Spit/109 sea level speed comparisons in 1.08 beta patch

[NZtyphoon]

Originally Posted by Crumpp

I got the weights from several flight test but did not have a ladeplan. The weight I used leaves out the pilot.

I fixed it and it narrows the gap but does not eliminate it.



The RAE chart uses CLmax neither airplane can attain in clean configuration by any calculation or measurement, including the RAE's. Read the report you claim I have not!

In fact, the CLmax comes very close to matching full flaps for both aircraft.

So while Crumpp is prepared to say that maths has all the answers compromises, such as leaving out the pilot and reducing the weight of an aircraft is okay - especially if it favours one type in particular over another. "I fixed it and it narrows the gap" but no explanation as to how this was done. Instead we are told to have faith in Crumpp's genius because he knows better than everyone else, as per usual.

[bongodriver]

Originally Posted by NZtyphoon

So while Crumpp is prepared to say that maths has all the answers compromises, such as leaving out the pilot and reducing the weight of an aircraft is okay - especially if it favours one type in particular over another. "I fixed it and it narrows the gap" but no explanation as to how this was done. Instead we are told to have faith in Crumpp's genius because he knows better than everyone else, as per usual.

Yep, one of the main flaws of Crumpps beloved maths, put garbage in and get more garbage back.

[IvanK]

Originally Posted by Crumpp

The RAE shows better turn radius in this chart. The Spitfire always has a better turn radius than the Bf-109.

Radius being just one parameter of turn performance and not the most important either.



Not specifically. It appears to be RAM power because the chart list's power in flight.



Exactly, once the parameters are input, the math does it's magic.

Er the chart above also shows Sustained G for any given IAS....at pretty much any IAS the Spitfire can sustain somewhere around 0.5G more than the BF109 ..... (not hard to determine turn rate here either)

The Blue RAE chart (from the same document) also shows sustained G, Turn times for 360 and also provides a means to determine Ps for bleeding turns ..... So we have turn radius, turn rate, sustained G (Ps=0) and a means to determine -Ve Ps values for energy bleed .... what more is there to turn performance ...... give us a break !

So far you have admitted to a weight error in your calculation. We know you made an error on the Spitfire power as well using 950/990BHP whilst RAE used 1050Hp at 12,500ft .... and we also know that a Merlin II power rating at Combat power was 1030hp at 16,500ft as detailed in the 2 seperate Inspection and test certificates.... shown earlier. And in Post 209 with respect Spitfire BHP you said "I suspect it was for an improved high altitude version".... when we know it wasn't and that RAE used standard Combat Power ratings.

[pstyle]

Originally Posted by Crumpp

They are not at the same speed or angle of bank!

Are you saying that, because we don;t know the AoB, we cannot therefore assume that their rotational velocity is equivalent - because the air passing over the indicator would not be equally displaced with respect to each aircraft's flight path?

If so, then yes, you're right I suppose.
Rotational velocity is dependant on more that simply airspeed and turn radius.. it needs "ground speed", essentially - which is the "real" speed around the spatial unit that is the turn.
Can we make any assumptions about likely AoB? The graph indicates that the turn is level (horizontally in each case). Do we know what the AoB differential is likely to be for each aircraft in each case? (then we can work out the proportion of airspeed that is in the horizontal plane).

[IvanK]

Now lets look at this Clmax discussion which Crumpp claims the RAE cocked up. Lets look at some other peoples estimates for Spitfire Clmax values.

How about we start with NACA ... we will use that very same report Crumpp that you are so smitten with that you used in setting up the "Spitfire Dangerous Stability thread". Here is NACA's estimate on Clmax



So at Cruise power (3.75lbs boost 2650RPM) in clean configuration they come up with 1.68 (Recalling that the RAE plot is based on +6.25Lbs/3000RPM)


Then lets look at the RAE document they wrote in response to the NACA report:



Interestingly the RAE methodolgy is slightly different to NACA's (Trailing versus Pole with swivel head) the RAE came up with Clmax on the glide (power off) of 1.36 and at max power of 1.89. The RAE Blue Turn plot uses a Clmax value under full power of 1.87

Of course we know the NACA report was based on a Spitfire MKVA so there will be some variance to the numbers of a Spitfire MKI but it does give some validation of the RAE determined Clmax under power values.

The NACA Spitfire MKVA document was good enough for you Crumpp in the stability argument regarding the MKI so I assume its an acceptable reference in this discussion ?

[Crumpp]

Pstyle says:
Are you saying that, because we don;t know the AoB, we cannot therefore assume that their rotational velocity is equivalent

That is correct.

IvanK says:
Now lets look at this Clmax discussion which Crumpp claims the RAE cocked up.

Why don't you do the math IvanK? You have a better idea of how to interpret aircraft data. That is not being patronizing, it is just a fact. You can set emotion aside and let numbers fall where they may....

If you do the math, you will find the values for CLmax align with the NACA's!!

Spitfire Mk I:

Speeds Dynamic pressure CL
66 14.76610169 1.693067034




Once more, the RAE admits that operating a trailing static head is difficult as best. Do you know what you have to do? When installed, you have a tangle of tubes in the cockpit that the pilot must pinch off with an airtight seal on the correct lines at the right time. It is hard enough in cruise flight and would be extremely difficult to do accurately in a high performance fighter at the stall point.

That is why they labeled the values as "assumed values of CLmax".

[Crumpp]

IvanK says:
RAE methodolgy is slightly different to NACA's

Because of the difficulty in obtaining accurate measurements under certain conditions of flight.....

See above.

Glad you brought up all these points. You read my mind. .

You can use the NACA's values for some things on the Spitfire Mk V. The airfoil is the same. Airfoil selection is what determines Coefficient of lift.

If I would have posted it, some people would have just attacked it was from a different variant without understanding what is comparible and what is not.

[ATAG_Dutch]

Let me guess here.

The 'math' (or 'maths' as it's referred to over here) according to Crummp, shows something adverse to the documented real life performance of the Supermarine Spitfire relative to the performance of the Bf109.

There is a distinct pattern developing here.

I find it surprising that a man who purports to concern himself with the performance of 'real aircraft', does not spend his time debating these issues on a more appropriate forum involving comparisons between 'real world' aircraft.

Why would such an expert in his field waste his time on a forum geared to the analysis of a Battle of Britain based computer game? With most of his efforts geared toward the discrediting of the Supermarine Spitfire relative to the Messerschmidt Bf109?

It's a mystery to me, but maybe a psychologist could write a thesis.

[Crumpp]

shows something adverse to the documented real life performance

It is not documented real life performance.....

It is calculated from a single data point with assumed values for CLmax.

That single data point was measured from a trailing static head.

What do you think the spreadsheet is??? Try the same the exact thing...calculated performance from data.

I just have the advantage of being able to use Mtt data, Supermarine, and NACA data that did not exist in 1940.

[Kurfürst]

Originally Posted by NZtyphoon

So while Crumpp is prepared to say that maths has all the answers compromises, such as leaving out the pilot and reducing the weight of an aircraft is okay - especially if it favours one type in particular over another.

Uhm, the weight Crumpp used for the Spitfire I doesn't include the weight of armor either. So how this - marginal - weight difference favours one type over the other, Sherlock?

"I fixed it and it narrows the gap" but no explanation as to how this was done. Instead we are told to have faith in Crumpp's genius because he knows better than everyone else, as per usual.

I see. Crumpp understands the formulae behind calculating turn radii and time, you do not, and somehow he is to be blamed for your ignorance? Or maybe it is his fault that after your never ceasing personal attacks, he is not particularly inclined to bother to explain it to you?