DVL data on Bf 109 roll rates

[gripen]

Originally posted by Nashwan
Do you mean the highest line on the chart,  the extrapolated one that peaks at 1.6 rad, about 90 degrees, doesn't take account of wing flexing?

The lines with greek character "xi" and m give the roll rate with given average aileron deflection and these include wing flexing. But also the aileron linkage had some elasticity and therefore the average aileron deflection decreased with given stick movement when the speed increased. The line with greek character "phi" and max gives calculated roll rate with max stick movement. The chart below gives an idea how the average aileron deflection decrease when the dynamic pressure increase.

gripen  

[justin_g]

Originally posted by gripen
If some body want's to make comparison with the NACA data, the speed should be converted to IAS and mph and stick force should be converted to 50 lbs.

I've made a guesstimate of where the line for 50lbs(22.7kg) stick force would lie, and overlaid it on the NACA graph. It's not "gospel", but ppl can get a basic idea of the 109's comparitive performance.

[Squire]

Looks about right, the Zero is going to be slow at high speeds, with the Fw190 being the fastest, and everybody else somewhere in between.

[gripen]

Originally posted by justin_g
I've made a guesstimate of where the line for 50lbs(22.7kg) stick force would lie, and overlaid it on the NACA graph. It's not "gospel", but ppl can get a basic idea of the 109's comparitive performance.

As noted above you should use the line for max stick deflection. In my own calculations I have used peak roll rate 85 deg/s at 500 km/h TAS for the G but it's more like a compromise based on this and other data (all data contain some oddities including this). At 400 mph IAS the Bf 109F should roll a bit over 20 deg/s with 50 lbs stick force.

gripen

[MiloMorai]

So above 330mph IAS the normal span Spit rolls better than the 109 and the clipped wing Spit has a MUCH greater rollrate than the 109.

Am I reading the graph correctly?

[Charge]

"The question is, were those Bf109s in good enough condition to make the tests valid?"

I've never heard that 109s demanded anything special to keep up their roll rate as 190s did, so I'd imagine that they were OK to be used as comparison for roll rate???


-C+

[MANDO]

These numbers represent maximum roll rate, but not roll acceleration. Time from 0 to 180 degrees per speed applying # lbs starting from a no-roll state would be much more useful, as well as the same but starting with an opposite roll movement.

[Karnak]

Originally posted by MANDO
These numbers represent maximum roll rate, but not roll acceleration. Time from 0 to 180 degrees per speed applying # lbs starting from a no-roll state would be much more useful, as well as the same but starting with an opposite roll movement.

That is true, but I can't think of any such charts that I have seen.

The test pilots would have hated the test programs and performance documentation that we flight simmers would have had them do.

[gripen]

Originally posted by MANDO
These numbers represent maximum roll rate, but not roll acceleration. Time from 0 to 180 degrees per speed applying # lbs starting from a no-roll state would be much more useful, as well as the same but starting with an opposite roll movement.

Something like below?

gripen

[niklas]

Originally posted by MANDO
Time from 0 to 180 degrees per speed applying # lbs starting from a no-roll state would be much more useful

Any kind of this data out there for P47 , P51, oh and P38 of course?

niklas

[Knegel]

Hi,

here is a nice page for documents!

http://mitglied.lycos.de/luftwaffe1/

There is also a SpitVa test, with metal covered alerons!



According to this test the Spitfire dont got close to the 105°/sec, shown in the document above, at least not with 50lb, this would need around 70lb.

Unfortunately they show as max entry the 1.2rad/sec line, but it looks like with 50lb, the max rad/sec would be at around 230mph, while rooling to the right side. I estimate around1.4rad/sec. While rolling to the left side the peak is at around 190mph and max rollratio must be still around 1.4rad/sec.

Greetings, Knegel

[Karnak]

If it was a Spit Va it should have had fabric ailerons as they were all very early Mk Vs. It is possible it was being used as a test bed though.  I'll see what I can dig up about that when I get home.

[Nashwan]

I believe the NACA test is of a Spit V with metal ailerons. Guppy posted some info about it here some time ago

originally posted by Guppy35
This is the NACA tested Spit Va W3119 a very early Spit V with the external armored windscreen, flat canopy etc.

For anyone who has read Robert Stanford Tuck's biography "Fly for your Life" By Larry Forrester, this is also the Spit that Tuck did his little airshow at Wright field with.

To quote from the book "It happened that Wright Field had the only Spitfire in America-a Mark V. Unfortunately almost every pilot in the Air Corps had had a go on her and like a car that had too many drivers, she was the worse for wear...'She was very tired, very sloppy-she'd had the guts caned out of her all right.'"

W3119 was at Wright Field first in April of 41 and NACA saw her in July of 41.

With Stanford Tuck describing W3119 as "tired and very sloppy" while at Wright Field, you have to wonder how she was when NACA had her after this.

Now the Tuck biography has some errors too, such as mentioning Mustangs being tested with Merlin engines at Wright at the same time. While the Mustang I was around, the first Merlin conversion wasn't until October 42 in England, but it's a direct quote of Tuck on the condition of that Spit when he flew it so take it for what it's worth

http://www.hitechcreations.com/forums/showthread.php?s=&threadid=109977&highlight=caned

[Knegel]

Hi,

its with metal alerons!



This results are better than what i have for teh SpitI+II!

Greetings, Knegel

[Kurfürst]

Originally posted by gripen
The lines with greek character "xi" and m give the roll rate with given average aileron deflection and these include wing flexing. But also the aileron linkage had some elasticity and therefore the average aileron deflection decreased with given stick movement when the speed increased.

[/B]

Aileron linkage was done with metal rods, not cables like on the Spitfire, there was no 'linkage elastacy'.