2017 Going out with a bang.....Flat Turns

[Aesquire]

In the next to last paragraph, he writes that, when approaching a stall, “...the only thing that you will see out front is the sky while the wingtips quickly approach a perpenduclar relationship with the horizon”. That is not credible.BJC

You can say that about several airplanes. Just Aircraft's SuperStol, Cub clones with leading edge slats or slots, etc. Perpendicular is a bit more than factual but it can seem like that if your standard is a RV-9 or Bonanza. The view out the wind screen especially from the back seat is just sky in a lot of planes at slow speeds. I don't mind the looks of a Storch, it has purpose and looks like it. Why can it do flat turns that look dangerous? Pilot skill, low wing loading and stall speed. And I think a bit of illusion. It is a potentially dangerous maneuver, but the slow speed hides the margin from an observer. If it hides the margin from the pilot? He stalls. A lot of "forgiveness" in airplanes is how much you can feel the stall before it happens IMHO. There's pilot variation in "butt sensitivity" too. You may be able to feel the wind letting go of your wings and keep it flying where I would slide over the line without noticing until suddenly I'm looking down and wondering why the brown is spinning.

 

[Highplains]

The Army Guardrail program used King Air's covered with antennas for their sigint work. Those airplanes have to fly flat skidding turns when collecting signals.

 

[Dan Thomas]

Perhaps the Australian accident investigators assumed that the pilot wasn't deliberately doing a flat turn? Who on earth does those on purpose at low altitude?

Because of the wind, they blamed the illusion of drift for the crossed controls that result in a skid, which is the proper and accepted term for a "flat turn." If you are flying along into a headwind and then turn either way, the airplane begins to drift over the ground toward the inside of the turn. It gives the illusion of a slip and the unthinking or uneducated pilot tends to reduce bank (which is one component of a slip) and maybe add rudder to keep the turn going as the bank decreases. This is the cross-controlled condition that has killed so many people at low level in overshot base-to-final turns or in fooling around at low level, especially if the winds are stronger. You have to keep the ball in the middle even if the airplane seems to be sliding sideways. Some people who haven't done this think the ball will be off to one side in such a state, but it won't be. The ball reacts to gravity, which operates in the vertical only, and to the centrifugal force of the turn, which is happening regardless of the illusion. One of the things we'd do to convince students was to make them do these turns under the hood, relying only on instruments, and they could not tell us which way the wind was drifting them. If you can't feel it, the ball sure can't.

One of the unfortunate aspects of ailerons is that they increase the wing's angle of incidence over the aileron's span, which increases the AoA, which brings on the stall sooner. That, as you say, is an unchangeable law of physics. Many designers have tried to minimize the threat using washout, differential aileron travel, spoilers, airfoil changes in the outer span, and so on, but the threat is always still there. Slats lower the overall stall speed by increasing the stall angle a little, but that just leads pilots to fly even slower and end up just as close to the stall as they would have without the slats. Slats are for improving short-field performance, not for preventing stalls and spins. Same goes for VGs, drooped leading edges, and some others. Some of these mods result in the airplane being placarded against intentional spins altogether because the spin recovery has been badly compromised.

 

[Winginit]

Slepcev Storch is nothing more than an airplane. Someone filmed a flat turn; cool. Any airplane can do the same thing as long as the pilot know what he is doing. Latched upon by an internet spec hunter. I did it in high school reading Road and Track, Car and Driver, and Motor Trend. For some reason Motor Trend had the hot shoe then; they were always the fastest when they wrote the articles. Then you learn each magazine had different testing criteria, so it really was not apples to apples even with the same cars. MT used a prepped track, C&D seemed random, and R&T did it on street like conditions. Unless you can fly it; it is subjective banter.

Which means a regular ole' plane can do the same thing as it's subject to the same physics. A Cessna 150 can make a flat turn at slow speed with the stall horn blaring. Is it efficient? No. Is it safe? Relative to what? A coordinated turn? Can one tweak the 150 to make it perform a flat turn better? Sure, but at what cost? One can design a safe plane but at the end of the day there has to be more checkmarks in the "pros" column than the "cons" column of it's going to be a flop.

In the particular pair of journalistic revues I provided, both authors came to the SAME conclusions, not different conclusions. The test flights were performed ten years apart by totally different people.That should say something about their validity. When the airplane completed the manuevers, they became "facts". Disbelieving your eyes (previous video evidence) or disbelieving the honest and consistant reviews of noted industry professionals does not make it "untrue" . I'll quote what one of them wrote. " but the serious point Ben was making is that the aircraft is so incredibly stall-and-spin resistant,(edit) that it offers unique safety margins when flown low and slow." As for the "pros and cons" and being a flop, they have been in business now for over 20 years, have expanded to offer larger models, and seem to be thriving. Again, the point of this whole discussion is not just being able to perform flat turns, but the increased safety margins that are being demonstrated by either "not spinning" or "being less likely to spin", depending how someone wishes to interpret the information. Yes, there may be other airplanes that can perform a flat turn to some extent, and Yes there are modifications that can be made to augment their abilities. In this case the designer applied the laws of physics in a manner more consistant with slower flight and controllabilty during slow flight than the designer of the 150 did. Different goals, different results. That being said, I feel that someone approaching a landing in a Storch will have a much wider margin for error than they would in a 150. Remember, one of the major causes of fatalities in aviation is the stall/spin at low altitude when landing. Anything that improves that margin for error is a definite improvement, but it usually comes at the expense of other qualities....like speed. Making a flat turn at low altitudes and landing speeds in a Cessna 150 is hazardous no matter what you wish to compare it to. This airplane will not compete with a 150 in cruise, but it will dominate a 150 in slow flight control...thats what its purpose is and why its design is such that it utilizes the laws of physics efficiently to support its design features. Its beyond me why anyone wants to refute the idea that an airplane can't be designed that uses the laws of physics specifically to augment slow flight control and that the resulting airplane would perform no better than any airplane that had not been optimized for slow flight control.
So for hopefully the last time, this is a discussion about safety margins that just happen to be demonstrated and documented with the use of a flat turn to demonstrate those wider margins.

Those were the last two comments posted in 2017, so I responded to them with the doggedly determined hope to bring objectivity to the fore. Its now 2018 and I have done everything I know to present objective information on this subject . Those that wish to agree with what I presented, I thank you. Those that wish to hold on to a different viewpoint, I respect your right to that viewpoint, and as I said earlier, I Wish You A Happy and Successful New Year !

 

[pictsidhe]

It has a 20kt stall speed. Not many here will argue that it isn't optimised for slow flight. As for flat turns being able to be done in a smaller radius than a banked turn. Can it do a flat turn in smaller radius than a longEZ can banked? Probably, thanks to it's very slow flying abilities. But I'd put actual money on a Storch being able to turn tighter banked, than flat. As for flat turns bing handy down low. The wings are much higher than the wheels, by the time you have a wingtip down to wheel height, you actually have quite a bit of bank, and therefore, turning ability. The Storch has huge wings for it's weight, they can turn it much better than it's fuselage. I think the problem is that most of us see the airshow flat turns as an airshow stunt. Yes, they can be done, but do you really to want to try one in an emergency without a ton of practice instead of a safer and more effective manoeuvre? The Storch seems to have big safety margins, but is really sensible to use them up, deliberately?

Winginit, why not contact a Storch owner and ask him/her whether it turns tighter flat, or banked?

 

[Dan Thomas]

There are numerous "experts" out there who write articles and regularly get things wrong. Some of that stuff misleads the ignorant into trying something that kills them. And there's the danger: stating that a certain airplane can safely do something that is known by aeronautical engineers to be dangerous. Some of those engineers spent a long time in school and are also pilots or instructors. They know, both academically and concretely, what the truth is. You don't find them endorsing skidding any airplane at low airspeed. There is no magic. Just physics. Similarly, a PPL trying stuff he sees at the airshow often ends up with tragic results.

Orion had as his tagline: What you believe or do not believe does not change the facts. Opinions and physics sometimes don't agree. Wishful thinking gets you nowhere.

 

[N8053H]

I read the article, thanks.
Any plane can be made to fly in an uncoordinated fashion. Students do it all the time. Occasionally it is handy (e.g. forward slips to lose altitude). I have trouble coming up with a good reason to deliberately skid a plane around a turn, and don't see that it is a badge of honor that a plane can do it. There's nothing magic about the Storch-- when it gets pushed to skid around a turn, it will do it. It can do it at low speed, but the maneuver still produces a situation that sets the pilot up for the rapid development of a spin once the critical AoA of either wing is exceeded. Just like any other conventional airplane.

Any time you fly a steep turn you fly uncoordinated. Also a good way to know if you are in a steep turn if you are flying uncoordinated in said turn.

 

[BJC]

Any time you fly a steep turn you fly uncoordinated.

Can you explain that, please?


BJC

 

[Turd Ferguson]

As for the "pros and cons" and being a flop, they have been in business now for over 20 years, have expanded to offer larger models, and seem to be thriving.

Happy New Year Wing! Hope it's a good one for you.


How many Slepcev Storches are flying around the world? The Van's line of airplanes seem to be thriving but I would venture a guess Van's sells more airplanes in 1 hr than Slepcev sells in 1/2 a yr. Why are the SS planes not popular like Van's airplanes? Because customers feel the abilities don't outweigh the disabilities?


I agree with Dan, the turn should be called it what it is, a skidding turn as the plane uses no unique control feature that enables it to turn any differently than any other fixed wing airplane. It's maneuvered about it's three axis with an elevator, ailerons and a rudder, same as any conventional airplane. I can't believe anyone in aviation with any credibility will advocate that skidding around the pattern is safer than flying in a coordinated manner regardless of the type airplane. That's contrary to 100+ yrs of conventional wisdom.

BTW, I like unique airplanes but the SS is not really unique. By the designers own description, it's just a scaled down Fieseler Storch.

 

[Turd Ferguson]

Any time you fly a steep turn you fly uncoordinated. Also a good way to know if you are in a steep turn if you are flying uncoordinated in said turn.

Define "uncoordinated"

 

[bmcj]

Concerning the SS, unless someone can tell me that the slats actuate independently of each other, then you’ll not convince me that there is anything magical or different about the SS... it only flies slower, so the flat turn might look slow, but still be sufficiently above stall speed to keep both wings unstalled (as long as you don’t let it slow).

Any time you fly a steep turn you fly uncoordinated. Also a good way to know if you are in a steep turn if you are flying uncoordinated in said turn.

Don’t confuse counter aileron input with uncoordinated flight. The counter aileron is entered to prevent increasing bank due to the outside wing flying faster in a steep turn. Even though you have a bit of outside aileron, the resultant gravity (load) vector can still be straight down through the aircraft floor.

 

[mcrae0104]

But I'd put actual money on a Storch being able to turn tighter banked, than flat.

An echo from the past!

This was exactly my point in one of the prior flat turn threads. Couldn't find it today, but it was illustrated with diagrams and the physics that a combination of the rudder and a skewed thrust line could not possibly produce as much turn rate as a moderately-banked turn. Note that this is true even if we concede that the flat-turning plane has enough rudder authority to skew the nose into a 90° skid from the direction of flight, and that the plane has a 1:1 thrust-to-weight ratio. Unfortunately, the poster in question chose not to criticize the straightforward math involved in centripetal acceleration and instead attacked me for not drawing an airplane that looked more like a Storch in the diagrams.

No doubt at this point, Topaz would remind us all to keep it about the post and not the poster.

In that spirit, I see no need to re-litigate this topic any further, as it has been asked-and-answered and there is no purpose in discussing it other than to shame the OP.

So happy New Year, everyone, and be charitable to Winginit by not not giving him yet another platform for this idea. I'm not going to respond no matter what he has to say about this post. Do take note, however, that he will be able to offer no scientific evidence that a flat-turning Storch can turn more rapidly than a coordinated-turning Storch.

 

[BJC]

Stork executing a low turn to final. Note the ailerons’ positions.

https://goo.gl/images/cjmMed


BJC

 

[bmcj]

Stork executing a low turn to final. Note the ailerons’ positions.

https://goo.gl/images/cjmMed


BJC

Is that a Fiesler or Slepcev?

 

[mcrae0104]

Looks full scale. I'm going with Fieseler.

 

[Winginit]

bmcj;414405]Concerning the SS, unless someone can tell me that the slats actuate independently of each other, then you’ll not convince me that there is anything magical or different about the SS... it only flies slower, so the flat turn might look slow, but still be sufficiently above stall speed to keep both wings unstalled (as long as you don’t let it slow).

.

Bingo ! Exactly right.
It flies slowly without the wings stalling.....not Magical, and not inheirently different, just optimized . Now a simple question. Could you reverse your direction more quickly if you were walking or running on a slippery surface ? The obvious answer is that the slower you are moving forward the easier it is to change direction in a tighter space.....but that is all predicated on the fact that whatever you are standing on will support you thru the whole event. The ability to create sufficient lift is key in any manuever.
. Some wish to make the discussion about whether banking will allow a tighter turn than staying level. That is irrelevant to this discussion because this is about whether or not this airplane will provide increased safety margins when flying slowly and misjudging speed or control inputs. It's not about the best way to turn the airplane, but about the ability to survive mismanagement of control inputs.Those wishing to debate the best turning radius for this airplane need to gather some real data for accurate debate and start a new thread on that topic.I have seen lots of hypothesis on the subject but nothing based on real hard data. I would be interested in seeing real data on the subject, but please do so on a thread dedicated to that subject. Thanks in advance.

There is no law of Physics that prevents the optimization of an airplanes flying characteristics so that it can still provide lift during a slow turn. It's simply a matter of knowing what the limits are. A Lancair won't turn as tightly as a Vans RV9, and the RV9 won't turn as tightly as a Storch. It's like Dirty Harry used to say, "A man's got to know his limitations".That's really all that this is about, knowing the limits of ones airplanes abilities, and deciding what is best for you.

 

[Kyle Boatright]

It's not about the best way to turn the airplane, but about the ability to survive mismanagement of control inputs.

Which is why you fly coordinated turns, not uncoordinated turns which put you closer to, not farther from, an incipient spin. Low altitude stall/spin accidents are common and deadly.

 

[Winginit]

Which is why you fly coordinated turns, not uncoordinated turns which put you closer, not farther, to an incipient spin. Low altitude stall/spin accidents are common and deadly.

Yes, of course that's why people fly co-ordinated turns....l'm certainly not disputing that. People also make mistakes and cross- control airplanes...often at the worst times.People overshoot the final turn all the time....and some die trying to make corrections. Obviously they don't intentionally put themselves into a disasterous situation...but it does happen. If everyone always flew co-ordinated turns and never made any mistakes we would not be concerned about whether one plane might get you thru a "control inputs mistake" because it's wing didn't drop. The idea is that the flat turn demonstration is just that, a demonstration of being able to maintain control of the airplane even when you inadvertantly put yourself in precarious position....not a recommendation to put yourself in a precarious position. No one is suggesting that a pilot should plan to make a landing by perfecting a flat turn on their approach, the flat turn only serves to demonstrate that a cross control mistake in a slow speed turn does not have to be a disaster every time.

 

[Vigilant1]

So, we all agree that a "flat turn" has no utility in real flying, right? It offers no advantage over a normal, coordinated banked turn.

You are citing the SS as noteworthy because, if a pilot performs this maneuver at low speed (on purpose or by mistake), the results are less likely to be disastrous than in some other airplanes? Is that what all these threads have been about? Is this really a significant measure of merit for an airplane?

 

[Turd Ferguson]

Fortunately, the standard FAA traffic pattern does not require maximum performance maneuvering to arrive on final approach in landing configuration so the plane that can make the tightest turns has no material advantage over other planes in the pattern, i.e. no safer.

The FAA says factors that contribute to loss of control "may include: poor judgment/aeronautical decision making, failure to recognize an aerodynamic stall or spin and execute corrective action, intentional regulatory non-compliance, low pilot time in aircraft make and model, lack of piloting ability, failure to maintain airspeed, failure to follow procedure, pilot inexperience and proficiency, or the use of over-the-counter drugs that impact pilot performance." all of those sound like pilot issues, not plane issues. They purposely stop short of blaming specific airplane types cause we all know pilots can crash even the safest airplanes built.