Quote Originally Posted by Wylbur View Post
I've done some searches and VMC is not found in EAA forums. I would assume that's because no one seems to want to tackle a twin (except for the Twin JAG).

For those of you who have aircraft engineering experience, or multi-engine piston a/c time, I have a question. How does one project what the Vmc would be?

And why is Vmc where it is for a particular a/c? Example: For a Seminole, Vmc is less than Vso. For another plane, Vmc is > 80KIAS and Vr is ~65KIAS (so pilots accelerate to Vsse and then rotate).

If you used pusher props with wing mounted engines, would you even have Vmc or would it be well below Vr?

Do jets have Vmc? I've never heard of such for a jet, just V1, where if you lose an engine by that point, you chop power and stop.

If your engines are mounted on the sides of the fuselage, does that prevent there being Vmc, and does the FAA consider this an inline thrust situation? I would bet that you would still need rudder to control yaw in that case.

Just someone with an inquiring mind trying to figure out a multi- design.

One last question: Does an E-AB have specific G loads to meet for the wings? Could one design around "transport" category (+2/-1 G I think is the requirement)? After all, if you design and build a plane for 6-8 people, would you really want to do 90 degree banks on purpose?

Regards,
Wylbur
Wylbur - based on your posts in this thread, it occurred to me that a "design study" might be helpful to you. That is, compare existing aircraft that are comparable to your requirements and you'll find a range of solutions; wing area, aspect ration, power, power loading, empty and max weights, tail volume (square footage of the vertical stabilizer and rudder multiplied by the distance from the aft edge of the C.G. range). Again, based on your posts, it seems that your thoughts are akin to the Navajo series and Cessna 402s.

Once you've digested that information, when you design your own twin, if you come up with answers that are significantly different than the design study aircraft, you'd best rethink those answers. That is, there's a reason existing aircraft are set up the way they are (and in the end, you might discover that it's cheaper to buy a twin than to build one - some twins are relatively cheap right now (who wants to pay the fuel and insurance?)).