Junkers EFo designations

[Jemiba]

As proposed by Artie , I'll start to list the "EFo" designations, found in Wolfgang Wagners book "Hugo Junkers. Pionier der Luftfahrt - seine Flugzeuge". They all are belonging to models for the windtunnel, or for towed tests and as said before,
cannot always be regarded as "projects". All pictures (in low res only) are from the mentioned book.

EFo-08 high-altitude bomber, 2 jet engines
EFo-09 single-seat fighter, 10 jet engines, prone pilot
EFo-11 single-seat fighter, 2 jet engines
EFo-12 bomber, 4 jet engines

 

[Jemiba]

EFo-15 improved EFo 012
EFo-17 single-seat fighter, 2 jet engines, similar to Me 262
EFo-18 single-seat short range fighter, 4 jet engines
EFo-19 single-seat fighter, 2 jet engines

 

[Jemiba]

EFo-21-3 six-engined trans-atlantic passenger aircraft (coupled engines)
EFo-22 record aircraft, 2 jet engines
EFo-43 towed model. probably for a guided glidebomb

 

[blackkite]

Wow! Super. You made my day.

 

[richard]

The EFo 22 is sometimes refered as EFo 10 ...



Heinkel He343 (reply #31 )

 

[theponja]

Fantastic Work Jemiba. Thanks a lot!!!

I wonder which was the idea behind the efo-11. Why the engines in that position?

 

[Stargazer]

Great topic. Thanks for sharing!

 

[Jemiba]

I wonder which was the idea behind the efo-11. Why the engines in that position?

Judging the quite similar profiles of the fuselages of those twin-engined fighter designs, I think,
it was just to test the pros and cons of different engine installations. There still were very few
real experiences with jet aircraft, so it was a phase of trial-and-error.
Reasons that made this layout interesting could have been the unobstructed wing and fuselage,
that allowed for a quite small aircraft.

 

[toura]

Hi Jens
Thanks for the job ! Beautiful !
but
I've read that the EFo 22 come from the EFo18
and this EFo 22 is like the EFo 10 ?
(See my drawing)

And more, could you tell us what is the signification
of "EFo" and "EF"

 

[toura]

I've found :
" Entwicklungs--flugzeug"
in French : avion en cours de developpement
in English ( perhaps) development aircraft

 

[Jemiba]

I've found :
" Entwicklungs--flugzeug"
in French : avion en cours de developpement
in English ( perhaps) development aircraft

Yes, that's what I've found, too ! But honestly, I don't believe it, apart from the fact,that it wouldn't
fit for the "EFo" designations. But still yet, I've found no better explanation, but asked in the German
Flugzeugforum. Let's wait, perhaps we'll get a plausible answer.
BTW: I've found a list, which might be helpful, too:
http://www.lwag.org/forums/archive/index.php/t-2329.html

 

[Jemiba]

Got an answer from Peter Achs, aka "Junkers-Peter" in the Flugzeugforum, a specialist for Junkers
aircraft. Paul, you're right, "EF" stould for "Entwicklungsflugzeug" (aircraft design). In the abbreviation
"EFo", "E" stands for "Entwicklung", too, and "Fo" for "Forschungsvorhaben" (researchproject).
That means, that at least the EFo-numbers weren't all assigned to aircraft designs, but to engines, or
general aerodynamic researches. So, we should be aware, that not every number can be supplemented
with a 3-view. And, btw, Peter quoted from a letter to the editor he sent to the Jet & Prop magazine
in March 2004 just about this theme, were he warned about putting too much faith in Wolfgang Wagners
statements about the EFo/EF designations, although he mainly meant the general history and not explicitly
the list.
Seems, there's still a lot of work left for us !

 

[Stargazer]

Got an answer from Peter Achs, aka "Junkers-Peter" in the Flugzeugforum, a specialist for Junkers
aircraft. Paul, you're right, "EF" stould for "Entwicklungsflugzeug" (aircraft design). In the abbreviation
"EFo", "E" stands for "Entwicklung", too, and "Fo" for "Forschungsvorhaben" (researchproject).

What is still unclear to me is whether the EF and EFo lists are one and the same or if they were separate...

 

[Jemiba]

They were two separate lists. The EF designations were used by the "Konstruktionsbüro - KoBü",
probably best translated as "design office". Those numbers actually should have been used for
aircraft designs, whereas the EFo designations came from the "Forschungsabteilung" (Research
department) and were used for all objects of research, Peter Achs brought as an example a report
about a "Luftschraube mit veränderlichem Durchmesser" (propeller with variable diameter), which had
an EFo-designation, too. And he added, that numbering of projects of the research departments
was completely independent from that of the design offices.
Just my thought, but here we could have a reason for those strange duplicates, when over the years
EFo- and EF-designations were mixed up.

 

[Michel Van]

and to make things even more complicated


according the Book "Hugo Junkers Pionier Der Luftfahrt - seine Flugzeuge" by Wolfgang Wagner
once a EFo project got a windcannel model, the designation change to EF !


The List are not great help because the project explanation are in Telegram style


sorry, but we german have this pesky habit to abbr. and "to be brief" in documents :-[

 

[Jemiba]

Got another clue from Peter Achs. EFo-designations without another letter (e.g. EFo T.702)
generally were aircraft designs ! The "Forschungsabteilung" (research department) was dissolved
in 1942 and the remaining engineers and technicians integrated into the design teams. That probably
would explain, that the use of EFo-designations stopped.
If the designations for both departments (EF and EFo) formed a chronologically complete list, I don't
know.
Michel, you're right, the telegram style descritions aren't very helpful, but photos of the models are,
I thin. We just have to be aware, that for the assigned designations in Wagners book, we actually
have no proof. Maybe he had the original photos, stamped and with notes on the backside, but maybe
the numbers were, at least sometimes, only deduced.

BTW, Michel, do you read the Flugzeugforum ?

 

[Michel Van]

Got another clue from Peter Achs. EFo-designations without another letter (e.g. EFo T.702)
generally were aircraft designs ! The "Forschungsabteilung" (research department) was dissolved
in 1942 and the remaining engineers and technicians integrated into the design teams. That probably
would explain, that the use of EFo-designations stopped.
If the designations for both departments (EF and EFo) formed a chronologically complete list, I don't
know.

It cloud be a explanation why some junkers "project" have no proper EF or EFo designation
because they were "lost" during the transfer of the Foschungsabteilung into Konstruktionsbüro

my hope is that happened to this project: Junkers "Unnamed" ground attack aircraft
http://www.secretprojects.co.uk/forum/index.php/topic,14244.0.html

BTW, Michel, do you read the Flugzeugforum ?

Nope i'm not :-[

 

[theponja]

Is there any information about the dimensions of this projects, specially for the efo-11 ? Because I've seen some models for another efo projects , for example this one:

Unicraft 1/72 Junkers "Strahl Rekord Flugzeug"

www.unicraft.biz

but maybe they are just estimated ones, I understand Unicraft isn't very precise in some of their models.

BTW I'm continue wondering about the efo-11 project. The undercarriage is very "strange" seems to be just a central wheel with lateral skids.

 

[Jemiba]

Unicrafts model seems to be the EFo 22. About the landing gear of the EFo 11, you're right,
a central wheel and two outrigger skids. In Wolfgang Wagners book performance data are given
(max. speed 830 km/h, 790 km/h in 6000m, climb speed 40m/s, landing speed 130 km/h,endurance
15 minutes (!), take-off distance 200m), but no dimensions. That the pilot is shown in the drawing,
should make estimations possible and maybe the shown armament, which is said to be two MG 17.

 

[Jemiba]

And as in the EF thread, the list as a txt file:

 

[Stargazer]

I'm still not convinced that the EFo designators should get a separate treatment from the EF ones. Perhaps after all the two should be merged into a single one:

1°) All that I've seen so far seems to indicate that the EF numerals took over where the EFo ones stopped.
2°) Fo designations predated the EFo ones (Fo2 became EFo2, for instance). Junkers also used JM for Navy designs. A single topic on Junkers project designations could be enough.
3°) I haven't seen evidence of a duplicate between EF and EFo systems that would refer to two totally different projects.
4°) There is an obvious confusion between EF and EFo in many sources. EFo 12 can also be found as EF-012, EFo-12, EFo-012 and EF-12. Who can claim to have the right version?

I suggest these sites as pointers to help on these matters:
http://www.geocities.ws/hjunkers/ju_airc2.htm
http://hugojunkers.pytalhost.com/ju_airc2.htm (clone of the above)
http://www.flugzeugforum.de/forum/showthread.php?69482-Junkers-EFo-und-EF-Bezeichnungen

 

[newsdeskdan]

It seems to me that the EF and EFo lists are probably one and the same. Here are some pages from a Junkers document, which show that the company's own staff didn't really have a clearly defined way of writing these design designations. In one it appears as EF011, in another EFo11, we also get E.Fo-12 and E Fo-12.

 

[hesham]

It seems to me that the EF and EFo lists are probably one and the same. Here are some pages from a Junkers document, which show that the company's own staff didn't really have a clearly defined way of writing these design designations. In one it appears as EF011, in another EFo11, we also get E.Fo-12 and E Fo-12.

My dear Dan,that was my thought from long time ago.