Commercial maneuvers in the ES

[Dan OBrien]

My tentative plan is to try to get my commercial and additional ratings in my ES. This is not happening imminently -- I'm just starting to train for it. But I thought it might be helpful to have a thread on the speeds to use for the commercial maneuvers.

Maneuvers in the commercial rating that are not performed for the the private rating include:
1. Steep turns (at 50+ degrees rather than 45)
2. Steep spiral
3. Chandelles
4. Lazy Eights
5. Eights on Pylons

I'll start with steep spirals. The standard for the check ride says use a maximum of 60 degrees of bank, and the lessons I've read suggest using best glide speed. Suppose we aim for a 50-55 degree bank, and assume that wobbly flying might give a bank as high as 60 degrees. We want a stall margin in case the bank angle inadvertently increases. The stall speed with a load factor of n is Vs,n = Vs x n^(1/2) where Vs is the stall speed in straight and level flight and n is the load factor. The load factor is (1 / cos (bank angle)). (I'm getting this stuff from Aerodynamics for Naval Aviators, which is excellent for math heads.). My stall speed in straight and level flight at the weight I'll likely be at for the check ride is just below 70 kts. Let's call it 70 to be conservative. At 60 degrees of bank, which is the max used for a safety margin, the load factor is 2 [= 1/cos(60)], which means stall speed in a 60 degree bank exceeds the straight and level stall by a factor of 1.414 [= 2^(1/2)]. This gives a stall speed in a coordinated 60 degree bank of 99 kts.

Hmm... The speed I typically use for best glide is 100 kts, but that speed would not give me the stall margin I'm looking for. My thought is to increase speed on the steep spiral to 110 kts to provide the margin I'm looking for. For banks of 50, and 55 (which is where I want to be), and 60 degrees, which is the max if I control the error, the stall speeds work out to be

50 degrees --- 87 kts [= 70 x (1/cos(50))^(1/2)]
55 degrees --- 92 kts [= 70 x (1/cos(55))^(1/2)]
60 degrees --- 99 kts [= 70 x (1/cos(60))^(1/2)].

I would have a decent margin at each bank angle. Happy to hear your thoughts about using 110 for this maneuver.

[Ryan Riley]

Dan, I love that you're doing the math and research on the maneuvers so far ahead of time. As you're finding out, the ES efficient airfoil has an increased stall speed compared to a "trainer" aircraft. Here's my recommendation for your speeds. For the steep turns, I recommend you pick something under Va, which is between 117-143 kts (2000-3000 lbs). You'll have to do your weight and balance, but I think in a typical 2 ppl + fuel, if you fly the steep turns at 120 kts, you'll be at, or under Va.

I recommend this airspeed for several reasons; first, below Va keeps you from over-G'ing the aircraft (always a good thing), and it also coincides with top of the white arc. ES drives spend a fair amount of time around the white arc, both for VFR patterns as well as for instrument approaches (prior to the FAF). Also, the ES AoA at 120 kts is fairly low, but as you slow below that speed without flaps, the nose up required for level flight increases pretty quickly. And finally, 120 kts gives you 10 more kts of stall protection should you bleed off 10 kts in the steep turn, which is within the FAA checkride criteria. If you start the turn at 110 kts, slow within checkride criteria, you could be at 100 kts, which is basically stall speed at 60 degree bank.

For your best glide airspeed, each ES is built a little different, but best glide is usually halfway between Vx (85) and Vy (105). So, your best glide is probably around 95 kts. Don't take my word for it, since your airplane is unique as an experimental. The next time you're working on your Commercial maneuvers, try doing some engine out speed analysis. Here's my recommendation on how to do that. First, start at least 3,000' AGL, next smoothly pull the MP to idle, mixture in, and then pull the prop lever out, thereby decreasing your rpm and simulating an engine out and feathered configuration. Once trimmed and feathered at 100 kts, take note of your VVI. slow to 95, then 90 kts, then back up to 120 kts and take note of your VVI at each of these speeds. Report back and you'll be surprised at how these speeds will affect your glide performance.

Lastly, on engine out procedures, I teach my students engine out math as well as practice to fly to a High Key position (2,500' AGL), and do a continuous 360 degree spiral while configuring along the way as you assess your energy. In the military this is called an Emergency Landing Pattern (ELP). This maneuver does two things; 1) if you have the energy to get to either high or low key, it greatly increases your odds of successfully making the runway vs a straight-in glide, and 2) it is a repeatable pattern that allows pilots to assess their energy state and make corrections.

Disclaimer: if you have not done some of the maneuvers that I've described in this post, please find a LOBO instructor and we'll be happy to work on any/all of your commercial maneuvers as well as a host of emergency scenarios. If not, at least have a safety pilot. I hope this helps and fly safe!

[Dan OBrien]

An update: I've done two flights with an instructor helping me prep for the commercial. He's not a Lancair instructor, but I chose him because he's in a flight school with a DAR who is willing to do a commercial checkride in an Experimental. I found the DAR on the RV List. I figured it would be useful to fly around the airport from which the DAR does the tests and learn from someone who gives him lots of students.

My flights have been GREAT. The first flight had the instructor get to know the airplane. We did every stall imaginable, and went deeper into them than I did while flight testing, where a degree of nervousness about it made be be very cautious. Findings: THIS PLANE IS AMAZING. The instructor is stunned at (1) the speed of the plane and efficiency of the wing; (2) the amount of warning in stall (my AOA, very nose high angle, and significant buffet from the inside to out); (3) the relatively docile nature of the stall; and (4) how quickly the airplane is flying well after lowering the nose from the ridiculously high angle required to induce a power on stall. We've done every maneuver to determine optimal speeds, climb angle for the Chandelle, altitude for the steep spiral, etc. etc. So far, the testing has shown that in fact this is an EXCELLENT plane for commercial maneuvers. Of course, I'll have to produce it, but any failure will be me, not the plane. I'll say this -- the testing (just two longish flights to this point) has massively increased my confidence in this airplane! I tend to be a nervous flyer to the point of being extremely cautious. But the testing we've done has shown me better what this plane does at some of the corners of the envelope, and I am more happy than ever with this wonderful airplane. He said its actually better behaved in some ways than his 152 -- imagine that. Why did Lancair have trouble certifying it and have to make all the changes they made to get the Columbia? It seems like this baby has one of the most efficient wings on the planet. He notice that it has lots of washout, and stalls nicely from the inside out with lots of buffet. What problems did Lancair encounter?

[J.C. Peterson]

Why did Lancair have trouble certifying it and have to make all the changes they made to get the Columbia? It seems like this baby has one of the most efficient wings on the planet. He notice that it has lots of washout, and stalls nicely from the inside out with lots of buffet. What problems did Lancair encounter?

It largely came down to spin resistance/recovery. There was a video around years ago of an owner doing his own spin testing that pretty quickly developed into something that looked unrecoverable. If I recall correctly he said he thought he was dead, but managed to recover with very little altitude left. The airfoil design was for speed not high AOA handling and recovery. Stall strips help with this, but departures from controlled flight still tend to be quite abrupt. Standard recovery techniques may or may not work.

There was also this accident:
https://www.oregonlive.com/breakingnews ... kills.html

[Dan OBrien]

It largely came down to spin resistance/recovery. There was a video around years ago of an owner doing his own spin testing that pretty quickly developed into something that looked unrecoverable. If I recall correctly he said he thought he was dead, but managed to recover with very little altitude left. The airfoil design was for speed not high AOA handling and recovery. Stall strips help with this, but departures from controlled flight still tend to be quite abrupt. Standard recovery techniques may or may not work.

There was also this accident:
https://www.oregonlive.com/breakingnews ... kills.html

Thanks J.C. The article doesn't provide information on cause--maybe the report has it.

The instructor I've been flying with in a flight school run by the DAR I found willing to do a checkride in an experimental is experienced with spins. We went through various stalls and found recovery fast and easy, but he did say that he didn't think he would spin the plane. He noted, as I believe others have, that the vertical stabilizer & rudder may be a bit smallish relative to the size of the wings and horizontal stabilizer. He worries that rudder authority might not be enough to recover from a spin, particularly with a more aft CG. Is that consistent with your understanding of the ES handling qualities?

In any event, I am much more comfortable with stall characteristics and recovery in the airplane than I was before launching into the commercial maneuvers. On power on stalls, the nose is at a very high attitude before it stalls. There is plenty of buffet. The warning simply can't be missed. You'd have to be screwing around to get there. On power-off stalls, the warning is somewhat less, but if the rudder is coordinated, the stall is very gentle, at least in my plane. I think one would have to be quite uncoordinated to get in trouble and spin. This is admittedly with two people in the plane and a reasonably forward center of gravity. We approached an accelerated stall in about a 50 degree bank until first feeling the buffet, which was quite noticeable. Not sure how you'd get there either, unless you were hot dogging or trying to to make a steep bank on an approach.

[Admin]

Dan, for about 4 years I spun weekly in the T-6A the Air Force uses for its primary trainer. Spins have three phases. 1) Entry, 2) Incipient, 3) Fully developed. Most upset recovery training done in a spin-certified aircraft is done at either the Entry or Incipient phase because recovery occurs quickly. I've spun an MX-2, several gliders, and the T-6A. Each of them wrapped up pretty well when allowed to transition to a fully developed spin. Some of them even take 2-4 turns to pop out after spin recovery is initiated.

Bottom line, the ES was not spin tested and I am not a test pilot, therefore spinning is off the table for me. Could the ES structurally handle a spin - yes. Does it have enough rudder or elevator to break a spin in an aft CG configuration...I don't know.

Since you're on the path of discovery during your commercial training, see if you can find someone to do upset recovery. It's great training and a great confidence builder. I recommend a super Decathlon as they are a ton of fun to fly and you get some tail dragger time as well.

Give me a call if you want to talk more spin stuff.

-Ryan

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[George Wehrung]

Dan,

Your instructor is correct about staying away from spins. We don’t spin any of the Lancair models. Also the ES is the only model of Lancair that is stalled.


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[J.C. Peterson]

We don’t spin any of the Lancair models. Also the ES is the only model of Lancair that is stalled.

Don’t forget about the Evo. One setup properly with stall strips according to the build manual and verified by flight testing can absolutely be safely stalled. The ones without stall strips are often another story, especially at heavier weights and/or aft CG ranges.

[George Wehrung]

Oh yes, you are absolutely correct Sir. I forget about the EVOs all the time.


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[Dan OBrien]

Here's a puzzler. The IV has the same wing as the ES only smaller, or so it is said. Something like RXM5-217 airfoil at the wing root, transitioning to a NACA 64-212 at the wing root. My ES has a gentle stall (at least at the beginning), and when the nose is lowered just a bit, it is immediately flying.

But we hear different things about the IV, which has the same airfoil, albeit, but much higher wing loading because the wing is smaller. An old article in one of the magazines talks about a right wing drop, possibly a big one. Given the same airfoil, what explains the difference? Does the smaller wing and thus higher wing loading on the IV explain it? Does the ES have more washout? Something else?

Just a puzzler.