ROB-x38 and all.
Welcome aboard. I think we need a few more than a quorum before we are through with this.
Ok lets go fly your twin.
We have climbed to a safe height, closed down the left engine, upped the power on the right engine and settled into a steady straight cruise with wings level and found that the rudder is trimmed right foot with about one third deflection. Balance ball is in the centre even though we know we are sideslipping by about 3 degrees. Hard to tell though.
The R foot rudder plus a considerable contribution from the fin and rear right fuselage is balancing out the thrust from the R engine which would otherwise be yawing us strongly to the left.
We don't like that amount of rudder applied. It has reduced our options for lower speed flight down around Vmca and as flight testing has shown (and we may instinctively suspect) we are able to carve off some drag by banking a little into the live engine. A bit more aileron than the few degrees we already have applied you say. Well OK we suffer a little extra drag there but hope to lose more than that by a reducing rudder deflection.
So roll over by about 1 degree and retrim all round. What has happened is that we are now back to about 1/4 R foot rudder deflection. The small lift component is now trying to pull us sideways a bit causing additional side force on the fuselage, which has its greatest surface area to the rear, taking over some of the previous task of the rudder. That feels a bit better.
Roll on another 2 degrees. More lift component and greater tendency to slide to the right causing more side force on the rear fuselage.. Compensate for this by taking off some more rudder. Retrim all round for straight level flight.. Now we only have about 1/8 R rudder. But what about that crazy balance ball. Its now hanging off the centre of the instrument by the angle of bank. Still nothing except instinct to indicate we are sideslipping.
Now roll on another 2 degrees. More lift component, more sideways force, more sideslip, more compensating force from the rear fuselage. Retrim all round.
Hey - rudder is just a nat's whisker away from centre. That feels great but that crazy ball is now out further. Want to cover it? It's not much use to you now unless you reset in your mind its current position as being the new datum to use in turns.
Somewhere as we increased the angle of bank we went through the minimum drag point. Maybe we are right on it now in that we have a central rudder, the rear fuselage having taken over from the rudder. I would suspect that a little touch more bank to cause the rudder to be a little to the left would be the minimum but why worry as the shape of the drag curve in this area will be fairly flat.
What happens when we try more bank.?
OK roll on another 10 degrees R to a full 20 degrees. Now it’s a bit of a lead sled. We've had to trim nose up to compensate for the much larger portion of lift we are using out to the side and to keep us going straight you now have almost half right rudder out the other way. Drag has shot up considerably and we have now stabilised just above Vmca for the power we have.. The side slip is gross.
Roll on another 10 degrees. Hey is that full left rudder?? and come on keep your nose up. Don't let it yaw right like that. Hey you're losing it. Look at your speed.
TAKING OVER.
Nose down and wings level, power off , I'll get the power coming on gradually as our speed increases. Lets get that other engine going or will we check out your personal minimum control speed. You may even be able to get it back to the stall.
By the way do you know whether you can stall the fin on this type. Fin stall often has nasty consequences.
A bit simplistic to the experienced but we aren't all so endowed.
Last edited by Milt; 13th September 2004 at 08:49.