Stall spin margin

[JonJay]

Some great advice here. Good on you for the self critique. The overshoot has been discussed here as being one of the most deadly concerns with our RV's. Many round off the base to final leg and you can end up close to the runway without an established approach. Looks cool, but if you establish an approach, you can't overshoot, or you overshoot well in advance and can make simple coordinated adjustments to establish a stable approach.

I doubt you where close to a stall, however....

By the way, after a couple RV accidents attributed to this exact scenario, I went out and practiced with the purpose of making bad things happen. I set field elevation simulated at 3000', lined up a road for my runway, and did all kinds of slips, skids, overshoots, cross comtrolled, uncoordinated final turns, you name it. I was surprised how difficult it was to stall/spin. My particular airplane will made a huge shudder and a lot of noise before she breaks, but that wasn't at gross.

[Vac]

Blain,

Good questions...the short answer is I don't know of a situation where a handling technique such as you describe is appropriate in the traffic pattern (or close to the ground). There isn't any reason for uncoordinated flight unless you're are intentially slipping to dissipate energy or cross-controlling the airplane during the round out and flare to compensate for cross-wind. The over- and under-shoot shoot examples in the video link I posted are all flown in a coordinated manner. If conditions warrant, it's safer to simply execute a wing's level go-around and fix heading using coordinated turns after the airplane is safely climbing away from the ground.

As for "three bars" being sufficient energy margin, that depends on how your AOA system is calibrated and performs, which requires flight test. It might be plenty of margin, or it may not. The only way to know is to validate AoA performance against known parameters (generally airspeed derived from conventional flight test) as well as evaluating handling characteristics at different AoA indications (including slip testing as you mention). Every RV is a bit different. FWIW, my RV-4 is almost 20 years old (I've owned it since 2009), I've flown several hundred hours of test and maneuvers validation in it, and I'm STILL testing it and learning--such is the nature of experimental aviation.

The other thing to note is that there hasn't been a flight control or warning system built that a pilot can't beat (just ask the folks that work the flight control logic in fighters!). In the case of an RV, two things can happen: first, it's possible to move the mechanical flight controls so fast that the airplane doesn't have time to respond to the input, and second, you can generate sufficient turn rate/G to "beat" any CAWS (caution and warning system). For example, my AoA system is only capable of keeping up with G onset rates of 2 or less G's per second. So if I stall at high G using and abrupt control input (> 2 G/second) I'd likely stall before I heard a stall warning: https://youtu.be/3avXLYp68HY. Note that in this example, you heard the slow tone, but not stall warning before the nose stopped tracking (which is what an accelerated stall looks like in an RV). In the next example, I "beat the system" for the first stall, but it caught up for the secondary stall: https://youtu.be/DLtamTAh-Is. This is one reason why there is a consistent strain of SMOOTH flight control input throughout all of Van's writing on the subject.

Fly safe,

Vac

[Toobuilder]

Originally Posted by Blain

Too complacent with the "feet on the floor" (not really on floor) because of the minimal adverse yaw...

Good on you for identifying the problem.

I took an experienced, but rusty 172 pilot for a fam flight in the -8 last weekend and demo'd stalls and simulated base-to-final stalls. In the extended stall sequence (stall held for 2000+ feet), I gave ample demonstration on how the rudder was the primary wing leveler control and also how aileron use exacerbated wing drop. Despite his nodding in apparent understanding, he could not get his feet to do anything, and could not break the habit of attempting to pick up a wing with the stick.

Everyone latches on to certain things differently as well as trains differently, so I can't offer you any specific advice other than to figure out how to train yourself to ALWAYS work the rudder correctly when low and slow. Improper rudder use is the real killer in these "base/final, stall/spin" scenarios, so do what you have to get those feet trained.

[Blain]

Michael got me thinking about my training.

I came from a Robinson R22. Working the feet is pure yaw and not a means to level the rotor. So there is something to overcome. With the doors off (my favorite way to fly the -22) the VOX mic became an aural yaw warning. If not tracking straight the wind would break squelch. (if you miss the yarn as described below)

One advantage that it did give me is smooth, light and not abrupt use of controls.

Frank Robinson is a master at reducing weight. Instead of inclinometer or gyro he used a simple piece of yarn at the center of the bubble. Sort of a crude "Heads up" display. I think I'll procure a piece of yard from the wife's craft supplies

[ty1295]

Back in April I spent 5 hours of training with Patty Wagstaff and her instructor Allan down in Florida. 4 hours was in the Super D, the 5th in the extra 300. One of the last things Allan showed me was this very "Trap". Leading up to it, we obviously spent some time doing stalls, spins, loops, rolls, etc. He got on the radio and told me he was going to show me what is killing the most pilots and he would do all the flying and to just watch.

Sure enough at altitude he setup for base to final, got slow, then put in some wrong rudder and the plane stalled and flipped on its back quicker than I could say Vans. At this point he got on the radio and declared "YOUR AIRPLANE". As a low time pilot with lots of time looking up while building it was eye opening and something I will always remember. Not to discount my initial training prior to my license, but for sure life changing and I suspect will be very valuable now in keeping me safer.

I suggest everyone SAFELY do this with instructor, etc. and get yourself in a bad situation at altitude and learn to get out quickly and safely.

[Blain]

Originally Posted by RV8JD

Won't do much good on our RV's with the tractor engine arrangement and the prop's rotating slipstream.

("Step on the ball, step away from the string!")

I guess I didn't think that one through......

[Malndi]

Originally Posted by ty1295

Back in April I spent 5 hours of training with Patty Wagstaff and her instructor Allan down in Florida. 4 hours was in the Super D, the 5th in the extra 300. One of the last things Allan showed me was this very "Trap". Leading up to it, we obviously spent some time doing stalls, spins, loops, rolls, etc. He got on the radio and told me he was going to show me what is killing the most pilots and he would do all the flying and to just watch.

Sure enough at altitude he setup for base to final, got slow, then put in some wrong rudder and the plane stalled and flipped on its back quicker than I could say Vans. At this point he got on the radio and declared "YOUR AIRPLANE". As a low time pilot with lots of time looking up while building it was eye opening and something I will always remember. Not to discount my initial training prior to my license, but for sure life changing and I suspect will be very valuable now in keeping me safer.

I suggest everyone SAFELY do this with instructor, etc. and get yourself in a bad situation at altitude and learn to get out quickly and safely.

I think the instructor demonstration in this video makes your point, it was discussed here about a year ago: https://m.youtube.com/watch?v=8wPCaazpU5k