OS 46fx

Hi All The other day on my 4*40 with a OS46fx the engine went dead..This engine came out of another plane..Never a problem with the engine..Getting back to the dead stick I was using a APC 11x4 the old timers were saying the prop is too small and cause the engine to die..Also that day the Temps in NJ hit 95..I think the 95 tepms had more to due with the dieing of the engine then the 11x4 prop..Yesterday it was much cooler in NJ and I flew the 4* with an

11x6 MA prop. only 1 flight but no problems..I would like to hear from some of the engine experts, on this matter..

Thanks In Advance Dan

Reply to
DanNJ
Loading thread data ...

As an aside to the OS46. A chap at our club came down yesterday with a OS 46 with a tuned pipe, and a 8X6 prop put on the tacho a it turned at 16,000 rpm.

Reply to
John Hollinshead

Actaully a 46 with a tuned pipe should turn something like a 10X6 at those RPM, or even faster.

Reply to
Frank Costa

On 6/14/2004 7:06 AM Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge:

Sounds like the temperature and very possibly the nitro content of the fuel. I use 10% and have had no problems, however there are other people at my field using 20%+ nitro and consistently have problems on hot days.

Reply to
Ted Campanelli

Any good .46 should be able to turn that WITHOUT a tuned pipe! That isn't much load. Supertigre .45 and GMS .47 can both turn a 10X6 near 15K.

Reply to
Paul McIntosh

An 11X4 is on the low end of the desireable range, but the higher heat more likely affected the mixture than the prop. With higher heat comes less dense air and you need to lean the engine slightly more. This gives less power and the 11X4 would be more suitable.

FWIW, I flew for years in the Phoenix summer where temps regularly were

95deg when I got up in the morning. Never had any heat problems, maybe because I let them run a little richer for the extra cooling of the fuel coming in.

Reply to
Paul McIntosh

An 11x4 is a little on the low pitch side for a 46FX, especially in a model with as small as and with such a low wing loading as a 4 Star

  1. Try a Bolly 11.5 x 5. Of course it doesn't matter how low you prop any engine if you know how to use the throttle and have ears.

Too lean a mixture with too high an RPM will cause overtemp & or detonation, whichever occurs first. This could of course be exacerbated by nitro content, oil type/content leading to a dead cut and even seizure, especially on an extremely hot day.

Reply to
K

I run my 46FX with a 12X8 and 5 or 10% nitro - whatever is in stock. It runs great on that. It is not uncommon for the temps to be in the 30'C range here is S. Ont. in the summer. I tend to run a tad rich though for extra cooling. Gord Schindler. MAAC6694

Reply to
Gord Schindler

snipped-for-privacy@aol.com (DanNJ) wrote in news: snipped-for-privacy@posting.google.com:

So . . . you had one dead-stick landing and the engine still seems to be working fine? As long as the engine doesn't make a habit of it, and as long as you're sure that you're not running too lean and cooking the engine, I'd say don't worry about it. These are glow engines, after all. As someone else has pointed out, "If lawnmowers used glow engines, everybody's lawns would be 4 feet high."

BTW - despite what some of the other posters said, I've had very good static thrust with an 11x4 on my .46FX, too. Actually, I usually run an APC 12.25x3.75. It seems to be a tad better for static thrust, although you'll never win a race with one.

Reply to
Mark Miller

Just keep in mind that an engine that is set too rich will usually not die, but will just run crappy. An engine that is set too lean will usually run hot and die. I would guess that the high temps. along with a lean setting caused your problem.

Reply to
CRAngelo

Well you asked for experts but I am going to reply anyway. I have heard many tales of people running big props on their 46 size engines, I have tried lots of props on mine and it pulls the best for what I want to do with the APC 11x4. I am located in Texas and we have plenty of

100+ heat in the summer too, never have had a cooling problem with this engine. So I think the 11x4 is a fine choice. Someone else has commented to the effect ...... one dead stick and you are worried ?? ...... I would immediately be concerned if my 46 deadsticked (just doesn't happen). If mine still has fuel and it deadsticks, the glow plug will fail completely in a few more flights. Its just the way this engine works. I run my engine slightly rich on the high end and it is extremely reliable. I would retune the engine and fly it cautiously for a couple of flights, if it deadsticks again or just doesn't run right I would put a new plug in it and see if that fixes it. For what it is worth I have a TT46 vs the OS46, but they are all basically the same.

Charlie

Reply to
Charlie H.

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.