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

I am with Nev and Ozzie. It sounds like a lean out at half throttle which is a little unusual since you say it runs fine at full throttle. Full revs stable at full throttle indicates the fuel flow is fine. Unless the fuel pump is not working properly at half throttle I would be looking at a carburation issue.The rise in egt as the revs rise indicates a lean out; as it leans the revs will always rise if the mixture is correct in the first instance, and as it leans and the revs rise I would expect the egt to rise. It sounds like it then gets enough fuel again, the mixture returns to normal and the revs and egt drop accordingly.

 

I would be looking at the pump and carburation. Is the pump getting a good pulse from the crankcase at half revs? What condition are the hoses and clamps that connect the crankcase pulse signal to the pump. Is it the square or round pump you are using?

 

David

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

Yes BLA82, that second glider looked like he may have known what he was doing. Kept the wings as flat as he could, and more ruddered it around. Pulled it off well with the height he had, but you wouldn't get away with that in most ultralights.

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

My apologies for posting the letter from Greg McDowall twice. The first thread should be used only I guess.

I have just received the following as a result of representations through my local NSW MP.

Basically in NSW Ethanol will be in regular unleaded only.

Phil

=============================================================

Dear Mr Irvine

Your representation to Mr Richard Torbay of 13/12/08 has been passed to me to prepare a response.

You will receive a formal response through Mr Torbay in due course, however I would like give you an early reassurance that the 10% ethanol mandate will only apply to regular grade unleaded petrol.

Ethanol-free premium unleaded petrol will continue to be available for ultralight aircraft and other engines that may not be suitable for E10.

Regards

Greg McDowall

Greg McDowall

Director, Biofuels

Office of the Director General

Department of Lands

Phone: (02) 9236 7655 Mobile 0413 650 851 Fax: (02) 8236 7081

Level 3, 1 Prince Albert Rd, Sydney (GPO Box 15, Sydney NSW 2001)

Email: [email protected]

Web: www.biofuels.nsw.gov.au

On 13 Dec 2008 I wrote to my NSW local state member, Richard Torbay, asking him to make representations to the appropriate Minister seeking clarification of the status of the use of Ethanol in motor fuels, with special regard to the danger to aircraft engines.

I recieved a prompt reply from Richard Torbay saying that he had made these representations . So far there has been no response from the Minister responsible, the Hon Tony Kelly, Minister for Lands in NSW. I await his response, but not holding my breath!

There is a simple test for Ethanol in fuels which is to add a measured volume of water to a measured volume of fuel. Shake it up and remeasure the water volume. Any increase is caused by absorbtion of Ethanol. A graduated measuring cylinder is ideal. eg. if you start with 100ml of fuel, add 10ml of water, and it becomes 15ml then Ethanol is 5% by volume.

Any Ethanol in fuel not labeled to contain it would probably be a breach of product description regulations, or some such and could be investigated by the appropriate authority.

Phil

Quote,

One last thing is your oil. Use the best you can afford. I personally use penrite

HI-PER TWO STROKE. HI-PER TWO STROKE - Penrite Oil

have a look at:

Two stroke engine oil, two stroke engine oil test, testing results for two stroke aircraft engine oil.

and:

How 2 cycle aircraft engine oil works, what makes a good 2 stroke oil, two stroke air cooled engine oil, two stroke liquid cooled engine oil.

Lots of good info and tests of some leading oils.

I use the Pennzoil 2 stroke air cooled. It is actually cheaper than the Castrol 2T here. It comes out very well in the tests and from personal recommendation from a property owner who has lots of 2 stroke machinery and used to own my plane. Exhaust system has no oily deposit whatever.

Phil

Hi Keefe,

Rotax 447. SCSI points type.

Phil

No, I am near Armidale in northern NSW. The Tyro came to me from SA via St George, Qld.

Phil

Hi Wayne,

Mine has a single carby so it is pretty basic.

What EGT and CHT do you get? I am finding that mine shows nearly 450F CHT on full power climb and over 1200 EGT. Only a single EGT probe. CHT only on rear cylinder. This is despite a lot of fiddling with carburetter jets and needle settings. I feel that this is getting a bit close to the maximums.

Phil

I built my own, on my own property. A 3 sided shed 10m x 7m with 3m clearance for about $1300 with S/H colorbond iron and new timber trusses on steel posts.Dirt floor. Houses a Tyro Mk2. Works for me.

Will make a good hay shed if I give up the flying.

Phil

Look also at Rotax engines, Rotax 377, 447, 503, 532, 582, and Rotax 912 aircraft engines, parts & ultralight aircraft accessories. and Ultralights, ultralight aircraft, ultralight airplanes, or ultra lights are also known as microlights or microlite aircraft in Europe. In Canada they also fit into the amateur built aircraft category, experimental aircraft and advanced ultralight air for many articles about care and feeding of Rotax 2 stroke engines and Bing carburetters.

There are also a long series of articles by Mike Stratman which a Google search will throw up. I think they are in PDF format. Very worthwhile.

The Rotax web site is another obvious source.

Is your 447 the single ignition, points model? I have one of these on a Tyro Mk2.

Phil

I have written to my local member conveying my concerns about availability of suitable fuel and asked him to clarify the situation with the Minister. I said that this is a serious safety matter because of the possibility of inadvertant use of ethanol blends if it is not controlled.

I suggest others do the same.

Phil