if you want to use only 3 gyros, you will have to use onboard mixing, here's why. a vtail mixer splits the signal into two other signals. the master + the input of the slave, and the master - the imput from the slave. if you want an aileron gyro to affect both motors, you have to put it in-between the receiver and the aileron (for example) input of the mixer. if you are shooting for under 1 lb, you may not be able to do it with off the shelf electronics. you may have to design and build your own circuitboard to eliminate all the weight of wires and packaging etc. also, if you are shooting for under 1 lb i would use the model's torque to control rudder instead of tilt the rotors as that will weigh considerably more especially including the gyros. if you use onboard the setup will be much simpler and cheaper as you will most likely have to custom manufacture the gimbals yourself. i would use the 6 mixes to reduce the throw (the minimum of 30% on most radios is way too much) and to be able to raise the rates on the flip of a preferably spring loaded switch in case of an emergency. to reduce the throw i have a set of mixers mixing both the aileron and elevator channels to themselves with a value of -70% both ways giving me (along with the already decreased rates) about 9% travel and it will take 2 mixers for that. whel i flip up the switch those turn off and another set turns on that mixes them onto themself at a rate of -60% to give me a bit more travel in case of gusty winds or something happens to one of the motors. that will take another 4 mixers. if you want to put a gyro on the urdder, make sure it is heading hold and that you can decrease the control gain to almost nothing. when you have too much, it will over correct. while the yaw will not actually respond to the rudder imputs frantically overcorrecting becuase it is a kind of gradual thing, the model will become unstable along the axis on which the thrust has been brought down to change the torque. if you go tilt rotor you may have the same problem except it will probably respond more and quicker, but then again you might not have that problem at all. i personally do not use a rudder gyro because the only one i have (i can not afford another) has a minimum of too much control gain. while it will still fly, it isn't as fun and when the model sudeenly turns from a gust of romething it it really tough to recover. i am sorry, i messed up in my earlier post about how i fasten the props. on first (the bottom) goes a single 3mm nut, you can use either normal ones or locknuts it really won't make a difference. then i slip the prop over a nylock and bring it down the shaft. i then put two normal nuts on the shaft (they use less space) and tighten them against eachother at the very top of the shaft. once i have don e that, i will tighten the prop against the top nut so the bottom one doesn't break loose. then i take the first nut i put on, the one that can be either nylock or regular, and fasten it holding it and the top one and tightening them against eachother and the prop is very secure. it still doesn't hurt to check it every now and then (best before every flight) becasue sometimes if you hit the prop the nut will break loose and endanger your model. just becasue you can fly a heli doesn't mean you can fly this model. i have flown conventional helis (rc) although i do not own one myself. they fly very very differently, but it may be easier.