Ah, but you are describing the gear as longer not taller. The advantage comes from moving the axles forward not from moving the airplane higher above the axles. The forward advantage remains in level flight attitude. The taller part is a disadvantage in level flight attitude.Originally Posted by KevinJ
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If you operate in a handful of inches of snow, the taller the tires the easier it is to move the plane through it. 3-4” of crusty snow is no big deal on 31s and is no cause for concern on 35s. Like with any soft or sticky surface you need to be ready to add power. Taller gear isn’t much of a factor in that. Brakes are a total non factor since they’re completely ineffective. The drag of the snow will stop you faster than you want. Power counters the deceleration.
Power, actually thrust, increases the couple tending to nose the airplane over. If power helps prevent nose over I assume it is because of propwash over a raised elevator.
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Rapid deceleration is the problem. Controlling deceleration is the solution.
Take a tall object with a small base. Make it move horizontally toward an obstruction that impacts the object at its base. The base of the tall object decelerates but the CG of the tall object wants to keep going forward so the tall object rotates about its base.
You suggest that pulling forward on the tall object above its base will reduce it's tendency to tip over. Clearly that does not stand up to any scrutiny. A force pulling forward is only useful if it acts in the same plane as the obstruction causing the deceleration. Only then does the forward force counter the deceleration without producing a rotational couple.
Power only helps if the downforce on the tail produces a couple that is greater than the thrust couple.
You don’t fly on soft surfaces much, right? When you do try it? The proper response to uncommanded rapid deceleration is to apply power and control the deceleration. It’s the only tool you’ll have.
The 172 pilot should have been using classic soft field technique that all of us were taught in nose draggers. Maintain power to keep the nose wheel up. The more the plane decelerates the more power it takes to make it work.
Is it the uncommanded rapid acceleration you want to oppose or is it the resulting nose over tendency?
How much would you expect adding power to help in an aircraft with a high thrust line and/or the elevator out of the propwash?
I could be wrong, but. The attitude of aircraft should not matter when it comes to prop wash over the wing/tail. If it did aerobatic flight might be difficult. The downforce should be the same tail low/level flight/tail high. You can hold a tail down, or pick it up with power and elevator. Wing AOA, CG, Stabilizer position and flap position also matters. The problem with landing in snow/mud/water/sand/ect is overcoming the drag created on the tires. Forcibly holding the tail down in snow/mud/water/sand is going to drive the mains deeper into whatever stuff stuff have. Once you reach the drag point to overcome the tail downforce that forward force the prop is creating will become a huge problem. If you fly the tail and keep it from digging in you have now removed some of the downforce. The force momentum created by sudden drag is another issue if you are unprepared. Bottom line is I think the power helps until it doesn't, then it hurts. The smart guys should be able to do some of that triangle math to help figure out at what point the long gear hurts vs helps. I put my skis on this weekend.
DENNY
Air pressure?? With my very limited experience flying Bushwheels on snow, I did notice that when I had low tire pressure, 6psi, the snow would build in front of the tires like a tire chalk and the tires did not like to roll. When I ran higher pressure they penetrated the snow and rolled better. Can anyone with more experience speak to this? Thanks
If anyone wants to run an experiment to test what snow conditions will cause a Bushwheel equipped aircraft to flop on it's back, and at what specific tire pressures, I'd love to hear about it. But I believe that Doc Denny was trying to make the point to NOT intentionally land/take off on wheels in snow. If you have been forced to do this, please share with us what worked or didn't work for your specific case.
Web
Life's tough . . . wear a cup.
Sometimes in the Spring after lake ice is bared in spots I put on tires and go land to camp. Taxiing over remaining soft drifts (I'd guess >6" thick) between bare spots can stop the plane or at least grab a tire. Avoid them especially later in the day as the air warms. Then sometimes it decides to snow again in late April or early May. Plane on tires should pack the snow by slow taxing a proven marked path before takeoff. Use a shovel and snowshoes if needed. Melted water collects in low spots on the ice until it drains off through cracks and small holes and the ice floats up some and drys. Water if unfrozen on top can only slow the plane if not too deep. Like landing on snow make a few light touch passes with power and tail low to feel for drag and pack a safer strip with the tires.
Gary
what ever set up you have and you know you have to go in and out in snow or soft conditions put weight in the tail lots
Dang,, tough crowd, I understood the point of the thread and was hoping to learn from some with more experience. I run wheel skis, so spring season is not really an issue for me. Late season moose camp and getting dumped on while out or having to recover friends still out. Too rough and short for skis and in my case I had boots of the ground with an accurate measurement. Tire pressure observation was a result from almost ending up in the oops thread at said moose camp, not to be out playing in the snow. In my very short 3 seasons of ski flying,, one thing I've learned for sure, that is snow changes quickly. This site has an extreme amount of experience, but man questions and comments often receive hash responses. Merry Christmas Sir.
Merry Christmas
Web
Life's tough . . . wear a cup.
Treat it like a carrier landing, touch down with full power and full aft stick, if it feels ok back off power and stop. If not, keep in full power till you stop. If you lock your brakes you can potentially build a pile of snow in front of your tires that will eventually get too big to continue pushing and too big to roll over, no bueno and likely earn you a hat.
If you’ve managed to stop upright, your next concern will be packing out a runway to depart.
in Southern California it occasionally snows but not often enough to carry snowshoes.
Also, If you’ve ever engaged in the sport of “inner tubing” in snow you’ll have a pretty good idea how bushwheels behave side hilling on snow. Pack your runway on the “fall line” if uneven slope.
Better still, don’t land on snow with bushwheels.
Well said Oliver -- I like how he puts it -- like an inner tube is how control-able a bush wheel is in snow. Now let the air out down to 3-4 psi and its not round anymore its flat on the bottom slow but packs a nice track and goes straight. This is not for landing in bad snow conditions this is a method to get out of jail free after you messed up landing there in the first place. Who cares about 2-3 inches I am talking really messed up. Now if thrust would overcome the tail down force under full power we would flip every taildragger over anytime we do a full power static run up - so give your head a shake full power will always save your ass unless you are too slow to apply it. Again Oliver has it right
This type of flying is more Art than anything, but Physics are still the foundation of it. No wild ass guesses can save your Butt but a good understanding of physics can.
I hope this post does not do more harm than good -- Oliver did a good job at putting it straight the way is, anyone that has stoped in less than 100 feet under full power right side up will understand.
Like a young friend this spring he buried his Citabria on 31s to the axle on a sand bar that was not so sandy (River silt) sucked him in under full power no flip over. Now the same guy did flip over 4 years prior by cutting the power he learned this time the Helicopter ride was much cheaper the plane unharmed. If anything good comes out of this tread I hope we can get this point across.
Land where you can afford to loose it? I never could so didn't.
Gary
Lots of days guys go flying before plows go plowing. Common at the airports I’ve based at. Usually easier than those same airports with glazed ice on a warm day. Talk about slick. Given that most strips are crowned to promote drainage the narrower the strip the scarier lack of traction can be. With snow and ice whether on tires or skis your turning power is in the rudder, but throttling up to blow the tail can cause serious pucker factor when there isn’t much space. Good times.
In two weeks, my tracked battery powered (72 volts) snow bike will arrive. Part of my excuse for buying it is to use it to pack a path down my sloped runway. I think it's track width will be more less equeal to the width of the Datum's, so a run down and back up should do it. If I get the spread wrong, at least one ski will be on semi packed snow. I've never wanted a snow machine, but some reason a snow bike pushed my buttons, lighter for one. Narrower too, that will help in the trees also. I've ridden enough ebikes (got 3 of them) and my electric dirt bike (Sur Ron) to know the disadvantages and the advantages of an electric platform. Mike Patey needs to get two of these to hang on Scrappy, when he get's his wheel skis on it. https://youtube.com/shorts/ygVnymyJG-4?feature=share
A piece of chain link fencing makes a good snow drag. Either by itself, framed in on all edges with steel fence pipe, or fastened to a flat platform made of plywood reinforced with lumber and weighted down with more snow on top. All it takes is some disturbance of the soft snow to make it harden. If snow moguls form the chain fencing will cut off the tops if weighted down. The fencing will try to angle sideways unless pulled perpendicular to the cross links. Making and maintaining winter runways is always fun.
Gary
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