"I think the 615s are rated for up to 12 lbs, and many of us consider that to be overly optimistic. I wouldn;t use them on anything over 10 lbs.

But, to make the most of the situation, I suggest starting out by beefing up set screws and making sure they have a flat surface to set against (not too much tho, you don't want to grind away all the strength, just enough for a small flat spot). By beefing up, I mean using bigger set screws if you can. I think they come with 4-40s? I any event, all mine are 6-32s, AND I use regular allen head and/ or button head (allen) screws instead of set screws where room/ clearance permits. These allow me to apply more tightening torque than with headless set screws. I also drill and tap more holes if possible.

Some of the early 615s had 5/32"diameter struts, but for the past several years only the 3/16"diameter versions have been manufactured. If you have the 5/32"versions, then it is possible to drill out the trunnions and gears to accept the 3/16 struts, OR you can order them from Robart, along with the 3/16"struts. I have never heard of using even larger struts with the 615s, but I suppose it is possible. Again tho, I think 3/16" s getting a little flimsy for aircraft in the 13# range. I guess my question would be: WHY is it nosing over? Is it because the struts are rotating, or because they are flexing so much as to move the wheels back (as I have seen the H-9 Mustangs do), or because the grass is too tall? I fly off of grass all the time, and now that my retract problems have been solved for the most part, nose overs are very rare except when I fly from a field with tall grass.

On RoboStruts: they will help prevent flexing, BUT will increase the chances of the strut becoming bent to the point where disassembly and straightening is required.

On wheel size, MOST ARFS come with wheels that are too small, and taller wheels do navigate tru grass easier, so I would suggest trying a larger (but light weight) set. To give some perspective, the scale correct size for a 62"span Corsair is 4". tho I don't recommend that size for the Top Flites, I would recommend that size for your's which I believe is about 75"span? Dave Brown makes some light weight wheels in that size.

Hope this helps, and good luck.

Also, getting back to strut wires: a suppose another possiblity is using 3/16" daimeter titanium struts. I have never used these, but as I understand it they are lighter, yet more bend resistant than the steel ones that come with our retracts. I think these are availble from Central Hobbies? "

BTW, my recommended size for the main wheels on a Top Flight 1/8 scale Corsair is 3 1/2" ~ 3 3/4"