Junkers G.38/JU-89/JU-90/JU-290

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T. A. Gardner
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Re: Junkers G.38/JU-89/JU-90/JU-290

#16

Post by T. A. Gardner » 18 Aug 2016, 22:52

The problem remains that the G.38 when redesigned might as well be a new plane.

Image

Without the thick wing you lose most of the cargo space. You can't have the fuel tanks in the original arrangement and are likely to lose a considerable volume of fuel along with putting the thin wing on. The original wing is nearly 2 meters thick at the root.

You'd also have to come up with a totally new low drag radiator and oil cooler design as the G.38 has these slung below the wing. The plane cruised at about 100 mph at most. You'd need a 50 to 100% increase in that to make it competitive with 1940's designs.

It simply is obsolete technology all the way around by the mid 30's

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Re: Junkers G.38/JU-89/JU-90/JU-290

#17

Post by thaddeus_c » 19 Aug 2016, 04:13

T. A. Gardner wrote:Without the thick wing you lose most of the cargo space. You can't have the fuel tanks in the original arrangement and are likely to lose a considerable volume of fuel along with putting the thin wing on. The original wing is nearly 2 meters thick at the root.

You'd also have to come up with a totally new low drag radiator and oil cooler design as the G.38 has these slung below the wing. The plane cruised at about 100 mph at most. You'd need a 50 to 100% increase in that to make it competitive with 1940's designs.
never mentioned a thin wing? perhaps I was unclear? did voice eliminating the glass expanses on either side.

switch to radial engines would seem logical as they had plateau in development of diesel engines.

fixed landing gear similar to ME-323 is my own scenario but does not seem too far fetched if the aircraft is being used as transport primarily? and landing in places like Kabul where rough airfields to be expected.


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Re: Junkers G.38/JU-89/JU-90/JU-290

#18

Post by T. A. Gardner » 19 Aug 2016, 04:39

thaddeus_c wrote:
never mentioned a thin wing? perhaps I was unclear? did voice eliminating the glass expanses on either side.
Those make up part of the wing. The problem is that the wing is huge. It is 1.7 meters thick at the root (where the glass is). The glass was there as the front portion was used for passenger seating and viewing. Eliminating the glass does nothing to fix the problem at hand. The wing is too thick and has a very thick section and is extremely wide.
That's great for low speeds and more lift. Given the weak engines that was a good design. Adding more power won't make the plane appreciably faster as the wing's drag will increase nearly exponentially as speed does. You need a much thinner wing with greatly decreased width. You also need to get rid of the corrugated wing covering to reduce drag at higher speeds.
switch to radial engines would seem logical as they had plateau in development of diesel engines.
Switching engines does nothing to fix the fundamental problem the design is one for low speed using 1920's technology that is obsolescent at best by 1935.
fixed landing gear similar to ME-323 is my own scenario but does not seem too far fetched if the aircraft is being used as transport primarily? and landing in places like Kabul where rough airfields to be expected.
Again, it's a minor fix to an aircraft that was best replaced. Junkers did brush off that wing design for their Ju 322 Mammut glider. This flew at low speed nicely once in the air. Getting it there was the issue...

Image

I doubt sticking 6 to 8 engines on it would have fixed it's problems...

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Re: Junkers G.38/JU-89/JU-90/JU-290

#19

Post by thaddeus_c » 19 Aug 2016, 14:00

T. A. Gardner wrote:
thaddeus_c wrote:
never mentioned a thin wing? perhaps I was unclear? did voice eliminating the glass expanses on either side.
Those make up part of the wing. The problem is that the wing is huge. It is 1.7 meters thick at the root (where the glass is). The glass was there as the front portion was used for passenger seating and viewing. Eliminating the glass does nothing to fix the problem at hand. The wing is too thick and has a very thick section and is extremely wide.
That's great for low speeds and more lift. Given the weak engines that was a good design. Adding more power won't make the plane appreciably faster as the wing's drag will increase nearly exponentially as speed does. You need a much thinner wing with greatly decreased width. You also need to get rid of the corrugated wing covering to reduce drag at higher speeds.
yes, I believe I understand it was part of the wing structure. was suggesting glass expanse as well as other passenger features eliminated in conversion to transport. hopefully aid in aerodynamics over the wing and weight.

radial engines, landing gear, and tail assembly would aid in drag also cribbed from contemporary designs.

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Re: Junkers G.38/JU-89/JU-90/JU-290

#20

Post by Simon Gunson » 04 Dec 2016, 03:35

thaddeus_c wrote:what if Junkers had been able to develop the G.38 into transport and bomber instead of the JU-89/JU-90/JU-290?
In fact the Japanese did. They purchased six G-38 as airliners, then converted them to bombers.

http://blog.goo.ne.jp/a_tranquil_smoker ... ef99367e7d

The Type 92 was an earlier G-38 airliner from Junkers of Germany remodeled by engineer Nobuyoshi Nakada as Japan's K51 bomber for Mitsubishi Aircraft Co., Ltd. Although six of these bombers were built under license from Junkers the K-51 project stalled due to logistic issues at Mitsubishi 's Oei Factory. This forced the IJA to consider purchasing the Ju90 via a secret deal with Manshukuo National Airways & then convert aircraft into bombers [1][2]

Specifically the deal involved a proposal for Manshukoku National Airways to acquire ten Ju90 aircraft powered by the DB 600C & operate the Ju90 on a non-stop route over Russian airspace between Harbin and Berlin. The deal would be paid for by the export of Soy Beans from Manchukuo. For the Ju90's redesign, 30 technicians from the Imperial Japanese Army and 20 from Mitsubishi were to be selected and dispatched.

The Ju90 was redeveloped as an airliner from the Ju89 specifically to beat sanctions designed to prevent export of warplanes to Japan. On 27 May 1938 the vessel Yasukuni Maru departed from Kobe with the head office's business section chief, Takeda Jiro and five engineers including Akimoto Minoru to begin advance preparations for the project. The team toured Junkers' Dessau plant on 25 July 1938.[3]

The deal collapsed for a number of reasons including the unavailability of DB600C engines for the project, but most importantly because Hitler changed his position during the 2nd Sino-Japanese war and declared German support for Japan. This prompted conflict with Russia and blocked any option of a Ju90 air-bridge to Harbin.

[1] Japanese-German Business Relations: Co-operation and Rivalry in the Interwar by Akira Kudo
[2] Tsurezure tobacco: Japanese blogsite Re Dainippon Paintings; Supplementary Revised Edition (1997/07)
Language: Japanese ISBN-10: 4499226775
[3] Mitsubishi Ki-20: Mikesh, Robert C.; Shorzoe Abe (1990). Japanese Aircraft, 1910-1941. London: Putnam Aeronautical
Books. ISBN 0-85177-840-2

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Re: Junkers G.38/JU-89/JU-90/JU-290

#21

Post by thaddeus_c » 05 Dec 2016, 01:53

Simon Gunson wrote:
thaddeus_c wrote:what if Junkers had been able to develop the G.38 into transport and bomber instead of the JU-89/JU-90/JU-290?
In fact the Japanese did. They purchased six G-38 as airliners, then converted them to bombers.

The Type 92 was an earlier G-38 airliner from Junkers of Germany remodeled by engineer Nobuyoshi Nakada as Japan's K51 bomber for Mitsubishi Aircraft Co., Ltd. ... This forced the IJA to consider purchasing the Ju90 via a secret deal with Manshukuo National Airways & then convert aircraft into bombers [1][2]

Specifically the deal involved a proposal for Manshukoku National Airways to acquire ten Ju90 aircraft powered by the DB 600C & operate the Ju90 on a non-stop route over Russian airspace between Harbin and Berlin.

The Ju90 was redeveloped as an airliner from the Ju89 specifically to beat sanctions designed to prevent export of warplanes to Japan.

The deal collapsed for a number of reasons including the unavailability of DB600C engines for the project, but most importantly because Hitler changed his position during the 2nd Sino-Japanese war and declared German support for Japan. This prompted conflict with Russia and blocked any option of a Ju90 air-bridge to Harbin.
thanks for all the information!

guess it inevitable Junkers evolved away from G.38 design? although the JU-290/390 had its own problems.

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Re: Junkers G.38/JU-89/JU-90/JU-290

#22

Post by Cantankerous » 15 Jan 2024, 02:58

thaddeus_c wrote:
05 Dec 2016, 01:53
Simon Gunson wrote:
thaddeus_c wrote:what if Junkers had been able to develop the G.38 into transport and bomber instead of the JU-89/JU-90/JU-290?
In fact the Japanese did. They purchased six G-38 as airliners, then converted them to bombers.

The Type 92 was an earlier G-38 airliner from Junkers of Germany remodeled by engineer Nobuyoshi Nakada as Japan's K51 bomber for Mitsubishi Aircraft Co., Ltd. ... This forced the IJA to consider purchasing the Ju90 via a secret deal with Manshukuo National Airways & then convert aircraft into bombers [1][2]

Specifically the deal involved a proposal for Manshukoku National Airways to acquire ten Ju90 aircraft powered by the DB 600C & operate the Ju90 on a non-stop route over Russian airspace between Harbin and Berlin.

The Ju90 was redeveloped as an airliner from the Ju89 specifically to beat sanctions designed to prevent export of warplanes to Japan.

The deal collapsed for a number of reasons including the unavailability of DB600C engines for the project, but most importantly because Hitler changed his position during the 2nd Sino-Japanese war and declared German support for Japan. This prompted conflict with Russia and blocked any option of a Ju90 air-bridge to Harbin.
thanks for all the information!

guess it inevitable Junkers evolved away from G.38 design? although the JU-290/390 had its own problems.
The last lifting body aircraft designed by Junkers was the Ju 322 Mammut transport glider. After the Ju 322 made two flights impaired by longitudinal instability, the RLM had the production contract for the Ju 322 canceled.

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Re: Junkers G.38/JU-89/JU-90/JU-290

#23

Post by Peter89 » 15 Jan 2024, 09:18

Ju G.38 was a woefully obsolete plane by the outbreak of WW2. The Ju 90, on the other hand, was one of the most promising design for heavy transport and remained competitive during the whole war.
"Everything remained theory and hypothesis. On paper, in his plans, in his head, he juggled with Geschwaders and Divisions, while in reality there were really only makeshift squadrons at his disposal."

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