Steam bending

[Eric The Viking]

I was looking for dinghy footage (see a thread in the Design forum), and came across this:

http://www.britishpathe.com/record.php?id=171

It's rather fun.

I did a lot of dinghy sailing as a youngster and always admired Fireflies - sometimes painted on the outside (for smoothness), but with all that beautiful wood showing on the inside. There's some 'interesting' use of machine tools too (don't tell Steve Maskery!).

IIRC, Heath's "Morning Cloud" series of bots were built in a similar way (laminated), but not steam cured - too big for that! I don't know what WW2 vessel had that technique used on it though - boat, or aircraft possibly.

Enjoy.

E.

PS: just found this: http://www.britishpathe.com/record.php?id=880. It's off-topic, but I learned to sail in one of these, about eleven years later!

 

[twothumbs]

I think the MTB's planking was laminated but don't know if they were steamed. The Mosquito was timber construction with a similar veneering, plywood aero frames I think. Aerolite glues were developed at this time. Google should confirm if what I am writing is wrong or right. Forgotten which sports car had a ply chassis. Not quite your question but related.

 

[Eric The Viking]

I think the MTB's planking was laminated but don't know if they were steamed. The Mosquito was timber construction with a similar veneering, plywood aero frames I think. Aerolite glues were developed at this time. Google should confirm if what I am writing is wrong or right. Forgotten which sports car had a ply chassis. Not quite your question but related.

It's interesting. I knew Mosquitos were ply, but I didn't know about the skin. There are several being completely reconstructed presently (one in Australia*, I think), because the ply has de-laminated over the years.

Could have been MTBs too - would have made the hull very light and therefore fast.

E.

* wrong! null points! It's in NZ: http://www.mosquitorestoration.com/

 

[hanser]

MTB's were double diagonal planked -2 skins of planking, one over the other on the diagonal and fastened to the frames. Not glue lam. The method provided a strong hull. Bear in mind an MTB could have 3 engines providing a total of around 3000hp and capable of nearly 50 knots.

 

[twothumbs]

I knew a chap who served on the MTB's in the Med. He would have been aged about 20 then. Never spoke about it other than to say because they were so fast (your 50 knots) they were thought of as the bees knees, or at least thought they were. He seemed to have good memories of the Eastern Med. By comparison a fast freighter crossing the Atlantic had to be capable of doing 15 knots to cross unescorted. Slow freighters would do under 10 knots. So MTB's were very fast. Pioneering days then.

 

[AndyT]

Nice film.

This link is to a 'How it's made' video of cedar canoe construction showing very similar techniques - thin strips stapled/glued together:

http://www.youtube.com/watch?v=PcyEa0bgKxY

Apart from the background music, strikingly similar films in some ways.

 

[colinc]

Hi,

a bit of a topic drift from steaming for boats, but if anyone's interested in the Mosquito's construction I have a photocopy of a late wartime article which goes into a lot of detail about how De-Havilland built them. It is very interesting so see how the fuselages were made as two shells split vertically and then fitted out with most of their systems before being spliced at the seams. It's the best I have read. I can scan and email it to anyone who's interested.

The articles describes how DH originally made the spars from solid but were then forced to move to laminations as top quality material (sitka spruce) became harder to find. Apprently they developed a system for sawing laminations to a few thou accuracy to reduce waste to the absolute minimum.

I have more than a passing interest in De-Havilland's methods as I've given up making coffee tables in my spare time and am helping out with this: http://www.cometracer.co.uk

I'd love to know more about that as we're into similar territory with the Comet's spars and good wood is even harder to find these days. Here's me contemplating cutting some big baulks of spruce into laminations for the spar: http://flic.kr/p/9e2iot

The Comet upper and lower wing surfaces between the front and rear spars are 2-3 layers of diagonally laid spruce strips too, so not unlike boat building technology. The rest of the structure's spruce and ply.

By the way, if anyone's is interested in aircraft and wants to take a look, visitors are welcome (particularly if they bring biscuits or cake for the inevitable tea break while we chat). Experienced woodworkers willing to lend a hand will be particularly welcome!!

regards,

Colin

 

[Eric The Viking]

Love the push-stick

Yes please, if you've the time to scan the article, I"d appreciate a copy. PM sent.

 

[AndyT]

Colin (and anyone else!) - I've just been reading a book "The New Science of Strong Materials - or why you don't fall through the floor'. The author, JE Gordon, worked on wooden aircraft construction during WW2. It's interesting to see how the fundamental research into what was strong and what was not only happened under the urgent requirement to build more planes, and build them quickly. It's an excellent, readable book (though apparently out-dated by lots of materials science work in the last 40 years).

You should be able to read the chapter on 'Glue and Plywood - or Mice in the Girders' at this Google Books link.

But if you're building a new wooden aeroplane I hope you know all this stuff!