Bf 109 H WNr.110073

[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

[Charles Bavarois]

The fotos of the pressurized Erlahaube were attached to a letter from Phänomen-Werke to Forschungsanstalt Oberammergau dated 28. Nov. 1944. They were to back up a not included report on testing the cabin 009.128-Z003/123-Z001. It is quite clear that the cabin was prototype only. IMHO a pressurized Erlahaube was not available for WNr. 110073 anyway.
One of the fotos has a handwritten note: "Windschutzaufbau 8-109.128-Z003 K3 - Z003 druckfest".

[harrison987]

Originally Posted by Charles Bavarois

The fotos of the pressurized Erlahaube were attached to a letter from Phänomen-Werke to Forschungsanstalt Oberammergau dated 28. Nov. 1944. They were to back up a not included report on testing the cabin 009.128-Z003/123-Z001. It is quite clear that the cabin was prototype only. IMHO a pressurized Erlahaube was not available for WNr. 110073 anyway.
One of the fotos has a handwritten note: "Windschutzaufbau 8-109.128-Z003 K3 - Z003 druckfest".

Correct...

Even the Me109K never had it in 44/45. Impossible for the H model to have it in 1943 when it was not even available (and probably still on the drawing board).

[Graham Boak]

The Guyancourt operation wasn't 1943.

Unlike the K, however, the Hs was based on G-5 airframes, so were pressurised already. It seems to me that it wouldn't have been a great task for a prototype to block off the rear of the cockpit opening to seal it and permit the fitting of a standard Erla canopy. I don't recall mention of the G having anything other than a standard canopy, perhaps this is wrong. I don't say that this was done, just that it seems to be well within the capability of the prototype workshop shop. Something of a bodge rather than proper production standards.

[pvanroy]

Just a couple of points:

1. No-one in this thread ever claimed that 110073 was definitely equipped with a pressurized Erla Haube. Piero suggested that it had received an Erla Haube at some point, to which I replied that if this was the case, it would be quite interesting, as this would need to have been a pressurized Erla Haube - which is not entirely inconceivable considering a pressurized Erla Haube was prototyped. That's all.

2. Of course, if the construction of the pressurized Erla Haube post-dates the May-July 1944 time frame (NOT 1943 as misquoted by harrison987) of the use of 110073 by 5.(F)/123, that machine obviously cannot have been equipped with it.

3. Modifying a regular unpressurized Erla Haube for cabin pressurization, as Graham Boak suggests, would not really be possible. The construction and materials of the regular Erla Haube are simply too flimsy to withstand the pressure differential. It would also have been difficult to accommodate the double canopy glazing required by the cold wall-type pressure cabin used by the G-5. The pressurized Erla Haube really required an almost entirely new design from an engineering point of view.

4. The date of 28 November 1944 as cited by Charles Bavarois for the letter to which the photographs of the the pressurized Erla Haube was attached poses an interesting question: what purpose did this work serve at that point, as by that time both pressurized versions of the K series and the H series had been long abandoned? Also, if these photos were part of a test report, the pressurized Erla Haube clearly must have existed before that date.

5. Harrison987's argument that "Even the Me109K never had it in 44/45" is a non-sequitur: the only K version produced in series was the K-4; in addition, there may have been two K-2 airframes, and one K-6 converted from a K-4. All these machines lacked cabin pressurization, so why would they be equipped with a pressurized Erla Haube? The G-5 was the last pressurized 109 produced in series, with the final machines being delivered by Erla in June 1944. So, after that date, there was simply no longer any requirement to produce pressurized canopies of any type for the 109 - and obviously no need at all to equip unpressurized aircraft (i.e. all K machines constructed) with a canopy set up for pressurization.

6. Years ago, George Hopp posted on LEMB a document entitled "Me 109H/ DB 628 Höhenjäger Kurzbeschreibung", dated 27 May 1943. You can download it here:

https://disk.yandex.com/i/F_uGWbCHbTW9GQ

Interestingly, in the description of the fuselage, it states "Normaler Me 109 G 5 Rumpf mit Druckkabine ohne GM 1 Anlage, jedoch mit folgenden Änderungen: ... ohne Panzerscheibe, Kopfpanzer, Rückenpanzer, Leichtmetallrückenpanzer..." So, if I understand this correctly, this aircraft (likely referring to the V49, possibly V50) had a pressure cabin, but lacked the head armor. In the regular three-piece pressurized canopy, the head armor doubled as a pressure bulkhead, and was an integral part of the central hinged portion of the canopy. Hence, removal of the head armor in the standard three-piece pressurized canopy would have resulted in the loss of cabin pressurization. Yet, this aircraft is described as pressurized.

In summary, I am not at all arguing that 110073 definitely had a pressurized Erla Haube - in fact, as I've clearly indicated in my earlier posts in reply to piero, I think it is quite likely that the machine had a standard three-piece pressure canopy during its entire existence. However, I do feel, that, on balance, the possibility that this experimental aircraft at some point might have received a pressurized Erla Haube cannot be entirely discounted. Hopefully, the photos mentioned by David Wadman al those years ago will one day show up!

Many thanks to Nick Beale and Charles Bavarois for providing the transcripts, and for further information regarding the pressurized Erla Haube!

[pvanroy]

Originally Posted by piero

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

One more thing I thought about for your reconstruction: testing of the V54, and experience with the G-6/AS showed that the standard Fo 870 oil cooler provided insufficient cooling capacity. As a result, the V54 was to be refitted with the larger Fo 987 oil cooler, which was also introduced during G-14/AS production, and retrofitted to some G-6/AS. Therefore, 110073 possibly may have been equipped with the larger Fo 987 oil cooler. We really need to see the photographs that purportedly exist of that aircraft!

[ArtieBob]

I have not seen the photographs, but there is a 3-view drawing, which appears to be of Me origin on microfilm of the captured German documents at The US National Air and Space Museum. It is not a very good image, but it is pretty well dimensioned and shows some internal detail, i.e. location of the GM-1 tank, etc. Of course, the real aircraft may not appear exactly the same as the drawing, but the canopy on the drawing certainly does not appear to be the Erla type.
Best Regards,
ArtieBob