View Full Version : Comet IV

18th Apr 2018, 23:19
Way back in the 60's, I used to spend my weekends sat on top of pier B at MAN watching the comings and goings of many different types of aircraft.

One aircraft that caught my imagination was the Comet IV and this was mainly due to its unusual take-off run. within a very short take-off run the nose wheel would raise and the remainder of the take-off run would be completed in this configuration.

Does anyone have an explanation for this.

19th Apr 2018, 01:23
I did look this up a few months ago. I recall the nosewheel was lifted off at 80 knots and further acceleration took place in that attitude. Was never able to ascertain the "why". It was a procedure used on other British jets, the Vampire being one. The Vr concept was introduced after the first two Comet crashes, which were accounted for by the inability to accurately assess the attitude using the 80 knot procedure, leading to excessive nose high attitude with the result the drag never allowed the aircraft to accelerate to flying speed within the runway confines, or it became airborne in a stalled state.

19th Apr 2018, 01:37
Maybe the need to present a 'positive' angle of attack to the airflow?
Many 3-axis microlights need to start takeoff with the stick hard back to do likewise, one being the Shadow.

19th Apr 2018, 13:37
As it was at Manchester where it reported to rain a lot. It is possible he was using the nose wheel skimming technique to avoid ingesting the wake from the nose wheel into the engine intakes.

19th Apr 2018, 13:57

19th Apr 2018, 15:04
2 very early comet 1 accidents were attributed to raising the nose wheel too early and the airframe and wing then basically stalled the lift needed losing any increased speed in the roll and the a/c just went off the end without getting airborne or very little height gained as in Rome CIA accident
I read a design change of the leading edge of the Comet wings was the solution to this problem and take off handling changes - is that so?

(as mentioned the movie cone of silence was no doubt based on these crashes)

BOAC lost one at Rome Ciampino no fatalities but a nasty one at KHI with CPair on delivery on its way to SYD

19th Apr 2018, 15:21
as an aside 7 Comet 1's were lost in the first 2 years of pax ops

3 structural failures (one during climb in a TS out of CCU and 2 in the later climb due metal fatigue Elba and Stromboli)
2 failed to get airborne CIA and KHI CPair
1 landing over run Dakar UAT
1 taxiing to take off accident CCU

BOAC Comets lost

4th May 2018, 16:43
I flew the Comet 4B with BEA (now BA shorthaul) in the 1960s so my memory is struggling but I am fairly sure the nosewheel was raised at 80 kts to 'skim' the runway in order to reduce the vibration from an out of balance nose wheel.

The nose gear leg was relatively slender and some shake could often occur in the flightdeck on getting airborne so raising the nosewheel off the runway at relatively low speed kept it to a minimum.

The 4B was a completely different animal to the original 1s, with different engines and longer fuselage. The leading edge of the wing may also have been different. It had a number of traps for the unwary, not least being Mach tuck at .83 which was horribly close to the cruise speed of .79. It could often reach coffin corner too. We used it into Berlin Templehof one winter and I think we could manage a respectable 330kts in the corridors.