Bf 109 H WNr.110073

[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]

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.

As a follow up to my previous message, in case you - or anyone else - is interested to see what a pressurized Erla Haube looks like: I took a quick snap of the photos on p. 173 of Schmoll (2017), and they can be downloaded here:

https://disk.yandex.com/i/q0JjZkR1z22YoQ

Apologies for the poor quality.

[harrison987]

Thanks for the image...



Here is the problem though...

This was never implemented. Prototype only.

So, the H model would never have had this...

[Nick Beale]

Originally Posted by harrison987

Thanks for the image...



Here is the problem though...

This was never implemented. Prototype only.

So, the H model would never have had this...

But could you describe the Bf 109H that flew with 5.(F)/123 as anything more than a prototype or experimental model? It wasn’t in series production and it wasn’t a standard Umrüst Bausatz, was it?

[piero]

Given the content of post n. 1, I would be very interested.
Giampiero Piva