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

[Osprey]

Originally Posted by winny

At the end of the day I don't give a shit what you think. I value people who were there, and who were writing diaries at the time over your desperate clinging to a meeting that was held when Britain was in the process of re arming for a war they were expecting in 2 or 3 years. I mean.. Who exactly are you? Actually don't answer that, I don't care.

He is Biff, and he hates manure.

[Skoshi Tiger]

Originally Posted by Crumpp

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

Cheers,

Crumpp

In the Merlin engine, it is my understanding that, the spigots were on the cylinder liners. The Cylinder Head had recesses that accepted the spigots (presumable to ensure accurate alignment).

I don't think any other spigots (if any) on the cylinder head have anything to do with the modification.

Cheers!

[Crumpp]

IvanK,

This was my reply to you on the buffet subject. I would encourage people to read that thread. Some good information and some good insight. Stability and control is just about my favorite subject when I was in school. It always amazed me how much of difference it makes in the outcome of an aircraft. you can have the best performance on paper that is unrealizable in the air, all due to stability and control issues. It was such a new thing during WWII, too.

http://forum.1cpublishing.eu/showpos...&postcount=174

I told you the truth. I was not disrespectful. I just backed up what I had to say and did not back down.

It was not "technically correct but historically inaccurate". It was just correct.



Is that like a new classification of information? Ha ha ha!! While this is correct, it is not historically correct, historically, they were wrong but right as I see it because technically they were not correct.



All I said was this:

Ideally the very first hint of it...... No, Ideally you have none at all and are at the point just before any buffeting occurs. That is also what the Spitfire Mk I notes relate

From CAA Flight Instructors Guide:

Secondly, you should be aware that experiencing any buffet will reduce the rate of turn because of its effects on drag and L/D ratio. Therefore, if the stall warning is not operating, and the lightest of buffets is used to determine maximum CL, performance is degraded, and the aeroplane will not be turning at its maximum rate.


http://www.caa.govt.nz/FIG/advanced-...ate-turns.html

[Crumpp]

In the Merlin engine, it is my understanding that, the spigots were on the cylinder liners. The Cylinder Head had recesses that accepted the spigots (presumable to ensure accurate alignment).

I don't think any other spigots (if any) on the cylinder head have anything to do with the modification.

You are very close. There are lots of spigots on an engine. They can be plugs, cylinders, etc...

You are also right in the cylinder liners form the spigot on many engines.

[NZtyphoon]

Originally Posted by Crumpp

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

Crumpp's conundrum

Everbody's Wrong

[Seadog]

[QUOTE=NZtyphoon;414492]Crumpp's conundrum

Well put...

[Gabelschwanz Teufel]

Originally Posted by pstyle

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.

Not the point. The point being that military regs are often supplemented. These supplements can take several forms in that entire pages can be replaced, paragraphs, lines down to individual words stricken or added. Depending on who was in charge of updating the pages could be removed, pen and ink changes made, etc. Or they could have been shoved in the back. The point being that new printed manuals including the latest revisions ARE NOT CONSTANTLY CHURNED OUT LIKE SAUSAGES just because something has changed. Maybe now. Maybe in the civilian world. Not in the military world. Not during wartime and certainly not now. Someone is hanging their hat on the utter dreck that is doesn't say in his particular version of the pilots notes that the operational changes for 100 octane use don't seem to be included. Nor would they if the changes were made after the printing of that series. That's what supplements are for. Spewing some arcane nonsense about some 1919 treaty or something is just more noise trying to justify an position based on what he knows in the civilian aviation world and not based on wartime exigencies or military operation.

[camber]

Well I already contributed to re-derailing a many times derailed thread so I will persist

To me this seems an example of taking a correct technical fact and using it it go somewhere misleading. In a black and white world that would be impossible, but bear with me.

Crumpp:

All I said was this:

Quote:
Ideally the very first hint of it...... No, Ideally you have none at all and are at the point just before any buffeting occurs. That is also what the Spitfire Mk I notes relate
From CAA Flight Instructors Guide:

Quote:
Secondly, you should be aware that experiencing any buffet will reduce the rate of turn because of its effects on drag and L/D ratio. Therefore, if the stall warning is not operating, and the lightest of buffets is used to determine maximum CL, performance is degraded, and the aeroplane will not be turning at its maximum rate.


Yes, any buffet, even the mildest "buzz" represents some flow separation and a degradation in turn performance. This is true even though it is referenced in a New Zealand CAA website and we are very suspicious of those in Australia

So why do historical military pilots and aerobatic pilots (not talking FBW here) seem to think flying at the onset of just detectable buffet a good idea? Are they all misguided and should be told the truth?

Perhaps instead they know what they are doing and do it because it is a practical tool to stay as close as possible to the AoA for a maximum rate turn. In theory some turn performance is lost this way but there is no comparable signal to tell them how far they are under the optimum (so they can apply more pitch input). Of course the aircraft design plays a part in terms of buffet "depth"...if the aircraft departs very soon (with further pitch input) after the buffet onset is felt, or buffet was immediately "hard" it would not be a good idea to se this technique. Another technique would be to continuously detect flow separation, back off then redetect, but this doesn't seem very practical to me. But unfortunately I feel sick for hours after doing just an (approx) 2G turn for 360' so I don't know

Of course a plane design that will take a maximum pilot stick deflection and apply exactly the optimum elevator deflection to achieve optimum AoA without any flow separation is good, but we need the microprocessor in avionics to get there I think.

But to me that covers how context is important for technically correct "facts" to be useful in the discussion.

Cheers, camber

[Crumpp]

So why do historical military pilots and aerobatic pilots (not talking FBW here) seem to think flying at the onset of just detectable buffet a good idea? Are they all misguided and should be told the truth?

Couple of reasons....

1. If you don't have a stall warning device or AoA indicator then flying to the nibble and backing off is the correct technique. Read my last post in that thread and you will see once IvanK clarified his statement, we agreed.


2. See point #1 for most aerobatic aircraft.

Another technique would be to continuously detect flow separation, back off then redetect, but this doesn't seem very practical to me. But unfortunately I feel sick for hours after doing just an (approx) 2G turn for 360' so I don't know

That is exactly what you do.

You can read the Spitfire Mk I notes and see that it is in fact....correct.



Notice in paragraph 38 turning circle it instructs to not buffet the aircraft for a minimum radius turn and relax the stick pressure (move the stick forward)!!

The point being that new printed manuals including the latest revisions ARE NOT CONSTANTLY CHURNED OUT LIKE SAUSAGES just because something has changed.

The RAF republished sections as needed. That is a fact. The incorporated Amendment List was noted at the top of the reprinted section so that the operator could confirm he had the latest updates.

For example, the Hurricane II Volume I shown here incorporates Amendment List Number 42:



The amendment list's that are published but not incorporated are the responsibility of the operator to add to the Operating Notes.

Those amendments are to be logged in the space provided at the front of the Operating Notes:



To complete the update, the operator is instructed to paste in and replace the old text with the changes noted in the Amendment.

Here you can see that an amendment was properly added to the Operating Notes by the Operator:

Crumpp says:

It is a fact that conversion of all operational Spitfire Mk I's was important enough to warrant a warning in paragraph 1, operating limitations of the Pilots Operating Notes in January, 1942.

We can definitely say that full conversion did not take place in June 1940 or earlier as no such warning exists in the Operating Notes.

The only operational evidence of full conversion to 100 Octane presented in the thread is the January, 1942 Operating Notes for the Spitfire Mk I.

That being said, I can also tell you for a fact ALL Spitfire Mk II's were using 100 Octane in June of 1940.

[Crumpp]

BTW, the RAF does the same with their Operating Notes that the FAA requires of any certified General Aviation Aircraft in use today.

It is what was agreed upon by convention!!