newairly

Surprising how things come from the past. The Tyro shown in the picture is 19-1219 which I bought nearly 5 years ago, but have not flown for 3 years. It is quite sensitive in pitch, but not difficult to get used to. Having the stick nice and close certainly makes it easier. A bit like some gliders I once flew where you could just rest your arm on your thigh and just use your fingers only most of the time. The thing I found difficult with my Tyro is the lack of much pitch stability making it difficult to trim for a constant attitude. This probably comes from the stabilator which has no anti servo tab. It is hinged at the centre of pressure so seems to be happy to stay wherever it is put. Phil

I have wondered for a long time why the administration of gyrocopters ended up in a separate body to most of the rest of the ultralight fraternity. Gliding I can understand because it has been around for ever. What is the history behind the separate organisations. Phil

Maj. That is in interesting bird! Is it based on any WW1 plane? Is it still around? The fuel I used for the recent ground test is premium unleaded (95 octane) with Pennzoil at 50:1 It was mixed just before use. Pennzoil still seems to be the best 2 stroke oil around for air cooled engines. The tests that I found 3 years ago rated it the lowest ash and best performing on a comparison test using a Rotax 503 (I think). Rotax say that 91 octane is OK but certainly no ethanol! Not too sure about the 91 octane. Incipient detonation can cause a sharp rise in temps so higher is safer, especially as octane number drops on storage with mixed fuel/oil. I may even go to 98 octane unleaded. The surging is quite slow. A period of 10-15 seconds. EGT at full throttle is 1150-1200. at part throttle, 5500RPM EGT is 1050-1150. My CHT also approaches 400F at full power. I am trying to get the Tyro going again after 2 years of not flying. One of the reasons I stopped flying it was because I was not happy about the engine, especially the part throttle problem. Phil

The pump is a square type. I also have an electric boost pump so I can try that to see if it changes anything. However because full power is fine, even for several minutes, I feel that it is something other than fuel availability. I have seen some references to surging when the mid range fuel circuit in the Bing is nor working correctly. Also effects from the exhaust tuning. However the exhaust is Rotax standard. As you comment the change in EGT is what is expected with a leaner mixture, as is a rise in RPM. It used to be OK so what has changed!. Very annoying. The next thing I will check is input manifold leaks. Phil

I have a Rotax 447 fitted to a Tyro Mk2 The Rotax is single ignition, single carburettor. It has a single EGT sensor and single CHT sensor on the cylinder nearest to the flywheel. My problem is that at part throttle the RPM will not stay steady. I see this both in the air and on the ground with the A/C restrained with a tether. The RPM will vary from, for example, 5200 to 5700 with steady throttle. As the RPM goes up the EGT also rises to about 1150F. When the RPM drops so does the EGT . This is on the ground so I have plenty of time to watch gauges. This suggests to me that it must be a mixture effect, but what? The full throttle RPM, on ground, is about 6350 which sounds about right. Fuel is 50:1 premium unleaded. Where can I find information which might help resolve this? Phil

You mention platinum plugs. What is the difference between iridium and platinum plugs? My car uses platinum plugs with a recommended replace period of 100,000Km. That's a lot of hours. Phil

Having come from a gliding background, attitude for speed and spoilers(throttle) for angle seems natural. If I start to sink on final the automatic response is with throttle. I want to keep my speed at around my selected approach speed and this is usually near best glide in any case for most aircraft. Phil

If you just want to read it, it is in Armidale Dumeresq NSW Library. Your local library can get it on inter library loan. Phil

Whoops, try http://www.casa.gov.au/fsa/1999/jul/FSAinst.pdf Phil

Have a look at this article from Flight Safety Magazine in 1999 http://www.casa.gov.au/fsa/1999/jul/FSAinst.pd It discusses the use of a venturi as a backup system to a vacuum pump. Phil

Looking at the elevator, which seems to be full up most of the time, it seems to me that the speed was too low and he was just pulling it into the air and then stalling. Scary stuff. Phil

I think it is to allow a smaller diameter for the same power absorption. Less stress and maybe better efficiency by avoiding near sonic tip velocity. I do not see much application for light aircraft. Phil

With gliders I was taught a constant angle circuit. The idea was that wherever you were in the circuit you could reach the aiming point with half spoiler. It was, I guess, really rectangular with very rounded corners, and of course being a glider, continually descending. This seems a good idea if you also are in a high drag/low inertia aircraft with a possible unreliable engine. Ie. do not ever get out of gliding range of the runway. Phil

The low drag and high inertia of a glider enables more energy to be recovered. It may have traded velocity for lift during that incredible low turn. Racing gliders routinely do a low pass at a finish, dropping water ballast, and pull up enough for a full circuit! Phil

I just came across this web site with a lot of articles about Ethanol blends Gasoline Expiration - Ethanol Blend Fuels Have a Short Shelf Life and related pages. One thing I was not aware of is the very limited storage life of E10. They claim 90-100 days under ideal conditions. Non Ethanol blend fuel can be stable for up to several years. Phil