Speeddelta with OSMAX 91VRDF and pulsejet
 

http://images.rcuniverse.com/gallery.../lg-250454.jpg

Hello,
just started building a speeddelta with an OS MAX 91vrdf and a pulsejet, i'm try to prove that's possible and not to
set a speedrecord.

Does anyone has experience with this combination in the past?
thanks

Is it April 1st already?

A couple of turbines would top things off IMO.

If you are trying to prove it is possible, if somebody has experience with it then they already did it first and you are too late..

Well, there goes the only sane reason to do it. I wonder if the propwash from the .91 would be enough to get the PJ started...

Oops, didn't mean to ruin everything with a logical conundrum. If nobody chimes in, then he is the first and will lead others to follow.

It ought to sound pretty wild, assuming you can hear the .91 over the PJ (not sure about that one!).

I wonder what those little flat surfaces ahead of the wing are for?

I'll pass on hand launching that one!

Dave

It won't even fit on a conventional sledge launcher. The launcher will be a project in itself.

Using the cyl. head and pipe as landing skids might need some rethinking as well. First time you get a lean run on the .91, you're screwed, because you won't be able to tell.

LOL...!

Nosferatu.......How much fuel for each engine do you plan on using...?

That combo would suck right about 1 pound per minute combined --> 5-6 oz/min for the .91 plus ~340cc/minute for the PJ = about 54 fl oz for 3 minutes flight time = about 3lb.

That puts the takeoff weight at 8 lbs. or so. We're gonna need a bigger bungee!

Well he can use outboard wing panel extensions for the take off. Once safely up to flying speed wing panel extensions [that are "slip fit" to the plane's main structure are jettisoned, leaving just a 500 square inch delta for the remainder of the flight.
See how simple this stuff is...?
I don't know anything about Pulse Jets, but hopefully he can have it "auto-start" once the plane is up to speed.
The added push of the jet should allow the .91 to fully unload a massively oversquare prop too.
OK, what else needs to be figured out....oh yeah, the launch.
No problemo, just start the engine and launch it from the back of a moving pick up truck at about 25 mph.
Jeeze, I can't believe I have to be The Visionary who does all you guy's thinking for you...!

I haven't progressed past an expression something like this:

http://ia.media-imdb.com/images/M/MV...14,317_AL_.jpg

BUT - I sure hope it flies, it will be hilarious. The .91 probably represents what, about 30% of the total hp on tap? (based crudely and irresponsibly on 5 oz/m for the .91 and 12 oz/m for the PJ). Yeah if it is pitched high and works in harmony with the PJ.. far out!

Well, it looks like really nice work has been done so far on it..!

I keep saying I'd like to have the OS .91 DF on a delta someday. .50 is the largest 2 stroke I've ever run on a plane so far.

will it have to be registered?

Folks that run these things keep telling me to keep the OS to about 20k for longetivity, so when I run mine guess I'll do that. But it's still going to hump out some useful hp at that speed I'm sure.

I have a 40" Demon about 90% drafted out. If I insert OS .91 VR-DF dimensions for the front, and a Tettra/Jett 11.5-14oz behind, and replace rib 3 with ribs 3 and 4 at 4.2" centers and bla bla, that's aboot it. I worked on this a while ago.. aha, drawing says I created it March 2010. :rolleyes:

Center rib is 1.7" deep, same airfoil. 781 squares. Hmm, maybe 38" span..? Nah, big is ok.

Whatever size the "Laser Delta" or "Laser Aero" [or whatever that thing was called] it looked pretty good in a video I saw posted.
Build a generous sized delta "modular" with 3 inch wide rib spacing near the tips and bring a hacksaw and some packing tape along if the first flights are too boring.

It couldn't hurt to look at what the .45 sized wing loading is with the 32 inchers and go from there.

8 or 9 years ago, I bought a Laser Arrow delta ARF from Valley View RC. Flew it with an OS 32F, piped. 36" span, IIRC, and quite thick. 3 or 4 other guys at the field got one too. They used everything from .40's to .61's and they were all about the same speed. Compared to the Demon, they were built like a tank. All of the internal structure was lite-ply, and there was lots of it. Rib spacing was about 4". One nice feature was a small rounded ventral fin on the CG that doubled as launching handle and landing skid. Everything except the engine was buried within the wing. The covering was crap and mine had a pretty bad case of oil-soaking when I retired it. By then, Tom at Valley View RC couldn't get them anymore, so that was that. Not a bad airplane, but not a candidate for truly high speeds, either.

It had to be a combination of the weight and thickness that made them slow.
Way before the Diamond Dust came out I scratch built a triangle shaped monstrosity [after studying a 2" x 2" photo of a Holy Smoke] and what a disappointment that was. It was extra embarrassing since the local club had such high expectations. Mine was built like a tank with numerous ribs and spars, lots of sheeting.
One of the "Barney Fifes" thought it was going to be too fast for the human eye to keep up with and he wanted to create a network of spotters to relay information back to me to assist navigation....not only was it slow but it would fall out of the sky during a slow turn. These were the days when you never knew what you would see being tried on for size at the club field.!
What sounds about right [for a .91] is the 36 inch span. Build it like a Demon though.
The Laser Arrow feature I like is how the fins are used as fairings for the elevon pushrods.

My Laser Arrow's elevon servos were mounted under hatches, but no external fairings were present. At the time, it never even occurred to me that fairings would be a plus. Kind of like a Shrike, it was too thick to inspire much thought of refinement.

Yeah, 40" is a big kite. Might be perfect for some. I''ll work out basic specs of 36 and 38 inch and post.

I have been staring at fin roots and elevon pushrods for a while. Nice way to do it. A hatch underneath would provide the needed access I think.

Where I saw the fin / fairings was in a batch of random photos while doing a Laser Arrow Google search..so it could have been a different model.

Think of an easy to fly plane that does 180 mph all day with $2 props, runs on straight methanol and only consumes 1 glow plug every 20 runs.

Demon + FIRE Jett .50LX + cowl. Oh yeah, it needs oil.. better use an HK pulsejet with a bladder then.