Bicycle landing gear

[Weaver]

A principle reason for adopting "twin-tandem main wheel" tandem gear, as opposed to "single-track main and nose", is bomb bays. On the Yak-25, which was a fighter, there was no bomb bay, so they put a single main gear unit on the centreline, just behind the CofG, combined with a conventional nosewheel. The weight distribution was the same as a normal aircraft, i.e. mostly on the main gear. On the Yak-28 (which started out as a bomber), they wanted a bomb bay around the CofG, so they had to put two, pretty much equal size units ahead of and behind it. The weight distribution in this case was more like a B-52, i.e. 50/50 between the two main units.

By and large, if you must have single-track gear, then main-plus-nose is better, since the fuselage only has to take the main stress near the CofG, which is where it's likely to be strong anyway. If you have twin-tandem main wheels fore and aft of a bomb bay, then the fuselage has to take significant stress towards either end, which is not helped by the big cutout amidships for the bomb bay doors. Accounting for all this adds significant structural weight.

[The Rat]

I contest that sailplanes don't have flaps though, many high performance sailplanes do have them, ...

Never saw any when I was gliding, but that was 35 years ago. Is nothing sacred? 

[PR19_Kit]

....By and large, if you must have single-track gear.....

This is a Whiff I'm building, I mustn't have anything at all....... 

The donor aircraft started life as a bomber, and it's stretched too, so I may go the dual-main route if I decide to stick with the bicycle gear. Either that or put them out on the wings in a standard trike config.

[Geoff]

The Yak-50 experimental fighter also had a bicycle u/c with a twin wheel main unit somewhere around the wing trailing edge and a small single wheel front wheel and two small outriggers. It looks very similar to the Yak-25 twin engined fighter.