Spitfire Mk IX - stability issues

[Crumpp]

Can't seem to find your email Izzy in my Address book.  Gotta clean it out because it has gotten so large I am losing emails addy's!  If you still have mine shoot me an email real quick and I will send you the report.

Crumpp

[gripen]

Originally posted by Crumpp
Just check out RAE 1231.  The Spitfire could not come anywhere near it's calculated rate of roll due to the pilots ability to apply the necessary stick forces.

I have the RAE 1231 right front of me and I can't find such statement from it. The roll rate curves are for 50 lbs stick force which should be reachable for a average pilot.

Originally posted by Crumpp
1. The curve in the NACA roll rate report is the average of only 4 measured rolls. 2 are below the curve, 1 is on the curve, and 1 is WAY above the curve.

Well, apparently you are talking about gun camera film measurements now. These have nothing to with the instrumented measurements in the RAE.

gripen

[Angus]

I wonder how the Spit VIII did at rolling. It was not clipped, however had a much stiffer wing than prefious models. My guess is a lot better than the IX, however worse than clipped.
But nothing rolled as easily as a 190....

[Crumpp]

I have the RAE 1231 right front of me and I can't find such statement from it. The roll rate curves are for 50 lbs stick force which should be reachable for a average pilot.

You need to look on page 3 of the report.  On the table listing the A.D.M. standard time to 45 degrees value and the actual measured rate of roll average to 45 degree.  It is right next to the utterly dismal aileron reversal speed of 580mph EAS for the standard wing Spitfire.

The normal wing spitfire measured results were almost twice what calculated results say the roll rate should be at.

Well, apparently you are talking about gun camera film measurements now. These have nothing to with the instrumented measurements in the RAE.

No I am talking about the measured results.  You copy of the report does not include the actual roll plots??

Crumpp

[gripen]

Originally posted by Crumpp
You need to look on page 3 of the report.  On the table listing the A.D.M. standard time to 45 degrees value and the actual measured rate of roll average to 45 degree.  It is right next to the utterly dismal aileron reversal speed of 580mph EAS for the standard wing Spitfire.

Well, you need to understand what that table means. These are calculated banking times at 400mph and are based on 50 lbs roll rate curves (fig.6). So the results match exactly measured roll rates.

Originally posted by Crumpp
No I am talking about the measured results.  You copy of the report does not include the actual roll plots??

The graph which contains four curves for the Fw 190 (fig.5) is based on gun camera films.

gripen

[Charge]

According to NACA report the clipped wing Spit could match the 190 in rolls only in a narrow speed range, otherwise it was inferior.


Don't remember how big the gap was though...

-C+

[Crumpp]

Well, you need to understand what that table means. These are calculated banking times at 400mph and are based on 50 lbs roll rate curves (fig.6). So the results match exactly measured roll rates.

I understand exactly what that table means GRIPEN.

You need to learn to read English better.  The report clearly states the Spitfire could NOT reach its calculated roll rate as well as the table reflecting this!

The graph which contains four curves for the Fw 190 (fig.5) is based on gun camera films.

Yes ONE of the Graphs in the report is this table.  NOT the one I am talking about.

The report clearly states both the Typhoon and the standard wing spitfire are down on the ADM 295 criteria and cannot come near their calculated rates.

According to NACA report the clipped wing Spit could match the 190 in rolls only in a narrow speed range, otherwise it was inferior.

Actually the clipped wing spit does quite well.  The most interesting was the Mustang, which according to this report actually beats the 190 at high speeds.  The USAAF tactical trials between a P51B have a different result though.  According to them the FW-190 is superior in the roll at all altitudes and speeds.
I tend to think the FW-190A tested in those trials did not have such stiff ailerons.

Crumpp

[gripen]

Originally posted by Crumpp
I understand exactly what that table means GRIPEN.

You need to learn to read English better.  The report clearly states the Spitfire could NOT reach its calculated roll rate as well as the table reflecting this!

Your problem is exactly that you can't understand the table in the page three. The A.D.M. standard time is a requirement calculated from the wing area and only the Mustang reached this standard. The roll rate curves (fig.5) are measured max steady roll rates and using these values the time to bank 45 deg can be estimated following the procedure described above the table.

Originally posted by Crumpp
Yes ONE of the Graphs in the report is this table.  NOT the one I am talking about.

Well, I quess you are talking about the fig.2 or fig. 4 which both actually contains around 20 or more data points not 4 like you claimed above.

gripen

[VO101_Isegrim]

[Crumpp]

Your problem is exactly that you can't understand the table in the page three. The A.D.M. standard time is a requirement calculated from the wing area and only the Mustang reached this standard. The roll rate curves (fig.5) are measured max steady roll rates and using these values the time to bank 45 deg can be estimated following the procedure described above the table.

Break out your Swedish-English dictionary and start looking up words in that report.  It is spelled out in black and white Gripen.  No speculation no thought needed.  THEY TELL YOU THE RESULTS!  Only the Mustang reached its exact measured results is correct.  The FW-190 was .07 seconds off its calculated time.  

The Spitfire was calculated to roll 45 degrees in .85 seconds at 400mph.  It could only roll 45 degrees in 1.35 seconds because in the formula they assume 1/2 second for the pilot to apply the stick forces and a 1/4 second for the plane to reach max rolling velocity for 45-degree bank.

1.  Either the pilot cannot apply the stick forces in under a 1/2 second at 400mph.

2.  The plane does not respond and cannot reach max rolling velocity in a 1/4 second.

The rolling ability of the Spitfire was a liability in a dogfight leaving the plane unable to change direction quickly compared to the FW-190A.  It could turn tight circles but was not very "nimble".
 


Crumpp

[Angus]

Crumpp
Even within a Spitfire variant, no two planes rolled the same, given the same pilot. That was especially marked with the earlier models, the fixes most markedly being executed on the Mk V series.
Each and every Mk V had to be calibrated, and often a set of ailerons working badly on one plane did a good job on another! There were "rogue" Spits in most squadrons.
These problems were overcome in later models as the wings became stiffer.
The clippings were a short solution in the start, but turned out to be something to stay when combat alts dropped and speed+roll were more important than turns and ceiling.
Oh, and this:
" It could turn tight circles but was not very "nimble". "

You should see how a Spitfire can be whipped about, - I've had the fortune to see it. It's bloody well nimble I'll tell you


P.S. I thought Gripen was Finnish? Anyway, be it Finns or Swedes, those are notorious for being multi-language persons. Can you read Swedish?

[VO101_Isegrim]

I though you liked anecdotal evidence, Angie.


Here`s more :


This if form Alex Heshaw, the Chief pilot of the Castle Bromwhich Spitfire plant. He basically flew hundreds of Spitfires after they left the factory and were tested for airworthyness.


"I loved the Spit, every Marks of it. But I must admit, that altough later Marks were much faster, they were also progressively inferior to previous Marks in manouveribility. When we checked how a Spit behaves during roll, we counted how many complete rolls we could do under a given time. With the Mark II and V, we did 2 1/2 rolls, but the Mark IX was heavier, and only capable of 1 1/2 rolls. The later, more heavier versions could do even less. Designing an aircraft is about finding balance. It`s hardly possible to improve performance without degrading other properties of the aircraft. "

These problems were overcome in later models as the wings became stiffer.

Yep, but not until the Mk 21 (luv to see roll data for that one).

Jeffrey Quill :

So we were not the only ones in trouble in 1940. The metal ailerons solved the immediate problem but the non-repeatability difficulty persisted and I always felt that the lateral control characteristics fell far short of perfect at high indicated airspeeds. Joe Smith believed this too. He began to plan a fundamental change in the aileron design, but it was not possible to introduce this until the arrival of the stronger and stiffer wing in the Mk 21 series.

P.S. I thought Gripen was Finnish?

I believed that one, too, but since every single guy from Finnland seems to be an extremely nice, friendly and cheerful guy, which Gripen is not, I am quite sure Gripen originates to Sverige, and not the Soumi. Just like his nick.

[gripen]

Originally posted by Crumpp
Break out your Swedish-English dictionary and start looking up words in that report.  It is spelled out in black and white Gripen.  No speculation no thought needed. THEY TELL YOU THE RESULTS!

Please quote that part of the report which says that the Spitfire failed to reach it 's calculated  rate of roll as given in the fig.5 and NACA 868.

Basicly you are mixing requirement for time to bank 45 degrees (A.D.M. standard) and measured peak roll rates in the fig.5.

gripen

[Crumpp]

Even within a Spitfire variant, no two planes rolled the same, given the same pilot.

Your absolutely right.  In the report we see the absolutely worst of three FW-190's being tested.

You should see how a Spitfire can be whipped about, - I've had the fortune to see it. It's bloody well nimble I'll tell you

I am sure it is and I am jealous that you got to see it!  However have you ever seen it with an FW-190 whipping about the air?

P.S. I thought Gripen was Finnish? Anyway, be it Finns or Swedes, those are notorious for being multi-language persons. Can you read Swedish?

Since you ask, bro.  I am only fluent in Vietnamese, Spanish, and a good bit of German.  English is of course, my native language.
Ong Khoe Khong, Ban toi??

Crumpp

[thrila]

Isegrim i dont believe that the 1st quote is  quite correct.  I've got the actual quote in a book somewhere.  It's quite a bit different, whoever put that quote on the net did a poor job.  I can't remember it word for word but he performed flick rolls, releasing the controls and counting how many rolls it performed without imput.  No timing was involved.  It wasn't a measurment of an aileron roll, more of the aerobatic qualities of the spit decreasing as it gained weight with each mark.