Sopwith Corner

9 February 2005, 02:50 PM

Good luck with the steam box operation! If you get a lot of crushing on the compression side of the bend a metal backup strap will help. It needs to be clamped securely to keep the wood in tension. I have had better luck using household ammonia mixed with water. (not sure on percentages) but it made the wood wrap around the mould with out much trouble. (have not tried it with spruce yet.....

Best of luck to you!

I think there were several posts on bending when Achim was having trouble with the DVII cap strips.... It is best to experiment with methods and find what works best for you.

Dave

AchimEngels · 9 February 2005, 08:57 PM

Please do not laugh now, since this is not a joke

But if you do not need too tight radii, just experiment with some pieces of waste and wrap them around a hot stovepipe.

I was employing this method successfully for wooden stringers of up to 1/2 inch of thickness. You can even bent plywood that way to a certain degree.

The stovepipe needs to be as hot as not yet to burn the woood (and your hands) and the pressure needs to be minimized. You will note that it bends around with little force applied.

The trick when bending wood is aplying heat to the wood. Water in whatever way (whether you water the wood or steam it) is just a good medium to bring the heat into the wood. It is not neccesseseraly required to work with water or steam.

Give it a try.

Best

Achim

nomma · 9 February 2005, 11:22 PM

Thanks for your advice, guys! And also thanks for the DVDs which arrived today, Achim. Both interesting and great fun to watch!

The only tight bend of the capstrips is in the front, so I first designed a shorter bending jig just for the front 30 cm. I used the plain hot water method without ammonia, soking them for three hours, which worked very well (spruce). But then I realised that it wasn't harder to do it "the right way" and bend the entire capstrip over its entire length. It just feels better not to use any bending force at all when glueing. That's why I am trying the steam method.

If it works, I will use the same system for bending the longerons.

By the way - if anyone wants a detailed IKEA instruction for how to build a British WW1 aircraft, buy a copy of the book "How an Aeroplane is Built" by Stephney Blakeney. You can get it from WW1 Aero.

Mr Blakeney was probably a manager at Sopwith, because he describes in detail how a Sopwith type aircraft is built, including which tools the factory needs. He tells you everything in detail, sometimes even more than you need

for instance that for steel sheet thinner than 18 G even "girls" can bend, and that the foremen who don't realise the importance of quality are idiots and should be fired... Great reading!

Best regards,

Magnus

nomma · 12 February 2005, 02:27 AM

Hi all,

Does anyone know a supplier for mild steel sheets and/or tubing in the UK? If not - maybe in the US?

I have considered using metric thickness steel sheets, but I just realised that the increased thickness of the brackets will affect the width of the bracing wires fork ends. So, at the end of the day, going for Imperial sizes makes life easier...

Best regards,

Magnus

nomma · 18 February 2005, 10:50 AM

Finally a day for building...

I first tried a steambox out of wood with a hose connected to a kettle. Disappointment - didn't work. Not enough steam. Then I did what I should have done from the beginning - ask my mentor Mikael Carlson how to do it. So the new one became a Spiro-tube (ventilation tube) directly connected to a larger pot. Wow...could have driven a steam engine...

Also, the condensation flows back into the pot. Smart.

Then I started routing out the leading edges. No problem really. I think I have spent ten times as much time thinking about how to do it, as it will really take to produce them... Lack of experience costs... Next step is to cut the rounded front edge of them, and finally cut out seats for each capstrip. By the way - almost all the spaces between the "knobs" are slightly different. It is British, of course. Why make it simple?...

Pictures:

1) Steam box Mk I. Didn't work
2) Steam box Mk II. Did work
3) Jigs for bending the capstrips. Complicated shape of the lower one (which is the one on top here)
4) First cut of nosing
5) First cut of nosing detail

nomma · 19 February 2005, 10:30 AM

Just wanted to show you how much (little) wood is left after routing the stab leading edge. Scary... I hope that someone did the math on this one 90 years ago...

Best regards,

Magnus

wolfenbill · 20 February 2005, 08:18 AM

Yep, that's not much wood. Just goes to show you that the stresses are spread out over a large area. But it's stronger than you think. Just wait until you inadvertently walk into the leading edge with your head leading the way. Your head will lose.

20 February 2005, 08:35 AM

I am very happy to see the progress you are making on the Pup project. I would like to make you an offer.
I am Roger Freeman from Old Kingsbury Aerodrome, and as you may have noticed, we are involved in several projects, and I am very familiar with what it takes to build these old aircraft. We have recently added a Mazak laser cutting machine to our outfit, and one of the things that I want to do is work with other builders in cutting fittings for them. If you are interested, we would like to talk to you about cutting your fittings. We have also developed ways to make formblocks with the laser that will greatly cut the time it takes to form difficult parts such as the engine mounts.

The bottom line is that we can cut your fittings faster, more accurately, and above all cheaper than you would ever imagine. I hope that some of you builders out there will let us help you on your projects. I want to see more of these fine old birds back into the air.

By the way we can also cut wood!

nomma · 20 February 2005, 01:38 PM

Hi Roger!

Yes, I am interested in having the fittings laser cut. I have already made some initial arrangements with a local company, but I am having difficulties finding the correct steel.

Would you be able to get mild steel? 1020 for instance?

I'll send you a private message about this.

Today I tried a method that is taken straight out of the Blakeney book. I was going to taper the compression struts of the wings. I used the spindler with a large ball bearing at the bottom. Then I just built a simple jig where I had the strut stick over the edge at the requested angle. All wood outside the jig is simply spindled away. After some trial and error it worked really good!

To Wolfenbill: Yes

I usually hit my head on the Cub prop at least twice a day, so I better get myself a helmet after assembling the wings...

Best regards,

Magnus

jumpinjan · 20 February 2005, 03:16 PM

Roger,
Could you provide examples on metal thickness capability and what do you need to input into the laser cutter? I'm referring to what we need to provide (data/drawings, etc) to you.