M.B-5

17 hours ago, Meplat said:

 

 

 

A blown/"Malcom Hood" would have contributed jack and/or shit to the performance/effectiveness of the P-38.

 

 

 Yet they sure did prove useful for the F4U & P-51 et al...

Lockheed didn't use the P-38's multi-framed canopy on their next fighter, the P-80, did they.

The USAAF deemed the P-38 as effectively passe`, & rather than 'polish the turd' - ordered the P-82, instead.

In fact, the USAAF had major concerns about the P-38's shortcomings as a fighter, in the intense combat ETO.

Summarized as:

"...airspeed limitations are low... ...tail buffeting... ...cause structural failure...

...definitely objectionable & hazardous.."

See full report here: http://www.wwiiaircraftperformance.org/p-38/p-38-67869.html

5 hours ago, Meplat said:

Take this for what you will, but you really are coming across as someone who has never seen the inside of the mills in question.

You are getting a simpler looking top end, at the expense of a more complex cylinder, and a much more complex set of valve timing gears.

 

Are you really going to claim that the sleeve valve radial "is better" because you don't like how busy the top end of most radial engine look?

Please. That is patently ridiculous.

 

No.

Even as a kid, I was amazed to see the internal workings of the Hercules,

& again, to conflate multiplicity with complexity - is technically incorrect.

Please refer to Roy Fedden's list of patently revealed sleeve-valve merits, Meplat - to gain a "better" appraisal,

(as linked in the article below).

http://www.flightglobal.com/pdfarchive/view/1941/1941 - 2830.html

Meplat, with no moving parts above the piston, & many fewer parts overall than a poppet valve mill,

the sleeve valve is indeed quite "straightforward" by comparison,

& on the record, Kiwi Bristol mech/techs got 3,000hr TBOs from their Hercs..

Yeah fair enough, boss - can/will do.

2 minutes ago, Sturgeon said:

 

Not really. This, as you might have noticed by the name, is my house.

Ok "D.J.T.", so you hold the ah, 'trump cards', I geddit,

& aint no sorry sucka caint beat the house, just like in Vegas...

13 minutes ago, Meplat said:

And now you're whistling through the graveyard.

I worked on P&W and Wright radials that had been run hard for 50+ years. 

Much as I liked the tech of the Sabre, it is a museum piece, while the 2800 is still converting 100LL into "go", and likely will be for a while to come.

 

 

The thread is about WW2, era machines though, right?

However Kermit Weeks is in the process of restoring his super-rare Sabre-Tempest to fly,

& has a couple of NOS Sabres - on hand for it.

Mike Nixon reckons the Sabre is less complex than popularly supposed,

being more a case of multiplicity of parts, & is a "straightforward" engine to overhaul.

29 minutes ago, Meplat said:

It's around 2 quarts/hour barring WEP/MAX op.

J_G_T's kindly posted figures for the F4U's R-2800 - gives a max cruise oil consumption of 16 Qt/hr!

4 minutes ago, Meplat said:

Great, and by then it was thoroughly obsolete for fighter use. You are not going to stuff a late Sabre in an airliner when you can do the same work, more reliably, with a 2800 or a Herc.

 

 

 

 

 

Actually, the RAF flew their Sabres, & flew them hard* - for 10 years post-war, so they can't have been all that bad...

* At power levels that would make an R-2800 wilt, from heat-soak, & need a lie down.

9 minutes ago, Sturgeon said:

 

???

 

I am asking you to follow the forum guidelines. Did you read them?

 

You've got to build a rapport with people before you go around nitpicking their shit. This is basic human interaction 101 stuff.

That door swings both ways, does it not?

I was responding to his querying my apparent misapprehension - as it happens.

& do the 'guidelines' include a basic standard of language usage requirement?

The final Sabre made 3,500hp for take-off - from 2238 CI, somewhat better than the R-2800's 1 per..

Here are the Bristol Hercules consumption figures, they are fairly good, Meplat - can you post those for the R-2800?

http://www.flightglobal.com/pdfarchive/view/1946/1946 - 2242.html

Huh?  Oh, I geddit, 'haze the newbie'... aww c'mon, jeeze...

Anyhow... this period 'Flight' article shows how the liquid-cooled engine still offered a superior installed power-to-weight ratio.

( Sabre versus R-2800).

http://www.flightglobal.com/pdfarchive/view/1946/1946 - 1443.html

1 hour ago, Collimatrix said:

 

 

Whoah whoah whoah.

The critical mach number problem was mainly an issue of sonic shock waves forming over the wings of the aircraft.  All wings will do this if the airflow over them gets fast enough, the problem was just that most airfoils designed in the 1930s would form shock waves at fairly low mach numbers.  The reason that the Tempest out-dives a Lightning is that it has laminar flow wings, not that it has a single engine.  Laminar flow wings have a higher critical mach number than the traditional airfoil designs that were used in the late 1930s.

Very few Axis fighters had laminar flow wings, the J2M Raiden being the only one I can think of offhand.  The Bf 109, being a mid 1930s legacy design definitely started with traditional airfoils, and I can find no reference to the Bf 109 having ever been re-designed to have laminar flow wings.  Likewise, the FW-190 seems to have lacked laminar flow wings as well.  So the Bf 109 and FW-190 would also have problems with their critical mach numbers while diving, and most likely at around the same airspeeds as the P-38.  If their airfoils were slightly less cambered or had a slightly higher chord to thickness ratio then M_crit may have been somewhat higher, but it would have been a small difference of degree rather than kind.

No, the 109/190 readily exceeded the P-38's Vne in the dive, & like the P-51, didn't need 'dive flaps' to regain control.

The thick-winged Typhoon was still cleared to dive at a 525mph EAS limit, though the Tempest's 'high speed wing ' profile allowed a later onset of drag/extra control capability & gave another ~25mph advantage - across the flight regime , by comparison.

P-38 'buffet' - bad enough to cause structural damage - was noted by the USAAF as a fundamental problem.

The Tempest was very robust though, with an ultimate stress rating of 14G, rather more than the USAAF design max.

See: period drag/structure documents; http://www.ww2aircraft.net/forum/threads/structure-weight-data-and-drag-analysis.42716

On ‎15‎/‎11‎/‎2017 at 1:14 AM, Jeeps_Guns_Tanks said:

Don't forget the wonderful for making the plane handle poorly so it was drained before the drop tanks behind the pilot fuel tank in the P-51D.

"...drop tanks behind the pilot..."

Yeah, sorry to be a grammar Nazi, J_G_T, but that's a real lousy sentence.

& sleeve-valve engine oil-consumption was certainly better than the big US radials, with their loose clearances

plus a multitude - of leaky joints...

The P-51 was not only much more fuel efficient/aero-slick than the R-2800 powered gas-hogs,

_ its cruise speed was ~ 100mph faster.

Funny that both the P-51 & P-47 were deemed worthy of significant revision (despite being in high demand),

but the P-38 wasn't, - due to the Lockheed being fairly close to being past its 'best by date' - by USAAF appraisal/reckoning.

& the German forces were a far more effective/dangerous enemy than those of Hirohito,

just as the USAAF losses lists - clearly show.

Have you sat in a P-38?

There are canopy frames which intrude on a clear view, & they're lateral-wise, right at eye-level,

annoyances which are notably absent from a proper,  blown 1-piece - bubble canopy.

P-38 missed out on a bubble canopy upgrade, unlike the P-47, & P-51.

P-47D got an improved windshield & bubble canopy - which was pretty much a straight copy

- from the Hawker Typhoon.

When the 'Mighty 8th' cast-off its P-38 & P-47 units for the more effective P-51, the 9th 'tactical' AF got them,

for 'mud-moving' tasks, even though they were expensively optimised for high-altitude work with turbochargers,

& not at their best - down low. 

The 9th AF quickly found the P-38 to be too big, & too vulnerable/costly to use in the A2G role,

( as were the A-20/A-24/A-26 in the ETO) & so then tried them as defacto medium bombers

( Mosquito style) instead, but they weren't too effective in this, either.

The 9th AF P-47s suffered fairly heavily in their new tactical duties on ground support for the invasion forces,

losing nearly 1500 in combat between D-day & VE-day, both to flak & Luftwaffe anti-JaBo ops,

which proved more profitable for the Jagdwaffe, than vainly trying to battle the P-51s.

Ironically, the P-51's outright victory figures ( & victoty-to-loss ratios)  for both A2A, & A2G ops

- were better than the putatively 'rugged' P-47, let alone the pretty-much unwanted P-38.

Both 109/190 could lose the low Mach/high drag handicapped P-38 in a dive, as well as being able to contend effectively in A2A combat  with the fat-as P-47 below 15,000ft, (esp' when the 'Jug' was bomb-laden,

& even a forced ordnance jettison - was rated a 'success' for the hard-pressed LW fighters).

The P-38's low limiting dive-speed of ~440mph EAS was poor versus the single-engines fighters in the ETO,

(  ~100mph less - than some, such as the Tempest).

Cheers, LC. 

You may find some data of interest in this table here too;

http://www.flightglobal.com/pdfarchive/view/1947/1947 - 1491.html

Note also the fuel efficiency of the sleeve-valve Napier Sabre V, 56.7 gallons per hour making 890hp/2500rpm,

versus the R-R Merlin 500 @ 71.5 gph for 90 hp more at 2650rpm  - while needing another +6.5lb of forced induction boost.

For comparison, an earlier Napier, an unsupercharged sea-level DOHC 4V W12 Lion race engine on 10:1 comp ratio made 880hp @ 50 gph.

http://www.flightglobal.com/pdfarchive/view/1945/1945 - 1118.html

Hey Surgeon, I can get how "fresh meat" would be your thing,

- it sure beats hacking on stinkin' ol' corruption-raddled gangrenous rot...

But - if facts can intrude on the niceties fo' a mo', then fo' sure, we can straighten some sheets..

You want WW2 piston-power for fighter take-off, forget about a lazy-bones radial, check this intense machine out...

http://www.flightglobal.com/pdfarchive/view/1945/1945 - 2284.html

&, liquid-cooling allowed that "climbing" power rating to be enabled for an hour, something an air-cooled engine aint doin'

Hi y'all.

Some interesting views put forth, here in this thread.

Do allow some corrections, though, won't you fellas...

1,The rear "Aux" fuselage tank in the P-51 wasn't actually a "drop tank" - it was for transit flying & was used 1st,

rather than in combat.

2, P-38 did ok against the lesser forces of Nippon, but could not technologically* hack the pace in the ETO,

  & was replaced by the P-51.

3, P-47, like the other P&W R-2800 powered fighters  - was a real gas-hog,  even at a slow cruise speed,

& like the P-38, was dumped by the 8th AF, on the advent of the P-51 - arriving in numbers.

4, P-51 did not need the "dive flaps" belatedly attached to both P-38 & P-47 to recover control,

& pull out safely - from 'Mach crit' high speed dives.

5, Victory stats collected by the USAAF in the ETO, confirmed their top choice of the P-51 as air-superiority fighter,

- was the right one**.

* P-38 was a real handful of control complexity to simply fly, let alone operate in combat - esp' against the faster diving 109/190, whose pilots could spot the big twin-boom Lockheed from a distance,

& then choose an attack profile - to suit themselves. 

**The RAF wanted all the Mustangs they could get, (even the Allison powered ones, which they used 'til war's end),

but didn't want P-38's, & relegated the hundreds of lend-lease P-47's they received - solely to combat against the lesser forces of Nippon, too.