Detailed Discussion Desired: Flying in the Past
Hi oldchina,
Frustrating that I don't have any sample figures, but I think on the 1-11/500 the most limiting factor for the RTOW (other than the structural MTOW of 45200kg/99650lb) out of many of the sea-level Spanish airfields in hot summer wx may have been WAT, rather than runway length. You are quoting figures at ISA on an 8000-foot runway, where runway length is evidently the limiting factor.** I'm talking about something in the region of ISA+20 (35C), where the most limiting factor could be either WAT or the runway criteria (TORA/EDA/TODA) or, of course, net take-off flight-path (obstacles, as at Malaga).
Allan may have identified the problem-area. I think the Spey was flat-rated, as he says, and perhaps to ISA+20. Maybe the flat-rating stretched to a higher figure with water-injection? I really don't remember.
Frankly, the 500 series was under-powered for summer weather on the Costas! We needed the B737-200. (Many years later, as you know, we got the A320, but that's another story.)
** Must admit I'm surprised your figures show the 500 srs incapable of achieving MTOW off an 8000-foot runway at sea-level (still-air?) without water injection. Worse than I thought.
Frustrating that I don't have any sample figures, but I think on the 1-11/500 the most limiting factor for the RTOW (other than the structural MTOW of 45200kg/99650lb) out of many of the sea-level Spanish airfields in hot summer wx may have been WAT, rather than runway length. You are quoting figures at ISA on an 8000-foot runway, where runway length is evidently the limiting factor.** I'm talking about something in the region of ISA+20 (35C), where the most limiting factor could be either WAT or the runway criteria (TORA/EDA/TODA) or, of course, net take-off flight-path (obstacles, as at Malaga).
Allan may have identified the problem-area. I think the Spey was flat-rated, as he says, and perhaps to ISA+20. Maybe the flat-rating stretched to a higher figure with water-injection? I really don't remember.
Frankly, the 500 series was under-powered for summer weather on the Costas! We needed the B737-200. (Many years later, as you know, we got the A320, but that's another story.)
** Must admit I'm surprised your figures show the 500 srs incapable of achieving MTOW off an 8000-foot runway at sea-level (still-air?) without water injection. Worse than I thought.
Last edited by Chris Scott; 16th Feb 2017 at 21:37. Reason: Flat-rating theory adjusted.
Join Date: Dec 2001
Location: London
Posts: 260
Likes: 0
Received 0 Likes
on
0 Posts
I flew the 111-510 mainly on the Berlin operation, but we didn't have water injection - the only time we could have done with it was out of STR Rwy 08 going back to LHR in the summer when we were WAT limited on occasions
Join Date: Nov 2016
Location: Carlisle
Posts: 28
Likes: 0
Received 0 Likes
on
0 Posts
The "flapping" noise on Dart aircraft came from the prop leading edge erosion strips, held on with evostick type adhesive, the strips would erode or tear, become unstuck.
Impossible to rectify on the line due to the long drying time of the adhesive.
I've seen the results of forgetting to select WM on take of, torque goes off the clock and ITT follows it.
Impossible to rectify on the line due to the long drying time of the adhesive.
I've seen the results of forgetting to select WM on take of, torque goes off the clock and ITT follows it.
Join Date: Mar 2010
Location: on a blue balloon
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Chris Scott:
"Frankly, the 500 series was under-powered for summer weather on the Costas!"
It certainly was, but what else could carry 119 pax back from their hols on less total
installed thrust than one CFM56?
Hence the WAT problem and the fact that BAC never considered giving it draggy leading edge slats.
"Frankly, the 500 series was under-powered for summer weather on the Costas!"
It certainly was, but what else could carry 119 pax back from their hols on less total
installed thrust than one CFM56?
Hence the WAT problem and the fact that BAC never considered giving it draggy leading edge slats.
Quote from Arthur Bellcrank:
"The 'flapping' noise on Dart aircraft came from the prop leading edge erosion strips, held on with evostick type adhesive, the strips would erode or tear, become unstuck.
Impossible to rectify on the line due to the long drying time of the adhesive."
That rings a bell, and perhaps the peeling strips flapped even harder with the slightly coarser blade-pitch when water-meth was being used.
Good point, oldchina. BTW, I recall that the total cruise fuel-flow was about 2200kg/hr with 119 pax at M0.70**, whereas the A320 with (say) 168 pax is about 2400kg/hr at M0.78. Not completely sure what you mean by "draggy slats", however?
** [Edit] Or was it M0.73?
"The 'flapping' noise on Dart aircraft came from the prop leading edge erosion strips, held on with evostick type adhesive, the strips would erode or tear, become unstuck.
Impossible to rectify on the line due to the long drying time of the adhesive."
That rings a bell, and perhaps the peeling strips flapped even harder with the slightly coarser blade-pitch when water-meth was being used.
Good point, oldchina. BTW, I recall that the total cruise fuel-flow was about 2200kg/hr with 119 pax at M0.70**, whereas the A320 with (say) 168 pax is about 2400kg/hr at M0.78. Not completely sure what you mean by "draggy slats", however?
** [Edit] Or was it M0.73?
Last edited by Chris Scott; 18th Feb 2017 at 21:28.
The 1-11 518 srs. for Court Line had a fixed droop to the leading edge which was developed to allow max weight ops from Luton. Most others after this had the same. Not sure if earlier A/C were modified though.
There were also plans to re-engine the 1-11 with Tays and JT8s but, with the exception of the Dee Howard aircraft, came to nothing.
More wing improvements were trialed on "YD" as the 670 srs.
There were also plans to re-engine the 1-11 with Tays and JT8s but, with the exception of the Dee Howard aircraft, came to nothing.
More wing improvements were trialed on "YD" as the 670 srs.
Last edited by dixi188; 19th Feb 2017 at 07:02. Reason: more
Join Date: Nov 2007
Location: Northampton
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
Before that BAC wanted to use JT 8s but is was at the time of currency controls and was not allowed, so the 1-11 was never developed any further than the 500. After that BAC did not help any new engine developments in case it took sales away from the 146.
Join Date: Mar 2010
Location: on a blue balloon
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
rogerg
I believe BAC offered American Airlines an engine choice for their 30 aircraft order. They selected the Spey.
Chris:
It's just that slats add lift but also the drag that comes along with it. The latter was unacceptable with so little thrust on board.
I believe BAC offered American Airlines an engine choice for their 30 aircraft order. They selected the Spey.
Chris:
It's just that slats add lift but also the drag that comes along with it. The latter was unacceptable with so little thrust on board.
1-11/500 T/O performance
Quote from dixi188:
"The 1-11 518 srs. for Court Line had a fixed droop to the leading edge which was developed to allow max weight ops from Luton. Most others after this had the same. Not sure if earlier A/C were modified though."
Yes, from my experience - limited to BCAL - we eventually obtained two Dash-528FL a/c from Hapag Lloyd to supplement our 500 fleet in 1981/2. They had the new leading-edges you describe, and a choice of three flap-settings for T/O instead of the usual two (8 deg and 18 deg). I think the lowest setting may have been 6 degrees, which would presumably improve the WAT situation (for the second segment climb), provided the runway was long enough to take advantage of it. I don't remember any penalty for cruise performance with the new leading edge.
(Re WAT limitations, the technique in common use today of trading any excess runway to achieve a higher VR and V2, and therefore an improved second-segment climb angle, was never adopted on 1-11 operations - AFAIK. Don't know why we did not try to introduce it in BCAL, because we had already been using it to improve the payload capability of our B707-320Cs out of hot-high-long Nairobi since 1975/6.)
Quote from oldchina:
"It's just that slats add lift but also the drag that comes along with it. The latter was unacceptable with so little thrust on board."
Am no aerodynamicist, and I hesitate to stumble into a debate on what no doubt involves complex compromises for aircraft designers. I appreciate that thrust has to exceed drag on take-off, and it was in rather short supply! But my simplistic understanding is that slats enable an a/c to fly at a lower speed by enabling a higher AoA while maintaining a safe margin from the stall. We are not asking for more lift; merely the same lift at a lower IAS (okay, EAS).
I guess that the higher AoA may involve a slightly inferior L/D ratio (= more drag). The alternative is to use some or more flap, which probably causes an even bigger deterioration in the L/D ratio?
The best WAT performance for take-off on an A310 involves a flapless T/O with slats at the T/O setting. Taking your argument to its logical conclusion, one might expect it to use T/O flap with the slats retracted?
"The 1-11 518 srs. for Court Line had a fixed droop to the leading edge which was developed to allow max weight ops from Luton. Most others after this had the same. Not sure if earlier A/C were modified though."
Yes, from my experience - limited to BCAL - we eventually obtained two Dash-528FL a/c from Hapag Lloyd to supplement our 500 fleet in 1981/2. They had the new leading-edges you describe, and a choice of three flap-settings for T/O instead of the usual two (8 deg and 18 deg). I think the lowest setting may have been 6 degrees, which would presumably improve the WAT situation (for the second segment climb), provided the runway was long enough to take advantage of it. I don't remember any penalty for cruise performance with the new leading edge.
(Re WAT limitations, the technique in common use today of trading any excess runway to achieve a higher VR and V2, and therefore an improved second-segment climb angle, was never adopted on 1-11 operations - AFAIK. Don't know why we did not try to introduce it in BCAL, because we had already been using it to improve the payload capability of our B707-320Cs out of hot-high-long Nairobi since 1975/6.)
Quote from oldchina:
"It's just that slats add lift but also the drag that comes along with it. The latter was unacceptable with so little thrust on board."
Am no aerodynamicist, and I hesitate to stumble into a debate on what no doubt involves complex compromises for aircraft designers. I appreciate that thrust has to exceed drag on take-off, and it was in rather short supply! But my simplistic understanding is that slats enable an a/c to fly at a lower speed by enabling a higher AoA while maintaining a safe margin from the stall. We are not asking for more lift; merely the same lift at a lower IAS (okay, EAS).
I guess that the higher AoA may involve a slightly inferior L/D ratio (= more drag). The alternative is to use some or more flap, which probably causes an even bigger deterioration in the L/D ratio?
The best WAT performance for take-off on an A310 involves a flapless T/O with slats at the T/O setting. Taking your argument to its logical conclusion, one might expect it to use T/O flap with the slats retracted?
Join Date: Aug 2004
Location: UK
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
1-11 perf
Really straining the memory for this but if I recall correctly on a standardish day, still air RW26 at Luton gave an RTOW of 43610kgs (13 flap dry). Using demin water allowed a takeoff at max structural weight of 45200kgs (also 13 flap), so a benefit of 1590 minus 320 kg for the water =1270 kgs of extra fuel or payload.
We did have an "Optimised V2" procedure ("Improved Climb" to Boeing pilots) which IIRC gave an RTOW of about 44500kgs, but there were restrictions on its use, although I don't remember what these were. Anybody?
I always loved the noise!
We did have an "Optimised V2" procedure ("Improved Climb" to Boeing pilots) which IIRC gave an RTOW of about 44500kgs, but there were restrictions on its use, although I don't remember what these were. Anybody?
I always loved the noise!
Quote from Raymond Dome:
"We did have an "Optimised V2" procedure ("Improved Climb" to Boeing pilots) which IIRC gave an RTOW of about 44500kgs, but there were restrictions on its use, although I don't remember what these were. Anybody?"
Never did it on the 1-11 but bans would have included wet or contaminated runways, perhaps? And maybe reduced thrust (assumed temperature method on the 1-11), although the latter's use with optimised V2 is everyday practice on big jets these days to minimise the required thrust.
But was the Luton runway long enough to increase the take-off run for a higher V2, or was runway length more limiting than WAT?
"We did have an "Optimised V2" procedure ("Improved Climb" to Boeing pilots) which IIRC gave an RTOW of about 44500kgs, but there were restrictions on its use, although I don't remember what these were. Anybody?"
Never did it on the 1-11 but bans would have included wet or contaminated runways, perhaps? And maybe reduced thrust (assumed temperature method on the 1-11), although the latter's use with optimised V2 is everyday practice on big jets these days to minimise the required thrust.
But was the Luton runway long enough to increase the take-off run for a higher V2, or was runway length more limiting than WAT?
I always loved the noise!
Hi pulse1,
The Spey certainly has a shrill roar.** If you thought one or two at full chat were noisy on crew training, however, imagine 2, 3 or 4 Conways - as on the VC10. Not to mention, of course, several Olympus 593s on reheat...
** Could you actually detect any difference with that ugly hush-kit?
The Spey certainly has a shrill roar.** If you thought one or two at full chat were noisy on crew training, however, imagine 2, 3 or 4 Conways - as on the VC10. Not to mention, of course, several Olympus 593s on reheat...
** Could you actually detect any difference with that ugly hush-kit?
We were always puzzled that the Trident was no noisier with three Speys than the 1-11 was with two, until we had closer contact with the Weybridge opposition post-nationalisation. They told us that the 1-11's air-driven CSD was responsible - and I presume that the "hush-kit" did not include that in its scope.
Join Date: Mar 2010
Location: on a blue balloon
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Allan
The metal rod carried on some 1-11 flight decks was not there to fight off hijackers, but to whack the bloody CSDS when it got stuck.
The metal rod carried on some 1-11 flight decks was not there to fight off hijackers, but to whack the bloody CSDS when it got stuck.
Last edited by oldchina; 21st Feb 2017 at 10:55.
Not to mention, of course, several Olympus 593s on reheat...
Quote from Allan Lupton:
"We were always puzzled that the Trident was no noisier with three Speys than the 1-11 was with two, until we had closer contact with the Weybridge opposition post-nationalisation. They told us that the 1-11's air-driven CSD was responsible - and I presume that the "hush-kit" did not include that in its scope."
The 1-11's CSDSs definitely produced a horrendous noise on engine start-up, but would they have made any difference after that?
(For those not familiar, a CSD provides a constant-speed drive for the AC generator, which enables the frequency of the AC to be maintained at the standard 400 Hz (if you're lucky!). It's driven mechanically from the engine's accessory gearbox. However, on the 1-11 the two units also incorporated a turbine which enabled them to be turned by the air used for engine start. Most other a/c had dedicated air-starter units on each engine, but the 1-11's CSDS was used to turn the engine via its accessory gearbox. So it combined the two roles. The drive shaft was a bit fragile, having a tendency to shear - particularly during a cold start, and particularly if the pilot was "milking" the HP fuel-cock to avoid exceeding the maximum EGT while the engine struggled to accelerate to idle r.p.m.. When that happened, you had also lost the generator on that engine. As oldchina says, it could also get stuck.)
"We were always puzzled that the Trident was no noisier with three Speys than the 1-11 was with two, until we had closer contact with the Weybridge opposition post-nationalisation. They told us that the 1-11's air-driven CSD was responsible - and I presume that the "hush-kit" did not include that in its scope."
The 1-11's CSDSs definitely produced a horrendous noise on engine start-up, but would they have made any difference after that?
(For those not familiar, a CSD provides a constant-speed drive for the AC generator, which enables the frequency of the AC to be maintained at the standard 400 Hz (if you're lucky!). It's driven mechanically from the engine's accessory gearbox. However, on the 1-11 the two units also incorporated a turbine which enabled them to be turned by the air used for engine start. Most other a/c had dedicated air-starter units on each engine, but the 1-11's CSDS was used to turn the engine via its accessory gearbox. So it combined the two roles. The drive shaft was a bit fragile, having a tendency to shear - particularly during a cold start, and particularly if the pilot was "milking" the HP fuel-cock to avoid exceeding the maximum EGT while the engine struggled to accelerate to idle r.p.m.. When that happened, you had also lost the generator on that engine. As oldchina says, it could also get stuck.)
Last edited by Chris Scott; 21st Feb 2017 at 10:19.
