ETLB Squawk Forums — Archive

What climb rate might a flat top himax
Expect with a Rotax 277? I am concerned
about the CDI ignition of the 377/447
failing unexpectedly. I understand that
the 277 has points. Points tend to let
you know when service is needed.

I had a 377 long ago on another ultralight.It was points ignition and used to run very well.

Thank you!

I actually briefly flew a himax 1700 with a 277. empty weight was 320lbs and had a single 5 gallon wing tank. I weigh 178lbs. my climb rate was very marginal, 300ish ft a minute most days, cruise speed was 45-50mph at 5800rpm. I think it would be ok if you were a light weight guy 170lbs or less and the plane was close to the legal UL weight, The original team himaxs' had 277s and weighed in around 270lbs I think (flat top with the lite tail setup). George Sychrovsky is the only one I know that came in close to that though, I think his Himax weighed around 280 with a 277?

One can see the performance specs for George S's Himax here: http://curedcomposites.com/himax.html

I saw George and his plane at a fly-in at Fulton County airport (NY0).  I believe he flew from his home field in eastern Massachusetts, a flight of about 200 miles.  He had cleaned the design up considerably and it had no shortage of climb performance, or cruise evidently.

Quoted from mullacharjak
I had a 377 long ago on another ultralight.It was points ignition and used to run very well.

The same on mine ciao

Great help.....thanks!

I have a 447 with CDI on my Air Bike. No problems at all and I would expect slightly more power. No way to prove that though.

I have many hours in a early 22" wide flattop 96 (now 1100) MiniMax with a 277 and meets Part 103.  Generally fly from runways 200' to 600' above MSL, both paved and grass runways over the past 24+ years.  My weight is about 190 up ,age dose that to you, to 210lbs.  Apply power, lift off is within about 200' to 300' depending on temp/wind condition. Climb about 300' per min.  There have been times I would have liked to have 447. for getting out of a strip that was to short or trees to high at the end of the runway. However, with experience and age one learns to accept, enjoy the challenges of the limits of Part 103 aviation. Just as note, I did modify my fronted to accept a 447, but stayed legal with the 277. Bottom line is to know your limitations and live/enjoy life within them.  Reduce the weight the better the rate of climb. ENJOY the MiniMax for what it is.
BobN.

Without starting a new thread, I have a couple of questions for 277 folks.  I'm breaking in an overhauled 277.  I have a Tennessee Props 60x28. With that prop, I began the break-in and when going to full throttle, at about 6000 rpm and 3/4 throttle, the engine sound goes to a distinctly higher pitch, is that normal? Is it because the carb is operating on the main jet at that point? If I open the throttle further, the engine speeds up to 6800 rpm before it is wide open.  So I stopped the break-in there and bought a 56" Ultraprop II.  With 11° pitch blocks which I believe make the pitch about 30", the high-pitch engine sound now occurs at 5500 rpm and I can safely run up to 6500 rpm (stable cht and egt, 425° and 1000°).  I'm thinking I need 12° or 13° pitch blocks in order to get to WOT and for flying. Maybe longer blades as well.  I'm pretty light at 440 lbs takeoff weight so I think the 56" blades might be ok. Thoughts?

Quoted from Bob Daly I began the break-in and when going to full throttle, at about 6000 rpm and 3/4 throttle, the engine sound goes to a distinctly higher pitch, it that normal? Is it because the carb is operating on the main jet at that point? If I open the throttle further, the engine speeds up to 6800 rpm before it is wide open.  

The Kawasaki 340 / 440 operating instructions supplied by JBird mentions this :
A tuned exhaust, depending on action of type ( and connection length ) will kick in with a slight surge at approximately 5800 rpm.

Is that change in sound at 6000 rpm caused by the exhaust kicking in ?

BobD
Can not comment on high pitch as my hearing has gone south.  However the following  article might help. http://www.ultralightnews.ca/rotax/breakin.htm
I was in on some of the testing of UltraPorp II.  We were told, at that time. not to exceed 6600 RPM.  Maybe Bob Davis has revised that.  Very fellow to work with.
BobN