Last & Best of the Piston Engine Fighter Aircraft.

[J.A.W.]

Indeed T-C, with such a strong structure, & a tonne or so of Sabre/Centaurus up front, those big Hawkers
were notable as robustly protective of their occupant/s in the event of a forced landing*.

Re: the Heston-N-N Racer, with a highly polished, finely contiguous surface & max thickness at ~40% chord,
it likely featured more of an actual 'laminar flow' than those service aircraft - which were touted as such..

*Albeit the Typhoon was notorious as a 'bad ditcher', as its wing caused a 'stop-dead' brake effect - on water.

[Tommy Cookers]

again ......

you can't judge whether it's an LF aerofoil by the location of maximum thickness
the conventional high-speed aerofoils of that time could have maximum thickness far aft
you judge it's an LF aerofoil if the maximum change of curvature is significantly aft of the location of maximum thickness
these two points I have shown weeks ago

that's why the Heston isn't LF and the Tempest isn't LF
anyway surface quality is relatively unimportant with non-LF aerofoils but critical with ambitious LF ones

you might compare the Tempest, the Vampire and the ('less ambitious LF') P-63 and A-26 aerofoils by the above criteria

[J.A.W.]

Actually T-C, some months ago you asserted that it was the "cusping" aft of the max thickness point that
determined the 'laminar flow' effect, but whatever, the reduction in drag noted between Tempest & Typhoon,
(as shown in the period era table linked, a couple of posts previously), is remarkable & pointed.

The consensus view, from contemporary sources back in the `40s
( such as the CA 15 article in 'Flight' posted earlier),
- through to those posted on current sites - does not rely on "cusping" as a clinching factor, though - to be fair.

[J.A.W.]

Further to mention of the century old (yet oversquare DOHC 4V) Napier Lion, is this citation in 'Flight',
http://www.flightglobal.com/pdfarchive/ ... 01118.html
which shows how, over 90 years ago, the advent of 'high-test' petrol allowed the (sea-level/unsupercharged)
race-optimised Lion to run at a compression ratio of 10:1 for 880hp, with fuel efficiency of 50 gallons per hour.

Adding supercharging allowed the venerable beast to generate even more power at Bonneville salt flats
( ~1000hp over its original 450hp!),
- & thus to enable John Cobb to wrest the Land Speed Record - from the R-R type R powered machines.

[Tommy Cookers]

cusping or its alternative the blunt TE are not always necessary with an LF aerofoil - so what ?
but the criterion I gave again today always applies - which is why I gave it
presumably you have discovered this undermines your case

and your drag figures don't prove the Tempest aerofoil was LF - what do Spitfire figures show with its non-LF aerofoil ?

[J.A.W.]

Well, T-C the listed Cdo figure for the Spitfire is 0.0229, whereas the Tempest is significantly lower,@ 0.0159,
- so something* is def' happening..

* 'Laminar flow'?

(& its not "my case" T-C, its the current consensus view, have you anything to present - which def' contradicts it?)

[Tommy Cookers]

is Cdo the zero lift drag coefficient ? (the lowest drag coeff possible)

if you fly at zero lift for more than a few seconds you're dead (you have done a parabolic dive into the ground)
it's not a useful figure
what's the Cdo for the Mustang ?

[J.A.W.]

"Cd=Cdo+Cdi"

https://www.grc.nasa.gov/WWW/K-12/airplane/dragco.html

According to the citation you've linked in the post at the bottom of page 2 - of this thread, T-C,
both Spitfire & Mustang are Cdo listed at over 0.0220 - compared in a table for drag rise, at higher Mach.

[Tommy Cookers]

I read the tabulated Tempest Cdo as 0.0199 not 0.0159
as the unclear number doesn't look like other figure 5s
the unclear number's top half is squatter than other 5s top half but matches the top halves of other 9s
and this is a value from the prototype Tempest - the other Cdo values are from production aircraft eg Spit V is 0.021

the production Mustang is 0.0227
the predicted Buckingham is 0.023 - oh yes ?

other sources ie the links I posted on P2 show or mention
eg for the Mustang 0.0163 and 0.018 for the Spitfire
and other plots showing Mustang Cdo quite high and the Thunderbolt's rather low
and the Spitfire's lower than the (LF aerofoil according to you) Meteor's

[J.A.W.]

Agreed, the hand-written numerals are ambiguous in some instances, however it is clear enough that
the Tempest is below 0.02, & its wing is a significant advance in drag reduction over its 'older brother' the Typhoon.

Moreover, the Tempest not only kept its drag advantage over the Typhoon at cruising speeds,
( as the Mustang did - over the comparably powered Merlin Spitfire),
it also maintained that advantage at the high Mach end of the speed range,
in combat functionality - at 550mph EAS, whereas the Mustang developed 'porposing' problems,
at ~ 50 mph less, & with wartime service Spit 'limitation' set at 470mph, it was 'out dived' by both, (+109/190).

[J.A.W.]

...and the Spitfire's lower than the (LF aerofoil according to you) Meteor's.

Meteor wing profile - 'laminar flow'?

I don't think so.. are you sure T-C, that you haven't confused - Vampire - for Meteor?

In any event, both of these 1st gen British jets were below the standard set for high-Mach* combat capability
- already demonstrated by the Tempest, (even if turbines were certainly - the future of high-speed flight).

* As it was, in 1944..

[Tommy Cookers]

the Vampire and the Meteor had the same aerofoil - which you have said is LF
anyway it might be useful to compare it with the Tempest's

my original point was that the MB5 could have done the same job as the Tempest at maybe half the production cost
Beamont's Tempest did 0.87 M but presumably official in-service limits issued were lower (IAS is not a Machmeter)
similarly with Martindale's flights and Powles flew a PR19 Spitfire at 0.94 M or whatever
eg 'my' pilot said there was an advisory placard but no actual numeric limits in his Thunderbolt

the point people miss is that the propeller planes wing loadings were low so that they managed on shortish runways
(though a few designers thought otherwise, that 100 sq ft wing area was enough for a fighter)
the Spitfire had a shorter takeoff than the P-40, and shorter again than the Mustang's .... Tempest's ... etc
the jets speed was allowed to benefit from much longer runways of course

ok the Cdo is indicative of a somewhat artificial type of maximum speed
the Spitfire was designed for maximum climb ie it would beat a Mustang in takeoff then steady climb then steady dive
similarly in steady turning, for the same reason
each pilot would like to fly in the way his plane did best

all aerofoils have some laminar flow
an aerofoil that is called LF will have a lower Cd at some Cls (AoAs) and a higher Cd at others
ok post WW2 flaps will help the pilot to avoid what otherwise would be disadvantageous AoAs

[J.A.W.]

T-C, I have made no claim about the Meteor wing being of the 'laminar flow' type..
But, being a Hawker-Siddeley Group product, would it really have shared the De Havilland wing profile?
Seems doubtful, at face-value - claims by US airfoil listmakers, notwithstanding.

'Flight' on the other hand - noted, that the Meteor was of:
"Aerodynamically conventional design", & "One looks in vain for...laminar flow wings..."

As for the MB-5, it - didn't - feature a 'laminar flow' wing profile,
& could not match the contemporary Hawker Tempest/Fury performance-wise.
( AFAIR, wee 'Winkle' Brown did record Mach 0.87 - in a fully instrumented RAE test Tempest).

There are numerous combat reports by RAF officers using such high speeds in combat inc'
exceeding the Vne 'redline' IAS, with the stoutly constructed Hawker coping well, unlike Spits,
which tended to fold up - when wrested about in combat, at very high speed.

& since the RAF didn't want any new piston-powered fighters, the Martin-Baker was never a 'goer'..

[J.A.W.]

See this link:

http://www.australianflying.com.au/news ... c-fighters

-for a fairly recent pilot's appraisal - of a few of the thread-topical aircraft..

( & interestingly, an opinion is given re: flying characteristics of both 'laminar flow' profile & semi-elliptical planforms).

[Tommy Cookers]

and he clearly doesn't categorise the Sea Fury (and therefore the Tempest) as laminar flow
and he says (as I did) - there's no free lunches with LF airfoils

years after the Tempest the (S.28/43 spec) Blackburn B48 Firecrest had a laminar flow airfoil said Eric Brown
NACA 43017 (mod) root and NACA 64-(3.5)15 tip says that airfoil site (what's 43017mod ?)(64 a conservative '3rd gen' LF)

Brown also said .....
fighter limiting airspeeds were only based on compressibility from 1942 (previously based on aeroelastic effects of course)
Typhoon limiting was 0.79 Mach and critical was 0.81 Mach (he did 0.84 and recovered by 18000 ft)
Tempest 5 limiting 0.81 Mach and critical was 0.83 Mach (doing 'your' 0.87 he nearly died, only recovering at 1500 ft)