Light plane crash, Serpentine airfield, near Perth, WA.

[facthunter]

Pen name, If you are applying a lot of back pressure you are at risk of getting a high ROD and stressing the plane or flick rolling it in the turn. . None of this is a good idea. UNLESS you do it with a qualified pilot/instructor in a very strong plane with plenty of air underneath you to cover all possibilities.  Nev

[turboplanner]

2 hours ago, Jerry_Atrick said:

Let's make sure we let the ATSB do their stuff. I don't want to stifle the conversation on generalties of these situations as we always learn a lot. I just want people to know we do not make any judgement, as we don't yet really  know what happened.

Going back to the accident, we have bull's information, and there may have been other witnesses who don't realise they have critical information and will come forward in time.

 

However, for your information ATSB don't normally investigate Recreational Aviation accidents, unless for a specific reason, when they announce they will investigate, so unless you see ATSB advise (not the press or a local club member) that they are sending people to the scene of an accident, don't expect any information from them.

 

What usuallu happens for RA accidents is the local State Police investigate it as an accident, and if they need any technical advice for their brief to the Coroner they'll ask for RAA to send an investigator to provide specialist advice (sometimes RAA will call ASTB specialists in. The Police brief is sealed and the forst thing we see is a Coroner's Report.

 

So for this accident we would be looking for a Coroner's report in a few months time.

[marshallarts]

19 minutes ago, turboplanner said:

However, for your information ATSB don't normally investigate Recreational Aviation accidents, unless for a specific reason, when they announce they will investigate, so unless you see ATSB advise (not the press or a local club member) that they are sending people to the scene of an accident, don't expect any information from them.

What makes it a Recreational Aviation accident?  Just the registration of the aircraft?  If so, this one wasn't an RA incident - the aircraft is/was VH registered.

Edited December 30, 2020 by marshallarts

[turboplanner]

31 minutes ago, marshallarts said:

What makes it a Recreational Aviation accident?  Just the registration of the aircraft?  If so, this one wasn't an RA incident - the aircraft is/was VH registered.

OK, sorry, I didn't do enough checking. In that case Jerry is correct, There will be an ATSB prelim report soon. 

[APenNameAndThatA]

2 hours ago, facthunter said:

Pen name, If you are applying a lot of back pressure you are at risk of getting a high ROD and stressing the plane or flick rolling it in the turn. . None of this is a good idea. UNLESS you do it with a qualified pilot/instructor in a very strong plane with plenty of air underneath you to cover all possibilities.  Nev

That's how come I stopped.

[facthunter]

Yes. I sort of gathered that. Good move. There MUST be some way of getting the right experience if you really wanted to. There's some pretty radical ways of doing quick course reversals, but I'm not going into that here. Nev

[Mike Borgelt]

OK people what does the elevator do?

[Mike Borgelt]

BTW, the ATSB is about as much use as mammaries on a male cow.

[Jerry_Atrick]

That may be the case, but they are ones who are investigating the specifics of the accident and will provide the authorative report.

 

7 hours ago, turboplanner said:

Going back to the accident, we have bull's information, and there may have been other witnesses who don't realise they have critical information and will come forward in time.

That is my point. Often, those who are emotionally raw will do an internet search to find information to help them make sense of their loss. That search may bring them to this thread. They may or may not have any flying experience. My post was to point out to those in this sad situation who may be reading this that the conversation had morphed into the generalities of limitiations of the flight envelope based on what would be credible but not necessarily complete information of the cause of the accident. Therefore, nothing specifically should be drawn from it about the accident.

 

It was also to point out that despite our training, which teaches us not to do many stupid things, our experience, and ongooing learning from those who have trodden the path before us, that we are fallable and can make mistakes.

 

I did mention in my post that, "I don't want to stifle the conversation on generalties of these situations as we always learn a lot."

 

[edit]@Turbs - this wasn't specifically referencing you; it was a general point as I think a few have misinterpreted the reason for my post [/edit]

Edited December 30, 2020 by Jerry_Atrick

[Blueadventures]

10 hours ago, Mike Borgelt said:

I think you'll find that you have this the wrong way round. Stopping the prop will reduce drag. A windmilling engine is absorbing energy. Next time you fly do an aborted takeoff with plenty of room to stop easily on the runway. Note the deceleration when you close the throttle.

Motorgliders like the Xenos in glide mode will stop the prop for this reason. Also if in an aircraft with constant speed prop, go to full coarse pitch if you can do so if the engine stops. In traveling type motorgliders with variable pitch props feather mode is an extreme example which completely stops the prop easily.

Additional info is that an engine at idle will result in forward movement to a degree.  Therefore the difference between engine at idle and stopped will be different that there is more drag prop stopped than turning at engine idle. Been there and done it. To see difference land at a long strip engine on idle, land, don’t apply any braking; will keep rolling img along and speed demonising very slowly, you will most likely over run an airstrip that is say 3.5 times you braked landing roll distance. While rolling switch off engine and now your speed will decay rapidly. This is worth a practice even for a loss of brakes situation senecio so that you know any time no brakes presents, immediately consider turning engine off to assist stopping if obstacles or if no remaining runway is presenting. I’m not an instructor so not intending to offer instruction.  I did this situation when I found my brakes not normal on feel check during downwind and lined up on final at required speed an did not use brakes to see what would occur. I was flying a Skyranger Nynja, landed at 48 knots, available runway 700 meters, Ashfelt, normally turn off at under 200 meters, at 400 meters decided to stop engine as rolling good and not loosing speed. Cheers.

[Garfly]

58 minutes ago, Mike Borgelt said:

OK people what does the elevator do?

Turn the aircraft?

[spacesailor]

Elevator  !! ELEVATES THE AIRCRAFT? LoL.

spacesailor

[bull]

18 hours ago, turboplanner said:

Going back to the accident, we have bull's information, and there may have been other witnesses who don't realise they have critical information and will come forward in time.

 

However, for your information ATSB don't normally investigate Recreational Aviation accidents, unless for a specific reason, when they announce they will investigate, so unless you see ATSB advise (not the press or a local club member) that they are sending people to the scene of an accident, don't expect any information from them.

 

What usuallu happens for RA accidents is the local State Police investigate it as an accident, and if they need any technical advice for their brief to the Coroner they'll ask for RAA to send an investigator to provide specialist advice (sometimes RAA will call ASTB specialists in. The Police brief is sealed and the forst thing we see is a Coroner's Report.

 

So for this accident we would be looking for a Coroner's report in a few months time.

This was a VH accident

 

[turboplanner]

20 minutes ago, bull said:

This was a VH accident

 

Yes marshallarts mentioned that too. He'll at least get a very thorough analysis to find all the details of what happened

 

[M61A1]

20 hours ago, APenNameAndThatA said:

After I have cut power and waited three seconds, my speed drops to about 45 kt

The whole idea of training for this event is to do away with the delay. It has been an issue in several crashes I have read about, where the pilot did exactly as they practiced in a real emergency with a bad result.

In any case if you ae more than a couple of hours into your training, changing the AoA with varying thrust should be pretty much instinctive. Meaning that as the power comes off (doesn't matter whether it's because you reduced it of it failed), you automatically maintain the correct AoA for safe flight.

I believe that any instructor that teaches you to wait to do anything  after power failure may be unwittingly setting you up for failure.

Practice what you will actually do.

 

[FlyBoy1960]

okay naysayers, I checked my sources with a quick phone call last night and can give you real figures regarding flying with the engine at idle flying with the engine stopped

 

The Pipistrel Sinus airframe with the engine stopped and the propeller unfeathered has a sink rate of around 210 ft/m, with the propeller feathered 187 ft/m

 

The Pipistrel Sinus airframe with the engine at idle has a sink rate of 90 ft/m and of course this is why the aircraft must use both flaps and airbrakes for a normal landing with the engine at idle otherwise it sits in ground effect for more than 1000 m before it will slow enough to settle.

 

As demonstrated by these figures with the engine stopped the sink rate is around double of what it is with the engine at idle, and this is the point I was trying to make.

 

People practice "engine failed landings" but still have the engine at idle will therefore have a performance which is significantly better than it is with the engine stopped.

 

Regardless of what creates more drag has nothing to do with what we are talking about, we are talking about sink rate, what will get you to the ground fastest and that is definitely stopped engine.

 

Again, I am not the expert I'm just repeating parrot fashion the information from a two times NASA/CAFE challenge winner pilot and one time team owner winner who does know what he is talking about.  (provided I have understood him correctly)

So in summary, if we practice dead stick landings with the engine at idle we are going to get better performance both in sink rate and distance than we are with the engine  stopped. The point I was trying to make through all of these comments is that you can practice with the engine at idle as much as you want BUT when the engine is stopped there is going to be a deep crease in performance which may/can/does catch out many experienced pilots because the sink rate is significantly less and turning is not helped by those extra 15 hp of the engine at idle pulling you through a turn back to the runway. The message here is, unless you have KNOWN performance of your aircraft sorted out or you have an excessive height beyond what you think you can get away with than just land straight ahead

[Mike Borgelt]

You need to differentiate between "engine stopped" i.e prop isn't turning and "engine stopped" with fuel and/or ignition turned off and prop windmilling. Try it in the Sinus next time

Might also help if you the idle RPM set correctly on your engine first.

Also the effect of the engine idling at low speeds on landing roll will be different from the much higher speed in the glide. Clearly it produces nett thrust in the low speed case.

 

[Mike Borgelt]

I tried the engine failure after takeoff in the BD-4 case at a safe altitude not so long ago. There is a very bad tendency to pull the stick back to limit the rate at which the nose drops. When I deliberately closed the throttle AND DID NOT MOVE THE STICK the aircraft was in no danger of stalling and established a safe glide speed.

 

Which leads me to "what does the elevator do?"

 

The answer is - it controls the angle of attack of the wing. As the elevator is directly connected to the stick the POSITION (NOT FORCE which depends on trim setting) of the stick controls the angle of attack of the wing Assumes statically stable aircraft with mechanical or hydraulic control connection, not FBW or relaxed stability types like F-16 or when you load the aircraft so the C of G is back well past the aft limit) . All else follows from this. If you don't want to stall DON'T PULL THE STICK BACK SO FAR. Unfortunately teaching of stalling generally ignores this and so far nobody has produced a simple device to indicate elevator position to the pilot although it is on my "to do" list. It is a good thing if the control system in your aircraft is geared  so that the top of the stick moves a long way fore and aft. According to aero engineer Stan Hall (designer of the Cherokee 2 sailplane amongst other things) designing a control system this way will cause most pilots to rate the aircraft as "easy to fly" even when there are other shortcomings.

There is a discussion hereon windmilling propellers: https://aviation.stackexchange.com/questions/64394/does-a-windmilling-propeller-create-more-drag-than-a-stopped-propeller-in-an-eng

[Mike Borgelt]

There is a discussion here on windmilling propellers: https://aviation.stackexchange.com/questions/64394/does-a-windmilling-propeller-create-more-drag-than-a-stopped-propeller-in-an-eng

some of which appears to be sensible.

For other references  search Google for "drag windmilling propeller"

 

There some different engine failure cases to consider.

 

Engine seizes and prop stops

Engine not producing power due ignition or fuel failure

Engine not producing power due gearbox or clutch failure on a Rotax 912 but prop windmills

Engine not producing power due prop departing aircraft

[Jim McDowall]

The November 2020 issue of EAA Sport Pilot had an excellent article on this subject which in summary is that if your glide angle is less than your climb angle dont even think about turning back. The article referenced FAA Advisory Circular AC 61-83J para A.11.4:

 A.11.4 Return to Field/Engine Failure on Takeoff. Flight instructors should demonstrate and teach trainees when and how to make a safe 180-degree turnback to the field after an engine failure. Instructors should also train pilots of single-engine airplanes not to make an emergency 180-degree turnback to the field after a failure unless altitude, best glide requirements, and pilot skill allow for a safe return. This emergency procedure training should occur at a safe altitude and should only be taught as a simulated engine-out exercise. A critical part of conducting this training is for the flight instructor to be fully aware of the need for diligence, the need to perform this maneuver properly, and the need to avoid any potential for an accelerated stall in the turn.

(emphasis added)

 

[FlyBoy1960]

this is where we are getting confused I think we are not talking  DRAG  we are talking sink rate.

 

An aircraft with a propeller turning at idle will create more drag than a stopped propeller but the sink rate of the engine at idle will be less.

 

My comments were about a stall spin occurrence and it is much more likely to happen with the engine stopped completely than it is with the engine at idle and possibly producing around 15 hp.

 

From what I am told it is impossible to windmill a propeller attached to a Rotax engine because of the gearbox, it may roll over a compression once every now and again but it is not an issue like direct drive.

 

So in summary, it is much easier to stall and spin with the engine stopped completely than it is with the engine at idle and producing roughly 15 hp.

 

The sink rate is less with an engine at idle because it is producing some thrust from the 15 hp.

 

This was why I made the comments that I did as part of the discussion, not to excite people into debate just to think about it a little bit more and it could hopefully/possibly affect a result in the future.

 

We can practice engine off landings with the engine at idle but it is going to give you a better "performance" result than it will with the engine stopped so you need to be prepared for reduced performance when the engine actually stops.

 

The same person gave me all of this information also told me the following which has never left my memory in years.

 

"I thought he was a pretty good pilot until I started flying a motorglider and this just proved how little I really knew. It was only when I actually learnt how to glide that I then became a good pilot."   

 

I think that is pretty close to Word for Word but it made me think that every pilot license should have at least a couple of hours  of gliding as part of the training package because every aircraft without an engine will become a glider, that is guaranteed !

[facthunter]

The rpm ,pitch and airspeed determine whether you have thrust or not. Just because an idling motor will prolong the ground run doesn't extend to it providing thrust when the plane's going faster.   It has some resemblance to the gearing of any vehicle, in that respect.. When any engine is IDLING it's very close to actually stopping just before each cylinder fires. The actual horsepower it's making is miniscule. The slightest load on it and it stalls. Nev

[APenNameAndThatA]

31 minutes ago, facthunter said:

The rpm ,pitch and airspeed determine whether you have thrust or not. Just because an idling motor will prolong the ground run doesn't extend to it providing thrust when the plane's going faster.   It has some resemblance to the gearing of any vehicle, in that respect.. When any engine is IDLING it's very close to actually stopping just before each cylinder fires. The actual horsepower it's making is miniscule. The slightest load on it and it stalls. Nev

This does seem to be the truth of it. I had been thinking that an idling engine provided least drag (because power from engine), then stopped prop providing next least drag (stalled prop), then windmilling prop providing the most drag (because the prop is using the gravitational potential energy of the plane to turn the engine over.) But, if an aircraft is going really fast, an idling prop will provide more drag than a stopped prop, because the air is turning the prop rather than the prop providing any thrust at all. 

[APenNameAndThatA]

13 hours ago, spacesailor said:

Elevator  !! ELEVATES THE AIRCRAFT? LoL.

spacesailor

The elevator turns and elevates the aircraft. More accurately, in coordinated flight, the elevator controls the angle of attack of the wing, and the wing turns and elevates the aircraft. When the aircraft is banked, the horisontal component of lift turns the aircraft and the vertical component of lift elevates the aircraft.

 

The rudder does not turn the aircraft at all in coordinated flight because the rudder acts at right angles to the direction of acceleration of the aircraft. The rudder has to act at right angles to the direction of acceleration of an aircraft in coordinated flight, because the ball is in the middle! (Turning an aircraft is acceleration because turning means a change in velocity. Velocity is defined in terms of speed and direction.)

[APenNameAndThatA]

2 hours ago, FlyBoy1960 said:

okay naysayers, I checked my sources with a quick phone call last night and can give you real figures regarding flying with the engine at idle flying with the engine stopped

 

The Pipistrel Sinus airframe with the engine stopped and the propeller unfeathered has a sink rate of around 210 ft/m, with the propeller feathered 187 ft/m

 

The Pipistrel Sinus airframe with the engine at idle has a sink rate of 90 ft/m and of course this is why the aircraft must use both flaps and airbrakes for a normal landing with the engine at idle otherwise it sits in ground effect for more than 1000 m before it will slow enough to settle.

 

As demonstrated by these figures with the engine stopped the sink rate is around double of what it is with the engine at idle, and this is the point I was trying to make.

 

People practice "engine failed landings" but still have the engine at idle will therefore have a performance which is significantly better than it is with the engine stopped.

 

Regardless of what creates more drag has nothing to do with what we are talking about, we are talking about sink rate, what will get you to the ground fastest and that is definitely stopped engine.

 

Again, I am not the expert I'm just repeating parrot fashion the information from a two times NASA/CAFE challenge winner pilot and one time team owner winner who does know what he is talking about.  (provided I have understood him correctly)

So in summary, if we practice dead stick landings with the engine at idle we are going to get better performance both in sink rate and distance than we are with the engine  stopped. The point I was trying to make through all of these comments is that you can practice with the engine at idle as much as you want BUT when the engine is stopped there is going to be a deep crease in performance which may/can/does catch out many experienced pilots because the sink rate is significantly less and turning is not helped by those extra 15 hp of the engine at idle pulling you through a turn back to the runway. The message here is, unless you have KNOWN performance of your aircraft sorted out or you have an excessive height beyond what you think you can get away with than just land straight ahead

This might be the most important post ever. It means that we are all practicing forced landings wrongly, and should be banking on twice the rate of descent than we get when we are practicing forced landings. That means that when we are practicing forced landings, we should be half as far from the field. It also means that in an actual forced landing, our turns would need to be tighter and *our nose would need to be much lower*.

 

Maybe, what it means is that we should practice forced landings with full flaps, and that in the even of an engine failure, we should expect the same performance with half or no flaps.

 

Maybe, the reason that people spin when they are trying to return to the airfield is not that they try to stretch the glide, but that they use the same view through windscreen as they are used to, when, in fact, they need the nose much lower than they have ever had it in the past!