Discussion in 'Aircraft & Aviation' started by barry, Nov 15, 2004.
Looks like a winner Barry.
Great stuff, its going to be hard for you to figure out which to enter in the comp
Can't wait to see her finished
What a great bird. You did a wonderful job putting her together Barry!
Corsair when it's not raining
I lied I had some unexpected building time, the rain stopped before darkness fell so I rushed out into the fresh air to get a pic.
Sorry the canopy is not stuck down but it looked better than a hole in the fuselage, and it still needs some fairings and touching up.
I am hoping someone out there with the right knowledge will tell me how to convert the paper canopy into a mold for a plastic version and as I own an old microwave oven, can I use that to heat the acetate. I promise you can all have a laugh when I try it.
Mareks kit certainly gives the bulky impression of the original and as I tried for years in early life to carve one from wood without success it's good to have a model at last.
Belatedley size is about 40 cm wingspan with a length of 30 and it looks impressive sitting on top of the TV.
One last tip Ashrunner put up a web address for the Kate bomber which has an excellent front view drawing on it if you blow it up to full size on your screen it is a good way of checking the prop blades are set evenly.
Now I am getting the shakes for some salt water again but I've now got hooked on this side of the hobby.
Looks fantastic, so much so I went and bought a copy :lol:
Look forward to the canopy cooking!
Outstanding work, Barry!
You did a real bang up job of her, mate!
Having the wings fold would have been great, but I agree it would have involved quite a bit of work. I saw a build on the sister site, there this fellow Malo is building the GPM TBM-3 Avenger with folding wings:
Seems a pretty involved job of making them foldable. :?
I just love the way she came out, Barry!
I do hope you update us once you've made plastic ala Barry for the canopy. :lol:
It really did turn out very well in the end, didn't it. Congrat's - Leif
There's a good article on canopy forming at
(on a link from Ken Hornes links page)
Where it says says
"Step 1 - Take a block of medium to hard balsa and carve to the shape of the required canopy. This is the hardest part of the whole process - it takes time, and you make lots of mess! "
- this is definitely true - the rest is easy.
I've also seen it suggested that you can build the paper canopy, fill it (plaster or car body filler or summat) and sand to make the shape. Not sure where though.
I've never tried a microwave for the heating and don't know how it would go. More usual heat source has been an electric fire (radiant bar heater for non Brits) or a hot air gun does it well. Also as suggested on that link.
Care with any method of course. (Make sure you're home alone and can air the place afterwards )
And anyone looking for large quantities of info on Vought aircraft might also visit
lots and lots of it.
That was a very good tip & link, Maurice. Thank you! Feels almost like I could do it, too. Nice suggestion to build it in card, fill it and sand it. Would provide the right amount of reduction in size, to compensate for thickness of canopy. Brilliant idea, which I have duly made a note of, including link to this post.
Thanks for the links the kind words and the tip on the cardboard mould tool (I had the feeling I had read that somewhere too). Somedays I think I'm barmy trying daft things but it stops you getting senile.
I have another question for the experts when building a fuselage with a long cockpit like a Stuka do you cut the aperture before or after forming the fuselage sections.
Well done Maurice you can use the cardboard canopy as a rough moulding tool. I stuck a square of paper on the back
a to stop everything running out
b to get the back end somewhere near the required width
I had no vaseline so I pinched a dab of my wife hand cream and used that as a release agent and it worked very well. The cardboard is a oneshot mould as you can see even with the awful pictures.
Mixed up some Polyfilla (west side residents wall crack filler) fairly stiff mix and pushed it in with a wooden spatula (wooden knife from Wisley Botanic gardens) and left it to dry for about 8 hours.
The moulding card just peeled off leaving to my amazement a working plug needs some filing and a little more filler. It would not be good enough for vacuforming but glued to a large nail or screw ther is a good chance it will be Ok on plunge.
So as far as I am concerned steps 1 and 2 work have to see if I can get the right heat into plastic etc.
OK I should have made it a bit longer and deeper but it is not going to cost much to try again and it will do to practice pulling the plastic
I hope so because I am useless at carving wood
Standard domestic microwave ovens are designed and optimised to transfer energy to water - the oven frequency is about 470 MHz which is a spin resonance of water molecules. You may get some heating of plastic in a microwave but it isn't going to be very efficent.
It's possible to construct a microwave heater for just about any material but the microwave frequency has to be optimised for the material and (in part) the oven geometry.
I have a vague recollection that RF welders for plastic operate at around 25 MHz, (A quick Google gave a frequency range of 13-100 MHz)
Good point Charlie it's back to the toaster
Thanks for the explanation Charlie, I knew there must be a reason for why I thought microwaves would be crap in this context. Come to think of it I've only ever welded plastic using (very) hot air.
Whatever the source Barry the heat needs to be applied gently to allow for the poor "thermal conductivity" of plastic. The outside can be on fire before the inside is even warm so the heat needs time to soak through, even on thin stuff.
Next time with the mould you might try using PVA instead of a release agent and fill while the PVA is still wet. Up to 24 hrs to dry and it should then be possible to sand the paper off and might give a smoother finish. Just a suggestion - all usual disclaimers. :twisted:
Bin a while since I was at Wisley - shades of a previous incarnation. 8)
Thanks for all the suggestions. This is how the first attempt came out and in case anyone is interested my conclusions are
a Build the cardboard canopy as carefully as possible adding enough extra size to allow for cutting the canopy from the mould (1/2")
b Use some thing like plastic wood so you mould it under the cardboard
c Give it plenty of time to dry then sand it to final shape and stick to a piece of wood or something which will give you about 6 inches of pull it will need to support most of the length and width of the moulded cockpit.
d an old toaster is the ideal weapon for a heat source (it would not take long to burn one out if you are not careful, and empty the crumb tray before you start, otherwise the fire alarm will sound to add to the confusion). I have read that a night light candle is also good for heating plastic.
e get yourself kitted up with the wifes oven gloves you will need them
f cut a suitable chunk out of a plastic dish or strawberry container it does not matter if it has fancy mouldings in it.
g grasping the plastic in both mittened hands hold it about 6 or 7 inches above the toaster and keep moving it about. At the same time gently pull the ends until it takes out the pattern in your bit of rescued plastic and stretches slightly then pull gently till it goes flat.
h have the cockpit block immediately to hand and as fast as you can pull down over the mould.
If you are lucky it will take up the shape required. I have put a couple of pics up to show the first attempt that half worked.
Great thing is if you make a cods of it all you have to do is reheat it and try again the current one was the 6 th reheat. It's not right but I thought I would try it out against the model if it was glued down it would look better than it does.
To be really lucky you need Fishcarvers skills, but for those of not so adept this way looks like it will work.
I'm sorry but I really hate blue paper canopies on planes.
Sorry the canopy metal was thrown together and fits where it touches
Thanks Barry! You've shown that's its really possible. Good how-to as well! - Leif
Good show! Nice to see the gumption to continue on in the abject face of repeated failure to achieve perfection! The world's greatest learning aid!
Some suggestions from the paper stretching days;
1.) Waterproof the card "form" with lacquer, shellac or dope before casting.
2.) Spread a thin layer of Vaseline (petroleum jelly) as a mold release.
3.) Use Plaster of Paris (PoP) as the casting media. Add the powder to the water using a sifter. This insures a lump free plaster. It takes a little longer but is fail proof. PoP is low cost and available in all hardware and home improvement stores.
4.) Strengthen the surface of the thoroughly dried casting with shellac, lacquer or dope.
Best regards, Gil
Well, that came out great, Barry.
I really appreciate your going through the process and giving guys like me a superb education on making canopies. I also don't like the printed glass on planes and this process at least gives me an alternative to try next time around.
A great how to mate
The whole idea is a very good one and you show it so well.
I think I will order a new toaster now just in case :lol:
Keep at it
Cockpit canopy saga
Well this is effort number 2 at moulding the cockpit. This time I took a lot more care in making the mould I used UHU instead of white glue on the cardboard canopy and then added strips on the lower extensions to give some added strength. I then painted the inside of the canopy with pva glue to add more strength.
I put Vaseline on as a release agent again. The moulding did not have the chop off as in the first version more a gentle slope to take some the strain of pulling the plastic (my fingers are not so good so you may not need to worry about that). The strengthening worked because I still can reuse the cardboard mould again.
I should have taken more care to get the base as flat as possible because in spite of covering the plaster cast with shellac I finally bust the front off the mould, luckily after I had got a halfway decent canopy. Thanks Gil all the suggestions helped.
Maurice made mention of the poor heat conductivity in plastic so accordingly modify the original instructions to when it pulls flat to when it pulls flat leave it over the heat just a bit longer to it gets really floppy. This because however fast you move when you get to the mould it will be just floppy enough it takes time to heat up but it cools a damn site faster.
Looking through the internet instructions I came accross a guy who had built a box with it's own heating elements in it and a compartment with the mould mesh and vacuum cleaner connection. When the plastic had heated he then flipped the hot plastic over to the moulding side with vacuum running. Quite beyond my skills I'm afraid.
It is a bit of fun to try and it costs little the plaster is cheap the plastic is salvaged from the supermarket packaging and you know the canopy is the corrrect size because you can check it out using the cardboard mould.
Lastly this is a black art you can only do it by experience but as I said before do not get the plastic close to the source and you can keep stretching the stuff for a lot of trys
Sorry it's the same set of pictures again and to be honest they are a bit flattering but then I was only going for the 2 foot standoff. I suppose I had better finish the details like the guns and aerials now.
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