Stability and Control characteristics of the Early Mark Spitfires

[NZtyphoon]

Originally Posted by Crumpp

The RAE did not have a standard for stability and control.

ONCE again, there is nothing else in the Operating Notes in either the Typhoon or the Tempest that pertain to any kind of longitudinal stability issue. Had their been an issue, it would reflect in the cautions.

This is in sharp contrast to the early Mark Spitfires whose Operating Notes are filled with warnings of symptoms that are the result of longitudinal stability.

The tail problems turned out to be due to elevator flutter and were cured by modifying elevator balance, but that didn't happen until very near to the end of the war.

The Typhoon's tail problems had nothing to do with the longitudinal instability described in the Pilot's Notes. The Tempest did not suffer from "low velocity tail flutter" yet also displayed slight longitudinal instability.

And, BTW the website is completely wrong - the rudder balances, which were at the root of the tail problems, were modified in 1943 - there was no problem with the elevator balances. From early 1944 new production Typhoons, and some earlier ones, adopted Hawker Tempest horizontal tailplanes and elevators which had a larger area - with the small tailplanes and a full weapons load of either 8 RP-3s or 1,000 lb bombs the longitudinal stability deteriorated.

Your comment was the Hurricane, Typhoon and Tempest had near perfect longitudinal stability - no comment about a "longitudinal stability issue." Fact is you were wrong, once again - both aircraft were slightly unstable longitudinally.

If the RAE had no standards for stability and control it meant they were unable to comment on the stability and control of aircraft they tested - read the 1938 report carefully, it is most illuminating.

The Spitfire PNs describe control and g-limits in rough air and caution pilots against making high-speed manœuvres in such conditions, something also covered in Pilot's Notes General.

[robtek]

The thing that made the Spitfire instability special was the very light elevator plus the very short stick travel for large reactions, the Hawker designs were so normal in this aspect, that it isn't even mentioned.

I think for a unbiased reader it shows very clear, that in this thread everything possible is used to indirectly attack the OP.

I shure hope for the same unbiased support for the other planes that hopefully will be discussed.

[taildraggernut]

I know...this is just another one of those pesky reports by that class of people who know nothing of the subjet i.e. a pilot, but at least this one doesn't have 60 years of faded memory and biassed oppinion (he also flies a 109)

http://www.vintagewings.ca/VintageNe...Rob-Erdos.aspx

My first airborne impressions of the Hurricane were a bit of surprise. It’s…well, wobbly. During maneuvers the Hurricane is heavy, but pleasant. Rudder coordination isn’t optional, but not uncharacteristic of its vintage. Attempts at trimming the aeroplane are never fully satisfactory, and you can’t really take your hands off the stick for very long. The control forces are quite high; a situation not aided by horrendous amounts of control system friction. In this regard, comparisons are inevitable. Wartime lore has it that while the Spitfire was more agile, the Hurricane was a more “stable gun platform”. Sorry. In terms of classical stability the Spitfire wins by a small margin on all counts. Nevertheless, the Hurricane’s firm control feel gives it a sense of solidity that would complement an adrenalin-charged young fighter pilot.

[taildraggernut]

Originally Posted by robtek

The thing that made the Spitfire instability special was the very light elevator plus the very short stick travel for large reactions, the Hawker designs were so normal in this aspect, that it isn't even mentioned.

I think for a unbiased reader it shows very clear, that in this thread everything possible is used to indirectly attack the OP.

I shure hope for the same unbiased support for the other planes that hopefully will be discussed.

Nothing to do with attacking the OP, everything to do with backing up the opposed oppinions, what this proves is that nobody who disagrees with the OP is doing it for simple emotional reasons, there are plenty of sources of information to back it up, it's up to the OP to prove without doubt his claims, every claim he has made has had a very valid counter argument, one could argue that someone dedicating so much attention to claims such as the OP's is probably the one doing it for emotional reasons.

[Robo.]

Originally Posted by taildraggernut

one could argue that someone dedicating so much attention to claims such as the OP's is probably the one doing it for emotional reasons.

Very much so.

I really enjoyed reading the attached documents and opinions in this thread, thank you very much for that.

Taildraggernut cheers for the Rob Erdos article, great reading.

[robtek]

The problem is, that crumpp doesn't present claims, he presents documented facts!

The claims are coming from those, who are unwilling to accept those facts.

To recapitulate those facts, as i understood them, in concentrated form:

1. The early Spitfire marks had a inherent longitudal instability which led to the manufacturer-fix with bob-weights.

2. The stick forces for the elevator were extraordinarily small in the Spitfire.

3. The stick travel was extrordinarily small for large reactions.

It really doesn't matter how good the pilots then were able to cope with those circumstances, it should be reflected in game that the plane doesn't fly itself, but has to be flown, and that with precise, small inputs for the elevator.

Also the tests shown by crumpp say that if one doesn't ride the buffet in a turn, but gets into the buffet, the turn performance is reduced drastically.

It is up to the fm programmer to make it possible to feel the difference in game.

Every aircraft has its quirks, and i think we want them all represented in this game.

[taildraggernut]

The problem is, that crumpp doesn't present claims, he presents documented facts!

No, he presents documents and interprets them to an extreme, with Crumpp this apparent instability is 'total' and should render the Spitfire dangerous to fly, simply not true.

The claims are coming from those, who are unwilling to accept those facts.

Funny how despite a similar weight of documented evidence is labeled aas 'claims' when on the other side.

1. The early Spitfire marks had a inherent longitudal instability which led to the manufacturer-fix with bob-weights.

in the MkV which had a different engine, all up weight etc.....oh and was about to go into service with the US air force....who apparently heard it was a bit 'unstable'

2. The stick forces for the elevator were extraordinarily small in the Spitfire.

Yes, as my link to the NACA report showed 'desirably light'

3. The stick travel was extrordinarily small for large reactions.

as a real life pilot I can say that sounds like a perfect situation, who wouldn't like a responsive ride?

It really doesn't matter how good the pilots then were able to cope with those circumstances, it should be reflected in game that the plane doesn't fly itself, but has to be flown, and that with precise, small inputs for the elevator.

I must be using a different game, it certainly isn't a hands off aircraft in game, but I sure would like some more of that responsiveness.

Also the tests shown by crumpp say that if one doesn't ride the buffet in a turn, but gets into the buffet, the turn performance is reduced drastically.

Which is quite true of any aircraft, luckyly the Spitfire was so responsive that a pilot barely needed any effort to take the aircraft out of the buffet.

It is up to the fm programmer to make it possible to feel the difference in game.

Every aircraft has its quirks, and i think we want them all represented in this game.

Yes, I agree, I am really looking forward to the promised 109 topic.

[robtek]

Originally Posted by taildraggernut

No, he presents documents and interprets them to an extreme, with Crumpp this apparent instability is 'total' and should render the Spitfire dangerous to fly, simply not true.

I still have to find crumpps claim that the Spitfire is dangerous to fly, failed so far.

Funny how despite a similar weight of documented evidence is labeled aas 'claims' when on the other side.

Well, none of this evidence said different from crumpps documents

in the MkV which had a different engine, all up weight etc.....oh and was about to go into service with the US air force....who apparently heard it was a bit 'unstable'

Yes, the MK Va with the same flying characteristics as the Mk I / II as the airframe is identical apart from small changes.

Yes, as my link to the NACA report showed 'desirably light'

I haven't found your link, but i found that in the NACA report:

In turns with speeds high enough to prevent reaching
maximum lift coefficient because of the excessive accelerations
involved, the small static longitudinal stability
of the Spitfire caused undue sensitivity of the normal
acceleration to small movements of the stick. As shown
by the time histories of high-speed turns (figs. 15 to 1,
it was necessary for the pilot to pull back the stick and
then ease it forward almost to its original position in
order to enter a turn rapidly without overshooting the desired
normal acceleration. Although this procedure appears
to come naturally to a skillful pilot, flight records
from other airplanes show, that a turn may be entered rapidly
and the desired normal acceleration may be held constant
by a single rearward motion of the stick, provided
the static stability of an airplane is sufficiently large.
By careful flying, the pilot was able to make smooth turns
at high speed, as shown by figures 17 and 18. Ordinarily,
however, small movements of the stick caused appreciable
variations in the normal acceleration, as shown in figures
15 and 20.

as a real life pilot I can say that sounds like a perfect situation, who wouldn't like a responsive ride?

Now, that is pure blandishing.

I must be using a different game, it certainly isn't a hands off aircraft in game, but I sure would like some more of that responsiveness.

Yes, more in the elevators, much less in the ailerons.

Which is quite true of any aircraft, luckyly the Spitfire was so responsive that a pilot barely needed any effort to take the aircraft out of the buffet.

As it barely didn't need any effort to get into the buffet if not careful flown.

Yes, I agree, I am really looking forward to the promised 109 topic.

Me also.

[taildraggernut]

I still have to find crumpps claim that the Spitfire is dangerous to fly, failed so far.

One only has to look at the bigger picture the chap is painting to realise it, by carefull examination you will see he is suggesting 'extreme care' must be taken to fly it, the penalties for not doing so range from complete loss of control to airframe failure, so even though the specific words were not used the ultimate impression Crumpp is giving is of a 'dangerous' aircraft.

Well, none of this evidence said different from crumpps documents

and thats the craziest part, it's only Crumpps own interpretation of those documents that paint such a dire picture, the most noteable instance has been the graphs showing the various stability tests, all of which show an aircraft with a very gentle divergent amplitude which is in technical terms 'unstable' but not to any degree as to be of concern, so Crumpp's own evidence works against him.

Yes, the MK Va with the same flying characteristics as the Mk I / II as the airframe is identical apart from small changes.

the same airframe with a different engine and all up weight, given that there were apparent differences between the MkI and MkII how can it be so?

I haven't found your link, but i found that in the NACA report:

Seek and ye shall find....

http://history.nasa.gov/monograph12/ch4.htm

Now, that is pure blandishing.

I fail to see where I am flattering you?

Yes, more in the elevators, much less in the ailerons.

Yes, I can go with that

As it barely didn't need any effort to get into the buffet if not careful flown.

Lucky all those chaps with 10 hours on type and 0 combat experience were very careful

Me also.

I have a feeling we are in for a long wait

[Al Schlageter]

I think it is worth re-posting the words of an aeronautical engineer who spent a lifetime practicing his profession over one who hasn't:

FIGURE 4.5. Supermarine Spitfire airplane. A high-performance fighter noted for its role in the Battle of Britain and throughout WW II, the Spitfire had desirably light elevator control forces in maneuvers and near neutral longitudinal stability. Its greatest deficiency from the combat standpoint was heavy aileron forces and sluggish roll response at high speeds.

http://history.nasa.gov/monograph12/ch4.htm