Hi,

I'm communicating with a pilot in Germany about building a Y/A F-18 for him and this came up. He isn't enthusiastic about using a split pipe because he's concerned about it being noisier than a single pipe. He sent me this photo of how he planned to install the engine and pipe. For me, this was a jaw-drop moment, but he says this is very common over there.

Have any of you flown like this? How are you dealing with the obvious problems an install like this would cause??

I've never done it or seen it done but really I don't see it being a ton of issue. With the thrust line of the jet offset (just one pipe on one side) in this case the thrust would cause the jet to yaw right, with the angled tailpipe, that direction would cause it to yaw left. It wouldn't be consistent at all power settings but it probably does an adequate job of cancelling each yaw issue out. Just my thoughts.

I have herd of several people doing that........... IMO its just wrong lol. If he gets a good pipe then it will sound better then a single pipe. My F15 sounded better with the split pipe then the twins did with single pipes.

Not uncommon in Europe

That just seems so wrong!

Many things can be done differently and with good results. Here in Europe we tend to smirk a bit to builders over the pond who in many cases build their planes like a tank and then say its not a good flier.. no pun intended.

Well,

I'm with you on the overbuilding thing. But if the potential for a louder plane is the only problem, this seems quite a huge 'solution' to it. Does anyone have any video of a jet flying with this setup?

Check Grumania jets Eurofighter. 1:8 scale with one pipe is designed for 80-120N , one VT80 flies it pretty good with one pipe only. I seriously considered it as my next project.

Of course I must also admit that there has to be some thrust issues at low speeds unless its perfectly aligned.

Should run the thrust line through the 3D center of mass. (for least trim issues). I heard they fly fine, F-15 was the one I know about.

I hate bifurcated pipes. That noise is lost propulsive force. I had one of the best ones made and started burning holes in the crotch after 65 flights.

I have seen this Comp ARF Mig 29 flying at Jetpower on a one engine installation. You can see that the smoke is from one side only. They use the second side for a parachute. I seem to re all this was a quite low power installation. The single engine installation is much quieter and needs less power.

John

https://m.youtube.com/watch?v=V6Qxg87FLOo

Shaun, just remember that it's quite common over in Europe to drink wine all day long, that pic looks like about three bottles worth, HA!

I've seen discussion on this before:

http://www.rcuniverse.com/forum/rc-j...ne-option.html

With the pipe angle offset I could see it working pretty well; with a gyro I could see it working even better. It would weigh less and you wouldn't lose as much thrust as through a bifurcated pipe.

I dont believe the pipe is a straight shot out the back. I would like to see the pipe to see if there is not a jog in it.

This F-89 was flown with a single turbine off to one side

https://www.youtube.com/watch?v=8oKOGZlkfi0

I remember henke did some tests to install a single kolibri in the readytofly yak, he also used an angled pipe and was describing various results at various angles until he found the sweet spot he was happy with.
In the videos it was flying really well.
The only problem I see with this is in case of strong thrust + low speed, where the angled thrust would push the plane to the side and a little offcourse

Many years ago I did a yellow F4 and ran single pipe through the middle straight. It only meant losing a small amount of the inside of both exhaust ducts