I am going to take one more try at this

[Mike Griffin]

Over the years model airplane design has evolved like most everything else.  Somewhere, some one in the beginning had to come up with what would fly well and put it all together and say "Here is a good flying stunt plane and I made it."   It would seem to me there would have to be some kind of formula that would have to be followed in designing a model that will fly well…I am not talking about cosmetics I am talking about dynamics, measurements and placement of parts… lets just imagine for a moment that I have some sort of shape in mind for a wing, fuselage and tail.  Lets also imagine that I have no access to plans of previous stunters.   I think I want a wingspan of  56 inches and an idea of a shape for that wing.  Now where do I start to make sure this plane is going to fly well.  If I make the span 56 inches does that dictate that the root chord and tip chord have to be known in order to get the proper wing area or is there a given proper wing area for a span of 56" that somebody came up with along the line of evolution?  What dictates the length of the fuselage and area of the stab in relation to the wing?  Should the Wing and stab be in line with each other or offset?  Where is engine location in relation to where the wing and stab  are located.

Where is the starting point and does  that starting point dictate the rest of the dimensions on the plane?  If so what are the formulas you have to know.  Is it a domino effect…if A is a given, then does B depend upon what A is and does C depend upon A & B or Just A or B?

Maybe I am not asking the question right but I wanted to take one more shot at this before I gave up.  Sure I can take all the plans I have and pick a wing and a fuselage and and a tail and put them all together and call it "The Flying Wonder" but the only difference would be in appearance.  A few years ago I kitted a design called the AIRBENDER.  I stole the name from a movie and  It had the fuselage and tail of  Jean Pailet's Zephyr and the wing of Allen Brickhaus's Encore.    All I did was plagerize two different designs and put them together and called it something new when actually there was nothing new but the look and it flew really good.

So in the beginning, who determined how a stunt ship should be built?  Did they just guess and say..."tell you what, lets make the wing this long and this wide and stick it about in the middle of the fuselage body and I would say we should make the fuselage ...oh I don't know....how does 39 inches sound?  Yeah lets do that....." is this how stunt ships evolved?  Trial and Error?  Or was there some engineering that had to take place?

[Mark Scarborough]

Mike, one of the reasons you cant get the answer you are after,,
it was an evolution, if you look at all the plans for stunt planes from the begnining,,( you know the ones you dont have) you can see the evolution

bottom line, there are such subtle differences in most of the top designs,, you can make the case that pretty much they are all related,,

a stunt plane is a compromise of ideas, a SYSTEM that each change affects a change on another ,, and so on,,
I tried going down the path you are headed on,, bottom line, take a design that is close to what you are thinking of,, and modify it, essentially even if you start with a blank page, ultimatly you will be replicating the basic layout from something else,,

I think the Mr. Fancher in one of his articles for Model Aviation did a write up with a bunch of formulas and numbers to give a basis for design,, but,, well unless you really want the purity of "completely designed by me" ,, well, there just isnt that much variation,,

[Tim Wescott]

No product design team that I've ever worked on tried to do absolutely everything new -- they always based their designs on previous products of their own companies or others.  In other words, they shamelessly copied.

Furthermore, every really successful product design I've ever worked on had a project manager or technical lead who tried to minimize the number of innovations introduced in any one product.  Every new thing you do is not just an opportunity for success -- it's an opportunity for failure in unexpected ways.

If you look at the old stunt plans, you'll see the evolution of the modern stunter -- here's a rich source of plans to contemplate: http://www.outerzone.co.uk/index.asp.

If someone did give you a set of guidelines, it would just be how to draw a plane that's a copy of one top plane, or an average of several.

The way every good design engineer that I know gets designs done is by (a) finding a design to copy, (b) analyzing everything about that design, getting into the original designer's head and figuring out why it was done (or if you're lucky grilling the guy), (c) deciding on a limited set of aspects of the design to change, (d) making the changes, and (e) synthesizing the design into a whole.

There's really not an 8-1/2 x 11 sheet of paper with a set of simple equations that Paul Walker, Igor Burger, Bob Hunt and all the other top guys trade around while snickering about those of us who aren't in the club.  Rather, there's a bunch of guys who have a feel for how changing an aircraft design will change its performance, who start with a familiar design and tweak it, and then do it again.

If you read the design articles of the top guys, you'll see that the planes that they're flying are each at the end of its own set of evolutionary development (and then later you'll see that it was just the middle).  If there were a firm set of rules, that wouldn't happen.

So, I think you're asking for something that does not and cannot exist.

[Howard Rush]

Yup.  I think people just fiddled until they got the characteristics they wanted.

[Dick Pacini]

Jack Sheeks told me back in the 60's that moments of 9 1/2, 10 and 14 were a pretty good start.  I think the earlier Nobler is close to that.

[Howard Rush]

Jack Sheeks told me back in the 60's that moments of 9 1/2, 10 and 14 were a pretty good start.  I think the earlier Nobler is close to that.

Or copied "numbers" that have no physical significance and have names that mean something else. 

[Dick Pacini]

That advice was given to me almost 50 years ago.  Lots of things have changed since then.  I wouldn't consider those numbers gospel today.

[Allen Brickhaus]

Bill Netzeband published a column in Model Airplane News on an "average" model.  Does anyone have a copy of that or what month and year it was published.  At least 12 to 20 models of many different "numbers" were averaged for the 35/40 sized set of numbers.

Allen

[john e. holliday]

Mike if you want to be different, go look at what Bob Baron and Bill Netzband did in their day.   They had some strange in away stuff that did the pattern they way they wanted.   When Bob finally won the NATS it was with a proven design by Big Jim Greeneway(spelling).   If you look at Jack Sheeks designs they were very similar with out lines being changed to represent what he wanted.   Each of the top designers has what they think works for them with minor changes as it goes along.   Another one to check is Bobby Hunt and the evolution of planes he has designed and published.

[Avaiojet]

Maybe I am not asking the question right but I wanted to take one more shot at this before I gave up.

Mike,

Why would you want to give up before you even start?

You want to reinvent the wheel, just go ahead and do it! It'll be fun!!

I've been working on this unusual project from time to time. Had it up and did a bit just a week ago.

Doesn't look like a stunt ship but it will stunt. How well is the question?

Sure it's a copied model of a great tested design, but changes have been made. CL is different.

Nothing wrong with trying new things.

Starts with an idea then a line. I'm sure you're thinking about something? Draw that first line!

You may want to find an inexpensive CAD program to help with your drawing, and possibly, pick up a book

about "Simple Aerodynamics," which should be helpful when plotting your CG. All the math you need will be there.

Best of luck!!

Charles

[Doug Moon]

.......So in the beginning, who determined how a stunt ship should be built?  Did they just guess and say..."tell you what, lets make the wing this long and this wide and stick it about in the middle of the fuselage body and I would say we should make the fuselage ...oh I don't know....how does 39 inches sound?  Yeah lets do that....." is this how stunt ships evolved?......

Yes this is how stunt ships evolved, near as I can tell.  I urge you to get or find the Tom Morris published book of OTS and Classic Plans.  Look at the years of the published models and you can follow the evolution of how the design of the stunt plane came to be.  Incidentally there are some really odd OTS designs out there, they are awesome at the same time.  It shows what people were trying and having fun with in the beginning.  Some guys would try anything!!  

Look at the cover of SN, that is no stunt plane of today but it is a start for tethered flight.  From there it all goes in many different directions.  But once a known "area" of numbers gets out in the community that is good working envelope for type performance and flight that is wanted/needed you will see a trend in that direction.  

On another note, before you start your design you need to know what type of power train you intend to use.  This will answer about 90% of your design questions as far as where to put the thrust line in relation to the wing and so on. (I saw that on your other thread)  Then it just fine tuning what you want it to look like.  You said you have a bunch of plans.  Once you know the engine you are going use pull all the planes out for that type and size motor.  Start measuring and see if you can find a trend.  Work in that area and make some changes, slight, to make it your own.  It will be your model but you will know you are in the performance window and you should have good success with it.  Otherwise its just cut and paste.  And we all know time is not something we all have endless amounts of so wasting it on something that has already been tried and didn't work is no fun and not worth it.  Then once you build your plane and fly it you can make assessments from there as to what needs to be changed from the actual in the air performance.

[Larry Renger]

The real trick is to figure out how to make whatever you build fly right. Take a look at my avatar, the Sky Streak. It stunts very well indeed. Smooth, but maneuverable. The key was to find the correct balance point, handle spacing and elevator throw.

As an anecdote on the subject, Eric Rule (RSM) got a call from a customer lauding the performance of his profile P-40. The guy asked what the "numbers" were. Eric told him, and the guy replied "that can't work!"

There is one in every crowd. 

[Eric Viglione]

One of the things I think could be fun, is re-visiting older designs that may have been abandoned for lack of trim knowledge, adjustable technology or power packages available at the time. How about an electric flying wing type design, heck, go rudderless and throw a little electric on the wing tip at a 10Deg offset and do bi-slob style stunt, I dunno, if you wanna do something different, decide on what kind of different you are shooting for.

If you are looking for something that does the AMA Open Stunt pattern as close to rule book as possible, well, that particular set of parameters is pretty well established, with only a few design philosophies seperating the top performers, and most of those boil down to personal preference and flying style. If you just want something that looks different than a Nobler but flies like a Nobler, look at the designs of the day that were succesful. Tucker Special, Chizler, etc. They all look very different than a Nobler, but you start comparing aspect ratio's, airfoils, wing area, tail volume, moments, etc. they all start to blur.

Just as a fun experiment, Take any given plane, say an Oriental, take the canopy, change it to a small open cockpit, move it to just in front of the tail, and change the rudder shape, and you have an old racer look, move it forward, right up to the spinner, and put the canopy on backwards, trim it down and give the rudder a jet treatment and sweep back the wing tips, keep the flap  & elevators area the same and sweep to match. You can do all kinds of things that will change the look and keep a lot of the flight charecteristics, and may improve some, and make some a whole lot worse, but it will be fun trying, heh heh. That is really just cake decorating, not really any kind of new ground breaking design technology, but it can yield pleasing and sometimes surprisingly good results.

EricV

[Tim Wescott]

What Eric said, except look at those old designs that are still being used -- picking through plans, I find designs that were ten years behind their time.

It would be nice if there were guidelines about what's going to change when you make substantive changes to the aerodynamics, like changing the tail moment arm, or changing the flap area, or changing the flap-elevator ratio, or the aspect ratio, or whatever.  And there are!  Just read every post in this group, going back several years, and decide who to believe.  (I tend to believe those who I see scoring high in the contest reports, and to some extent those who seem to really speak from an engineering background and don't just emit techno-babble.  But then, I'm a design engineer, if in a different field, so that's naturally who I'm going to trust).

[Brett Buck]

One of the things I think could be fun, is re-visiting older designs that may have been abandoned for lack of trim knowledge, adjustable technology or power packages available at the time.

   Oh, you want an event like that?  We have one, its called Classic!

    Brett

[Eric Viglione]

Brett, I'm the LAST person who would suggest a new event!!! I like what we have now just fine and feel we barely have enough volunteers to staff what we do run. I believe this thread started as a design question, not an event question.
(You pot stirrer, LOL!)
EricV

   Oh, you want an event like that?  We have one, its called Classic!

    Brett

[Brett Buck]

Brett, I'm the LAST person who would suggest a new event!!! I like what we have now just fine and feel we barely have enough volunteers to staff what we do run. I believe this thread started as a design question, not an event question.
(You pot stirrer, LOL!)
EricV

   Missed my (comical) point  - you described the current situation in Classic to a tee.

   Brett

[Randy Powell]

Trust me Mike, there is a design window that have evolved over many years. You stay in the window, the plane with fly and fly competently. Certain design features will effect certain areas (more wing area, more lift. Bigger flaps or smaller flaps, different effect and so forth), but all within a certain window. You go outside those parameters and what you get is some things might get better but others will get worse. You give something up to get something.

I spent several years designing high aspect ratio planes. The did some things extremely well (like turning corners) but at the cost of other things. I went pretty far outside the envelope with some aspects of the design (pun intended) and got very interesting results. I learned a lot about what made things go. I tried a long time to mitigate the things that these designs did poorly while trying to retain the things they did well. But what I ended up with was a design that was back in the window. Very smart guys over a long time figured out (whether by math or trail and error) what would work without giving up too much.

[Mark Scarborough]

Mike,

Why would you want to give up before you even start?

You want to reinvent the wheel, just go ahead and do it! It'll be fun!!

I've been working on this unusual project from time to time. Had it up and did a bit just a week ago.

Doesn't look like a stunt ship but it will stunt. How well is the question?


Best of luck!!

Charles

Charles, to be clear,, there is a HUGE gap between a model that will fly a few simple loops,, and a model that is capable of competitively flying the stunt pattern
as a general rule, when WE talk about a stunt model, its a model that will competativly fly the pattern, NOT a model which is capable of floundering through some manuevers
there is room for both in this hobby, however, lest some misconstrue the direction of THIS thread,, its about STUNT models, not models that will do a couple sort of tricks,,
thanks for listening?

[Dave_Trible]

Mike,  the way you titled your thread made me wonder if you meant you would try designing one more time or pry some secret formula out of someone.  If the latter is true then I must tell you there really isn't a secret potion, diet pill, magic bullet or Indian rain dance.  Just years of working the stuff to suit the individual. Within boundaries many things work.  It mostly about discovering where the red lines are and not cross them.

Dave

[Serge_Krauss]

Mike-

I fell down on the job. I've been quite busy with other things and have been off the forums for some time. I really did start with a quite lavish intro for you that was difficult to compose because of just what the guys here have been saying. Design does depend a LOT on what others have discovered by experience and evolution. That having been said though, it is indeed possible, with certain things that have been learned, to design a plane from scratch that will fly well at the intended goal - better than just throwing the dice, and as well as just copying.

Your  domino effect is not far from the mark, and I did indicate to you a sort of flow-chart outline that works. However, there are branches in the road. You can start with any parameter that you are set on achieving - like span, if you like - but power plant or wing area are more common (these all concern weight/wing loading and span loading, which lead to other choices, each of which have defined purposes). I mean, you may want something that fits your car, something for a favored engine, something for sport flying, something to deal with gusts, something for top competition, something to suit a budget, etc., etc. But the design parameters are all interrelated.

I will send you what I have done so far, even though I think that it is more complex an intro than the actual design sequence and techniques I'll introduce. I don't want it to scare you off, because my intention has been to actually create something that you can follow, right down to the math techniques, when necessary. Yes, there are a set of well-used, standard "formulas" (relatiobnships), but they can be handled. The last things that I'd gotten to in my little "exposition" were unfinished and not placed in their explanatory context. You'll see.

What this boils down to is that, unlike some other pretty excellent minds and modelers here, I think I can actually answer this question adequately and have this confidence based on quite a few years as a pretty good teacher of these skills. I'm sorry to have put you on the back burner so long and understand your frustration! Look for my e-mail in the next few minutes. - SK

[Mike Griffin]

I truly appreciate all of the input you guys gave me on this thread.  I was and am interested in how, over the years, we have arrived at where we are today.  Lord knows I cannot even come close to the the brilliance of some of the pioneers of design who got us to the point of where we are today in stunt design.   I still wonder if you took all of the great designs we have today say in a .40 - .46 size stunter and started comparing the numbers, if a common formula would start to emerge so that we could have a "general" rule of thumb formula?  Numbers that were close that they all shared in common so we could say we have a general guideline.  That of course would be a monumental task to undertake if you really wanted to be thorough.  In any case, thanks for your patience guys in helping me learn something I was very interested in.

Mike  

[Tim Wescott]

What this boils down to is that, unlike some other pretty excellent minds and modelers here, I think I can actually answer this question adequately and have this confidence based on quite a few years as a pretty good teacher of these skills. I'm sorry to have put you on the back burner so long and understand your frustration! Look for my e-mail in the next few minutes. - SK

That's a lot of work -- sheer laziness was part of the reason that I was telling Mike to just go look in this forum for the last decade's worth of posts.

Please publish when you're done!  It sounds like what you're contemplating would make a good article for pinning or sending off to some magazine.  (If not a book).

If I were to read such an article, the things that I would look for would be the bullet points from my post on Mike's other thread, perhaps plus discussions of the effects (or perceived effects) of aspect ratio changes, dihedral, anhedral and high wing placements (for semi-scale projects), wing tip shapes, Rabe rudders, etc.

[Mike Griffin]

Serge I know you have more pressing issues than tutoring me and I certainly understand that.  I appreciate everything you have sent me in the past and will be sending along with all the information everyone on this thread has taken to time to help me with.  I just have an incurable thirst and curiosity for knowledge on certain aspects of this hobby and the input from everyone has been incredible and so much appreciated.  

I am not an engineer, physicist or mathematician and wrapping my mind around some of these things is hard to grasp and I guess I was hoping that over the years some sort of pattern had emerged for the right numbers and someone had written them down somewhere....In any case every bit of information has been greatly appreciated...

Mike

[Howard Rush]

based on quite a few years as a pretty good teacher of these skills.

You taught aeronautical engineering?

[Eric Viglione]

Mike - There are lots of rules of thumb some people use, aspect ratio's between 5-6 to 1, 25-28% tails, airfoils, moments, the lot. I'm no designer, but it sounds like Serge may have put together something like those rules for you with the math to back them up.

The trick is putting them into something that's pleasing to the eye, easy to build, power, and structurally sound. When I say structurally sound, I mean like take a typical stab, copy the area and ratio, but make it bowtie shaped. You now have a stab that will likely fold like a cheap tent.

Now, you could take measures to strengthen it, if you felt there was an advantage to that shape stab, but you will probably be adding tail weight to do it.
There is a lot of trade off in design I think.

Look at some v-tail stabs, a lot of extra work, but can be made to work well. But, there are also some trim issues and tradeoffs in flight character. I saw Tom Dixon fly his Adamisson V tailed  plane at our club contest (Sweet Pea I think?), and I was impressed that something that different looking could fly so well... Talked to Tom and he said it took a lot of work to trim properly for equal turn, but once he figured it out, it was fine.

Bob Hunt has had a canard on the back burner for years that he says would fly a competitive pattern, but he didn't sound too keen on the esthetics passing muster or something keeps him from building another one. I forget but it was his column photo for a long time. I think it was called Occam's Razor...

Lots of planes will fly, but since no one is paying us to do this, we tend to build what we like best. How many of us are guilty of taking the "new plane" that’s unproven and not really trimmed out yet to a contest just because we are excited about the new plane or design or we just think it's cool and we want to show it off? We might even claim to realize what a mistake it was, then turn around and do it again and again, year after year. Heh heh. (if someone thinks I am talking about them, I probably am, AHahahahahahah! ...myself included)  

EricV

[Mike Griffin]

Mike-

I fell down on the job. I've been quite busy with other things and have been off the forums for some time. I really did start with a quite lavish intro for you that was difficult to compose because of just what the guys here have been saying. Design does depend a LOT on what others have discovered by experience and evolution. That having been said though, it is indeed possible, with certain things that have been learned, to design a plane from scratch that will fly well at the intended goal - better than just throwing the dice, and as well as just copying.

Your  domino effect is not far from the mark, and I did indicate to you a sort of flow-chart outline that works. However, there are branches in the road. You can start with any parameter that you are set on achieving - like span, if you like - but power plant or wing area are more common (these all concern weight/wing loading and span loading, which lead to other choices, each of which have defined purposes). I mean, you may want something that fits your car, something for a favored engine, something for sport flying, something to deal with gusts, something for top competition, something to suit a budget, etc., etc. But the design parameters are all interrelated.

I will send you what I have done so far, even though I think that it is more complex an intro than the actual design sequence and techniques I'll introduce. I don't want it to scare you off, because my intention has been to actually create something that you can follow, right down to the math techniques, when necessary. Yes, there are a set of well-used, standard "formulas" (relatiobnships), but they can be handled. The last things that I'd gotten to in my little "exposition" were unfinished and not placed in their explanatory context. You'll see.

What this boils down to is that, unlike some other pretty excellent minds and modelers here, I think I can actually answer this question adequately and have this confidence based on quite a few years as a pretty good teacher of these skills. I'm sorry to have put you on the back burner so long and understand your frustration! Look for my e-mail in the next few minutes. - SK

Serge I got your e mail and thanks so much for taking the hours you must have spent doing that.  I will take me quite a while to digest the information in that e mail...
That is great information....

Mike

[Howard Rush]

I tend to believe those who I see scoring high in the contest reports...

But you have to consider who is compiling those contest reports.

[peabody]

I wish that Bob Hunt would build a full size version of the canard that he and Dean prototyped in 1/2A....
It would be way cool with electric......
Have fun!

[Howard Rush]

Electric would make it easy.  Too bad we can't convert Bob to electric.  You know how these old guys are set in their ways. 

[Serge_Krauss]

You taught aeronautical engineering?

Obviously not, as you know from my posts.

[Douglas Ames]

Mike-
I would start with the airfoil and wing planform first (aspect ratio), then tail moment/ stab area second. Nose/ engine moment is for balance after you've determined the overall form. Wingtips, fuse cross-section & form and gear arrangement are secondary design characteristics that all factor into the overall design.
One design trait does affect another. Adding tri-gear or an upright engine for ex., would have an effect on verticle CG. ...but, if it's part of your design, then raise or lower the wing to compensate.

[Doug Moon]

Mike-

I fell down on the job. I've been quite busy with other things and have been off the forums for some time. I really did start with a quite lavish intro for you that was difficult to compose because of just what the guys here have been saying. Design does depend a LOT on what others have discovered by experience and evolution. That having been said though, it is indeed possible, with certain things that have been learned, to design a plane from scratch that will fly well at the intended goal - better than just throwing the dice, and as well as just copying.

Your  domino effect is not far from the mark, and I did indicate to you a sort of flow-chart outline that works. However, there are branches in the road. You can start with any parameter that you are set on achieving - like span, if you like - but power plant or wing area are more common (these all concern weight/wing loading and span loading, which lead to other choices, each of which have defined purposes). I mean, you may want something that fits your car, something for a favored engine, something for sport flying, something to deal with gusts, something for top competition, something to suit a budget, etc., etc. But the design parameters are all interrelated.

I will send you what I have done so far, even though I think that it is more complex an intro than the actual design sequence and techniques I'll introduce. I don't want it to scare you off, because my intention has been to actually create something that you can follow, right down to the math techniques, when necessary. Yes, there are a set of well-used, standard "formulas" (relatiobnships), but they can be handled. The last things that I'd gotten to in my little "exposition" were unfinished and not placed in their explanatory context. You'll see.

What this boils down to is that, unlike some other pretty excellent minds and modelers here, I think I can actually answer this question adequately and have this confidence based on quite a few years as a pretty good teacher of these skills. I'm sorry to have put you on the back burner so long and understand your frustration! Look for my e-mail in the next few minutes. - SK

UH.......  You gotta let us see this stuff too, PLEASE!!

[Doug Moon]

Hello Mike,

I read both this thread and your other thread again.

I am not sure what you are asking. 

Are you wanting to design your own plane? 

Or are you just trying to figure out how the current models came to be?

Or both?

[Tim Wescott]

UH.......  You gotta let us see this stuff too, PLEASE!!

Yes, please.

[Mike Griffin]

Hi Doug

I guess both.  The reason I asked was to find out if that over the years and as stunt models evolved and got better and better, if anyone had ever written down the things that were used to get to the point where we are to day.  In other words do the great stunt ships share certain dynamics in common?  Do the best of them have high aspect ratios or low aspect ratio?  Do they share about the same span and area or AMC?  

What are the parameters you need to stay within to design and build a stunt ship that performs well.  This is fiction but what I imagine would be someone taking 100 different designs and analyzing them breaking down the numbers to see if they all shared certain things in common and then write that down as a guide for designing future models.  Does that make sense?

The answer to the first part of your question is yes...at some point I would like to design a stunt ship...mostly just for me and for the fun of it and I was looking for the above stated guidelines to follow in order to do it.  

Mike

[Tim Wescott]

I guess both.  The reason I asked was to find out if that over the years and as stunt models evolved and got better and better, if anyone had ever written down the things that were used to get to the point where we are to day.  In other words do the great stunt ships share certain dynamics in common?  Do the best of them have high aspect ratios or low aspect ratio?  Do they share about the same span and area or AMC?  

What are the parameters you need to stay within to design and build a stunt ship that performs well.  This is fiction but what I imagine would be someone taking 100 different designs and analyzing them breaking down the numbers to see if they all shared certain things in common and then write that down as a guide for designing future models.  Does that make sense?

The answer to the first part of your question is yes...at some point I would like to design a stunt ship...mostly just for me and for the fun of it and I was looking for the above stated guidelines to follow in order to do it.  

Do you get any modeling magazines?  Every stunter build article I've read has at least some justification from the author on why they did what they did.  Some -- notably Hunt's "Genesis", Werwage's "Junar", Walker's "Impact", and Ted Fancher's articles have gone into quite a bit of detail on the lineup of planes that led up to the one written about, often with comments on what worked and what didn't.  In addition, the control line stunt columns sometimes visit design, and from time to time there's a feature article on how to design for control line stunt.

And, as I've pointed out several times in these two threads already it's been discussed right here in the design forum over and over again.  So I'm a bit confused why, when you've been told that it's all right here you haven't disappeared for a few days, then come back with questions about specific posts.

A book would be nice (Oh Mr. Krauss...), but if you kept your Flying Models magazines you can read through them, there's years worth of stunt columns available on the Model Aviation site (assuming you're an AMA member), there's Stunt News and Control Line World, and again, there's this site right here with a trove of information in the design forum just waiting to be read.

[Mike Griffin]

Hi Tim

The reason I have not disappeared for a few days is that people keep asking me questions and I try to answer them.  ie Doug Moon.  I have all the information that I need for now but when someone asks me a question I try to answer it.   I have no more questions about this. 

Mike

[Randy Cuberly]

Mike-


What this boils down to is that, unlike some other pretty excellent minds and modelers here, I think I can actually answer this question adequately and have this confidence based on quite a few years as a pretty good teacher of these skills. I'm sorry to have put you on the back burner so long and understand your frustration! Look for my e-mail in the next few minutes. - SK

Serge,
I would dearly love to see this information also.

Please!

Thanks,
Randy Cuberly

[Trostle]

I have no more questions about this.  

Mike

OK, so you have no more questions on this.  But the door has been opened for some additional comments, and I have several.  As has already been suggested, there are countless articles on why individual designers did what they did.  Several years ago, Fred Carnes did an extensive series of articles in Stunt News that gave the history of the Detroit stunters and he took extensive measurements from those models, looking for some perhaps "magic" formula that group used for those successful airplanes which was a carefully guarded secret along with the I-Beam construction techniques from that era.  The editors of Aeromodeller magazine published a book with the title Control Line Manual, originally published in 1961.  In that book, a chapter was devoted to Aerobatics which chronicled the evolution of the CL Stunt model.  The article paid tribute to the pioneering work of Bob Palmer who was essentially the first to go to comparatively large, lightly loaded, moderate powered stunt models with flaps.  The book showed the evolution of the many Palmer designs through the Thunderbird and also recognized George Aldrich's Nobler.  It is these two designs that essentially established the framework for continuing evolution of our CL Stunt models.  (What that article does not explain, unfortunately, is the relationship between Palmer and Aldrich and the communication from Palmer to Aldrich as Aldrich was laying out the Nobler.)  That chapter also outlines some of the further developments at that time following the appearance of the Thunderbird and Nobler.  Anyway, that Aeromodeller book is still interesting reading and that one chapter was reprinted, with permission, in Stunt News several years ago.

Now for two more interesting items.

1.  In the January issue of the British Model Aircraft magazine (a magazine similar to the format of the Aeromodeller magazine), a table was printed that listed 16 designs (all from the U.S.) for .35 stunt ships.  This table gave fairly extensive dimensions for these models and then had a line for the "Trend".  Interesting for the time and now in hindsight, the trend showed what would now be considered a bit large for a "typical" 35 of 620 sq. in.and relatively small tails/elevators and flaps compared to our more " modern designs.  (For these who might be interested, I took those numbers and used them in a series of several designs, starting with an elliptical wing, but evolved to a straight tapered wing with a sort of semiscale appearance of a Focke Wulf which won the Walker cup in 1970.)  I will try to post that table here, but have an idea it will not show up well.  If anyone is interested in a copy, let me know.

2.  Now, fast forward to August, 1973, in the Round & Round Column written by John Blum (I think), where he compiled detailed dimensions for 24 stunt designs from that era, one unpublished.  His table broke those dimensions down so that non-dimensional comparisons could be made.  Makes for interesting study for those who might want to delve into this.  Again, I will try to scan this, but have an idea that it will not come out well.  For those who are interested, I will gladly send a copy.

So, what does all of this mean?  I think it has already been explained that our "modern" stunt ships are the result of an evolutionary process that was firmly launched in the 50's with the advent of the Smoothie/Pow Wow/Thunderbird and Nobler.  Power trains have vastly improved.  Construction techniques have improved.  New materials have appeared.  Design refinements have evolved.  Knowledge in trimming has been gained.  And there is still room for improvement, though like has been experienced over the past 50 years, I really doubt there will be any quantum leap forward with our toy airplane technology and ability to fly the perfect stunt pattern.


Keith

[Trostle]

And here is the MAN table from 1973

[Tim Wescott]

(For these who might be interested, I took those numbers and used them in a series of several designs, starting with an elliptical wing, but evolved to a straight tapered wing with a sort of semiscale appearance of a Focke Wulf which won the Walker cup in 1070.) 

Wow.  Keith.  I knew you'd been doing stunt for a long time, but this is just amazing.

[Mark Scarborough]

And here is the MAN table from 1973

Keith, I would enjoy a copy of these if you please? thanks

[Trostle]

Wow.  Keith.  I knew you'd been doing stunt for a long time, but this is just amazing.

Oops.  Missed the key stroke by one position.

Thanks for that.

[Dennis Leonhardi]

Mike, me thinks I understand what you're asking, having raised the question a time or two in different words ...

George Aldrich did an article or two way back when on "How to Design a Stunt Model".  I just tossed my copy (after all these years) a couple of days ago.  But I always felt George missed the boat by providing specific measurements (in inches) for a Nobler-sized airplane ... How does that help me design a .15-powered ship?

So I developed my own numbers, percentages of this and that.  I can't remember ever designing an airplane when I didn't start with "the numbers", and we're talking 50+ years.

It's worked pretty well for me over the years for semi-scale profiles, slow combat and sport airplanes.  Never a serious stunt design.  I will say my last serious attempt - a profile Ki-61 "Tony" - was my best: turned beautifully, yet it was rock steady in inverted level flight in a moderate wind.  Right off the board.  So it worked for me.

So here's what I'd like to see:

(1) What "numbers" do you use to design an airplane for any size powerplant?  Do you change percentages as you change size?  (Consider Aldrich's own Flite Streak series: the nose moment arm, as a percentage of wingspan, for example, differs dramatically if I remember correctly.)

(2) Do you "adjust" the numbers to suit your personal preference?

Many years ago I was having a lot of success flying combat in the Midwest with small, fast wings set up in such a way it would have been virtually impossible to stall them (if the engine was running, grin).  So many people asked for plans that an engineer friend drew a set up; Mike Stott (designer of the Sig Super Chipmunk and others) put together a foam wing kit.  And everyone who flew them complained that they were too nose-heavy and wouldn't turn tight.  Duh?!?

What works for me might be poison for you.

Dennis,
eager to see the numbers ...
 

[Tim Wescott]

Oops.  Missed the key stroke by one position.

Thanks for that.

Any time, Keith.  When pointless, compulsive proof-reading is needed, I'm here.

[Howard Rush]

OK, so you have no more questions on this.  But the door has been opened for some additional comments, and I have several.  As has already been suggested, there are countless articles on why individual designers did what they did.  Several years ago, Fred Carnes did an extensive series of articles in Stunt News that gave the history of the Detroit stunters and he took extensive measurements from those models, looking for some perhaps "magic" formula that group used for those successful airplanes which was a carefully guarded secret along with the I-Beam construction techniques from that era.  The editors of Aeromodeller magazine published a book with the title Control Line Manual, originally published in 1961.  In that book, a chapter was devoted to Aerobatics which chronicled the evolution of the CL Stunt model.  The article paid tribute to the pioneering work of Bob Palmer who was essentially the first to go to comparatively large, lightly loaded, moderate powered stunt models with flaps.  The book showed the evolution of the many Palmer designs through the Thunderbird and also recognized George Aldrich's Nobler.  It is these two designs that essentially established the framework for continuing evolution of our CL Stunt models.  (What that article does not explain, unfortunately, is the relationship between Palmer and Aldrich and the communication from Palmer to Aldrich as Aldrich was laying out the Nobler.)  That chapter also outlines some of the further developments at that time following the appearance of the Thunderbird and Nobler.  Anyway, that Aeromodeller book is still interesting reading and that one chapter was reprinted, with permission, in Stunt News several years ago.

Now for two more interesting items.

1.  In the January issue of the British Model Aircraft magazine (a magazine similar to the format of the Aeromodeller magazine), a table was printed that listed 16 designs (all from the U.S.) for .35 stunt ships.  This table gave fairly extensive dimensions for these models and then had a line for the "Trend".  Interesting for the time and now in hindsight, the trend showed what would now be considered a bit large for a "typical" 35 of 620 sq. in.and relatively small tails/elevators and flaps compared to our more " modern designs.  (For these who might be interested, I took those numbers and used them in a series of several designs, starting with an elliptical wing, but evolved to a straight tapered wing with a sort of semiscale appearance of a Focke Wulf which won the Walker cup in 1970.)  I will try to post that table here, but have an idea it will not show up well.  If anyone is interested in a copy, let me know.

2.  Now, fast forward to August, 1973, in the Round & Round Column written by John Blum (I think), where he compiled detailed dimensions for 24 stunt designs from that era, one unpublished.  His table broke those dimensions down so that non-dimensional comparisons could be made.  Makes for interesting study for those who might want to delve into this.  Again, I will try to scan this, but have an idea that it will not come out well.  For those who are interested, I will gladly send a copy.

So, what does all of this mean?  I think it has already been explained that our "modern" stunt ships are the result of an evolutionary process that was firmly launched in the 50's with the advent of the Smoothie/Pow Wow/Thunderbird and Nobler.  Power trains have vastly improved.  Construction techniques have improved.  New materials have appeared.  Design refinements have evolved.  Knowledge in trimming has been gained.  And there is still room for improvement, though like has been experienced over the past 50 years, I really doubt there will be any quantum leap forward with our toy airplane technology and ability to fly the perfect stunt pattern.


Keith

Then there was Bill Netzeband's huge compilation of stunt plane parameters, posted here (or maybe SSW) the last time Mike asked about this stuff.   

[Trostle]

Then there was Bill Netzeband's huge compilation of stunt plane parameters, posted here (or maybe SSW) the last time Mike asked about this stuff.   

Howard,

You are right.  I did not intentionally overlook Netzeband and his work.  I have a binder filled with his columns, articles and construction articles.  He certainly has contributed to the material we can use when thinking about stunt design.

Keith

[Mike Griffin]

Tim and Howard....who is ignoring you?? 

Mike

[Serge_Krauss]

Hey, guys -

'just back for a "short" visit during a WAY too-busy time. While I've written and illustrated several pages of my "simplified" recipe for stunt design, it's still not completely ordered nor organized even now. Things will move, be filled out, shrunk, re-worded, and otherwise changed as they develop. One of us (Tim?) got the idea pretty close, but I am also trying to develop background, like understanding forces and their locations, moments, Newton's Laws, basic operations, etc. to show enough context for overall understanding. This is part of my own outline, stating the sequence in brief, before explaining the steps. The arrows show just the sequence, rather than causes, although you generally need to know what preceeds to do what follows.

"II. Primary Forces, their locations and Moments: Lift, Thrust, Drag, Weight, Centripetal Force, Pitching Moments

"III. Overview of Design Sequence: Engine/weight => Decision: flapped or un-flapped? => Wing Size/Area => Wing Aspect Ratio => Wing Shape/Sweep/Taper => Wing Dimensions => Wing MAC => Wing a.c. => c.g. Position (or later using N.P of plane) => Choose TVC Value => Tail moment arm vs. Horiz. Tail Area (Choose appropriate Combination limited by TVC choice)  => Horizontal Tail Aspect Ratio => Horizontal Tail Shape => Stab/Elevator Dimensions => Vertical Placement of Components => Other moments and Forces => Review => Further Trade Offs."

My goal is to show how one can do this, with the caveat that even with this, I can't do it all. For instance, mine is the old time design approach that if the plane is statically stable and maneuverable, then its dynamic stability will be OK, with just some scientific, common-sense care. I suspect that one of us here would not be satisfied, unless I re-acquaint myself with this area, and addressed it mathematically, along with roll/yaw couples. I don't see that happening at this point, at least not for this kind of thing. Well, that's the place I am now; 'haven't been at it for a while..

If you really want to know how muddled my stuff is during creation or editing, you can e-mail me ('skrauss at ameritech dot net'). Lots of "stuff" needs re-ordering, completion, and re-editing as it stands. I think the actual sequence and example will be briefer and easier to present than the background. I just gave Mike what I had done so that he would know I had not forgotten him.

SK