Aircraft down Lancefield Vic

[pmccarthy]

I have never been in flat spin, althoughI have done ordinary spins. I phoned an aerobatic instructor after reading these posts to enquire how to get out of a flat spin. He told me you let go of the stick, pull the throttle completely closed and keep the rudder pedals centred. He said if you have any engine input you can't get out of the flat spin as the engine continues to enhance the spin. I was told that if I followed flat spin instructions, the aeroplane would fly itself out of the spin and the pilot then could resume control. I have certainly learned something from reading these posts.

I asked the same question yesterday if an experienced aerobatic pilot and he told me flat spin recovery includes full into-spin aileron, get it to roll into a dive, then recover.

 

 

[dutchroll]

Can anybody confirm that is correct? as it does not sound right to me.

That instructor seems to have quoted a non-standard technique, especially in respect of holding rudder neutral. That's not going to achieve anything at all for many aircraft types in a spin.

It seems to me rather unwise to use a hybrid or non-standard technique for spin recovery unless that is the technique specifically listed in the POH, as determined by spin testing that aircraft design. For example, if you're flying an aircraft where the POH says that spin recovery is just neutralising all controls that's fine (there are some which will actually recover all by themselves if you basically take the pilot out of the equation!). Try to do that in a Chipmunk or a Pitts and you'll be sitting there with neutral controls until you impact the ground.

 

 

[djpacro]

I asked the same question yesterday if an experienced aerobatic pilot and he told me flat spin recovery includes full into-spin aileron, get it to roll into a dive, then recover.

Yep, for many types but for some inspin aileron flattens it with delayed or nil recovery.

[facthunter]

You can't be sure if the quote is correct, but we don't need this nonsense out there about spin recovery. It differs with many aircraft and you should know YOURS if you are going to put out information.. Just because someone is an instructor doesn't mean the statement is set in concrete either. There aren't that many aircraft out there that are spun, or many pilots who are fully knowing of all of it.. If I was da king I would have ALL instructors trained and capable of recovering from spins. You may never know what happened with this aircraft. (Why it did what it did). Nev

 

 

[Oscar]

I am NOT an experienced power-plane pilot, though I've done plenty of conventional spins in gliders - but I have been taught about the aerodynamic details fairly thoroughly, and I believe that any 'generic' advice is quite possibly potentialy dangerous.

 

What causes a spin to flatten, is basically centrifugal force (many here will have seen Facthunter's frequent references to the fact that adding ballast may keep an aircraft within its CoG limits but may also add inertia to the spin which could have bad / disastrous effects). If the rear effective area is insufficient to keep the speed of rotation down, an unrecoverable flat spin may develop.

 

Effective rear area is why you see large dorsal and ventral fins on some aircraft. Blanking of the fin area from a 'conventional' fin and elevators arrangement, is a feature of many designs ( it's why the Jabiru, for instance, has the elevators set very well back relative to the fin). Even the big boys get this wrong sometimes: if you look at the evolution of the Cessna 162 design, (which had I think two cases of unrecoverable spins in its early days)? - you'll see how much change there was to the tail-feather configuration. Those sexy thin rounded tailcone designs exacerbate the lack of effective tail area: the older, 'slab-sided, with square edges' designs were FAR more effective in anti-spin aerodynamics. Some swept-back fins just place almost all of the fin and rudder in the blanked area.

 

This is why all proper spin testing is done with a spin-chute (or other recovery devices, but the chutes have proven to be the most reliable WHEN they are properly designed). The FTSA paper I referenced above, may be published soon on the FTSA site which is currently being upgraded; it's a rather good read. Amongst other things, it explains the problems for the Whitney Boomerang gaining full acceptance as a Utility Category aircraft - and if you look at the Boomerang, it seemed to have everything going for it (and Bill Whitney is a very, very experienced designer).

 

Having satisfactorily completed the spin matrix for Normal Category (one turn only) the next phase was to investigate Utility Category spins. On the first 2 turn spin the aircraft entered an un-recoverable mode. Application of various control and power combinations had no influence on aircraft motion and the chute was deployed at the soft floor. The chute was felt and seen to deploy, but had no influence on aircraft motion. The only influence the test pilot was able to achieve was small pitch attitude changes with fore and aft stick inputs. Recovery was achieved just before the hard floor by out of phase pitch inputs which eventually un-stalled the wing and allowed a conventional recovery from the resultant spiral dive mode. At this stage all attempts at investigating potential for Utility Category certification were terminated.

 

So: I believe that it is very, very dangerous to assume that a recovery technique that may work with a particular aircraft, should be assumed to work for even something that appears to be similar. Again, I suggest, that if someone with Keith Engelsman's experience, can find himself with no other option than to pull the spin-chute, he's tried everything he knows - and that is likely to be more than just about anybody else in the game. Extrapolating an Instructor's advice that may well be entirely correct for a specific aircraft, to be correct for every aircraft, may well got you killed. And, if you are flying an aircraft that is materially different in weight distribution to that tested in certification/certifying, even the certificated/certified results, may not be applicable.

 

 

[jakej]

If some posters knew of DJP's background they would be embarassed by their posts, he is one guy you SHOULD take notice of when it comes to aeros & aerodynamics.

 

 

[shafs64]

Sorry I should of said do not try this in your aircraft its just an example of a spin.

 

this might help.

[Oscar]

With respect, I don't think that WAS a fully-developed flat spin. And, an Extra 300 is hardly your average LSA...

 

 

[Yenn]

I doubt that many pilots do a weight and balance check whenever they fly.

 

Most will know that unless they add non normal loads to some part of their plane that it will be within limits.

 

I would not check unless I had luggage in the aft locker and a low fuel load, because I know that it would be practicaly impossible to be out of limits otherwise.

 

 

[DonRamsay]

I've done the calculations for my Sling in every balance situation - within POH limits. That is, as long as you don't exceed 600kg total and you don't exceed the 35kg baggage and you have at least the minimum weight pilot (never my problem) you can't exceed POH acceptable balance range. Did the same calcs for a Tecnam Sierra with the same result. My recommendation is that you should do those calcs for the plane you fly and understand the results.

 

Biggest risk comes when somebody changes the original config - not a problem with an LSA or type cert factory built - or doesn't respect the laws of physics as illustrated in the POH.

 

 

[djpacro]

With respect, I don't think that WAS a fully-developed flat spin. ...

I think it was.

[jakej]

Oscar, I did post a warning:celebrate: DJP may want to pitch in here but the ASI is the give away ie it's not increasing in the turns & ball is off centre while thats all happening - pretty basic really

 

Fullscreen display is better.

 

 

[Oscar]

DJP and Jake: Sirs, I bow to your knowledge. Probably, I am using old references from gliding, where a normal spin is not (normally) very nose-down.

 

 

[jakej]

Sir ? - I think you are referring to DJP.

 

 

[Oscar]

My apologies, Ma'am, if so your are, but Sir does me for males who I respect..

 

 

[SDQDI]

DJP and Jake: Sirs, I bow to your knowledge. Probably, I am using old references from gliding, where a normal spin is not (normally) very nose-down.

? I'm no spinning expert, actually have never done one (would like to, with a competent instructor of course!) but I thought normal spins were nose down?

In the video the plane does 2 turns in a nose down attitude which I would regard as a spin and then once the controls were manipulated flattened the attitude into what I would consider a flattish spin? Is my assumptions correct or am I way out?

 

After seeing how little I knew when I started my ll training I would love to do an unusual attitudes course as IMO the more I know how dodgy I am the more careful I am likely to be.

 

 

[jakej]

[Ultralights]

, why was the aircraft clearly witnessed spiralling all the way to the ground, .

first lesson in aircraft investigation techniques, is.. never trust a witness report.

 

 

[jamel]

Oscar the spins I experienced when I was learning gliding were fully developed spins and I can assure you I was looking straight at the deck and turning like a top! The old instructor must have sensed I wasn't too keen on the idea and made me wait for at least 3 revolutions before I was allowed to recover it! To this day I haven't let an aircraft past the incipient stage, and i hope I never do!!!

 

 

[jakej]

FYI - spiralling is identified by an increasing airspeed. That does not happen in a fully developed spin in the aircraft we mostly fly.

 

 

[facthunter]

The FIRST thing you must do is identify ..Spin or Spiral. The turn needle will show direction (and rate sometimes) The indicated airspeed.... Increasing..... You are in a spiral.

 

Steady or slightly fluctuating near stall you are spinning.

 

The spiral will impose steadily increasing loads which will eventually overload the structure. The spin does not do that. The airframe loads are moderate until the pull out from the dive, where you may see just under 3G if you do it correctly.. Nev

 

 

[jamel]

FYI - spiralling is identified by an increasing airspeed. That does not happen in a fully developed spin in the aircraft we mostly fly.

Thanks , I learn something new every day! It was many years ago but I think it was Va speed he drummed into me not to exceed on recovery? Hated every second of it! and as you say the things I fly now are very different, but that training certainly served its purpose.

 

 

[dutchroll]

? I'm no spinning expert, actually have never done one (would like to, with a competent instructor of course!) but I thought normal spins were nose down?In the video the plane does 2 turns in a nose down attitude which I would regard as a spin and then once the controls were manipulated flattened the attitude into what I would consider a flattish spin? Is my assumptions correct or am I way out?

Yes a conventional spin is a fairly nose-low attitude and this is exactly what he had by turn 2 after it had passed through the incipient phase. It appeared to me that he went into a flat accelerated spin by applying opposite aileron and forward stick while still having the "into spin" rudder applied, and flattened it by adding power. All typical effects. Pulling the power off steepened it again and he recovered.

As a general rule you need a nose down attitude for recovery because it is in that attitude that you can get the most rudder effectiveness to oppose the yaw. When spinning in a flat attitude the airflow over the rudder is shielded by the horizontal stabiliser. Adding or reducing power changes the gyroscopics.

 

first lesson in aircraft investigation techniques, is.. never trust a witness report.

I take your point there, but a "spiralling" aircraft is fairly hard to mistake, although some witnesses may say it was "tumbling". Some types of eyewitness reports can be unreliable, eg, whether the aircraft was right way up or upside down is something most wouldn't be able to accurately distinguish. However when more than one says they saw it "spiralling", it was probably spiralling (I don't mean necessarily spiral-diving, I mean just going round and round). And again, the impact photo tells a lot too. No scattered wreckage, no scrape marks indicating it skidded or careered into the field. Just what's left of a plane as if it had been slapped straight down in that spot from above. Hard to imagine any other scenario.......

 

 

[cooperplace]

If a spin theory doesn't seem likely, why was the aircraft clearly witnessed spiralling all the way to the ground, and why did it impact with low forward velocity? It's not like wreckage is strewn across a wide area with big scrape marks across the ground - it's all in one little spot.There are any number of ways it might have entered into it and any number of reasons why it might not have recovered, but it's the only scenario (I believe) which fits the fairly clear description of spiralling, how it seems to have impacted, and a failure to recover to controlled flight.

yes, concur with you there.

 

 

[Ultralights]

I take your point there, but a "spiralling" aircraft is fairly hard to mistake, although some witnesses may say it was "tumbling". Some types of eyewitness reports can be unreliable, eg, whether the aircraft was right way up or upside down is something most wouldn't be able to accurately distinguish. However when more than one says they saw it "spiralling", it was probably spiralling (I don't mean necessarily spiral-diving, I mean just going round and round). And again, the impact photo tells a lot too. No scattered wreckage, no scrape marks indicating it skidded or careered into the field. Just what's left of a plane as if it had been slapped straight down in that spot from above. Hard to imagine any other scenario.......

i would think, if it was a spiral dive, with ever increasing airspeed, it would impact at high speed, destroying pretty much everything, or everything up to the leading edge of the wing, as seen in some aircraft after crashing stright down, whereas a pancake type landing, as what looks like could have happened looks more like a spin, hitting the ground with no forward airspeed, and only motion being the rate of descent at impact.