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PostPosted: Sun Jul 19, 2009 1:39 am
by sustainflight
Thought I'd have to wait forever to get calm conditions for my first flight of the Lazair 2 (I live in Oklahoma). After making a flight, I state the obvious; it's a lot different than flying a Mooney. Think I need several more flights in very benign conditions to get the hang of it.

Engines started and ran per book, ~1450 rpm at idle with slight 4-stroking until getting up past ~3500.

I looked like a drunk at first taxiing, then got a bit better at coming in early with a little differential thrust rather than weaving all over. Definitely good advice to run the engines up and make sure they're even before releasing brakes on takeoff. Forgot that once and one engine hit the power band before the other; aborted and did it right...

I was practicing taxiing around for about 15 minutes after the flight. The left engine died and would not restart. I saw a bit of air in the line just after the engine died, but it almost seemed like a surge back the line. Put a prime pump or two and the fuel was certainly being delivered, but engine would not start. Reckon I fouled the plugs doing so much low-power taxiing? Grabbing the manuals (torques and other techniques) before pulling plugs. Suggestions?


PostPosted: Sun Jul 19, 2009 11:39 pm
by sustainflight
> Reckon I fouled the plugs doing so much low-power taxiing?

The plugs were fouled; they looked sooty. Put in new plugs and it ran fine.

PostPosted: Mon Jul 20, 2009 1:07 am
by JPXman
don't know what carbs you're using, and what adjustments you have, but if its 4-stroking below 3500rpm and fouling after 15 minutes of taxiing, sounds like you can lean the low jet out a bit without danger of ruining anything.

take 30 minutes one day and play with tuning the carb. when i first got into lazairs i thought you set the carb and left it there forever.....oh the innocent early days. now i find flying from one day to the next, a 10 degree difference requires a little tweaking of the carb jets.

good work getting up and down in one piece! not many of us have flown 2-seat lazairs so a tip of the hat to ya.

"my garage has to be done by july 31st or i'm in trouble"

PostPosted: Mon Jul 20, 2009 3:33 pm
by sustainflight
This Lazair 2 has the KFM 107e engines with Dellorto OVC carbs. There's idle mixture and speed; no high mixture adjustment. The manual has a section on adjusting that I'm browsing. Before leaning, I'll move the EGT to the 260 mm location instead of about 26 mm so I can tell if by leaning I'm getting too hot.

Apart from much lighter wing loading than I'm used to, the "not quite a taildragger" aspect of the two seater is a bit weird. I'll just fly several times in very benign conditions to get the hang of that.

First time I flew it was with Dave in Mobile AL. Couldn't figure out why my jaw was sore. Turns out I was grinning non-stop for half an hour...


PostPosted: Mon Jul 20, 2009 9:31 pm
by uscgairdale
Continue to pick and choose your flying days and you should do fine with the flying side of things. The egt holes were always in the wrong spot according to the manual, but I was always able to get consistent readings. If I were you I would contact Don Black about getting a different jet setting to lean our the mixture just a bit. The egt should be able to handle the leaner mixture and help to reduce the chance of fouling plugs. I fouled plugs only once and that was after alot of taxiing with the 34x20 props. The better 34x16 props helped to reduce that by allowing for a faster idle rpm and more importantly get more rpm and power out of the KFMs. According to Don, Ultraflight never put the right props on the KFMs because they already had the 34x20. I'm guessing that's becuase they had a bunch for the Ultra 342 that never panned out.

Congrats on the flight,

PostPosted: Tue Jul 21, 2009 4:11 am
by ozzie
G'day guys
have you thought of talking to the people on the moni yahoo groups, they have heaps of experience with these KFM engines. may have some good tips for you.
just a thought

PostPosted: Tue Jul 21, 2009 5:01 pm
by sustainflight
Thanks guys,

Joined the Moni group awhile back. Mixed quality of responses so far, but it's a resource. This group is extremely informative and practical!


PostPosted: Wed Jul 22, 2009 3:01 pm
by JPXman
yes exactly dave! so your new props that you got (well new to sustainflight) were 34x16 and what did that allow the KFMs to spin up to? i recall they achieved peak HP around 6000rpm!

i am a week away from finishing my garage, then a month on the house finishing things up, then baby #2 shows up, then i get to spend nights rebuilding my project lazairs and tweaking my JPXs - I CAN'T WAIT!

sustain flight - what have you currently settled on as a priming method?

Edmonton, AB

PostPosted: Thu Jul 23, 2009 7:02 pm
by sustainflight

The KFMs with the 34x16 props make 5050 rpm static and I'll have to check the rpm at 45 mph ias in level flight once I get more time flying, but I think it's below 5600. Red-line is listed as 6600.

Definitely operating at low percent power, but it might be okay because of lower noise, better prop efficiency, and probably lower fuel flow. Would be interested in seeing how quickly prop efficiency drops off with rpm before re-propping.

The KFM 107e operations manual shows:

50% power at 5000 rpm
60% power at 5313 rpm
70% power at 5593 rpm
80% power at 5848 rpm
90% power at 6080 rpm
100% power at 6300 rpm

I'm currently priming with bulbs, but inclined towards an unbroken line to a submerged fuel pump with check valve in the tanks if I can find the hardware.

PostPosted: Mon Jul 27, 2009 2:14 pm
by sustainflight
My right front tire went flat (the 2 seater has a tire in front of each pilot). In this case, it has tube/tire on Azusa nylon wheels with metal bearings. They mount on a hollow 5/8" OD axle.

I dropped the axle off, removed the brake pedals and oversize pipe outboard of the flat tire and tried to slide the wheel off. This should be similar to the one-seaters. No go. Tried some penetrating oil. No go. Tried soaking in penetrating oil all afternoon. No go, not even with hammer taps. Tried unscrewing the bolts holding the wheel together and pulling just the outboard half so I could at least get the tube off to patch. No go; outboard bearing will not slide on axle. Currently soaking some more.

I am speculating, but do you guys think it was a tight fit when built, but then minor deformation of the axle through use and tightening bolts have left it sufficiently out of round that I'll never get the wheel off?

My preference is to put it back together stock, but at some point (particularly if these parts cannot be reused), I'd like to either make it a real tail-dragger (mains forward of current position) or a tricycle with steerable nose wheel(s). The stock 2-seat config requires the nose wheels when you add power. It also shouldn't be so hard to change a tire.

I have a big ambition to fly a multi-engine amphibian, but suspect the weight penalty on the Lazair 2 would make it a really slow 1-seater. Might still be cool enough to consider.

Do you guys know of any kits or examples of landing gear mods for the Lazair 2 that helped ground handling and/or made maintenance easier?