Spit 14 turning circle

[Angus]

An aircraft that has increased wingloading will need some "X" increase in power to keep the SAME turning circle/radius.
AFAIK the Spit XIV had the same turning as the IX, however I do not know the alt/power curves or the alt during the test.

If my memory serves me the 109F could outturn the 109E by a margin while being heavier...Viking?

[Viking]

In my experience the 109F out-turns or is at least on par with the Emil in sustained turning. I don't know if there were any wartime test done to support this though. The 109F also has a slightly smaller wing area than the Emil.

[Angus]

It does? Always thought it was a tad larger due to the rounded tips.

[Viking]

Yeah, I thought so too until recently. They are in fact slightly smaller.

[Angus]

Did they chop of the chord or the span?

[gripen]

The original wing for the Bf 109F (as seen on the V24/V25) had rectangular tips and wing area 15,1m2. Later the wing area was increased to 16,05m2 in the production planes by attaching rounded wing tips to the 15,1m2 wing (there is also some other differences).

[Viking]

109E-4 wing area 16.17 m2

109F-4 wing area 16.10 m2


A very slight decrease in wing area.

[Krusty]

The wing area of the Emil was 16.17 square meters, but the area of the F and all standard later models (not counting odd-balls like the H) was 16.40 square meters.

EDIT: At least, I thought it was. Now I've got to check when I get home.

[gripen]

Well, there is some variance between the sources. Below is an original Mtt specsheet (source Jet&Prop 5/2001 p.8), the original F type wing (V24 and V25) was very close  the production F wing except the the rounded tips (+ some minor dimensional differences, differences in flaps etc.). Click picture to see the higher resolution image.

[Angus]

Originally posted by gripen
The original wing for the Bf 109F (as seen on the V24/V25) had rectangular tips and wing area 15,1m2. Later the wing area was increased to 16,05m2 in the production planes by attaching rounded wing tips to the 15,1m2 wing (there is also some other differences).

This is exactly what I thought.
Got to dive into my 109 books

[Krusty]

I don't think that's right. One Internet source (I know! I'm not saying it's right!) says the wingspan of the Emil is 8.76 meters and the wingspan of the 109F is 9.92 meters. That's over a full meter more. From what I thought, they used the same planform of the 109E and simply rounded it OUTSIDE of that planeform (meaning they tacked on more rather than taking off). This might support that idea.

That's what I thought. Could be wrong.

If the wing is essentially the same span, but one had rounded tips, then I can understand smaller area. However, if the rounded wingspan is significantly longer, even with a curved shape it should have more area.

Now the question is finding accurate numbers.

[gripen]

I don't know more relevant evidence than manufacturers drawings. The original F type wing as in the V24 and V25 had span of 8,89m, area 15,1m2, MAC at 1,78m, AR 5,22 and taper ratio 0,495 (values from Mtt report on V24 wind tunnel tests) so some writers might have confused E type wing with that.

[MiloMorai]

Originally posted by Krusty
I don't think that's right. One Internet source (I know! I'm not saying it's right!) says the wingspan of the Emil is 8.76 meters and the wingspan of the 109F is 9.92 meters. That's over a full meter more. From what I thought, they used the same planform of the 109E and simply rounded it OUTSIDE of that planeform (meaning they tacked on more rather than taking off). This might support that idea.

8.75m = 26.74ft

9.92m = 32.55ft

9.87m = 32.38ft

[MOSQ]

Originally posted by Urchin
I was playing around with the "Fighter comparison" website earlier, and I plugged in the Spit 14 vs the Spit 9.  Now, I have flown the Spit 14 a fair amount, and I actually like the plane, but it doesn't turn anywhere near as well as a Spit 9 does (in my subjective opinion).  

In real life, according to a test report I've seen linked several times here, the Spit 14s turning circle was reported to be "identical" to the Spit 9s.  This is in spite of the fact that it was 1,000 lbs heavier.  I guess the extra horsepower made up for the weight, in the test.  

The website (Fighter Comparison page ) agrees with my subjective assessment.  The smallest turning circle with flaps down is 509 feet for the Spit 14, and 433 feet for the Spit 9.  With flaps UP, the circles are nearly identical, with the Spit 14 having an edge that may or may not really be there (I'd say that difference is probably well within the margin of error for the data collection).  

I don't understand why the turning circles are identical with flaps up (which matches the test report), but drastically different (15%) with flaps down.  The wing and flap design didn't change between versions.

A different way to look at it is to compare turning circle size with flaps up to that with flaps down.  

The Spit 5 is 503 / 386 (~23% smaller).
The Spit 9 is 632 / 433 (~32% smaller).
The Spit 16 is 567 / 450 (~21% smaller).
The Spit 14 is 629 / 509 (~19% smaller).

Do the flaps on the Spit 9 just work exceptionally well?

Hi Urchin,

Since I did the testing for the data on the site you referenced I'd like to throw in a couple of comments about the data.

You are correct, the website has the wrong data on the full flaps radius for the Spits. The last testing I did was on 11-18-06 with Ver 2.09.1 . Here's what my spreadsheet says for the Spits:

Spit 1 is 471 / 395
Spit 5 is 502 / 434
Spit 16 is 567 / 460
Spit 8 is 568 / 476
Spit 9 is 632 / 528
Spit 14 is 629 / 538

The data used must be from an older test series or it got screwed up importing it into the web engine. So the answer to your question is with correct data, no, the Spit 9 flaps don't work exceptionally well! Thanks for pointing out the mistake. I'll see if we can get the correct data posted up.

In case you are wondering how fuel load affects turn radius:

Spit 16 25% fuel is 567 / 460
Spit 16 50% fuel is 583 / 482
Spit 16 75% fuel is 590 / 495
Spit 16 99% fuel is 605 / 511

1) I did the best I could to be consistent in the testing, but it is by no stretch what I would call very accurate. The biggest problem was with judging airspeed during the turning circles.

2) These tests show how well I flew the planes, others will be better or worse than me. For instance WideWing can usually turn a smaller circle than I can. However the relative performance to each other we have found to be fairly consistent.

3) The data is a getting old now. The drag modeling has changed, therefore some planes may fly differently now than when I did the testing.

I haven't flown much the last 9 months so I doubt I'll get enthused to spend the time it will take to retest all the planes.

I have been thinking of sponsoring a "Beat MOSQ's Turn Radius" contest. I might post a thread asking folks to try to beat my Radius, if they do I'll update the data with their info and give them credit for it. However they will have to send in FILM to prove it!

[dtango]

Originally posted by dtango

Radius(turn) =
                             V^2
                       -------------------------------------
                        g x sqrt [ ((Cl / Cd) x (T / W))^2 - 1]

From other relationships we can replace V^2 with 2x(W/S) where S= wing area.  This gives us the following:

Radius(turn) =    
                         2 x (W/S)
                      ---------------------------------------
                         g x sqrt [ ((Cl / Cd) x (T / W))^2 - 1]

I need to make a correction.  Earlier in this thread I posted two sustained turn radius equations.  The 1st equation is valid.  

The 2nd equation with the 2 x (W/S) term in the numerator is incorrect.  I made a couple of errors in derivation.

Many thanks to Badboy for noticing something odd and also for helping me check my math on request.

Tango, XO
412th FS Braunco Mustangs