Is a twin turbine powered F-15 a good option ?
 

I find it way cooler to use two smaller turbines than using a big turbine and a bifurcated pipe.
Weight would be higher I know, but an F-15 provides lots of wing area.
What are the real pros and cons ?
Now that some turbine feature in flight restart, it might be time to try that out ?
Thank you for your input.

Twins are cool. But given the experiences I have had just keeping one turbine running, I personally won't consider a twin, even though I would love an A-10, F-14 or an SU-27 twin. I have watched a couple twins in the club and they all wound up in the trash can relatively early in their lives.

The weight is one thing to carefully consider. You can get to the point that you need more power than you can squeeze in the plane just to overcome the weight and you can wind up with an under-powered plane. It all depends on the plane.

I am waiting for someone to be on the cutting edge and put a single turbine in an F-15 on one side. Years ago I flew a Byron F 15 ducted fan and I can't count how many times one engine quit. The plane would fly around fine on one engine with no bad habits. It was just slower.

Depends on the model... the 1:9.5 are way to heavy with twins.. the 1:7 scale no problem!!

Hi,

The few times I built twins, they seemed to load out fine and fly fine. My twin P-120 powered F-18's were both lighter (AUW) than all the single 200-powered ones I'd ever heard of.

One of the really problematic things with twins is if you have a flame-out it's quite difficult to determine which side quit in a short time. The other is that as mentioned, if the single engine performance is marginal, you're asking for trouble, just like a full scale.

With the newer turbines now starting to come with auto re-start capability, I think that alone will make quite a difference in the survive ability of twins.

I have a twin engined Mig 29, two JetCat 140rxis.

Engines are the least of your problems.

I had had a flameout just after lift off on one flight, ( very old tubing in one home made hopper tank, the other with Tygon was fine ! )
The model was safely recovered on the remaining engine with careful handling using the techniques very similar to that used on the real Canberra, a twin with demanding handling on one engine.

Determining the failed engine is quite easy, the model will always roll and yaw towards the dead engine.

The only aircraft I know off which rolls away from the dead engine was Concorde when the spill doors open !

Like the Mig the F15 has large double fins and close to centreline thrust, so should be an excellent candidate for twin installation.

Other types, such as the Me262 ( a real handful on one engine, as related to me by Eric Brown who had flown one, it had a se safety speed of around 180 knots) the Meteor and the Canberra ( se safety speeds of 140 k) would be very difficult models in the event of an engine out scenario.

I say go for it!

David G.

Like Brian says it depends on the size. If its the bigger 1/7 scale then twin is real nice. 1/9 scale then a single.

Pic below is my old 1/7 scale I sold single engine and my friends twin F15E.

I had my 1/7 and a friend had his 1/7 at Kentucky jets and we did allot of flying together. His was twin K140s and mine was a single K210.
His had a longer flight time lower fuel burn and allot more power. Mine had better sound and because of the lower power mine seemed to fly at a more scale speed. If I was building the plane all over again it would be twin for sure. I am about to start building a skymaster F18 and it will be twin.

Pros of a twin
-redundancy encase of failure. (if its a newer kingtech engine it will also have auto restart.)
-Less fuel burn
-cheaper and less likely to fail pipes.
-lots more power
-lower throttle setting for flight

The pros of single
-Better sound with the Y pipe.
-less complex
-lower cost

http://www.rcuniverse.com/forum/atta...mentid=2191525

Long turm future build is a twin Gloster Meteor, thinking two K45 :cool:

here is my 70mm

http://www.rcuniverse.com/forum/atta...mentid=2191526 http://www.rcuniverse.com/forum/atta...mentid=2191527

TB

Hi,

Nobody has mentioned one of the other big 'cons' of twin installation: All the time you spend standing there wondering, "Oh crap. Is one dead?!?!" On my F-18 (my first twin), I was VERY unaccustomed to the quiet sound of straight pipes in that plane. Add to that the quiet sound of a P-80SE at half throttle. I spent the whole first flight nervously convinced that I'd already lost an engine. Finally, my spotter suggested I point her straight up, and straight up she went (again, at half throttle on twin P-80SE's) and it was like watching a video of a shuttle launch with the volume turned off. Spotter says, "Uhh... it ain't gonna do that on one engine."

I never had to try to land it on one engine, but I did experiment with how low a throttle setting I could perform a missed approach. I was able to clean up, climb out of a missed approach at about 25 degrees and land at about 1/4 throttle. With the thrust lines so close together, I was pretty confident that the bird could do whatever I needed it to at full throttle on one engine.

My skymaster F18 will have tail mounted engines with no pipes. The engines are offset so they point out some encase of engine failure it will fly fine. This also is the reason if you go twin you should go with an engine that will fly the plane on one engine IMO. Will be going with twin K160s in my new plane. One will fly it ok.

With all the new telemitry can't you simply put an alarm if one engine dies?

TB