Tempest Mark V research

[Talon_]

Sabre IIB modification ?

 

 

More evidence of Sabre IIB at +13lbs with Rotol props

Edited August 22, 2018 by Talon_

[Talisman]

Kurfurst,

 

Did you not read the squadron operations record book extract I posted above? 

It clearly shows 56 Sqn on anti-diver patrols on the 5th September and then operating over Europe the very next day on the 6th September.  This records what actually happened. 

On other threads that have also involved you, so I presume you read them, I have posted Spitfire operations record books that also show anti diver sorties carried out by a squadron, followed by routine non anti-diver operations, sometimes on the same or next day!

What you have just posted records a decision taken at a point in time, but not what actually happened in the end.  You have not shown that the decision was followed through! 

The squadron operations record books show what actually happened.  

On the other hand, you keep posting about intentions and decisions that were not followed through. 

 

Happy landings,

 

Talisman

 

[Kurfurst]

Dear Talisman,

 

The summarize your thesis, your assumption is that the Tempest kept using higher boost sanctioned only for V-1 operations after decision was made to revert to the prior standard rating of +9 boost in the period from mid-September 1944.

 

Given that the burden of proof is on you, I am afraid it is you that needs to support this thesis, however unlikely it is that it can be supported. 

 

Personally I think that the fact that no victories claims were made in the period while Tempest squadrons were authorized to use higher boost in connection with V-1 intercepts is very telling as to the relevance of special boosts between August-September 1944 as far as combat operations are concerned. 

[Talisman]

48 minutes ago, VO101Kurfurst said:

Dear Talisman,

 

The summarize your thesis, your assumption is that the Tempest kept using higher boost sanctioned only for V-1 operations after decision was made to revert to the prior standard rating of +9 boost in the period from mid-September 1944.

 

Given that the burden of proof is on you, I am afraid it is you that needs to support this thesis, however unlikely it is that it can be supported. 

 

Personally I think that the fact that no victories claims were made in the period while Tempest squadrons were authorized to use higher boost in connection with V-1 intercepts is very telling as to the relevance of special boosts between August-September 1944 as far as combat operations are concerned. 

Kurfurst,

 

It would appear that you are not reading squadron operations record books, because they show anti-diver (150 Octane) squadrons of various aircraft types, on operations over Europe.  Anti-diver squadrons were not wasted doing nothing when not on the roster for anti-diver duties, they were also used for other duties.  All anti-diver squadrons were not on anti-diver duty together the whole time.  There was a war on and resources had to be used to maximum effect. 

As for continued use of 150 Octane, continued consumption of 150 Octane points to continued use of 150 Octane.

Finally, please don't attempt to summarize what I say, the actual words written by me should speak for themselves.

 

Happy landings,

 

Talisman

Edited August 22, 2018 by 56RAF_Talisman

[Talon_]

@VO101Kurfurst the burden of proof is currently on you to find any actual documentation of a Sabre II on +9lbs at really any point in our campaign. Pilot accounts, technical reports, books or modification documents. Anything at all really.

 

In fact that letter clearly is a confirmation that+11lbs works fine on 130 grade and that sticking with +9lbs is pointless.

 

Paragraph 2 states the engine is fine on 130 grade, paragraph 3 highlights how unnecessary reverting the boost level is.

 

[Kurfurst]

So we are left with that SHAEF HQ  'decided to revert to the use of 130 Grade Fuel and to adjust engines to their previous maximum boost pressure' on 18 September 1944 and that Talisman is on the opinion that this wasn't carried through.

3 minutes ago, No.41_Glen said:

 

Tempest couldn't shoot down luftwaffe when they couldn't find them in July & August 1944. When Tempest squadron bases moved to the continent?   Tempest,109 and 190 are short ranged aircraft.

 

I believe No. 56 Squadron and No 486 were the first to move to the continent on 28th September 1944. The next day they had made some airial victory claims. Others followed in October.

 

Note that this is ten days after it has been decided to revert to 130 grade and +9 lbs boost, and that the 2nd TAF on the Continent had 130 grade fuel at this time anyways.

[Talon_]

Kurfurst your document is clearly stating that reverting to +9lbs is not necessary on 130 grade. 2nd and 3rd paragraphs. It's a letter of criticism of this idea.

Edited August 22, 2018 by Talon_

[Kurfurst]

3 minutes ago, Talon_ said:

Kurfurst your document is clearly stating that reverting to +9lbs is not necessary on 130 grade. 2nd and 3rd paragraphs. It's a letter of criticism of this idea.

 

'M.A.P. only cleared the engine for +11 lbs. boost operation while the Tempest aircraft were employed against the flying bomb and that it is their intention to reduce the maximum allowable boost pressure to +9 lbs / sq. inch now that the menace is over'

 

Crystal clear, isn't it.

 

Edited August 22, 2018 by VO101Kurfurst

[Talon_]

Yes those are the words, but context is important. In the context of the 2nd paragraph, the 3rd paragraph is clearly stating that M.A.P.'s intention is no longer necessary.

[Kurfurst]

So any evidence that M.A.P. changed their mind.

[MiloMorai]

"... it is their intention to reduce...." is not the same as "shall be reduced" or "will be reduced".

 

Definition of intention for English Language Learners

• : the thing that you plan to do or achieve : an aim or purpose

[Talon_]

Not required as we have consistent accounts on +11lbs and engine modifications to IIB standard with no +9lbs accounts in between.

 

Next you will be asking for evidence of +11lbs on every sortie

Edited August 22, 2018 by Talon_

[Kurfurst]

Care to post some of these 'consistent accounts' for late 1944.

[Talon_]

1 minute ago, VO101Kurfurst said:

Care to post some of these 'consistent accounts' for late 1944.

 

Sorry, perhaps I did not make myself clear.

 

There are no accounts of Tempests on +9lbs after they are cleared for +11lbs on 150 octane (which is later modified to include 130 octane).

 

Your logic suggests I have to find evidence that the boost level was not dropped for every individual day of the war.

[Kurfurst]

Yes indeed you need to present evidence that Tempest kept using +11 after decision was made to reduce boost to +9 lbs on 18th September. 

[MiloMorai]

Just now, VO101Kurfurst said:

Yes indeed you need to present evidence that Tempest kept using +11 after decision was made to reduce boost to +9 lbs on 18th September. 

 

You do have trouble with English don't you. Intending to do something and doing something are not the same.

[Talon_]

3 minutes ago, VO101Kurfurst said:

Yes indeed you need to present evidence that Tempest kept using +11 after decision was made to reduce boost to +9 lbs on 18th September. 

 

You have posted no evidence other than a document recommending against this policy.

[Kurfurst]

So no evidence to your thesis then, Talon.

[MiloMorai]

1 minute ago, VO101Kurfurst said:

So no evidence to your thesis then, Talon.

 

Like you have no evidence that 4  Gruppen used 1.98ata.

[Talon_]

I do not need to prove +11lbs was not removed from active aircraft for every sortie ? you cannot prove that any planes flew on +9lbs after September! All you have is a document that stops the previous plan of de-rating the engines. Your document, which states that the RAF do not think it's necessary to reduce boost on 130 grade fuel, is my evidence.

Edited August 22, 2018 by Talon_

[NZTyphoon]

12 minutes ago, Talon_ said:

 

You have posted no evidence other than a document recommending against this policy.

Here's a document dated January 1945 clearly stating that the Sabre IIB, which was fitted to the majority of operational Tempest Vs in operational service was rated for + 11 lbs only

Edited August 22, 2018 by NZTyphoon

[Talon_]

5 minutes ago, NZTyphoon said:

Here's a document dated January 1945 clearly stating that the Sabre IIB, which was fitted to the majority of operational Tempest Vs in operational service was rated for + 11 lbs only

 

I am arguing for +11lbs.

 

Before Kurfurst jumps on this document, the Sabre IIA is included because it equips a lot of Typhoons.

[Kurfurst]

12 minutes ago, Talon_ said:

Your document, which states that the RAF do not think it's necessary to reduce boost on 130 grade fuel, is my evidence.

 

So the document that states that +11 boost was employed for V-1 intercept purposes only and it is now to be reduced to +9 lbs is supposed to be the your evidence to the exact opposite. 

 

Classic.

[Talon_]

3 minutes ago, VO101Kurfurst said:

 

So the document that states that +11 boost was employed for V-1 intercept purposes only and it is now to be reduced to +9 lbs is supposed to be the your evidence to the exact opposite. 

 

Classic.

 

Kurfurst the second paragraph is a clear and obvious criticism of the third paragraph.

[Kurfurst]

If that is supposed to be your evidence, it is very unconvincing.

[Talon_]

1 minute ago, VO101Kurfurst said:

If that is supposed to be your evidence, it is very unconvincing.

 

Yet you are the only person of about 5 users here who are not convinced.

[Kurfurst]

It must be a coincidence that its always the same 5 users, and they always agree with and perfectly convince each other, even if nobody else. ?

[Talon_]

Because we are able to critically analyse documents and source material without bias.

 

If I am so biased, why did I spend half this thread arguing against spring-tab ailerons? And suggest that Tempests might not feature at all for the early campaign? You would think if I wanted the Tempest in the best possible light I would be trying to cover up the possible removal of the spring tab ailerons.

 

My interest is in history represented as accurately as possible.

[NZTyphoon]

1 minute ago, Talon_ said:

 

I am arguing for +11lbs.

 

Before Kurfurst jumps on this document, the Sabre IIA is included because it equips a lot of Typhoons.

By January '45 it's doubtful that any frontline Tempests used Sabre IIAs: as it is the reference to  reverting to +9 lbs  would refer only to those Tempests still equipped with IIAs at the end of the V-1 campaign, because, as was shown by RolfSeal way back in May, the IIB only used +11 lbs boost.

[9./JG27golani79]

1 hour ago, MiloMorai said:

"... it is their intention to reduce...." is not the same as "shall be reduced" or "will be reduced".

 

Definition of intention for English Language Learners

• : the thing that you plan to do or achieve : an aim or purpose

 

2nd paragraph:

 

[...]and it appears that the engine could be used at the higher boost pressure[...]

 

Also doesn´t sound as if it was definitely clear ..

Just sayin ..

 

Why would the write it like that if it was so sure?

[MiloMorai]

Typhoons of 438, 439 and 440 squadrons were using 150 fuel on the continent.

[Kurfurst]

Its quite clear the Sabre IIA limits remained at +9 lbs, wheter on 130 grade or 150 grade. See AVIA 15/2411 (or 2911) from January 1945 for confirmation. 

[Talon_]

Yes but only if your engine was not upgraded. Tempests were running the mods that allowed +11lbs but before the Sabre IIB existed - because these mods were serialised into production as the Sabre IIB

[Kurfurst]

 

Great analysis, Glen!

[Quinte]

Multiple things :

- Looking at victory claims doesn't give you an accurate view of what was flying at any given moment in time. At least look at the losses too.

- Obviously aircrafts didn't fly the entire campaign with the same engine. At best, the serial gives you the engine it was delivered with. (Check earlier in the thread if you need evidence re. swapping engines, I've posted some.)

- Even then, we know the listing you gave above to.be erroneous in parts, when it comes to the characteristics of aircrafts from each batch. Production Sabre IIb could have been introduced in some late EJ, or in some early NV, but like other characteristics, it doesn't necessarily coincide with the beginning of a new batch.

- The sabre IIa and IIb are the same engine. As explained in "British aero piston engines" the IIb is a prod line standardization of changes made to the IIa, both in production and in the field. There are three differences, all of them necessary to achieve +11lbs: a new shaft to absorb the power, a new boost control capsule to let the supercharger know it can allow up to +11lbs, and a third one I can't remember right now. So any Tempest that was flying during the V1 campaign, and all subsequent Tempests, were actually using a Sabre IIb, whether it was designated as such when delivered or not.

Edited August 22, 2018 by Quinte

[Talon_]

26 minutes ago, Quinte said:

There are three differences, all of them necessary to achieve +11lbs: a new shaft to absorb the power, a new boost control capsule to let the supercharger know it can allow up to +11lbs, and a third one I can't remember right now.

 

Shaft yes, boost control capsule is pretty much just a valve like on any modern supercharger, and the third change is the boost control cam fitted to the throttle unit that changes the ratio of throttle opening rate so that the same two throttle positions are used for both military (unchanged) and full boost power (2lbs more) between the old and new engines (the "ramp" from military to emergency is less linear with the new cam).

[unreasonable]

And Sabre IIB, whether factory produced or field mod was cleared for 11lbs according to it's PNs whether it is flying on 130 or 150 octane, right?

 

Honestly I cannot see what the fuss is about: it is clear to me that the most sensible interpretation of the data shown is that while we could have two Tempest engine variants with 9lbs and 11lbs,  given the time-frame of the BoBP game it would also make perfect sense to have only one, which would have to be IIB on 11lbs.

 

 

[Talon_]

Also to add, any 150 octane Sabre IIA would have been modified to IIB standard by adding a new shaft and boost valve - but probably not control cam as this is a pilot ergonomic issue - in order to run +11lbs in the first place. If it hadn't, the engine would have simply failed.

 

The reason this is not more clearly mentioned is that the Sabre IIB does not exist when this is happening - it's just an upgrade for the existing engine. These parts later went on to be named the Sabre IIB when installed from the factory.

 

[MiloMorai]

7 hours ago, VO101Kurfurst said:

That's a nice collection of victory claims, thank you. It looks like the first claim was made in June 1944 (3 claims made), then its nothing until the end of September 1944 (5 claims made 29-30 September). 4 claims in October, 6 in November. Then action begins in earnest from December.

 

 

 

EJ693 of 486 Sqd flew 16 missions over the continent from 9 - 18 Sept when based at Newchurch.  On 11 Sept even flew an escort mission to the Ruhr.

 

 http://www.hawkertempest.se/index.php/survivors/2015-01-19-19-22-20/ej6932 

 

On 25 August 1944, No 56 Squadron conducted a fighter sweep across the channel to Cassel and Tempests were once more back in action over the continent. In addition to the Newchurch Wing, Nos 274 and 80 Squadrons were engaged in attacks against targets in France

On 25 August 1944, No 56 Squadron conducted a fighter sweep across the channel to Cassel and Tempests were once more back in action over the continent. In addition to the Newchurch Wing, Nos 274 and 80 Squadrons were engaged in attacks against targets in France

Edited August 22, 2018 by MiloMorai

[Talon_]

32 minutes ago, No.41_Glen said:

 

Good points, but let's be conservative.

1) Assume modification from IIA to IIB took place from 1st September 1944

 

This is wrong. Any plane that ran on +11lbs was already modified in August and the parts are still being manufactured and delivered to 150 Wing over summer. In fact they've been serialised into engines being built over that same summer that are then installed into airframes delivered as early as September as brand new engines without retrofit.