PylonWorld

The 3M77 held the first plug down great, so I did the other side that had the paper template attached. I did the mold release treatment and left it overnight.

This morning, the plug with the paper template attached was loose, except in the tail area. I noticed that the 3M77 was wet and gummy. I then realized that the FreeKote 700 mold release is a glue solvent of extreme proportions. I squirted a little under the tail area, and it came loose.

The paper template on the right side was acting like a wick and allowing the FreeKote to go all the way through. It is the best tape gum and contact cement remover I have ever found. Even better than acetone.

Some soaked into the plywood on the paper template side, so I may never get it stuck down. Most of the time, you bolt a backing board on. But with a molded in rudder, that is hard to do, and keep the fin down. I may have to use a combination of glue and bolting.

Definitely a hard lesson learned.

PylonWorld

I've started making the Hughes molds.

I use a mixture of epoxy, cabosil, and graphite for the "gelcoat" layer. I have consistantly had a hard time getting the mixture fully mixed so that there are no lumps of cabosil.

No different on the Hughes molds ... one side looked like a mountain range.

Tonight I was mixing up some epoxy and cabosil, and at a certain point, the cabosil went from lumpy to nice and smooth. But it was much thicker than the way I use it as gelcoat.

A couple of days ago, my next door neighbor's pool filter literally blew a drain plug out because the filter was so clogged. This evening he was telling me about how another neighbor premixes some powder that you dump into the system with water, so that it doesn't clump in the filter.

This information helped me to realize the solution to my problem. Mix up the epoxy, part out half of it, mix the full amount of cabosil in half, and mix the graphite in the other half. The cabosil mixture got real stiff, but I added it gradually, and got it smooth. Then I combined the pigmented half with the gooey half, and mixed. Finally ... smooth gelcoat. So I put some on the rough side, and I now have hope of actually getting the cloth down.

I did the initial cloth layers on the other half using the aforementioned stiff mix, but it's always easier to get cloth to lay down on a solid and smooth surface, that a rough surface with mushy stuff between the peaks.

More lessons learned.

PylonWorld

Here is the left side of the mold on the bottom. The right side plug is on top and you can see the roughness of the gelcoat layer.

Removal of the mold was not too hard. However, the plug had a gap between it and the plate, and the epoxy naturally found its way into the gap. I thought that I could fill the gap with wax, but I should have used some clay. This resulted in some chipping on the edges in certain places. And there is one big chip behind the canopy that I will have to fix. I'll show a close up of the chip and how it is repaired later.

Now I need to lay up the right side.

Arch Adamisin

Don, like I said before, that H-1 looks great. I can't wait to see it finished. It will be a real attention grabber. Have you decided how you are going to mount the motor, upright or on the side? Only about two weeks until test flight?

PylonWorld

Thanks Arch ...

We've finally gotten some dry weather here, so almost all of my time is going into the field, R/C car dirt track, and my yard at the moment.

I'm going to try to get the other half of the mold made over the next week, and do any molds repairs that are needed then.

I made a reference Swee' Pea wing out of cloth, mat, and CF. It'll be good to have so that I don't have to worry about dinging up a real wing, plus we're going to use it for making a jig to mount the Swee' Pea tails.

I believe the engine can be rotated down to a 30-45 degree angle and tuck the muffler under the centerline. But, since the cowl is small enough, a piece of glass can be used to restore the cut-out for the engine. This may lend itself to a decent looking upright to semi upright mounting.

Since this is a prototype, and I can't join the fuselage before the wing saddle is cut out, I've thought about making it available for the viewers of this thread really cheap ($30?). Some may even get freebies. So if anyone would be interested in receiving one, email me with your email address and mailing address.

PylonWorld

I patched the chip on the left side mold, and got the molds sanded, compounded, and polished this week.

My goal with this project was to create a plug using pink foam that would produce a mold for a production or near production quality prototype fuselage. And to produce some parts to see how they look.

To me, this first half looks great. I didn't have the epoxy/cabosil mixture thick enough and it migrated down, leaving a couple of voids at the back of the radial cowl, but that was just a lay up problem. The plane lays up easily, and the lack of a saddle makes that area MUCH easier.

But any wing and stab can be fitted to this fuselage.

I was going to wait until I built and flew one before submitting it to the Q-40 approval committee, but I'm going to draw it up, and go for approval. Whether or not it will be competitive with the big snout I don't know. But I do know that I can produce a fuselage in a little over an hour, and that's cool. [8D]

As I mentioned above, if you have been following this thread and would like to receive one for free or a nominal fee, email me. (US only unless you want to pay shipping)

BasinBum

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There is a movie being made called The Aviator about Howard Hughes. They are building a 16 ft. span flying model for the movie. They were scheduled to use the full scale plane untill the accident so now they are going to try to use the model.

rsieminski

Outstanding thread!
I have a few questions if you have the time:
How will you mount the wings and stab? How many layers of what weight cloth will be used for the finished fuse? How thick are the molds? I'd love to do this same thing. Ive made landing gear and other sm projects.
Thanks,
--Rick

PylonWorld

Thank you.

The stab saddle will just be cut out and the stab epoxied in. Then fillets of epoxy and some filler material will be put around the stab.

The wing saddle will be made of 3/16" to 1/4" balsa epoxied to the sides. There will be a 1/32" plywood doubler on the inside of the balsa. Then 1/4" wing hold down blocks will be added, and 1/16"-3/32" dowels will be used to pin the hold down blocks in place, Quickie style.

Right now I'm making fuselages with one layer of 2 oz cloth, one layer of 6 oz, and a 6 oz doubler in the wing saddle to nose area. (the diagonal line you see). I'm actually going to change the recipe a little to work on getting the weight as low as possible and not create a strength problem.

The molds were made with a thick layer of pigmented and thickened finishing epoxy. Then 1 layer of 2 oz and 1 layer of 6 oz. Then 2 layers of 6 oz, and 3 layers of 6 oz. They are about 1/8" thick, and not really thick enough for hard core production, but fine for a prototype.

rsieminski

So the wing saddle will be cut out also, to accept a 1 piece wing? Right?
With just 8 oz of cloth is it stiff enough? Will it need formers? I was thinking of using 1/4" cf cloth bands as formers.
What is the weight of the 2 fuse halves?
I use epoxy now, but what about vinyl ester resin. The guys at the shop claim it's more dimensionally stable and hard/strong like epoxy. They suggested my molds be made of epoxy and parts be made of vinyl ester.

Really looks great!
Thanks for the info!
--Rick

PylonWorld

Yes, the wing saddle will be cut out. I have the wing molds for Jerry Small's Swee' Pea (that were done by Norm Johnson), and to start with that is the wing that will be used.

I didn't put a wing saddle in for two reasons: 1) I can move the wing to change the moments to fine tune the performance, 2) I can use any wing on it. Since the Swee' Pea wing is a 52" span with a 10" chord and 5.5"-6" wing tips, I wanted to be able to create a 56" span wing if the 52" wing slows down in the turns too much. Adding a saddle is a little extra work, but nowhere near as much as carving a new plug, or trying to move the wing around or change the wing with a saddle in place. When I've decided on the wing location and type, I'll lay up some thicker parts to use as male molds, and will add the saddles and make new molds.

There is a possibility that I will actually build some as one piece planes. Harder to transport, but the trim doesn't change from one wing mounting to the next. I may even try plug in wing panels.

the 2 oz plus 6 oz is plenty for the rear. Because of the curviness it actually is quite rigid torsionally. I have used 12K and 50K CF tow as stringers and formers with good results. The 50K takes a lot of resin to wet out though. The front has an aditional piece of 6 oz, so there is 14 oz from the rear of the saddle to the cowl ring. CF 6oz could be used up front for a steel rigid front end. However, CF dust is very dangerous, and since some grinding will have to be done on the wing saddle, I won't be making any for myself that way.

I know of one Q-40 manufacturer that uses 2 layers of 4 oz and a 4 oz doubler. I don't like this because it results in pinholes. I'm going to try 1.4 oz for the first layer, because it conforms to curves better than the 2 oz that I'm using, and should reduce pinholes even more.

Stay with epoxy for the parts for several reasons:

* The pot life of polyester vinyl resin is the same as the working time. If is goes off in the pot in 15 minutes, you may have 16-17 minutes of working time. With laminating quality epoxy, you can mix small batches, and as you need more resin, you mix more batches. The thin film set time for epoxy is usually 2-6 times the pot life. So a lay up is much more relaxed. I've laid up between 1000 and 2000 fuselages, wheel pants, cheek cowls, and other parts with polyester, and the epoxy lay ups are easier. The viscosity of the epoxy resin is important. West System 105/205 is too thick for laying up model parts. 206 hardener is much thinner and lays up far easier, plus it has a 20 minute pot life.

* Polyester shatters in the thicknesses we use on model parts. Polyester never really finishes curing. It gets more brittle with time. If you look at some well used planes with polyester fuselages you will see cracks.

* Epoxy does not bond to polyester. When installing firewalls, servo trays, etc, you have to scuff the polyester down to the fibers to get a good bond. Scuffing epoxy is also wise, but epoxy will stick to epoxy.

* I don't like using polyester on carbon fiber. It can be done, however, I don't like it. I don't feel that the poly penetrates the CF fibers as well.

I can't give you the weight, as I've given away the parts that have been produced so far. I think it was 4 ounces or less for the half.


Hey Ed, can you weigh that half of the Hughes H-1 I sent you and post the weight and some comments.

PylonWorld

I forgot to address the stability issue. West System epoxy does have a relatively low heat deflection temperature. It is around 120 degrees depending on the hardener used. Aerospace grade epoxies are available that are up around 250 without a post-cure (baking) and 300+ with post-cure. To post-cure, you need to make the molds from high temp materials.

You may have seen some articles about straightening composite wings by using a heat gun. This is possible because of the low heat deflection temperature of the epoxy used by most of the racing plane manufacturers.

Don't leave composite airplanes in hot cars.

PylonWorld

Rick,

If you would like a set of male molds for the Hughes, so you can get started with making bigger stuff without having to carve a plug, I'll make you a set of male molds for the cost of materials and shipping. Email me if you are interested in either the male molds or just a fuselage.

PylonWorld

I haven't posted anything about the Hughes lately because I've been so busy with the RCPRO software. But I did finally make a complete and usable fuselage. You can see it here alongside a Dago Red and a Swee' Pea.

PylonWorld

Here's a head on of the Hughes and the Dago Red.

Objects near the camera are smaller than they appear. ( The snout of the Hughes )

PylonWorld

Here are side views of the Hughes, the Swee' Pea, and the latest Dago Red.

PylonWorld

Here is a better shot of Lyle Larson's Dago Red with the fin and belly pan on it.

daven

My Feedback: (1)

Is that the older "longer" nosed Dago, or newer "shorter" nosed Dago?

The Hughes looks good, but its kinda big.

PylonWorld

It's the Dago Red version from summer 2002 with the 7.375" cowl ring to leading edge. The long nosed versions were over 8".

The Swee' Pea in the photo is 8.625", but it has a relatively straight leading edge, so it's MAC is a little further forward than it looks, but the short nose Dago MAC is at least 1" ahead of the Pea.

I know the cowl on the Hughes may be a problem. The Hughes was a "for fun" project and a trial run for the pink foam plug technique. Now I actually want to build one and see how it does. Even though the Hughes looks big, it is just over 5" tall and the cross section is only about 0.25 to 0.5 over the minimum 12.5 sq inch cross section requirement.

The Swee' Pea wing is only 52.5" in span. So the Hughes with that wing will be pretty small. The Swee' Pea wing has (almost) the same airfoil as the Sidewinder.

Any way about it, the plane won't be my limitation ... my skills will be my limitation.

One other thing. The Hughes would benefit from a bigger prop. I wish I could use a Q-500 engine and APC gray props. A project is underway to explore electric power for Q-40's ... the Hughes might do well with a big prop, like a 14x14, on a planetary geared brushless motor.

PylonWorld

One point about the snout.

If you look at the pattern of airflow behind a propellor around the nose, you will see that all of the air bumps into the engine. That's why real Formula 1 planes have the cheek cowls on them. The engine sticking out and the open area on the typical Q-40 is a big drag on the newly generated thrust.

Dan Kane's Pole Cat and Big Bruce's El Bandito have the infamous access hole cover. I made the diameter of the Hughes cowl such that the required amount of cylinder is sticking out. But just barely. Fortunately I measured a Nelson before I started as it is 1/16" shorter than my JETT's. I plan to use an access hole cover. This will leave less disturbance to the airflow off of the prop. The spinner is a 1.5". Not a lot of real usable thrust is generated by the inner 1/3 of a prop.

I actually think that the big drag area will be the back of the cowl ring. But I shaped the cowl to try to minimize drag there.

MarkF

Don, I am very interested in this plane for an electric conversion.Some of us down here in so. Cal have been toying with the idea of an electric plane with wheels that goes really fast.I think I could come up with a motor combo and 12 to 14 cells that could push one of these planes to 140 or maybe 150 mph.We have discused going to 20 cells and possibly doing 200 mph but thats a little ways down the road.
My friend Troy has one of Dan Kanes airplanes he was going to convert but who knows when that will be. I would sure like to make a go of this if you could lay one of your airplanes up with electrics in mind.Please let me know what you think.

Mark F

johnnfs

hi. would you be interested in selling a hughs h1 with the tail and wings on. im not wanting to race it,just want to put an os .46 on it for sport flying.
thanks in advanced,
john

pylonracer2

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Would like to see how the plane is doing and if it has gotton closer to completion. Also are you looking to sell these planes after you test fly this one?

pylonracer2

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I would like to buy one, let me know what the wait time is and how much it would cost to ship to south florida.

Thanks
Charlie

js3

My Feedback: (3)

Charlie,

If you go to the RCPRO forums and ask your questions there, you'd probably get a better response. I won't go into the details.

Try this link: [link=http://www.rcpro.org/net/Forums.aspx]http://www.rcpro.org/net/Forums.aspx[/link]