Just a quick questions on the landing gear wheel position relieve to wing leading edge. In stunt we have it straight down for grass or back some for pavement. For Rat style ships going over grass do they have them up under the engine or even ahead of it? Photos would be appreciated.

Best,   DennisT

In the old days the wheels were usually just behind the prop.  Some were even ahead of the prop.   

For pavement, a shallower angle may be used in order to facilitate pulling the plane into the pit.

For flying of grass with these types of ships one of the concerns is having the prop and lines survive the landing. Yes I know APC props can take a lot of banging around but there are better prop choices that are less sturdy (wood, some thin glass). Our field is a grass soccer field with nicely mowed surface but still not like pavement. For Stunt 1 3/4" wheels get off and down nicely. I'm wondering with this style ship (rat, FOX35) does the more forward wheel position give a more survivable landing without the ship flipping end over end?

Best,   DennisT

Dennis,

The correct reference is the wheel contact point on the ground relative to the aircraft CG. The default position for conventional gear is 15 deg ahead of the CG.

The attached scan is from the 1949 NAA rules for 190 cubic inch class racing airplanes (aka Goodyear racers)

Bob,

The drawing you showed is excellent.  Bill Netzeband showed similar drawings in several of his columns over the years and also in his 5-month long series on how to design and fly stunt ships in the mid 1950's.  That same 15^o angle from the CG applies pretty much to all full size, conventional gear aircraft.  One thing to note is the 15_o puts the point of contact of the wheels on the ground, not through the axles of the wheels.  Not that it makes that much difference for our models, but for relatively larger diameter wheels, it starts to make a difference.  Also what needs to be considered is the measurement is from the aircraft CG including consideration of its vertical CG.

Keith

Here is the sort of plane we raced in the 1960's. The Royal Rodent set-up was very similar. Forget the science. This worked anywhere. Go fly your model.

Here is the sort of plane we raced in the 1960's. The Royal Rodent set-up was very similar. Forget the science. This worked anywhere. Go fly your model.

Yup

Ken