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Search: Posts Made By: silverstrata
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Forum: Rumours & News
4th Dec 2018, 11:12
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

I think MCAS was a rudimentary attempt to prevent...

I think MCAS was a rudimentary attempt to prevent a stall developing.

When at high angles of attack, the 2.5 degrees of forward stab trim would apply control column pressure, and thus urge the...
Forum: Rumours & News
3rd Dec 2018, 11:12
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Sorry, MCAS has little or nothing to do with...

Sorry, MCAS has little or nothing to do with longitudinal stability, and everything to do with stall avoidance. That is why it monitors AoA, and operates at high AoA angles (ie: at the stall). The...
Forum: Rumours & News
2nd Dec 2018, 15:09
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

It matters not if that rear surface on the...

It matters not if that rear surface on the Trident is an elevator, a balance-tab, or a servo-tab - the same choice applies.

Do you fit the anti-stall aumentation system to the control column,...
Forum: Rumours & News
2nd Dec 2018, 08:38
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

The Trident had a T-tail and possible elevator...

The Trident had a T-tail and possible elevator blanking.
The 737 has a large nose up moment from underslung engines.

They each have a design issue at the stall that requires an anti-stall...
Forum: Rumours & News
1st Dec 2018, 20:16
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Yes, sorry, my bad. Apparently the fault was...

Yes, sorry, my bad. Apparently the fault was recognised in early flight testing back in ‘62, when the Trident entered a flat spin and refused to recover. (See Bartelski, ‘Disasters in the Air’...
Forum: Rumours & News
1st Dec 2018, 19:21
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

No, it is not as simple as that. A stick pusher...

No, it is not as simple as that. A stick pusher should be required on all aircraft that do not have a natural nose down response, at the stall. And there are many of those. It should not be simply up...
Forum: Rumours & News
1st Dec 2018, 18:32
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

The 737 can go vertical nose-up at the stall, due...

The 737 can go vertical nose-up at the stall, due to engine thrust/lift moments. As was amply demonstrated at Bournemouth, when a stalling -300 series pitched 44 degrees nose up, as speed continued...
Forum: Rumours & News
1st Dec 2018, 12:28
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

A high speed stall is not the same, as the...

A high speed stall is not the same, as the elevator will still have a lot of authority at those higher speeds. MCAS was designed for a slow speed stall, when engine thrust combined with engine...
Forum: Rumours & News
30th Nov 2018, 20:25
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

The MCAS system was not designed for 250 kts, it...

The MCAS system was not designed for 250 kts, it was designed for low speed upsets near the stall. And those events normally (but not exclusively) take place near to sea level. So Boeing would...
Forum: Rumours & News
30th Nov 2018, 07:55
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

The -400 had 24,000 lb thrust. The -800 had...

The -400 had 24,000 lb thrust.
The -800 had 27,000 lb thrust.
The max-8 has 28,000 lb thrust.

I call that a steady increase in thrust, with a steady increase in pitch up moment, when...
Forum: Rumours & News
29th Nov 2018, 08:07
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

And the engines are much more powerful - up to 30...

And the engines are much more powerful - up to 30 k lb of thrust. All that extra thrust, low down on the airframe, generates a large pitch up moment - especially if the aircraft is slow and the...
Forum: Rumours & News
29th Nov 2018, 08:02
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Manual trimming. Edit: Yes, manual trimming...

Manual trimming.

Edit: Yes, manual trimming with the trim wheel only shows up as trim position, not as trim input. So at the end of the previous flight, they were spinning the big wheel around by...
Forum: Rumours & News
25th Nov 2018, 20:46
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Indeed, that was the thrust of my argument. The...

Indeed, that was the thrust of my argument. The 727 grandfather-heritage resulted in the original 737 having slim engines tucked in close to the wing, which gave very little engine induced nose up...
Forum: Rumours & News
25th Nov 2018, 11:04
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Oh, MCAS has many famous granparents. ......

Oh, MCAS has many famous granparents.

... It had a 727 with rear engines, that allowed the gear to be short and the wing low.
... Then the 737 antique, with the same short gear low wing...
Forum: Rumours & News
24th Nov 2018, 11:02
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Some random observations. On the previous...

Some random observations.

On the previous flight they disconnected the stab trim system, which stopped the MCAS inputs. So it is possible to use the trim cutout switches on this system. They then...
Forum: Rumours & News
15th Nov 2018, 20:44
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

From day one of flight school we are taught to...

From day one of flight school we are taught to fly the stick, and only use trim to take out stick-loads. And never to fly the trimmer. (And that slides across to the 737, even though its...
Forum: Rumours & News
15th Nov 2018, 19:39
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Another problem with these larger engines, is...

Another problem with these larger engines, is that they are more powerful, and I presume their center of thrust is lower on the airframe (because of the larger N1 fan diameter). Both of which result...
Forum: Rumours & News
15th Nov 2018, 02:44
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Nomad ... we left UAS behind some 20 pages ago. ...

Nomad ... we left UAS behind some 20 pages ago.
This incident is likely nothing to do with UAS.
Please read some back-pages.

Silver
Forum: Rumours & News
15th Nov 2018, 02:25
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

What Boeing were trying to guard against with...

What Boeing were trying to guard against with MCAS, is a repetition of the Sept 2007 pitch up event at Bournemouth, where a 737 pitched to 44 degrees nose up during a stall event. This happened...
Forum: Rumours & News
14th Nov 2018, 15:49
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

One imagines that the stick-shaker might also...

One imagines that the stick-shaker might also operate (there is no stall alert-tone or warning-lamp). Depends how close to the stall this stall-trimmer system starts to operate. Other than that, I...
Forum: Rumours & News
14th Nov 2018, 15:34
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Which is why you want a stick push, rather than a...

Which is why you want a stick push, rather than a stall trim.

A pusher can give you full stick forward, but as soon as you reach flying speed it will relent and give you normal control with normal...
Forum: Rumours & News
14th Nov 2018, 15:26
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Disagree entirely, the mighty stab trim can...

Disagree entirely, the mighty stab trim can overpower the piddling elevator.
Especially if you were on the front of the flight envelope to start with.
Have you ever tried giving max nose down trim...
Forum: Rumours & News
14th Nov 2018, 15:17
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Ah, well that clears up the small mystery. ...

Ah, well that clears up the small mystery.
The Classic has 17 units of trim, which equates very nicely to your 17 degrees of trim.

Silver.
Forum: Rumours & News
14th Nov 2018, 10:38
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Good point. The trim sheet has: Indexes,...

Good point.

The trim sheet has: Indexes, MACs, and Units. The FCOM has Units. Nowhere that I can see mentions trim degrees. If Boeing is quoting real degrees here, and not trim units, then that is...
Forum: Rumours & News
14th Nov 2018, 10:23
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

From the FCOM (737 classic). OMB ll 9.20.9. ...

From the FCOM (737 classic). OMB ll 9.20.9. STS requires 60% N1 before operation.
I presume that limits STS to the climb.

Silver
Forum: Rumours & News
14th Nov 2018, 09:26
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

That is a 737 colloquialism, using ’degrees’ in...

That is a 737 colloquialism, using ’degrees’ in the generic sense - eveyone says ‘degrees’ but we mean ‘units’. As you say, they are not real degrees - you would have to look on the trim-sheet to see...
Forum: Rumours & News
14th Nov 2018, 09:14
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

I wish you would all stop this angle of attack...

I wish you would all stop this angle of attack nonsense. You are all confusing fuselage pitch-angle (on the PFD) and the wing angle (which can be changed with the rigging angle). Of course you...
Forum: Rumours & News
14th Nov 2018, 09:04
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

[/i][/b] That seems a lot of trim to me. ...

[/i][/b]

That seems a lot of trim to me. Try flying at 5,000 and 250 kt, and then mis-trimming forward by 2.5 degrees. You will be struggling.

Strikes me that Boeing designed this stall-trim...
Forum: Rumours & News
14th Nov 2018, 08:44
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

The STS normally trims nose down after take-off. ...

The STS normally trims nose down after take-off.
It is safer that way....

Silver
Forum: Rumours & News
13th Nov 2018, 20:38
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Ok, I did not know the Max has a new stall...

Ok, I did not know the Max has a new stall assistance system. As mentioned before, the STS normally trims down after take off, so it would be operating in the same manner as the new stall system. ...
Forum: Rumours & News
13th Nov 2018, 15:51
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

How do you know this is a genuine fault? The 737...

How do you know this is a genuine fault? The 737 STS system ALWAYS trims the wrong way - that is what it is ‘suposed’ to do. And the pilot response on every flight is to trim back the right way -...
Forum: Rumours & News
5th Nov 2018, 07:56
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

Except that the B737 has no computers. The flight...

Except that the B737 has no computers. The flight control system and STS system is good old 1961 engineering - whacking great 5mm steel cables to all control surfaces, plus a bit of hydraulic servo....
Forum: Rumours & News
4th Nov 2018, 17:37
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

The term ‘computer’ is somewhat overstating the...

The term ‘computer’ is somewhat overstating the technology in the speed-trim system. It is a couple of 286 processors, based upon a Sinclair ZX Spectrum architecture.

Silver
Forum: Rumours & News
1st Nov 2018, 16:36
Replies: 2,099
Views: 1,471,854
Posted By silverstrata

CWS is still there on the NG, but have never seen...

CWS is still there on the NG, but have never seen anyone use it, in decades of flying. Most absurd system ever invented.

A bit like the 737 eyebrow windows, which have never been used by anyone...
Showing results 1 to 34 of 34


 
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