Originally posted by Knegel
You dont know for sure what is the reason for the different result, but you 1st was sure that the leverage is not the reason, but the linkage, then the geometry(leverage) did change cause a loose linkage.
There is no loose linkage, which have 15°/sec roll performence decreasement as result. A mechianic would call this damaged and i doubt that they made excessive test with a damaged plane.
We do know that the NACA tested Spitfire V had unlogical roll rate curve if compared to RAE and RAAF tested planes. We also know that the plane saw extensive flying in the US. It's my speculation that this is caused by loose linkage because at low speed and/or low aileron deflections reached values are normal. At high aileron deflection values differ considerably from the other tests and show characters which are not seen in other tests.
Originally posted by Knegel
I have enough education and experience in this field, its not a speculation!
I have no idea about your education or experience, but I can draw conclusions from your postings.
Originally posted by Knegel
Next to the strait line and the other line you clearly can read rate of roll, rate of roll get measured in degree/sec, not in degree/sec/degree.
No, let's have look:
First the text in the bottom: STEADY RATES OF ROLL PER UNIT AILERON ANGLE
Which means the steady rate of roll per degree aileron angle because the aileron angle is given in the degrees in the report. So it can be written:
(rate of roll)/(aileron angle)
Or with units:
(deg/s)/deg
Same is said with a bit other words in the left side of graph: STEADY RATE OF ROLL PER DEGREE AILERON (DEG.SEC^-1)
And same is said directly in the text: "
The variation of steady rate of roll per unit aileron angle with speed is shown in Fig.3"
Lets take an example: What steady rate of roll at 350 mph EAS can be reached with max available aileron deflection with 50 lbs stick force assuming flexible wing?
First we must take a look to stick force graph:
We can read from the stick force graph that at 359 mph EAS max aileron deflection is about 8 degrees with 50 lbs and at 308 mph EAS about 12 degrees so we can estimate that at 350 mph EAS we can reach roughly 8,8 deg aileron deflection. So now we can simply read from the Fig. 3 what kind rate of steady rate of roll per unit aileron angle can be reached at 350 mph EAS and the graph gives about 11 (deg/s)/deg for flexible (ie measured) wing so the rate of roll would be:
8,8deg x 11(deg/s)/deg = 96,8 deg/s
Note that unneeded degs "eat each other" and disapear
If we assume rigid wing, the Fig. 3 gives about 15 (deg/s)/deg and that results:
8,8deg x 15(deg/s)/deg = 132 deg/s
Now we know that if the roll rate curve gives about 97 deg/s at 350 mph EAS it contains wing twist and if it gives about 132 deg/s, the wing is assumed to be rigid. So let's have look to Fig. 6:
The chart gives about 97 deg/s so it contains wing twist. Lets look the NACA chart:
It gives the same value ie 97 deg/s so it contains wing twist too. Lets read what RAE 1231 says about the test data:
"
The best method of comparison of the rolling performance of different aircraft is based on the steady rate of roll a pilot can generate using a definite stick force, say 50 lb., or full aileron if this requires less than 50 lb. on the stick. This course has been adopted in Fig.6 which shows the results obtained for the F.W.190, Mustang, Typhoon, and Spitfire V (metal covered ailerons) with both standard and clipped wings. On all these aircraft instrumental records of rolling performance have been obtained at the R.A.E, similar to those under discussion for the Fw 190. In this connection it is worth noting that "instrumentation" is essential when obtaining the curves of Fig.6. Stop-watch measurements of time to bank on fighters are rarely of sufficient accuracy, since the times to be measured are so small."
So now we have 100% certainty that the RAE test data on the Fw 190, Spitfire, Mustang and Typhoon include wing twist. And the meaning of the grahs should be clear for all.
Originally posted by Knegel
The other NACA test also state clearly that the wing dont twist!
So it's says but RAE data proves that claim errorneous:
Note that again the steady rate of roll is given per degree aileron deflection just like in the wing twist graph of the Fw 190.
gripen
