Stability and Control characteristics of the Early Mark Spitfires

[NZtyphoon]

Originally Posted by Crumpp

The NACA did a study as part of the stability and control standards on the forces an average pilot can exert.

I am sure that data could easily build an "average joe" pilot.

It would be easy to implement a fatigue model as well.

It is very interesting, btw.

The current FAR's are based in this same research. The formula for minimum stick force per G required in a stick control column aircraft is:



(Weight of Aircraft / 140lbs) / (structural damage limit - 1)

So a 6500lbs aircraft using a stick as the control input and is fully aerobatic at a structural damage limit of 6G:

(6500lbs/140) / 5 = 9.28Lbs per G minimum required.

Please explain how this translates to a computer sim, and how will the developers adapt this formula to cater for the different types of joysticks/rudder pedals used by members of the IL2 community?

[Crumpp]

PS I do owe you an apology.
You said that the design of the Spitfire wing was done at a number of colleges and I asked you which to which you gave me a number. It was a trick question which you fell for.
You may or may not know what is taught at the establishments you named, but you would not know what they use in their lectures unless you had done the course so your list must have been made up.
Also you said Cambridge as one of the establishments. Cambridge isn't a place where you study. Cambridge is in effect an admin centre for 31 Colleges or to be more precise seats of learning and none of them do aerodynamics.

I can tell you that Cranfield is the premier University for Aerospace in the UK its very advanced with their own test fleet of aircraft. We had visiting lecturers from Cranfield come to HMS Daedalus for some of our studies which included Hovercraft

Which has what to do with anything?

I never claimed to go to Cambridge. I went to Embry Riddle. I do have friends who went to other colleges and they also know of the Spitfire's instability.

What does your point have to do with that fact or any fact relevant to this discussion?

Or the fact, it is Cambridge University that published the book??

Cambridge University, Engineering Department, Trumpington Street, Cambridge CB2 1PZ, UK
Tel: +44 1223 332600, Fax: +44 1223 332662

Before coming to Cambridge in October, you must complete this booklet of problems, produced by the Department. It contains questions on mathematics, geometry, mechanics, DC electrical circuits and electromagnetism, to help prepare you for lectures. There is a supporting Website containing guidance notes and links to learning resources (as well as
the booklet itself in PDF format). Your college will send you a username and password to access the material online, and will either send you a hard copy of the booklet, or direct you to print your own copy from the Website. Your
Director of Studies will give you further guidance on tackling these problems, and may ask for the work to be handed in at the start of your first term, for discussion in your first supervisions.

http://www.eng.cam.ac.uk/teaching/index-freshers.html

http://maps.google.com/maps?q=Cambri...m&z=16&iwloc=B

[Glider]

Originally Posted by Crumpp

Which has what to do with anything?

I never claimed to go to Cambridge. I went to Embry Riddle. I do have friends who went to other colleges and they also know of the Spitfire's instability.

I know that you didn't go to Cambridge as to Embury Riddie that may or may not be the case. I do know that when you offerred to debate Longitudional Stability by standards one was to do with roll rates and nothing to do with what you wanted. I believe that one of the other standards you wanted to use is to do with ordering spare parts, not exactly stability. I wouldn't expect a graduate from Embry Riddle to make that kind of mistake, its possible of course but it is a basic error

But you did say that Cambridge and others used the Spitfire wing when you clearly don't know

What does your point have to do with that fact or any fact relevant to this discussion?

Because its another example of you making up statements without foundation to support your case.

Or the fact, it is Cambridge University that published the book??

Cambridge University Press is a publishing house NOT a University. The University is an admin for the collages not a seat of learning and supplies support to the member seats of learning, including publishing.

http://www.eng.cam.ac.uk/teaching/index-freshers.html

http://maps.google.com/maps?q=Cambri...m&z=16&iwloc=B

These tend to prove that you trawled for something to support your statement rather than have actual evidence

Speaking of evidence and more importantly, we are all waiting for your source or evidence re piles of bent wings in the BOB waiting for repair. I produced two pieces of evidence you have have yet to produce anything.

You once accused me of being unprofessional so either substantiate your claim or withdraw it, its the professional thing to do

[Crumpp]

From "Aerobatics Principles and Practice" by David Robson, ex Fighter Pilot,Miltary test pilot (ETPS graduate.)

Right....

Edge of the Buffet is not IN the buffet.




If you have no other guide, the buzz is useful for finding CLmax. Don't fly in the nibble but back off to just before though IF you want maximum turn performance.

Lift varies with angle of attack and airspeed. The highest useful angle of attack is just before the critical angle, about 15 degrees. At this high angle of attack, maximum CL, considerable drag is produced, and if the aeroplane stalls, or the buffet is reached, the drag will increase dramatically. Ideally, sufficient backpressure should be applied to activate the stall warning (if it is operating) on its first note. Alternatively, the very edge of the buffet will need to be used as a guide to maximum CL.


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

You can fly in the nibble if you want, IvanK. However somebody that is turning in the same airplane at the point of smooth air just before the nibble will out turn you. That is how the physics works.

Its not a case of not "wanting" to be in the situation... Operational pilots often find themselves in situations they dont want to be in. The question put was quite specific, a Spitfire MKI no AOA gauges no accelerometers just you the pilot and your basic airframe.

Right.....Again, I would not want to be in that situation with a neutral or unstable aircraft with a light stick force per G and extremely small amount of available stick control.

That why we see charge sheets with "structural failure" and "wings came off in aerobatic flight".

But you did say that Cambridge and others used the Spitfire wing when you clearly don't know
Quote:

Making up what????

Start another thread on this off topic sideshow. Cambridge awards degrees, they published the book, and it is used as a reference in many engineering curriculuums.

If you don't like those facts, tell Cambridge not me.

[Crumpp]

either substantiate your claim or withdraw it

Why don't your read Morgan and Shacklady. They have a list of the serial numbers and known fates of many of the Spitfires.

They even have pictures of the remains of some of the aircraft that shed wings during high speed maneuvering.

Are you going to make me scan them or can you just pick up the book and read it?

[NZtyphoon]

Originally Posted by Crumpp

Why don't your read Morgan and Shacklady. They have a list of the serial numbers and known fates of many of the Spitfires.

They even have pictures of the remains of some of the aircraft that shed wings during high speed maneuvering.

Are you going to make me scan them or can you just pick up the book and read it?

In fact it's much easier going through http://www.spitfires.ukf.net/ which is better researched and better laid out, and more accessible, then M & S.

Originally Posted by 6S.Manu

Infact it's the entire picture... they says those were the accidents reported to them... it's only a speculation that they were the only accidents during all the war as you said since:

1) Was the AAIB the only one actually called to investigate on accidents?
2) How many accidents were not reported?
3) We don't know the AAIB method of investigation: did they need the wreck?... or they could investigate by interviews with the witnesses of the accident?
4) As you says, I repeat, I can be that some accidents not reported as result of a past investigation. A plane is losing its wings during recovery from a dive? The first accident of this kind required an investigation, probably also the second one... but how many until it's clear that the plane can be pull so much and it become ?

1) The body responsible for investigating air accidents before and during WW2 was the AIB (Accidents Investigation Branch) which was responsible for investigating all air accidents. http://www.aaib.gov.uk/about_us/history.cfm
2) Why bother speculating on a question which can never be answered? It's like asking how long is a piece of string.
3) Presumably whatever was available - if a wreck was at the bottom of the sea AIB would not have gone chasing after it.
4)Again, unquantifiable speculation

[bongodriver]

1) Was the AAIB the only one actually called to investigate on accidents?
2) How many accidents were not reported?
3) We don't know the AAIB method of investigation: did they need the wreckage?... or they could investigate by interviews with the witnesses of the accident?
4) As you says, I repeat, I can be that some accidents not reported as result of a past investigation. A plane is losing its wings during recovery from a dive? The first accident of this kind required an investigation, probably also the second one... but how many until it's clear that the plane can be pull so much and it become ?

1) in all probability yes....it's their job, why call in people who aren't qualified?
2) probably a very small amount, in all likelyhood just the events which lead to MIA and unknown fates.
3) as long as the methods produced the answer does it matter?
4) let's not forget that most Spitfire pilots were flying with a squadron and the squadron pilots are all credible eye witnesses to what happens, through all of the recounted stories and biographies etc nobody ever mentioned the Spitfire as being 'particularily' weak or seeing squad mates breaking up with any regularity.

[Crumpp]

See Henshaw

Good stuff...

He says 25 were lost due to structural failure he uncovered in his research. That is quite a few.

That is only the ones that were lost due to total failure as well as the ones we know about. It does not tell us the number of aircraft which flew home with bent wings or the ones that broke up over enemy territory.

To put that 25 unfortunate Spitfires in perspective:

~2488 Spitfire Mk I and II's were produced

2488/25 = 99.52

So for every 100 Spitfires, one was lost to structural failure.

Now let's compare that to the Beechcraft Bonanza which also had some developmental issues with the V-tail that resulted in structural failure. It is the airplane that forged the "Doctor Killer" reputation.

>17000 Beechcraft Debonair/Bonanza's have been built.

Taking structural failures from 2007 on back we find that 148 airframes have been lost. We have much better records of a peacetime GA aircraft.

http://www.thomaspturner.net/infligh...ups%20NTSB.htm

17,000 / 148 = 114.8

So, For every 115 Beechcraft Debonair/Bonanza's built, ONE has experienced structural failure.

http://www.tsgc.utexas.edu/archive/g...ics/vtail.html

I think the early Mark Spitfire would have had the same reputation in peacetime as the Bonanza due to its high rate of structural failure.

The events of WWII overshadowed the longitudinal instability issue in the early Mark Spitfires.

[Crumpp]

4) As you says, I repeat, I can be that some accidents not reported as result of a past investigation. A plane is losing its wings during recovery from a dive? The first accident of this kind required an investigation, probably also the second one... but how many until it's clear that the plane can be pull so much and it become ?

#4 Again, unquantifiable speculation

It is not speculation. It is a fact, the early mark Spitfire had neutral to unstable longitudinal stability at normal and aft CG. It is a fact, the controls were too light and too effective.

This combination is why you see the warnings in the Operating Notes.

It was real and it could kill you if ignored.

[Glider]

Once again you are putting your own spin onto a paper that it presented to you.

Originally Posted by Crumpp

Good stuff...

He says 25 were lost due to structural failure he uncovered in his research. That is quite a few.

That is only the ones that were lost due to total failure as well as the ones we know about. It does not tell us the number of aircraft which flew home with bent wings or the ones that broke up over enemy territory.

To put that 25 unfortunate Spitfires in perspective:

~2488 Spitfire Mk I and II's were produced

2488/25 = 99.52

Where does he say only Mk 1 and II's? He doesn't so lets apply your logic to all the spits produced in the war
23,000/25 = 920

So for every 100 Spitfires, one was lost to structural failure.

So for every 920 Spitfires one was lost to structural failure

Now let's compare that to the Beechcraft Bonanza which also had some developmental issues with the V-tail that resulted in structural failure. It is the airplane that forged the "Doctor Killer" reputation.

>17000 Beechcraft Debonair/Bonanza's have been built.

Taking structural failures from 2007 on back we find that 148 airframes have been lost. We have much better records of a peacetime GA aircraft.

http://www.thomaspturner.net/infligh...ups%20NTSB.htm

17,000 / 148 = 114.8

So, For every 115 Beechcraft Debonair/Bonanza's built, ONE has experienced structural failure.

So for every 920 Spitfires produced in the war ( I could increase this number to all spits built) One experienced a structural failure.
In other words you are about 8 times safer in a Spit in wartime than in a peacetime Bonanza

I think the early Mark Spitfire would have had the same reputation in peacetime as the Bonanza due to its high rate of structural failure.

I think the early Mark Spitfire would have had a much better reputation in peacetime than the Bonanza due to its much safer record iro structural security