Prop and Tire Question

[perryv1]

Re: Prop and Tire Question

I have a 7442 prop on my plane and with the 85 hp it would turn about 2350 static. With the 0-200 conversion it turns about 2450. Boy that extra 100 rpm Really makes a difference.I can get cruse speeds of around 105 @ 2400 on wheels and about 95 on floats at the same rpm.
I agree that the one leading in a formation seems to be the faster plane,Unless its a CUB.LOL
I have always run about 15 PSI in my tires, seems to be a happy medium.

[Dusty]

Re: Prop and Tire Question

Where's this thread been hiding?

I'm running a 74/40 on a C-90 on the Tcart. It's about perfect. 74/38 on a 90HP Champ is a little flat - you really have to watch it to keep it under redline, and it's SLOW.

Longer props are ALWAYS better for takeoff. Just flatten it out till it turns what it should.

What's stamped on the face doesn't always have a lot of relation to what's actually happening, even with a new prop. It's not that expensive to get it checked out and repitched if necessary.

It's impossible to recommend a tire pressure without knowing the size. I've run 8.50s around 8PSI in fairly rough stuff and not damaged a wheel, but you can't get on the brakes at all. I ran the Goodyears around 12, which is WAY too much, but I had trouble slipping valve stems at anything less. I have a set of 25" airwheels(??) on the Tcart that I run at around 8 - they're a bit cracked and I don't want to flex them much, and I try to avoid taking that airplane anywhere very rough anyway. I run 31" Bushwheels at 3PSI on the Champ (4 if I'm going anywhere with steep sidehills). They're a little squirrely, but nothing unmanageable. They'll definitely get your attention on pavement with a 20MPH crosswind.

jgerard: I considered the same thing. I believe the trick is adhesive or screws to hold the beads in place. I bet you'd have trouble sealing the wheel up - silicone, maybe???? Experimental guys can take a LOT of rubber off as well - those tires are WAY too thick for light planes. I finally bucked up for the Bushwheels. I wish I wouldn't have waited so long - there's WAY more difference between Goodyears and Bushwheels than 8.50s and Goodyears. They are worth the $$$.

Paint a stripe across your tire/wheel if you're running lower pressures. No need to dismount if they turn a bit - just let most of the air out, get someone to push you backwards, and JAM on the brake. You can do it by yourself using the park brake, but it's not much fun.