New start material strenght calculation for operating horn from crashed plane. Part 2 4

[RedSnake]

Can anyone help me check if this calculation works so far?
There are so many conversions between different units ..
The calculation is made by a free software but I assume that their calculation models are correct.

My own assumption is that the elevator is heavier at the front edge as there are hinges made of MIL 1430 N and since the lever and its attachment also are , there are also steel details on the other side and the rest is aluminum.
I have chosen to see it as a simple bar to begin with.

And the calculation is made to check which load the fixed joint must withstand for the elevator's own weight.

I intend to present it in steps so if I got something wrong I can adjust it before the next step.
If it's okay with you people?

Best regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

The gps position is broadcast by

https://en.wikipedia.org/wiki/Automatic_Dependent_Surveillance–Broadcast#

You can get your own receiver to receive it at home if you want. The aircraft just blindly puts out data even when there is nothing to receive it.

Secondary sends out a pulse of radar with an instruction to send me your data, the transponder then sends back the data from a pinpoint source.

primary blasts out loads of power and then try's to see the reflections coming back.

 

[RedSnake]

Alistair
I do think you explained this somewhere, that if the plane becomes heavier at the rear, you do have to compensate with the elevator while trimming in the stabilizer is that correct?
And if so, will there be more pressure on the elevator then while doing so ?
And if you also increase the speed at the same time?

By the way, is there anything I can help you with as a thanks for you putting up with all my questions?
Maybe I can draw a circuit diagram for your main power station or something?
Haven't got a propper program for it but I think I can fix it anyway..

Best regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

yes it is correct its just a force balance.

Most aircraft require a force on the tail downwards in cruise so by shifting the weight to the rear you actually reduce the load on the elevator.

As you increase the speed the amount of lift the tail generates increases so you have to change the trim just as you would with any other increase in speed to balance the force balance.

The range of the force and when the aircraft crosses the line and becomes statically and dynamically unstable I don't know, protection against that happening is staying inside the CoG envelope.

 

[RedSnake]

Alistair do you have any films on regular stall exercises?
Like the ones you linked to for spins?
And is a dive angel of 14 degress normal when flying and not making a landing ?

Best Regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

14 degrees for a jump plane is not extreme.

The thing that limits is usually engine cooling. You can shock cool these petrol engines and do serious damage by going from high power down to idle suddenly. Turbine engines don't have the same issues and go down much faster and not worry. In fact they usually are on the ground before the jumpers.

To be honesty there is not any difference with stalling to those spin videos initially only thing different is the stall they control the yaw and lower the nose again and everything back to normal.

 

[RedSnake]

I realized last night that the plane probably stalled before it went really wrong but the pilot fixed it, as he should have done.
Then today I received an email from the 2 older gentlemen with a document that they sent to SHK to day with their version of what happened.
And when I read what they wrote, they had come to the same conclusion ..
But after that we do not agree.
I will explain more later.
Must go and do some errands before the weekend.

Best regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[rb1957]

Man ! I'm surprised by this thread. Someone is trying to solve an air accident with folks on Eng-Tips !

I guess all credit to Anna for finding and pursuing this course. It's amazing to me that we're the best source available, and I guess that's to our credit.

Anna, the thread is TL and DR. Are you with an air accident investigation organisation ?

another day in paradise, or is paradise one day closer ?

 

[Alistair_Heaton]

Anna's partner was a fatality in the accident. There is another thread which gives you the lead in with how the conversation developed.

https://www.havkom.se/assets/reports/RL2020_08e-Final-report.pdf

 

[RedSnake]

Thanks Alistair for jumping in and explaining.

It's amazing to me that we're the best source available, and I guess that's to our credit.

Both yes and no, I don't know if this is the best source available, but that does not matter.
I found this page and got stuck so I did not look further, everyone is so nice and helpful.
There is not so many I know who I can discuss this with.
I really just wanted to calculate the material strength but then this thread has gone all both here and there.
Trying to keep it in check is like wrestling with an annaconda. LOL
Even though I prefer facts, I probably think a little bit too much outside the box to be on a page where there are only specialist.
And since I myself am not a specialist in this subject, it probably suits me better.
My experience is that, the more diffrent angles of approach, the better the results.

Anna, the thread is TL and DR.

But I will nead to get an explanation of the above, all these abbreviations. sigh ;-)

Best regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[davidbeach]

Too Long
Didn't Read

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[RedSnake]

davidbeach
What was to long and what didn't you read ?

Best regards A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[MacGyverS2000]

david was defining the acronyms TL and DR for you... often seen as "TL/DR".

Dan - Owner

http://www.Hi-TecDesigns.com

 

[RedSnake]

LOL Okey Thanks LOL
Sorry davidbeach ..

Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[RedSnake]

What I was thinking about was.
If the plane falls 30 m in 4 seconds at angel 14 degrees and a little more before he managed to catch up.
I think the plane must have stalled..
In that movie where they practice spins, it takes about 5-6 sec before he manages to start getting upp again .
Do not know of course, how far the plane had fallen then?
But something that falls in free fall, falls 30 m in 2.5 sec.
The manual states that the plane can fall in the worst case 90 m, 300 feet in a stall.
And the plane also changes course a bit to the left in this point 12:06:38.

So is this a "normal" stall "forward" or not ?

Best regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

its almost certain it stalled at some point.

Google secondary stall, I have to go to work for 12 hours.

 

[RedSnake]

I have been a good girl, as it is called here in Sweden, when we do as we are told ;-).
And I have check out what you suggested online.

Stolen with pride, is also something we say at work when we reuse something that is well done.

The pilot must also understand how the factors that affect stalls are interrelated. In a power-off stall, for instance, the cues (buffeting, shaking) are less noticeable than in the power-on stall. In the power-off, 1G stall, the predominant cue may be the elevator control position (full up elevator against the stops) and a high descent rate.

Add thrust/power. Power should be added as needed, as stalls can occur at high power or low power settings, or at high airspeeds or low airspeeds. Advance the throttle promptly, but smoothly, as needed while using rudder and elevator controls to stop any yawing motion and prevent any undesirable pitching motion. Adding power typically reduces the loss of altitude during a stall recovery, but it does not eliminate a stall. The reduction in AOA is imperative. For propeller-driven airplanes, power application increases the airflow around the wing, assisting in stall recovery.

My conclusion is that at the first stall the pilot did according to the "book".
But to find out what happened next, if it was a second stall (have read about that too).
Then the first assumption that the above is a actuall stall must be correct, otherwise there can not be a "second stall" ?! ???

So is it? Any one?

But if I am now going to speculate, then can anyone tell me if any of the following statements, read assumptions are completely up the walls?

• The plane stalls "forward" about 14:06:38
• And turns slightly to the left.
• The angle of the aircraft is the first 4 seconds about 14 degrees nose down.
• The plane falls 30 meters in 4 seconds.
• And then 8 more before it flattens out.
• To raise the stall, pull the "steering wheel" towards you, to get the elevetor max up, to reduce the nose down and get the nose up until the plane flattens out.
• Then the pilot recovers from the stall about 14:06:46 and then comes up to the height again (4145m) at 14:06:54.
• 14 degrees is not a "giant" slope downwards, but since the jumpers sit with their backs in the direction of travel, it is difficult to "stay" in place.
• Those sitting at the back may have moved a little forward when the plane puts its nose down 14 degrees.
• When the pilot recovers the stall and the plane is on its way up again about 7 degrees nos up, it is easier to stay in the same position because you can hold on with your feet and hands, so not to slide backwards again.
• Which may have meant that the plane's center ogf gravity was a little further back before this stall than it was after at 14:06:54 (The center of gravity was moved a bit forward).
• If the plane has just come out of a stall, it is more natural for the pilot to tell the jumpers to move forward.
• Or that the jumpers themselves move forward because that is what they "think" they should do after other instructions after stall warnings.
• That the jumpers would not start moving backwards again directly after the stall was recovered and the plane reached it's height again.

Feel free to comment ..

BR A.



“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

At some point they must a have been going either fast enough to cause structural failure or pull enough G for structural failure.

There are multiple ways this could have happened being so far outside CoG envelope.

Any turns tends to mean that the yaw was not under control. If the yaw is not under control a spin results.

 

[RedSnake]

At some point they must a have been going either fast enough to cause structural failure or pull enough G for structural failure.
Yes thats true.
But the plane didn't fall appart/brake until at least around a minute later.

But the lever for the elevator may have broken off here if he had to put the elevator towards the maximum stop.
And know, I'm not saying it did, it's probably not likely, I just want to be able to make the calculation so I can rule it out.
And let it go :-(

There are multiple ways this could have happened being so far outside CoG envelope
Also true, but right now I am just looking at these 20 seconds.
Trying to analys everthing at ones, is too much for my brain to handle :-(
One step at the time..
There is another teori that can not be proven, as with that CoG was outside the envople and which I mentioned earlier is not correct with what was writen in the type certificat,
and that is that the pilot pulled the lever towards himself when he tried to find the switch for the lighting that he would light a minute before of the jump would take place.
It sits in a roof panel diagonally up to the right of the roof, it has apparently happened before but then it was with a copilot so then it went well,
now I do not know if it was the same pilot as now, I want to be clear with that.
And he should have done that around the time the plane stalled for the first time.

Any turns tends to mean that the yaw was not under control. If the yaw is not under control a spin results.
Yes, but this happened before the plane turned, and I agree with you But not according to the to older gents, they know that it made a steep dive not a spin .. or

But the plane did not deviate in these stall so this was not the CoG problem then he would not have managed to get out of it in the first position, I think, But you must have practiced stalls more then ones, so do you but elevator at the maxstopp up when recovering ?

Hope you hade a nice day at work..

Time for bed now..

Best regards A



“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[Alistair_Heaton]

Thing is a 30 meter drop in 8 seconds isn't that much or in fact unusual.

Its about 700-800ft per min which is what we do as standard while doing a 3 degree approach to land. During a stall I would expect 2-3000ft per min decent rates, Which even then are not that unusual I was doing 4500 ft/min yesterday to help air traffic out separating us against an outbound.

I have never hit he elevator max stop. The only time I could even imagine being able to do it in the air is during a spin when it has no load on it. And as a flying instructor we were doing stalling every week at least once spinning monthly.

 

[RedSnake]

According to CP and SHK, this is done at every single landing?
Just before touch down?
I have also seen it on film but thats besides the point here.

The first 4 second where 30 m 14 degrees.
Since the secondary radar only pings every 4 seconds, the curve should be rounder and the angle probably steeper at the beginning.
That plane is, as I understand it quit slow and dosile.
So if he haden't recovered it in time you would have hade a max velosity 3000 feet/min.
Or?

Free fall

Fall in 4 seconds.

Best regards Anna

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein