Thoughts on the Current Flight Model

[Sable]

Wow, it's nice to see others have developed an interest in this subject.  MW and Neil really have unconvered a treasure trove of data, all of which supports the idea that all of the 8th AF FC groups switched to 150 octane, raised their boost levels, and continued to operate in this manor until V-E Day.

Originally posted by Charge
It seems that there is no document showing how wide spread the boost increase was in USAAF. Benny claims that the conversion was easy- all right, but to what extent were they completed and when?

While there isn't any one document that specifically describes the boost modifications carried out by each unit, keep in mind that nearly every mention of supplying 150 octane fuel to the 8th AF, right from the start, also mentions the performance increase that the fighters will get from it, and in some cases the increased boost levels that will be used to achieve this.  It's pretty clear that everyone understood the goal of supplying 150 octane fuel was to raise boost levels on the aircraft.  It's also clear that in the USAAF in the ETO, only the 8th FC ever used 150 octane (there are a couple of quotes floating out there talking about Mustangs at Iwo Jima using higher octane and higher boost, but I've never seen anything else on that).

There are documents stating that 150 octane fuel was supplied to and used by every 8th AF Fighter Command unit, and that it replaced the old 100/130 octane.  There are documents stating what the new approved boost levels were with 150 octane fuel.  There is a document describing the procurement of conversion kits for 8th AF fighter aircraft to allow the higher boost levels.  There is a document describing how all the replacement fighter aircraft being processed by the 8th AF were being modified to use 150 octane.  There are documents from the 78th and 359th fighter groups describing modifying their aircraft.  And there are statements from pilots of the 20th, 353rd, 357th, 361st, 364th, and 479th fighter groups describing the use of 70" or more manifold pressure (all of these were in Mustangs).   There are also pictures of 78th, 353rd and 357th FG aircraft remarked for 150 octane (and you would generally think that if the crews took time to repaint the placard, they would probably make the necessary boost mods as well), and a picture of a 352nd FG P-51 being fueled from a truck marked 150 octane.

All of that can be found on MW and Neil's web site.  Here is a breakdown of the 8th AF's fighter units, what they were flying in June of '44 when 150 octane fuel came on the scene, and when they converted to other aircraft:

4th FG: P-51 from June 44 to May 45
20th FG: P-38 until July  44 - converted to P-51
55th FG: P-38 until July 44 - converted to P-51
56th FG: P-47 from June 44 to May 45
78th FG: P-47 until Dec 44 - converted to P-51
339th FG: P-51 from June 44 to May 45
352nd FG: P-51 from June 44 to May 45
353rd FG: P-47 until Oct 44 - converted to P-51
355th FG: P-51 from June 44 to May 45
356th FG: P-47 until Nov 44 - converted to P-51
357th FG: P-51 from June 44 to May 45
359th FG: P-51 from June 44 to May 45
361st FG: P-51 from June 44 to May 45
364th FG: P-38 until July 44 - converted to P-51
479th FG: P-38 until Sept 44 - converted to P-51

So we can see that of the 4 P-38 FGs in June, 3 groups used the 150 octane and higher boost settings for about a month, and 1 group for about 3 months.

The P-47s enjoyed a longer run with high boost.  Of the 4 P-47 FGs in June, 1 used the 150 octane for about 4 months, 1 for about 5 months, 1 for about 6 months, and 1 until VE day.

The P-51s got the most benefit, with 7 fighter groups using 150 for the entire period, and all but one of the remaining groups converting to P-51s within the next 6 months.

For those not familiar with USAAF organization, a group would typically put up about 50 aircraft on one mission (generally 3 squadrons of 16 plus a few spares).  Doing the math, this means that 8th FC could (and often did) put up 700 or more high boost Mustangs on a single mission, and for shorter periods of time at their peaks, 200 + high boost P-47s or 200 + high boost P-38s.  Obviously the 47's and 38's weren't super common in this configuartion.  

But consider that only around 400 N1K2s were ever built at all (taken from Francillon), or that in early 1945 only 398 La-7s were in frontline units and only 291 of those were combat ready (from Gordon & Khazanov), or that on the 31st Jan 45 the Luftwaffe only had 314 109K-4s available in it's frontline units (from Kurfurst's site).  Or consider some of the extremely rare perk planes like the Ar234, Me163, Me262, Ta152 etc.

[Knegel]

Hi Widewing,

why the Temp with more weight climb better in your graph(blue/red line)??
What boost the Temp did use below 5k to archive the displayed climb down there??

I didnt know there was something called "fighter conference", if you have the Vaught docus, you should have known to which comparison i was refering to.

Anyway, the P38J and P51B was absolut common fighters till the end of war and absolut not outdated in oct.44. According to Bennys guess the usage of a higher presure as WEP was common in October 44 also for the P38J, since it seems that also the new P38L only got tested with a WEP of 60", while the P47D got its 2600HP i only can guess that at this time the 66" or higher boost dont got widely used in P38īs.

For now i only did read about the few recon P38Līs in Europe, using the higher boost, similar to the V1 intercepting planes.


Benny,

i still dont saw a proof that Kurfi did lie. He was probably wrong, when he thought Big Kahuna(is this the Big Kahuna who former did play EAW??) lie to O M, but that dont make him to a liar.  A liar know that he is wrong,  while Kurfi simply tend to overreact when he start to discuss. His fault was to assume that Big Kahuna lie and of course to speak this out loud, and even more bad this get, when this assumtion get proven as wrong. I absolutly agree to you here, but thats actually what you do as well!!

You only assume that Kurfi did lie!! You could call him deaf for oposide arguments, or badly biased due to a selective blindness, wishfull thinking, not nice(i bet he play rockīn roll), to have bad manners,  constandly overreacting etc, thats the normal behaviour of many enthusiasts/fanatics, including you, but all this isnt a lie and this dont make the datas on his page or his page bad in general!!

He got banned for his behaviour from this board, to use the same bad manner to try to devaluate his page by calling him a liar simply is like to throw the helve after the hatchet.
Actually i only was up to inform you that your reputation dont get better by using the same manner, like Kurfi, and same like Kurfis behaviour is contraproductive for the 109 datas, also your behaviour make Kurfi rather more credible, cause most "normal" people simply tend to be mistrustful regarding fanatics and extreme enthusiasts, but of course its up to you.


Greetings,

Knegel

[Knegel]

Hi Sable,

the question is to what boost the P38 and P51 could(was allowed to) use with 150 octane fule on their long range missions?

Since two US fighter comparisions from okt.44 show the P38 with only 60" and the P51īs with only 67" heading, while the P47D and F4U-4 got the higher boost,  i only can guess there was a good reason for this.

At least it dont realy make sence to me that there are two different fighter comparisons, where "downrated" and "uprated" planes get compared, while, accorsing to your post, the "downrated" planes should have been uprated at least 6 moth before this comparisons was made.


Greetings,

Knegel

[Widewing]

Originally posted by Knegel
Hi Widewing,

why the Temp with more weight climb better in your graph(blue/red line)??
What boost the Temp did use below 5k to archive the displayed climb down there??

I didnt know there was something called "fighter conference", if you have the Vaught docus, you should have known to which comparison i was refering to.

Anyway, the P38J and P51B was absolut common fighters till the end of war and absolut not outdated in oct.44. According to Bennys guess the usage of a higher presure as WEP was common in October 44 also for the P38J, since it seems that also the new P38L only got tested with a WEP of 60", while the P47D got its 2600HP i only can guess that at this time the 66" or higher boost dont got widely used in P38īs.

For now i only did read about the few recon P38Līs in Europe, using the higher boost, similar to the V1 intercepting planes.

When looking at the modified chart, the black line represents the third production Tempest Mk.V as tested by the AFDU. It shows both MIL power and Combat power climb at 9 lb boost. The Blue line represents the AH2 Tempest climbing at full load and 10.5 lb boost. Also plotted is the AH2 Tempest climbing at 25% fuel and 10.5 lb boost.

Now, here's where it gets interesting. If the AH2 Tempest is fitted with the Sabre IIA, it would be cleared for 10.5 lb boost only if using 150 octane fuel. If it is fitted with the Sabre IIB, it should pull 12.0 lb of boost. So, depending upon which engine was modeled, the AH2 Tempest is either too slow or too fast.

What we may have is an amalgam of the Sabre IIA and Sabre IIB, as the AH2 Tempest fits right in between the two.

Max Sea Level Speed for Tempest powered by:
Sabre IIA: 378 mph (9 lb boost)
Sabre IIB: 394 mph (12 lb boost)
AH2 Tempest: 388 mph (10.5 lb boost)

This makes sense to me, and I can see why HTC would model it that way.

As to the Vought data, I didn't recognize what you were referring to until you posted the actual pages.

By October of 1944, there were few, if any P-51Bs in combat service in the ETO or MTO. Most had been retired as War Weary by then. The same thing applies to the P-38J. Most, if not all had been replaced by the P-38L, and none were flying with the 8th AF by October. By then, all P-38 groups had transitioned to the P-51, with their remaining servicable P-38s being transferred to the 9th or 15th Air Forces.

My regards,

Widewing

[mw]

Hello Widewing:

The Tempest V with Sabre IIA was operated at +9 or +11 lbs/sq.in. 3700 rpm
The Tempest V with Sabre IIB was operated at +11 of +13 lbs/ sq.in. and 3850 rpm

Tempest V with Sabre IIB


Pierre Clostermann (Free French) wrote of the Tempest:

   "Nothing was left undone to give the Tempest a maximum performance at medium and low altitudes. Special auxiliary tanks were designed even, with perspex connecting pipes, to fit under the wings. Quite extraordinary attention was paid to the rivetting, the joints and the surface polish. The result was a superb combat machine.
    It had a thoroughbred look and, in spite of the big radiator which gave it an angry and wilful appearance, it was astonishingly slender. It was very heavy, all of seven tons. Thanks to its 2,400 h.p. engine it had a considerable margin of excess power and its acceleration was phenomenal. It was pretty tricky to fly, but its performance more than made up for it: at 3,000 feet, at economical cruising on one third power (950 h.p.) with two 45-gallon auxiliary tanks, 310 m.p.h. on the clock, i.e. a true air speed of 320 m.p.h.; at fast cruising speed, at half power (1,425 h.p.) without auxiliary tanks, 350 m.p.h. on the clock, i.e. a true air speed of nearly 400 m.p.h.; Maximum speed straight and level with + 13 boost and 3,850 revs.: 430 m.p.h. on the clock, i.e. a true airspeed of 440 m.p.h.
    In emergencies you could over-boost it up to nearly 3,000 h.p. and 4,000 revs., and the speed went up to 460 m.p.h. In a dive the Tempest was the only aircraft to reach, without interfering with its handling qualities to any marked extent, subsonic speeds, i.e. 550-600 m.p.h."

Sable: nice I was going to post some thoughts here on the Mustang, but I think that deserves its own thread and I don't want to get off the main topic widewing is discussing.

Mike

[Knegel]

Hi Widewing,

so this is wrong??

"Most of the P-51B/Cs were assigned to the 8th and 9th Air Forces in England, with a lesser number with the 12th and 15th USAAF in Italy. The P-51B/C remained the prime Mustang variant in service from December 1943 until March of 1944, when the bubble-topped P-51D began to arrive. However, P-51B/C fighters remained predominant until the middle of 1944, and remained in combat until the end of the war in Europe even after the arrival of large numbers of P-51Ds. Even as late as the last month of the war, 1000 out of the 2500 Mustangs serving in the ETO were of the P-51B/C variety"

From this page, which i always thought to be a good one:
http://home.att.net/~jbaugher1/p51_8.html

(I know the late P51B/Cīs got the newer engine anyway)


Whats about the climb of the Temp in low level, shouldnt be the Vmax at very low level also much better and in 3-5000ft??

Greetings,

Knegel

[EagleDNY]

Originally posted by Kev367th
Is it an order though, or a document of what they would like to do?

Even he states it is proposed changes.

Given that the LW was having to re-assign non essential fuel (including training and testing) to frontline units to come close to keeping sorties close to consistent from Jan 45 onwards, where does the extra C3 needed for 1.98ata come from, considering the 190s had to have it.

Or does it make more sense to leave things as they are, were the K-4's can use B4 or C3.

Should add also - did the ever get the plugs required for 1.98ata?

My main gripe - He said it took the RAF some 2 months from a clearence or order for a mod for it to start happening (look at the Spit I boost thread), yet quite happily asserts that in Germany 2 months from the end of the war some 76 K-4's were converted in those 2 months.
Funny how double standards crop up time and time again.

Agreed - I don't see any way to prove how many, or if 109 units got the 1.98ata boost.

Back on the original topic though - I tested the AH 109K at altitude vs some lookups I did on 109K performance, and they appear to be pretty close.  The 109K at 24,600ft was doing 429 MIL / 445 WEP, which is about 5mph faster than my Janes has listed.  

Weight of Ammo seems to make no difference to max speed - I managed to get the same 445mph loaded with ammo, and empty.  

EagleDNY
$.02

[Widewing]

Originally posted by Knegel
Hi Widewing,

so this is wrong??

"Most of the P-51B/Cs were assigned to the 8th and 9th Air Forces in England, with a lesser number with the 12th and 15th USAAF in Italy. The P-51B/C remained the prime Mustang variant in service from December 1943 until March of 1944, when the bubble-topped P-51D began to arrive. However, P-51B/C fighters remained predominant until the middle of 1944, and remained in combat until the end of the war in Europe even after the arrival of large numbers of P-51Ds. Even as late as the last month of the war, 1000 out of the 2500 Mustangs serving in the ETO were of the P-51B/C variety"

From this page, which i always thought to be a good one:
http://home.att.net/~jbaugher1/p51_8.html

Yes, Baugher is incorrect. He is also contradicts himself by stating further in his article that, "Some 3740 P-51Bs and Cs were built. Some of the served with front-line units until the end of hostilities, but others were converted as two-seat trainers or squadron hacks."

Did you look at Baugher's sources? Generally pulp aviation books of dubious value. Baugher writes general histories based on what he has gleaned from standard pulp aviation titles, which are generally unreliable.

The number of Mustangs in the ETO was considerably less than 2,500. As of March 28 1945, 1,715 P-51s were in service with the 8th and 9th Air Forces (AAF Statistical Charts), as well as 1,974 P-47s and 249 P-38s. In the MTO we find 532 P-51s, 383 P-38s and 361 P-47s.

So, the grand total of P-51s service in both the ETO and MTO was 2,247 with about 5 weeks to the surrender. With P-51Ds and P-51Ks still arriving in great numbers, the number of P-51B/C fighters remaining would only shrink more by the war's end.

As of the end of March, 1944, the Luftwaffe was facing well over 5,000 American fighters as well as the fighter arm of the RAF and a considerable number of Soviet fighters. The total (not counting Free French or Italians) probably exceeds 10,000 fighters.

The best sources are Group and Squadron records. By October 1944, there were probably less than 100 P-51B/C aircraft still on combat duty with the 8th AF. Even the 9th AF was replacing its worn-out P-51B/C types with P-47s (virtually all P-51Ds were being allocated to the 8th and 15th Air Forces at that time). By D-Day, the majority of P-51s in many 8th Groups were P-51Ds. You see this in photos of this time period. Fast forward to January of 1945 and you don't see any P-51B/C fighters in photos.

Many of the last P-51B/Cs to roll off the line were sent to the CBI (early June of '44) to replace worn-out P-51A and P-40 types. All P-51B production ceased in early March of 1944, with the line being switched to the D model. Hundreds of P-51D-1 and P-51D-5 fighters were deactivated for being war weary, and assigned as hacks or used by the various Group's Clobber College combat training commands. Many were simply scrapped for spare parts.

One thing that kept many of the later P-51B/C fighters in service in the ETO and MTO was the delay of delivery of P-51Ks. The K model was fitted with an Aeroproducts prop and there were vibration issues associated with the propeller. This slowed delivery to a trickle. The first P-51Ks arrived in the ETO in September or 1944, replacing the older B and C models still soldiering on in combat squadrons.

I am not aware of a single P-51B/C still in combat service with the 8th AF when the war ended. There may have been some, but they do not show up on any of the Group end-of-war inventories that I have seen. There could not have been very many serving with the 9th and 15th Air Forces either.

My regards,

Widewing

[Knegel]

Hi Widewing,

thanks for this infos, thats very informative(like usual)!!

But anyway, although the P38J and P51B/C wasnt in production anymore, they was still in usage in probably not that smal numbers in oct.44.
What you call MTO was already rather ETO in oct.44, although it was the south front(german point of view) and the P51D in the other comparison also got tested with only 67", so the main argument stay valit anyway.

Afaik the P38L dont saw service in fighter units over europe, is this information also wrong??

Greetings,

Knegel

[Benny Moore]

Yes, it's wrong.  The P-38L saw very much combat over Europe, and it did run at 70+ inches.

[Widewing]

Originally posted by Benny Moore
Yes, it's wrong.  The P-38L saw very much combat over Europe, and it did run at 70+ inches.

But, only those P-38s serving in the 8th AF were running the high boost. The 9th AF and 15th AF were not issued 150 octane avgas (at least to my understanding). If they were running at higher than normal boost it was because the engines and regulators had been rigged for the full Allison rating of 1,725 hp courtesy of the Allison tech reps.

P-38 groups in the MTO were largely equipped with P-38L-1 and P-38L-5 aircraft. Well over 300 of them. P-38 Groups in the ETO (9th AF) were also flying P-38Ls. Again, well over 300 were in service there too.

My regards,

Widewing

[Benny Moore]

That sounds right.  I was addressing Knegel's statements, "It seems that also the new P38L only got tested with a WEP of 60" and "P38L dont saw service in fighter units over europe."

[Knegel]

Hi Benny,

if you quote me, could you do that right please??

It was a question by me, not a statement!!

And the question remain, when and how often it did run on 70"!!

At least it dont seems to have been before oct.44, cause a fighter comparison only make sence when the common powersettings get used, not the older derated versions.

Afaik the P38īs had bad trouble in higher alt with the normal boost and fuel, maybe the 150 octan fuel made them only able to use 60" WEP without to fear dead engines up there?

Hi Widewing,

its realy interesting and scary to see how much datas in books vary from obvious historical base sources.

So the P38L took place in Europe as fighter not only as recon plane! Good to know, thanks!

Greetings,

Knegel

[Old Sport]

Originally posted by Knegel
So the P38L took place in Europe as fighter not only as recon plane!

Captain Hallberg



Best Regards

[Bronk]

Originally posted by Knegel
Hi Benny,

if you quote me, could you do that right please??

It was a question by me, not a statement!!

And the question remain, when and how often it did run on 70"!!

At least it dont seems to have been before oct.44, cause a fighter comparison only make sence when the common powersettings get used, not the older derated versions.

Afaik the P38īs had bad trouble in higher alt with the normal boost and fuel, maybe the 150 octan fuel made them only able to use 60" WEP without to fear dead engines up there?

Hi Widewing,

its realy interesting and scary to see how much datas in books vary from obvious historical base sources.

So the P38L took place in Europe as fighter not only as recon plane! Good to know, thanks!

Greetings,

Knegel

Knegel
Well as far as I know the earlier 38s had problems at high alt due to over cooling.  Start an older carbed auto with a stuck open choke. Then floor it while it is still cold, you will in effect shut off the engine. That was happening to the early 38s.

The latter models (if I remember right), fixed this or found a work around.

Bronk