Bf 109 H WNr.110073

[piero]

I am trying to reconstruct what was the most probable aspect of the only Bf109 H that went into action; by reading all the documentation in my possession, including the material of the following links:

Bf 109 H (page 1)

Bf 109 H in service with 5.(F)/123 - Luftwaffe and Allied Air Forces Discussion Forum and the attached document


https://www.flickr.com/photos/162245...posted-public/

https://www.flickr.com/photos/162245...posted-public/

I have developed the drawing you see.

https://www.flickr.com/photos/162245...posted-public/

I would be grateful for any suggestions and/or modifications you would like to suggest.

Many thanks in advance.
Giampiero

[pvanroy]

First off: many thanks for posting that Bauzustand for the Guyancourt 109 H - I had not seen that before!

Just a couple of thoughts:

- You indicate that the regular pressurized canopy was later replaced by an Erla Haube. On what information is this based? A pressurized version of the Erla Haube was developed, and prototyped, but I have never seen it installed on an actual airframe. If it was installed on the 109 H that would be really interesting.
- Since the aircraft was pressurized, there should be a small intake on the right side of the cowling for the compressor of the pressurization system (as on a regular G-5). As an aside, I have never seen images of an AS cowling with an intake for the cabin pressurization compressor.
- Since the machine was constructed on the basis of a standard G-5 converted to AS, it seems likely that it used the regular AS cowling. However, for the 109 H, a more refined cowling was planned, which ultimately saw use on the Erla produced G-10. So, it cannot be excluded entirely that the Guyancourt machine may have had the refined cowling.
- The Bauzustand report states that the radiators were positioned in the wing extension "as in the 109 H V55". According to some interpretations, the H V55 had the radiators incorporated into the leading edge of the wing extension.
- The Restabdeckungen for the main gear may not have been entirely like those of the K. Messerschmitt also designed Restabdeckungen for the G, but these were not introduced widely, although some individual machines were equipped with them (e.g. Graf's G-6). The Restabdeckungen for the G were metal, whereas those of the K were wood. Also, in the G they were actuated hydraulically, whereas in the K it was through a pulley system connected to the main gear retraction system. However, this would not really be visible in your drawings.
- Your side views show the aircraft with a regular 109 G wing (no extended tip, slats, ailerons or flaps).
- Two of the links in your post both lead to the same Bauzustand report.

Just my 2 cents!

[Nick Beale]

If it helps, this is the verbatim text of teleprint CX/MSS/T187/48 (TNA file HW5/484)

WEST EUROPE

TO TECHNICAL OFFICER, DATED 16/5:-

THE STAFFEL REPORTS SURRENDER OF BF 109 G-5, WORKS NO 1(B%1)0346, THROUGH SALVAGE DETACHMENT 20/IV ANVIEN(+) TO GUYANCOURT WORKSHOP ON 14/5. THE STAFFEL REPORTS ACCEPTANCE OF BF 109 H, WORKS NO. 110073 ON 16/5, FROM GUYANCOURT WORKSHOP. A/C HAS DB605-GS ENGINE MMM METHANOL INSTALLATION AND GM1- INSTALLATION, CAMERA 50/30, FU GE 16 Z, WITH HOMING ATTACHMENT ZVG 16, FA16E AND FA16S, PRESSURE CABIN, AND 1 MG 151-20.

NOTES: 1) SOURCE BELIEVES ABOVE FROM 5(F)123

2) (+) NOT LOCATED. MAY BE ANVIN, LOCATED IN PAS DE CALAIS AREA

3) AN ME 109 WITH H BUILT IN £H - EINBAU£ WAS READY TO BE COLLECTED FROM GUYANCOURT ON 10/5 (T182/3)

4) SEE T187/47 FOR TECHNICAL DEFECTS IN THE COMPRESSED AIR SUPPLY OF BF 109 G-5 (HIGH ALTITUDE A/C).

1752/17/5/44

[piero]

Originally Posted by pvanroy

First off: many thanks for posting that Bauzustand for the Guyancourt 109 H - I had not seen that before!

Just a couple of thoughts:

- You indicate that the regular pressurized canopy was later replaced by an Erla Haube. On what information is this based? A pressurized version of the Erla Haube was developed, and prototyped, but I have never seen it installed on an actual airframe. If it was installed on the 109 H that would be really interesting.
- Since the aircraft was pressurized, there should be a small intake on the right side of the cowling for the compressor of the pressurization system (as on a regular G-5). As an aside, I have never seen images of an AS cowling with an intake for the cabin pressurization compressor.
- Since the machine was constructed on the basis of a standard G-5 converted to AS, it seems likely that it used the regular AS cowling. However, for the 109 H, a more refined cowling was planned, which ultimately saw use on the Erla produced G-10. So, it cannot be excluded entirely that the Guyancourt machine may have had the refined cowling.
- The Bauzustand report states that the radiators were positioned in the wing extension "as in the 109 H V55". According to some interpretations, the H V55 had the radiators incorporated into the leading edge of the wing extension.
- The Restabdeckungen for the main gear may not have been entirely like those of the K. Messerschmitt also designed Restabdeckungen for the G, but these were not introduced widely, although some individual machines were equipped with them (e.g. Graf's G-6). The Restabdeckungen for the G were metal, whereas those of the K were wood. Also, in the G they were actuated hydraulically, whereas in the K it was through a pulley system connected to the main gear retraction system. However, this would not really be visible in your drawings.
- Your side views show the aircraft with a regular 109 G wing (no extended tip, slats, ailerons or flaps).
- Two of the links in your post both lead to the same Bauzustand report.

Just my 2 cents!

First of all, thank you for your articulate answer.
- regarding the Erla-Haube I invite you to read the first document, or the answer that Nick Beale gave immediately after you
- it seems, I say it seems, that there were Bf 109s pressurized both with that without the small intake on the right side of the cowling, in any case the refined cowling did not have it, at least in the production airplanes
- I think the radiators were positioned as on the V50 or V54
- I agree perfectly with you on the two different types of Restabdeckungen, I wrote 'K' to clarify the concept (I did not want to write too much on the drawing)
- you are also right on the side profiles, but you must know that the proposed drawing was not done by me (I absolutely do not know how to draw ), but it's a collage made with various other designs and I didn't find a good side view of the 'long wings'
- I fixed the links in the meantime.


Giampiero

[harrison987]

There are also quite a few well-known drawings on the web...

[pvanroy]

Many thanks for your reply! Just some comments:

- Erla Haube: unless I overlooked something, the Ghostbombers website only states "On 11 May, 5.(F)/123 had been told that 15 all-round vision canopies were ready for collection from the ERLA works airfield at Antwerp-Deurne: the Staffel was to keep three, the rest were for Guyancourt." So, they received Erla Hauben from Erla VII, but that does not necessarily mean one of those was used on the H conversion (for which it would have needed to be a pressurized version, which was quite significantly different in a number of aspects from the regular Vollsichthaube). Also, maybe again I overlooked it, but I don't see any mention of a Erla Haube in the transcript reproduced by Nick Beale here.

- Cabin pressurization intake: interesting if there were some that lacked this intake... I just wonder, in that case: where would the compressor get its air, if there was no intake? And weren't these Erla cowlings standardized - after all, there are lots of G-6 and G-14 without pressurization that do have the bump and intake even though on those aircraft it's not needed. In the case of G-5/AS conversions, I think there is some question as to whether those retained cabin pressurization after conversion - if not, they wouldn't have needed the intake on the refined cowling anyway.

- Radiators: I tend to agree, but on the other hand I do find it interesting the document specifically references the installation of the H V55, and not the V54.

Thanks for your efforts!

[Nick Beale]

Originally Posted by pvanroy

Many thanks for your reply! Just some comments:

- Erla Haube: unless I overlooked something, the Ghostbombers website only states "On 11 May, 5.(F)/123 had been told that 15 all-round vision canopies were ready for collection from the ERLA works airfield at Antwerp-Deurne: the Staffel was to keep three, the rest were for Guyancourt."

In the original:

CX/MSS/T181/124

Source copied document of 11/5:

With a view to fetching the 15 all-round vision cockpits for Bf 109 which have been allocated in accordance with communication of Lehr and Ersprobungskommando 24 Großenhain, the Staffel will immediately despatch a collecting detachment to the Erla Works, Airfield Antwerp-Deurne.
3 of them are intended for the Staffel and can be at once taken over. The remaining 12 are to be sent on to workshop at Guyancourt.

NOTE: Source has reason to think that 5.(F)/123 was the Staffel concerned.

Source: TNA file HW 5/481

[harrison987]

You cannot pressurize an Erla Haube.

The reason why is because of the tubular construction, and lack of seal at the BACK end of the canopy.

The construction was steel and mild steel. Mild steel was used all around the tubular construction (especially at the rear), and bent very easily (malleable with your hand). As such, there is no way to seal around the cockpit.

In addition, the only part of the 109 cockpit that was ready for pressurization was the cockpit tub (firewall to seat back).

The fuselage was not made pressurized behind the seat...and the Erla Haube extended all the way to the baggage compartment.

There would have had to be a complete re-deign of the entire cockpit to make that work...as well as a newly designed canopy and rear armour.

This is why the 3-piece canopy was only used on pressurized models...it sealed right at the seat back, where the head armor (newly-designed for the pressurized cockpit) enclosed the entire cockpit.

Soooooo...if it had an Erla Haube...it was not pressurized.

The only way it could have been pressurized, is if it had the 3-piece G3/G5 Canopy.

[pvanroy]

Originally Posted by harrison987

You cannot pressurize an Erla Haube.

The reason why is because of the tubular construction, and lack of seal at the BACK end of the canopy.

The construction was steel and mild steel. Mild steel was used all around the tubular construction (especially at the rear), and bent very easily (malleable with your hand). As such, there is no way to seal around the cockpit.

In addition, the only part of the 109 cockpit that was ready for pressurization was the cockpit tub (firewall to seat back).

The fuselage was not made pressurized behind the seat...and the Erla Haube extended all the way to the baggage compartment.

There would have had to be a complete re-deign of the entire cockpit to make that work...as well as a newly designed canopy and rear armour.

This is why the 3-piece canopy was only used on pressurized models...it sealed right at the seat back, where the head armor (newly-designed for the pressurized cockpit) enclosed the entire cockpit.

Soooooo...if it had an Erla Haube...it was not pressurized.

The only way it could have been pressurized, is if it had the 3-piece G3/G5 Canopy.

Please read my earlier post on the topic. A pressurized Erla Haube was designed and prototyped. There are two photographs of it in Schmoll (2017, p. 173). As I noted, this pressurized Erla Haube was significantly different in construction from a regular Erla Haube. The framing was reinforced, double walled transparencies with silica gel pellets were installed, there was a pressure seal around the entire circumference, and a pressure bulkhead at the back of the Haube, in front of the luggage compartment. The windscreen was also redesigned and incorporated heating. In many respects, it was an entirely new canopy from a technical point of view - but it retained the overall lay-out of a regular Erla Haube.

Reference:

Schmoll, P. 2017. Me 109. Produktion und Einsatz. MZ-Buchverlag, Regenstauf, Germany. 312 pp.

[pvanroy]

On a related note, I remember that over a decade ago, David Wadman announced that he had discovered two photographs of the 109 H operated by 5.(F)/123 in a German private collection, and had obtained rights to publish one of those images in an upcoming book of his (while negotiating the release of the second image). Nothing seems to have ever come of this. Does anyone here know more about this? It would be amazing to finally have some photographic evidence of this aircraft!