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access-air
Topic Author
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BAC-111 Startup Sounds!

Tue Mar 26, 2002 12:28 pm

Can anyone please tell me the reason why, in the BAC-111 series 400 and 500, other than engine mark number, why they make the air-raide siren sound during engine startup and the 200 series does not??? I have not heard a 300 series. What component is on the series 400/500 engine that makes that very distinctive sound....Also did the heavier Trident 3s make this same sound upon startup???? I have also noted that on the Gulfstream series Bizjets that the Speys do not make that sound either.....

Some BAC-111 experts or RR Spey Experts please???

Access-Air
Remember, Wherever you go, there you are!!!!
 
VC-10
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RE: BAC-111 Startup Sounds!

Wed Mar 27, 2002 3:51 am

Firstly the Spey 506 (200 series a/c) & the Spey 512 (500 series a/c) have identical start systems.

The engine is turned for engine start through the Constant Speed Drive & Starter (CSDS). As you may know a CSD is used to maintain Generator RPM constant throughout the engine speed range. In the CSDS this is achieved though an epicyclic differential gear coupled to a reversable air motor

In the diag below engine N2 is fed into the CSDS through the input shaft and via the sun & planet gears drives the generator. If the engine is at low speed, HP bleed air is fed, via a Air Control Valve (ACV), to the air motor which will rotate and add speed to the gear system, thus increasing the output speed to the generator. As Engine gearbox output RPM approaches the generator's required 6,000 rpm the ACV will progressivly close thus reducing the amount of speed the air motor adds to the gear train.

If the engine is at high power the torque reaction of the generator will start to drive the air motor backwards thus making it an air pump. Now, as the engine RPM is too high for the generator, input speed has to be removed. This is done by the ACV again, using the air motor as a brake. As mentioned, at high engine speed the air motor acts as a pump so by controlling the exhaust area of the pump you control it's speed by balancing the pressure rise across the motor to maintain air motor speed sufficient to balance the generator torque.




Now to the point of your question.

During the start sequence air is fed to the air motor which then drives the gear train via the planet carrier gear of the diffential and the engaged sprag clutch to the output drive gear. This double input provides an overall fixed speed ratio between the air motor and the engine. As the generator reaches its synchronous speed of 6,000 RPM the air motor will be rotating at 12,000 rpm, while the engine's HP section will be doing 5,000 rpm (40% N2)

The air-raid siren is the air motor. A long winded way of getting to the point but I think if I had just said it's the air motor it woudn't have made sense.

Trident's & other Spey powered a/c have conventional starter motors.

Incidentally I worked on 1-11's (200, 400 & 500's) for many years and never noticed and difference in the noise they made during start. If you notice any difference it may be due to the condition of the CSDS silencer that was fitted in the cowlings.

 
access-air
Topic Author
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RE: BAC-111 Startup Sounds!

Wed Mar 27, 2002 10:15 am

Thank you for the explanation.
It all makes sense but im still befuddled as to why the 400 and 500 series aircraft the engines on them make thats sound..but the 200 does not.....I have recently flown on a 500 series and I flew back in 1989 on a 200 series and the two sound completely different. As well i have also heard from the outside only, a 400 series and they make they same sound as the 500.....So im just wondering if its a different air starter motor for the lower thrust engines on the 200 series....ive recently listened to both my 500 series flight reocrding and my 200 series recording and they are diff....oh well..Thank you for the info..It helped me  Smile

Access-Air
Remember, Wherever you go, there you are!!!!
 
VC-10
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RE: BAC-111 Startup Sounds!

Wed Mar 27, 2002 10:21 am

Were the cowling open or closed? With the cowlings open the air doesn't pass through the silencer.

From what I can remember it was the same part number CSDS on the 200 & 500
 
access-air
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RE: BAC-111 Startup Sounds!

Wed Mar 27, 2002 5:19 pm

I do not know where the cowling is located at on the BAC Spey engine nacelle. If you would like i can make an MP3 of the interior start up sounds of both engines one on the 200 then the 500 to let you hear what im talking about.....there is distinct diff.....the starter motors may be the same but sound that it makes on the 400 and 500 is very loud....like an air raide siren....its kinda freaky... but very neat!!!!!

Access-Air

I hate to ask this again but you wouldnt happen to know why the Un-hushed RR Dart screams. I asked this once but it was never really answered. What makes it scream...???

 Smile
Remember, Wherever you go, there you are!!!!
 
geotrash
Posts: 293
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RE: BAC-111 Startup Sounds!

Tue Apr 02, 2002 7:37 pm

Fascinating discussion. Access-Air, it would bring back great memories to hear the startup sequence from these old machines once again. If it isn't too much trouble, it would be wonderful of you to make the recordings. If you wish, you can e-mail them to me [email protected] and I will place them on my web server, and post a link back here for all to enjoy.

Thanks!
-Geo
 
Smart67
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RE: BAC-111 Startup Sounds!

Fri Dec 31, 2010 5:23 pm

I know this is a very old thread, but it caught my attention. The sound you speak of is a hydraulic starter. USAir, for example, had two types of BAC-111 200 series airplanes. The Mohawk Airlines BAC-111 aircraft had hydraulic starters on their Spey engines. The Braniff types were air starters. I say this based on what I've heard flying on each type. The hydraulic starter BAC-111 makes a loud howling sound while on the starters - like that air raid siren. On board, there's the THUMP of hydraulic pressure and the sound of a shuttle valve to direct pressure - then, the engine begins to turn. You should hear these guys when there's air in the hydraulic system. They hit the starter and it sounds like it's coming apart.

Visit YouTube and key in BAC-111 - there's a BAC-111 400 with hydraulic starters. You get to hear them.

My email is [email protected] if you'd like to chat more.

Jim - Palmdale, CA
 
access-air
Topic Author
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RE: BAC-111 Startup Sounds!

Fri Dec 31, 2010 7:12 pm

The 200 series that I flew on was a former original Braniff machine, flew on it as Braniff number 2 in 1989......It was tail number N1543...
Im sure that all the Speys on all the BACs sound the same with the air raid siren sounds....Its just that the 200 series plane that I flew on on that day didnt make them...Who knows....

Access-Air
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sdf880
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RE: BAC-111 Startup Sounds!

Sat Jan 01, 2011 6:44 pm

If I recall right N1543 was nicknamed "Christine" by the crews. Like the car in the movie sounds like this a/c had a mind of it's own. I flew on it several times and it seemed to be like any other 1-11. I too remember the 1-11 start up sounds, wish I could hear them live again!

SDF880
 
411A
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 1:44 am

Quoting Access-Air (Reply 4):
I hate to ask this again but you wouldnt happen to know why the Un-hushed RR Dart screams. I asked this once but it was never really answered. What makes it scream...???

Two different noise sources.
1. Engine inlet compressor whine.
2. Pressurization Roots blower noise, as the Roots blower is driven by the accessory gearbox.

Both sounds disapate as the engine RPM is accelerated beyond 11,000.
 
jetstar
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 1:56 am

Back in my days working as an A&P mechanic at HPN, the company I worked for was on call whenever Mohawk Airlines had a maintenance problem.

For a time on Mohawk’s BAC-111’s, they were having starter problems in that the starter would not power up, but there was an over ride button on the starter solenoid that had to be held down manually when the engine was started until the starter disengaged.

I, and another mechanic was checked out by Mohawk maintenance personnel in the procedure to start the engine. Basically I opened the cowling, held down the button, the starter would engage, the engine would start and after start close the cowling.

On one of their airplanes, one engine had to be manually started every time, they did not want to take the airplane out of service to replace the bad part, so they arranged to have maintenance personnel at every airport to start the engine.

Mohawk’s station manager at HPN even put through a request to the company to have me fly with the airplane all day to start the engine, but the company turned him down. Would have been a nice day, work for 10 minutes and sit in an airplane for the rest of the day.

I do clearly remember the loud noise these starters made, you could hear them all the way across the airport as the starter noise increased and then quickly died down when the starter disengaged.

JetStar
 
iRISH251
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 1:56 pm

Having "grown up" watching Aer Lingus 1-11-200s at DUB at fairly close quarters, I clearly recall these having the same distinctive start-up noises as the other 1-11 variants that were also common here at the time.
 
oldtimer
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 2:46 pm

Quoting Smart67 (Reply 6):
The Mohawk Airlines BAC-111 aircraft had hydraulic starters on their Spey engines

I worked on and with BAC1-11's from 1965thru to 1990. The one's I was finally "involved" with were at USAir at Pittsburg which included the exBrannif and Mohawk fleets. I have never heard of a hydraulic starter for the 1-11, and I did start my career in civil aviation at the maufacturer at Hurn Airport. The first 1-11 I ever flew was a Mohawk on a test flight and that had a normal CSDS start system.

Would be interested to hear more, as an engineer for over 40 years , I have never heard of a hydraulic engine starter.

JETSTAR, what solenoid did you press on a 1-11, I know you could manually start a 707 or any other air driven starters but cannot see for the life of me where you could do this on a 1-11

oldtimer
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jetstar
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 6:49 pm

[quote=oldtimer,reply=12]JETSTAR, what solenoid did you press on a 1-11, I know you could manually start a 707 or any other air driven starters but cannot see for the life of me where you could do this on a 1-11

oldtimer

This is going back 40 years ago, but if I remember correctly, it was either a solenoid or a valve that allowed the high pressure air to go into the starter, and it was an air starter, not hydraulic. The valve was on the bottom of the engine on the upper part of the CSD, and I had to push down on it. but I did not need a ladder or step stool, I was able to reach it standing from on the ground.

I had to push and hold in a button, one of the pilots would lean out the cockpit window and when I had the button pushed in, I would signal them and they then would start the engine and I had to hold the button in until the starter dropped out. On one airplane, they even had the spare part with them hoping to get it changed on the road, that airplane was the one that the station manager wanted me to fly with them all day to start the engine.

JetStar
 
2H4
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 7:07 pm

JetStar, you're one of my favorite storytellers around. Your posts make me want to drop everything, go get my A&P, and wrench for a living.
Intentionally Left Blank
 
oldtimer
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RE: BAC-111 Startup Sounds!

Sun Jan 02, 2011 9:29 pm

Quoting JETSTAR (Reply 13):
This is going back 40 years ago, but if I remember correctly, it was either a solenoid or a valve that allowed the high pressure air to go into the starter, and it was an air starter, not hydraulic. The valve was on the bottom of the engine on the upper part of the CSD, and I had to push down on it. but I did not need a ladder or step stool, I was able to reach it standing from on the ground.

I had to push and hold in a button, one of the pilots would lean out the cockpit window and when I had the button pushed in, I would signal them and they then would start the engine and I had to hold the button in until the starter dropped out. On one airplane, they even had the spare part with them hoping to get it changed on the road, that airplane was the one that the station manager wanted me to fly with them all day to start the engine.

I'll pm you JETSTAR

oldtimer
Oldtimer, I should have known better!
 
Clydenairways
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RE: BAC-111 Startup Sounds!

Wed Jan 05, 2011 5:24 pm

There was a difference in start up sound between the -200 and -400/500 for sure.
In Dublin we used to have EI with the -200's and BA with the -400's and 500's.

While both aircraft had a similar initial starter sound as described in the above posts (although 400/500 seemed a little bit deeper), the main difference seemed to be towards the end of the start.
During this phase the -200 had a very distinct "squealing down" sound which is the best way i can discribe it. It was a real distinctive charecteristic of the model.

If the -200's in the US did not have this distinct sound then maybe EI had a different starter on their 1-11's.
 
oldtimer
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RE: BAC-111 Startup Sounds!

Wed Jan 05, 2011 7:02 pm

Quoting clydenairways (Reply 16):
If the -200's in the US did not have this distinct sound then maybe EI had a different starter on their 1-11's

All BAC 1-11's had the same starter and it is the CSD

oldtimer
Oldtimer, I should have known better!
 
cmb56
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RE: BAC-111 Startup Sounds!

Fri Jan 07, 2011 11:55 pm

I worked on BAC1-11s at Florida Express back in the 80's out of Cincinnati OH.

There were two different air starters used on those aircraft. One was made by a British Company, Plessy I think and the other was made by Garrett. The British version was like a roots supercharger run backward as a motor. The Garrett was a true air turbine. They had sounds so different you could tell them apart half a mile away. By the way I remember an aircraft name Christine too. It had a habit of landing with the anti-skid locked on one wheel.
 
cmb56
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RE: BAC-111 Startup Sounds!

Sat Jan 08, 2011 2:28 pm

I searched the photo data base and found 1 picture of good old "Christine" N1543 showed up on page 3 of 3 for BAC1-11s and Florida Express. When I last say her in 1988 she was still orange and white.
The manual starts I remember doing required the use of a plastic hammer to give the start solenoid a tap while the pilot pushed the start button in the cockpit. A sticking start solenoid was a fairly common problem.
I also remember on cold days having to start the engines just before the crew showed up or else we would take a delay since one or the other engine would not start using "standard crew procedures" . We mechanics had our own process for getting balky engines to start.

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