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Tim McLelland
16th Jan 2009, 13:22
Okay, it's probably an urban myth but I guess it's worth mentioning -

I recall a well-known aerospace publisher telling me of a tale concerning a Lightning (supposedly at Boscombe Down, I seem to recall) which "inadvertantly" reached an unspecified speed significantly in excess of Mach Two. The aircraft was allegedly either written-off or repaired, but that's all there is to the story.

I have my doubts about if of course and I haven't seen the tale crop-up for years, but, just in case anyone else knows anything about it ... any thoughts?

lightningmate
16th Jan 2009, 16:14
Tim,

I have never heard of any such event. Boscombe is not well placed for supersonic flying airspace and the recovery distance with the inevitably depleted fuel state suggests to me that, at best, a run to M1.8 would be the limit. Like most M2.0 capable aircraft of that vintage, the magic figure was rarely achieved outside of flight test. Acceleration at the top end was quite laborious, so exceeding M2.0 by a significant margin has, to me, the same ring as the very high altitude claims.

The stripped down Mk1As used by the TFFs were generally considered to be the most 'sporty' version.

lm

Tim McLelland
16th Jan 2009, 17:04
Oh I quite agree that it sounds a tad unlikely! The only reason I have never dismissed the story is because it came from a reputable source (someone who had a lot of contact with Lightning people), but of course this is no guarantee that the story was entirely accurate!

Incidentally I wouldn't dismiss the altitude claims quite so readily - I can think of a few former Lightning pilots who will confidently claim some fairly hair-raising figures!

safetypee
16th Jan 2009, 23:12
Tim,
My version of the story is that during an F3 airtest – probably from Leconfield, a pilot (of small stature) conducted a high speed run (M1.8+) followed by a zoom climb.
Having zoomed to a very high altitude on a previous flight – 93K claimed, one lesson learnt was that the pitch controls become increasingly ineffective in the rare atmosphere and low airspeed. Thus during the airtest, roll control was used to invert the aircraft and the nose ‘pulled’ below the horizon, unfortunately the nose attitude was well down and the Mach No increased rapidly before the airspeed limit was reached. Also without missiles, the cg/pitch feel may have been different.
The exact Mach No achieved in the dive was not disclosed but M2.2 was suggested; in addition to melting the tail nav lights (usual occurrence above M1.8), the glass windscreen was a bit wrinkly from the heat.

For a M2.0 operational clearance, I assume that the release to service flight tests went faster; e.g. for the airspeed limit of 650kts, I understand that 700kts was cleared.

IIRC the Mk 1s (small fin aircraft) were limited to M1.7 as at high Mach No they tended to go sideways, so an overspeed run was not advisable. Also, some of the early ‘hand built’ aircraft could suffer intake buzz at high Mach. But for time to height and acceleration, a lightweight Mk1 was fantastic.

Tim McLelland
16th Jan 2009, 23:33
Hmm, that might well be the basis of the story, then. I'm surprised that such tales haven't been circulated much more, considering the many other (less hairy) tales which have gone around for years. It's odd that various people have claimed some fairly impressive altitudes for the Lightning but rarely has anyone mentioned maximum speeds over the years.