Re: Dev. Report 138 - VDM-propeller: Some historical files

[Case]

First file is "Fluguntersuchungen zur Bestimmung von Luftschraubenprofil-beiwerten durch Impulsmessung im Schraubenstrahl" (my translation: "In-Flight-research for determining airscrew-profile coefficients through momentum-measurement in the propeller wash")

 

by E. Eujen and K.Sölf

 

Research Institute: Aerodynamische Versuchsanstalt Göttingen e.V. (Institut für Forschungsflugbetrieb und Flugwesen) (the 'AVA' as it's often abbreviated)

 

Test-bed was a He 70 with an (unspecified model of a) VDM-airscrew.

 

Source: Is the Central Archive of the DLR, the German Society for Aviation and Space: https://dlr-archivkatalog.bsz-bw.de/cgi-bin/koha/opac-detail.pl?biblionumber=19528 as the legal successor of the AVA.

AK-2290.pdf

Edited November 29, 2016 by Case

[Case]

Second file is "Landemessungen an einer FW 190 mit Anwendung der Luftschraube als Bremse" by one J Stüper and M. Seeger, again from the "Aerodynamische Versuchsanstalt Göttingen (AVA)"

 

Source: Again the archive of the DLR: https://dlr-archivkatalog.bsz-bw.de/cgi-bin/koha/opac-detail.pl?biblionumber=19330 ( AK-2248.pdf)

 

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And third file is "Messtechnik bei Flugversuchen Mappe  Goettingen"  - and again those are documents from the AVA, but it seems a "misc folder" that someone found in somebodies attic. This one includes a test of five airscrews, three of them different models of VDM-props.

 

Source:  "DeutscheLufwaffe.de" (a private online-repository)

 

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Note: During literature-research, I got the Impression that the "Aerodynamische Versuchsanstalt Göttingen" was pretty much the center of Aearodynamics research in Germany, and research on airscrews especially. They had a dedicated airscrew test-lab and were very proud of it. In the early 20th century, the AVA was led by one Wolfgang Prandl, who seems to have be some Aerodynamics-Hotshot.

 

There was a series of monographies on the aerodynamics research in the Kaiserreich and the 3rd Reich, the "Monographien über die Fortschritte der deutschen Luftfahrtforschung (seit 1939)". Especially Monographie H seems interesting regarding the VDM-propellers, since it was dedicated ... well, to airscrews:

 

• Monographie H 1: G. Tietz: "Theorie der Luftschraube für den normalen Arbeitsbereich"
• Monographie H 2.1: J. Stüper: "Messungen von Schub- und Leistungsbeiwerten an der Gesamtluftschraube"
• Monographie H 2.2: E. Eujen, K. Solf: "Messungen von Schub- und Leistungsbeiwerten am Schraubenelement (Impulsmethode)
• Monographie H 3: I. Ginzel: "Einfluss der Kompressibilität auf das Verhalten der Luftschraube"
• Monographie H 4.1: I. Ginzel: "Die Luftschraube am Stand"
• Monographie H 4.2: I. Ginzel: "Die schräg angeblasene Luftschraube"
• Monographie H 4.3: I. Ginzel: "Die gegenläufige Luftschraube"
• Monographie H 4.4: I. Ginzel: "Die Breitblattschraube"
• Monographie H 4.5: J. Stüper: "Die Luftschraube als Bremse"
• Monographie H 4.6: J. Stüper: "Die Reibungsschicht der Luftschraube"
• Monographie H 4.7: J. Stüper: "Verstellmomente von Luftschrauben"

It might be well worthwhile to obtain that "Monography H" - but sadly, the DLR archive fails us here: While it is listed as digitized, I couldn't find a link to the .pdf.

 

Contact details to the archive-admins are herehttp://www.dlr.de/zb/desktopdefault.aspx/tabid-8232/14127_read-36319/.

 

Note that many of those old files are "Präsenzbestand" - you have to personally go there & make copies, you can't take them out.

 

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Lastly: Though even German sources tend to refer to 'the' VDM-propeller, there are many variants with different blade shapes, etc., marked by a numerical code like "VDM 91xxxx.10". I think someone here has posted a copy of a field-manual that detailed the respective variants for Bf-109 and Fw 190.

Edited November 29, 2016 by Case

[=EXPEND=Tripwire]

Thanks for putting the effort in to locate this information Case.

[Holtzauge]

Thanks for putting the effort in to locate this information Case.

+1

[II/JG17_HerrMurf]

Have you also submitted them by PM to Han?

[Case]

Have you also submitted them by PM to Han?

 

 

I sent them to Dev-team and they are aware of them. Now we'll have to see whether the files contain helpful information, or whether further digging is necessary.

 

I could definately help with German/English translation, if necessary.

 

If further papers are needed ANDIF we 'know' they are located in the cental archive of the DLR in Göttingen, then I guess one of the German community who lives close to Göttingen could, in principle, make an appointment, drive there and make a copy of the print-versions.

 

Problem is: It's an archive that goes back to the 19th century, covering the work of many different Institutions - and only a small fraction is digitized, so we'd have to have a pretty good idea in advance where the information that we need is located. Browsing one or two books - that's standard literature-search that every student has done at some point. Browsing an entire Library however ...

Edited November 30, 2016 by Case

[-WILD-AlbinoHA5E]

OMG, Bf109 will be so OP.

[Dr_Molem]

OMG, Bf109 will be so OP.

 

?

[-WILD-AlbinoHA5E]

?

Arguably the best WWII Prop/Engine Combination finally being modelled correctly.

[SJ_Butcher]

Arguably the best WWII Prop/Engine Combination finally being modelled correctly.

 

OP or not we are looking accuracy after all, not balance from an arcadish game, if the plane was soo brutal then model it soo brutal too 

[E69_geramos109]

Thanks for the research. I have no idea of german language

[Crump]

Fluguntersuchungen zur Bestimmung von Luftschraubenprofil-beiwerten durch Impulsmessung im Schraubenstrahl"

 

Is momentum theory analysis of the He-70 propeller.  Nothing at all applicable to the FW-190A series and I hope they do not model its propeller based on this data.  That would be a fundamental error and akin to trying to determine the P-51 Hamilton Standard propeller characteristics by using data from a Cessna 172.

 

It does show that VDM was aware of the latest in propeller theory of the day and was on par with every other major propeller engineering firm in the world at that time.

 

 

 

"Landemessungen an einer FW 190 mit Anwendung der Luftschraube als Bremse"

 

Discusses the FW-190V-15 which was a prototype test bed for the DB-603A1 engine.  Nothing at all to do with an FW-190A series and would be another fundamental error if the FW-190A VDM data was confused with this stuff.

 

Does give good insight to the fact that VDM was a world class propeller engineering firm.

 

 

 

And third file is "Messtechnik bei Flugversuchen Mappe  Goettingen" 

 

Once again, nothing applicable to the FW-190.  This is different engine combinations and propeller designs from VDM.  Simply shows once again, VDM was a world class propeller engineering firm.

 

The FW-190 did use 5 different designs over its entire design life span.  I highly encourage you to continue your research and applaud your efforts.

 

To help the search here are the ONLY VDM propellers whose data is applicable.  Without careful consideration of the information posted....we will end up with another "Chalais-Meudon" polar incident, LOL. 

 

 

I have posted some propeller efficiency measurements for the VDM propellers used on the FW-190A comparing the change in climb rate as well as efficiency in the climb condition at 1.32ata @ 2400U/min.

Edited December 2, 2016 by Crump

[Holtzauge]

Case, don't be put off by any negative feedback: Science is about collecting data using it to improve your understanding of a subject and I for one appreciate your efforts and that you posted the data. Keep it coming!

 

If you could dig it up in the archives, what would be good input is propeller efficiency as a function of advance ratio (J) and propeller disc loading (Cp) for variable pitch propellers. If you have that then that is very useful to predict both climb and high speed propeller efficiency which can be quite different depending on how the propeller has been optimized.

 

A good example of the type of data on German propellers that would be good to find is something similar to this NACA report on the propeller efficiency of the P-47 Thunderbolt.

[Crump]

I would think the community would appreciate knowing what is important and what is not....

 

In fact, finding the thrust horsepower charts would be wonderful.

 

Here is the Jumo 213A Thrust Horsepower Charts used by Focke Wulf on the FW-190D9.  Thrust horsepower is the actual power produced by the engine based on amount of thrust the propeller actually imparts on the air.  The very definition of propeller efficiency is amount of shaft horsepower that is converted to thrust horsepower.

 

 

It is a direct measurement of the propeller efficiency and answers all the devs questions about the VDM propeller in terms of aircraft performance.

 

Here we have shaft horsepower chart for the Jumo 213A:

 

 

Here we have a Thrust Horsepower chart for the Jumo 213A.  In the corner you can see the formula is the Shaft Horsepower*Prop Efficiency* Standard Means of Evaluation(sqr root of the density ratio).  That gives up all the information required to construct the propellers efficiency.

 

 

 

So, for our FW-190D9 traveling at sea level at 1.8ATA@3250U/min at Vmax (608kph) we can see that:

 

Thrust Horsepower = 1850PS

 

Shaft Horsepower equals = 2100PS

 

Np = 1750/2100 = 88% propeller efficiency

 

Which is about average for a CSP propeller in level flight at sea level under standard conditions.

Edited December 2, 2016 by Crump

[=EXPEND=Tripwire]

My understanding from the DD was they were chasing information regarding the 109 prop due to what I assume was concerns some have had with its efficiency at low speed (prop hanging).

 

I'm sure the 190 information would no doubt also be beneficial though.

[Crump]

The FW190 was just for comparison but my understanding was they just needed information on the VDM propellers in general for the game aircraft.

[Holtzauge]

It is not negative feedback and certainly not meant to diminish the efforts.  In fact, I have to wonder why you did not help the guy out in the first place.  It seems very disingenuous to not help especially given your supposed background in aeronautical science.  

 

What do you think is the point of having folks "research" by looking for a needle in a haystack wasting their efforts uncovering useless information?  That does not do him or the community any good at all.  More people uncovering information is a good thing but not all information is good information.

 

My question is why did you as someone who should know better not offer to help the guy out and point him in the right direction so he does not waste his time?   

 

The answer to your question if this is useful information and if Case is wasting his time or not can be found in the number of community upvotes Crump: Just tally the number of upvotes Case got for his posts and the number of upvotes you got for your “analysis” and there’s your answer.

[Crump]

 

 

The answer to your question if this is useful information and if Case is wasting his time or not can be found in the number of community upvotes Crump: Just tally the number of upvotes Case got for his posts and the number of upvotes you got for your “analysis” and there’s your answer.

 

OMG....

 

That is your criteria...the number of upvotes?!

[Bearcat]

Yet another thread brought to an end by the usual suspects and their back and forth nonsense.