Official Fulqrum Publishing forum - Throwing some light on rates of turn

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- - Throwing some light on rates of turn (http://forum.fulqrumpublishing.com/showthread.php?t=32285)

Quote:

Originally Posted by Holtzauge (Post 432478)

Concerning Kurfurts post I'm not going to be drawn down to that level. Replying to that in an appropriate manner requires breaking the forum rules. Toddler tantrums require strict parenting and I leave that up to whomever it may concern.

So returning to the grownup discussion:

The additional data posted by IvanK now gives the engine power as well and the turn time at 20,000 ft can as MIG-3U points out be read out of that figure to be in then order of 30 s. In fact the same report contains an even more precise figure of radius 1045 ft, bank angle 51 degrees and turn time 31.5 s in table 4 on page 4.

While we are waiting for Crummps 21 s 68 degree bank proof here are some C++ simulation results showing the relative performance between the 1.3 ata Me109E and Spitfire Mk1 at +6.25 boost:

As expected the Spitfire is somewhat better at 20,000 ft due to the lower wing loading. However, the interesting thing is however that at low level (1 km) my simulations show that while the Spitfire turn better at low speeds, the Me109E turns better than the +6.25 boost Spitfire Mk1 at TAS speeds over 290 Km/h. However, if one assumes the +12 boost then it is of course no contest, either at low or higher speeds.

Hello Holtz,

Do you consider 109 slats in your simulation?

Yes, slats are in there implicitly but not modelled as such: I assume a power off low Mach Clmax of 1.45 and since the slats on the Me109 start to come out at around Cl=0.8 and IIRC are fully deployed at 1.2 they can be said to be modelled.

Quote:

To maintain given angle of bank at given KEAS, power must increase with altitude.

I know this very well MIG3.

If you look at the thread before my altitude conversion there is only one document from this report posted.

Page 16 is when IvanK posted one snippet from the report:
http://forum.1cpublishing.eu/showthr...=32285&page=16
Page 17 is when I showed Kurfurst how to convert performance to altitude from that snippet:
http://forum.1cpublishing.eu/showthr...=32285&page=17

Here it is the only information in the thread at the time I replied:

http://img823.imageshack.us/img823/3811/turnwitflap.jpg

There is not enough information to do any kind of detailed analysis.

None the less, I knew Holtzauge would be up to his old tricks again as soon as he posted. So I included the answer to specific performance in my very next reply.

Quote:

Crumpp says:

The specific numbers for rate and radius will change in proportion to density ratio which is a universal application.

http://forum.1cpublishing.eu/showpos...&postcount=170

But Mr Holtzauge ie Msc Aeroengineering blah blah blah did not understand.

There is no power information provided and the report is obviously discussing theory and not reality with the different degrees of flap. So when I answered Kurfurst question about how to change altitudes, there was nothing to convert in terms of power to get specific performance.

Holtzauge is not some engineer. He is an internet troll plain and simple.

Why do I know this?

I rather long history of dealing with him. Let's look at how to vary thrust production with altitude. This is from the old Ubizoo board. The discussion comes about because some folks cannot seem to line up power in terms of Equivalent Airspeed. They kept coming up with a load factor that was way too high when they used EAS. Why? They knew how to parrot some TAS formulation but did not understand the theory behind it. Therefore when they went to convert EAS back to TAS, they did not convert their power and ended up with much higher load factors.

A basic aircraft performance text, Perkins and Hage, "Aircraft Performance, Stability, and Control:
http://img10.imageshack.us/img10/708...epowerwith.png

Quote:

Crumpp says:

Lastly, for all the "experts"...

If we want to hold our assumptions the same then we need to vary thrust with density.

2300 hp * .85 = 1955thp

1955thp*325 / 180KEAS = 3529.861111lbs of drag

sigma = .53281 @ 20,000ft

SQRT(.53281)* 3529.861111lbs of drag = 2576.58lbs of drag

2300 hp * .85 = 1955thp

1955thp*325 / 246.6KTAS = 2576.5lbs of drag

http://forums.ubi.com/showthread.php...=1#post2939042

Holtzauge says:

Quote:

Just had a closer look at your calculation and it does seem you are in dire need of an “expert” to “demonstrate” aerodynamics to you :

You get confused by your own equations.

By definition, EAS means that you have the same dynamic pressure q at both altitudes. You don’t seem to have grasped this since you suddenly show 2576.5 lbs drag at 20000 ft and 3529.86111 lb at SL.

You see the drag will be the same at both altitudes, i.e 3529.86111 lb. Otherwise it’s not EAS.

So entering the correct drag into the thrust equation yields:

Ps hp * .85 = Pt thp

Pt thp*325 / 246.6KTAS = 3529.861111lbs of drag

So Pt=2678.35

Which gives Ps=2678.35/0.85=3151 hp

I guess you shot a really big hole in that foot now Polly. All the while you have been parroting on how important it is to use EAS and you can’t seem to be able to use it properly yourself…

http://forums.ubi.com/showthread.php...=1#post3177597

That is why I ignore the guy.

:cool:

Maybe this is one the lesson in aerodynamics at the IL-2 General Discussion Forum that Kurfurst was refering to earlier? The problem with that lesson was that you did not only loose me but also Wurkeri, JtD and FatCat_99 who did not understand that lecture either.

http://forums.ubi.com/showthread.php...soviet+fw-190a

One thing that escapes me is where you have hidden the proof for the 21 s turn time for the Spitfire Mk1 at 20,000 ft you claim? I can't see the forest for all the trees.

Can you point that passage out please?

Also: I notice you are back to calling me a troll and no engineer and claiming I have no Msc degree. The irrefutable proof for this seems to be that I don't agree with you right? Where is your resume?

How about staying on topic and nailing down the 21 s turn time proof instead?