Inaccurate performance data for BOB fighters in COD comparing to RL data

[camber]

Dear Crumpp,

I just can't find these arguements compelling where you compare current peacetime FAA (US) procedures and definitions to the RAF in 1940, then state conclusions that are held and argued no-matter how they are contradicted by the rest of the evidence. I understand you have some background in (today's) civil aviation, it may be a good place to start but it is not producing very compelling arguments.

Plus there a lot of assumptions being put into your mix. Your current argument rests on implying new cylinder heads are needed (with consequent large requirements for time and materials), where AP1590/J.2-W (which you posted) refers to a rather more mundane "cylinder head spigot depth modification" (elsewhere referred to as a "top joint modification") which has aleady been done in routine maintainance or at the factory for new engines as Glider and others have said (document from March 40). It would be nice to see some more info on what exactly Merlin Mods 64,77 and 136 entailed (these are the cylinder head mods), but there are a lot of posted documents detailing that the airfield conversions were done very quickly.

The nature of the boost control modification itself rather argues against the relevance of comparing today's civil aviation standards with the 1940 RAF. Drilling extra air channels to convert an existing boost control cutout into a boost pressure setpoint control? Brilliant, ingenious, very seat of the pants. I have a little background in civil aviation too (Australia) and I can't see it happening today

I am not saying the devil's advocate role is not useful. I loved it when you totally offended the Spitfire purists by saying that according to a college course you did, the Spitfire fails control stability design standards developed in the US at the end of the war. There was an interesting point there that the pre 1940s belief that instability was necessary for manouverability was wrong...US engineers figured out that you can have both. This (correct) technical detail about changes in standards does miss the point though that pilots of the time (and today) found the Spitfire a delightful aircraft to fly.

There was also the time when you offended an ex-RAAF fast jet pilot (who also flew Yak 50s) by contradicting him repeatedly on flying in the "buffet", when you stated (correctly) that flight in the buffet regime is wrong because it represents a loss of aerodynamic efficiency and hence turn efficiency. But this (correct) technical detail misses the point that military or aerobatic pilots have often used the first point they can detect the onset of buffet (i.e flying in the "buzz") to stay in proximity to their maximum AoA...any slight deterioration in performance is offset by the ability to detect the point of departure and stay near it.

Bolding text and making statements that "this is a FACT" and "anyone that knows about aeroplanes would know this" I (and I suspect others) find very unconvincing. Generally you have used them to make statements that are correct within a narrow technical context or definition but then become misleading in the historical application to which they have been put.

Cheers, camber

[Crumpp]

I just can't find these arguements compelling where you compare current peacetime FAA (US) procedures and definitions to the RAF in 1940

Convention Relating to the Regulation of Aerial Navigation Signed at Paris, October 13, 1919
(Paris Convention)
THE UNITED STATES OF AMERICA, BELGIUM, BOLIVIA, BRAZIL, THE BRITISH EMPIRE, CHINA, CUBA, ECUADOR, FRANCE, GREECE, GUATEMALA, HAITI, THE HEDJAZ, HONDURAS, ITALY, JAPAN, LIBERIA, NICARAGUA, PANAMA, PERU, POLAND, PORTUGAL, ROUMANIA, THE SERB-CROAT-SLOVENE STATE, SIAM, CZECHOSLOVAKIA AND URUGUAY,
Recognising the progress of aerial navigation, and that the establishment of regulations of universal application will be to the interest of all;

There have been other conventions since but 1919 was the first. Aviation is the same around the world for the most part.

Yes, the Air Ministry of the United Kingdom follows the same rules and concepts as the FAA. Those principles are exactly the same. Once more, the instructions found in every Air Ministry Operating Notes reflect this practice.

Crumpp says:

you will not see technical orders that are applicable to operational units that do not make it into the new edition.

"cylinder head spigot depth modification"

Do you know what a cylinder head spigot is on an engine?

routine maintainance

It is not routine maintenance; it is done at Service Inspection. Do you know the difference?

There was also the time when you offended an ex-RAAF fast jet pilot (who also flew Yak 50s) by contradicting him repeatedly on flying in the "buffet", when you stated (correctly) that flight in the buffet regime is wrong because it represents a loss of aerodynamic efficiency and hence turn efficiency.

You misrepresent this completely. The statement was not using the buffet to find maximum turn performance. He flat stated that maximum turn performance occurs in the buffet. That is not correct and once he clarified that we had no issue.

This (correct) technical detail about changes in standards does miss the point though that pilots of the time (and today) found the Spitfire a delightful aircraft to fly.

Up until the moment they died from it! What the engineer likes and what the pilot likes are not always the same thing. Why let a pilot take a plane someplace it cannot fly?

Generally you have used them to make statements that are correct within a narrow technical context or definition but then become misleading in the historical application to which they have been put.

How can it be technically correct and then wrong in some imagined historical application? Sounds like horse-puckey to me. What I have passed on is true and how it works. There is no point in arguing the same information over and over. Problem is that most aviation historians have no practical aviation experience. In fact, the vast majority of books on aviation history are written by interested amatures who don't have a background in either history or aviation.

What I have said about the Operating Notes is technically, historically, and whatever else you want to attach to the word, "CORRECT". I don't care if you believe it, hate it, or love it.

Cheers,

Crumpp

[JtD]

Is there any evidence of 87 octane fuel used by operational fighter units during BoB by now?

[IvanK]

Quote:
There was also the time when you offended an ex-RAAF fast jet pilot (who also flew Yak 50s) by contradicting him repeatedly on flying in the "buffet", when you stated (correctly) that flight in the buffet regime is wrong because it represents a loss of aerodynamic efficiency and hence turn efficiency.

You misrepresent this completely. The statement was not using the buffet to find maximum turn performance. He flat stated that maximum turn performance occurs in the buffet. That is not correct and once he clarified that we had no issue.

-----------------------------


Just to keep the record straight (and not wanting to re enter the engagement or add to thread drift) on what I actually said. My very last post in that thread regarding Max performance turning and using the Buzz for AOA cueing was:

CRUMPP you said above:

"As for the original premise of this discussion, the effect of a hard buffet for stall warning on turn performance:"

The premise of the discussion was NOT flying in Hard Buffet at all ! but on the very first indication i.e. The "Buzz" or the "Nibble" or the "Burble" ... what ever you want to call it. In a previous post you erroneously said the Buzz and Buffet I described was in fact the stickshaker going off even though in these aeroplanes no stickshaker system was fitted, you also told me that it was only valid technique in FBW aircraft ... even though we were talking about coventional cable/pushrod flight control systems ! You fail to accept that flying on the Buzz was/is a technique practised by Fighter pilots the world over and examples provided in this thread from at my count by 4 independent people/references ... by those that have actually used the technique....including a Spitfire pilot from the Battle Of Britain. "

http://forum.1cpublishing.eu/showthr...=Yak52&page=17

[Talisman]

With regard to the pilot notes, RAF Air Publication (AP) amendments are well known for being behind the times as far as up-to-date common practise at the front line is concerned. It may be many months and over a year or so before an AP is fully updated to reflect what is actually taking place on the ground and in the air.

A fighting force does not wait for the AP to be updated before taking actions that are operationally required to provide an advantage in combat (AP amendments are not a priority when fighting a war). In the mean time, RAF personnel may be informed and corporate knowledge developed by other means of authorised advanced information contained in a variety of communication methods, such as signals, memos, letters, advanced information leaflets (destroyed once formal amendment leaflet is incorporated into the AP), briefings and local training.

The date an Amendment Leaflet is issued is not an indication of when the subject practise was first authorised or carried out. Moreover, the vast number of aircraft AP copies in existence would not have all been amended with updated changes on the same date; different copies of the same AP held across the RAF at squadron and flight level will have different dates recorded on the amendment leaflet record for the incorporation of the amendment. Also, it is not unusual for amendment leaflets to go missing in transit and for a unit to receive an amendment leaflet out of sequence, or for the AP to have a number of missing amendment leaflets; no system is perfect.

In short, I do not believe that it is logical or wise for us or the CloD dev team to treat a set of war time pilot notes as gospel for an exact time frame without taking account of the wider historical context and associated issues (reality check).

[pstyle]

Originally Posted by JtD

Is there any evidence of 87 octane fuel used by operational fighter units during BoB by now?

No.
Just a few suggestions that it was logically possible.

[NZtyphoon]

Originally Posted by Crumpp

Yes, the Air Ministry of the United Kingdom follows the same rules and concepts as the FAA. Those principles are exactly the same. Once more, the instructions found in every Air Ministry Operating Notes reflect this practice.

Problem is that most aviation historians have no practical aviation experience. In fact, the vast majority of books on aviation history are written by interested amatures who don't have a background in either history or aviation.

What I have said about the Operating Notes is technically, historically, and whatever else you want to attach to the word, "CORRECT". I don't care if you believe it, hate it, or love it.

Cheers,

Crumpp

In order: wrong, as I have explained to Crumpp - twice- but I'm probably on his "ignore" list (awww I'm devastated!)

Crumpp shows that "having practical aviation experience" doesn't make for a good historian - just someone who thinks he's right about everything, and Crumpp clearly has no idea of what good historical research entails because he doesn't know how to handle anything that goes against his own beliefs.

Wrong - again - in so many ways. Crumpp cannot be bothered with other people's opinions and cannot be bothered re-examining his own predetermined POV in spite of everything that has been presented in this exceedingly lengthy thread; there is no point trying to reason with this ahistorical chump because he just repeats the same arguments over and over, regardless of any inconvenient facts that happen to get in the way.

[Gabelschwanz Teufel]

Perhaps instead of looking at the issue of pilot notes and revisions through the lens of a civilian "expert", maybe one should ask someone in the military how the "TO" (the US equivalent) system really works. Or better yet, someone with service time in the RAF. Still, from reading this on and off, it will make no difference because he has determined that he's right and reality be damned.

[pstyle]

Originally Posted by Gabelschwanz Teufel

Perhaps instead of looking at the issue of pilot notes and revisions through the lens of a civilian "expert", maybe one should ask someone in the military how the "TO" (the US equivalent) system really works. Or better yet, someone with service time in the RAF.

Even then, we will be dealing with "modern" procedures.

Note especially that these are all post the 1974 Health and Safety Act. (and the 1987 repeal of sections 61 to 76), this does not necessarily make for good historical analysis.

The BoB period RAF cannot be analyised in the absence of reference to photos, pilot notes aand combat reports from the period, which indicate widespread use of 100, and at this stage there is no positive evidence of 11 group or even 12 group use of 87 in spits or hurricanes after may/june 1940.

[camber]

Crumpp:

Originally Posted by Crumpp

Do you know what a cylinder head spigot is on an engine?

Actually, no. One of the advantanges of such a long discussion is that a lot of great documents have been posted. However looking back I can't find any technical references to what precisely these Merlin head mods entailed. Anyone? Crumpp, you posted a while back that it was a modification to change vibration harmonics. Where did that information come from? Although I think the mods are interesting I doubt they would change the conversion story as already discussed.

IvanK:

Was a bit relieved re-reading that thread that my memory of it was correct (though I should have said "hard buffet" and not just "buffet"), I was a bit lazy to not check it and link to it. Assuming my assumption about your past activities is correct and considering tomorrow's date, thank you for your service to this country.

Cheers, camber