bush plane landing gear

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reubenT

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I've done a bunch of watching off airport landings of small planes on u-tube and been thinkin. Has anyone invented a way to have both big wheel landing gear and floats? The only wheels I see combined with floats are little bitty things only good for paved runways. (and an occasional pilot forgetting to retract them and flipping the plane on water.) I know there would be extra drag and extra weight to deal with. I've been dreaming of possible ways to put both on and have one or both systems retractable with air pressure/vacuum cylinders which would also serve as air suspension shock adsorption. Something like wheels that would fold back and fit into aerodynamic boxes, or floats that are inflatable with a partial aluminum housing that would flatten and fold up against the fuselage. Might help with drag but not weight. Although the air cylinders would replace steel spring suspension. With someone doing a lot of back country flying it would be very handy to have a choice of either kind of landing gear.
 
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Himat

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If you search aviation history you will find that airplanes have been fited with all kinds of undercarriage. Wheels, skis, floats, catepilar tracks and air cushion devices. Quite a few combinations thereof also. An early one was the Hoeningstad Polar, a flying boat with retractable wheels and skis. Big wheels and floats ar probably possible to combine, someone might have done it, but it couldt be difficult to trace down. The reason is that it's a rather small niche.
 

reubenT

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OK! guess it's up to my imagination to make something, It would be a challenge to make it light, strong and aerodynamic.
 

Battson

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Float's weight is a challenge on it's own, you need more room to take-off compared to wheels. Bush wheels are also heavy, maybe 25kg more than regular wheels. But you use bush wheels to get in and out of smaller unimproved areas where delicate parts cannot roll over the ground.
To make a bushwheel-float retraction system strong enough to roll over very rough ground at >80km/h (minimum takeoff speed for a heavy plane) would be heavy by any standards, let alone small aircraft standards.

The objectives of the two are incompatible in my view, and even if there were some market for it, the weight would limit the ability of the aircraft to ever fly.
The solution you are looking for in this case is a helicopter.
 

bmcj

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The big balloon tires will allow you to hydroplane across the water at a faily low speed (below stall speed). Bush pilots use that technique to utilize the water as part of the runway, rolling up onto a beach or sand bar at the end of their run.

I don't know if this would work for you, but maybe there's a way to put a float hull higher than the wheels so that as the plane slows below hydroplane speed and the tires sink, it would come to rest on the float hull. The biggest trap I see here is on takeoff, trying to get up to hydroplane speed with the tires partially submerged. For this to work (if possible), you would want the float hull as low as possible without dragging on the ground during land ops AND without allowing the prop to hit the water.
 

BBerson

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Cubs with big tires flip over in soft snow. The same will happen in water. Yes they will hydroplane above 30 mph.
How do you get from zero to 30mph without flipping?
 

reubenT

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Perhaps an enlarged version of what is already in existence would be practical, instead of little bitty wheels that drop out of the floats, large diameter ones on pivoting arms that store inside the floats. Would require a float built to fit them, with either a water tight cover under them, or more likely a cover with hole that would shed the water from the wheel well with forward speed. (since a "water tight" cover is likely to leak, and then retain the water when departing) and they would extend above the float when retracted. Front wheel could fold back, air cylinders operating them. A little pressure/vacuum pump and lines would be easy enough to add, and the cylinders can be had in aluminum. I have a few I picked up from a scrap yard but they may be too small. Then again a 2" cylinder with 125 psi will exert nearly 400 lb, with more weight capacity as it depresses. That might be enough. Oh well, something to play with eventually.
 

autoreply

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Close the top of the floats with a ultralight composite cover. Make folding rubber covers for the front and rear of the floats and either rig a separate blower, or make a big inlet behind the prop.

A flying hovercraft must be the ultimate ATV.
 

bmcj

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Cubs with big tires flip over in soft snow. The same will happen in water. Yes they will hydroplane above 30 mph.
How do you get from zero to 30mph without flipping?
I wasn't sure if there was a way to be on the floats before the wheels sink too far into the water (i.e. - the float hull just above the the bottom of the wheels, kind of like snow skis work with the wheels just peeking through the ski).
 
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BBerson

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I wasn't sure if there was a way to be on the floats before the wheels sink too far into the water (i.e. - the float hull just above the the bottom of the wheels, kind of like snow skis work with the wheels just peaking through the ski).
Might work, I don't know.
I do know that model airplanes have used very thin fixed water penetrating wheels. ( wheels made of thin plexiglass)
I think 1" wide penetrating wheels ( full scale) would work. Sort of like a sailboat daggerboard.
 

cluttonfred

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Perhaps the easiest solution is not to use floats at all, but retractable gear on a boat-hull amphibian. You can see from something like a Volmer Sportsman that it would not be too hard to fit balloon tires with modest modifications such as extended axles and reinforced gear legs and mounting points. You might even be able to include fairings to reduce the drag penalty of those big tires.

vj-22.JPG
 

Holden

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I've done a bunch of watching off airport landings of small planes on u-tube and been thinkin. Has anyone invented a way to have both big wheel landing gear and floats? The only wheels I see combined with floats are little bitty things only good for paved runways. (and an occasional pilot forgetting to retract them and flipping the plane on water.) I know there would be extra drag and extra weight to deal with. I've been dreaming of possible ways to put both on and have one or both systems retractable with air pressure/vacuum cylinders which would also serve as air suspension shock adsorption. Something like wheels that would fold back and fit into aerodynamic boxes, or floats that are inflatable with a partial aluminum housing that would flatten and fold up against the fuselage. Might help with drag but not weight. Although the air cylinders would replace steel spring suspension. With someone doing a lot of back country flying it would be very handy to have a choice of either kind of landing gear.
Reuben,

I am going to use motorcycle wheels 24-26 inch in diameter with air tight side walls that give flotation. The tires goes in floats, and the floats are steerable with the rudder pedals. Hydraulic shocks connect to the set and air is at the end for cushioning. Dampening is via a check valve and metering. Low weight and 3 ft of stroke...

Holden
 

Dan Thomas

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Wheels in water offer terrible drag. Those big bushwheels will indeed hydroplane at speed but get a little slow and the water climbs the backside of the tire and creates a really strong downward "lifting" force. Any one (like me) that has towed an inflated inner tube behind a boat knows the amount of power it takes to get it up on plane.

Then there's that video of the 185 on amphibs landing on the water wheels-down...

https://www.youtube.com/watch?v=NBkzh0LKe5I

Just that bit of drag from the main wheels started it all.

Dan
 

Holden

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Wheels in water offer terrible drag. Those big bushwheels will indeed hydroplane at speed but get a little slow and the water climbs the backside of the tire and creates a really strong downward "lifting" force. Any one (like me) that has towed an inflated inner tube behind a boat knows the amount of power it takes to get it up on plane.

Then there's that video of the 185 on amphibs landing on the water wheels-down...

https://www.youtube.com/watch?v=NBkzh0LKe5I

Just that bit of drag from the main wheels started it all.

Dan

Dan,

Yes, wheels suck down, but not if there is a ski in front and/or behind. I am looking to use the wheel as a way to deflect debris in the water. If a ski deflects the water down or to the sides to miss the tire, then the tire can stick down some and not drag. This way you get best of both worlds.

Clearly a wheel by itself without something forward will not work. The idea is to be able to skim the water yet also be able to ride on the sand or rocks when the water turns to puddles. Rivers have this water/land mixing and to be able to land in the mix is the idea.

When the mix is solved, so is the problem of forgetting to put the gear up or down as shown in the 185 video.

Either up or down, a crash should not occur. Minor damage or scratches on a ski bottom would be OK if the gear were not positioned correctly, but not a flip over or crash.

Holden
 
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