109 it fly wrong

[mw]

Hello Hohun: good, the charts are clear enough.  The following taken from the 3 German level speed curves should be interesting then:

Sea level speed
315 mph
316 mph
315 mph

“First Stage”
350 mph at 8,220 ft.
352 mph at 8,220 ft.
353 mph at 8,530 ft.

FTH
388 mph at 20,013 ft.
385 mph at 21,982 ft.
391 mph at 21,653 ft.

32,808 Ft.
364 mph
360 mph
360 mph

Looking at the level speed curves its apparent that the performance of the trials aircraft are within 5 mph throughout most of the flight envelope.  That’s pretty darn good.

MT-215’s performance  runs a bit stronger on average, by more than 5 mph up to FTH where it falls off.

Given the above data, the Russian data showing 670 km/h @ 7000 is not credible.  Your acceptance and priortization of this data set, combined with your rejection of the documented german trials climb performance at 1.3/2600, points towards a need to refine your assumptions of the 109s aerodynamic efficiency.

It could be seen as a bit odd that you place such weight on Russian trials, of which the engine limits,  aircraft configuration, and test parameters are unknown, when there is perfectly good German trials data available.  It would also seem difficult for a spreadsheet model to allow a good fit for both the Russian and German curves.

Are you trying to calculate a theoretical, idealized 109G?  Actually, I suspect your model might fit the German trials data  reasonably well,  give that a try.  Use, for example, the German FTH average of 388 mph at 20,893 as your calibration point and see  if your model generates 315 mph at Sea level.  If so, then perhaps you are on to something.

I can see where reconciling the engine curves with performance trials could be useful in fabricating a model that could generate rough estimates.  It’s a fine thing, and no doubt enjoyable for you to construct your estimates.  I only take exception when you present them as fact.  My apologies in advance if I’ve misconstrued your position.  I’ve not had the time, nor sufficient interest  in calculated estimates frankly, to give the thread my full attention.

[VO101_Isegrim]

Originally posted by mw


MT-215’s performance  runs a bit stronger on average, by more than 5 mph up to FTH where it falls off.

Given the above data, the Russian data showing 670 km/h @ 7000 is not credible.  Your acceptance and priortization of this data set, combined with your rejection of the documented german trials climb performance at 1.3/2600, points towards a need to refine your assumptions of the 109s aerodynamic efficiency.

Of course it`s 'not credible', Mike, how could it be,  : the results too good.

You deliberately choosed the worst figures you can find, for everyone that is crystal clear.

For the same reason the Finnish trials are ignored : first of all, even 640 km/h max. speed is too much for Mike, but even worse, there`s that damned Finnish climb chart, showing 4700 fpm climb rate. That`s on a 30min rating, not even at full power!
It wouldn`t fit into Mike`s agenda, and people would ask : 'Mike, you put the Finnish speed chart on, but why not the climb chart, too?'

But faster than a Spitfire? LOL, can`t happen in Miky boy`s head. Mustabe a cheat. In any case, hardly a problem, since the 109F-4 could already do 660-670 km/h, in other words, the 109 was already a good deal faster than any of the Spits variants a year later on in 1943, even when we ignore the fact how few of those Mk IXs actually saw service compared to the massess of old Mk Vs in 1943.

Like I said, the good fighters don`t need cheaters to help them out.

Regarding the Bf 109`s aerodynamic effiency, not much to discuss on it.  

The Bf 109G as according to the test could do apprx. 525 km/h at 1310 Ps, that would be something like 1285 BPH or so.

The Spit IX F at +15lbs and 1340 BHP at SL could do 502 km/h at SL.

Enuff said. Pitting the most successfull fighter of all times against an orthodoxly designed, all flying thing that never improved beyond the tech level of mid-30s aerodynamics isn`t really fair IMHO.

[VO101_Isegrim]

It could be seen as a bit odd that you place such weight on Russian trials, of which the engine limits, aircraft configuration, and test parameters are unknown, when there is perfectly good German trials data available.

Glad to hear you have problems with that Mike. Now, pray tell, what are the exact conditions of the planes you call as :

"109 Serie Versuch Nr. 10 18 105 428 Daimler Benz"

Now what on Earth that could be ?

Or this one,

"109 VB Nr.  109 20 L43, Messerscmitt AG"

What model, G-1, G-2, G-3, G-4, G-5, G-6, a G-8or a G-14, a G-10?

What is the serial number of the plane, what do the report say of the external conditions, condition of the surface, loading of the plane, what corrections were used, Miky?

No, you don`t know any of these parameters, NOT ONE OF THEM, still you don`t bother to list the plane as a representative of the Gustav, yet start crying about the NII VVS live trials done with a known Werknummer, captured plane at known power boosting (1.42ata).
How pathetic Mike, your double standards wearing thin.


Come up with an asnwer, Mike. I don`t expect that to happen, you will cowardly run away, back to your little hide where you can m@sturbate wet dreams further on how much the Spitty is 'totally superior' in 'every respect', well, with a little help from Miky himself with the goal to fool the ones who can be fooled - which may turn out it`s only one person who satisfies his own needs in this way..

Uhm, I hurt ya, Mike ? Sorry `bout that, you know, the truth is what hurts the most of all things.  

[MiloMorai]

Barbi, can you ever conduct yourself in a civil manner?

This is not one of your 'ambulance chaser' courtroom farces. The few Hungarians I have met are not as obnoxious and utterly ignorant as you are. Hopefully the other Hungarians are not cast in your mold. But, if one is a 'brown shirt' worshipper, your conduct is totally understandable, for sure.

The only one that with an agenda is you and that is to try to convince people that the Messicrap 109 was the best se fighter ever designed and built. Sorry Barbi, it had its good points and bad points like every other a/c ever built.

[HoHun]

Hi Dweeb,

>Have you tried the "trendline" option for curve fitting? It seems to work very well.

I purposefully used the solver with hand-crafted formulae because I wanted full awareness of what Excel is doing :-)

>PS, yes, I am a FSforum survivor from the late eighties, early nineties

Nice to meet you (again)! :-) Great place, home to a lot of friendly and knowledgable people back in those times!

Regards,

Henning (HoHun)

[HoHun]

Hi Mw,

>Given the above data, the Russian data showing 670 km/h @ 7000 is not credible.  

The discussion of Russian data can be found above in this thread.

>It would also seem difficult for a spreadsheet model to allow a good fit for both the Russian and German curves.

Actually, I get a satisfying fit for Russian and Finnish curves by merely using a different full throttle heights, along with the drag differences pointed out by several contributers.

>I only take exception when you present them as fact.  

Well, scientific analysis is the only universally accepted way of arriving at facts.

(Divine inspiration works quicker and more accurately, but I can't use that here because it's not universally accepted ;-)

Be aware, though, that (unlike divine inspiration) scientific analysis is a lengthy process. I'm far from a final analysis of Me 109G data - in fact, I've hardly begun yet.

Regards,

Henning (HoHun)

[butch2k]

Since i have some access to Russian archives, here is the 109G-2 data as tested by the russians.

Alt / Speed / RoC

0K / 524 / 19
1K / 554 / 20.2
2K / 582 / 21
3K / 602 / 18.9
4K / 608 / 17.5
5K / 610 / 16.6
6K / 640 / 15.9
7K / 666 / 13.2
8K / 660 / 10.6
9K / 648 / 8.0
10K / 624 / 5.3

Time to 5000m : 4.4m
Weight 3023 Kg
Power at SL : 1310 ch
Power at 5800m : 1300 ch (!!!)

As a side note the full report is 17 pages long.

[HoHun]

Hi Butch,

>Since i have some access to Russian archives, here is the 109G-2 data as tested by the russians.

Thanks! :-) That's a nice surprise! Am I correct that the tested aircraft was W.-Nr. 14513 as I suggested earlier in this thread?

>Power at 5800m : 1300 ch (!!!)

Ah, there we have an important part of the explanation why the Russian aircraft was so fast. The standard engine would have just 1250 HP at full throttle height. (Low altitude power is almost on specification, though.)

The corrected figure for the Russian Bf 109G-2 with a 7 km full throttle height would be 657 km/h.

Is there any hint in the report how the 7 km full throttle height was possible?

(Did the Russian aircraft feature the retracted tail wheel? It certainly had a better drag condition than the Finnish aircraft.)

Regards,

Henning (HoHun)

[mw]

Hiyas, I had a hunch the Russians increased the RPMs above a certain height.  Would that explain the FTH and speed?

[HoHun]

Hi Mw,

>Hiyas, I had a hunch the Russians increased the RPMs above a certain height.  Would that explain the FTH and speed?

Good suggestion! :-) A similar technique was later used with the Bf 109K-4, so we should check that out. The RAE also tested their Emil that way, which is another precedence.

Hopefully, Butch's document will have the details so we can know for sure.

Regards,

Henning (HoHun)

[butch2k]

i have for 2600rpm:
1310hp@SL
1390@2300m
1300@5800

As for the aircraft tested, there are two of them : 13903 for the Cannonboat and 14513 for the regular version.
13903 achieving 650@7000m with gunpods @ 3235kg

Haven't got my way through the most cryptic parts of the report yet, but i believe that indeed tail wheel was retractable on both.

[VO101_Isegrim]

Originally posted by HoHun

>Power at 5800m : 1300 ch (!!!)

Ah, there we have an important part of the explanation why the Russian aircraft was so fast. The standard engine would have just 1250 HP at full throttle height. (Low altitude power is almost on specification, though.)

I assume you simply took the static 1.3ata output at 5.8km and moved it to 7km to arrive at this, but that wouldn`t be 100% accurate, as the lower heat means also higher effiency of the s/charger at higher altitudes - just look at rammed speed figures, ie. I have those for the 601N, these show 1190 PS at 5.5km in static position, but when rammed this grows to 1230 PS at 1200 kg/m2 'Staudruck' !

So it isn`t just the same power at a higher altitude.

The corrected figure for the Russian Bf 109G-2 with a 7 km full throttle height would be 657 km/h.

I don`t think there`s need to 'correct' those figures any more.

Is there any hint in the report how the 7 km full throttle height was possible?

(Did the Russian aircraft feature the retracted tail wheel? It certainly had a better drag condition than the Finnish aircraft.)

I suppose the clean (as factory standard) config is the key. As mentioned, (now that we know that the tailwheel on the Soviet plane was retractable) lower drag would mean higher achievable speeds, which mean more ram gain, and a result, higher critical altitude that on the other planes that were all flown with non-retractable landing gears.

By default, the G-2/G-4s tailwheel was retractable, unless it was late production model with the larger tailwheel.

Good suggestion! :-) A similar technique was later used with the Bf 109K-4, so we should check that out. The RAE also tested their Emil that way, which is another precedence.

I don`t think there`s RPM increase. Why would there be? Personally I think this new idea is only supposed to replace the "unknown conditions, thus ignore, ignore!" line after it crumbled.

Speaking of the 109K`s RPM increase at altitude, surely the climb/speed charts show it, but I am not sure of it`s true nature, wheter it`s something automatically happening above a certain altitude, or is it simply a case that over the FTH, the RPM can be manually increased by advancing the throttle further than 100% to reach to same 1.45ata Kampfleistung boost at 2800 rpm`s increased supercharger speed (at 2600rpm supercharging would be inaduquate to maintain that boost any longer)... I tend to believe the latter, but it`s just a guess.

[VooDoo]

http://www.x-plane.org/users/hohun/me109g-2.jpg

That P-40 at 57" - is that calculated figures or realtest data ?

[gripen]

Originally posted by HoHun
Hi Isegrim,

>Yep, Werknr. 14026 in the DB601E/DB605A swapped engines test did 586 km/h at 10000m

Rather funny! :-)

That's exactly the value I predicted for the FAF aircraft, and which Gripen found so impossible to believe that he accused me of data manipulation and forgery.

Here HoHun forgets to told that his calculated value 586km/h is for engine running at 2540rpm and tail wheel down. And he also forgets to told that the data he used was really manipulated  (the evidence is above) and made his new curve to start from 200m higher than value in the FAF chart (which allready was 20km/h too high).

My estimate for MT-215 running 2600rpm and tailwheel in was 578km/h at 10000m.

gripen

[HoHun]

Hi Voodoo,

>That P-40 at 57" - is that calculated figures or realtest data ?

Calculated :-) However, I'm entirely confident it's more representative for a real P-40N-1 than any particular set of real test data.

(In fact, it's very close to one particular set of real test data where the engine didn't reach full boost at full throttle height. It appears a bit better than most P-40N-1 data around because it's based on a clean airframe with no bomb racks etc. However, it was cross-checked and confirmed by a real P-40N-5 data point for a very similar clean airframe. If you're interested in the 378 mph top speed sometimes quoted for the P-40N-1, that couldn't be confirmed, neither from real test data nor from calculations. I didn't personally do the research for the P-40, though, just the calculations that were used for the analysis of the raw data.)

The relation to the Me 109 analysis is that the P-40 and the Me 109 spreadsheets are the same. I simply entered new parameters and a new engine graph because I figured the laws of physics are just the same for both aircraft types :-)

Regards,

Henning (HoHun)