Blackbird From , joined Dec 1969, posts, RR: Posted (5 years 9 months 3 weeks 6 days 1 hour ago) and read 2354 times:
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?
Strathpeffer From United Kingdom, joined Jan 2007, 79 posts, RR: 0 Reply 1, posted (5 years 9 months 3 weeks 5 days 17 hours ago) and read 2303 times:
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.
Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66 Reply 2, posted (5 years 9 months 3 weeks 5 days 17 hours ago) and read 2303 times:
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." - from Citadel by John Ringo
LAPA_SAAB340 From Spain, joined Aug 2001, 389 posts, RR: 5 Reply 4, posted (5 years 9 months 3 weeks 5 days 12 hours ago) and read 2245 times:
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 From United Kingdom, joined Nov 2001, 1382 posts, RR: 17 Reply 5, posted (5 years 9 months 3 weeks 5 days 12 hours ago) and read 2241 times:
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.
Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66 Reply 6, posted (5 years 9 months 3 weeks 5 days 10 hours ago) and read 2204 times:
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"
"There are no stupid questions, but there are a lot of inquisitive idiots." - from Citadel by John Ringo
TristarSteve From Sweden, joined Nov 2005, 3692 posts, RR: 34 Reply 8, posted (5 years 9 months 3 weeks 4 days 13 hours ago) and read 2071 times:
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.
GDB From United Kingdom, joined May 2001, 12708 posts, RR: 80 Reply 10, posted (5 years 9 months 3 weeks 4 days 11 hours ago) and read 2050 times:
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 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 11, posted (5 years 9 months 3 weeks 4 days 11 hours ago) and read 2042 times:
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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.
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 71 Reply 12, posted (5 years 9 months 3 weeks 4 days 11 hours ago) and read 2037 times:
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.
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.
2H4 From United States of America, joined Oct 2004, 8950 posts, RR: 62 Reply 14, posted (5 years 9 months 3 weeks 4 days 10 hours ago) and read 2023 times:
AIRLINERS.NET CREW HEAD DATABASE EDITOR
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?
VC10 From United Kingdom, joined Nov 2001, 1382 posts, RR: 17 Reply 15, posted (5 years 9 months 3 weeks 4 days 10 hours ago) and read 2022 times:
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
LAPA_SAAB340 From Spain, joined Aug 2001, 389 posts, RR: 5 Reply 16, posted (5 years 9 months 3 weeks 4 days 10 hours ago) and read 1998 times:
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"!
Starlionblue From Hong Kong, joined Feb 2004, 15870 posts, RR: 66 Reply 17, posted (5 years 9 months 3 weeks 4 days 8 hours ago) and read 1974 times:
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." - from Citadel by John Ringo
Leebird From United States of America, joined Sep 2006, 17 posts, RR: 0 Reply 20, posted (5 years 9 months 3 weeks 3 days 21 hours ago) and read 1893 times:
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.
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