Wheel Spacing

[Mike Griffin]

When converting a model that calls for a fuselage mounted landing gear to a wing mounted gear, is there any rule of thumb to how far apart the wheels should be? Does the wingspan play a part in the spacing?

Thank you
Mike

[Ken Culbertson]

When converting a model that calls for a fuselage mounted landing gear to a wing mounted gear, is there any rule of thumb to how far apart the wheels should be? Does the wingspan play a part in the spacing?

Thank you
Mike

I think that is really personal preference, but I use 1/3 of the span +- about an inch.  I make my outboard strut 1/8" shorter to make the takeoff and landing 2 wheels touching.

Ken

[Tim Wescott]

When converting a model that calls for a fuselage mounted landing gear to a wing mounted gear, is there any rule of thumb to how far apart the wheels should be? Does the wingspan play a part in the spacing?

Thank you
Mike

If wingspan played no part in the spacing, then Piper Cubs would have wheels spaced 4" apart, or 1/2-A planes would have wheels spaced six feet apart.  I won't even get into suppositions about B-36 landing gear in this context.

I'm thinking that if I were really concerned with this I'd make a test wing with several different landing gear mounts, and try everything from wingtip mount to bicycle gear.  I suspect I'd find out that a too-narrow gear is susceptible to the plane rocking on landing, or dragging the outer wingtip, while too-wide gear (A) looks odd, and (B) is susceptible to untoward yaw as one wheel or the other gets too much grip on the tarmac or grass.  Ultimately it would boil down to personal preference, a dose of what you tend to fly off of, and whatever works for folks around you.

[Steve Helmick]

Wider is good, but depends on how strong the structure and how rough the field. IMO having the OB wheel touch first improves the landing significantly. Why? The rebound is only 50%.  Steve

[Dan McEntee]

   Wing mounted gear that is too wide adds to the bar bell affect in the roll axis, so don't over due it there. Too narrow and it will rock a lot on rougher fields. I just rely on the designer or my eyeball and the age old LARs method of what "Looks About Right" . Having them positioned correctly for and aft is more important, I think.
  Type at you later,
  Dan McEntee