June 2,oo1's
New Stuff
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 UP Dated
  June 28th,  2,oo1

Official USA Time, Hawaiian - Alaskan - Pacific                                                                          Mountain -  Central - Eastern - Caribbean

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Homer Bell's Fly-In
July 13 to 16, 2oo1- Hilleboro, Ohio USA
IMHO, perhaps the BEST experimental helicopter gathering on planet earth.
Map to Homers

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S76B for Sale

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RotorWash International
the web site

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Helico Passion

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Soloy Bell

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HeliCycle - Solar T62

      I am considering a Solar T62 for my Helicycle and want to talk to someone that is using that engine. Could anyone using this turbine or knows someone who is ,please email me. I would like to know any useful info on it.

     A key question is, on an practice auto, is there any trouble rolling the throttle back up at the end of the recovery?

Thank you,
Clayton,

Michael Fuchs bird

  Hi Glenn,There was a photo a while back of a small turbine in Argentina (I assume) with your friend and
  someone else. You promised more info soon and I was wondering of you ever got it?Thanks,Clayton

  Hello Calyton,

  Thanks 4 U're eM to SHnPGIE,

  Sad to say Argentina is having difficult economic times the last few years. This has  causes a slow down on the project.

  Sad to say, no new progress to report................

  Glennnnnnnnnnnnn

Duncan Prentice

Hi Guys;

I hope someone out there can help, I've been trying to contact the supplier for the AW-95 plans, but with no luck. I've sent numerous e-mails to Doug Schwochert but no response.

Does anyone know if he still supplies plans for the "Choppy" ?

Just something of interest, a really good site for someone unfamiliar with helicopter design and mechanics is at www.howstuffworks.com/helicopter.htm This is a good site for info and pics, also further information on the links. Anyway I hope someone can help me out with the AW-95.

Michael Tyler

Q: I have read that I can buy a pipe for my two-stroke engine that makes more power and performance.  How do you feel about the tuned pipe?

A: The exhaust system on the two-stroke is extremely important. Changes in the exhaust will alter the power. That’s true; however, the changes may not be what you want. First, understand what is required for power development in the two-stroke, as it relates to your propeller.

The propeller draws power in a linear fashion. That is to say, with increasing RPM the "load" or demand for power is lineal. An increase in RPM will "load" the engine and the power output needs to match this loading to give balanced performance.

A look at the torque curve and horsepower curve can tell you how suitable the engine performance is to use with a propeller. If the two curves run parallel, then the engine will likely power the propeller nicely.

A nice example of a balanced curve is the type 582-series Rotax. Many flyers of the predecessor of that engine, the type 532, will tell you the two engines are completely different. In the case of the type 532, at some 65 HP, the engine was extremely hard to match a propeller due to a "bend" in the power curve in mid-range. The engine was always reported to have a
"surge" in the 5000 to 5500 RPM range that was totally uncontrollable. Pilots could not hold a throttle position in this range due to that characteristic.

The type 582, also 65 HP, solved this with a more even, lineal, power development in this range. The surge was gone and the engine performed wonderfully in the low and mid-ranges compared to the type 532. (This was accomplished primarily with the use of a bigger bore, from 72mm on the 532 to 76 mm on the type 582.)

Secondly, the engine, without modifications, has a distinct breathing requirement. The jetting for the engine has been developed for a so-called "typical" propeller load.  At idle, your Rotax will have the fuel/air mixture a bit rich, to allow for a smooth transition to mid-range (2000~4500 RPM approximately), and then the engine will have a distinct "lean" mid-range from 4500 to peak torque output at about 5800 RPM. After this, the engine will again be "rich," with
lower EGT readings to allow for full power on climb and take-off. Any change in the power curve, which you can certainly get by changing the exhaust, will alter this breathing pattern. You will need to be extremely careful not to exceed 1200 degrees F at any RPM [and install your probes at the proper location! --ed] to avoid engine seizure. An accurate exhaust gas temperature reading is paramount to jetting the engine if you must change the exhaust.

Your final consideration is that of suitability. If you install the exhaust, you must realize that the configuration of a "tuned pipe," versus your pulse tuned muffler, will alter the power curve. In effect, the pipe manufacturer will rob power from the low end of the engine curve and increase the top end to give a higher peak reading.

The needs of the propeller are not as simple: you must somehow pull the prop from idle to full power, going through the "dip" in torque created with the pipe. The now non-lineal power curve may leave you with some areas of unstable power development for the propeller. The matching of prop pitch to the new power band may be difficult.

The worst case is in the powered parachute market where most of the normal flying is in the low and mid-range RPM of the engines. In that example, you will find a huge surge in the power band that may make cruise flight uncomfortable.

To answer the question in brief terms: I am not in favor of tuned pipes. They develop power in the top end at the expense of some other RPM range in the engine and this causes prop loading and carburetion problems that we do not need. If you really need more power you should consider a bigger engine. I think you will be happier in the long run.