Search found 16 matches

by DanielBednar
Fri Jul 24, 2020 8:05 pm
Forum: Technical/Operations
Topic: 737 Electrical System Questions
Replies: 6
Views: 1274

737 Electrical System Questions

Hey guys, a couple questions about 73 electrics: 1) If you look at the schematic, TR 3 has a diode located between it and its DC buses that are operated in parallel with the other TR’s. What’s the point of the diode there, and why do TR 1 & 2 not have one? 2) When operating under a single genera...

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by DanielBednar
Fri May 01, 2020 2:29 am
Forum: Technical/Operations
Topic: N1/N2 RPM question
Replies: 3
Views: 1080

N1/N2 RPM question

Hello all, N1 and N2 are driven by separate shafts and are mechanically independent of each other, allowing them to have different rotational speeds because they are on different shafts. But why is N1 significantly slower (5,000 RPM) compared to the N2 RPM (15,000 RPM)? Does N2 need to rotate faster...

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by DanielBednar
Wed Mar 04, 2020 3:08 am
Forum: Technical/Operations
Topic: L1011-250 Payload Range
Replies: 15
Views: 3742

Re: L1011-250 Payload Range

https://m.youtube.com/watch?v=geWRUKCoyZ8&t=3s
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If you’re looking for a really enjoyable L1011 video, check out the following link to my channel’s video. Taken in 1986 when my father was a flight engineer on the L1011.

https://m.youtube.com/watch?v=geWRUKCoyZ8&t=3s

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by DanielBednar
Fri Aug 09, 2019 2:49 am
Forum: Technical/Operations
Topic: Hydraulic reservoir pressurization/ cavitation?
Replies: 22
Views: 3250

Re: Hydraulic reservoir pressurization/ cavitation?

Okay, so basically, just as high altitudes and low pressures are harmful for humans, the same can be said for pumps. At low pressures, cavitation will cause bubbles to form in the fluid at the pump inlet which can be harmful. So they put bleed air inside to pressurize so that cavitation won’t happen...

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by DanielBednar
Fri Aug 09, 2019 1:17 am
Forum: Technical/Operations
Topic: Hydraulic reservoir pressurization/ cavitation?
Replies: 22
Views: 3250

Re: Hydraulic reservoir pressurization/ cavitation?

Thanks guys, another follow-up question. I’ve heard the term “hydraulic head pressure” mentioned a lot while trying to get an answer to this question. What does that mean? Thanks again

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by DanielBednar
Thu Aug 08, 2019 4:19 pm
Forum: Technical/Operations
Topic: Hydraulic reservoir pressurization/ cavitation?
Replies: 22
Views: 3250

Hydraulic reservoir pressurization/ cavitation?

Hello, Why is the hydraulic reservoir pressurized by bleed air? I’ve read it’s to reduce the probability of cavitation and fluid foaming at high altitudes and low pressures. But what is cavitation and why does it happen? Why would pressurization help with that? And what does foam have to do with it?...

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by DanielBednar
Fri Aug 02, 2019 8:52 pm
Forum: Technical/Operations
Topic: High pressure hydraulics vs bleed air
Replies: 15
Views: 3009

Re: High pressure hydraulics vs bleed air

Thanks guys.

Starlionblue wrote:
BTW hydraulics are up to 5000PSI in newere aircraft.


What difference would it make? Does 5,000 as opposed to 3,000 have major performance differences?

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by DanielBednar
Fri Aug 02, 2019 5:49 pm
Forum: Technical/Operations
Topic: High pressure hydraulics vs bleed air
Replies: 15
Views: 3009

High pressure hydraulics vs bleed air

We always talk about how the bleed air we use is VERY high pressure, but it’s nothing compared to the 3,000 psi hydraulic systems. Would it be possible to have a pneumatic system that is pressurized to 3,000 like the hydraulics. I assume there wouldn’t be any benefits and there’s no way engines coul...

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by DanielBednar
Tue Jul 30, 2019 8:26 pm
Forum: Military Aviation & Space Flight
Topic: Apollo CSM EPS “fuel cell heaters”
Replies: 0
Views: 2412

Apollo CSM EPS “fuel cell heaters”

Hello,

In the Apollo CSM, there are switches for “fuel cell heaters” do these control the pre-heaters for the O2 and H2 or something different? Thanks

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by DanielBednar
Thu Jul 25, 2019 3:38 pm
Forum: Technical/Operations
Topic: Bleed air stages?
Replies: 3
Views: 1526

Bleed air stages?

Hello,

I know that bleed air comes from two stages of the compressor. What I’m wondering is whether one is in the low pressure compressor and the other in the high pressure compressor, or if both are in the high pressure compressor but one is a lower stage than the other but still in the HPC. Thanks!

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by DanielBednar
Mon Jul 22, 2019 9:25 pm
Forum: Technical/Operations
Topic: Pack/air cycle machine
Replies: 4
Views: 3058

Pack/air cycle machine

Hello - the following is something I’m going to post on Wikipedia but I want verification that my post is correct. Here it is: An air cycle machine, part of an aircraft’s air conditioning pack (pressurization and air conditioning kit) utilizes hot pressurized bleed air from the high pressure compres...

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by DanielBednar
Thu Jul 18, 2019 8:02 pm
Forum: Technical/Operations
Topic: Recirc Fans/ engine start
Replies: 9
Views: 2397

Recirc Fans/ engine start

Hello,

When the packs are off for engine start, are the recirculating fans recirculating any air through the cabin to provide some amount of airflow?

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by DanielBednar
Wed Jul 17, 2019 10:01 pm
Forum: Technical/Operations
Topic: Fuel & Oil characteristics and qualities
Replies: 1
Views: 949

Fuel & Oil characteristics and qualities

Hello,

I’m wondering what specific characteristics should engine fuel and oil have for jets, that makes kerosene based Jet A/A1 so useful. I believe the freezing point of the fuel has something to Dow it’s it, but what else?? Thanks.

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by DanielBednar
Wed Jul 17, 2019 6:47 pm
Forum: Technical/Operations
Topic: Combustor, Burner Cans, etc.
Replies: 3
Views: 1324

Combustor, Burner Cans, etc.

Hello,

I’m wondering how the combustor of a jet engine on a MODERN airliner works, and how the burner cans relate to it, and just overall how it works. Also, when fuel is added to the engine, is it in liquid or gas form? Thanks.

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by DanielBednar
Tue Jul 09, 2019 6:52 pm
Forum: Aviation Hobby
Topic: (RARE!) Eastern Airlines Lockheed L-1011 Footage (Exterior, Cabin, Galley, Flight Deck)
Replies: 5
Views: 3553

(RARE!) Eastern Airlines Lockheed L-1011 Footage (Exterior, Cabin, Galley, Flight Deck)

https://www.youtube.com/watch?v=geWRUKCoyZ8&feature=youtu.be I found this video inside my closet and it was taken by my dad, who was an Eastern Airlines Flight Engineer, way back in 1986. I decided to post the L-1011 TriStar footage on Youtube in the hopes that it will bring nostalgia to some pe...

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by DanielBednar
Sat Jul 06, 2019 1:13 am
Forum: Technical/Operations
Topic: 777 Cabin Temperature Controllers (CTC)
Replies: 1
Views: 1340

777 Cabin Temperature Controllers (CTC)

Hello, I’m wondering what the function of the CTC is. I’ve heard it mentioned before and it does something to control the A/C system, but I’m not sure what. Does it modulate the pack valves, control trim air, or something else? Thanks all!

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