Last & Best of the Piston Engine Fighter Aircraft.

[Tommy Cookers]

so ....
no production Tempest ever had 3500 hp - or more than 3055 hp
(and no-one believes otherwise - because no-one has found any evidence)

... The Tempest F.6 was the final Tempest mark produced by Hawkers, & incorporated various airframe
improvements airframe developed via the F.2, & by use of the latest Sabre V, with an available
+15lb boost on usual 100/130 avgas - for normal postwar/peacetime use - sans the addition of ADI.

glad to see that you now agree .....
(that 3500 hp is nothing to do with any Tempest ever sold)


btw
the dry weight of the Sabre VI was 2660 lb - it was 'fan-cooled' for annular radiators
though still a single-stage supercharger
the total weight (of what we can call the 'propulsion system') was 4465 lb (180 lb more than the Sabre VA's)
the intended output at low speed was 3350 hp and so presumably consistent with c. 3500 hp at high speed
Roy Gasson of Napier Heritage Trust said the VI wasn't tested (before the Ministry's 1947 Sabre transfer to RR)

btw 2
I met in my work 'Bob' Boyle (afaik now) the 'Bob' Boyle who had worked for and later wrote a book on Napier and ...
maybe I missed a chum's standing invite to meet 'Mr Gliding' & ex-Tempest pilot Derek Piggott at (ex-Tempest) Lasham

[J.A.W.]

glad to see that you now agree .....
(that 3500 hp is nothing to do with any Tempest ever sold)


btw
the dry weight of the Sabre VI was 2660 lb - it was 'fan-cooled' for annular radiators
though still a single-stage supercharger
the total weight (of what we can call the 'propulsion system') was 4465 lb (180 lb more than the Sabre VA's)
the intended output at low speed was 3350 hp and so presumably consistent with c. 3500 hp at high speed

Not at all, (did you read my post T-C?) Once cleared for flight status by passing the type-test,
it was de rigueur to fly them, (if Rotol had provided a prop that could hack that 3,500 hp T.O!)

Of course it was "sold" - to HM Govt, you don't imagine EE/Napier & Hawker paid for them - do you!

The makers still had to fulfill the work for which they'd been paid. Such as completing the batch
of unwanted Spitfire 21 production, which was promptly reduced back to parts after being tested...

The only twin to fly with Sabre-power was the Warwick, which was regarded as underpowered even
when fitted with P & W R-2800s, but was in danger of being 'flayed alive' by a brace of Sabres which
were capable of exceeding the fabric-skinned Vickers machine's VNE @ Vmax...

[Tommy Cookers]

so now all piston engine fighter aircraft (however non-standard or imaginary) are eligible for this thread's 'award' ?

how convenient for you ! (again 'changing the rules')

[J.A.W.]

so now all piston engine fighter aircraft (however non-standard) are eligible for this thread's 'award' ?

Well of course T-C, that's the premise of the bloody thread going way back to page 1!
(If by "non-standard", you mean as in mass production/service & not prototype to service standard).
Or have you forgotten that you were - back then - championing the sole Martin-Baker M-B 5?
(& assumed its wing profile as L-F, which it never had, unlike Tempest/Fury/Hornet/Spiteful/CA-15).

[Tommy Cookers]

then hundreds of planes that actually exist today beat any Tempest ...

but no !
eg Cook Cleland's double Bendix Trophy winning 4500 hp Corsair was apparently ruled out by you

[J.A.W.]

then hundreds of planes that actually exist today beat any Tempest ...

but no !
eg Cook Cleland's double Bendix Trophy winning 4500 hp Corsair was apparently ruled out by you

Doubt it would've beaten a Tempest 6 fitted with the Sabre which passed the 100 hours @ 3,750 hp test..

As both Len Setright & Bill Sweetman duly noted in print (The Power to Fly/High Speed Flight).

Edit: Correction of author's name/reference.

[J.A.W.]

...the Sabres smaller bore and much shorter stroke would seem ideal for poppet valves
(given the fuel quality revolution)
Sabre funding was maintained both to keep a sleeve-valve foot in the liquid-cooled door,
and a reserve engine for the Vulture.

As regards this view T-C, which you have reiterated in this thread, you might find this
period graph to be of some interest since it shows the Sabre's architecture did in fact
suit the volumetric efficacy of sleeve valves, versus big 2V hemi/4V pent-roof poppets...

(pdf courtesy of member here, 'snowygrouch').

[Tommy Cookers]

...the Sabres smaller bore and much shorter stroke would seem ideal for poppet valves
(given the fuel quality revolution)
Sabre funding was maintained both to keep a sleeve-valve foot in the liquid-cooled door,
and a reserve engine for the Vulture.

As regards this view T-C, which you have reiterated in this thread, you might find this
period graph to be of some interest since it shows the Sabre's architecture did in fact
suit the volumetric efficacy of sleeve valves, versus big 2V hemi/4V pent-roof poppets...

(though I don't see what that has to do with the Sabre architecture) ....

the main 'American 2 valve poppet' engine then was the 1820 Wright Cyclone (made for 25+ years)
conveniently for this discussion it had the same bore:stroke ratio as the Bristol engines shewn
but more impressively the later Cyclones at takeoff ran at 2800 rpm - ie 16.3 m/sec or 3850 ft/sec mean piston speed
and the Cyclone supercharger efficiency was improved from 60% to 75% during WW2 - and more post-war
this improvement (as I said before) relieved the suggested problem of poppet valve breathing
over a few years the 1820 Cyclone doubled in power


logic says (though authors don't think of this) that historical improvements in strength ....
(allowing more piston acceleration/rpm but demanding relatively bigger ports/valves at some point)
imply that the ideal bore:stroke ratio would have increased over the years
ie that the old low bore:stroke ratio engines were right for their times

because (strength considerations say) rpm can increase in proportion to the square root of a stroke reduction ....
reduced cylinder volume (eg given bore:stroke ratio) increases breathing (relatively) of both sleeve-valve and poppets
reduced cylinder volume (eg given bore:stroke ratio) increases rpm so increased breathing is handy
these were the basis of Ricardo's and Heron's US Hyper program suggestions ie improving the volumetric 'efficiency'
ie displacement per unit time was raised by raising rpm - but unlike motor sport WW2 didn't have any engine rules

and increased bore:stroke ratios (as Napier) ie tend afaik to reduce the sleeve-valve's breathing (relatively)
(the port height reducing with stroke so port area doesn't rise with rpm rise)
though increased bore:stroke ratios (as Hyper) does increase the poppet-valve's breathing (relatively)
(so only 2 poppets were deemed necessary)

presumably cylinder size/bore:stroke reduction would allow poppet valve breathing to equal sleeve valve breathing
the Sabre was apparently intended for 4000 rpm but only got there via a convoluted and protracted route

[J.A.W.]

Sabre III produced for FAA usage was a dedicated low-level 4,000 rpm variant.

(Presumably also intended for the projected 'Sea Typhoon', prior to the FAA
being liberally supplied with USN F4U/F6F fighters via 'Lend-Lease').


The engines shown in the graph were indeed low-boost, pre-100/130 avgas units.

Being a few % oversquare in B X S, the Sabre was close to ideal in port time/area,
esp' given the boost level increases, which showed advantages in significantly higher
BMEP, & interestingly enough - smoother running too - according to pilot's reports..

The nearest equivalent US 'Hyper program' engine would likely be the inverted V16
OHC 2V Chrysler Hemi of 36 litres, another oversquare design, which with the usual
USAAF altitude-compensation turbocharger set-up was good for 2,500 hp (& a 'normal'
rating of 2,150 hp) so, about midway between the Griffon & Sabre, (albeit very long).

Of course, Chrysler Corp had to shelve any production plans, due to having the urgent
& highest priority role in sorting out the big Wright radial needed for the B-29 program.

[Tommy Cookers]

https://www.t6harvard.com/
try these (pilot info section) ...
6 avoiding ground loops
2 Harvard landings
5 flying the AT6
1 spinning the T6
etc etc

eg there's photos and even priceless video of a 'ground loop' aka 'swing'
this being due to the inherent mechanical instability of tailwheel aircraft on the ground
maybe now some people won't so quickly dismiss what I write

the ground looping Red Bull D-FGHK seems to be the 800 hp 'German Harvard' but .. nothing on getting that 800 hp
(P&W once catalogued a 720 hp version but it wasn't taken up - though their usual 600 hp was from 73 Octane fuel)
of course all (SC models) were manually throttled eg to 36" or 38" at sea level so could be flown over this boost
unlike the C models - these had charge impellers but behaved as if NA (as did some Kinners eg Harrison Ford's)
no helicopter 1340s had more than the 600 hp
I used to see Denny Sherman's 1200 hp 1820 'Super-Harvard' - we were told not to ask about flying in it

somewhere in the above source it's clearly stated that the T6 is in some ways more difficult than eg a Mustang fighter
eg because it can easily swing either way and correcting a swing can produce a swing in the opposite direction

display Harvards (eg Numan's) probably have a big or/and 3-blade prop ....
Harvard (not SNJ ?) prop sizes seemed smaller than 11' 2" iirc Gunston says pre RAF's reduction (for noise or what ?)
but a small prop better reproduced the thrust/speed characteristic of the trainee's destination aircraft ?


re the supposed prop torque on rapidly increasing power strongly rolling such planes ......
nowhere in flying manuals does it ever tell anyone to apply aileron (roll control) in this situation .... presumably ....
because power increase produces yaw then in the same sense some resulting roll tendency .... whereas ....
applyied anticipatory roll input would be in opposite sense to the yaw - this (a step towards a spin) is to be avoided

re the supposed deficiency of the narrow undercarriage aka landing gear ....
doesn't it allow 'wing-down' crosswind methods that a wide u/c wouldn't ?

[Rodak]

I haven't read the whole thread, so please excuse me if this plane has been mentioned... What about the Martin-Baker MB-5?

https://hushkit.net/2019/01/02/almost-t ... baker-mb5/

https://www.youtube.com/watch?v=bMdv7UBdWw4

[Tommy Cookers]

.... What about the Martin-Baker MB-5?
https://hushkit.net/2019/01/02/almost-t ... baker-mb5/

that hushkit seems to be a brilliant site - well found !

(at the start of this thread I suggested the MB-5 was the Lotus 49 of planes - and the T*****t was the BRM H-16)
the article (by Dr R V Smith C Eng FRAeS) suggests that if the MB-5 had used it ....
the Hawker aerofoil (as Tempest etc) would have reduced high-speed drag and increased critical Mach number ....
but evidence for these benefits seems non-existent
this aerofoil seems to have been hurriedly chosen c. May 1940 (when the Mustang was the hot topic)
to this day no-one seems to know anything about this process and its results (unless maybe Dr Smith does ?)

low wing drag coefficient at lift coefficients close to zero is rather self-defeating as in that case .....
the big drag source isn't the wing
drag was rather useful in ground attack (so enabling many Typhoons to do vertical-dive rocket attacks on tanks)

in critical Mach number all aerofoils classed (or assumed) as 'laminar flow' gave real-world inferior outcomes ie .....
P-51, P-63, Spiteful, Attacker(jet), Tempest, Fury/S.Fury all had wing critical Mach numbers inferior to the Spitfire's according to Morien Morgan the RAE director - who had done much of RAE's Mach test programme
(yes the Spitfire's wing was somewhat 'thinner' - that was the point of its designer's design choice)
https://www.aerosociety.com/media/4855/ ... ective.pdf
on page 17 seems to support this - eg at the same thickness as the Spit wing the e1240 foil had earlier drag rise

NASA technical histories once seemed to claim that the NACA LF foils gave better critical Mach numbers but now ....
seem to have removed those claims (and the bigger claim of much lower drag at low lift coefficients) .....
(this all shown via the link I gave here some months ago)

[J.A.W.]

I haven't read the whole thread, so please excuse me if this plane has been mentioned... What about the Martin-Baker MB-5?

https://hushkit.net/2019/01/02/almost-t ... baker-mb5/

https://www.youtube.com/watch?v=bMdv7UBdWw4

Here's a typically well presented/researched article on the MB-5 written by Bill Pearce:

https://oldmachinepress.com/2017/06/20/ ... 5-fighter/


The MB-5 - unlike its late WWII era R/R Griffon-powered contemporaries (Spiteful/CA-15/Fury)
lacked the by then fashionable - 'laminar flow' - wing, & failed to demonstrate any notable
performance advantages over them, (not that the RAF/RAAF wanted them, either), so there
was zero prospect of a production order, (MB then most usefully turned their hand to ejector
seats when the new-fangled turbo-jet 'Meatbox' fighters started killing its own pilots, relentlessly).

[J.A.W.]

...(at the start of this thread I suggested the MB-5 was the Lotus 49 of planes - and the T*****t was the BRM H-16)
the article (by Dr R V Smith C Eng FRAeS) suggests that if the MB-5 had used it ....
the Hawker aerofoil (as Tempest etc) would have reduced high-speed drag and increased critical Mach number ....
but evidence for these benefits seems non-existent
this aerofoil seems to have been hurriedly chosen c. May 1940 (when the Mustang was the hot topic)
to this day no-one seems to know anything about this process and its results (unless maybe Dr Smith does ?)

low wing drag coefficient at lift coefficients close to zero is rather self-defeating as in that case .....
the big drag source isn't the wing
drag was rather useful in ground attack (so enabling many Typhoons to do vertical-dive rocket attacks on tanks)

in critical Mach number all aerofoils classed (or assumed) as 'laminar flow' gave real-world inferior outcomes ie .....
P-51, P-63, Spiteful, Attacker(jet), Tempest, Fury/S.Fury all had wing critical Mach numbers inferior to the Spitfire's according to Morien Morgan the RAE director - who had done much of RAE's Mach test programme
(yes the Spitfire's wing was somewhat 'thinner' - that was the point of its designer's design choice)
https://www.aerosociety.com/media/4855/ ... ective.pdf
on page 17 seems to support this - eg at the same thickness as the Spit wing the e1240 foil had earlier drag rise

NASA technical histories once seemed to claim that the NACA LF foils gave better critical Mach numbers but now ....
seem to have removed those claims (and the bigger claim of much lower drag at low lift coefficients) .....
(this all shown via the link I gave here some months ago)

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."

[Tommy Cookers]

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)

https://en.wikipedia.org/wiki/Airfoil (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 ..
I think