Posts by user "MechEngr" [Posts: 6 Total up-votes: 0 Pages: 1]

MechEngr
June 22, 2025, 01:56:00 GMT
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Post: 11908221
Originally Posted by JustusW
if ( happy == true ) {
print("I'm happy!"
}
It has 2 bugs. 3 if one expects anything to show up on a terminal, at least it used to be the case that print statements were buffered until encountering \n or \r. The first two problems would be caught by most compilers. Fortunately all three will beat up a programmer pretty good in the first day or two so they stop doing that.

Over on reddit in /r/FPGA there are numerous complaints of tools producing incorrect outputs for FPGA and the observation that one cannot examine the state of an FPGA while it is operating; simulators are OK, but cannot reproduce slight timing variation related problems. At least with C one can, relatively easily, match 1:1 non-optimized compiled assembler output to the original input to see if the compiler is translating things correctly.

I expect FPGA if used are used for initial signal processing rather than logic. One can check that the processing is stable with signal generators and noise injection. The decision part is much more readable in C or Ada for people to decide if the logic is right and the test cases available can be used to verify that the compiler/linker is working OK, plus the aforementioned direct examination of the intermediate results, plus active debuggers to examine the state of the more conventional microprocessor.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): Generators/Alternators

MechEngr
June 22, 2025, 02:46:00 GMT
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Post: 11908248
Wood is a composite material. It might be a good match in the coefficient of thermal expansion to the carbon/epoxy composite and cheaper than making the fixture from carbon/epoxy composite, which would have itself required a support.

Subjects: None

MechEngr
June 29, 2025, 20:40:00 GMT
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Post: 11913217
There are a lot of cameras in the world to record where pieces were found and in what condition and orientation. Concerns might be raised if the cleanup was with bulldozers and backhoes, but I would not expect that in this case. Additionally, a very important and relatively recent tool - the high-resolution camera-carrying multiblade drone can capture the entire debris field in a few hours of a single day. While I don't know if it would help, even thermal infrared camera-carrying drones are widely available and relatively cheap to better distinguish details that might be obscured in normal illumination.

Were this a crash into a forest, where trees would make over-view photography difficult, speed of collection might make a difference, but I think it is mainly open sky where additional photography can be done as layers of building debris are removed.

Last edited by MechEngr; 29th June 2025 at 21:50 . Reason: took out comma.

Subjects: None

MechEngr
July 11, 2025, 23:48:00 GMT
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Post: 11920016
Originally Posted by Engineless
A douple-pole switch. One pole used for FDR signal for the physcial switch position. The other pole for the electrical switching circuit.
It could be done that way, but the secondary contact and wiring could fail and, unless a continuous power circuit was used to ensure that there wasn't a break, the digital recorder might not get coordinated information. This would also end up extended to all other switches making for a major increased in wiring and an increase in the number of channels for the FDR.

Small cameras capturing all the switches on each panel would be sufficient and make for a tiny increase in the amount of wiring while capturing not only the events with the switches, but also any actions of the crew, intentional or accidental.

Like, intending to push a button, but it was accidentally pushed an insufficient amount to engage, that sort of thing. For a few bucks more, a motion analysis module could decide what button or selection is being made, compare to the result to see if there is some problem, and/or generate an alert in response to operation outside of typical practice.

Since the effect of the state of the switches is usually immediate, the amount of recorded video need only be a few minutes. Example - it is unlikely that a switch that was in one position, moved, and then moved back, will have an effect that is only noticed 5 hours later. If the switch is put in the wrong position, then it will remain in the wrong position until it is moved, even if that wrong position causes an incident hours or days later, at which time it will still be on the video recording.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): FDR

MechEngr
July 12, 2025, 03:47:00 GMT
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Post: 11920152
Originally Posted by LTC8K6
Such a fault in a multi pole switch would be odd. And in two switches at roughly the same time?
Typically you'd have a fault in one set of poles, giving you conflicting data.
Such as the EAFR registers a fuel switch in cutoff, but the fuel did not actually cut off.

Don't forget that the RAT deployed instantly, shortly after liftoff, agreeing that both switches were in CUTOFF.
Yes - conflicting data issuing a warning when the system being controlled has no fault. That's a problem at considerable expense for a rare occurrence.

Literally covering all the bases with a video would not only show what the switch status was but also how it got there, if it has an immediate effect, which a second line would not do.

Subjects (links are to this post in the relevant subject page so that this post can be seen in context): EAFR  Fuel (All)  Fuel Cutoff Switches  RAT (All)  RAT (Deployment)  RUN/CUTOFF

MechEngr
July 14, 2025, 19:36:00 GMT
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Post: 11922446
Originally Posted by Gupeg
There is a huge difference between Starlink letting the SLF watch videos and WhatsApp their mates, and using it to stream regulated data... in the latter case, once mandated, whenever Starlink has a glitch, or cannot logon, the flight is grounded.
Of the 5 flights I have done where the carrier advertises me a sort of WiFi service, on 3 it has never worked, one I got to send a few messages then no more and on one it was sort of useful, some of the time...
The proposal is to -also- stream to Starlink or the equivalent. No need for grounding for an optional accident investigation data stream that in no way affects safety of flight.

Carriers advertise all sorts of things. They tend to deliver on the transportation one with everything else optional to varying degrees.

Subjects: None