Indeed, the market has voted. SEP. That is hugely to the advantage of anyone who wishes to fly a twin as you get a very disproportionate amount of aeroplane for your money. I’m pretty happy with that.
Ibra wrote:
Let me check my understanding: you can “safely operate a twin bellow VMC on one engine” by shutting down or reducing power on the good engine?
If one engine quits, and you cannot maintain directional control, yes reducing power on the other engine will reduce asymmetry. But, for most light twins, you will no longer have enough power to maintain level flight, and you will have to enter a rather steep near glide to build up the speed you should have had already to be at Vmca. That’s going to cost you a lot of altitude. If you have that much altitude to spare, you probably already had the time to handle the engine failure as an in flight emergency, rather than an EFATO.
I’ve flown in flight single engine testing on types from a Twin Comanche and DA-42, to Navajos, King Airs, Twin Otters, and turbine DC-3. With one exception, non of the twins I have tested on one engine left me confident of much performance, or room to play around below Vmca.
There are a few twins which have lots of power, or are aerodynamically unusually good, where these tricks have a better chance of working. Referred above, I once shut down an engine in a Piper Cheyenne II. The plane was light, just we two pilots. That plane had lots of extra power, and once trimmed, you hardly knew that you were flying only on one engine. A Vyse climb would not have been a problem, though we still did not attempt it!
When I did my multi rating test back in the 80’s, I had a Cessna 310R to use. I had to seek out an examiner familiar with the type, as they are not a common training plane. I was happy that I did find a really type experienced examiner. He had me set up stable Vmca flight. I set it up exactly as the POH said – and the plane was gently turning toward the dead engine. I worried that I had got it wrong, but he laughingly reassured me that I had done it right, he knew that the POH speeds were a little optimistic. I flew it a few knots faster, and it was fine.
Cessna 337 Skymasters are a different thing. If the rear engine quits, aside from a huge loss in performance, it’s hard to tell – no yaw! It is type discipline that for takeoff you lead with the rear engine, and get the plane accelerating on that engine, check power, then open the front engine throttle (this is better for the props too on a loose surface). That said, flown properly Skymasters are a nice twin.
The answer to all these issues is not to operate near Vmca. If that means longer runways, so be it. Twins generally need longer runways than singles, a fact of life that limits their utility somewhat.
Personally, I won’t use a runway shorter than balanced field length (ie you can get up to rotate speed (typically 12-15kts above Vmca), think for two seconds, cut both engines and stop before the end) except in exceptional circumstances.
Timothy wrote:
a fact of life that limits their utility somewhat.
I dont entirely follow – the bfl of many twins doesnt seem to me to significantly limiting. Of course there are farm strips that you would be happy to visit in some singles that would not work, but the performance comparison with many high performance singles is not that significant and some twins will handle grass far better than some high performance singles – Cirrus and TB20 come to mind.
Yep. I guess I was comparing Navajo to C172. If you compare it to PA46, the numbers are similar.
TB20s take for ever to get off the ground. 
You wouldnt want to make that comparison.
You should try a TB9. Actually, scrub my earlier comment about the flat earth society. Curvature is all that gets a Tobago airborne.
You should try an SR20, it eventually commits reluctantly to aviating. Its even more fun in the heat of Florida, but fortunately they dont believe in short runways. I think the bfd of all three is considerably more than a lot of twins.
Strange I dont think many SEP pilots think of BFD, and in one way a twin becomes a single if you close both.
Timothy wrote:
Curvature is all that gets a Tobago airborne.
Quite some French planes do that. A340-100 to 300 anyone?
Timothy wrote:
Personally, I won’t use a runway shorter than balanced field length (ie you can get up to rotate speed (typically 12-15kts above Vmca), think for two seconds, cut both engines and stop before the end) except in exceptional circumstances.
Looks like a good concept where possible.
Even in SEP’s often enough people use runways which will be within the ground roll distance but not the total distance. Makes for exciting take offs. Often enough however not much choice with the airfields available. Obviously balanced field lenght is a concept which not many SEP pilots even know about… and which some MEP’s should remember. I’ve done some unbalanced take offs in my time with the Senecas from 500 to 700 m runways… feasible but not my favorite way to depart. Then again, looking at some unbalanced take offs I’ve seen in my time e.g. by the old Pan Am 747-100 series out of ZRH…. lots of excitement and at least in two cases of EFATO followed by a VERY low pass over the nearby village while dumping fuel…
