Pic of new Skyray

OK,
Here it is and I have all of you guys to Thank!!!
I am not sure what the finished weight should be, but this one finished out at 32oz with all the hardware on it.
Sounds kind of heavy, but I tried to keep it light.
It has a McCoy .35 RedHead.
Thanks for all the help and to those that sent parts and suggestions.
Now the scary part.... will if fly?

Thanks
Paul

Looks nice, Paul. It should fly fine at that weight. Mine, with polyspan and dope finish and an FP20, flies fine at 31.5 oz. Seems like DirtyDan tested one as heavy as 36oz, if memory serves. I had to repair a spot on the nose after an inverted landing, but I'll try to get a picture soon. Be sure that your elevator throw isn't more than 30 degrees or so. I had too much elevator at first and it was hard to fly smoothly.

Make sure you sand the edges off that prop if you are finger flipping. IMPORTANT.

>Make sure you sand the edges off that prop if you are finger
>flipping. IMPORTANT.

Important on ANY plastic prop (ask me how I know - as I'm typing on KB w/bandaid on my finger).

Paul,

Great looking plane! I have a Skyray .35 kit that I intend to build this winter. I haven't decided what engine I want to use...my choices will be between...Max .20fp, Max 25fp, Fox .35 stunt, McCoy .35 redhead. Did you build your totally plane stock? I have heard it said that it would be a good idea to at least replace the spruce spars with balsa spars (Bigiron in Wichita) for lightness. I will probably do that and will probably use Monokote covering. Let us know the first flight results on yours......T.Durrill

Mr T.
Yes this is all stock. I built it off the plans. I was going to add two landing gears straps but did not have the hard wood to bolt it to. I wish I would have added a block in the nose to bolt to, but then that might have added weight. I land in grass so from what I learned so far I am hard on landing gears. I covered the whole plane in monokote, the main reason was hoping to make it a little stronger on those hard landings, and second to keep it light.

Paul

I have built several Skyray's box stock and one modified for Navy Carrier. They all were light. The lightest was with all monokote finish and small Saito four stroke that is still being debugged. Still trying to find correct prop and still cutting down elevator throw. Have one hole left on horn.

Here's my new Skyray: FP.20, Monokote/Lustrecoat, 28 ounces.
Derek Moran

Hey Derek,

Cool looking airplane. Looks like you blended Flite Streak with Sky Ray.......Wing tips, fin/rudder look Flite Streak and the stabilizer/elevator look Sky Ray.

Good looking combination and at that weight. ought to fly real nice.

Good Job!

Derek, that's a very clean looking ship. Your tank setup is very interesting. Please provide some details, especially the plumbing.

Thanks.

Thanks, guys.
You're right, John, there is some Flite Streak influence. This plane was built from plans (notice I didn't say "from scratch"), so I wasn't constrained by kit wood. I happen to like this tip shape for aesthetic and aerodynamic reasons, so most of my planes seem to get built with them. The fin is stock but the stab is 'Streaked a bit. The nose moment was shortened to help with balance.
Eric, the tank is a 3 ounce Hayes. It's plumbed a bit different than the instructions show, as you noticed. The tank is mounted backwards to provide room to mount the landing gear. There are two taps on the tank: fuel feed and muffler pressure/vent. These are Mac's Products thin wall tuned pipe pressure fittings; the fuel feed is drilled to 3/32 ID. The tank is filled through the tubing at the inboard/rear. While all this looks unusual, it functions the same as any good hard tank. Attached is a picture of my original concept, with uniflow instead of pressure vent.
Derek

Derek,

Very slick. The tank is an interesting layout. Dan will love you.

Thanks for the detail. That tank arrangement is a great idea.

From what source is the tank mount bracket?
Bigiron

Marvin,
That bracket is an MPA special. My CAD program makes designing sheet metal parts pretty easy. It calculates bend allowances and will generate a flat pattern. I contact cement a 1:1 print of the flat pattern to the sheet stock and start drilling, cutting and filing. It can be tedious though- I need a bench-top NC turret punch. . . The material is .064 thick 6061-T6 aluminum.
Derek

Derek,
While I also think the tank mount is really cool, I am also intrigued about the metal backing/motor mount. Could you describe that? Material? Method of construction? Where do you get that material? Thanks,
Nick Vanmatre

Hi Nick,
The engine mounting plate is a "C"-shaped piece of aluminum. Its purpose is to spread the load of engine mounting to a greater area of the engine bearers and to provide engine thrustline offset. Some guys use two strips, one under each engine mounting lug, but I find it easier to make the pad as one piece. This can become an issue with engines, like the Fox .35, that have mounting holes offset from the engine centerline (the left side and the right side are not symmetrical).
Some guys also like to use the mounting plate a sort of universal engine mounting adapter. They screw the engine to the plate(s) then screw the plate(s) to the plane. This will work fine in many applications, but it is not ideal, mechanically. To get the maximum benefit from the plate, it should be bonded to the maple engine bearers (we’re talking high-strength, temperature-resistant epoxy); the engine should be mounted through the plate to a nut plate or blind nuts on the opposite side of the engine bearers- which should also be bonded. I didn’t bond the plate on this plane, anticipating some changes to the thrust offset.
The material you use for the plate isn’t too critical. Any of the high-strength aluminum alloys will work fine: 2024, 6061, 7075. Mine happens to be 5052-H32, cut from a scrap relay rack panel. The material is .090 thick. Some folks use linen phenolic, but it’s not ideal. Forget nylon or any other form of plastic.
Aluminum like we’re talking about is pretty easy to find. K&S has displays in your LHS. I prefer OnlineMetals http://www.onlinemetals.com. One of their 6061 sample packs, 12 x 24, should last you for years.
Derek

Nice looking buch of Skyray 35's.

FYI. The 4 ounce Sullivan RST tank that is shown on the plan works out very well and should not be overlooked. It is very steady on the FP 20 & 25's and doesn't require the use of muffler pressure.

Later

Mike's right of course- a Skyray built to the plans with the recommended hardware flies great.
The changes I made are solutions to my personal functional requirements. I enjoy this aspect of modeling and also enjoy sharing these ideas with the group.
Derek

Great looking examples of the Sig Skyray. I think I will build mine stock and use the O.S. Max .20FP with a Sullivan 4 ounce slant tank. My question is will this tank leave room to bolt on a set of aluminum two wheel landing gear or will I have to use 1/8" wire? ......T.Durrill

Paul, really cool looking plane. I like your colors. Is this the plane you asked all the monocote questions about? It looks like you got it done real good. I cant answer your weight questions, I'm a retread myself. Here's hopeing it flies as good as it looks.

Yes this is the plane that I wore everyone out on. My first monokote job. I learned a lot on this one.
Thanks
Paul

hey Paul,

looks good....if ya need more help with stuff, just holler....there are plenty of people on here that are willing to help....even with things that might seem stupid.

Hey Paul,

Great looking airplane! The Sky Ray is a real good flyer, too. And, Great Engine choice, too. Good luck with first flights.

Another recently hatched Skyray. FP20, hard tank, Brodak dope over polyspan on the wing and silkspan on the fuse. Already minorly repaired after finding the only high spot on a field while inverted.....Hope the high contrast image shows decently on the web.

>Eric, the tank is a 3 ounce Hayes. It's plumbed a bit
>different than the instructions show, as you noticed. The
>tank is mounted backwards to provide room to mount the
>landing gear. There are two taps on the tank: fuel feed
>and muffler pressure/vent. These are Mac's Products thin
>wall tuned pipe pressure fittings; the fuel feed is drilled
>to 3/32 ID. The tank is filled through the tubing at the
>inboard/rear. While all this looks unusual, it functions
>the same as any good hard tank. Attached is a picture of my
>original concept, with uniflow instead of pressure vent.
>Derek

Derek,
Are the pressure fittings held in place by tapping threads into the wall of the plastic tank (and possibly the white plastic "washer") between the fitting and the tank? Is there glue involved? If so, what type? Any tips for leak prevention?

Thanks,
Kim Mortimore
Alameda Aer-O-Nuts

Kim,
Good question- it's the crux of the whole scheme. See the attached sketch. I used two silicone gaskets to provide the seal. No goops.
I tested the tank to 30 psi, which is at least 10 times the service pressure. This is not the best solution because the OD, or low pressure side, of the gaskets are not constrained. It would have been necessary to machine a recessed seat on both faces of the nylon nut (kinda like an o-ring groove, only flat) to accomplish this- something I couldn't do with the tools on hand.
The gasket material does not have to be silicone. It could be Buna-N, Viton, or whatever. The Shore hardness could be anywhere between 50 and 70 (A-scale). Thickness could be .015 to .031. Materials like this are available from McMaster-Carr.
Derek

Thanks, Derek! Answers don't get any better than this!!

Kim Mortimore
Alameda Aer-O-Nuts

Great looking examples of the Sig Skyray. I think I will build mine stock and use the O.S. Max .20FP with a Sullivan 4 ounce slant tank. My question is will this tank leave room to bolt on a set of aluminum two wheel landing gear or will I have to use 1/8" wire? ......T.Durrill

Derek, Is that Solidworks your using for the CAD stuff? Kind of looks like it to me.

Yup- it's SolidWorks.

>
> Great looking examples of the Sig Skyray. I think I will
>build mine stock and use the O.S. Max .20FP with a Sullivan
>4 ounce slant tank. My question is will this tank leave room
>to bolt on a set of aluminum two wheel landing gear or will
>I have to use 1/8" wire? ......T.Durrill

It gets a little crowded in there, allright. I use thin shims of a stiff sheet foam material from a craft store to space the tank up and clear the gear. Since the motor is on phenolic plates, the height issue is about a wash. I found that it can give you a reason to tip the tank end outboard a little to help pick up the last drop of fuel.
Kelvin

I know gear plates can be install. Mr. Buck did it on his. I was going to do it on mine but did not think it would hold up because I fly over grass. There was not any hard wood other then the doublers to mount to. I am very bad at landing and the plane seems to hit the gear and bounce. I would add a little hard wood to bolt to if I had it to do over.
Good luck.

Paul

There was not any hard wood
>other then the doublers to mount to. I am very bad at
>landing and the plane seems to hit the gear and bounce. I
>would add a little hard wood to bolt to if I had it to do
>over.

Some dowel stock inserted through drilled holes works well for supporting the LG bolts. Plus the aluminum gear spreads the load around more, anyway. I find that fairly stiff gear lands easier than springy piano wire. The wire gives that "SPROING" effect.

T.Durrill,

Don't forget, it helps--a lot, in my case--if rear of tank is jacked outboard 1/8" or so, just to get all the fuel picked up, to get better cut-offs at end of flight.

This and careful location of sheet aluminum gear will work just fine. Incidentally, my Skyray 20 is using single-strut landing gear and suffers little for it.

Thanks for the tips Dan,

I might go with a single wheel on my Skyray if it works that well. Good idea to move the rear of the tank out to improve fuel flow.....I will incorporate that idea as well.