Last & Best of the Piston Engine Fighter Aircraft.

[Tommy Cookers]

so that dates the Tempest LF myth back as far as 1970
we need the source material (the bibliography for whatever book started this would do)

the book by Kasmann (with an umlaut) that tells me about the real He 100 also ....
says LF had max thickness at 50 - 60% chord - so the Tempest is not LF and he doesn't classify it as LF


a relevant example of myth genesis ....
lots of books and magazine articles have said since 1967 that the Lotus 49 was the origin of the F1 engine-as-structure
lots of people repeated this and it was/is widely believed
people still want to believe this .....
but the H16 BRM was the origin 2 years earlier (and of course Lotus had H16 BRM engines)

[J.A.W.]

Another remarkable period 'Flight' article - is this translation of a startlingly frank 'Nazi-science' aero-tech review,
(from 1942), which includes matters such as 'laminar-flow', direct injection, & 'meredith effect'..
(& a very NPL/Tempest-like wing profile diagram, for illustrating the L-F process!).

http://www.flightglobal.com/pdfarchive/ ... 00666.html

Anyone who is interested - can compare an overlay of Mustang/Tempest wing profiles,
& see how just how similar they are - for themselves, at the site linked below..
so, once again T-C, clearly - not much "imagining" is required to see the classic 'laminar-flow' shape - in both:
http://airfoiltools.com/compare/

Such an overlay exercise will show that, notwithstanding T-C's emphasis on the lower wing recurve feature..
the Tempest wing profile indeed demonstrates that claims of a "...less sharp LE, less flatness initially..."
actually are - better applied - to the Mustang..

Seems I'll have to reiterate the evidence.. see the period 'Flight' article showing German 'L-F' profile..
No "myths" there.. nor here: http://www.flightglobal.com/pdfarchive/ ... 01127.html

[J.A.W.]

so that dates the Tempest LF myth back as far as 1970
we need the source material (the bibliography for whatever book started this would do)

the book by Kasmann (with an umlaut) that tells me about the real He 100 also ....
says LF had max thickness at 50 - 60% chord - so the Tempest is not LF and he doesn't classify it as LF...

Well T-C, the cited Supermarine claim to a 'L-F' profile wing in the mid `40s is then perhaps also a "myth"?
Since their ~40% chord max-thickness - "is not LF"? http://www.flightglobal.com/pdfarchive/ ... 00767.html

[tok-tokkie]

An interesting thread. Apropos the last posts mentioning received opinion & Lotus. There is a question I would like to pose to you guys which is way off topic but you are a well informed audience.

Simplify & add lightness

This is attributed to Chapman of Lotus. However I am 'positive' that I read years ago about that being a big framed poster in the Curtiss drawing office. I have Googled to get confirmation & it has turned up no corroboration. Any of you able to confirm & give a reference?

[Tommy Cookers]

William Stout (Mr 'Ford' Trimotor ?)
1920s or early 1930s

[J.A.W.]

T-C, according to this link below, wartime German technical appraisal of a captured Tempest: duly noted its 'L-F' wing profile..

http://www.hawkertempest.se/index.php/c ... -s-tempest

[Tommy Cookers]

afaik I have seen this
and don't regard a translator's rendering of a German quick impression of the Tempest as a show-stopper
the source is a Ta 152 book - Kasmann's book says Tank said wte that LF didn't work

btw P238 from your link to the very interesting evolution of the Bristol Freighter mentions the DH prop's section being ....
NACA series 16 ('laminar flow characteristic - less profile drag than Clark Y')


we still lack any official recognition/categorisation of the Tempest wing as LF

iirc official reports re the Spiteful that I linked state/imply cusping or thick trailing edge (as signs of British official LF)
is this seen eg on the Attacker ?


btw the Flight archive mentions re the Goblin a claim that .....
Whittle's reverse flow allowed better diffuser action (pro-Whittle points are a novelty to me)
I wonder then how its compressor working range was so limited

[J.A.W.]

T-C the question is, did Kasmann read the 'L-F' notation in the original Rechlin Tempest report, & properly footnote it?

Or was it based on remarks by the German test pilot H-W. Lerche in his memoir - which was supported by his flight logbook ?

& if it was duly noted as such, in 1945, & not just 'added' by Kasmann, as 'received knowledge' - it would be of interest..

Since the actual descriptive term 'L-F' was largely a matter of sales hype ( improved drag results notwithstanding),
in period Camm would have no reason to be seen as jumping on the NACA 'bandwagon' & claim 'L-F' too,
even if his NPL/'Hawker high-speed wing' profile clearly does show 'L-F' characteristics..

( & the redesigned P-51H adopted a newer 66-series NACA 'L-F' profile wing, but to seemingly little functional benefit).

As for Tank, he was perhaps, an equally adept a salesman - as he was a designer.. his FW 190 used the same semi-antiquated
high lift, but drag-limited @ high-Mach NACA wing profile - as the USN F4U & F6F, in order to get his heavy machine to 'behave' on the smallest feasible wing area, (& he'd already had to increase it, for series production).

AFAIR, RN test pilot E. Brown found the 'L-F' Supermarine Sea Fang 'unsatisfactory' as a carrier machine,
& accordingly, the Hawker Sea Fury ( ironically also 'L-F') - got its gig.

Brown also noted that while pretty much the same wing - was recycled on the 'lash-up' Attacker jet
(unusually for a jet - it retained the wing armament, & 'tail-dragger' undercart)
- it'd had much needed low-speed lift/control devices added.. ( & that wing was small, area-wise too, which didn't help).

Even so, I don't think it spent much time aboard ship, as those carrier skippers didn't want the paint routinely burned
off their flight decks - by the Attacker's blow-torch jet efflux..

[J.A.W.]

Here's an item of topical interest..
..seems a Napier Sabre is intended/being prepared - for (eventual) flight in Blighty, too..
http://hawkertyphoon.com/napier-sabre-engine-secured

[J.A.W.]

Here's one of Kermit Weeks' Sabres - in its original NOS gleaming bakelite-black* finish,
destined for use in his Tempest V - also currently under resto..



*Napier cleverly applied the thermoplastic - as an impervious sealant for major Al engine castings..
something the British motorcycle makers could've usefully emulated, as porosity-leakage prophylaxis..

[wonderpractice]

Check the fine aero-slick detail design of this rare P-51H Mustang, https://www.youtube.com/watch?v=HfPOVWOIL8M
- this the final production model, & a significant 'lightweight' revision.. running an ADI equipped hi-po factory Merlin.

At up to 90" ( +30lbs) boost in mil-spec WEP , for 2,200hp, it would do 400mph @ sea-level, & 428mph at 8,000ft (Reno race height),
- as performance was graphed here: http://www.wwiiaircraftperformance.org/ ... fig16a.jpg

Thanks for the link.

[Badger16]

I'm always amazed by the late war in-line plane piston engines. Shoving 3000 hp in a package that can fly with a pilot, weapons, fuel and armor while being able to be fast and nimble enough for a dogfight is one hell of a feat.
The main downside is evident ; good luck cleaning, repairing or even finding what's wrong with one of these. Plus, as far as I know, both the Tempest's Napier Sabre and Mustang's Merlin were quite sensitive to damage, something which somehow tends to happen to warplanes in active service.

Anyways, I had once the occasion to see one of my favourite warbirds in action ; the Soviet I-153. They're original restored planes, which makes it even better! However, they don't have the original engines, but a variant of them with a differently placed gearbox and no weapon synchronisator since they couldn't find any original model.

[J.A.W.]

Plus, as far as I know, both the Tempest's Napier Sabre and Mustang's Merlin were quite sensitive to damage, something which somehow tends to happen to warplanes in active service....

"Quite sensitive to damage...."

All engines are sensitive to damage, particularly to damage caused by weapons - designed to do so.

But some engines were more robust/tolerant of 'mishandling' by the operator, which can also cause damage,
particularly if the fighter pilot is busy contending with a combat situation, when his machine was lacking
a coordinated control system, & thus required many individual adjustments - to ensure proper operation.

[Tommy Cookers]

mishandling sounds like Gunston's writing - pilots mistrust of 'book' methods for range that ignored plug fouling and vibration
plug fouling increased with moves to eg 115/145 fuel as it had more TEL
a workmate ex-Coastal Command engineer told me fuel mishandling (any engine feedable from any tank) lost patrol aircraft

combat engine mishandling might include deficient radiator shutter handling (as the Duxford 109 accident)

engine combat resilience ?
Don Blakeslee flew a P-47 from overhead Belgium to the UK leaving 2 of its 18 cylinders in Belgium
James Goodson similarly flew a P-51 with no coolant but kept it running by constantly pumping the primer knob

other mishandling ?
many engines eg USAAF not USN in WW2 had manual control of boost and even manual selection of supercharger ratio
so sometimes were run deliberately beyond 'book' power - flying by ear (any detonation is apparent in a single-engine plane)
a Merlin P-51 was flown in high blower 97" at low altitude using the push-and-hold switch provided for ground checks
(presumably why this switch was omitted from RAF 51s - did it exist eg in RAF bombers with Packard Merlins ?)
RAF Allison 51s reached 75" during fighter sweeps over France in late '42-mid '43 - there's an official report
some P-38s (in Iceland ?) were set for more boost than the book said
some B-24s were lost from (under) boosting ie for 91 octane when they had 100 octane in the tanks
detonation from momentarily over-pitching the prop occurs even in modern NA engines
any running-on probably isn't detected as engines are stopped by fuel cutoff
prop pitch ie rpm and power seems to have been set at local level and (I guess) the CO would have had 50 rpm more
Stewart Tresilian's engine development work seemed based on more rpm helping to avoid detonation
remember the Sabre was locally reset for patrol via relatively high boost/low rpm - and kept failing
(this century I knew someone whose oiling blew on takeoff - he tried to keep the engine running but the prop went full-pitch
not useful when turning back to land with 40 mph tailwind - he retracted the flaps, jumped the fence and 'landed' ok outside)
many especially RAF fighters supposedly had no negative g capability due to fuel and oil systems
but John Jordan flew a Spitfire inverted for 8 minutes till the fuel pump seized - and treated a Vickers Windsor similarly
and afaik a local ex Hurricane CO taught for evasion purposes that the stick should be at its full forward full left stop

engine failures were disproportionately frequent after routine inspections/maintenance and at power reduction after takeoff

[J.A.W.]

Great to see a (very rare) P-82 Twin Mustang back in the air, an exceptional machine on several levels.

https://www.youtube.com/watch?v=SnqyflPNTvw