twin engine planes

LAST EDITED ON Jan-20-04 AT 01:05 PM (CDT)
 
I have been thinking about playing around with a twin engine plane but I have no idea where to start. I just need to know some basics like tail moments, how to attach the motor mounts to the wing, ect.
I am going to start with a profile, and if I like what it flys like I might move up to a real stunt ship. I am really just trying to have some fun with it. Thanks

Hey Bud,
Glad to see you at KOI!
I'm working on a P-38 for two .32's. Should fly nicely, and it will be a profile to start with, maybe a built up later.
Will talk to you later about it, hven't decided on which airfoil I want to use. About 50-52 in WS, and length to match in proportion.
Also have plans for Jack Sheeks Mossy Stunter (Mosquito) that reportedly flew pretty good on two Fox .35's. No problem to build a profile version. Personnaly I want to stick to a Warbird style, but the Limitation would probably make a very good twin, AKA the LA Heat.
Bill <><

>I have been thinking about playing around with a twin engine
>plane but I have no idea where to start. I just need to
>know some basics like tail moments, how to attach the motor
>mounts to the wing, ect.
> I am going to start with a profile, and if I like what it
>flys like I might move up to a real stunt ship. I am really
>just trying to have some fun with it. Thanks

Derek,

What I know I learned seeing pictures.

The easiest way to make a twin engine model is like making two profile ships that will be joined by the wing and the stab.

The balancing should be the same as in a regular ship.

NOW, if you wnat to make it a one fuse and two engines on the wings I figure you should have the wing ready for them just like on a profile, i.e. the sheeting should ge untill an inch of two after the engines, and maybe a little reinforced. You don't want to have your wing broken by crancking the engines.

The closer they are the safer you'll be.

I read Paul telling about the fuel system for his 4 engine ship.

All four engines shared a bladder tank, and each one had a small nva to keep the fuel flow kinda uniform.

If you choose to have separate tanks keep in mind that the last ting you want is the inboarad engine quitting before the inboard one.

You also need more power on the outboard engine a a hole in the head, both cases will seriously affect line tension.

Disclaimer, etc...

snip
>
>If you choose to have separate tanks keep in mind that the
>last ting you want is the inboarad engine quitting before
>the inboard one.
>
>You also need more power on the outboard engine a a hole in
>the head, both cases will seriously affect line tension.
>
>Disclaimer, etc...
>
>Ion

Besides having a 4 engine B-17, I have had twin's as well. The statements above are not what I found to be true. The B-17 will fly with ONLY the outboard engine. Not well, but not as bad as one would expect. I found twins to be the same, not a problem.

Further, I found best performance when the outboard engines(s) were stronger than the inboards by a small amount.

Don't get too discouraged by the problems above. They are not serious issues, and should not be used for decisions on building or not building a twin.

btw...Good to see you on the forum Derek. I last remember seeing you in Sweden where "it's all working just fine...Why mess with it"! How's the family doing?

Hope to see you again with a twin.

>>>I found best performance when the outboard engines(s) were stronger than the inboards by a small amount.<<<

This sounds very interesting to me. I think you mean something like the outboard prop should be little quicker yes?

For first look it is trivial, the outboard prop is quicker (I mean linear speed) because it has longer lap little bit and thus needs little more pitch or rpm or what. So 2 equivalent props on two sides of fuselage at the same rpm is like to have 4 blade prop on one place with 2 blades little lower pitch and another 2 little more.

My question is – is it really wrong if one (or some) blade has another pitch? … Probably yes, but why it is not bad to have differences in pitch spanwise?

Thanks for the info everyone, maybe when you see me again I will be flying a twin!!

Good to hear from you Paul... the family doing is great!

Paul, lf you are doing the trimming I am sure the stronger outboard engine, since has more yards per lap than the outboard one.
]
BUT, that's a thging that only on the hands of a builder flyer likw you can make much of a difference.

Since the guy is just staring I wouldn'd tell him to intoo such refined quality of trim.

for the first dual engine i still think more inboard engine and duration are, as a start, the safest setup.

God bless,

Derek:

The Moonies have plans for a twinkie profile....I believe that ULTRA sells the plans. Based on a GOTCHA foam wing, no flaps.....as I recall. Steve reported that it flew pretty well, too. Used 2 OS .20's to qualify for "P-.40".

Have fun!

See Ya

Dont forget Brodak's F7F Tigercat kit, might not be stunt...but a good place to start

Derek,

I've have had three twin engine stunters, the last two with retracts.
The first, Sheeks Mosquito, would have done well in any contest.
My current twin, I plan on having at a few contests later this year.
They are fun to fly.
I'd look at the plans that have been published on how they attached things, but it's nothing really that different.

Contact Gordan Delaney and ask about his Too Much. I saw that one fly a lot in the 70's and it was impressive.

Thanks Ty,
I still have that twin,and a new modern twin. Most people build twins too small. They fly better on the wings than on the props. If you figure the disc area on a 13 in. prop then figure the disc area on two 10in. props you see why they pull a large airplane. My old two Much was 960sq.and flew with two fox 35`s.Marks twin flight streak flew good also. 72 in.span with flight streak fuse. With a longer stab.and elevator that went all the way across to the two fuse/

Have fun
Gordy

I,ve seen Gordons,Plane (Too Much) fly at vsc. Big plane 2-fox 35s.
Did well in the hands of Bart Kaplinski and Gordon Delany.
Appeared to pull like a wild hog.
Nice to see you back Derek!

Big deal, Charlie -

Klapinski could fly a 500-point pattern with a Wisniewski "Pink Lady" )

(Just in case you're not old enough to remember, that was a C/L speed ship back in the 60s) )

derek at koi you said about needing a oriental build twin like a f-82 mustang or like bill said twin limitation . alan

What do you want from a twin? I have a twin Ringmaster FP 15 Power and 4 inches added to the wing, its the greatest flying Ringmaster I have ever had, and I had many. I flew it at Brodaks just for fun, but thats what I do (have fun) The sound is great , a real attention getter. Its not for competition , but its fun to fly.SEE YA NEAL:)

Neal, Pat Rowan sent me a pic of the twin Ringmaster. It looks great and like a lot of fun to fly!

Actually, the Urtnowski B25 would be nice.

Any advice as to thrustlines? I'd heard somewhere that the outboard engine(s) should have some right thrust.

>Any advice as to thrustlines? I'd heard somewhere that the
>outboard engine(s) should have some right thrust.

That is what I did on my last Twin, about 3 degrees or so.
It would fly up at 45 degrees with good line tension with just the outboard engine running, I think it would have looped, but never worked up the guts to try it.
In fact it felt better than with the outboard engine stopped, it seemed to "crab" badly like that.
Mine was more-or-less Mercury Crusader numbers with 2 OS Max25's. ( the old loop-scavenged ones , not modern ones )
56 inch wingspan, foam wing, it weighed 75 ounces but flew quite well.

LAST EDITED ON Jan-22-04 AT 05:02 AM (CDT)
 
Ian Peacock designed some profile twins:

[photo not recovered: CL1168.jpg]

and

[photo not recovered: MAG46.jpg]

are available from:

http://www.nexusonline.com

and an ME110 that can be got from Phil Hannson - he also has the Mosquito probably (email me for his address if interested)

Tony

The first twin I built was the Me110.
It flew very well, but I think ( in retrospect ) it could have done with more wing area, or a thicker wing....
Or, maybe if I was a better builder I should have built it lighter...
Don't get me wrong, it flew well, went everywhere I pointed it, really it flew better than I could fly at the time.
I first flew it with 2 Veco19's which I could not get on with....
Then I put in 2 OS25's, the old loop scavenged type ( now 25 years old, I still have them )Right up there with my favourite engines, smooth running, easy to start, .....
OK I'm rambling and " tired" got to get to bed......
Happy Flying from Oz where it has been a nice cool 20 to 25 degrees Centrigade for most of January.
Please note I will "celebrate" my 56th birthday on Saturday 31st of January...... please send my presents to...********************************* ( deleted by Censor )

Only joking, happy flying to all

>I have been thinking about playing around with a twin engine
>plane but I have no idea where to start. I just need to
>know some basics like tail moments, how to attach the motor
>mounts to the wing, ect.
> I am going to start with a profile, and if I like what it
>flys like I might move up to a real stunt ship. I am really
>just trying to have some fun with it. Thanks

Hey Derek, Here's a picture of the Classic legal Twin Flight Streak I fly in Classic. 74 inch WS, a pair of OS .20 fp's. E-mail me ifyou want more information.

I'm wondering why everything is spinning around?

I built a twin Flying Clown with two OS 15LA's. The plane flies great and it's quick, about 3.6 second laps on 60' lines. It's a real attention grabber and the plane has no bad habits! Super-Fun.

I'm so excited about twins I building a twin Buster with OS 25LA's!

Here is a picture before the covering.

Why didn't you run the sheeting all the way through the center section to tie the two vibrating engines to a firmer structure?

That's what I did (intuitive engineering) on my twin Combat Streak back in the day.

Cy.

The OS 15LA engines have no vibration, very smooth. If they were Fox Engines it might be a problem.

Thanks for everything guys. I think that I am going to build a twin Limitation to see what it is like. I cant wait to get started, I just have so much other stuff on the bench that it may be a little while before I get to it. I will post pics when I do though. Thanks again!