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Author Topic: Ted and Design, a request from Da Dirt  (Read 1964 times)

Offline dirty dan

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Ted and Design, a request from Da Dirt
« on: February 11, 2006, 01:13:04 PM »
Ted,

Assuming the listing of Terrible Ted as being the moderator for this forum is correct, I would like to suggest that you take some time to illustrate the concept you and Bill Fitzgerald came up with as it relates to the "numbers" of various designs.

Yes, I have my own copy of a past article you wrote on the design and construction of the Imitation, this courtesy of Derek Moran.

I still see this as a viable topic for this forum, especially with what I detect as some interest in scaling certain designs up or down, as I have done with the Impact.

Another application is in fiddling with something quite basic, the SIG Skyray 35 for example, something else in which I have interest, to date merely having failed to ruin Mikey's original design...

My best,

Dan
 

Dan Rutherford


Offline Ted Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #1 on: February 12, 2006, 06:24:28 PM »
Hi Dan,

I expect you're talking about the numbers sheet that was (I believe) a part of the Imitation and Excitation articles.  I agree it would be a good starting place for a discussion and might also play right into Jim Pollocks thread on a "team" design effort. 

Assuming you're more of a computer afficianado than me, maybe you could scan it into a post.  I haven't a clue how to do that sort of thing.  Maybe it could be scanned into a word document and then edited to remove the numbers and we could juxtapose the filled in Imitation one and a blank one.

Ted

Offline dirty dan

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Re: Ted and Design, a request from Da Dirt
« Reply #2 on: February 13, 2006, 02:12:45 PM »
Ted,

I don't have the tools to scan anything and then post it here.

Yes, the reference article is the two-parter you wrote on the Imitation.

I was sorta thinking you could just recite this stuff from memory...

Dan
Dan Rutherford

Offline Ted Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #3 on: February 14, 2006, 04:01:30 PM »
Ted,

I don't have the tools to scan anything and then post it here.

Yes, the reference article is the two-parter you wrote on the Imitation.

I was sorta thinking you could just recite this stuff from memory...

Dan


Spoken just like a reforming smoker.  Nothing but the habit.

Maybe someone can give me a briefing on the steps required.  I've got a scanner which does a decent job with character recognition and I think I can find the articles in question.  Getting them on the forum

Was there a table in the Excitation article?  Sheesh, old timers does nasty things to a guy.

Ted

Offline Warren Wagner

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Re: Ted and Design, a request from Da Dirt
« Reply #4 on: February 14, 2006, 07:06:06 PM »
Hi gang,

Here is the table with the parameters for the Imitation design.   I was unable to use OCR and create an editable file to create a blank form, but I'll keep trying.  Sorry about the quality of the scan, but jpeg compression to get under the 50kb limit lowered the legibility.

If someone has good OCR software, that would be great to create a blank form, otherwise I could just type one up.

Cheers.

Warren Wagner

« Last Edit: September 24, 2006, 09:27:01 PM by Warren Wagner »
Warren Wagner
AMA 1385

Offline Ron Hofacker

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Re: Ted and Design, a request from Da Dirt
« Reply #5 on: February 15, 2006, 09:43:13 AM »
http://www.control-line.org/Portals/57ad7180-c5e7-49f5-b282-c6475cdb7ee7/Imitation%201.pdf

Here is a link to the article on the PAMPA web site...


Ted, et.al.

There are several articles like this one, the articles by Bill Netzband, and a few others that address some of the basic physics and aerodynamics of C/L. I think it would be very worthwhile to republish these articles in Stunt News. Intrest in PA seems to be renewing and many of us newbees/retreads do not have easy access (or even know they exist...) to many of these articles.


Offline ash

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Re: Ted and Design, a request from Da Dirt
« Reply #6 on: February 16, 2006, 01:47:13 AM »
Just read that article, its excellent stuff. It has been very helpful in confirming some of my decisions about the wind verison of my next model.

I think it would be a very useful resource to distribute a spreadsheet template of that table so that people can collate the numbers for a wide variety of great aerobatics craft. Imagine the long glorious hours of comparitive analysis we could indulge in through the chilly winter nights! ;D
Adrian Hamilton - Auckland, NZ.

Offline dirty dan

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Re: Ted and Design, a request from Da Dirt
« Reply #7 on: February 17, 2006, 01:39:31 PM »
Spoken just like a reforming smoker.  Nothing but the habit.

Maybe someone can give me a briefing on the steps required.  I've got a scanner which does a decent job with character recognition and I think I can find the articles in question.  Getting them on the forum

Was there a table in the Excitation article?  Sheesh, old timers does nasty things to a guy.

Ted


Ted,

While I am sure that I read the article on the Excitation, I am equally sure that it was one time through and then to a combat plane in the works...

I thought there was a lot of Kewl Stuff in the Imitation article, however.

There has not been much done with Pukey Profiles since your Doctor/Medic article, and for reasons which are hard to explain, profiles have been an intriguing device for me lately.

How's about an analysis of the SIG Skyray 35? They seem to be catching on, and while the Big Deal remains the power plant, the 20FP w/BB T-U being to date the ideal, I am interested in improvements to the basic design. Or at least a discussion as to potential improvements.

Dan
Dan Rutherford

Offline Ted Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #8 on: February 22, 2006, 08:39:00 PM »


Dan,

You've hit the nail on the head.  The engine is the big deal.  Look what modern power trains have enabled Ringmasters to do in classic in the hands of a good driver.  You can do amazingly good tricks with a straight and reasonably light Ring with a going Veco .19 or unmentionable .20 in it ... until the engine quits and it turns back into a pumpkin.

Trouble is, if we give the engine its due, the whole idea of a famous stunt plane designer loses a lot of its panache.  Where would I go to get my strokes :-[ :-[
Who will buy be fancy dinners in hopes of picking my brain?

Don't remember which article it was but Billy W. pretty much hit the nail on the head when he said the engine is about 80% of a good stunt ship.  A bit extreme (don't want any 100 square inch canard pushers with a .90 in them) but it isn't far wrong when combined with any remotely reasonably designed and excellently trimmed stunt design.

Ted

Offline dirty dan

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Re: Ted and Design, a request from Da Dirt
« Reply #9 on: February 23, 2006, 12:11:33 PM »
Ted,

I have completely reversed field on the more salient considerations as to choices in engines and models.

When I started flying CL Stunt I chose the Smoothie because Don McClave's looked kewl and I kinda wanted to fly with a Fox 35 anyway.

This pattern followed for quite a few models: Pick a design first and then figure out how to power it.

Wrong approach, even if widely used.

I now pick the engine first. And then look for a suitable model.

Dan
Dan Rutherford

Offline Ted Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #10 on: March 02, 2006, 06:01:49 PM »


You mean you don't memorize my stuff?  I'm shocked.  Sometimes I wonder why I even bother.

FWIW, that table isn't a bad place to start.  I developed it for two reasons.  First to allow myself to tabulate measurements off a bunch of plans that Fitzgerald the elder and myself had laying around and second and most important was because I felt that if you're going to "design" a plane to do stunts the aerodynamic elements should be the first priority rather than the ultimate result of drawing something that appeals to the "designer" aesthetically.

It is thus more or less a fill in format on which the designer can play with numbers to give him an idea of what is necessary to achieve the outcome he desires.

It is based on the absolute most basic of aerodynamic principles such as area, aspect ratio, wing loading and relationships of proposed centers of Gravity, Lift, Drag, pitching moments etc.

THIS IS IN CAPS SO NOBODY CAN MISS IT.  I DON'T PRETEND TO BE AN AERODYNAMIC ENGINEER OR TRAINED IN THE ARTS OF AERODYNAMICS.  I AM, ON THE OTHER HAND, A LIFELONG PILOT TRAINED IN THE ARTS OF FLIGHT AND HAVE A GOOD GRASP ON HOW THINGS EFFECT ONE ANOTHER IN A BASIC FLYING MACHINE. THE TABLE IS INTENDED TO ALLOW SOMEONE WITH THOSE FUNDAMENTAL SKILLS TO ANALYZE THE RELATIONSHIPS AND TO ADJUST THEM TO ACHIEVE A PREDICTABLY FLYABLE RESULT.  DON'T WANT ANYONE TO THINK MY EXPERTISE IS ANY GREATER THAN WHAT'S JUST BEEN STATED.

To use a resource of this type one must first decide what it is he wan'ts to achieve in a new design.  He must then be reasonably aware of the numbers that would show up on the form for a known quantity...again, probably the Nobler would be as good a basic reference as any.  If you have the numbers for a Nobler (or, which might be easier, the numbers for the Imitation or Excitation as already filled out in the construction articles) and; if you are familiar with the performance and flight characteristics of that reference airplane (Nobler or Imitation), you can then start to play with the numbers with some reasonable expectation of achieving the desired result.

An example might be a question I was asked at the field the other day.  The flyer wanted to know what he could do to reduce the control loads on a modern stunt behemoth while still being able to produce a competitive corner.  Other than the obvious mechanical solution (a bigger wrench to deflect the flaps and elevators [bigger bellcrank leadout arms]) we discussed pitching moments caused by flaps and the effects on aircraft response. 

You could predict, using numbers plugged into the template, that reducing the area of the flaps by reducing chord or span of the surface would reduce the load on the control system.  You could also do it by getting the CG and center of lift of the wing closer together which would reduce the pitching moment, etc.

Without going into great detail (and I encourage any of you interested in more detail to pick up copies of any of my longer published articles from PAMPA PRODUCTS), the fundamental stuff you can play with in the form is the teeter totter stuff that makes our stunters feel the way they do in the air.  Where the CG and centers of lift etc are located and the effects that changing those numbers will have on the teeter totter.

Too much stuff here.  the bottom line is the form can be a helpful tool to help predict the way a design will perform under a certain set of trim conditions.

What must be remembered is that our ability to trim any aircraft ... Nobler to Impact ... is really much more important when push comes to shove at the contest site.

If anyone can read the form well enough to ask specific questions about it, fire away.

Ted

Online James Lee

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Re: Ted and Design, a request from Da Dirt
« Reply #11 on: September 14, 2006, 03:43:01 PM »
Ted
Just a comment...   The 'numbers' that you used for the Imi have proven for me to be a real boon.  As you point out they try to quantify the parameters of a particular design...   I've used the Imi number for several designs and have been very pleased with the results.
My first try, the 'Mutation' ( and that was NOT meant in any derogatory fashion) (Imitation with a fuselage) was built just before the 1980 Nats, actually finished mounting the motor in the motel on the way to the Nats that year.  I just sent a pair of ST 46's to Tom Lay for 'fixing' and plan to get the old bird back in the air!  Have to fix the John Poynter foam wing where it is starting to delaminate at the OB trailing edge...  Really looking foreward to that plane with a really nice motor.
Thanks
Jim

Offline Ted Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #12 on: September 17, 2006, 07:02:58 PM »
[[Ted
Just a comment...   The 'numbers' that you used for the Imi have proven for me to be a real boon.  As you point out they try to quantify the parameters of a particular design...   I've used the Imi number for several designs and have been very pleased with the results.
My first try, the 'Mutation' ( and that was NOT meant in any derogatory fashion) (Imitation with a fuselage) was built just before the 1980 Nats, actually finished mounting the motor in the motel on the way to the Nats that year.  I just sent a pair of ST 46's to Tom Lay for 'fixing' and plan to get the old bird back in the air!  Have to fix the John Poynter foam wing where it is starting to delaminate at the OB trailing edge...  Really looking foreward to that plane with a really nice motor.
Thanks
Jim ]]

Hi Jim,

Glad you like you Mutation.  During the era you built that ship quite a few very similar ships were flown here in northern California with extremely competitive results (built up fuses on the basic Imitation wing and tail).  David Fitz, for instance, built about three such ships after getting out of active duty to get himself into the (at that time) modern era.  He did extremely well with them and still has a couple hanging on the wall of his garage.

That approach is still a very good way to go.  I liked my Imitation probably more than any other original design of my own.  It was very stable, turned extremely well and was very insensitive to trim ... flying very well with a bunch of different engines.

If I can get my enthusiasm drummed up a bit I have a mental plan for a twin Imitation with two OS .30 Surpass four strokes in mind.  It would be a kick and I think the airplane would have no problem carrying the weight.

Let us hear how it works out when you get it back in the air.

Ted

Online James Lee

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Re: Ted and Design, a request from Da Dirt
« Reply #13 on: September 17, 2006, 08:10:08 PM »
Ted
I'll let you know when the Mutation gets back in the air!!   Still gotta repair the wing   :P :(   
And to add to a previous comment about percentages to change a design from one wing area to a different one...   
For instance, a slightly smaller Imitation for P-40...    Maybe 580 sq ..   Divide the area of the one you want by the area of the one you got   so, 580 divided by 630= 0.9206 etc, then take the square root of .92 etc and that is .95949 etc...  or app 96 %.  alter all the dimensions of the Imitation with that percentage and you will have the 580 sq in Imitation.  Just need to know the wing area of the origianl design and the area of the latest greatest that you want to build slightly or a lot bigger or smaller.
Later
Jim    

Offline Ted Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #14 on: September 19, 2006, 11:29:12 PM »
excellent point, Jim.  And a lot easier than my tripping around the edges of it.

Still making those fancy syringes?  Got a couple of guys antsy for them at the flying field.

Give lovely Lila a hug for us, will you?

Ted

Online James Lee

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Re: Ted and Design, a request from Da Dirt
« Reply #15 on: September 20, 2006, 03:09:59 PM »
Ted
The syringes are back in stock!!  I was really upset that I ran out at the Nats!!   :-[   Email for details, I'll be happy to fix them up.    ;D  Check my add in the current Stunt News...
Jim
Add PS Lila says Hi, just got back from a visit to NJ, 'Jersey Boys' on Broadway, and lunch with Todd at Newark airport!
« Last Edit: September 20, 2006, 05:19:44 PM by James Lee »

Offline Terry Fancher

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Re: Ted and Design, a request from Da Dirt
« Reply #16 on: September 26, 2006, 03:57:41 PM »
Neat.  I'll tell Uncle Jimby and Phil to check them out.

Ted


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