The original Trident 1C had leading edge droop. It wasn't a slat because there was no slot, otherwise worked the same.

Sorry, SLF ignorance. Hadnt appreciated the distinction between droops and slats !!

Original question remains though. Does anyone know why Trident had the extra lift devices over the 1-11?

Pedant mode on.....

It's flaps, slats but droop, not droops.


....pedant mode off.

Hobo

It's flaps, slats but droop, not droops.

hahaha. Ok if we are being pedantic, and to satisfy my curiosity, if there is one 'droop' on each wing, should the plural not be employed? Or do you consider the aircraft to have just one wing rather than a port and starboard? Or is there something else? :confused:

Why the leading edge devices?
 

A definitive answer requires input from someone in the project office at the time, but a few pointers are clear: the Trident was designed to be as fast as was feasible in the early 60s. This meant a good high speed wing section, and with the wing sections available at the time, a relatively high sweep back (I don't recall the exact number but a comparison with the 1-11 shows that the Trident had a lot more). Such sections are also not noted for good high lift at low speeds so a degree of 'variable geometry', in this case camber, was needed to keep take-off and landing speeds, as well of course field lengths, within bounds. As it was the aircraft had the reputation of a ground gripper (though that has a lot to do with the installed thrust). Its contemporary the 727 sprouted even more impressive high lift devices as Boeing wanted even better field performance though I think they weren't aiming at quite such high cruise Mach (T1 MMO - M0.88, 727 0.84 at a guess). Nowadays advanced sections allow the same Mach cruise with about 15 degrees less sweep and better low speed performance, but once the moving leading edge genie was out of the bottle it was employed to optimise the designs and all the current crop of airliners use them.

Gonebutnotforgotten

Thanks for that explanation, makes perfect sense to this humble SLF. However as you say it would be interesting to hear from anyone who might have been involved in the design or planning process.

Wookey AFAIAA it has never been referred to in the plural apart from the non pilot origin PI stuff and here. Flaps and slats are referred to in the plural because there are usually more than one section of each on each wing, but there was only one section of droop. On most types, the call is Flap 1,5,30 etc. I.e. in the singular.

Based on my experience of over 6000 sectors and around 10,000 hours flying Tridents of all types plus over 100 simulator sessions and being involved on the technical side as well; I'm here to tell you, it's droop not droops.

Hobo

Fair enough. Having re-read my earlier reply I can see that it might be misconstrued. However it was a genuine question as to why droop would be singular but flaps and slats were referred to in the plural which you have now explained perfectly. Apologies if you thought my response impertinent.

Merry christmas to you and all contributors to this thread

"Original Trident"
 

Not sure whether I dreamt it, but I seem to recall that the original DH Trident design was of Trident Three size with Medway (larger) engines and slats (not droop) leading edge devices - then BEA got involved by demanding a smaller and "simpler" aircraft - hence the T1 with Speys and droop L/E?

Gone but not forgotten.



MMO on the 727 was .92 Mach, actually making it a little faster.


it was very comfortable at that speed, although a little noisy, like the Trident it was a superb high speed aircraft but with its elaborate wing still able to have good field performance.

The T1C wing was certainly optimised for high speed cruise, as it had 38 degrees of sweepback, and high lift devices were required to get acceptable lift off the wing for takeoff and landing. It had a Vmo of 380 kts and, if I remember correctly, a Mmo of 0.93M and cruise of .885. this was later reduced to 365kts and 0.85M cruise to come into line with the T2, which at 35 degrees sweepback was a little slower. The B727 had a higher Vmo but surely not a higher Mmo, as we used to leave them standing in the cruise.

The T1 had excellent high speed handling. I remember seeing over 0.95M during our high fly exercise (cb pulled) and there was no buffet or airflow separation, even turning at 30 degreees of bank, just a slight rumble from the ailerons. During the emergency descent manouevre, the rate of descent could only be determined by use of a stopwatch and the altimeter between FL300 and FL200, as the VSI was jammed onto the bottom stop. It was in excess of 18,000 fpm, a capability the ATC soon learned to make good use of.

In the late 60's as the autoland system was developed and proved, we were initially only allowed to carry out 'autoflare' landings, with roll control provided by the pilot. After a certain number of these had been completed we moved onto full autoland, right down to Cat 3c capability. This was found to be impracticable, as in complete zero vis it was impossible to taxy or be found by the emergency services, so Cat 3b with 75 metres vis was established as the working minimum.

A further feature of the T2 was water injection for the Spey 512 engines. This was used to uprate the performance out of short and/ or hot airfields, such as the old Malta Luqa or Nicosia airfields. This provided about three minutes of sporty performance, but the water usually ran out at about 20 kts below the slat retract speed, leaving the aircraft ' hanging' in ISA +15 air and very reluctant to accelerate. A very long practically level segment was required to get up to clean climb speed. The system was not used extensively and was soon withdrawn, as a water injection pump failure left a tank of water on board which could freeze at altitude.



While I can still remember:
T1 full tanks: 13680 kgs
T2 full tanks including fin fuel 23040kgs
T2 full tanks without fin fuel 21809 kgs.

VMO / MMO on the 727 was adjustable, depending on zero fuel weight.


A switch labelled A / B mode changed this limit.


In A mode VMO, was 380 knots MMO .92


In B mode VMO was 350 / .85.


the Trident was certainly a fast ship and it sounds like you regularly flew them at the limit, in the 727 we rarely did as the fuel flow above .86 was horrendous.

YouTube - Blackbox - 05 - Blaming the Pilot - Part 2 of 5

Captain Jonathan Scott of BA refers to them as "droops" in this Black Box reconstruction of PI (circa 1997). That may be just in this case though.

Hi

probably a daft question as I'm SLF but here goes

in terms of % or Newtons or any other unit, how much extra thrust/power was gained by the use of water injection in the Spey 512?
By how much did it alter the take off and climb performance of the Gripper

Regards

Neil B

Trident
 

Hello everybody.

I worked at one time 1963 thru 71 for BEA in Paris Le Bourget Airport. I was in charge of the Load Control section and also acting Duty Officer and therefore pretty often on the tarmac. Owing to the BEA/BOAC merger I quit BEA and joined a US carrier as Station Manager Paris.

Reading this thread brought back many many happy memories. Dealing with Vicounts, Vanguards 951 & 953, Merchantman, Argosy, Comets, all the Tridents.
I recall, if I am not mistaken, that when the T3 came into service the Pilots called it the "5 APU Aircraft". Does anyone remember that ? or is my memory playing tricks ?

I'm sure I know quite a few of you wether venerable LHS or young F/O's at the time. Of course time has gone by for all of us and I often wonder if any of the LHS who were involved in WW2 are still with us.

Well many thanks indeed for having written so many nice things on that wonderful baby that was the Trident.

Trident was certainly fast, but not for long!

IIRC, the Trident 1E was delivered to Iraqi Airways (remember them?) by Hawker Siddeley (remember them?) with a guaranteed 85 pax from Baghdad to Cairo on an ISA+(XX) day. The reality was 16 pax in representative summer temperatures!

The Trident only oprated for ten years before the 727 replaced them in IA service!

16 only?

Jeez Louise..that wasn't good.

T2 Performance
 

I believe the STD from TLV to LHR was 0725.

In the summer, any delay would involve the possibility of offloading pax, due to the rapidly increasing OAT (That was after the water injection system was disabled).

I got to know the stop-end of 30 from just a few feet into the air.

I often wondered what would have happened with an engine failure at V1 + 1kt. Thankfully, no-one ever found out.

In the case of the Trident, "Spey" turned out to be an unfortunately appropriate homonym.

"Droops" etc
 

“Droops” would have caused any Gripper pilot to give one a very sideways look. It was never called that.
M.92 was regularly used in base training but I never heard of it being used in the cruise. I can only imagine what the fuel flow would have been.
I have mentioned in another link, during an emergency descent (real) the stopwatch proved a rate of descent of 22,000fpm. (In BEA it was drummed into us to use the stopwatch for everything. It seems to have rather gone out of fashion now, and I suspect this is partly (?) due to the idiot proof mechanism of the Boeing offering.)
Water Injection was certainly fitted to the T2. I cannot recall it ever actually working, but have many memories of it failing during the Take Off run and having to return to p..s the rest of it out all over the tarmac. It was a rather expensive embarrassment.
Early departures from the Eastern Med were required for performance reasons, but I remember one close shave due temperature. The flight (T3 IIRC) left Luqa in the cool of the dawn but at 1500ft nearly fell into the sea. It was fortunate that 24 was in use and there was sea to descend to! There was a very acute inversion at 1500ft in the order of 20C and the results were dramatic to say the least.
For FlamantRose, I flew into Le Bourget in both the Vanguard and the Trident and remember the lovely smell of many sticks of real French bread in the flight deck on the way home. I don’t remember 5 APU’s but the Boost Engine was often referred to as just another APU.
Prober

I never saw it myself from outside, but when starting the boost, at night, just before entering the runway, I had a couple of comments that flame had appeared on light up.

From a Clipper 747: "...er tower...there's a sheet of flame just come out of the APU on this seven twenty seven ahead of us here holding 28R.....".

Tower: " Speedbird XXX confirm you've just started your boost?"

I suppose using the boost was a relatively unusual occurence anyway, I suspect about 5% of take offs max??

I also recall a couple of occasions ex Malta and Naples in T3's (and NIC in a T2) climbing into a severe inversion and it was only the curvature of the earth that gave us a climb. IIRC the Malta incident that Prober refers to prompted a serious look into the phenomenon, and there was a subsequent temp correction applied worldwide to all types for T/O performance in such circumstances.

Fortunately the T3 couldn't make NIC or TLV in one go.