Go Back  RCU Forums > RC Airplanes > Pattern Universe - RC Pattern Flying > Classic RC Pattern Flying
Reload this Page >

Reproducing a canopy for the Blue Angel

Notices
Classic RC Pattern Flying Discuss here all pre 1996 RC Pattern Flying in this forum.

Reproducing a canopy for the Blue Angel

Old 03-31-2006, 03:47 PM
  #1  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default Reproducing a canopy for the Blue Angel

8178 gave me the task of copying Ron Ellis's Blue Angel canopy for his build and he suggested I do a thread on it. Bearing in mind that how I plan to copy it has not yet produced a plug from which I can vacuum form useable canopy's I'll document the process as I proceed.

Ron sent me his MK kit canopy which just might be the last one in existence. And that carries a responsibility to use a process that will minimize the risk to it.

Here's the plan:

1. make a silicone female mold of the MK canopy (two reasons for using silicone are that the cure process creates very little heat which is less likely to warp the original – the second reason is that the mold silicone doesn't adhere well to much other than itself and Vaseline works well as a release for it).

2. make a male vacuum form plug using the silicone mold and urethane resin (plaster could be used but I have urethane casting resin on hand and I'm familiar with using it with silicone molds)

3. prepare the urethane plug and start pulling canopy's.

To be continued.
Attached Thumbnails Click image for larger version

Name:	Fd92716.jpg
Views:	80
Size:	30.3 KB
ID:	436624   Click image for larger version

Name:	Xs58927.jpg
Views:	68
Size:	5.4 KB
ID:	436625  
Old 03-31-2006, 06:06 PM
  #2  
8178
My Feedback: (17)
 
8178's Avatar
 
Join Date: May 2004
Location: Atlanta, GA
Posts: 4,348
Likes: 0
Received 7 Likes on 4 Posts
Default RE: Reproducing a canopy for the Blue Angel

Thanks Tony! This is pretty awesome.

Tony is making the canopies and Dan is producing the wing cores.
Old 03-31-2006, 06:46 PM
  #3  
rainedave
My Feedback: (1)
 
rainedave's Avatar
 
Join Date: Jul 2005
Location: Richmond, VA
Posts: 6,344
Likes: 0
Received 1 Like on 1 Post
Default RE: Reproducing a canopy for the Blue Angel

I think this is really great! There's a thread in the Kit forum pleading with Great Planes to bring back the Ultra Sport 60. Well, here's a group of people taking it on themselves to make it possible for other modelers to scratch build a classic design. For me, this is what it's all about. Modelers working together with various resources and areas of expertise. SAM works this way, in a sense. One guy makes the shut-off and DT timers, another guy sells the ignition components, and another guy has points assemblies, etc. I think the resources are around to build anything you want. It's great to see this.
Old 03-31-2006, 07:09 PM
  #4  
8178
My Feedback: (17)
 
8178's Avatar
 
Join Date: May 2004
Location: Atlanta, GA
Posts: 4,348
Likes: 0
Received 7 Likes on 4 Posts
Default RE: Reproducing a canopy for the Blue Angel

I saw that too. Once you have friends with the plans, foam wing design and manufacturing ability, a gold canopy and canopy manufacturing ability you are good to go! Shoot, that’s why X-acto is in business. Plus you get to cut the parts so they fit perfectly!
Old 03-31-2006, 07:49 PM
  #5  
jjpetro
 
Join Date: Aug 2003
Location: Lancaster, SC
Posts: 176
Likes: 0
Received 1 Like on 1 Post
Default RE: Reproducing a canopy for the Blue Angel

8178 and Tony,
This is great stuff!! I have recently procured a new and original Top Flite Kwik Fli III canopy by a very kind RC friend. I have been pondering which of the several methods to use to make copies for the upcoming reproduction release. This thread will help a bunch. Thanks for posting the topic.

Old 04-04-2006, 11:04 AM
  #6  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

I hope the thread will be of use. The process I'm going to use is by no means unique - it's just a collection of ideas I've gathered and used over the years. So there are other ways that will work too!

I started by cutting out the parts for the box that will contain the silicone mold material. The basic dimensions are determined by the canopy dimensions with some extra around the sides for the material itself. In this case the canopy measures roughly 13" L X 2-1/2"W X 2-1/2"H. So the box interior dimensions are 15"L X 3-1/4"W X 3"H.

The box parts were cut from scrap out of my lumber pile. The sides are 1/4" utility plywood and the bottom and ends are 1/2". There's no magic in these sizes, but the sides do need to be stiff enough to resist bowing when filled with silicone. The bow itself would not be a problem but it might throw off my calculations for how much silicone I need to mix.

Before I assemble the box I'll fit some pieces of blue foam to fill in some around the canopy so I can reduce the amount of silicone I'll need. The stuff is fairly expensive and there's no need to waste it.
Attached Thumbnails Click image for larger version

Name:	Wu61403.jpg
Views:	65
Size:	13.0 KB
ID:	438739  
Old 04-04-2006, 11:08 AM
  #7  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

I need to explain the piece that will hold the canopy in place on top of the box (which will be mounted inverted over the box when I'm ready to cast a mold).

I cut a hole under the canopy that will allow me to see the level of the silicone as I pour it. During the molding process I'll add water to the inside of the canopy as I pour the silicone around the outside which will equalize the pressure on the canopy to help keep it from deforming.

The OEM canopy is open at the rear and needed to be plugged. For this I cut and formed a piece of 3/4" hemlock to fit the opening. This plug will be glued to the canopy mount before the canopy is mounted. The portion beyond the canopy was rounded to help the plastic transition over the end without forming webs.
Attached Thumbnails Click image for larger version

Name:	Tr49060.jpg
Views:	56
Size:	6.9 KB
ID:	438740   Click image for larger version

Name:	Xs59067.jpg
Views:	59
Size:	21.1 KB
ID:	438741  
Old 04-13-2006, 01:17 PM
  #8  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Now that I'm over the flu I'm back on the project.

The forced 'vacation' time allowed me to reconsider the mold process. What was nagging me was that each time I estimated the volume of silicone needed even after packing the mold box, the amount needed seemed excessive. We just need a thin layer around the canopy and I kept thinking there must be a better way.

What I decided to do was to hollow out a chunk of blue foam to fit around the canopy with a gap of about 1/4" all around. Then the canopy on its frame could be laid on top of the foam block to support it over the cavity while silicone was poured into the gap.

The process was started by tracing an outline 1/4" larger than the canopy base on a piece of paper. The outline was then cut out and centered on top of a block of foam measuring 4" X 4" X 15".

Then the fun began hollowing out the foam. Messy, messy, messy. Fortunately the job goes quickly, the cavity doesn't have to be neatly finished and progress is easy to gage by putting the canopy into the hole. The primary routing was done using a Moto-Tool set on very low speed, followed by coarse sandpaper.

Next step is to mount the canopy on the plate.
Attached Thumbnails Click image for larger version

Name:	Ca82495.jpg
Views:	43
Size:	9.9 KB
ID:	444703   Click image for larger version

Name:	Ie98442.jpg
Views:	48
Size:	11.8 KB
ID:	444704   Click image for larger version

Name:	Qv55281.jpg
Views:	60
Size:	20.1 KB
ID:	444705  
Old 04-16-2006, 02:26 PM
  #9  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Before attaching the canopy to the plate I first glued the stopper for the rear of the canopy in place. Then the canopy could be set on the plate and – once centered – a pencil line was traced around the outside.

A rather large gap on one side of the canopy precluded using canopy glue (the gap was the result of the factory being a bit careless trimming the canopy). So a mix of slow set epoxy, fumed silica and micro balloons was used, mixed to a moderately thick consistency. In the area of the gap the thickened mixture was stiff enough to fill easily. A couple of pieces of tape held the canopy down lightly. (Ron will be happy I managed not to leave any epoxy prints on the canopy!)

After the epoxy had set, I noticed a small gap at the rear that had not been filled, so a second small batch of epoxy solved that problem.

To recap, the epoxy's function is:

* to hold the canopy in position (very little strength needed for that)

* to seal and fair the edges of the canopy so the silicone won't get trapped in an undercut
Attached Thumbnails Click image for larger version

Name:	Us53346.jpg
Views:	63
Size:	8.6 KB
ID:	446209  
Old 04-19-2006, 05:03 PM
  #10  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

To the ends of the foam 'box' I epoxy'd on scrap pieces of wood that will be used to support the ends of the canopy holder. Two slanted troughs were added along one side to allow topping off the silicone since the canopy holder covers most of the cavity.

The canopy was then coated with Vasoline which was buffed smooth with a soft towel. Vasoline was also wiped over the filler block at the back of the canopy – as thick as the silicone is, it will key into the wood pores and I didn't want that to happen on a part that has to slip out of the mold vertically!

Finally a couple of pieces of double sided 1/32" foam tape were attached, one at each end of the canopy frame, to hold it in place on the wood strips while the silicone set. (Since the canopy will be filled with water there is no tendency for it to float and so the tape just needs to hold the canopy centered in the cavity.)

Finally it was time to mix and pour the silicone. Two batches were used, each with about 6 oz of material. The first batch was poured into the cavity and most of the second. Then the canopy was lowered into it and water added to the inside of the canopy until it was full to with 1/16" of the top. Silicone was added via the troughs until the cavity was filled to top.

Then all one can do is sit around and wait.


If you haven't used this stuff, it's thick, slimy and very messy to handle. On the other hand it forms around almost anything and will replicate #600 sanding marks perfectly. And it releases mixing bubbles very well in all but areas where they can't rise to the top.

It's a curative silicone – as opposed to the hardware stuff which is a condensate silicone – and uses a curative additive. It's pure white and the curative is deep blue, which turns it a baby blue color when it's well mixed. Pot life is about an hour and it takes at least 24 hours before de-molding.

There are a lot of formulations on the market for mold making silicone, some with widely varying characteristics. I use a Silpak product I get from Fiberlay which is a local fiberglass retailer. It's farily stiff cured, yet has a lot of give without breaking. This makes it easy to get molded parts out of it that wouldn't be even close to possible with rigid molds.

Neat stuff.
Attached Thumbnails Click image for larger version

Name:	Mk26786.jpg
Views:	62
Size:	22.8 KB
ID:	447965  
Old 04-19-2006, 05:41 PM
  #11  
8178
My Feedback: (17)
 
8178's Avatar
 
Join Date: May 2004
Location: Atlanta, GA
Posts: 4,348
Likes: 0
Received 7 Likes on 4 Posts
Default RE: Reproducing a canopy for the Blue Angel

Great job Tony! Can’t wait to see how the mold looks when you take the canopy out.
Old 04-19-2006, 05:56 PM
  #12  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Me too! No matter how often I make molds there's always that burning desire to pull the parts and see what it looks like.

3-4 hours to go (added 4 hours to be safe).

Actually on a form like this even if the surface of the mold isn't perfect it's no big deal. One advantage of female mold forms is that surface bubbles make a molded part that has 'pimples'. And that makes it easy to sand them flush easily without losing the overall shape. On male molds bubbles mean lot's of filling before you can sand.

I like instant gratification (in this case anyway).
Old 04-21-2006, 10:55 AM
  #13  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Success!

I parted the canopy from the mold with my usual anticipation. As with any molding job like this with deep, steep sides, getting an initial movement of the plug (in the case the original canopy) is the hardest due to suction. A steady prying from both ends and the canopy came out quite easily. (The best process for parting rigid plugs that are having trouble coming out is air pressure by the way – but that was not an option here.)

The canopy is in perfect shape and the mold is just fine.

Next step is to cast a canopy plug for vacuum forming
Attached Thumbnails Click image for larger version

Name:	Ay75827.jpg
Views:	74
Size:	33.1 KB
ID:	448935  
Old 04-21-2006, 01:19 PM
  #14  
Kelsey_B
 
Join Date: May 2004
Location: West, TX
Posts: 427
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Reproducing a canopy for the Blue Angel

This is an interesting topic for me. May I ask where you get blue foam, and the Silpak part numbers for the silicone?
Old 04-21-2006, 01:36 PM
  #15  
Deadstik
My Feedback: (8)
 
Deadstik's Avatar
 
Join Date: Mar 2002
Location: Rougemont, NC
Posts: 1,301
Likes: 0
Received 1 Like on 1 Post
Default RE: Reproducing a canopy for the Blue Angel

Tony,

That is really fine work!!!! Can't wait to get a canopy....


Dan
Old 04-21-2006, 02:01 PM
  #16  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Kelsey,

I've had the blue foam - it's 2lb density - for several years when I bought a 4" thick 4 X 8 sheet. This mold was cut out of my largest remaining piece so I'm going to have to buy another sheet soon. (I also use it for making plugs for fiberglass molds.) Most insulation foam company's have it and home supply companies like Lowe's have it - but sometimes only in thinner thicknesses. They do in my area anyway.

The silicone is repacked for Fiberlay and so has their part number. Last time I looked the Silpak web site was under reconstruction unfortunately.

Here's the general spec for the stuff ... maybe you can use them to look for other sources:

Cured Hardness: Shore A 28
Tensile Strength: 520 psi
Elongation at break: 310%
Pot Life: 1 hr
De-mold: 24hrs

For canopy copying there is an easier way if the original isn't so dear. I'll post some suggestions for that shortly.
Old 04-21-2006, 02:38 PM
  #17  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Here's how I've reproduced canopy's that I could afford to take a small chance with. The process is usually fool proof and it's quick.

* Find a shallow pan that is larger than the canopy that will hold water

* Glue the canopy to a plate similar to the one I used with a large hole in the center. The plate should be long enough to rest on top of the pan securely.

* Fill the pan with water to nearly the top, leaving enough room for the the water the canopy will displace.

* Lay the canopy / plate over the pan inverted

* Fill the canopy with the casting material of choice (such as Hydrocal plaster)

* Top the water off as you fill the canopy, leaving it a fraction of an inch below the top of the pan

For a large canopy it is best to add water and casting material in steps to avoid stress on the canopy. This method not only virtually eliminates stress on the canopy from filling it with the casting material, it also acts as a heat sink during the cure.

It's a good idea to cast a couple of removable handles into the canopy mold to assist pulling it out of the canopy. I'll do that on the Blue Angel canopy which I'll picture in the next post.

This produces a ready to use vacuum plug and it eliminates the foam and silicone step I used for the Blue Angel canopy.

BTW this is not a new process - I found the idea a while back, thought it sounded reasonable, then found that it really works!
Old 04-21-2006, 03:06 PM
  #18  
Kelsey_B
 
Join Date: May 2004
Location: West, TX
Posts: 427
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Reproducing a canopy for the Blue Angel

Tony,

That is a pretty straight forward way to duplicate a canopy. I bet alot of the people following this thread have old, out of production kits, and want to be able to replicate the parts. I have several old kits that the canopies would be very hard to find. So I still like the silicone idea.

Thanks for the suggestions.

Looking forward to seeing the end result. Great work!
Old 04-21-2006, 10:42 PM
  #19  
Jim_Purcha
My Feedback: (8)
 
Join Date: Sep 2003
Posts: 1,917
Likes: 0
Received 1 Like on 1 Post
Default RE: Reproducing a canopy for the Blue Angel


ORIGINAL: tony-howard

I also use it for making plugs for fiberglass molds
Tony, you're going to have to do a thread on fiberglass mould work to educate the rest of us.
Old 04-22-2006, 11:07 AM
  #20  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Thanks for the compliment. Maybe sometime I'll do a thread on a project. I don't document as easily as some so putting together a thread is work.


Tony
Old 04-22-2006, 11:10 AM
  #21  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

Before casting the plug there's one more thing to do – I need a couple of 'handles' to help pull it out of the mold. The idea here is to embed 2 cap screws with nuts and washers in the plaster. When the mold and plug are apart, the cap screws will be unscrewed, leaving the nut and washer inside the plug.

I made temporary supports out of wood from my scrap box for a couple of 1/4-20 X 2" cap screws to be suspended over the mold. The slotted holes in the cross piece will allow each support to be slipped out from under the bolts when the cast is set (otherwise I'd have to cut them off the bolts – been there, done that!). The threads above the nuts were coated with Vaseline to help them unscrew later.

The picture gives a better idea of what's being done than the description.

Now it's time to cast the canopy plug for vacuum forming.
Attached Thumbnails Click image for larger version

Name:	Fd90904.jpg
Views:	57
Size:	13.9 KB
ID:	449414  
Old 04-22-2006, 06:26 PM
  #22  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

The mold has been filled with Hydrocal plaster and is busy curing.

More waiting!
Attached Thumbnails Click image for larger version

Name:	Ay74643.jpg
Views:	50
Size:	27.3 KB
ID:	449600  
Old 04-23-2006, 09:50 AM
  #23  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

This morning I removed the plaster casting from the mold. It came out quite easily using the embedded bolts as finger grips.

The plaster has to dry until it feels dry to the touch before prepping it further. Then I will remove the bolts, sand the base flat and dress the edges. I'll also need to fill a couple of bubbles that appear to be the result of my not having mixed enough slurry on the first pass. (I knew what the volume of the canopy was from having filled it with water during the making of the silicone mold. What I forgot is how many ounces there are in a cup when I was mixing the plaster. So I didn't mix enough and had to add a second layer. Rookie mistake!)

Overall, the plug looks good and should be ready shortly to make some canopy's.
Attached Thumbnails Click image for larger version

Name:	Ec89862.jpg
Views:	61
Size:	17.0 KB
ID:	450013  
Old 04-23-2006, 10:22 AM
  #24  
8178
My Feedback: (17)
 
8178's Avatar
 
Join Date: May 2004
Location: Atlanta, GA
Posts: 4,348
Likes: 0
Received 7 Likes on 4 Posts
Default RE: Reproducing a canopy for the Blue Angel

Looking great Tony! I can clearly visualize the plastic being sucked down over the plug already.
Old 04-25-2006, 09:31 AM
  #25  
tony-howard
Thread Starter
My Feedback: (224)
 
Join Date: Sep 2004
Location: Monroe, WA
Posts: 361
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Reproducing a canopy for the Blue Angel

The pull bolts came right out without a hitch - they were finger tight . However the plaster took longer to dry than expected. And the mistake that caused me to have to cast a second batch of plaster resulted in the base of the casting having lots of bubbles in it (I suspect some of the water in the second batch was absorbed by the partially setting first batch which didn't allow it to expel all the bubbles produced by mixing).

When I cast the plaster I filled the mold as high as possible even though the OEM canopy had some extra material at the base. This left a flanged area that is now faired to the basic canopy contours. And the bottom has been planed fair. A Sureform file was used for basic trimming, followed by final sanding. At this point only a couple of tiny bubbles remain to be filled with spackle.

(The lightweight Hydrocal I bought for the project when my old supply of regular didn't look good is softer than I would like. So I'm going to put a coat of thinned polyester resin over the surface to help protect it against 'hangar rash'. Polyester is the better choice vs epoxy because it has better heat resistance and sets faster.)

Despite these minor irritations, the plug should work just fine.

Attached Thumbnails Click image for larger version

Name:	Tr49491.jpg
Views:	62
Size:	8.9 KB
ID:	450819   Click image for larger version

Name:	Pk30995.jpg
Views:	59
Size:	9.8 KB
ID:	450820  

Thread Tools
Search this Thread

Contact Us - Manage Preferences - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.