insane multi-engine
 

Gotta question for alla youse multi-engine gurus out there; do you suppose 12 Wasps would power an 80" span, 1400 sq. in. seaplane?

RE: insane multi-engine
 

Just so ya know I ain't TOTALLY off'n my rocker, here's what I have in mind. I've wanted to build one of these ever since I saw a picture of one in my youth.

RE: insane multi-engine
 

That raises a good question. How much thrust does a Wasp produce with, say, a Cox 6x3? Even though 12 Wasps is less than a .75 in terms of displacement, you'd be getting a lot more thrust. Maybe 12lbs or more, who knows?

RE: insane multi-engine
 

Unless you had them all feeding of of one large fuel bladder the first engine would be out of fuel before you got the last one started. I think I would try to designing it such that it had 6 functional engines and the rear pushers would be free spinning just for scale looks. I have an 18 oz plane 30 in span trainer style plane that flys very well (not as slow as a trainer w/a Cox 6x3) with an AP Wasp .061 so think about scaling acordingly and using one 3oz tank for every two .061's or there abouts.

RE: insane multi-engine
 

I figured to have each pair of engines running off a common tank, where the nacelles would basically be just tanks with an engine on each end. I hope to achieve something close to 2 oz per engine. That oughtta give me enough reserve to get 'em all going if they're cooperative.

RE: insane multi-engine
 

They may have trouble sucking the fuel from a 2 oz tank. You'd want to try it first.

But I doubt you'll have any trouble at all with the power. I'd shoot for keeping the weight down a little. Say 7'ish lbs tops. First of all it would give those Wasps a fighting chance and second it'll make the airplane fly slower. The original was apparently a very slow flying airplane.

Even at 7 lbs and if you only ran 6 engines. That's only just over one pound per engine. And I doubt if a Wasp would have any trouble flying a one pound airplane.

RE: insane multi-engine
 

You're not crazy. There was a Spruce Goose with 8 .010s. Some of the guys in the group here have seen it.

I think you'd have more than enough power. I use 2oz tanks on most of my Norvel .061s.

I've seen plane started that had eight OS .46s. It took 3 guys; one on the TX, one on the glow ignitor, and one with the electric starter. The procedure was start an engine, set the needle, shut it off, start the next, set the needle... until they had been through all of the engines. Then they went back to the first one, started it, then the second etc.

RE: insane multi-engine
 

I got 13,800 on a MAS running 15 nitro. That is 20.64 oz of static thrust on the thrust calculator. So that would be 15.5 lbs. of thrust with 12 of them. Should have close to vertical performance with that!

RE: insane multi-engine
 

Yeah, that would be almost like putting a.70 in a 7 lb plane, but with more thrust, shouldnt be a problem,probably be too much of a pita to be any fun...one of those planes built just to see if it can fly...better go with 4 oz tanks..Rog

RE: insane multi-engine
 

15.5 lbs. of thrust, eh? I've got a Great Planes 1/4 scale Cub (90" span) that turned out to be a lead sled. Flying weight 13+ lbs....flew well with a .61 2-stroke. Sounds like I could scale this thing to fit the props and have everything work out OK. Excess power would be a good thing. I'd say there's a fair-to-middling chance it'd lose more than one engine per flight.

I've used both 2oz and 4oz tanks with reedies...I don't imagine the draw on a Wasp would be much - if any - worse.

Hmm...one problem with having someone go down the line with the ignitor is the push/pull arrangement and the fact that the nacelles are so close together. Be mighty dangerous to do that. Perhaps some sort of wiring harness built in would be a better idea, maybe with a switch or similar to light up only the engine being started.

RE: insane multi-engine
 

That plane was done in the 70's and featured in the old American Aircraft Modeler magazine. It had 12 Cox motors and the caption was that they woundered how they got all 12 running. Amazing how memory remembers this stuff and yet I can't remember where I put the car keys.
Dennis

RE: insane multi-engine
 

I wonder if you could run them all off of one tank using a Perry pump or something? If you made a harness for all the glow plugs starting it with a Sullivan started might go pretty quickly. I don't relish the idea of hooking up all the throttles and setting the idles though[X(]

RE: insane multi-engine
 

Did the original Have 12 engines or 6?

RE: insane multi-engine
 

A 12 engined 1/2 A model? This project will be like hitting yourself on the head with a hammer.....it will feel good when it stops! You got part of it right - insane. After building multi's for years (including one with 2 x Medallion 049's & 2 Medallion 09's) god took mercy on me & on the eighth day gave me electric power! Still, it's your head! - John.

RE: insane multi-engine
 

I attended the 1967 nats as a kid. One of the demonstrations was a large u-control model with 13 Cox Babe Bee engines mounted on the wings leading edge! The crew would call for volenteers, small kids of course and give them an engine to start. When enough engines were running they would wave the kids away and fly the monster! The sound of 10 to 13 Cox engines, running at the same time, and not in sync, is something you never forget! Good luck with your project!

RE: insane multi-engine
 

As for throttling the Wasps, I had this idea: Take a long piece of music wire and wrap and solder "L" shaped pieces of wire onto it with the same spacing as the engines. What you have is like an aileron torque rod with six posts sticking up off of it. These posts connect to the throttle arms on the engines. The end of the long wire is bent at 90 degrees just like an aileron torque rod and connects to the throttle servo.

So, one throttle servo controls all the carbs together off of this single, long torque rod. It could be run through the wing. Picture the way an aileron torque rod actuates an aileron, but, instead of the wire inserted into the LE of the aileron, you have six extensions coming off the rod connected to the carbs.

RE: insane multi-engine
 

Here's another Kicker.... 1/2 the engines are pushing.

RE: insane multi-engine
 

Then the torque rod system is ever better. The rod in the other wing which is driven by the same servo operates the pusher throttles (the same way the two ailerons operate in opposite directions). You just have to use two throttle servos each with their own pairs of opposite moving torque rods. I've seen much more complicated setups with tri-gear mechanical retracts.

One servo operates the tractors in one wing and the pushers in the other wing. The second servo does the opposite.

Since the engines are back-to-back their throttle arms are on opposite sides and the pushrods from the torque rods won't get in the way of each other; they're staggered down the wing.

RE: insane multi-engine
 

Save time, use the hammer now. Maybe the desire to build this thing will go away when the headache does.:D If not, be sure to put all blunt instruments under lock and key!

RE: insane multi-engine
 

And how long did it take Mr. Hughes to get his Goose built

RE: insane multi-engine
 

If the hammer trick won't work think
about the need to only control about
four of those powerhouses.

RE: insane multi-engine
 

Considering the layout of the engines, your idea really makes a lot of sense.

RE: insane multi-engine
 

That's pretty much the solution I came up with. Working the carbs isn't the trick, figuring out how to get fuel to 'em IS.

RE: insane multi-engine
 

I would think that 6, 4 oz tanks would do the trick with each pair running off of a T connector.

RE: insane multi-engine
 

If I were doing this I would build the engine mount/fuel system/throttle torque rod/servos system as one big working assembly and test it until it worked perfectly. Then I would build the wing around it. The system could be built as a rigid sub-structure comprising two or more spruce rails. These rails would then become the main spars of the wing to which the ribs would be glued. Lastly, you would add the LE, TE and wing tips. I can visualize it in my head easier than I can describe it.