by Zach Grant L1011jock » Mon Jan 04, 2010 4:31 am
Tim,
2800' of smooth grass is not a problem for a twinco that is not loaded up to max gross (as long as the ends are relatively clear). The landing gear is stout, and should do just fine on the grass (just stay ahead of things. Check regularly for anything getting loose, and fix it immediately. The rougher the surface the more things are going to wear). The one caution is that if there are many ruts or other mounds etc other than smooth rolling type, the props only have a nominal 11" tip clearance if the struts are all extended at 2.75". Any further extension of the mains or compression of the nose and you loose clearance quickly (keep the big nose tire for sure). This is not a problem, just something to consider. It does sound as if you can benefit from a Robertson modified bird. Everyone calls these STOL kits, but Robertson is quick to point out they are "high lift kits". They do not claim to decrease stall speed, just make it safer to fly closer to the stall, and they do have more drag for a steeper approach with less float, but you still need to be on speed.
The twinco likes to be light. For that reason, I would suggest looking for an earlier model year (63/64) non turbo, and not a Miller. The Miller adds significantly to the empty weight, and although the performance in climb is very nice, it doesn't have the light weight numbers the straight PA-30 has. I have owned an early ('63) PA-30 normally aspirated with tip tanks and no other real mod, flown lots of others, and currently partner in a '67 turbo C/R robertson with alky props, LoPresti Cowls, gap seals, heavy duty brakes,...on and on. The normally aspirated '63 twin was some 400+ pounds lighter empty weight than the '67 (both were weighed, not calculated). It was noticably easier to move around on the ground (though it still liked its power tow), but that lower empty weight translated into some pretty amazing numbers. Solo with almost full tanks (120 gal with the tips) landing and T/O distances were easy in the 1st 800' of one of the local airports runways (only turnoff without backtaxiing before the full length parallel was built). With 5 kts or better of headwind down the runway, only light brakeing was necessary.
I hope this gives you a bit to chew on. PA-30's are great airplanes, but for your mission, I hate to say it, the RV7 might be a better fit. Feel free to PM me with any questions. I am one of the ICS technical advisors, as well as the Comanche Flyer Foundation Director of Training.
Zach
"Keep it above 5 feet and don't do nuthin dumb!"