Tube sizing for aircraft fuselages 3

[Crunk]

I'm trying to build a small biplane originally designed in the 20's and modified quite a bit since then. I was wondering if someone could point me to a book(s) that would explain how to do tube sizing and stress analysis on a tube steel fuselage.
I'm an A&P and a pilot and I've built several airplanes. The plans I recently received are a myriad of different modifications of the original. (Touted to be complete but woefully short.) I plan to re-draw the plans on AutoCad so I might have a workable set of plans. The designer died in 1980 so I want to recheck his plans to see which variations of them are really for the model I'm trying to build. The company selling the plans hasn't been much help, as there probably isn't that much interest in this single seat design. It seems that this information for this type of construction is becoming as dated as me and my plans.
Thank you for any assistance you might be able to provide.
Crunk

 

[Sparweb]

Sounds like a fascinating project. You would benefit greatly from talking to some EAA members. You may eventually come across an expert who's got the same airplane, or at least solved the same problem.

My first thought about restoring tubular frames is Alexancer Klemin's "Airplane Stress Analysis", from 1929, published by the Ronald Press Company. Instead of studying the most modern and advanced approaches to designing these structures, you would be reading the "state of the art" of the epoch, which could help you produce a more authentic result. The book is structured much like a textbook, with realistic examples, so it would be easy enough to work from.

Check your results against the FAA's current publications, such as AC 43.13-1B, or you will have trouble obtaining a CofA, later on.

A Google search on the title pulled up this:

http://www.wlbooks.com/cgi-bin/wlb455.cgi/3096.1.html

but I've never used this supplier, so, caveat emptor.


Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[Crunk]

Sparweb,
Thanks a bunch! I'll begin my search for the book immediately.
I did locate the son of a builder of this airplane. His Dad died about five years ago, but he still has the airframe (dis-assembled) and has invited me to take pictures.
The book you mentioned should 'fit my bill' prefectly as I'm trying to reproduce an airplane from the same era.
I'll let you know how the project progresses.
I also have two friends that are interested in building this same machine. I guess we'll build three at the same time!
Crunk

 

[sreid]

Here's a website that might interest you.

http://www.aircraft-spruce.com/

 

[Sparweb]

Crunk,

I'm definitely interested in how your project progresses, and don't hesitate to ask if you have any more questions. Also note that there are several other forums more suited to a "structures" question, and asking your question there will attract a wider audience. The aircraft engineering forum may also have some previous posts with helpful info.

Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[Crunk]

sreid,
Thanks for the tip. Fortunately Aircraft Spruce is located about six miles from my home which makes my project a lot easier to complete.
As far as I know the airplane I'm planning to build is the only cantilevered wing biplane ever designed. It's called a Knight Twister and was designed by Vernon Payne in 1928.
It has a dubious history due to it's 'hot' characteristics. After reviewing the plans I'm quite sure some of it's reputation stems from the difficulty involved in building the machine. The wings are double tapered and since they are cantilevered, must be constructed very carefully to achieve the proper flight characteristics. My plan is to put the plans into AutoCad so I can use a CNC router to cut out the wing ribs and support cradles to get the needed accuracy. Without this accuracy I'm sure some of it's reputation is probably valid! In my research to date I've talked with people who have stated the airplane is barely controllable and others who have said it's a real solid machine. The people who reported negatively were not the builders. I suspect the machines they flew were not constructed properly, as one of the people I talked to said his father built one and flew it for 500 hours. Sorry to be so windy.
crunk

 

[WKTaylor]

Crunk...

I assume You have talked with the company at the enclosed website... which still sells plans and parts for this aircraft?

http://www.steenaerolab.com/KnightTwister/

Regards, Wil Taylor

 

[Crunk]

wktaylor,
I bought my plans from them but they really don't support or offer parts for the aircraft. The plans are a conglomoration of revisions, many of which do not apply to the model I'm trying to build, thus the reverse engineering. Hale Wallace was a friend but due to circumstances I was never able to see his airplane before he died. It seems he had talked to some of the same people I've been running down for advice, so I think I'm slowly headed in the right direction. Any and all suggestions are certainly welcome.
crunk

 

[Crunk]

SparWeb
I just received my book "Airplane Stress Analysis" by Alexander Klemin. It's just what the doctor ordered! It will take me a while to work through it, but it seems to answer all the questions I had. (It's also like stepping back in time to see the "State of the Art" of the late 1920's.)
The folks at wlbooks.com are also top-notch and I would highly recommend them.
Thanks once again,
Crunk

 

[Sparweb]

Crunk,

Glad to see you found some good holiday reading. When you get to things like the force vector diagrams, you might want to take advantage of more modern technology, once you've got the hang of it on paper. AutoCAD would work well for this purpose.


Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout

 

[Crunk]

SparWeb,
Can you say, "I'm in over my head?" Actually for the arithmetically challenged, AutoCad does help immensely! It's a bit tedious but do-able.
Determining the loads involved seems to be the biggest problem so far, but a spread sheet helps to keep things a bit more manageable.
Me thinks the winter will find me glued to the computer, and after several months of hard work I hope to be attuned to 1920's technology! (Emphasis on I Hope!)
My thanks again for your book selection. I think this one book would allow anyone to design a 1920's aircraft from start to finish........as to present day technology....well, at least you guys won't have competition from me!
crunk

 

[Sparweb]

I think this one book would allow anyone to design a 1920's aircraft from start to finish........

Not true!

Look up the NACA Reports:

http://naca.larc.nasa.gov/

and:
ANC-18: Munitions Board Aircraft Committee, June 1951, Design of Wood Aircraft Structures
USA Naval Depot
5801 Tabor Avenue
Philadelphia, PA.,
U.S.A. 19120

(See if those guys also have ANC-19 and ANC-5, while you're at it. You might also get a copy of ANC-5 from the Smithsonian, but for some reason they don't have a copy of ANC-18.)


Steven Fahey, CET
"Simplicate, and add more lightness" - Bill Stout