Tire pressures on the M4 180V

[Tapiola]

I recenty got my M4-180V and have done two extensive x-countries and many practice circuits and am starting to feel at home. A step up form my PA-22 taildragger! I have read all about the techniques in this forum for landing this baby, particularly from Jeremy which I found very useful, but I still manage to bounce quite often. Would letting some air out of the 8.50 tyres help? I presently have 20 lbs in the mains. What is the recommended psi? Thanks, Chris.

[maules.com]

Generally speaking, set tyre pressure so that the outer edge of outer groove is just touching the surface.
If you are bouncing, your touchdown is a little fast and the wings have not yet finished flying, if attempting 3 point. try holding the mains off just a tad longer. i.e. land 6inch above the runway and gravity will take care of the rest.

[Tapiola]

Hey Jeremy, thanks for the tip on the tyres. Will check on that tomorrow. I have greased on a few landings but not quite sure why!! I am certainly not too fast as my stall warning sounds 50% of landings. A GREAT Aircraft!! Too bad you are so bloody far away.........would love to got up wid yer for an hour or so!! Thanx, Chris.

[maules.com]

Chris, the stall warning can easily be totally off. If perfectly set it goes off 7mph before aproximate stall speed.
Take the plane up and do a couple power off stalls to see if the warning goes off at the right time, then try again with about 100rpm added. That will give you a ball park reading.
Now try again rotating the plane as if flaring to land from your normal VSI over the fence speed and ASI speed.

[Tapiola]

OK good point!! One just assumes the stall warning is set correctly especially on a practically brand new aircraft!! I did do a coupla stalls when I first got her but didn't notice the airspeed. Will get up there & check it out!! Chris.

[TomD]

One just assumes the stall warning is set correctly

You know the old saw about assume? It makes an ass of you and me.

The stall warning on my M5 is a pretty little light that lets me know the electrical system is still working.

Just kidding, it does make me look at my airspeed, attitude and coordination to make sure I am not doing something more stupid than usual.

TD

[Duane]

Just as a btw.. 8.50's leave the factory at 18 psi. However, real world experience is probably more accurate in what is best.

[andy]

You might be flaring a little too high and coming down too hard when the wing stops flying. A gradual flare from flying level about a foot above the runway with power idle to the 3-point at-rest attitude should work. I don't think tire pressure has that much to do with bouncing unless they are way over pressure. I keep 26 PSI in my Goodyear 8.50x6 tires, which lifts the outermost groove off the pavement at normal weight. I use the feel of the airplane controls more than the stall warning light to determine how close I am to a stall.

[aero101]

I once heard another instructor say- "See how LONG you can land", another words get that 3 pt landing attitude and hold it 12" off the ground as long as you possibly can, maybe even a touch of power, don't anticipate wheels touching, and this will generally give you the best landings!!! Tire pressure has got little to do with it unless way off..... My stall warning pretty much means that the battery is charged, use that seat of the pants and flight control feel..

[iceman]

I have my 800x6's at 26 lbs... and switched to my M4 10 years ago from my tripacer. I still bounce one every now and then and I harken back to my instructors words... fly a shitty pattern and approach and you'll have a shitty landing. When i think back over my approach when I bounce I can usually pin point it to having to make more corrections than usual during my approach...which means i did a shitty job..and more often than not it's because I was too fast at touchdown , which is exactly what Jeremy said. my best landings come after I've been practicing a month before I go to Johnson Creek, trying to get as slow and on the spot as I can for those dirt short strips. So keep practicing...

[Tapiola]

Ok I took your advise Jeremy, did a stall at 3000ft; multiplied the number by 1.3 and got 58.5. I approached at 55/60, flew it down the runway a bit at 1700rpm and greased it on. Didn't even feel the wheels touch! Now I just have to work on my touchdown point. Many thanks. Chris.

[Tapiola]

Thanx to all you guys out there; Andy. Aero101, Iceman, Duane & TomD. I checked my tyres B4 I took off and had 16psi. Pretty close!! Just as I thought I felt the wheels touch my stall warning went off.....so I know it works and my battery is charged!! Thanx a bucnh guys. Chris.

[Layne]

Sounds like you have it.
If you really want smooth touchdowns try the bush wheels next. Definetely if you are on grass or unimproved. They make for great single point landings.

[maules.com]

Chris, Now, about 1100rpm (no exhaust popping) set up a steeper approach aimed 50 to 100ft before desired touchdown point, so a dab of power carries you to it if needed. Your flare should get you 6" or a foot above ground then when you know you don't need more throttle, release the flaps to -7, (but DON'T roll the yoke while dropping flap lever).
Brakes on yoke full back and you're done.
Your aim point should be a 2 foot wide x 10 ft box into which you intend to put the left main

[Tapiola]

Jeremy: I HAVE been dumping the flaps after the wheels touch but my right arm is not ape-like so I lose sight-o-the runway for an instant!! I can only reach 0 degrees without genuflecting!! If I didn't have inertia belts I doubt I would be able to do that!! I wonder what the local strip would say if I painted a 2ft x 10ft box on the runway!! Thanks Chris.