Too-Rigid Landing Gear?

I'm developing a little (25" span, 8-9 ounce) scale profile foamie Laird Solution. To make the landing gear look right I'm going to end up with an axle from wheel to wheel, which is going to make the whole landing gear fairly rigid from the axle to the hard points on the fuselage.

The fuselage construction is 6mm foam with 1/32" doublers back to the wing, to which the gear mounts.

My question is: does anyone on the group have any experience with using a really rigid landing gear, particularly on a foamie? Am I going to be ripping up the fuselage on landings, or am I just hyperventilating over trivialities?

This is a side view (sans wheel) of the 1/32" doubler and landing gear

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And this is a front view:

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Reply to
Tim Wescott
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On Wed, 29 Apr 2009 14:25:30 -0700, Tim Wescott wrote in :

Not me.

But I am interested in hearing how your experiment works out. :o)

I'm going to bet that the light weight will let you get away with it.

For big models, I've had some fun with bungie cords helping to provide some elasticity in the gear.

If you could put two small springs at each end of your horizontal axle, that would probably give you a greater margin of error for a heavy landing that a solid axle.

I know it may disrupt the looks a bit ...


Reply to
Martin X. Moleski, SJ

in :

I'm betting on that, too. The original did some amazing wing tip landings until I figured out that profile Solutions need lots more rudder to be stable in yaw (it refused to do anything but this really weird sideways crab; about 30% more vertical stab & rudder area fixed it right up).

It would be fairly easy to do the bungee thing; I'll do it if it seems to be an issue. But it's a foamie, fer crying out loud! I don't want it to get _too_ complicated. (And besides, the original had unsprung landing gear).

Reply to
Tim Wescott

I have not used rigid gear on a foamie. I like springy and light on a foamy. If it'll handle the weight try it. mk ps, the laird solution pics I just saw show a small area empennage, models usually need larger area (having deja vue)

Reply to

On the prototype the horizontal area is more than adequate, but the vertical area was way less than it needed. In a way it's nice that it happened -- the model was sort of a throw-away prototype* with too many problems to make it worth going on with anyway, so having the first dozen flights end in crashes wasn't as bad as it could have been, and now I know what to look for.

Interestingly enough, after I built the thing I saw an article in Flying Models on a bigger profile Solution; that one also needed increased tail area to fly well. Further, the general shape of the Laird Super Solution is practically identical to the Solution except for more streamlining and a significantly bigger rudder/stab -- so I think it may have been an issue with the Solution, Thompson trophy or no.

  • By the time it died it had scabbed-on mounting features for flying wires, a scabbed-on motor mount change, a scabbed-on reinforcement to the fuselage in the area where I _should_ have included landing gear mounts, no landing gear yet, and the honking big white vertical stabilizer extension that made it fly straight.
Reply to
Tim Wescott

Not quite a match for your question, but: The HobbyZone SuperCub, while not a profile plane, uses a fairly stiff wire landing gear that's anchored in the battery box assembly. The plane is famous for ripping the battery box and adjacent foam out even on moderate landings. rr

Reply to
tired bob

But still relevant and to the point, IMHO!

So it manages to yank a large bit of the structure of the plane out, not just bits of foam that aren't anchored in well enough?

Drat. I think I'm still going to build it as designed for starters, but I may purposely try various hard landings (I bet I don't have to work hard to achieve that...) just to make sure that nothing untoward happens.

Reply to
Tim Wescott

Good-sized chunks of fuselage often come out, but it is a weak area of the plane because the battery box displaces so much of what would otherwise be solid foam, leaving the anchorage inadequate.

You have a big advantage in lightness too -- the SuperCub is about 26 ounces, so you may well get better results. rr

Reply to
tired bob

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