbers are Dave Cook's Lighning, the look was penned by Rick Campbell. Rick draws beautiful lines and by not following it, I made a messed up "the look". No one ever told me the model doesn't look good and I try to be objective and be happy with the look but I know the line is wrong and it glares at me every time I fly.
2) This one cost me several contest wins. By making the curve up too aggressive, I ended up with a small intake openning. Not enough air gets through to the engine which causes it to overheat and prevent any kind of consistent engine run during hot days. Another downside is the fact that the small openning gets blanketed by then nose on inside turns and causes the engine to overheat. if I wind them up too hard on inside turns, it takes too long for the motor to settle back to normal temps. Granted, the issue is non-existent if the temps are below 65 but that precludes any kind of summer flying.

I suspect the problem was not too small an opening, but too small an exit. If you have decent flow through the engine compartment you can get away with a very small opening, but you need air exhaust area at least twice as big as the intake. Three times is better. It creates a vacuum in the cowl and draws out the air.

Any ideas on how to open up a piped engine cowl so that there is enough air flow? Got pictures drawings? Anything!!! I don't want to loose Mass cup to Matt due to engine overheat! I'd rather make him work for it! I have no problem loosing when the other person outflies me but loosing due to things like a poor engine run absolutely infuriates me!

Last fall, I went through a lot of headaches to be able to go to Palisades Park contest. I really wanted to put my skills up against people we don't get in Massachusetts such as Mike Palko and Danny Banjock. I put up a practice flight 5 mintes before the official and when I launched, the engine overheated right away. A was so pissed at myself, I packed everything back in the car and went home. I don't want a repeat of this again!

Steve

Steve,

I think it was Frank Williams that had an article in Stunt News a couple of years ago outlining ways to cool an engine and pipe in a fully enclosed system. Small opening in the cowl for air intake and a huge opening over the pipe exit. The rest of fully enclosed and he had very consistent runs.

I have done this and it works. I've also had systems that had this with the addition of additional air intake directly over the front of the pipe (and the header connector) with another large exit just before the pipe tunnel exit. Really help with cooling.

Weren't you mentioning that you'd gotten your hands on a new motor recently, and wondering what to do with it?

Given that you're churning out these sketches, isn't it obvious?

Get thee to a drafting table, sonny!  Flesh those sketches out, and build a model to your design!

(Hint #1 -- I've been a professional design engineer for decades now, and the way to make successful designs is to boldly put in only as much new stuff as is really necessary, and to shamelessly steal the work of others for all the rest.  So for inner structure and whatnot, I suggest you find a model that you feel holds up well and is easy to build, and copy it within your external shape)

(Hint #2 -- cover it with all your leftover scraps of plastic film, or by whatever quick method you want.  Chances are you'll be cutting into it and changing things; when you're done fiddling with it you can strip it down and re-do it, or build new).

Get thee to a drafting table, sonny!

A drafting table?  Hey, we're in the 20th Century now. 

23 skiddoo.

I've always liked the look of Lambroghini's.  I think they just have a mean and aggressive look, and IMHO would make a good looking stuntship if restyled right.

I named it Reventon because it's the name of the Lambroghini I used for inspiration.

How did I do?

You go, Matt!

My new one will look more like a 59 Chevy Impala low rider.   

Howard,

>>A drafting table?  Hey, we're in the 20th Century now.  <<

Watch it, boy. Some of us still like putting pencil to paper.

Thanks Randy!

a 59 Chevy lowrider sure sounds cool!  No chance you could share that or is it relegated to secrecy in your skunk works! 

I came up with a minor detail idea this week (at work, duh!), that somebody might like. IF you have problems fitting a decent fuel filter into your cowl, anyway. My idea was to essentially run the fuel hose flush with the cowl surface (in a slot) and put as  big a filter as desired behind it...even one for an R/C car. Cover it with a scoop that's open on both ends, to camouflage it. Randy would probably stylize it with a widow's peak on the front and bifurcate the exit. Maybe some louvers over the filter? Ghost flames and pin striping to set it off... Steve

Matt,

Trust me, I design planes in my head all the time. Weird what may give you an idea.

I'm dating myself here (no one cares) but a long time ago Steve Allen hosted the Tonite Show.
One of Steve's many talents was "on the spot" song composition. He would ask an audience member
to play a few notes on the piano, and then compose a song around it, and give it a humorous name
(for copyright..).

It looked very difficult, yet some of the most unlikely inputs yielded good tunes. Evidently, the
challenge itself turned out to be a fine stimulus.

So what does this have to do with designing model airplanes? I'm suggesting that some novel
and interesting ideas might be spawned from a few nearly random shapes and lines, which become
a "theme" for a finished design.

To guide such efforts, I heartily recommend an article called "Design and Formation" by Claus Maikis,
which I had the privilege to transcribe for PAMPA Stunt News back in 1997 (I think). Claus is a
well known talented industrial artist as well as model airplane designer and flyer - one more Renaissance Man
in our hobby.

Claus' article discussed (with beautiful illustrations) how designs can incorporate themes: important information
for anyone desiring to learn to "design" themes for stunters.

Using a "Steve Allen" approach - taking inspiration from an almost random input might well result in
a fresh creative design. And we pretty well know how to "imprint" our theme or design on a practicable
stunter. We have easy access to the "numbers" associated with successful models. Styling can be less
constrained.

And we might well incorporate the newest "best practice" features to yield an excellent performer. Create
our distinctive styling around the well established technical mode.

Mr. Maikis and a dozen other superb designers and finishers (guys like Al Rabe and Randy Powell..)
show us everything from construction techniques to worthy paint and trim schemes.

With a winning design in hand, all that remains is to learn to FLY like these mentors! I left the hard
part for last..  ;->

A final attraction added to the rich set of technical and artistic experiences is simply "hanging"
with a diverse and interesting group of people. It's what keeps guys like me playing with CL Stunt.

L.

"Everything has been said, and we are more than seven thousand years of human thought too late." -Jean de LaBruyere

Larry,
When I was playing in piano bars, I would ask the pretty girls for their telephone number and make a song out of it. Actually it was easy to do. I had a LOT of fun!

This time I took the scientific approach with designing this stunter since I've read some of Ted Fancher's etchings about what to do when designing a new stunter.

If you ever have to do a year-long science project for school (like, if you go into aeronautical engineering and need it for a senior project), think about building a take-apart plane that'll let you swap wingtips and wings, and maybe even empennage.  Then do a series of experiments on how each change affects the handling of the plane.

If you go to someplace that does senior projects in teams (like WPI in Massachusetts), then maybe you'd have enough members on the team to do wind tunnel testing, to put numbers to the changes in "feel".  I think CFD is still fantasy for model-scale efforts like this, but maybe not -- computers just keep getting faster, after all.

U bet..."HEATED AIR...ALWAYS EXPANDS and that old speed demon rule...teenie cowling inlets and LARGE EXIT OPENINGS.

Not because the air expands.  Remember PV=nRT?  What were you doing during that class?




edited for assholicity

I didn't notice the "etc.", which I guess says to have a big tail.  A big tail allows the CG to go back, which reduces hinge moment (control load).  I thought you were referring to reduced hinge moment, the capablility to move the CG back, and drag as virtues of a low-aspect-ratio tail, which they are not: elevator hinge moment is approximately proportional to elevator area x chord.  Tail effectiveness is a function of size and shape.  (I can send you a spreadsheet that gives a better answer than tail volume, but is still easy to find the numbers for.) Textbooks say, for good reason, that you can ignore stab drag for stability purposes.  I have been pestering people to explain why they use low-aspect-ratio tails, because I am planning not to do so on my new dog.  I haven't read Ted's article, so I was curious as to what it said.

Using the aforementioned spreadsheet, I figure that the tail on my current airplane is 82% as effective as a standard Impact's.  The one I intended to put on my new dog would have been about 113% as effective as a standard Impact's tail.  However, I sanded the tips backward: roundy at the TE and tapered toward the LE.  This wouldn't have fit the elevators, so I recarved the tips, reducing the aspect ratio and reducing the tail effectiveness to 106% of that of a standard Impact.


Best I can figure, a low tail aspect ratio gives a stiffer tail, which is good.  Also, a large stab chord makes the Reynolds number higher, which could keep the laminar-turbulent transition point from misbehaving, if I correctly understand Igor.  

That would be good, but as you know, it's hard not to stray off the path.

Curls?

Back in about the mid '70's I built this huge 6 foot span stunter powered by a Taipan 61 that I used to fly at Moorabin airport with Peter White and the rest of the mob. It was a handfull so I fitted boost tabs to the elevators in an attempt to ease the loads. I got the idea from a large RC aircraft I used to work on at Woomera...the Jindivik .