Blackbird
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HS-121 Trident Takeoff Run Questions

Tue Jul 31, 2007 12:20 pm

What was the takeoff speeds and takeoff run for a fully loaded HS-121? Also do you know what speeds and takeoff runs wo uld exist for light to medium weights?

Andrea kent
 
Strathpeffer
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RE: HS-121 Trident Takeoff Run Questions

Tue Jul 31, 2007 8:13 pm

I can't be specific I'm afraid, but you might be amused to know that the Trident was known as the 'gripper' - so determined was it to remain on solid ground.

Pilots joked that the sole reason it took off at all was due to the curvature of the earth.

 

PJ

[Edited 2007-07-31 13:22:09]
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Starlionblue
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RE: HS-121 Trident Takeoff Run Questions

Tue Jul 31, 2007 8:19 pm

Quoting Strathpeffer (Reply 1):
I can't be specific I'm afraid, but you might be amused to know that the Trident was known as the 'gripper' - so determined was it to remain on solid gorund.

Pilots joked that the sole reason it took off at all was due to the curvature of the earth.

That's why they had to put in a fourth engine, surely one of the more desperate engineering fixes in aviation...
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Strathpeffer
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RE: HS-121 Trident Takeoff Run Questions

Tue Jul 31, 2007 8:24 pm

Quoting Starlionblue (Reply 2):
That's why they had to put in a fourth engine, surely one of the more desperate engineering fixes in aviation...

Imagine if VS had been around to operate it:

"4 engines 4 it to fly at all"

PJ
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lapa_saab340
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RE: HS-121 Trident Takeoff Run Questions

Wed Aug 01, 2007 1:04 am

The RB162 booster engine was only fitted to the Trident 3B, and then it was used when conditions required it (i.e. heavy loads, high density altitude; perhaps a former Trident driver can comment on how frequently this happened). It might have been a somewhat odd arrangement, but I wouldn't call that a desperate engineering fix. Given that there were no higher-power RR Spey variants available, the booster allowed for additional thrust without a major modification of the powerplant installation for the 3B variant.
 
vc10
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RE: HS-121 Trident Takeoff Run Questions

Wed Aug 01, 2007 1:21 am

Quoting Strathpeffer (Reply 1):
Pilots joked that the sole reason it took off at all was due to the curvature of the earth.

I think you will find that the above comment really only applied to the Trident 1 , which had lower thrust engines ,and I also believe that on the Trident 1 they would often have to slightly throttle the centre engine when the aircraft started to rotate so as to prevent it exceeding it's EGT limit as the intake became shielded by the fuselage on rotation. This was over come so I understand on later versions of the Trident.

littlevc10
 
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Starlionblue
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RE: HS-121 Trident Takeoff Run Questions

Wed Aug 01, 2007 3:44 am

Quoting LAPA_SAAB340 (Reply 4):
The RB162 booster engine was only fitted to the Trident 3B, and then it was used when conditions required it (i.e. heavy loads, high density altitude; perhaps a former Trident driver can comment on how frequently this happened). It might have been a somewhat odd arrangement, but I wouldn't call that a desperate engineering fix. Given that there were no higher-power RR Spey variants available, the booster allowed for additional thrust without a major modification of the powerplant installation for the 3B variant.

I know, but it seems like a little bit of a kludge. I think that nowadays growth variants are envisaged from the very beginning, while in those days maybe they were not planned for as much.

Quoting Strathpeffer (Reply 3):

Imagine if VS had been around to operate it:

"4 engines 4 it to fly at all"

 rotfl   rotfl   rotfl   rotfl   rotfl 
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
FredT
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RE: HS-121 Trident Takeoff Run Questions

Wed Aug 01, 2007 6:03 pm

Google is always a good start. Here's a manual of sorts, for flight sim but seems solid enough:

http://www.dmflightsim.co.uk/html/Trident/Manual.htm

Includes speed book etc. Doesn't specify version of the aircraft though, as far as I could see at first glance.

I'd love to get my hands on a Trident manual myself. For some reason I really like the aircraft.

BTW, know how they got it to take off? Curvature of the earth...  Wink
I thought I was doing good trying to avoid those airport hotels... and look at me now.
 
Tristarsteve
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 12:25 am

Ah the de Havilland Trident. My first aircraft.
The Boost engine was amazing. It was designed as an engine for a vertical lift aircraft. It had a plastic compressor, a total loss oil system and a very short life, and was very light weight. But it was only used for 10 mins every now and then. That was the problem. It was never used so was a bit!! tempremental when it was needed. The pilots started it up during the taxy, bit like an APU. It ran up to idle and made an incredible noise. Then when two (out of three) throttles were set to take off it accelerated to take off. It had two speeds, idle and take off. When the throttles were pulled back to climb, it shut down.
The Trident 2 had similar Spey 512 engines to the Trident 3. (The Trident 1C had Spey 505). But the Trident 2 engines had water injection. Yet again the problem was that the water injection system was only used now and then, and thw water pump used to seize through lack of use. So in the end only about 5 Trident 2s had water pumps fitted, and they were dedicated to the long Med routes like Nicosia and Athens.
 
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Starlionblue
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 1:00 am

Quoting TristarSteve (Reply 8):
a total loss oil system

? Could you please expand on this?

Quoting TristarSteve (Reply 8):
It had two speeds, idle and take off.

Just like my daughter then. Big grin
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
GDB
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 2:10 am

Tridents taking off were in some respects, worse for noise than Concorde, mainly because the latter was up and away quickly, whilst the dear old Trident seemed to take forever.....
 
2H4
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 2:21 am

Quoting Starlionblue (Reply 9):
Quoting TristarSteve (Reply 8):
a total loss oil system

? Could you please expand on this?

If I'm not mistaken, it's the same type of system used in the Rolls-Royce Viper turbojet.

The best description I've seen comes from Airplanedriver.net, where the Hawker 1A is described (from a systems standpoint) as the "Luxury Jet of the Flintstones".


The Rolls Royce Viper engine powers all of the "Straight Pipe" Hawker Jets. It was originally designed to power drones, and be destroyed by some new weapon system in short order.

It did, however, turn out to be a very reliable engine, and was installed on the Hawker Jet. One odd thing is that there was no provision to recover the oil that is used to lubricate the aft engine bearing. This oil was discharged into the jet exhaust, and never seen or heard from again. To this day, this is still true. You must service the engine oil almost each flight. Other than this, it was really a good engine in it's day.



2H4

Intentionally Left Blank
 
SlamClick
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 2:39 am

Quoting Strathpeffer (Reply 1):
Pilots joked that the sole reason it took off at all was due to the curvature of the earth.

Good one! It used to be said that if you could build a runway all the way around the world at the equator Republic Aircraft would design a fighter that needed it.

Quoting TristarSteve (Reply 8):
total loss oil system and a very short life

If I'm not mistaken the engine in the A-4 Skyhawk also had this on at least one bearing package. Interesting that you can figure out a path for the oil to get in there but not a way to scavenge it back into the system.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
Tristarsteve
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 2:45 am

Quoting Starlionblue (Reply 9):
Quoting TristarSteve (Reply 8):
a total loss oil system

? Could you please expand on this?

Because of the short run time, it had no scavenge system at all. The oil was pumped into the bearings, and left via the jet pipe.
 
2H4
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 3:05 am

Quoting TristarSteve (Reply 8):
The Boost engine was amazing. It was designed as an engine for a vertical lift aircraft. It had a plastic compressor, a total loss oil system and a very short life

What was the TBO on that thing? How many cycles (I assume it wasn't based on hours) could you generally get out of it before overhaul? How many before replacement?


2H4

Intentionally Left Blank
 
vc10
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 3:12 am

Quoting 2H4 (Reply 11):
It did, however, turn out to be a very reliable engine, and was installed on the Hawker Jet. One odd thing is that there was no provision to recover the oil that is used to lubricate the aft engine bearing. This oil was discharged into the jet exhaust, and never seen or heard from again. To this day, this is still true. You must service the engine oil almost each flight. Other than this, it was really a good engine in it's day.

This sounds just like a Wright 3350 which needed oil by the gallon after every trip, and sometimes even during the trip.

I remember somebody asking how often the oil was changed on a Connie and my answer was about every 2 or 3 trips whether you liked it or not. I also used to call it the Connie's anti- corrosion treatment  Wink

littlevc10
 
lapa_saab340
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 3:50 am

TristarSteve, very interesting, thanks for sharing! I had always wondered how they controlled the booster engine. Must have made quite a bit of racket on takeoff with all 4 engines running.

Quoting Starlionblue (Reply 6):
I know, but it seems like a little bit of a kludge. I think that nowadays growth variants are envisaged from the very beginning, while in those days maybe they were not planned for as much.

I know what you mean. The potential growth of the Trident was affected by being tailored to BEA's specifications and the RR Medway engines never being developed. I wonder what plans Hawkery Siddeley might have had for it...

Quoting SlamClick (Reply 12):
Good one! It used to be said that if you could build a runway all the way around the world at the equator Republic Aircraft would design a fighter that needed it.

Ahhh good old Republic. Also known as "The Foundry"!
 
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Starlionblue
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 5:00 am

Quoting 2H4 (Reply 11):
It did, however, turn out to be a very reliable engine, and was installed on the Hawker Jet. One odd thing is that there was no provision to recover the oil that is used to lubricate the aft engine bearing. This oil was discharged into the jet exhaust, and never seen or heard from again. To this day, this is still true. You must service the engine oil almost each flight. Other than this, it was really a good engine in it's day.



Quoting Tristarsteve (Reply 13):
Because of the short run time, it had no scavenge system at all. The oil was pumped into the bearings, and left via the jet pipe.

Thank you gentlemen.

Quoting SlamClick (Reply 12):
If I'm not mistaken the engine in the A-4 Skyhawk also had this on at least one bearing package. Interesting that you can figure out a path for the oil to get in there but not a way to scavenge it back into the system.

Well, they might have been able to figure it out. But then they might have figured out that it would have cost and weighed more than it was worth.

Nowadays, the environmental regs would probably put the brakes on such an implementation in short order.

Quoting LAPA_SAAB340 (Reply 16):
I know what you mean. The potential growth of the Trident was affected by being tailored to BEA's specifications and the RR Medway engines never being developed. I wonder what plans Hawkery Siddeley might have had for it...

As I recall, the Trident was very much handicapped by changing and often irrational specifications. This is in many ways true for the entire postwar UK aviation industry. Just look at the TSR-2: http://www.thunder-and-lightnings.co.uk/tsr2/history.html. BTW that is a great website.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
dc863
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 6:03 am

Here's the t.o data for G-ARPI a Trident I which crashed shortly after takeoff from runway 27R in June 1972.

Flaps 20 degrees.
V1 134 kts
Rotate 139kts
V2 152kts
takeoff run lasted 44 sec.

takeoff weight 50,000kg.
 
Blackbird
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 1:28 pm

Okay, how much distance would a 44 second takeoff run with a V1 of 134, VR of 139 and V2 of 152 kts?

Andrea Kent
 
leebird
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RE: HS-121 Trident Takeoff Run Questions

Thu Aug 02, 2007 4:45 pm

If 152 kts = 256.54 feet per second,

simple kinematics gives us a length of 5643.88 feet.

I'm thinking that drag, non-constant acceleration, etc can be ignored in this case because the numbers are observed, thus these factors are already included into the calculation. But since its nearly 4 am here, I could be wrong.
 
Strathpeffer
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RE: HS-121 Trident Takeoff Run Questions

Fri Aug 03, 2007 6:41 am

Found this in "Jetliners in Service Since 1952" by John Stroud. Hope it is useful...

Trident 1 - London to Munich (TO Weight 50724kg)...

V1 143kts
VR 148kts
V2 158kts

...and on the return (TO Weight 49538)...

V1 141
VR 146
V2 156

...and in a 3B from London to Glasgow (TOW 53000, 16deg Flaps).

V1 125
VR 130
V2 139

PJ

[Edited 2007-08-02 23:42:48]
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