Is it true that on a piped engine you will have the same power as a standered muffler at low end then as you throttle up you will suddenly get a boost?

well im not to sure about throddleing anything, last i heard that was some kind of sexual favor, but one thing i do know. You can definately break your plane's fuse in 3 when you nose over at full throttle.

Ya, I've got skills like that. As for throddleing, I ment throttleing.

Yea, ill say.

Eric,

A tuned pipe is TUNED to boost the engine's performance, while it is running within a certain RPM range.
Mostly, it is tuned to give its boost at full throttle, maximum RPM.

When you throttle the engine up, it will reach a point where there will be a "step" in the power. The RPM will increase, at that point by anything from a few hundred, to a few thousand RPM, depending on the engine, the application and the pipe.

In most cases, this will occur, advancing from 70% throttle to 100%; breaking from the idle/low speed fuel circuit, to the full load, high RPM fuel circuit, which must be adjusted accordingly.

Please note; the engine cannot be run steadily in the middle of that range. If it "jumps" from 12,000 to 14,000 RPM, the engine cannot be operated at any RPM between these numbers; 13,000 RPM f.e., unless the tuned pipe is removed.

What pipe do you intend to use?

Hey Darzeelon,

Not to discredit your last post. But if the engine cannot remain in the resonance rpm, how can the helicopters then tune their pipes for engines running at almost constant rpm?

No, I would like to see the resonance rpm as where the tuned pipe "sets in", like a turbo that builds upp pressure. The engine can remain at that rpm, but the torque is at its peak.

Also for your info ep124, their are a number of layouts of tuned pipes. There are pipes for high rpms and others for low. Look at the OS 140 RX pipe. It is designed to peak at 7600 rpm!

In the other end, their are pylon racing pipes, designed for engines running screaming at 20 000 rpm.

There are lots of parameters to take into consideration; the length of the pipe, the length of the pipe + manifolder, the design of the pipe itself, the bore to stroke ratio of the engine, and more.

Speak to your dealer, and he will gladly help you in the pipe jungle.

Best regards, Fredrik

I'm thinking of possibly using the jett in-cowl pipe.

fwahlgren - Heli "tuned pipes" are really half phase expansion chamber pipes and are not "tuned" at all. Heli pipes function like mousse can pipes and operate in a very broad RPM Range.

Fredrik,

Please re-read my post. I used the words" mostly" and "in most cases" with a purpose.

Most people who install a tuned pipe, on airplanes and racing boats, want them solely for the maximum, high RPM performance. For people who want to maximize a given engine's performance at relatively low rpm, want this low RPM to be the engine's maximum usable range, with props that are more efficient, like in this [link=http://www.supertigre.com/engines/supg0235-man.html]review on the Super-Tigre .91[/link], or the MVVS tuned silence and full length tuned pipe, for their .61-.91 engines (RPM range 10K-13K).

Adrian added a thing about heli (and car and 3-D...) pipes and their tuned RPM range.

Adrian,

Being an old heli flyer, I must disagree with your post too. (What a pain in the &%/¤ that fwahlgren) .

I have had a X-Cell 60 with a U shaped pipe and a Robbe Futura 60 with a straight pipe. Both of them you had to work with the manifold length to adjust were the pipe set in. Of the two helis the futura had the most "pipe effect" characteristics, hence once reving above a certain rpm, the engine went crazy and continued to accelarate even though you eased of the throttle/pitch stick. It actually was a bit tricky. Of course the Robbe had the OS 60 FX WC heli, which was OS most powerful heli engine then, putting out a whopping 2,4 hp. The X-Cell had a OS60N (?) or sometehing, their more affordable version, which made it a bit more moderate in handling.

I have also had a Kyosho Concept VR46 without a pipe and all I can say about flying non piped helis is: boring!

The conclusion is that pipes truly helps raising the effect. Check out Bollys home page, or weston, or som of the others and you will find some info about pipe theory.

Sincerely
/Fredrik

I was just commenting on the top heli guys I have seen personally. Alan Szabo (spelling?) and other 3D guys do not use tuned pipes because they need perfect linearity in throttle curve to do what they do. They run the new OS 91 FX-H with a large volume expansion muffler and are never short on power.

Here's a link to a vid of what Alan can do:

[link=http://www.cafreestyle.com/Videos/3D/alanszabo.wmv]Alan Szabo 3D Heli Vid[/link]

Absolute fantastic clip Adrian!

I definitly agree that an expansion muffler would be preferred rather than the tuned pipe in heli aplications. You get a feeling of not being in full control of the chopper using a too hot pipe. Perhaps there were more problems than the engine in my case [&:]. My skills stretched to rolls and loopings. I could throw in a 540 too. A bit left to the skills of the guy on the video!

Actually I think the Kyosho VR 46's problem was too small rotor blades, rather than lack of horse power. It can not capitalise on the higher torque of the OS 46 FX compared to the OS32.

Cheers!