Huge model airplane props...

General Messages Post you pics as well

Postby JPXman » Tue Apr 27, 2010 11:50 pm

i will say:

its tough being a lone wolf in the lazair world, but the internet shortens that gap a bit.

but nothing replaces meeting other lazairheads and looking over their machines. i was a lone wolf when i started into this "hobby" but had a good resource i could always call on the phone.

if you are building or re-building a lazair, try to find a few guys locally you can shoot the bull with who are flying lazairs of their own. for example, don't poo-poo the boat wrap thing too quickly - that covering technique is being incubated by a very dedicated group of lazairheads in ontario. they are all taking the baby-steps together all at the same airfield. a great way to learn the lazair.

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Postby Shannon » Wed Apr 28, 2010 6:16 am

Tyler you say "lone wolf" ? If you don't mind me asking what is Daffy's status ? We know he put a lot of effort into his plane and hangar but have heard nothing lately.

Josh there are many directions you can travel and what you choose to do is ultimately up to you. I will say that usually it's less painful in the long run to go with many proven things.

My opinion is that the P-tips are the cats meow. They are far too expensive in my opinion but are worth the extra money to me. If you plan on flying a Lazair from now on they are a good investment (long run thing again). The Clarks (atleast the ones I tested) worked just fine but in my opinion are not ideal. Too bad the design can't be refined a bit. Because of the thick airfoil cross-section on the prop it seemed to me to slow the engines down just a tad too much. This narrowed the RPM operating range from min to max power to a smaller margin than I like. The Bi-props work acceptably and are super super durable. They are great props but a good bit of potential thrust is lost with them. A guy learning to handle a Lazair may want to use them just in case something happens. I recall one guy who broke a P-tip during taxi practice years back. Other suitable looking props, like Tennessee Props for example may be too heavy for small crank Rotax's. There are many previous discussions on this subject to be found here with a little search.
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Postby JPXman » Wed Apr 28, 2010 8:57 pm

i was saying when i started 10 years ago i was a lone wolf. daffy was the catalyst to my hands on lazair training. but that for me only started about 5 years ago. for me, 2 kids and a demanding job take away a lot of fun time but right now its a rewarding trade.

daffy i think is regrouping for his next assault on his EC. i for one can't wait to see what happens :)

of course without your advice and guidance, i would never have completed the rebuilds of my lazair's shannon. you are the modern guru.
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Postby Shannon » Thu Apr 29, 2010 8:55 am

I see, makes sense. Also I was thinking maybe Daffy had sold out or something.

Haa Haa, we are all Lazair Guru's by my calculations. All a guy has to do to be a "Guru" is not disappear after a few years like many guys. For many it seems that the Lazair (or Ultralights or even Flying in general) is just a passing fancy.
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Postby uscgairdale » Fri Apr 30, 2010 7:56 am

Hey, I resemble that remark! I'm still lurking around in the shadows to jump on a Series III or EC (dreaming). My brother's series III has been taken apart and it's just sitting now, maybe I should just take it for myself.

As of lately I've been messing around with some CGS Hawks for the new owner. The new Ultra is my redesign/build and it just won reserve grand champion in the UL catagory at Sun-N-Fun. Yes, its a real UL. It does pretty well in performance, but its definitely no Lazair.

My current plane is a Varieze. Thought that I would trying going fast for a change. Maybe one of these days I'll zip over to say hey to Shannon.

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Postby Shannon » Sat May 01, 2010 11:14 am

Congratulations Dave. That is pretty darn cool. I see you have already posted some Hawk videos. I wish I had 28-30hp on my Lazair. Two lightweight 15hp engines would turn the Lazair loose. Too bad that back in the day the WAM 342's didn't make the cut. Let me know if you decide to make a flight over.
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Postby Chappy » Mon May 03, 2010 7:08 pm

Dave,

Where was the Hawk located this year at SNF? There were so few Ultralights there I basically gave up spending much time at the Paradise City area. I'm sorry I missed seeing this part 103 Hawk and meeting you!

I guess I was looking for "new" stuff, and a Hawk just didn't register as possibly being that in my mind. Or even an Ultralight, for that matter.

Shannon,

The WAM, if fitted with a prop speed reduction unit and smaller, lighter prop, would have very likely been as good as, or better than, most engines available at the time. It was, after all, freshly certified in Europe for military drone installations and had been run through rather grueling testing. It was built in a brand new state of the art facility. I remember it being very nicely finished. It was, ultimately, not suitable for powering a huge prop bolted directly to the crankshaft that limited the engine's rpm and output to around 13-15 hp. Although one would consider this a de-rating of the output, the huge torsional loads on the engine's crankshaft caused 100% crank failure or damage in all the engines Ultraflight tested (10 that I know of) at the lower HP output. The crank flexed so badly that the flywheel gyrated about and kissed the ignition modules causing them to fail too.

A number of KFM engines, with a more robust crank, have had crankshaft failures for the same reason.

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Postby uscgairdale » Tue May 04, 2010 6:11 am

Unfortunately I was not there this year because I had to go on a trip for work. The new owner of CGS could never have redesigned the Hawk back into 103 status, mostly because almost no one out there takes the right approach in my opinion. It's no suprise what really works to meet specs and performance.....build the airframe light and strong. Part of building light is to select the appropriate engine, not just the biggest one that will just make weight. The Lazair is perfect example of that. The MZ34 engine from compact radial engines weighs in at 42 lbs with exhaust and both electric and recoil starters, not bad although having both starters is a waste. The whole airframe weighs 239. It's ok, but I really didn't think of it winning any awards, George or Shannon's Lazairs would have blown it away.

It's really cool to hear more about the WAMs, especially how the cranks were failing at the lower direct drive rpms. It just goes to show people that you can't just bolt something together and expect it to work. Most KFM failures that I knew about were in the early Challengers, mostly due to overheating with poor airflow and poor instrumentation.

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