J.A.W. wrote: ↑
Thu Jan 06, 2022 9:46 am
Actually T-C, as noted previously - a comparison of critical Mach & Vne limitations listed in the veritable
'Pilot's Notes', & in actual flight as commented on by AFDU*/A & AEE test pilots do emphatically contradict
the assertions of RAE's 'head boffin', indeed Camm felt very let down by the RAE's faulty predictions via
reality, which is why Camm went through the process of redesigning the Typhoon into the Tempest,
(& applying the NPL data-derived wing), as soon as practicable, once Typhoon flight tests failed to show
the RAE's claims held merit in high-speed flight.
(The Bristol Beaufighter was likewise an RAE thick-wing 'fail' for RAE predictions speed/power-wise).
*The AFDU Tactical trial comparison; Tempest vs Typhoon states:
"...the Tempest is as delightful to fly as its smaller contemporaries, & much more pleasant than the
Typhoon. It feels more solid & easier to control than most aircraft at speeds over 400 IAS... It has
the best zoom-climb & dive characteristics yet seen by this Unit."
I do not know what the above has to do with the matters in hand ....
NPL (via their 1933 compressed air tunnel - enabling full Reynolds nos) were the UK experts on aerofoils .....
this faulty tunnel 'wrongly' endorsed via the RAE conduit relatively thick wings (thicker is stronger/lighter of course)
Hawker favoured conservative versatile designs for saleability eg Hurricane had a large wing area and lift coefficient
then NPL designed the UK laminar flow aerofoils via their high speed (non-full Reynolds nos) tunnel ....
my link shows these aerofoils failed to meet expectations but this wasn't discovered till E28/39 tests in late 1940
the Tempest aerofoil was chosen in May 1940
failure to meet expectations meant worse than the Spitfire's (that was thinner of course)
this (unimportance of aerofoil and importance of thinness) was a revelation that stands to this day
as in Morien Morgan's forward to a Spitfire book c.1970 (he was RAE 'head boffin' in 1969 - not 1939)
(the paragraph 'laminar flow wing')
https://www.sciencedirect.com/topics/en ... g/airfoils
these sources state that the LF didn't in the WW2 era succeed in many of the ways then claimed ....
eg alleviating the Mach-related erosion of controllability
at best the LF airfoils gave improved cruise ie lower drag at relatively small lift coefficients
but inferior L:D ratio at high lift coefficients
the reason the Spitfire was unbeatable in a sustained turning match and at altitude
the reason the US said the Tempest was in turning inferior to the Typhoon
a thin wing is a heavier and/or weaker wing that has less lift and more drag much of the time
a LF wing has less lift and more drag much of the time - and inferior Mach no limit unless it's thin
yes the Tempest wing gave a good limiting Mach no 0.87 - but the Typhoon was pretty good (0.84 and lighter iirc)
they were both too heavy and expensive and their engine was too heavy and expensive
a fighter has a 'flight system' that lifts 6 or 7 times (its weight and the 'propulsion system's' weight and the war load)
the war load eg guns etc is a small fraction of the weight of the flight system and the propulsion system ....
so the fighter can only be as good as the power:weight ratio of the PS allows ..... ie ....
the best V12-powered fighter was as good as the Sabre-engined fighter .... because ......
the Sabre-based PS as realised had somewhat inferior power:weight ratio
the best place for the Sabre PS was in the Mosquito II/DH 101 or Hawker P1005 .... because .....
a bomber's 'flight system' lifts 3 times (its weight and the PS's weight and the war load) .... so ....
a more powerful but heavier engine (even with somewhat inferior power:weight ratio) would allow a better bomber ..