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

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Winginit

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I purchased some old magazines the other day and received them today. Since the weather is quite cold, I decided to read some of them. I found an article in one of them about the design and flight testing of .....of all things...a Slepcev Storch.As I read thru the article I came across specific information related to "Flat Turns". Now I took a lot of heat on this subject earlier in the year and the subject became quite vitrolic. Imagine my surprise when I read what I'm going to attach below and a noted aviation journalist virtually mirrored the message I tried to put forth.

To recap, I tried to state that the ability to perform a "flat turn" has mostly no apparent benefit other than demonstrating that this airplane can allow someone to make a dumb mistake and not spiral them into the ground...its very forgiving. There are instances where being able to change direction without banking a wing could prove beneficial.....such as being close to the ground and suddenly seeing an impediment in front of you. The ability to skid a partial or complete turn without banking a wing could help someone avoid that impediment. Its mostly something that helps a pilot thru a bad situation rather than something someone would want to do every time they attempt a landing.

Most airplanes simply cannot perform this manuever at landing type speeds, because their airplanes are NOT DESIGNED to cope with that situation. I get that, its a bad thing and will kill a pilot very quickly. That does not mean that an airplane cannot be designed to cope with that situation successfully. Its not breaking any laws of physics, but rather applying them in a more useful way thru application of its design features. To incorporate those features, the designer had to give up many common features or attributes that other airplanes have. It can't fly as fast as many airplanes, nor carry as heavy a load.

Now all I ask is that some of you take the time to read about this amazing airplane and what the designer did during testing. The article even makes a point of talking about how the designer configured the airplane to make flat turns easily, and survivably. I don't want to rekindle a feud again, especially with the start of a new year. I wish everyone on HBA a very Happy New year, and I hope maybe some will reconsider their opinions after reading the exerpt from the article.


Slepcev X6 001.jpg
 

Dan Thomas

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The 14th line of this accident summary has this to say about a Slepcev Storch: https://www.atsb.gov.au/media/3432943/attachment%20e%20-%20ultralight%20accidents%2000-10.pdf

The aircraft was being flown over the owner's property for the purpose of a crop inspection. An eyewitness reported that the aircraft was travelling in an
easterly direction and appeared to be travelling very slowly. It initiated a flat turn to the left and having turned about 90 degrees the nose dropped very
sharply down to a near vertical position. The aircraft impacted the ground in a steep nose down attitude. The pilot sustained fatal injuries, while the
passenger was severely injured but able to exit the wreckage. There were no other occupants. The accident was investigated by the Australian Ultralight
Federation. The investigator reported that "... this accident exhibited all the factors consistent with a stall spin situation, resulting from a down wind turn
at a low height. This occurs as a result of the pilot getting visual cues that convince the pilot that the aircraft has excessive bank, which when 'adjusted
for' results in the turn becoming flat and unbalanced, usually with the controls crossed.


The "illusion created by drift" can do that. This guy wasn't intending to skid the airplane, but he did and it killed him.

As an instructor I had occasion to teach this. https://www.tc.gc.ca/eng/civilaviation/publications/tp975-partii-ex20-5287.htm
 

Vigilant1

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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.
 
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Winginit

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The 14th line of this accident summary has this to say about a Slepcev Storch: https://www.atsb.gov.au/media/3432943/attachment%20e%20-%20ultralight%20accidents%2000-10.pdf

The aircraft was being flown over the owner's property for the purpose of a crop inspection. An eyewitness reported that the aircraft was travelling in an
easterly direction and appeared to be travelling very slowly. It initiated a flat turn to the left and having turned about 90 degrees the nose dropped very
sharply down to a near vertical position. The aircraft impacted the ground in a steep nose down attitude. The pilot sustained fatal injuries, while the
passenger was severely injured but able to exit the wreckage. There were no other occupants. The accident was investigated by the Australian Ultralight
Federation. The investigator reported that "... this accident exhibited all the factors consistent with a stall spin situation, resulting from a down wind turn
at a low height. This occurs as a result of the pilot getting visual cues that convince the pilot that the aircraft has excessive bank, which when 'adjusted
for' results in the turn becoming flat and unbalanced, usually with the controls crossed.


The "illusion created by drift" can do that. This guy wasn't intending to skid the airplane, but he did and it killed him.

As an instructor I had occasion to teach this. https://www.tc.gc.ca/eng/civilaviation/publications/tp975-partii-ex20-5287.htm

Dan has a good point here, but that happened 15 years ago and the airplane has been refined since then. That was one of the very early models. I would be interested to know if there are any other Slepcev Storch crashes.....for any reason anywhere in the world during the last 15 years. One thing I find troubling about the report above is that like many accident investigations, it features conclusions and suppositions. I realize that not all investigations produce accurate answers as to why something occurred, and they do the best they can under the circumstances. What I find confusing in this report is that the investigator concluded ""... this accident exhibited all the factors consistent with a stall spin situation, resulting from a down wind turn at a low height. This occurs as a result of the pilot getting visual cues that convince the pilot that the aircraft has excessive bank(In this case is that a known fact or an educated guess about what happened ?), which when 'adjusted for' results in the turn becoming flat and unbalanced, usually with the controls crossed."

So it seems that for some reason the pilot " had visual cues of excessive bank" and simply concluded that the pilot tried unsuccessfully to level or flatten the turn and stalled. How does someone have excessive bank if they are doing a flat turn? Sounds like a lot of conclusions based on "this accident exhibited all the factors consistant with a stall spin situation" which I am guessing means he was moving slowly, turning, and obviously lost lift and stalled and spun in. Then based on his "experience" concluded that he had cross controlled during the turn . I'm still drawn to the comment about how he knows the pilot got visual cues he was overbanking and how the overbanking then became a flat turn, and the comment "which when adjusted for" which is a supposition, not necessarily a known fact. One thing occurs to me since the pilot was flying level and slow over a ranch to monitor his stock, could the investigator have ment that he was making a normal banked turn at a consistant altitude (flat) and then cross-controlled much like what happens to pilots making landings. That would seem more likely because of the reference to overbanking. Again, just guessing.

Its a good example Dan, but I find it a confusing explanation of events. I would like to know if there are any other examples of Slepcev Storch miscues on record, because we have all seen the videos demonstrating that it does work.
 
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BJC

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My airplane makes flat turns by applying full right rudder, full forward stick and full power. Of course, the descent rate is fairly high, so I don’t do that too low. Wing, perhaps, some day, you and I could find an S-2 and go for a ride. I’m certain that you would enjoy it. It might even be educational.


BJC

PS. You should have waited until the server was functioning properly before throwing gasoline on this smoldering fire.
 

BJC

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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
 

Winginit

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BJC

PS. You should have waited until the server was functioning properly before throwing gasoline on this smoldering fire.


Here is the thing BJC, its the end of the year and I would like to put all the animosity to rest and start the new year with everyone having a more positive outlook toward one another. I hope to make today, Dec 31 a point where we can all accept that while we each disagree with the others opinion, in the future it can be done simply with respect for what the other person says or believes. In the case of the Storch/ Flat turn debate, no one can deny that a Storch is perfectly capable of performing a flat turn in a very small radius, and can skid the tail to execute flat manuevers near the ground where wing bank is not an option. It simply can't be disputed that the Slepcev Storch CAN perform these manuevers because there are several videos demonstrating those things. (These things cannot be duplicated in the average certified or homebuilt and would prove to be life threatening)

So, since I think that no matter how much someone wants to deny the Slepcev Storches ability, at this point there is no way to deny that ability and the debate shifts to whether it serves a purpose, and whether or not it is dangerous (make that foolhardy). I attached an exerpt from an article when I started this thread where a well known (British) aviation pilot/journalist reviewed the airplane and raved about the controlability and the ability to easily perform flat turns. Again further proof of 1. capability and 2. ease of performance.

I'm going to attach another exerpt from another article where again a pilot performs flat turn manuevers with ease and the aviation journalist again raves about the controllability and ease of performing not just the flat turn but many other low altitude manuevers.

Flat Turn 8 001.jpg


What everyone now has to consider is that I have provided examples of several knowledgeable "experts" who have not only verified the airplanes capability, but the fact that it "easily" accomplishes them. Instead of this being just the "opinion" of someone like myself (who admittedly has never flown a Slepcev Storch....but wants to) vs the opinions of many other people who have no direct experience with a Slepcev Storch, we now have written opinions and actual flying experience documented by knowledgeable and respected pilot/journalists. The people with the "actual experience" support my opinion that not only can the SS perform the manuever, but it can perform it easily, repeatedly and safely.

Now I know that no matter what I post there will still be some people who won't like it, won't accept it, or at least reserve the right to doubt it. I'm ok with that. As I said, this is my "end of year" attempt to relieve old animosities and start the new year with renewed vigor. I have provided objective information and support for my views by other people with actual flight experience. I hope that many of you will at least reflect on what I have presented, even if it goes completely against the grain of everything you have been taught and experienced in other airplanes, and respect my opinion. I don't wish to pour gasoline on a smoldering fire, but rather consider it one last attempt to douse the flames with information that provides at least some food for thought.

With all of that being said, Its Dec 31, and I would like to wish EVERYONE on HBA a very happy and successful New Year.


New Year 2.jpg
 
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Tiger Tim

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But why? What makes a Slepcev Storch and only a Slepcev Storch capable of doing this? It's basically a Super Cub fuselage and tail hung off a high-wing Zenith wing and neither of those two airplanes are known for their uncanny ability to perform perfectly-safe-flat-turns-except-for-when-they-can't.
 

TFF

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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.
 

Turd Ferguson

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Its not breaking any laws of physics,

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.

I saw a real Fieseler Storch fly in 1980. I was impressed by what it could do based on the era in which it was designed. But like most other pilots, I have no interest in owning one, nor do I have any interest in owning a 75% scale version. Neither one has any sex appeal.
 
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choppergirl

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I seem to remember a Fokker Triplane could do a flat turn on a dime, making it a nasty opponent in a dogfight, if you're right at home riding on the back of the devil.

Probably the single most influential airplane that got me interested in aviation. I'd eat Camels in a flat turn all day long if I could.

When I first walked up to a full scale flying Fokker Triplane and Sopwith Camel in real life, I was like holy smokes are these things huge. They were 3/4ths that size in my imagination.

It still is disconcerting to me how big most airplanes are up close.

~

I always wondered, if you could install some jetisonable solid rockets on your tail, or under your wing, in a similar manner jets are used on an Apollo capsule to orient the spacecraft, that could kick your plane around in a flat turn, or hold your wing up when it loses lift, and then be jetisoned at the press of a button. Or maybe a tail rotor on your plane ala like a helicopter, that could quickly rotate your plane around on a dime. Absolutely no use to conventional aviation of getting from point A to point B in a straight line, but more of a tricky trick to be used in a tight dogfight, or since such things are obsolete... as an airshow stunt.
 
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Winginit

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But why? What makes a Slepcev Storch and only a Slepcev Storch capable of doing this? It's basically a Super Cub fuselage and tail hung off a high-wing Zenith wing and neither of those two airplanes are known for their uncanny ability to perform perfectly-safe-flat-turns-except-for-when-they-can't.

As with most things, the devil is in the details. The Slepcev Storch has no similarity to a Super Cub or even a Zenith STOL in its lineage other than both the Zenith and the SS have fixed slats on their wings. They use different airfoils, different wing loading, weight,length, wingspan etc. The SS is derived from the Fiesler Storch which was an advanced design observation airplane that was huge....yet it could do many things at very slow speeds. The SS is a derivitive of the original Fiesler design. It looks very similar but besides the 3/4 scale, there were some other differences/improvements incorporated. Every airplanes personality is the sum of all its details, making it different than even similiarly designed versions by other companies. I don't say that the SS is the only airplane that can perform this manuever. There may be other airplanes that can, or can come close...that would be something others would need to speculate on. The SS is, to the best of my knowledge the only airplane claiming they can do so and actively demonstrating it as part of their sales pitch.


Below is a video of a full size Fiesler Storch flying effortlessly at an air show. Notice that it seldom banks its wings or only minimally banks them thru most turns while gracefully floating along at airspeeds that most aircraft would drop from the sky...even when not turning. If memory serves me, the wingspan is a whopping 46 ft. Hope you enjoy the video and gain some appreciation for an outstanding historic airplane.

https://www.youtube.com/watch?v=ZZUHgcTldRM
 

pictsidhe

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Just because you can do something, doesn't mean that it is a good idea. Try a flat turn a little above stall and see just what physics makes of it. The Storch has an unusually low stall speed of 20kts, so it can do things that seem unusual, like fly with one wing only doing 20kts. It has a rectangular wing, that gives a bit more lift margin out at the tips that the tapered wing on a high speed optimised plane. It may be that by the time you have the inner wing about to stall, the descent rate has caused you to bottle out of the manoeuvre. But, stall a wingtip in a slow flat turn, you are going down. Hopefully, you did it with some spare altitude.
Ye cannae change the laws of physics, Jim!

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?
 

Turd Ferguson

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This is disguised discussion about turn rate and radius. A slow airplane can turn at a greater rate with a smaller radius with very small amounts of bank which contribute to the perception of turning while in a wings level attitude. A plane comes by at 300 kts and it appears to be hardly turning despite being banked at 45 degree. Which one is safer? Is there any data?
 

BBerson

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The flat turn was popular in Europe until 1908 when Wilbur Wright demonstrated superior banked turns. Flat turns are for boats.
Brief history of flat turns here:
https://books.google.com/books? id=...YAhVT4GMKHfPFDwcQ6AEIYjAR#v=onepage&q&f=false
 

Turd Ferguson

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The flat turn was popular in Europe until 1908 when Wilbur Wright demonstrated banked turns. Flat turns are for boats.

My speedboat banks when it turns unless it's at idle speed. Not much of a speedboat if drive it around at idle all the time.

At the end of the day, turns that require minimal angles of bank require corresponding low level of fwd velocity. Not many people want a plane so they can fly slower than a moped.
 

BBerson

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My speedboat banks when it turns unless it's at idle speed. Not much of a speedboat if drive it around at idle all the time.

At the end of the day, turns that require minimal angles of bank require corresponding low level of fwd velocity. Not many people want a plane so they can fly slower than a moped.
Yeah, it depends on forward speed. In a hover, my quad copter can yaw turn 180° instantly. But with forward motion it also needs considerable bank to reverse course.
 

Tiger Tim

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As with most things, the devil is in the details.
Of course, but what details? The SS is a fabric-covered, skinny, slab-sided, tandem seat fuselage hung under a wing with slats and no dihedral and I'd bet almost no washout. Where does the magic hide?
 
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