Perf Group A history
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Following the link given by IGh (post #37) to the US DOT archives, some reading during a snowy afternoon has led me to:
CAR 4 dated May 31, 1938: no mention of V speeds;
CAR 4 dated August 15, 1942: para 04.75320-T defines V1 and V2. This para did not exist in the 1938 document. The "-T" means the requirement applies to Transport Category airplanes. No mention of VR - interesting, as nosegear transports were around by then. (DC-4E 1938, C-54 Feb 1942, military though intended for airline use). I suspect that propliners did not need much of a "rotate" - just a gentle nose-up to leave the ground.
Still no mention of VR in CAR-PART4b of 1953. Perhaps VR came in with the jets?
That 1942 document also includes the first (that I have found) requirements for engine-out continued take-off from V1.
So, I think we can conclude that the beginnings of the modern performance certification date from the US DOT rules of 1942. Interesting - rather earlier than I had thought.
Also interesting is how long developments continued - e.g. aterpster's reference above to lateral clearance of obstacles. Is change still going on to these regs?
CAR 4 dated May 31, 1938: no mention of V speeds;
CAR 4 dated August 15, 1942: para 04.75320-T defines V1 and V2. This para did not exist in the 1938 document. The "-T" means the requirement applies to Transport Category airplanes. No mention of VR - interesting, as nosegear transports were around by then. (DC-4E 1938, C-54 Feb 1942, military though intended for airline use). I suspect that propliners did not need much of a "rotate" - just a gentle nose-up to leave the ground.
Still no mention of VR in CAR-PART4b of 1953. Perhaps VR came in with the jets?
That 1942 document also includes the first (that I have found) requirements for engine-out continued take-off from V1.
So, I think we can conclude that the beginnings of the modern performance certification date from the US DOT rules of 1942. Interesting - rather earlier than I had thought.
Also interesting is how long developments continued - e.g. aterpster's reference above to lateral clearance of obstacles. Is change still going on to these regs?
Last edited by kenparry; 28th Feb 2018 at 17:38. Reason: last 2 sentences added
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If you are a 135 operator without a performance dept., and instead use APG, it will be a takeoff flight path predicated on AC 90-121. I suppose Jepp's data department does the same.
Psychophysiological entity
I walked out of the performance exam 23 minutes after I walked in. It was somewhat to the surprise of the invigilators and the result of the most incredible bit of luck. I needed a pass in four days from scratch to get my first job and 3 quid for a fast track marking saw me on Channel Airways' DC3 training by Thursday. ARB's pre-passed on a mass of aircraft thanks to "Pop Speller's notes."
Despite seemingly having a natural ability with graphs, I had an instinctive belief that Performance A was a total nonsense. While on an extended vacation in Texas I stayed in aviation pioneer Col Carl Crane's* cabin in the Texas hills. He invited me to test fly his blind landing prototype on numerous occasions. While looking through his work I noticed a patent he held which advised pilots of the distance remaining/passed of the runway during T/O or Landing. I realised that his notion of selling receivers worldwide was unnecessary, as most aircraft had 75MHz receivers which fed audio to the pilots. I further realised that the tone could be replaced with not only the audio of distance readout, but a code which could be fed into a performance computer. I came back to the UK with an agreement that he would have the American market and I would have the rest of the world.
I sent extensive text and plans to the ?? government development board ?? (something like that.) They typically put in 50% on such projects. After some weeks I was knocked back to be told that they were already funding a project that was too similar to allow my application - which they were otherwise intrigued by. Quite a blow.
Co-location of DME's would have seen a quick end to multi lobe 75MHz transmitters. I smile now at my naïveté.
It seemed there was a BAC 1-11 charging up and down a runway somewhere using Doppler to measure the progress. It seems it worked . . . until it didn't, losing all reference to the progress. IIRC, their readout was a second needle on the ASI. Rather more basic than my making use of a multi-functional radar screen. I'd gained Marconi's interest in that at a science display in Alexandra Palace. Not many people were interested in TV screens in aircraft back then but there was a lot of redundancy in the radar unit's capabilities - not least of all a continuous wind velocity vector during approach.
The BAC 1-11 project devoured funds and was wound up.
Every so often over many years I would experience bewildering issues with performance. One vivid memory was being with my Fleet Manager, so it must have been a windless and fine day. We left Spit on what I deemed to be a marginal runway but the concrete slabs were so misaligned/heaved, that the crashing vertical input was thunderous. I pushed the power to the stops about half way along, and called V1 as we staggered over the rocks. The concept of energy-sucking vertical 'noise' being introduced was not in any graph I remember. Nothing was done. Nothing was ever said.
Forty years later I'm still reading of fence-scraping take-offs. It's not just my misguided gut feeling is it? So many V1 calculations have to be nothing short of ludicrous.
*There's a lot about Col Carl Crane on t'net. He fell out of the clouds in a biplane with a senator's son on board. He devoted much of his life after that teaching people they can't fly in cloud without instruments. He was a guest speaker at Randolph Advanced Instrument flying school in Texas where his talks left the young pilots spellbound.
Despite seemingly having a natural ability with graphs, I had an instinctive belief that Performance A was a total nonsense. While on an extended vacation in Texas I stayed in aviation pioneer Col Carl Crane's* cabin in the Texas hills. He invited me to test fly his blind landing prototype on numerous occasions. While looking through his work I noticed a patent he held which advised pilots of the distance remaining/passed of the runway during T/O or Landing. I realised that his notion of selling receivers worldwide was unnecessary, as most aircraft had 75MHz receivers which fed audio to the pilots. I further realised that the tone could be replaced with not only the audio of distance readout, but a code which could be fed into a performance computer. I came back to the UK with an agreement that he would have the American market and I would have the rest of the world.
I sent extensive text and plans to the ?? government development board ?? (something like that.) They typically put in 50% on such projects. After some weeks I was knocked back to be told that they were already funding a project that was too similar to allow my application - which they were otherwise intrigued by. Quite a blow.
Co-location of DME's would have seen a quick end to multi lobe 75MHz transmitters. I smile now at my naïveté.
It seemed there was a BAC 1-11 charging up and down a runway somewhere using Doppler to measure the progress. It seems it worked . . . until it didn't, losing all reference to the progress. IIRC, their readout was a second needle on the ASI. Rather more basic than my making use of a multi-functional radar screen. I'd gained Marconi's interest in that at a science display in Alexandra Palace. Not many people were interested in TV screens in aircraft back then but there was a lot of redundancy in the radar unit's capabilities - not least of all a continuous wind velocity vector during approach.
The BAC 1-11 project devoured funds and was wound up.
Every so often over many years I would experience bewildering issues with performance. One vivid memory was being with my Fleet Manager, so it must have been a windless and fine day. We left Spit on what I deemed to be a marginal runway but the concrete slabs were so misaligned/heaved, that the crashing vertical input was thunderous. I pushed the power to the stops about half way along, and called V1 as we staggered over the rocks. The concept of energy-sucking vertical 'noise' being introduced was not in any graph I remember. Nothing was done. Nothing was ever said.
Forty years later I'm still reading of fence-scraping take-offs. It's not just my misguided gut feeling is it? So many V1 calculations have to be nothing short of ludicrous.
*There's a lot about Col Carl Crane on t'net. He fell out of the clouds in a biplane with a senator's son on board. He devoted much of his life after that teaching people they can't fly in cloud without instruments. He was a guest speaker at Randolph Advanced Instrument flying school in Texas where his talks left the young pilots spellbound.
Still no mention of VR in CAR-PART4b of 1953. Perhaps VR came in with the jets
kenparry:
It says here: Fuselage tanks = 96 gals. Inner wing tanks 2x53 gals = 106 gals. Outer wing groups 2x64 gals = 128 gals. Total internal 330 gals.
Wing drop tanks 2x100 gals = 200 gals. (I never flew with underwing tanks).
It says here: Fuselage tanks = 96 gals. Inner wing tanks 2x53 gals = 106 gals. Outer wing groups 2x64 gals = 128 gals. Total internal 330 gals.
Wing drop tanks 2x100 gals = 200 gals. (I never flew with underwing tanks).
The course and the exam were indeed based on the Britannia. It was necessary to extract figures from a set of graphs, and then use these figures to DRAW a graph from which you got your MTOW and V1/VR ratio.
The two day Performance part of the course was run by a white dust coated "gentleman" who was a bit younger than we thirty year olds. He looked down upon us Colonials with obvious disdain and we could pick that.
After going through the charts in the AFM he then led us through the construction of these charts. This was superfluous as far as we were concerned particularly as he treated us like children.
The second day was coming to an end and we were getting irritable with his attitude. He then handed out an examination paper requiring the drawing of performance charts. We all got varying answers and he got angry and sulked.
"You are not leaving this room until you get the answers right" he snarled.
"You can go and get F#*`cked" said our flight commander, a Squadron Leader who did not mince words. "Come on chaps, we are off to the pub" he said and we all trooped from the room muttering about two days of wasted time with this clown. The Chief Test pilot at Woodford, Jimmy Harrison, quietly agreed with us after he heard what had happened. We later heard via the grapevine that the white coated gentleman was pulled off lecturing Performance courses
Last edited by Centaurus; 2nd Mar 2018 at 12:38.
Your Vampire speeds are lower than I recall; I do remember 100kt as the threshold speed for landing, and there's a vague memory of about 110kt for lift-off. This was the T11 with no external
Thread Starter
Another snowy day, another opportunity to read into the background.
Little progress with the UK's BCARs; there seems to be nothing on line. The National Archives list thousands of documents, hardly any digitised, so the bulk only available by visiting Kew to search and read.
For the US records, though, very different. Following up the link to the DOT archives, there is a treasure trove of material, and a few hours of reading has found some gems.
SR-422A, issued July 2, 1958, and effective for Type Certificates dated after Sep 30, 1958, includes the following significant changes:
1. introduction of VR
2. introduction of all-engine TODR
3. take-off flight path extended to 1500 ft above the field.
The preamble to SR-422A includes lengthy discussion of its changes from the earlier SR-422. Found here DOT Online Database)
In 1959, SR-422B was introduced, effective Aug29, 1959. Strangely, this does not appear in the DOT archive. The only online record I have found is of para 4T.122, which refers only to landing distance. Was that all there was? I would have thought it to be a complete rewrite of SR-422A.
Some certification dates:
Comet, 22 Jan 1952. The Comet was not bought by any US operator, so was not certificated in the US.
B707-120, Sep 18, 1958 (USA). DC-8, Aug31, 1959 (USA)
Thus it seems that the B707-120 was certified to SR-422, the DC-8 to the later SR-422B.
Little progress with the UK's BCARs; there seems to be nothing on line. The National Archives list thousands of documents, hardly any digitised, so the bulk only available by visiting Kew to search and read.
For the US records, though, very different. Following up the link to the DOT archives, there is a treasure trove of material, and a few hours of reading has found some gems.
SR-422A, issued July 2, 1958, and effective for Type Certificates dated after Sep 30, 1958, includes the following significant changes:
1. introduction of VR
2. introduction of all-engine TODR
3. take-off flight path extended to 1500 ft above the field.
The preamble to SR-422A includes lengthy discussion of its changes from the earlier SR-422. Found here DOT Online Database)
In 1959, SR-422B was introduced, effective Aug29, 1959. Strangely, this does not appear in the DOT archive. The only online record I have found is of para 4T.122, which refers only to landing distance. Was that all there was? I would have thought it to be a complete rewrite of SR-422A.
Some certification dates:
Comet, 22 Jan 1952. The Comet was not bought by any US operator, so was not certificated in the US.
B707-120, Sep 18, 1958 (USA). DC-8, Aug31, 1959 (USA)
Thus it seems that the B707-120 was certified to SR-422, the DC-8 to the later SR-422B.
Thread Starter
Centaurus: thanks for that. The F1 must have been much lighter than the T11. Incidentally, I spent my teenage years living about a mile from the end of the Woodford runway, watching Canberras, Shackletons, and Vulcans going past our house. That was what led me towards aviation - though I never flew any of those types.
Moderator
Another snowy day, another opportunity to read into the background.
And, from the dates, one can see the tie up with the ICAO PAMC development mentioned earlier. As far as I am aware, that was the pivotal development in accelerating things in the performance arena.
And, from the dates, one can see the tie up with the ICAO PAMC development mentioned earlier. As far as I am aware, that was the pivotal development in accelerating things in the performance arena.
https://www.flightglobal.com/pdfarch...59 - 2700.html
NEW CODES FOR TAKE-OFF
Hammered out at the I.C.A.O. Airworthiness Committee meeting in Stockholm during July and August 1959 were new aircraft performance requirements that now only await the Organization's full approval before they become the basis for new national airworthiness codes. Among the most significant aspects of the Committee's work has been that on take-off for which a complete new range of terms—already airline pilots' jargon—has been conceived. The following explanation is condensed from the Monthly News Bulletin published by I.F.A.L.P.A.
The take-off case today is largely dominated by the requirement that the aeroplane must leave the ground at 1.15 (piston engine) or 1.2 (jets) times the power-off, free air stall. The essential difference in the case of the new code is that this condition is not required to be met until the aircraft is 35ft above the runway. Thus, between the surface of the runway and 35ft is a segment not protected by a 15-20 per cent margin above the stall. But other protection provided by the new specifications is claimed to be as good, and certainly to be adequate to prevent difficulty in getting airborne or sinking once in the air. But an exact comparison of the old and the new specifications is complex since the datum and the technique applied to take-off have been fundamentally changed.
The important speeds associated with the old take-off were (1) the stall (VSI); (2) the minimum control speed (VMC); (3) the decision or power-failure speed (V1); (4) the take-off safety speed (V2); (5) tlie initial climb speed (V2 or V2+,). There were various connecting links between these speeds but, as indicated above, the one usually dominant was that V2 had to have a 15 per cent (pistons) or a 20 per cent (jets) margin above the stall.
The important speeds associated with the new take-off are: (1) the stall (now Vs); (2) the minimum control speed (VMC); (3) the engine failure recognition speed (V1); (4) the minimum unstick speed (VMU); (5) the rotation speed (VR); (6) the unstick or lift-off speed (VLOF); (7) the minimum take-off safety speed (V2 min) and (8) the initial climb speed (V2). Space does not permit the full description of all these terms but the overriding points to be borne in mind are that lift-of (VLOF) is governed by 12 per cent above minimum unstick (VMU) and is—in the normal case—assisted by ground effect; and V2min (the old V2), with its 20 per cent (jets) margin above the free air, power-off stall, is now not specifically required till 35ft is reached.
The important newcomers are VMU, VR and VLOF and their connection is as follows. Unstick or lift-off and all speeds up to the 35ft height point (at which V2 min is reached) are mainly dominated by VMU. This is a speed used only in certification trials and is the lowest speed at which the aeroplane can be made to leave the ground and climb away safely. This should, of course, be substantially above the stall but it is difficult to relate to the stall because (1) most aircraft gain from ground effect (usually considered to apply up to half wing span height) and it may therefore be possible to unstick at or very near to the stall, which is a free-air power-off figure; and (2) the stall itself, as measured in U.S. certification trials, is not the same as the stall known to pilots and can, in fact, be much less (Comet 4, 5 kt; DC-7, 7 kt; KC-135, 9 kt). Anyhow, the fact remains that a test pilot must demonstrate that, for various weights, the aircraft can be made to unstick at VMU. This figure is then multiplied by 1.12 to give the lift-off speed. This is 'the speed at which the aircraft first becomes air-borne' and is the speed applied in the normal operational take-off.
The rotation speed (VR) is the lowest speed at which the nose gear should leave the ground. However, the rotation speeds currently being applied to jets are based on the American SR-422 code and thus associated with the old V2 (usually VR=V2 less 5-10 kt), while the new rotation speed (which will probably be applied to all jets in the very near future) is not directly related to V2 but to VMU, as described above. It is also related to the stall (1.1 VS) and to the minimum control speed (1.05VMC) but these will not usually be dominant.
Summarizing, once the nose gear has been raised at a speed between VR and VLOF the aircraft should climb away, reaching V2 min speed by 35ft or earlier. On leaving the ground the most likely dominant protection is the 12 per cent above the 'worst leaving condition' (VMU) and at 35ft the dominant protection is approximately the same as we have always had at the old V2, though with perhaps a small loss due to slipstream effect being greater than the 5 per cent allowed for as between the 1.15 VS1 (piston) and 1.2 Vs1 (jet) specification.
Hammered out at the I.C.A.O. Airworthiness Committee meeting in Stockholm during July and August 1959 were new aircraft performance requirements that now only await the Organization's full approval before they become the basis for new national airworthiness codes. Among the most significant aspects of the Committee's work has been that on take-off for which a complete new range of terms—already airline pilots' jargon—has been conceived. The following explanation is condensed from the Monthly News Bulletin published by I.F.A.L.P.A.
The take-off case today is largely dominated by the requirement that the aeroplane must leave the ground at 1.15 (piston engine) or 1.2 (jets) times the power-off, free air stall. The essential difference in the case of the new code is that this condition is not required to be met until the aircraft is 35ft above the runway. Thus, between the surface of the runway and 35ft is a segment not protected by a 15-20 per cent margin above the stall. But other protection provided by the new specifications is claimed to be as good, and certainly to be adequate to prevent difficulty in getting airborne or sinking once in the air. But an exact comparison of the old and the new specifications is complex since the datum and the technique applied to take-off have been fundamentally changed.
The important speeds associated with the old take-off were (1) the stall (VSI); (2) the minimum control speed (VMC); (3) the decision or power-failure speed (V1); (4) the take-off safety speed (V2); (5) tlie initial climb speed (V2 or V2+,). There were various connecting links between these speeds but, as indicated above, the one usually dominant was that V2 had to have a 15 per cent (pistons) or a 20 per cent (jets) margin above the stall.
The important speeds associated with the new take-off are: (1) the stall (now Vs); (2) the minimum control speed (VMC); (3) the engine failure recognition speed (V1); (4) the minimum unstick speed (VMU); (5) the rotation speed (VR); (6) the unstick or lift-off speed (VLOF); (7) the minimum take-off safety speed (V2 min) and (8) the initial climb speed (V2). Space does not permit the full description of all these terms but the overriding points to be borne in mind are that lift-of (VLOF) is governed by 12 per cent above minimum unstick (VMU) and is—in the normal case—assisted by ground effect; and V2min (the old V2), with its 20 per cent (jets) margin above the free air, power-off stall, is now not specifically required till 35ft is reached.
The important newcomers are VMU, VR and VLOF and their connection is as follows. Unstick or lift-off and all speeds up to the 35ft height point (at which V2 min is reached) are mainly dominated by VMU. This is a speed used only in certification trials and is the lowest speed at which the aeroplane can be made to leave the ground and climb away safely. This should, of course, be substantially above the stall but it is difficult to relate to the stall because (1) most aircraft gain from ground effect (usually considered to apply up to half wing span height) and it may therefore be possible to unstick at or very near to the stall, which is a free-air power-off figure; and (2) the stall itself, as measured in U.S. certification trials, is not the same as the stall known to pilots and can, in fact, be much less (Comet 4, 5 kt; DC-7, 7 kt; KC-135, 9 kt). Anyhow, the fact remains that a test pilot must demonstrate that, for various weights, the aircraft can be made to unstick at VMU. This figure is then multiplied by 1.12 to give the lift-off speed. This is 'the speed at which the aircraft first becomes air-borne' and is the speed applied in the normal operational take-off.
The rotation speed (VR) is the lowest speed at which the nose gear should leave the ground. However, the rotation speeds currently being applied to jets are based on the American SR-422 code and thus associated with the old V2 (usually VR=V2 less 5-10 kt), while the new rotation speed (which will probably be applied to all jets in the very near future) is not directly related to V2 but to VMU, as described above. It is also related to the stall (1.1 VS) and to the minimum control speed (1.05VMC) but these will not usually be dominant.
Summarizing, once the nose gear has been raised at a speed between VR and VLOF the aircraft should climb away, reaching V2 min speed by 35ft or earlier. On leaving the ground the most likely dominant protection is the 12 per cent above the 'worst leaving condition' (VMU) and at 35ft the dominant protection is approximately the same as we have always had at the old V2, though with perhaps a small loss due to slipstream effect being greater than the 5 per cent allowed for as between the 1.15 VS1 (piston) and 1.2 Vs1 (jet) specification.
Before Vmu ground stalls were possible...that's the original takeoff accident
A bit off topic the original landing accidents in Jets was high sink rates on the Approach
A bit off topic the original landing accidents in Jets was high sink rates on the Approach
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A trick - sorry, I mean procedure - we used on the B732 was 'improved climb'. If excess runway length was available we would calculate a higher VR and V2 to get a better L/D to improve 2nd segment engine-out gradient. I can't remember how we calculated the V-speeds and extra RTOW from the T/O perf manual data. A graph maybe?
Another dodge - sorry, procedure - to achieve higher RTOW was to visually avoid obstacles penetrating the nominal engine-out climb-out path if the weather was suitable. IIRC Naples R24 was an example.
So, did IC arrive at the same time as Perf A?
Another dodge - sorry, procedure - to achieve higher RTOW was to visually avoid obstacles penetrating the nominal engine-out climb-out path if the weather was suitable. IIRC Naples R24 was an example.
So, did IC arrive at the same time as Perf A?
