skeeter_ca

I replaced my old K&B 40 with a OS 46ax. That means i went from a 10" prop to a 11" prop. I replaced the tires from 2 1/2" to 3". Now i only have 1 1/4" ground clearance. Is this considered adequate clearance for a trainer. I know i still need to get better at landing and stop bouncing but i keep knicking the prop. 20 years ago when i flew it with the K&B i never hit the prop, not once. I am also wondering if i need more negative incidence in the wing. I don't have an incidence meter yet. When i do a good smooth landing the plane seems almost level. It is not nose high. When i slow it down to what looks like a good flare it seems to stall and hit the runway hard, bounce and knick the prop.

What do you guys think?

da Rock

If you're knicking the prop on landing, then it doesn't matter what the clearance measures, it's not enough for the landings you're going. If you're flying off of pavement, it's not odd to knick props. But you didn't mention the trainer. It must be a taildragger, so stop trying for a three point landing. That'll give you some time to get used to controlling your landing speed better and once you've got that down pat, you can go back to working on getting the flare right.

BTW, don't work so hard on the flare. When the airplane is about to touch down on the mains, just pull off the remaining throttle.

One thing to look at closely is how your landing gear is working. Has it spread out? Most trainers' gear can be bent somewhat. Try bending the gear in some. You'll bet more clearance AND a bit more stiffness. Sounds like you could use stiffer gear. And taller gear is probably available at your LHS.

skeeter_ca

It's a trike gear trainer. Great Planes Trainer 40, from along time ago. Guess i'll check for a possible stiffer gear and work on smoother landings. I'll check my old plans and see if i have the correct incidence on the wing.

Desertlakesflying

My Feedback: (28)

Why an 11 on a 46 AX? A 10X7 or 10X6 works great. They are also flown with as small as 9.5X7 in pylon races. An 11 just slows that engine way down and heats it way up.

Zippi

My Feedback: (10)

skeeter_ca,

If this trainer is a trike gear and your hitting the prop on landing, your probably not landing correct. Get with one of your instructors and have them show you the proper way. It's a prime example of cutting the throttle way to soon and trying to let the plane float in and it's more or less just flopping down on the runway and not making a correct landing. That's why the prop it always hitting the ground. There is some good pointers in what the other guys said. Keep a little of the throttle on until your over the runway and try for a little faster smoother landing and not a belly flop.

da Rock

Don't sweat the wing incidence. It sounds like you're stalling the plane and dropping it hard. That'd happen no matter what the incidence. It's the AOA that stalls the wing, and the wing is free to reach a stall AOA no matter what angle the fuselage or stab is to it.

We've got a couple of guys at the field who refuse to let their models come on in. Both of them basically slow at least one landing a day until the airplane stops flying. It's usually the last flight of the day for that airplane. They've heard it over and over that they just need to leave a couple mph on the plane and the suckers wouldn't thump down, but they just can't seem to do let the airplane keep any speed and come on in.

Every airplane has a safe, lowest landing speed. If the airplane stalls on landing, it was slowed down more than that safe, lowest speed.

da Rock

BTW, the guys at our field who run OS46AXs have gone to 11x6s for most airplanes. And I'm running 11.5x6s on most of mine. The engine is a bull. It'll run a 12x6 on a couple of my smaller birds, but the vertical suffers on the regular sized planes, meaning that's too much prop. I like as much fan (diameter) as possible, so tried a cutdown 12x6 one day. Took the balancer to the field and took 1/4" off each test. At 11.25" that particular 46AX had just started showing a bit of loss on vertical, so I figured to save that prop for winter flying (air is denser) and made up some 11.5s I was trying some 12x5s but although the vertical was excellent, I didn't like the obvious loss of speed that was accompanied by obviously higher rpm. No value in that.

skeeter_ca

Thanks guys, I'll try to bring her in a little faster and let her settle on her own rather than force a slower speed and end up belly flopping.