Spit/109 sea level speed comparisons in 1.08 beta patch

[JtD]

This is a Spitfire V with metal covered ailerons, tested up to 300 mph. The Spitfire I/II with fabric covered ailerons are a lot worse, and at 400 mph IAS pretty much hopeless - ineffective ailerons combined with a rather flexible wing. British tests indicate a roll rate of about 12°/s at 400 mph with 50 lbs stick force for early Spitfires - in other words half a minute for a 360° roll.

Also sorry for the cheap joke above, but I would say that while people may not disagree on the math, they may very well have different opinions regarding the input and different interpretations regarding the output. I'd also say that anecdotal evidence is valuable in getting input and interpretation right. For example, popular numbers regarding sea level top speed show the F4F to be faster than the A6M-2, however, anecdotal evidence from both sides agrees that the A6M-2 could and would outrun an F4F. A good enough indication that the numbers are not plausible and some research is warranted...but data for the A6M-2 just isn't around in quality and quantity as it is for say Spitfires and 109's.

[NZtyphoon]

Originally Posted by SlipBall

From the 1941 study, it sounds to me that hi-speed rolling was not a strong point

Rolling was never really a Spitfire strength, partly because of the large area of wing tip outside of the aileron; the clipped-wing Spitfires had a better roll-rate at all speeds than those with conventional wing tips while those with pointed, high altitude tips were worse. Another part of the problem was the fabric covered ailerons, still fitted to the NACA Spitfire Va, which tended to "balloon" at high speeds, further reducing their effectiveness.

[Kurfürst]

Originally Posted by NZtyphoon

Another part of the problem was the fabric covered ailerons, still fitted to the NACA Spitfire Va

Which is why the NACA report specifically notes that metal ailerons were fitted to the Spitfire Mark VA tested, right?

[Igo kyu]

Originally Posted by JtD

1+1=10

As you may know, he's counting, correctly, in binary.

[Kurfürst]

Originally Posted by Matt255

I also don't see what the 109 slats have to do with rolling or why the plane would be more stable because of them.

Because leading edge slats were fitted for exactly to this reason. Its no coincidence that slats cover the wing area ahead of ailerons, and maintain steady airflow without stalling at that part of the wing. Slats allow for higher Angle of attack without stalling - meaning the airplane is still controllable is rolling plane. The brief aileron snatching noted on the 109E while the slats deployed, until fully open is also due to this reason. It was fixed on later models of the 109 though, either through the redesign of the wing or through the redesign of the slat actuating mechanism.

Designers always aimed to maintain aileron control near the stall, ie. that the wing root would stall sooner than the part before the ailerons, so that ailerons remain effective. Slatless airplanes typically aimed for this by using washout, a sort of twist in the wing that gave the outer wing less AoA in any flight condition, and a result delayed the stalling point and made the ailerons effective longer. This of course decreased the lift generated by the wing in all conditions, since lift is more or less equal to wing area x AoA. Though slats do the same, their plus side is that they only deploy when needed, and otherwise the aircrafts wings develop their full lift potential. Therefore, they combine the best features for high speed flight, TO/Landing and turn fight.

[SlipBall]

Originally Posted by Kurfürst

Which is why the NACA report specifically notes that metal ailerons were fitted to the Spitfire Mark VA tested, right?

I did see that in the report...back then, from the graph, would it be safe to watch for/anticipate that a pilot would favor/maybe even trained, to favor doing a roll to the right.

Also, I'm always amazed at your sig, taxiing must have been hell with that line of sight he has, I wish it was modeled in this sim as-well (our pilot seems to sit just a little higher). Do you have any history of the plane and pilot.

[NZtyphoon]

Originally Posted by JtD

This is a Spitfire V with metal covered ailerons, tested up to 300 mph. The Spitfire I/II with fabric covered ailerons are a lot worse, and at 400 mph IAS pretty much hopeless - ineffective ailerons combined with a rather flexible wing. British tests indicate a roll rate of about 12°/s at 400 mph with 50 lbs stick force for early Spitfires - in other words half a minute for a 360° roll.

My bad -the NACA Spitfire had metal covered ailerons, I should have absorbed the first sentence before reading the report - still, that does not invalidate anything I said about the damping effect of the wingtips on the Spitfire's roll-rate. A report on a clipped wing Spitfire V vs standard bears this out:




It is interesting to see how small aerodynamic alterations can alter flight characteristics - the total area of the wingtips removed was 12sq ft but, because this was all outboard of the ailerons, removing the wingtips increased the aileron's effectiveness up to 25,000 feet. It probably increased the torsional stiffness of the wings as well.

Just for interest the P-47N also showed the benefits of "clipped" wings:

[Matt255]

And here is a perfect example of what I was refering to, that being how two people can read 'pilot accounts' and get different results

I think in that case, the pilots got different results.

Unless you really try very hard to make one plane appear better or worse than the other, ie abusing historical pilot reports to support your point of view. But who cares.

I generally base my idea of how these planes compared (maneuverability wise), on reports of pilots, who flew both (or more) types. And most of those reports fit each other exceptionally well. Which might not be the "correct" approach, but atleast it rules out some bias.

Originally Posted by Kurfürst

Because leading edge slats were fitted for exactly to this reason. Its no coincidence that slats cover the wing area ahead of ailerons, and maintain steady airflow without stalling at that part of the wing.

(sorry for cutting your post)

I'm totally aware of that and how slats work, but i don't think that's what macro meant when he compared slow speed rolling. But i probably misunderstood his post or interpreted it wrongly.

Anyway, yes, in the case you describe, slats definately help rolling and are in case of the 109 (lacking washout) a requirement for controllability at critically low speeds / high AoA.

So yes, the slats help, when they come out. Wether or not they are an advantage compared to washout or similar design features of a plane, regarding roll "performance", is a different thing though.

[bugmenot]

Originally Posted by 5./JG27.Farber

Well if we are using anecdotal and pilot accounts lets throw these into the fire:

http://www.virtualpilots.fi/feature/articles/109myths/

I stongley urge the red fliers especially to read this. Its a shed load of pilot accounts with sources, all about the 109 and what an Uber plane she really is!





I found this:

http://www.rolfwolf.de/daten/E4/Emil.html



I assume these are full throttle speeds.

Höchstgeschwindigkeiten in Steig/Kampfleistung (Tabelle)
I assume this is TAS

0km 460km/h

1km 480km/h

2km 500km/h

3km 520km/h

4km 540km/h

5km 555km/h

6km 555km/h

7km 550km/h

http://www.rolfwolf.de/daten/E4/Emil.html


Leistungen

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m





Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

[5./JG27.Farber]

Originally Posted by bugmenot

http://www.rolfwolf.de/daten/E4/Emil.html


Leistungen

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m





Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

I cant tell what your trying to say? - Just to add a graph? Mein Deutsch ist Scheiße