Trident autothrust system and autoland

[petermcleland]

One other problem with Malta was that the people were all a bit chunky and heavy and they all had several very heavy cabin bags each...With a full load and with the fixed load sheet weight for each passenger, I'm sure that the actual take-off weight was often quite a bit more than the load sheet take-off weight. The only way to have been sure was to get them and their cabin bags all off and weighed on a scale...This would have caused chaos!!

[blind pew]

One T3 was nearly lost out of Malta at night.
P1 rotated below VR and took out the approach lights with the death rattle going.
It was flown on radio altimeter height, below 50ft, for several minutes with the rattle going in ground effect.
Eventually it burnt enough fuel and began to accelerate.
It was found that the incorrect runway length had been used for the calculation of the T/O data by the office wallahs.
No one had checked it.........no change there then.

Met one of the FOs after he had got his command on the 737 who described the flying as the best he had ever seen.

Re AJ post - there was no 4 engine requirement for BOAC - that was an airtours thing for the 707.

Our BALPA rep, who negotiated the merging of seniority lists fiddled the date so that he could get the 747.
My course was the first to go into BEA after the last course had joined BOAC - which was the correct place to start a joint seniority list - he changed it by two years with the provision that no BEA pilot would be senior to any BOAC pilot re bidding rites!!
Did me a huge favour as I got the Iron Duck - fantastic time.

[Hobo]

Re the Eastern Med, the T3 did the Cairo service (via tech stop Athens) for a month or so in lieu of a 707 (??) in the late 70's.

[Meikleour]

Blind pew: I have sent you a PM

[slast]

Also for the Eastern Med - one early T1 trip was a 6 day epic LHR-FCO-ATH (n/s) ATH-IST (n/s) IST-ANK (n/s) ANK-IST (n/s) IST-ATH (n/s) ATH-FCO-LHR. Not very productive as IST-ANK was only about 200 miles! Later it went to a 3 day trip - 4 legs to ANK on day 1 and a n/s ATH on the way back.

(EDIT: Actually having just looked it up I find that I did it 2 days after the "main gear as airbrake" event which was one of the early points in this thread. Also it was a couple of days before Christmas 66, and in our case we positioned LHR-IST and ATH-LHR on a Comet.)

[TrafficPilot]

What a wonderful thread!

I've spent the last couple of days enjoying reading all your memories of the lovely Trident.

petermcleland you have reminded me what a brilliant "add-on" David Maltby's Trident is for FS2004 and FSX. I've downloaded it again and installed it in FSX.
No "real" flying for me this week due to the holidays so it's been great fun hand-flying some foggy approaches using the Trident and ActiveSky Evolution weather. Nice to see you've retired to a beautiful part of the countryside. We used to have a cottage in Totnes so have spent many a happy time in that part of the South Hams.

One question regarding the Flight Sim version of the Trident which I see you provided information on. Have you noticed much difference in the handling qualities between the Trident 2 and 3 versions? From reading this thread it sounds like the T3 was somewhat more challenging on take-off in "hot and high" conditions?

Regards

Adam "TrafficPilot"

[petermcleland]

Originally Posted by TrafficPilot

One question regarding the Flight Sim version of the Trident which I see you provided information on. Have you noticed much difference in the handling qualities between the Trident 2 and 3 versions? From reading this thread it sounds like the T3 was somewhat more challenging on take-off in "hot and high" conditions?

Adam,

You have caught me out with your simulator question as I normally fly the T3 in my sim. I fly it mainly from my own Flight Sim airport in Alaska, which took me three years to build. Its runway is a bit short for Trident operation and I do have to use the boost engine to get out with full fuel...I suppose I could do it easier with the T2 at its lighter max weight...But I stick to the T3 as it is what I flew till they amalgamated the Trident flights so that we all flew them all.

However, I'm quite sure that the Flight Sim differences between the types will be accurately represented with the correct empty weights and max weights in the config files.

Here are some more old shots that I published a few years back:-

Kick Off Drift...

FSScreenshots.com Forum - Viewing topic #5526 - Kick Off Drift...

Some Technical Aspects of the Trident 3...

FSScreenshots.com Forum - Viewing topic #5527 - Some Technical Aspects of the Trident 3...

Trident Tutorial...

FSScreenshots.com Forum - Viewing topic #5530 - Trident Tutorial...

[Hobo]

Superb stuff, this really brings it all back Pete. Any particular reason for choosing Alaska?

On the first link the kick off drift series is showing the A/C well to the right of the C/L - or it appears to be in these pics.

I find this interesting as I have just been involved with building a 737 Sim (800NG layout in the scrap flight deck of this written off 3/400 freighter). One of the problems we had was correctly lining up the visual with FS2004 ILS. The A/C would be on the ILS, but about halfway between the C/L and left hand edge of the runway visually. We eventually had to use a fiddle factor to the co-ords of the threshold to offset the visual on each R/W we wanted to use.


Back to the Trident...

pedant mode on....

I note in the second link in this last post the pics show the thrust gauges set at 137,137,137. IIRCC the centre was 20 less ie 117 on a normal day. (I think the T1 was 10 less and the T2 15 (?))

...pedant mode off.

[petermcleland]

Originally Posted by Hobo

Superb stuff, this really brings it all back Pete. Any particular reason for choosing Alaska?

On the first link the kick off drift series is showing the A/C well to the right of the C/L - or it appears to be in these pics.

I find this interesting as I have just been involved with building a 737 Sim (800NG layout in the scrap flight deck of this written off 3/400 freighter). One of the problems we had was correctly lining up the visual with FS2004 ILS. The A/C would be on the ILS, but about halfway between the C/L and left hand edge of the runway visually. We eventually had to use a fiddle factor to the co-ords of the threshold to offset the visual on each R/W we wanted to use.


Back to the Trident...

pedant mode on....

I note in the second link in this last post the pics show the thrust gauges set at 137,137,137. IIRCC the centre was 20 less ie 117 on a normal day. (I think the T1 was 10 less and the T2 15 (?))

...pedant mode off.

"A" the autoland was well off centre because of the strong crosswind component...FlightSim can not hold the centreline like the real aircraft did.

I had forgotten about that 20 less for the centre engine...You have to remember that I never flew the Trident as a First Officer, so certain things are a bit hazy. If I had remembered I would have told David Maltby about it and he would have programmed it in. Even so, he has programmed those thrust gauges to be set by just clicking on one of them (this makes all the calculations and then sets the three gauges)...Another piece of Maltby Magic like the Vital Data Card.

A long story about my choice of Alaska...Basically, I liked the wilderness of Alaska and I wanted to build myself an airport...I was flying a light aircraft (in the Sim) along the coast one day and moved just inside the shore and kept my eyes open for a suitable site I came to the end of the Russel Fjord and saw that bay, landed on the beach and said to myself "I will build my airport here!". That was a long time ago and I have been improving and adding things to it ever since!

Here it is working reasonably recently on a Friday (the President sometimes visits on the Thursday when all the F16s are having an R&R day ):-

YouTube - AIBlast1080.wmv

I too have been doing some recent simulation with the 737NG:-

The Final Leg... - iFly Development Team Forums

Cheers,

Peter.

[Wookey]

Happy New Year to all.

Just about caught up with this thread following my short break and surprised at some of the recent posts. Despite the generally positive comments regarding the Trident there are a number of posts during the past two weeks which seem to indicate that Trident's 'Gripper' nickname was extremely apt, almost to the point that the aircraft was inherently dangerous in certain load configurations with hot/short runway complications.

As a passenger (thats what we used to be called before the locost airlines detroyed the mystique of flying and the mutual respect between crew and their charges !!) I never really noticed a lack of climb performance (and I have departed TLV on the 0725), but then I guess only you guys in the front would have known the truth. However in the mid to late 70's I lived on the northern edge of Newcastle about 1 mile due south of the runway and I do clearly remember being amazed at the initial climb out performance of the (then) new Boeing 737s that had entered BA service, when compared to Tridents or 1-11s.

[slast]

Hi Wookey

What you need to bear in mind is that the limiting performance (i.e. what sets the maximum weight that can be lifted off a given runway at a given temperature) is set by what an aircraft can achieve with an engine inoperative, i.e. after a failure at the most critical point on that runway.

The airworthiness authorities define a minimum climb gradient that must be achieved after this failure, and it is not very much! This is a major factor in the manufacturers ability to sell the aircraft and it may be (I don't know) that the 737 had a wider performance envelope (e.g. could operate at maximum weight) off shorter runways and at higher temperatures than the Trident which was after all "optimised" to the BA network, so wouldn't often be exposed to temperatures above about 30deg.

However, fortunately for us all, such failures are extremely rare - failures themselves are rare and for them to happen at the worst point is even rarer. What this means is that on a NORMAL takeoff without a failure, the aircraft actually has the power of one additional engine compared to that needed to make the minimum climb gradient. That translates of course into a much steeper climb since the speed stays the same.

So in the case of a three engined aircraft, it needs 2 engines to make the minimum, but normally has 3, i.e. 50% more power than the minimum. In the case of a twin, it can make the minimum gradient on only one engine, but normally has 2, i.e. twice what is needed. So a twin on a normal takeoff will always climb faster than a three engined aircraft, which in turn will always climb faster than a 4-engined one that only has 33% more than needed. (Not sure how the 1-11 fits into your picture though, I never flew it and it may have not been anywhere near its performance limits).

[Hobo]

the aircraft was inherently dangerous in certain load configurations with hot/short runway complications

Wookey, slast is dead right in his response. Most aircraft will, at times, be operated near or at the limit of their take off performance regarding weight/temp/pressure altitude, and give, apparently, 'poor' performance. But this isn't the case, it's just that when operated nowhere near these limits (which the Trident was most of the time - say on domestic flights) the 'better' performance demonstrated might mistakenly be taken to be the yardstick of acceptable performance.

I can remember seeing the localiser aerials at very close quarters on 4 engined jets at certain hot and/or high airfields when starting a long flight.

Certainly, the Trident was never considered 'inherently dangerous' by those who flew it, quite the contrary.

[Prober]

Wookey,

Steve has given a very succinct resume of climb performance and I never felt that the ‘Gripper’ was dangerous in that respect. The nickname came from the long take-off run it required (thanks to early meddling), but once in the air it was beautiful to fly and it felt like a well worn and familiar glove. I only managed one V1 cut, at GVA so plenty of room. However, even at that speed, the stopping distance raised no eyebrows (except in approval) though there were a few ‘pops’ after taxiing to a stand, plus a small pile of carbon dumped on the tarmac as a souvenir. Lack of fuel space was a drawback and certainly caused me a few nail biting moments, as the T1 and T2 were operated at the extremes of their range. But Wookey, no, I never got the feeling that any of the crew regarded it as dangerous, nor even marginal (except as above).
Prober

[Wookey]

Thanks Chaps, thats reassuring. I have clearly over-reacted to some of the stories posted here. Again, as merely a passenger, I always enjoyed flying on Tridents and have many fond memories of those years.

One further question regarding visual approach procedures. As I mentioned in an earlier post in the 70's I lived in Newcastle and frequently flew LHR - NCL on Tridents. I distinctly remember on a number of occasions arriving in the NCL area (after a speedy flight from HRW) a rapid descent over the city and turning to finals over the A1/Gosforth Park Hotel which would be I would guess only 1-2 miles from the eastern end of NCL's runway. Was this a function of Tridents performance or just another example of the less controlled times we lived in back then?

Jolly exciting for us down the back but the short sector times (sub 40 minutes ?) certainly put pressure on the cabin crew to get the gin & tonics out !!!

[twochai]

I can remember seeing the localiser aerials at very close quarters on 4 engined jets at certain hot and/or high airfields when starting a long flight.

Certainly, the Trident was never considered 'inherently dangerous' by those who flew it, quite the contrary.

While all that is certainly true, 'modern' airliners have, by design, higher power-to-weight ratios and more thermodynamic power in reserve than any of the first generation big jets. This was done to provide more operational flexibility in a range of weight/altitude/temperature situations and made today's aircraft inherently safer as well. The VC-10 was perhaps the first example of such an airplane.

The much improved safety record of modern-day jets and turboprops certainly owes some of this benefit to more installed power.

[Bergerie1]

Twochai,

Even the VC10 made one hold one's breath on occasions. On take-offs from Entebbe at night at max weight when going north to London none of us believed there was enough stopping distance should an engine fail at V1. Crews were so concerned that one of BOAC's performance engineers was sent out to Entebbe to measure the actual performance achieved.

Of course it was correct and we were achieveing the book figures OK. The reason it looked so awful was that there were no obstacles at the end of the runway where the ground sloped down to Lake Victoria and one just seemed to depart into a black hole.

[Wookey]

twochai

Your power to weight ratio theory seems logical to me. I am not an aerodynamicist or aeronuatical engineer but have some limited experience in mechnical engineering.

Presumably the climb performance will be affected by how quickly the wing reaches sufficient airspeed to generate the lift required to get the aircraft mass airborne. Therefore the acceleration from start of roll to lift off speed is the important factor and this is where the power/weight ratio is most important?

In hot/high conditions, the air being thinner, engine performance (as with car engines) becomes compromised therefore slowing the acceleration and extending the point where lift off speed is attained (take off distance required).

Am I on the right track?

With regard to the Trident, the BEA meddling with the original specification and the use of the RR Spey was the cause of the aircrafts 'gripper' reputation?

[ChristiaanJ]

Originally Posted by Wookey

In hot/high conditions, the air being thinner, engine performance (as with car engines) becomes compromised therefore slowing the acceleration and extending the point where lift off speed is attained (take off distance required).
Am I on the right track?

Halfway!
The other half is, that air density also crops up in the lift formula, so at hot/high airfields, you also need more true speed to obtain the same lift.

CJ

[Iron Duck]

But this isn't the case, it's just that when operated nowhere near these limits (which the Trident was most of the time - say on domestic flights) the 'better' performance demonstrated might mistakenly be taken to be the yardstick of acceptable performance.

My father, who sadly died this year, was foreman of the BEA metal plating shop at the Heathrow Engineering Base from around 1959 until he took early retirement at the BEA/BOAC merger. Being his son I was 'plane mad and remember a BEA Trident calendar he acquired for me in around 1964. Fabulous.

During the school holidays he would often take me to work with him and I'd spend the day in the BEA staff canteen at the end of 28L, as it was then, happy with my binoculars and Ian Allan books. I well remember in the late '60's that in comparison to most other types the T1/T2 appeared to have a sparkling climb performance. I well recall a TWA 707 coming off 10R being at only about 50' as it crossed the threshold and barely climbing as it disappeared over Hounslow.

Slightly changing the subject, I also recall seeing on a dark morning a 707 parked outside what was the Air India hangar south of 28L, starting up. It was directly tail-on to me and I clearly saw the combustion chambers in each engine lighting up, making a ring of bright dots. The memory is distinct and clear, but given that they must have been hidden by the turbine blades I have no idea why I should have been able to see them.

I have to say, though, even though this is a Trident thread, that to me the best-sounding aircraft at ground idle was the Iron Duck. It reminded me of a bronze bell. I'll never forget.

[Swedish Steve]

I clearly saw the combustion chambers in each engine lighting up, making a ring of bright dots.

I've seen that on a Trident. In 1974 when I was working at LHR, I was driving around the terminal for a couple of days with a propulsion engineeer. We were parking across the cul-de-sac from each departing Trident while he watched the start up with binoculars to see if the flame propagation was regular. You could see the flame move round the engine from can to can.