grumpyoldgeek
2025-06-15T02:05:00
permalink Post: 11902051

Quote:

Originally Posted by Xeptu

It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight)

I've read your cite four times and could not find anything implying that " a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected." I guess you need to explain it to me like I was eight.

Subjects: Gear Retraction V1

grumpyoldgeek
2025-06-15T21:49:00
permalink Post: 11902876

RAT and best glide

Firstly. I find all the speculation about hearing the RAT suspect. Not that I doubt observers heard something sounding like a RAT, but that I question the fidelity of the low bit rate and bit depth of the audio to reproduce the difference between the sound of a deployed or non-deployed RAT. The audio sounds quite distorted and I have zero confidence that anyone could accurately tell. Secondly, is the speculation about best glide performance. Any private pilot knows that best glide does not exist until the pilot pitches the nose down and establishes it. As far as I can see, there is no time nor visible indication that the nose pitched down. What I see is the aircraft mushing down to the ground with the nose high and just short of a stall.

Subjects: RAT (All)

1 user liked this post.

grumpyoldgeek
2025-06-16T00:51:00
permalink Post: 11903014

Quote:

Originally Posted by boeing_eng

I've ground tested countless RAT's on 757/767's over many years....

Having just watched (or more importantly listened to) the latest video by Captain Steeeve on YT, I'm fully confident the deployed RAT can be heard

Not trying to be a smart ass, but how do you "ground test" a RAT?

Subjects: RAT (All) RAT (Deployment)

grumpyoldgeek
2025-06-16T00:51:00
permalink Post: 11903733

Quote:

Originally Posted by boeing_eng

Not trying to be a smart ass, but how do you "ground test" a RAT?

Subjects: RAT (All) RAT (Deployment)

grumpyoldgeek
2025-06-19T18:47:00
permalink Post: 11906262

Has it been determined from the wreckage that the RAT was deployed at the time of impact?

Subjects: RAT (All) RAT (Deployment)

grumpyoldgeek
2025-06-19T23:59:00
permalink Post: 11906498

Quote:

Originally Posted by MatthiasC172

Can someone help me with the calculations on how far from the point of our last ADS-B readout we can expect the stricken jet to fly/glide?

I am assuming the take off mass around 190-200 tons with 50 tons of fuel. For the glide phase this is of no importance, however.

Data on the Internet puts the glide ratio of a 789 around 18-21:1. Gear and flaps/slats out should have a significant negative effect. Does anyone have a good take how much? Minus 40%?

From the available data we can infer the plane never was higher than 200\x92 AAL, maybe even 100\x92. If I understood the online sources correctly, the point of impact was only about 20\x92 lower than the average runway level.

If I am not mistaken the distance from the last ADS-B point to the impact site is about 2 km as per Reuters and the Guardian. That would put it at 6,500\x92.

I just can\x92t get these numbers over each other without the aircraft producing thrust. Please help me correcting the numbers.

Best glide performance doesn't start until the pilot pitches the nose down and establishes best glide. As near as I can see, the nose never pitches down.

Subjects: ADSB

2 users liked this post.

grumpyoldgeek
2025-06-26T21:58:00
permalink Post: 11911531

Quote:

Originally Posted by D Bru

Thx, this indicates at least two issues:

1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss;
2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake.

Regards,
D Bru

I have to disagree with point 1. They did not give a reason for using the front unit and I don't see why you would assume one.

Subjects: CVR EAFR RIPS

3 users liked this post.

grumpyoldgeek 2025-06-15T02:05:00 permalink Post: 11902051	Quote: Originally Posted by Xeptu It's been troubling a few of us for some time. To translate all that for the layperson, a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected.(in flight) I've read your cite four times and could not find anything implying that " a momentary electrical event triggered at V1 (still on the ground) and restored after rotation before gear up is selected." I guess you need to explain it to me like I was eight. Subjects: Gear Retraction V1
grumpyoldgeek 2025-06-15T21:49:00 permalink Post: 11902876	RAT and best glide Firstly. I find all the speculation about hearing the RAT suspect. Not that I doubt observers heard something sounding like a RAT, but that I question the fidelity of the low bit rate and bit depth of the audio to reproduce the difference between the sound of a deployed or non-deployed RAT. The audio sounds quite distorted and I have zero confidence that anyone could accurately tell. Secondly, is the speculation about best glide performance. Any private pilot knows that best glide does not exist until the pilot pitches the nose down and establishes it. As far as I can see, there is no time nor visible indication that the nose pitched down. What I see is the aircraft mushing down to the ground with the nose high and just short of a stall. Subjects: RAT (All) 1 user liked this post.
grumpyoldgeek 2025-06-16T00:51:00 permalink Post: 11903014	Quote: Originally Posted by boeing_eng I've ground tested countless RAT's on 757/767's over many years.... Having just watched (or more importantly listened to) the latest video by Captain Steeeve on YT, I'm fully confident the deployed RAT can be heard Not trying to be a smart ass, but how do you "ground test" a RAT? Subjects: RAT (All) RAT (Deployment)
grumpyoldgeek 2025-06-16T00:51:00 permalink Post: 11903733	Quote: Originally Posted by boeing_eng I've ground tested countless RAT's on 757/767's over many years.... Having just watched (or more importantly listened to) the latest video by Captain Steeeve on YT, I'm fully confident the deployed RAT can be heard Not trying to be a smart ass, but how do you "ground test" a RAT? Subjects: RAT (All) RAT (Deployment)
grumpyoldgeek 2025-06-19T18:47:00 permalink Post: 11906262	Has it been determined from the wreckage that the RAT was deployed at the time of impact? Subjects: RAT (All) RAT (Deployment)
grumpyoldgeek 2025-06-19T23:59:00 permalink Post: 11906498	Quote: Originally Posted by MatthiasC172 Can someone help me with the calculations on how far from the point of our last ADS-B readout we can expect the stricken jet to fly/glide? I am assuming the take off mass around 190-200 tons with 50 tons of fuel. For the glide phase this is of no importance, however. Data on the Internet puts the glide ratio of a 789 around 18-21:1. Gear and flaps/slats out should have a significant negative effect. Does anyone have a good take how much? Minus 40%? From the available data we can infer the plane never was higher than 200\x92 AAL, maybe even 100\x92. If I understood the online sources correctly, the point of impact was only about 20\x92 lower than the average runway level. If I am not mistaken the distance from the last ADS-B point to the impact site is about 2 km as per Reuters and the Guardian. That would put it at 6,500\x92. I just can\x92t get these numbers over each other without the aircraft producing thrust. Please help me correcting the numbers. Best glide performance doesn't start until the pilot pitches the nose down and establishes best glide. As near as I can see, the nose never pitches down. Subjects: ADSB 2 users liked this post.
grumpyoldgeek 2025-06-26T21:58:00 permalink Post: 11911531	Quote: Originally Posted by D Bru Thx, this indicates at least two issues: 1. The investigation's reliance on the front RIPS battery backuped EAFR indicates a confirmation of a total electrical power loss; 2. Earlier reports (i.e. AVH, now removed) of successful readout of and observations from CVR have proven outright fake. Regards, D Bru I have to disagree with point 1. They did not give a reason for using the front unit and I don't see why you would assume one. Subjects: CVR EAFR RIPS 3 users liked this post.

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