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Old Feb 22, 2009, 08:33 AM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
Sounds good.... I picked up the plastic sheets for the canopy and I got the pilot! He will be viewing some refresher training films to re-orientate himself with the P-47
Four our benefit.... here is an original film how to assemble the p-47.
P-47 Thunderbolt Assembly Part 1 of 4 (9 min 59 sec)

P-47 Thunderbolt Assembly Part 2 of 4 (10 min 1 sec)

P-47 Thunderbolt Assembly Part 3 of 4 (10 min 1 sec)

P-47 Thunderbolt Assembly Part 4 of 4 (9 min 53 sec)


Mike
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Last edited by tr6world; Feb 22, 2009 at 09:05 AM.
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Old Feb 25, 2009, 12:31 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
Vacuum Forming

Amazing..... Fun..... Easy...... I am looking at a sweet looking p-47 canopy that I molded using vacuum form techniques. This had to be one of the more "instant" gratification parts of this project....

Mark was working on the framework of the canopy as I was working on the hatch seals (more on that soon). It was time to make the plastic part that would be the P-47 Canopy. Did you know that vacuum forming can be done at home in your kitchen! (don't let the wife find out )

Here are 4 components required to successfully plastic formed parts:

1. Mold
2. Plastic Sheet secured in a frame
3. Vacuum Box
4. Practice & Patience

About the Mold
First the mold of the canopy shape was made using basswood. See Post # 101 http://www.rcgroups.com/forums/showp...&postcount=101 . We pick up from there. Now the mold is ready for details. The framework (greenhouse canopy) that makes the razorback unique uses an aluminum frame holding the glass sections in place. We used 1/32 thick ply strips to create our framework effect on our mold. (see pictures below)

Next comes the fun part.... I have included a video of the process.

About the frame
using .030 thick plastic sheeting in a 24 X 24 square purchased at the prop-shop, we cut the plastic to fit into a rectangular frame. It was secured onto the frame using tape. i have seen other devices used to make frames like aluminum screen material or wood strips.

We placed it into a baking oven elevated on 4 drinking glasses. Keeping a close watch, the plastic began to sag. Once it sagged about 1 1/2 inches, it was time to pull it out and set it on the mold.

About the vacuum box
Its one thing to heat up a plastic sheet and place it over your mold. It is another for it to be pulled down with air suction. Using a regular house vacuum with a hose attachment, the hose attached into a box made out of plywood. It was completely sealed and the only holes in the box were directly around the perimeter of the mold. The mold was epoxied down onto the box. (see pictures)

Practice & Patience
We attempted to make our canopy 5 times.
1st time - I got in the way when Mark was trying to mold and the plastic cooled to fast before the vacuum was turned on.
2nd time - Complete success. Mark made a perfect canopy
3rd time - Disaster. I (Mike) laid the framework onto the glasses, but my piece of plastic was larger that it was suppose to be plastic melted onto the glasses that elevate the frame in the oven. Mark didn't kill me.
4th time - I got better, but my oven mitt was stuck under the frame and I didn't push the frame down far enough. Close, but no cigar.
5th time - Plastic heated a little longer this time, nice and soft and I nailed it. The vacuum sucked it right down and I got a perfect canopy. (Now I have a spare )

The end result was remarkable! I have to say, the quality of the end result really depends on how good the mold is. I could see that any bumps, ripples or defects would easily be transferred from the mold/die to the plastic canopy (finished product) As a matter of fact, we used scissors to cut the strips of ply for the canopy frame effect. The scissors had a very very slight serration on the blade. Not really noticeable to the eye. This serration showed up (if you look real close) on the end result you can see it. I mention this so you can get an idea of how easily flaws can appear. Even wood grain will be transferred from the die to the vacuum form part.

This was a real fun part of the building process and if this has ever kept anyone from doing a scratch project, reconsider. Making your own plastic parts is not rocket science, it just takes some practice and the right tools.

Here is the video:
Mike's P-47 Thunderbolt Canopy (0 min 19 sec)



Mike
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Last edited by tr6world; Feb 26, 2009 at 10:15 PM.
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Old Feb 26, 2009, 08:38 AM
I eat glue
Canada, NS, Yarmouth
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Looks like a commcercial for the ove glove
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Old Feb 26, 2009, 04:15 PM
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Sydney, Australia
Joined Jun 2006
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Really inspirational guys. Making plastic parts has always put me off, but to see it done with a household vacuum cleaner really allays those fears. Well done. Perhaps melting plastic all over the kitchen is in my future now...
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Old Feb 26, 2009, 09:54 PM
ARFs make me BARF
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United States, MI, Roseville
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Mike, .030 plastic
Mark
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Old Feb 26, 2009, 10:12 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
Opps I will edit my previous posts regarding the plastic thickness.

Gree, as far as mess goes, there really wasn't that much of a mess..... except for the melted plastic on the glasses thing....... Mark lined the bottom of the oven with tin foil to be sure and protect the oven and heating element. The whole thing was pretty amazing.

Here is one more picture of the canopy just coming off the mold.

Mike
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Old Feb 26, 2009, 10:31 PM
Limited experience so far
Tromsų in Norway
Joined Oct 2008
104 Posts
Hello

Thanks for an excellent building thread, really an inspiration, the instructional videos are excellent, and the link to make your own electric foam cutter was geat. I`m a 36 year old guy from Norway that have not been in the hobby for 18 years. I find this thread really interesting, especially the fact that you build mostly from foam, when I was in the hobby it was almost only balsa, and few planes used electric power. I think the plane looks beautiful. I especially like the curved fuselage, this model really looks like a plane. I have done some scale projects earlier from plans. Last build vas an airtractor for glow engine. I wonder if the plans of this airplane will be avalable?
I look forward to see the forward progress!!
best
Eystein
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Old Feb 27, 2009, 07:28 PM
ARFs make me BARF
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Well, if there is interest I can make some rough drawings available for download that would be enough to build from.

Mark
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Old Feb 27, 2009, 10:29 PM
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ediaz's Avatar
Orlando, Florida
Joined Nov 2004
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Mark,

I'd be interested in your drawings. I have your P-40 drawings and I really liked your approach. The P-47 has been on my list to builds for some time and this has thread has really inspired me to dust off the work bench.

Thanks,
Evelys
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Old Feb 28, 2009, 07:27 AM
ARFs make me BARF
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I'll keep that in mind. The drawings nood some perfecting at this point, so we'll see how much interest there is and how much time I've got
Mark
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Old Feb 28, 2009, 06:33 PM
Limited experience so far
Tromsų in Norway
Joined Oct 2008
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Quote:
Originally Posted by mrittinger
Well, if there is interest I can make some rough drawings available for download that would be enough to build from.

Mark
That would be great!!
Best
Eystein
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Old Mar 02, 2009, 12:33 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
One last pic of the canopy is posted here after the flashing was cut out. It will look real nice once painted and mounted onto the fuselage

Mike
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Old Mar 02, 2009, 12:51 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
Hatch Seals

Because we are working with Foam we want to trim out any exposed foam before the fiberglas process takes place. This will help give us a nice finished look and a great fit. It will also provide more strength and rigidity to both the hatch and the fuselage. The hatch to the battery & controls is on top of the fuselage in this design..... much like the parkzone corsair.

The edges of the hatch and the opening are trimmed out using 1/64 plywood. Thin strips are cut being careful to pay attention to the direction of the grain. Like any wood, cross grain will flex, with grain provides the rigidity.... because part of the hatch is curved, we wanted to take advantage of this by cutting the ply across the grain where the curve would be.... See picture. I know it is a bit blurry, but you will get the point.

I have not finished sanding and smoothing these spots yet, but I wanted you to see what they looked like "as is" after the glue had dried... Because we added material to the foam, we needed to lightly sand off a little foam along the surface of the hatch and the opening. This provided us an opportunity to make the surfaces smooth and flat.

Once the sanding is done to these surfaces, they will be ready for glas.

Mike
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Old Mar 02, 2009, 03:07 PM
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1/64 ply Mike. Canopy looks good too. Should be really cool with painted foil and weathered.

Mark
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Old Mar 03, 2009, 10:06 PM
Mike Brinker
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SouthEast Michigan
Joined May 2008
555 Posts
Wing Sheeting Prep

We began building the wing back in post #100 which included using foam wing cores for our wing with the intent to sheet the wing with balsa. Sheets of balsa will be used to cover the foam. We are using (2) 6" X 48" balsa planks that are 1/16 inch thick and (2) 4" X 48" balsa planks that are 1/16 inch thick for our supplies. We cut all of the planks in half so they are 24 inches long each.
Are you confused yet? Our goal is to have four 10" wide sheets 24" long. So we took a 6" plank and a 4" plank and glue them together to form a 10" X 24" single piece. This will make the top or bottom sheet for 1 side..... So, we need to make 4 of these.

Depending on the quality of the balsa you get, the sides may not be perfectly straight. Mark showed me a cool technique to get a perfectly straight edge to mate the two pieces.... see the picture below. Here is the technique:
slightly overlapping both the 6" and 4" pieces with each other (about 1/4 inch), use a straight edge yard stick or something that is perfectly straight and cut through both the planks. Trimming off about 1/8" of balsa. This will make both ends have the exact same cut and perfectly match up....

I took both of those pieces, butted them up against each other so there were no gaps and used masking tape along the entire seam of one side of the planks to hold the two pieces together. It acts as a hinge. I fold the two pieces open and used that sig-bond yellow glue (it sands a lot easier than CA), along the entire seam, folded (joined) it back as a single plank and then covered the entire seam that had not been taped yet...... now there is glue in the seam and it is drying with masking tape holding it together....

The pictures will do a better job explaining.... Sorry for the long explanation guys, but some of us have never done this before and it is all new to us. This is for their benefit and mine.

Next, once the glue is dry, we will glue the sheets to the foam.
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