Replica Sopwith Camel Construction Process

greatwarpilot · 26 December 2005, 09:03 PM

Baldeagle - Interesting to hear the plans you have for hiding modern instruments. We have a similar plan for the Camel where any instruments that originally weren't on the main panel will likely be hidden somewhere yet to be determined (boost gauge, radio. switches, etc).

It’s also interesting to hear your choice about the modern ASI largely for the purpose of checking out other pilots. It doesn't seem like one often hears about a WWI replica builder (with a rotary no less) that has that in mind.

baldeagle · 27 December 2005, 06:30 AM

Well, I've only ever owned 4 flying airplanes, and I've flown over 100 types, so there have been a lot of generous people over the years, and I'd like to do some paying back. Plus I have a lot of highly qualified friends that I'd like to share the rotary engine experience with. I've got a line on a possible 80 LeRhone, which if I can get I think someday I'll build a Nieuport 10 for, so that I can give dual in it. Just takes time and money.....

hank jarrett · 27 December 2005, 09:28 AM

Quote:

Originally Posted by jumpinjan

Hank,
How quickly could you do an analysis (and possibly optimize tubing size & wall thickness) of a custom steel tube fuselage if I could provide the data in a form that you specify? Do you have tools available to automate the analysis like NASTRAN? That's the last one that I used back in 1978.

I'm afraid I don't have any tools except my old texts and a copy of AutoCad 12 somewhere on an old machine. The last time I did a full analysis of a tube fuselage was before NASTRAN. When NASTRAN came out I was head of the structures section on the A-6 Intruder for the NADEP in Norfolk VA. I had young bucks fresh out of school to run the analysis and I just checked their work. That's why I would really like to see the analysis on the Sopwith. See if I can get the old neurons firing again. Now I spend my time working Systems Engineering and Safety Engineering for NASA. I never seem to get to play with structures any more, but would like to.

brisfitworks · 26 March 2006, 06:50 PM

Hello everyone following this thread.

Having only recently gotten into the fry at the Aerodrome (and with urgings from my museum members) it is time to put some answers to your questions, from the "horses mouth" (or any other end you wish to feel they come from ;-)

I am the guy that has been heading up our Camel replica project. My name is Bill Batter and I am also the current president of our museum.

Just a bit more history on how this project came about ...

(if your curious about what museum I am talking about, visit www.greatwarflyingmuseum.com)

The project started in the fall of 1999. The museum wanted to start a new airplane and major part of the reason was for improvements in member involvement and enthusiasm. There had been some years of debate as to what to build and how to build it but, in the end, airshows and their audiences won out: "is that Snoopy's plane" or "do you have Snoopy and the Red Baron". (it was as good a reason as any to get concensus at our museum).

The whole project was designed around trying to have as many members involved no matter their skill level. So a lot of people learned skills they never even heard of! We now have people that can form aluminum on lead shot bags who were thought so dangerous with a hammer as to not be allowed more than a broom to use!

Biggest challenge was that I was put in charge of the project and I wanted it as close to the original as possible but we had skill limitations and a big debate on how flimsy and unsafe wood fuselages are. So a major compromise had to be made to incorporate a steel tube fuselage.

I wanted to design a fuselage that would not compromise the design of the other sub-assemblies, so they could be made per original drawings (thus eliminate the effort and time to reinvent everything) and to keep external and cockpit visible appearances almost indistinguishable from the original.

Another exception from original design was made because of service life and because we had a steel baseframe: all the ply side panels and turtledecking was beefed up and made removable for serviceability and repair ease. Our planes last 10's of years instead of the 10's of days in WW1! If you've ever seen the promo photo Martin Baker put out of their MB-5 fighter with all its service panels removed, you'll understand my concept for serviceability.

The last exception, which I'll mention because someone out there knows this plane well enough to notice, is I designed a box spar to replace the spindled ones. Purely on a durability basis. This plane has to be a work horse and must see decades of reliable service and suffer the occasional OOPS! without requiring a major rebuild.

Both to get people working while I designed the steel fuse conversion and to make that design process easier to visualize, we built "the Mock-up" of the original framework as a jig to assemble onto and to form the ply side panels and turtle-decking. In the end stages the mock-up became our welding jig for the slab side of the steel frame.

This bought me the time I needed to design a fuselage. Not an easy task because, when you do the math, it is very difficult to come up with a steel tube fuse as light and stiff as spruce and wire!

You can see from the photos the different stages. What you don't get to see is that the wings are now done save trailing edges and root ribs and root spar boxes. All the control surfaces are done except for the tube outline. Undercarriage is ready for assembly and final fitting. Cabane struts are made. and so on.... We have piles of part and assemblies stuffed here and there.

Ok, so some answers to questions ....

STEEL FRAME CONVERSION
========================
The steel frame design was engineered internally and yes it is a Warren truss. I like Mr. Warren. I thought that no other choice could be made. Warren proposed his truss design because of its economy on material and ease of adaption to tapered members. (sounds like what one needs for the tail boom). Problem is, a Warren truss is easy to conceptuallize in 2D but in 3D you are always fighting with too many tubes in a cluster where the joints are and trying to get torsional stiffness the same in both directions. It gets messy. So the Warren truss is mostly 2D. The top and bottom of all the bays is wire braced. For lots of reasons but since we are talking about frame design because it eliminated tube cluster congestion and gave me lots more stiffness so that I could drop off some weight in the frame. It came out stiffer and lighter than a pure tube design.

EXTRA HP AND LOAD ON THE ORIGINAL BITS
====================================
The biggest confusion I keep running into is the difference between HP and torque. If you take a 1.5litre engine give it 60psi boost and run it at 12,000 rpm you can get 1000hp! But that only becomes 440 ft-lbs of torque. Whereas a Merlin, at that hp, will produce something like 10 time that torque. It is the torque that wrenches the frame and flips the aircraft on its back when you snap the throttle forward. So what about a 160hp Clerget? Well at 1200rpm it has to be twisting the airframe with something like 700 ft-lbs of torque! More than once and half again as much torque as that 1000hp race engine! Horsepower can be misleading when making comparisons with WW1 engines.

The answer is that our Russion AI-14 engine will not be loading the structure by anything drastically different than the original. The flight loads would only be much greater if we could convert that apparent extra hp into extra speed. That will be difficult to do, to a dangerous level, since the prop and the draggy aeroplane will limit much of that and the pilot is supposed to be in control of speed and throttle. (for reference the assumed specs for our AI-14 is 300hp @ 2950rpm on the crank and a 0.658:1 gearbox. We don't have the exact manual for this engine yet so I am working with a mix of AI-14 and M-14P info. Anybody out there got a AI-14 manual, even in Russian would be grand!

Handling will be very different just because we do not have the Camel's most distinctive flying quirk: gyroscopic precession! I can well imagine how precession was probably a significant cause of many take-off accidents for novice pilots - it is hard enough learning to fly a fighter with 15hrs of instruction without having the thing crank sharply in roll when you yank back on the stick too fast! Save that, I hope the flying character will be very similar to the original.

STRESS ANALYSIS
================
The most obvious evidence of stress analysis is the lost of most of my hair above my forehead ;-)

Hank, I'd love to give you a pet project! If the offer to check the work is still open I'd like to get some stuff past your eyes.

Alot of the design is based on comparisons. I was not willing to do an entire aerodynamic analysis of the aircraft to figure out the loads I should support so I used the original Sopwith design to infer the loads that the structure was capable of supporting and worked to match and exceed that. I have a bunch of stuff on original loadings and design standards and structures textbooks of the time to understand how they designed such spruce and wire frames. With that and a lot of assumptive and by-the-seat-of-your-pants stuff I developed the numbers and I know this will be one of the strongest and most rugged fuselages we have in our fleet.

As for the method of chunching numbers for the frame, it was all done by hand and with spreadsheets. I've had to write Fortran programs for crunching stress and stiffness matice calculations before but really felt that by the time I relearnt that and reinvented the program code I could have crunched it out by hand and had something easier to be peer reviewed. There isn't a whole lot of software out there that easily lends itself to a Sopwith Camel frame so learning curve for adapting modern tools once again pushed me back to pen and paper.

SOME COMMENTS TO EXPLAIN THE PHOTOS
====================================
In this thread you will see a number of photos of different stages of construction. Some would make you go HUH?

You'll see a photo in Greatwarpilot's 9 Dec.'05 posting where all the panels are being fitted to the "mock-up" frame which is suddenly missing its tail. What happened was, as soon as the steel, rear fuselage was welded up we cut off the wooden tail of the "mock-up" and started converting the wood frame into an set of upper and lower wooden panels which would simulate the original wooden frame for the fabric. The upper panel incorporated the formers and stringers of the rounded, fabric turtledeck. In this way, the fabric would be supported to hide the steel frame and make even the most discerning eye unsure if the frame was original wood or metal tube. This you can see hints of in Greatwarpilot's 11 & 22 Dec.'05 postings.

YET TO COME
=============
We are back onto the Camel in a much more concerted way now. We've pretty much given a total rebuild to every plane in the fleet over the last 6 years and now the Camel is the only major project demanding attention. In the weeks to come, we will be finalizing the installation of the hump, turtle decking and side panels onto the fuselage frame which means the welding is done and painting can begin on the frame and the interior details can start to be re-installed. That is when it will get more fun (there will be lots of guys climbing into the cockpit and playing pilot trying not to get caught muttering engine and machine gun noises! LOL!!)

We'll keep you posted. Hopefully, it is interesting for you and we would much appreciate any questions and advice and comment you might have.

Cheers!
Bill

RFC Pilot · 26 March 2006, 07:25 PM

Nice to see you here Bill.

greatwarpilot · 26 March 2006, 07:37 PM

Agreed. Glad you could join the fun and provide a more detailed overview of the project Bill.

brinesharks · 6 April 2006, 09:13 PM

Quote:

Originally Posted by brisfitworks

Hello everyone following this thread.
The whole project was designed around trying to have as many members involved no matter their skill level. So a lot of people learned skills they never even heard of! We now have people that can form aluminum on lead shot bags who were thought so dangerous with a hammer as to not be allowed more than a broom to use!

What a great inspiration for other groups/museums. The museum I am involved with (as an unskilled volunteer!) has started Spitfire project. A lot of people thought the museum would not have the support or funds to build one - the opposite has happened. It has invigorated the museum and it's amazing how much people will donate of their personal time and/or money for such a worthy (and iconic) project. Keep up the good work!

brisfitworks · 7 April 2006, 01:05 PM

Quote:

Originally Posted by brinesharks

What a great inspiration for other groups/museums. The museum I am involved with (as an unskilled volunteer!) has started Spitfire project. A lot of people thought the museum would not have the support or funds to build one - the opposite has happened. It has invigorated the museum and it's amazing how much people will donate of their personal time and/or money for such a worthy (and iconic) project. Keep up the good work!

Thanks for the compliments. It is much appreciated and one the few rewards to what one does in a museum.

Inspiring people really is the key to a volunteer based organization.

Even true for a place full of paid employees too, but you can't get something done by threatening to fire a volunteer nor offering them a raise, even doubling their "salary" doesn't much to motive a volunteer. We often joke at our museum, after a job is well done, that we'll double their pay! Usually, offering to buy them a pint is more successful and worth more ;-)

It is projects and objectives and goals to work towards that gets people going. The Camel is an example of both extremes: something that gets people inspired because of the grand results and deflates them because it takes a long time to acheive. The "rub"! how to keep them inspired over the long term. Tough challenge, made much easier at our place because we have such an amazing crew of people - self inspired and determined.

I know what you mean about the doubters of projects offered up to take on, they have all sorts of reasons to say why it can't be done or shouldn't be done:"where will we get the money"; "we've never done that before"; "we don't have the space"; "we can barely afford the planes we have" ....

But if you have the right people, then all that does is throw down the gaunlet and those "right" people take up the challenge to prove IT CAN BE DONE AND WILL BE DONE!

Not long ago, every idea of a project had talk of many obsticales; now, (and with great pride I say this) our guys just look at what is required and figure out a plan to make it happen and get it done! The transformation is amazing. So much so that the suggestions of things to do grows and not much nay-saying is ever heard.

Cheers and Thanks,

Bill.

P.S. Making grand progress on the Camel of late but not to the state where the pictures will tell much. Soon picts that will show it progressing grandly!

hank jarrett · 10 April 2006, 10:15 AM

Bill,
I would LOVE a Camel as a pet project! Unfortunately my job won’t allow nearly the time I would want to devote to it (note how long it took to get back to you on your message). I would like to carve out enough time to at least check over the stress analysis and am especially interested since I started a Camel design project using the Graham Lee concept (stand back and don’t look too close with an aluminum tube fuselage) several years ago. It never got past the preliminary design phase but I still think it would be a great design and only exceeded in popularity by a design from the Albatros series.
Sounds like you have already run up against the two top problems of stress analysis, 3-D objects with asymetric loads and lack of loads data. ;-) It’s fantastic if you have the original loads data from Sopwith. I didn’t know they ever generated that kind of data. I collect old Aero books so I have a lot of old design standard stuff too. You can actually get some really good stuff from the bridge and trestle design stuff from the era. Comparative analysis is still a valid method.
I’m “old school” and very comfortable with an Excel spreadsheet. We didn’t even have that when I started out. I was one of the first guys in school to buy an HP-35. We thought we were HOT STUFF! I still have a K&E Slip Stick but the HP is LOOOOONG gone.
Lets get together off group and see what we can do. If things go smooth at work this could be a lot of fun. Send me an Email at hjarrett@hroads.net (a buffer account to trap all the spam. I don’t worry about posting it. Gets about 150 junk hits a day.) I will respond with a good address and we can talk.
Hank

greatwarpilot · 24 April 2006, 08:59 PM

Work is progressing on the engine mount that will mate the AI14 to our Camel frame. Here are a few shots of the mounting ring being removed from the engine to allow for the modified original engine mount to be mounted directly to the engine case.

Involved removing the magnetos and the air pump to get the ring off, but its all back together now.

More details to follow as the mount comes together. With the triplane rebuild comming to an end it'll be all hands on the Camel!