Talking Twins

[wwwarbird]

 I'm researching for the upcoming building season here, please bear with me.
 When running a twin engine control liner, on separate fuel tanks, which is the desired engine to quit first during flight, inboard our outboard? Does it really matter? I would assume that (ideally) you would want to have the outboard quit first, because then wouldn't the plane want to yaw to the outside with only the inboard engine running?
 I've built and flown a couple .15 powered twins in the past that didn't seem to make any real difference which one quit first, but, they were also twin tail designs with differently offset rudders inboard and outboard too. Also, I never really flew them in any real windy conditions either.
 I'm planning to build an original design, semi scale warbird twin starting this fall, with about a 65" span and a pair of 4-stroke .30's and a single vertical fin, so I'm just doing some homework. Any input here will be appreciated.

Thanks!

[minnesotamodeler]

You want the outboard to quit first, so drag on the dead engine helps line tension. But a well-designed twin should fly (and stay out) on either engine.

--Ray

[Willis Swindell]

My Heinkel 219 Owl with two Saito 30's 650 sq in wing 64 oz.
Willis 
How about a push pull with a fox 19 in the rear a Tigre 35 in the front or a Owl and a Foker 23 on a Brodak war bird wing platform.

[minnesotamodeler]

Very cool...you use pusher props or reverse cranks for the pushme/pullyou?

--Ray

P.S. Mine was 40 years ago!

[frank carlisle]

Willis,
I see you got the jump on us as far as twins go. Those are very cool models.
Thanks for posting the pictures.

[Willis Swindell]

wwwarbird I think you would be happier with larger engines for the size plane you are talking about  My 30’s will fly my Heinkel fine in calm air but no drive in the wind. But saying that the three contest I have flown the Heinkel in, the wind was probably 15 to 20 mph and my scores were higher then what I usually fly. The wow factor I guess.
I used pusher props on the push pull.
Willis
PS
You have the right Idea about the single vertical fin twin rudders are just waiting to be knocked off.

[wwwarbird]

 Great stuff Willis, I REALLY like the 219! What is the wingspan on it? I'm not divulging what the subject of my model will be yet, but I'm pretty sure it hasn't been done as a stunter, it is WWII era as a clue though.
 Good point on the model still being flyable on only one engine, my previous two twins actually flew fine on one engine up to 45 degrees or so. My only concern here is just that short time between when one engine dies first, and then the second before landing.

[Ironbomb]

I think the shape of the wing of a Mosquito would lend itself well to a stunter.

How close am I? 

cant wait to see what you are plotting 

Greg

[wwwarbird]

That's already been done, but not by me, and yes, it works well. Too obvious and too easy though.

[Ironbomb]

oh, I didnt know it had been done. I would like to build one, I always liked the Mosquito. Maybe after I build my P-38, want to put two 45s on it, 

I will stop guessing, and wait till you come out with it 

so get it built 

happy building

G 

[Willis Swindell]

Picking out the plane is the most fun, I looked for almost a year before I picked the 219 and longer then that for the Fokker 23.

[Willis Swindell]

I found an Idea in a old magazine for cutting twins off at the same time. Put a tee in the fuel line at the needle valve seat on each engine then run a peace of fuel line between the engines Pinch off the line until you get both engines running then un pinch the line. When one engine quits the other will suck air and cut off. I haven't tried it as of now but sounds possible.
Willis

[Leester]

Greg: RSM just came out with the MOSQUITO several months ago. Check it out on RSM's web site. Very Kewl. www.rsmdistribution.com

[Bob Zambelli]

A 4-stroke twin is a great idea! I was first inspired when I saw Willis fly his at the Brodak Fly-In. Two SAITO .30s as I recall.

Since I had a plane called “The Plane” that was designed just for testing and evaluating different engines, I decided to convert it to a twin. I epoxied two small profile fuselages on the wing, about 10 inches out from the main fuselage. I then put two OS Surpass .26s in and flew it. It did well but something was missing. Since the original fuselage was still intact and begging for an engine, I put in a third – an OS .20 4-stroke.

You cannot believe how well the plane flies. The sound is totally unique and the performance quite reasonable. I plan to enter it in profile stunt someday.

Sometime in the future, I plan to create a semi-scale fun stunt plane with three engines. Believe it or not, there was actually an experimental Piper Cherokee with three 150 horsepower Lycoming engines.

Bob Z.

[Leester]

How much weight did you need to balance that plane?

[Bob Zambelli]

I machined a tailwheel from copper (specific gravity is 79% of lead) and it's still noseheavy. I'll probably extend the tail by around 2 inches.

Still lots of fun to fly.

Bob Z.

[wwwarbird]

Bob, you should do a semi-scale Ford or Junkers tri-motor!
About the Mosquito mentioned earlier, Jack Sheeks did one and I think the plans are available through FM or someone. I think the RSM kit may even be based on that design. 

[gerry boyd]

I have built several twins and have always used two tanks allow the outer engine to run for a short period before starting the inner that way the outer always stops first    . However I do start each engine to warm them up and set the needle valve if they need adjusting. I built two Martin 167 bombers with Cox TD .049 engines and they fly very well they are semi scale but are full bodied and the engine pods are also built up and the engines are cowled. They fly well on 40 to 45 ft. lines and will do loops , eights , inverted and a great square loop. I do my own construction plans. I recently finished and flown My Martin Mercator wich came out near the end of the war. It has a 53" span and is also full body and engine pods with two O.S. 15s and fly's very well. Oh with regard to weight the first twin .049 had to have 1 1/2 oz. of lead in the nose to balance right. The second one needed only a 1/2 oz. as I built the nose an inch longer. The Mercator didn't need and weight. Good luck.

[wwwarbird]

Gerry, got any photos of the Martins?

[Robertc]

I have built several twins, the last two with retracts.  The attached picture shows my first Sheek's Mosquito.  This plane was lost when the inboard engine quit in the four leaf clover.
Just never could get the line tension back.
I have always TRIED to get the outboard engine to quit first, but with the one exception
in the four leaf, I've never had any other problems with the inboard quitting first.

On my current twin, the first flight while inverted, the inboard engine threw the prop and kept running in a 25,000rpm 4 cycle.   Plane flew fine on the outboard engine.  I gave thought to trying to get it upright as it was flying so well, but being on grass, thought it best to stay
inverted.

[Elwyn Aud]

When Tom Tomoser came down to fly in our Triathlon/Mirror Meet in early July, he brought along a few planes he had built in the early to mid 50's. One of them was a twin. It's kinda on the opposite end of the spectrum from an L A Heat or Sheeks Mosquito. The airfoil was a lot thinner than a Ringmaster. How bout that funky canopy and strange squared off nose with smaller nose cap. It's neat seeing something old and different.  I think the engines were early Fox 19's.

[charlie]

 I was interested for a long time in experimenting with building a stunt model controlled by a single wire, using the Stanzel `Monoline' system where the controls are driven by the wire being twisted by a special handle.  Normal control line is `U' control using two wires and pulling on one or the other to operate either the up or down control functions.  U control relies on line tension so that it can function, but one of the features of monoline is that it will work without line tension.

The idea of monoline stunt was universally denounced by most of the modellers that heard about it, as being an indication that I was of unsound mind.  In fact Fred Adler, when he saw the finished product, finally produced in mid 1997 said "I used to think that you were eccentric.  But now I know you are mad."

Like the singer? Kamahl used to say "Why is everyone so unkind?".  Actually, I couldn't have cared less, and was completely unmoved by any of these comments as what I was doing was for my interest and amusement not theirs.

The model that I decided to build was, even I must admit, far too troublesome to build to have wasted it on an experiment like this; but I couldn't help myself.  It was a super light weight, twin boom plane of 58 1/2 inch span, powered by 2 OS.15s.  You can see a photo of the plane here if this post works out as I plan.  The colours don't show too well but the paint was white with flourescent trim.  Pink at the front, fading through orange, yellow, green to plain blue at the back.  It looked very bright in the sunshine.

It had a home made, convertible control system that could be flown on 1 OR 2 wires.  I did the first 3 flights on 2 wires to get the trim where I thought it was about right and to prove to myself that the plane was OK if the worst did happen when I flew it on 1 wire.  It only lasted 4 flights.  It was quite stable, but stuntable on 2 wires.  It was only 4 minutes into the first flight on 1 wire when the ancient plastic of the control bobbin on the handle failed, leaving me with no control at all.  That was just about the only bit that I hadn't made myself. 

I have since been told that the problem was not unknown.  Unfortunately it was unknown to me, but others before me had suffered the same failure.  I hadn't done anything other than climbs and dives at that time.  I had intended to take it easy on the first flight on monoline to prove it from takeoff to landing and to settle my nerves etc.  You know, sort of work up to it.  I had no trouble controlling the plane or staying in front of what was going on.  If the handle hadn't broken, I am sure that all would have been fine.

There was a lot of work in that plane and I knew that it was a risky game to play, but I did it anyhow.  That one will never fly again.  It is already part of a land fill project somewhere.  If you build 'em really light ( and that one was about as light as I could get it) there isn't much to re-build.  I was pleased with it's appearance and had no trouble getting the 2 engines going, or tuned.  The OS.15s pulled it around faster than I wanted, and it left the deck like a rocket.  They certainly gave it some power to spare, but if I ever build a twin again, they would have to be worked on to get them a bit more tractable and to slow them down a bit.  In fact I have some interesting ideas on that score that just invite experiment on another multi engined project.  I don't think that the next one will be monoline though.

[Willis Swindell]

Charlie
I built a combat plane with moonline unit in it it flew great until I got behind on the controls I have a profile with a torque unit in it That I haven’t tried, because talking to Dale Kirn about it he said the torque unit wouldn’t work I needed a Stanzel unit with a plastic worm gear. The brass gear was to heavy and hard to stop. What unit did you use and size of the wire?
The  twin looks like what I need to use my Monoline handle I need weight to keep good line tension
Willis

[minnesotamodeler]

I saw a fella fly stunt with monoline at a contest in the early 60s.  Did pretty well as I recall but seemed exhausting on the pilot. A whole lot of quick back-and-forth with that control hand.

So it has been done!

--Ray

[Ironbomb]

OK, I've heard of monoline, but have never seen one. What is it basicly? a flexible sheath with a wire inside? twist the handle, and wire turns inside? Wouldnt that be heavy for a plane to carry aloft?

I thought about ordering a Stanzel kit with the monoline just to see the setup, but then I remembered I dont have any extra cash anymore

Anybody got pics of this setup?

oh yea, nice twins you guys, specially the Mosquitos colorful bottom side

Greg

[Willis Swindell]

Here are a couple handles and two torque units for a d speed and a jet unit. I don’t have any Stanzel units maybe some one else could post a picture.
Willis

[Ironbomb]

Thanks for the pics Willis. This is a two handed operation? I have to admit, I am clueless on a great many things 

I would like to see a plane fly on this rig

[minnesotamodeler]

Yup, two-handed, one on the handle and the other on the spindle thingy.  Push it forward for "up" and back for "down", unless it's the other way around...I forget.  The spindle runs on a spiral doohickey that spins the line.  The guy I saw flying stunt had about a 3-foot movement on the thing, looked like he was playing "flight of the bumblebee" on a cello or something.  I don't think it's very practical for stunt...or combat...or I guess anything much except speed. Or I could be wrong, what do I know?

--Ray

[Willis Swindell]

I remember in the late 60’s a guy was flying combat at the nats with a monoline unit he would wrap up his opponents lines then kill them they called him monoline Pete. He was booed off the field. I remember that he only moved his hand to control the plane no extra movement at all.
Willis

[Elwyn Aud]

I remember seeing someone fly a pattern with a mono-line unit at one of the VSC's. It was quite a few years back. I believe it was with a Jamison Special with a Fox  29.

[john e. holliday]

Elwyn,

       The only monoline unit I have ever seen flown in aerobatics was flown by Joe Kirn.  The plane was his dads(Dale Kirn) Thunderbird.  Still had the original engine in it.  It was interesting to watch him fly it. 

                                                                           Later,  DOC Holliday

[Elwyn Aud]

That must have been the one. Was it yellow? I have a picture of whatever it was somewhere but it's buried deep. Probably take a month to find it. I think Ken Budensiek had a photo of it in that year's VSC article in Model Aviation.
Edit: Found the photo in the August 2000 Model Aviaton  Joe and Dale Kirn holding a Mono-line yellow and red Jamison Special. Guess my memory isn't all that bad after all. I never got to see the Thunderbird.

[Willis Swindell]

We have  gotten away from twins. When building a Push pull you have to make sure that the stab and controls are sturdy because the prop blast is close to the stab and it will vibrate  or fluter if it is not. ask me how I know. also you really have to have some one who you fly with hold the plane. You have to swap ends while starting you have to know where you can hold and where not to. and when you let go make sure you don’t drag your hand threw the rear prop. If a battery clip falls off the rear engine it is instantly sucked through the prop or any thing else you drop, and some times this will throw a prop blade to add injury to insult. I recommend two engines up front they are easier to start and much safer if you have a fuselage between the engines and props. Experience talking, I don’t bother to take a push pull out Unless I know my flying buddy is going to be there and I know he is familiar with the plane.
Willis