Rookie question: nose over with BW's

[aeroaddict]

I started this thread because I saw a plane on it's nose that had big tires (on a taxi way). I'll confess that I'm a retired engineer and a thought occurred to me wondering if tire size has any effect on a possible nose over. It is a physics question, not how to fly/taxi a plane. And no I do not have 'legacy death gear' on my plane.

Great answers though.

[kestrel]

Last night I slept with my brothers sister in law and her husband managed to...

[Gordon Misch]

I'll confess that I'm a retired engineer and a thought occurred to me wondering if tire size has any effect on a possible nose over. It is a physics question

Haha! Well, Denny and 'slumber' kinda veered from that for a moment, didn't he? Good stuff - sent you a PM.

[cubdriver2]

I bet he was distracted after you slept with his wife?

Read again Dave

Glenn

[scout88305]

BW's aint your friend in certain soft or deep snow. Hard packed or frozen slush maybe. Lots of planes end up on their back when skis were essential for the mission.

[Litecub]

BW's aint your friend in certain soft or deep snow. Hard packed or frozen slush maybe. Lots of planes end up on their back when skis were essential for the mission.

This needs picture an explanation more than the above sentence. What is the back story here please?

[cubdriver2]

BW's aint your friend in certain soft or deep snow. Hard packed or frozen slush maybe. Lots of planes end up on their back when skis were essential for the mission.

I just saved this picture to my photo gallery. Anytime someone asks me if wheels are ok I'll send this and say " your choice "

Glenn

[cubflier]

Litecub,

That photo was from an earlier April 2009 thread and I think there may have been some discussion of events surrounding it. I remember there was a little photo shop variations that occurred but can't find the actual thread.



Jerry

[skywagon8a]

The amazing part of this picture is that the bush wheels are still there.

[scout88305]

https://backcountrypilot.org/forum/h...s-handle-20211

[frequent_flyer]

Don't forget fuel load. You have more chance of nosing over with half tanks than full tanks- the fuel sloshes froward adding to the momentum.

I agree that partial fuel could be an aggravating factor. Under hard braking all the fuel that would have been at the back of the tanks in 3 point attitude will move to the front of the tanks. This moves the CG forward and higher. There is also a brief impulse in the nose down couple as the fuel stop moving forward.

I wasted a few minutes yesterday creating this picture which shows how the CG moves with a change from small to large tires (CG position, red dot, is a WAG but absolute location doesn't influence the relative change):

[aeroaddict]

Nice.

I would offer the opinion that the distance between the CG and axle does not change, but the distance from the tire contact of the ground to CG does change with tire size. Implying the this is the true point of rotation: tire contact at the ground.

I should have better set parameters when first posting: constraints; same exact plane with 'magic brakes' that compensate for tire size. The only difference is the diameter of the tires.

Cheers

[bob turner]

It really does not take good brakes to lock up a wheel at low speed. Even a crummy cable operated brake will put a Champ on its nose if you jump on them at low speed. When the tail comes up, get off the brakes.

[aktango58]

Don't forget a little wind on the tail and a quick hit to the brakes- tail comes a bit up and you yank back allowing wind under the tail...

Yea, a little wind is a big deal!

[cubdriver2]

Don't forget a little wind on the tail and a quick hit to the brakes- tail comes a bit up and you yank back allowing wind under the tail...

Yea, a little wind is a big deal!

Stick back and make your own wind

Glenn