- Oct 30, 2003
- West Valley City, Utah, USA
- Sport Copter Vortex 582
- Total Flight Time
- FW: 200 Gyro: 51
Vance, I think the theory is that in an engine-out vertical descent, the airflow to the rudder is blocked by a horizontal stab mounted fully below it. But a cruciform tall tail can't be much better, since the H-stab is still at least halfway blocked.It has been suggested that having the horizontal stabilizer on the bottom limits rudder authority in an engine out vertical descent...I have trouble imagining the horizontal stabilizer having much effect on yaw or the rudder authority...
For that matter, what if you had no horizontal stabilizer at all? In a vertical descent with the engine out, the rudder is seeing only edgewise flow, so moving it does nothing.
I would think the answer to any of these situations is to put the nose down a little and spiral to get airflow (in the proper direction) over the rudder. True vertical descents are fun, but I'm not sure they're ever really needed.
Given your experience and confidence in the Predator, just go out and shoot some very high approaches and use vertical descents to get down, and see what happens. With the engine at idle, the machine will want to slowly spin, due to the "dissymetry of thrust" as the spinning prop slides edgewise through the air, but in a true engine out, (if you're comfortable to try,) you should be able to come pretty much straight down.
And if it works in the Predator, it should work in Mariah Gale.
In an engine-out descent with forward airspeed, an aerodynamically cleaner fuselage should help rudder authority, too.
As for tail volume adequacy, can you approximate "fuselage volume" (or whatever the technically correct term is) ahead of CG, and compare?