Spitfire wings at AREA-52


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THend
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Post by THend »

Next phase, let's make a fuse! I tried to get this going last week on Friday, but details details details...

Anywho, we were messing around with the motor mount. I made one of HDPE and one of high quality ply. The problem with HDPE is that it really doesn't bond with anything real well, but it is great for a mechanical bond. So, we opted to use the wooden mount after all, at least for now until we figure another way.

Here is a shot with mount and a motor. I made a jig for the Mag 15 that will locate the mount holes. Adjust your motor back and forth, and then place the jig to get perfect drill location. Once we know where this sweet spot is, we may just pre-drill the holes on the CNC when we cut the mount. One big factor is the type of spinner one uses as it will change where the motor gets mounted.
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Here, the two halves have been cleaned up, and with hole drilled and ready fot the 1/4-20 hardware that will hold the two halves together. I may have forgot to mention, but before you layup the second half of the mold, you need to make KEYS so that the mold halves will go back together and align. Probably very obvious, but maybe not. If you don't key the mold, then you end up doing each half individually and then seaming them.

Waxed several times and sprayed with PartAll. Ready for glass and resin.
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To keep the time down, I pre-cut all of the glass I am using. I made a cloth template by laying cloth into the mold, and then transfered the pattern onto some plastic. I was working alone today, so time was very critical. If you have two guys working the resin/cloth, and guy available to mix resin and cut glass GREAT... but I think being ready is key.

Wetting out the glass
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Here, both halves are now wetted out and trimmed. In order to "seam in the mold", the mold must align with some sort of keying, and then you need to trim the wetted glass to facilitate the join.

What you have to do is cut the gelling glass/resin on opposite sides, as in upper and lower. Hard to see on my left, but you can see the upper half of the fuse in my right hand is trimmed about 1/2 inch above the mold. Do the same on the lower surface, and then put the two halves together. Be careful to offset each half so that the material above the mold will go into a void in the other half. Then slide the two halves until the keying aligns the mold.

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Not done yet! Now, with the two halves slid together and keyed, install some hardware to prevent the two halves from moving around. Some folks use clamps, I did once, and it gets heavy fast. The reason I like the nylon bolts is that nothing will really stick to them and they are light. Why light?

Now you need to use a wire with washers that spin, and reach down into the fuse cavity and roll the seams. This is NOT fun, and can lead to pulling the glass off the mold. It was too late for me, but I remembered some guy saying how he used large steel balls to roll around in the fuse and set the seams. I am going to try this next time. Another trick, and I may opt for this as well is to just cut off the very rear of the mold. If you plan on using that area for an elevator attachment, then why not use it to set the seams too?

Here is the shot with the wire and washers. Note you need to cut out the saddle area in the mold and then trim off the gelled resin/glass to allow access into the fuse cavity.
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Well, now it is back into the EZ bake oven to cure. I'll pull it apart tomorrow night after work. I am so new to this, so I am not going to hang my hat on the first one, at least it is a combat plane and not a beauty pageant entrant.

Be back tomorrow night with the results! [:D]
THend
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Post by THend »

BTW, not being an expert, my time from first resin mix to going into the EZ bake oven was 2 hours 15 minutes. I know for a fact I can get that time down a bit.

I am also using Polyester resin over Epoxy due to costs. Epoxy for some reason is much more expensive. I don't know much about the Polyester resin, but I do know it likes the EZ bake oven and an over night stay in the oven.

The few Epoxy fuses I've seen made could be popped in as quick as 6 hours, but most folks let is set overnight. You can EZ bake epoxy too...
gsjames
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Post by gsjames »

Outstanding Terry! I'm really enjoying watching your progress. While looking at your Spit, I started thinking about your Mako. Is it practical to make a semi-permanent fiberglass center section for the engine, bladder, radio, etc and then have plug-in wing panels? That way you could replace busted wing panels at the contest if the need arose. I've been thinking about this possibility for quite some time, but haven't figured out a good structural attachment for the wings yet. Perhaps your creativity and the folks at Area 52 can solve it.
THend
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Post by THend »

Gary.....

We are working on it. I'd have saved many a good Mako if this was the case.

Not to mention the ability to get the plane airodynamically cleaner...
THend
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Post by THend »

Well, I dashed home from work. I tried to keep my expectations in check because I am no expert at this. Just as I removed the last bolt and nut to hold the thing together for curing Butch called. He was 3 minutes away, and REALLY wanted to be there for the pop.

Well, the one half came off rather easily, the second half required some wedges and REAL careful attention, but it finally released and popped right out. We gave a quick 5 minute sand so it could be handled, and I removed the motor mount tabs on the disk sander.

Here she is, fresh out of the mold, with flash and mold release still in place...
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After cutting a half moon for the engine, it is time to check out the motor installation.
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Another shot of the business end, not looking too bad. [:D]
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Overall, I give this fuse a 75% on looks, but a 100% for combat functionality. There were some minor issues with the wet seam in the tail area, and I can fix the issue by providing some access to that area during the seaming process. The front end came out rather well, but I now know to coat the tab area a little heavier with cabosil and resin. I will apply a small amount of resin to fill the voids...not a big deal in the big picture of things.

My fancy motor mount jig ended up being a tad too large. I measured it, and I guess I didn't set the tolerances right in CAM, so I will re-visit it in software, and re-process the whole shabang, and cut a new one. Otherwise, I'd already have that motor mount complete with T-nuts installed.

Well, enough for tonight.

More to come...
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tmelton
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Post by tmelton »

All your work looks really promising. I sure hope to see the new birds next weekend (Very tall order). I wish I coulda made it over for some of the spitfire work. I just had to work that last mig of mine instead. I am so glad my work is all done now. Best of luck with yours. The first fuse looks great! What a process. I can barely follow all the technical parts of your build with pictures and no beverages. How you guys can make something so cool from nothing but an idea amazes me. The hard parts done now huh?
draftman1
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Post by draftman1 »

Yes you guys have done an awesome job on that spitfire !
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Post by Lou Melancon »

Terry,
This is a really interesting build thread. Well done, keep it coming. I've read about making molds but didn't understand all the steps. Your tutorial is really making it understandable. Can't wait to see the planes and hear how they fly.
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Post by gsjames »

Terry: Regarding popping the fuse from the mold. A guy in the hangar down from me makes all of the wheel pants,spinners, etc., for Van's Aircraft RV-series of experimental aircraft. One of the things that he does to pop the cured parts from the mold is to use an air compressor with the "chip nozzle" to blow high velocity air between the part and the mold. They pop out pretty easily that way and it reduces the possibility of gouging the mold with wedges. Also, after a few parts have been pulled, he is able to eliminate the PVA mold release and just the wax itself is more than sufficient to ensure that the part doesn't stick. Not that I'm suggesting skipping the PVA, because it would suck if a part got stuck, but apparently it can be done with a well-waxed mold. He uses "AeroPoxy" that he buys in 5 gallon cans from Wicks Aircraft Supply Co. (they also have 1 gallon cans, and I think Aircraft Spruce in LA also sells AeroPoxy) He uses a "Sticky Stuff dispenser" to measure out the proper proportions of the components, but that's too expensive unless you are going to go into full production.

The Spit project is awesome!
THend
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Post by THend »

Thanks for the support, and I am glad to share my experiences along the way.

I could install a small connection to the mold and then apply some air pressure to pop it, but it really wasn't that bad. Just the first time for this mold, so I took it easy.

Eliminating the PVA is a possibility too, and a good wax is all that should be needed. However, there is another trick too.... polyester resins and epoxy resins don't like each other, so I could make the fuses of epoxy as well and believe me they will release easily. But, epoxy is more expensive, at least the West Systems is.

I think I'll be buying one of the pump dispencers too, I've seen them in other shops and they are handy.

As for a tutorial, this isn't as good as I'd like. I am kicking around the idea of doing a full blown tutorial, from design in CAD, through the CAM process, machining the plug, making the mold, making the fuse, cutting wings, covering, stuffing ...the whole deal. It would be a big project.

I am currently kicking around what plane to model for this tutorial, at the moment I am thinking of doing the Sky Raider as it is going to be a crossover ship that can be flown in all scale classes, is dirt simple in design, is a widely recognized propeller driven fighter aircraft, and will help all of us recreate the excitement of WWII fighter combat. [:I]

I was thinking about the P40, P51, ME109, Corsair....but I think building the Sky Raider would be best for everyone. [:o)]

Just kicking the idea around at the moment. I generally work in metric, but added English measurements. The wing is close to being legal for SSC, I may need to look at a minor mod to get it up to 400 sq inches.
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draftman1
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Post by draftman1 »

Thats great Terry. A full blown build would be nice. another avenue would be, is to sell the plugs that have been just with the CNC and then we could make our own F.G. fuse. Less time for you. I know doing alot of production work is very time consuming. The skyraider would be cool also. how about the grumon bearcat? for SSC it wouldnt neccesarly have to be a fighter, would it???
THend
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Post by THend »

I am trying to find a way to kill two stones with one bird. Or at least one bird wing. A wing that can be used for two classes would be great ie SSC and Scale, or even Open.

The Spitfire wing meets that requirement and really flies well, the down side is that it takes more time to cut and with the rounded LE is challenging to harden for combat. I will be trying some hardening techniques on the next set of Spit wings.

The SSC ship does not have to be a scale fuse, but I like the idea of being able to use the same wing, and folks (I know) generally prefer to fly a plane that looks like a plane. Maybe a real generic fuse would be cool.

I've been thinking about the concept of getting plugs or molds into folks hands either by loaning them out, selling the plugs, or flat out doing custom work for someone (or a group) who just wants their own mold. Problem is that my disposable time is limited, and you never know if your hard work will do any good. I know locally folks are very interested in what is going on in the shop.

If I could ditch my day job... I'd have much more time on my hands to dedicate to this kind of stuff.

For now, I am trying to stay motivated and moving in a positive direction with RC combat. Half of me is ready to throw in the towel, the other half of me just can't.... so in the mean time I'll do what I can and just play it day by day.

I am truely enjoying this process though, I have learned so much this past 6 months that it is making many of my wildest dreams come true. (Sounds like I voted for Pedro LOL....)

Stay tuned.
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o1moregil
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Post by o1moregil »

Your tha Man Terry!!!!! Im Following this
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(if you can't see the 6 little pictures, right click and "show picture"
THend
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Post by THend »

Can't see the little pics!

What are they, what are they, what are they![:D][:p]
gsjames
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Post by gsjames »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by THend</i>
<br />
I could install a small connection to the mold and then apply some air pressure to pop it, but it really wasn't that bad.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

No, no. You don't need to install a connection, the guy just blew the air in from the edges that he had started to lift out. The air takes the place of wedges. Also, he occasionally used tongue depressors and Popsicle sticks to help release the part.

Cool stuff you are doing.
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