Hey,
I have been watch some of the turn back and land videos on the RV4. Very interesting indeed.
Is it known what the approximate glide ratio is for that aircraft during those evolutions?
I'm just trying to relate your results to similar antics I do in other aircraft.
Glide ratio is not a great measure for comparisons but I don't know how to ask about
any kind of verifiable measure of energy state. My prosaic "understanding" is that an
AOA system can give you tools to stay efficient relative to bleeding energy during various
maneuvers but I get the feeling that when one says "energy looks good" that is based on
it looking like you're going to make the field. (Nothing wrong with that if your aircraft is
predictable on those fronts.)
I used to operate an airplane that gave exactly NO warning of near stall if you weren't
kind of loaded up (g load) and as a matter of self preservation I always did approaches way on the fast side using lots of runway. AOA would have been really keen in that context.
I do most of my flying now in a gyroplane and on those you can bank and yank very
near touchdown and there is no risk of departure at all. Sink rate increases with bank angle and the rotor speeds up but that just makes it easier to flare as long as you remember to
make it straight and fast enough before touchdown. Still a matter of energy management
and death awaits inattention, but I wonder if one could plug in rotor disk AOA (defining
and measuring that is complex I fear) and rpm to
the onspeed gizmo and get some indication of what the usable energy state of the system
is. For sure you don't want to be looking anywhere but outside during this kind of operation
so the aural thing is a real boon.
Regards, and thanks for keeping the testing video coming. Very informative.
b
It's about 12:1 (light weight, fixed pitch prop). Actually, for turnback performance, the climb angle to glide angle ratio is what's important--if it's greater than 1, you can generally turnback after reaching minimum turnback altitude. Since the -4 has such low power loading and good climb performance, it's got a fairly low minimum turnback altitude. The great maneuverability helps.
You are correct: when I say "energy looks good" it's just an indication I've got a warm fuzzy that I'll make the field. With power available, an "on speed" condition is also neutral excess specific power, so thrust and drag are balanced for a given weight (gross weight x G). An on speed glide is actually maximum endurance glide. So in those sense as well, "energy" is good. In other words, your prosaic understanding as well as your observation are correct.
The RV-4 has almost no natural stall warning at low G, and limited buffet even at high G. The progressive stall warning the system provides is outstanding. The nice thing about an RV, is if the stall doesn't result in a departure (spin), recovery is prompt. In a loaded turn, there is a distinct loss of lateral stability.
I can't offer any gyro plane advice or opinon--well outside my field of expertise; but sure seems interesting!
The "eyes out" functionality of the aural cues is really outstanding. Once you get used to flying with this much alpha/energy feedback, you feel naked in an airplane without it. We've noticed that as folks transition to alpha for approach and landing, one of the first things they realize is that they were carrying too much energy (airspeed) when they were only referencing the airspeed indicator.
I sure appreciate the note,
Vac