improved Ju 52

[thaddeus_c]

Germany never produced more modern transport in any numbers. read a suggestion for streamlined Ju 52 keeping the corrugated skin but with what was described as "Second skin" for aerodynamics, speculating on an increase in top speed and range.

would this be feasible to retrofit existing aircraft? could this be done with fabric? ( a portion of Me 323 was canvas IIRC)

(am not proposing to change fixed landing gear or radial engines)

[Sheldrake]

Rather than fiddle with an 1930 design based on leading edge WW1 methods the Germans took the same concept built it with logical step is to build an aircraft using more up to date technology

Hence the https://en.wikipedia.org/wiki/Junkers_Ju_252
and - using non strategic materials: The Ju 352,
https://en.wikipedia.org/wiki/Junkers_Ju_352
These would have comparable performance to the C47.
https://en.wikipedia.org/wiki/Douglas_DC-3

[T. A. Gardner]

Germany should have done what Japan and Russia did... Just get a license to produce Douglas DC 3's.

[thaddeus_c]

without doubt a replacement for Ju 52 the best plan. however there were huge inventories of existing aircraft and surplus of engines, assuming the Ju 52 carries on per historical timeline, what could be done to streamline fuselage, wings to gain better performance?

[T. A. Gardner]

without doubt a replacement for Ju 52 the best plan. however there were huge inventories of existing aircraft and surplus of engines, assuming the Ju 52 carries on per historical timeline, what could be done to streamline fuselage, wings to gain better performance?

Fine.

The best "fix" I can come up with is to redesign the aircraft to take two Wright Cyclone R-1820-60+ series engines with three blade variable pitch propellers in place of the three BMW 132's used. This eliminates the nose engine entirely.
The Wright motor (or equivalent) is almost exactly the same diameter, length, and weight as the BMW but puts out 1200 + HP instead of 725. That leaves the overall power the same. But, by eliminating about 1200 lbs of engine (the nose engine), and streamlining the nose you gain speed, range (you can carry fuel in lieu of the removed engine's weight), and simplify maintenance.

[thaddeus_c]

from AH

"Ju 52 was reliable and in production during 1939. Even if Ju 52 was not the most productive transport it was still good for short-range deliveries. By late war, they learned that jumping farther than your artillery could support was suicidal!
A fictional Ju 152 would be similar in size to Ju 52, with the same engines, but fly farther and faster because of smooth external lines. Our fictional Ju 152 would still have corrugated skins, they would just be the second smooth layer brushing the wind aside (aka. Shorts Skyvan). Control surfaces would remain corrugated to ease production (aka. modern Cessna and Piper light singles). Wing flaps and ailerons would need to move up into the trailing edge to reduce drag and icing.
Ju 152 undercarriage would still be fixed, but good streamlining would help improve cruise speed towards the 200 knot range.
Fixed undercarriage only becomes a disadvantage faster than 200 knots or if icing is encountered. More recently, Cessna Caravan lost its flight into known icing conditions certification in Canada because all those struts ice up too easily."

so a JU-152

[T. A. Gardner]

Actually, the corrugation doesn't add much drag at the low speeds the Ju 52 flies. The fixed undercarriage could have wheel pants but these add little to reducing drag. The two big drag reductions you could make are:

Switching to a twin engine layout that has the same power with three bladed fully adjustable props to make better use of the engine power. You need an engine of about 1100 + HP to do this, hence the Wright Cyclone R-1820-60 series.

and

Adding new NACA cowling designs to reduce drag on the two remaining engines.

Skinning over the corrugation would only add weight for little reduction in drag.

You could redesign the wings to eliminate the Fowler flap design of the control surfaces, but that'd be a lot more work than simply switching to two engines and putting a clean aerodynamic nose on the plane.

The combination of low drag engine cowlings and a twin engine layout with more power per engine would raise speed some, maybe 175 to 180 knots, but it would far more importantly reduce the plane's dry weight by over half a ton. The two engines would use less fuel per hour than the triple layout, and the weight reduction means you can either carry more fuel or cargo.

[Helmut0815]

IMHO they should better have developed the Arado Ar 232, the first real modern transport aircraft, using non strategic materials. The trimotor planes had a really outdated design.

best regards


Helmut

[T. A. Gardner]

While the Ar 232 would have been better, the problem is where do you get the engines?

The prototype used BMW 801's, but there weren't enough in production to allow its use on this plane. So, a four engine variant was developed using BMW 232 or Gnome Rhone engines instead. The Gnome Rhone's were unreliable, particularly in dusty or harsh conditions. And, having 4 engines in use complicates things considerably.

The other problem is the Ar 232 wouldn't have been available before mid 1942 at the earliest, and probably more like late 1942.

On the other hand, the proposed Ju 52 with two engine configuration would be possible much earlier. The Wright Cyclone engine was producing 1,000+ hp in 1939 and was widely available. Germany could have easily imported some prior to the war beginning for use, the only thing really stopping them is Nazi / German hubris at using a foreign aircraft engine.
The Germans could have sought a license to make these, or once the war starts just ignore the niceties of that and make them anyway. After France fell they could have pushed out tooling to Gnome Rhone and told the French to make the engine. Its way better than the French engine Gnome Rhone was producing.

[thaddeus_c]

You could redesign the wings to eliminate the Fowler flap design of the control surfaces, but that'd be a lot more work than simply switching to two engines and putting a clean aerodynamic nose on the plane.

The combination of low drag engine cowlings and a twin engine layout with more power per engine would raise speed some, maybe 175 to 180 knots, but it would far more importantly reduce the plane's dry weight by over half a ton. The two engines would use less fuel per hour than the triple layout, and the weight reduction means you can either carry more fuel or cargo.

the JU-352 used wooden wings as part of effort to conserve materials, as well as Bramo 323 radials which reached 1,200 hp in some variants.

[T. A. Gardner]

The Bramo 323 (a license derivative of the Bristol Jupiter) and the original BMW 132 (license copy of the P&W Hornet) show that the Germans could have gotten the Wright Cyclone in pre-war production. Simply swapping out the existing three engines for two Bramo 323's or two Cyclone copies would have fixed most of the issues with the Ju 52 until something better could be put into production. A aerodynamically cleaned up version could have eventually replaced the Ju 52... Say one with retracting landing gear, lowered drag, and better weight to power ratios.

[thaddeus_c]

The Bramo 323 (a license derivative of the Bristol Jupiter) and the original BMW 132 (license copy of the P&W Hornet) show that the Germans could have gotten the Wright Cyclone in pre-war production. Simply swapping out the existing three engines for two Bramo 323's or two Cyclone copies would have fixed most of the issues with the Ju 52 until something better could be put into production. A aerodynamically cleaned up version could have eventually replaced the Ju 52... Say one with retracting landing gear, lowered drag, and better weight to power ratios.

noticed the Dornier DO-24 flying boat used the Wright R engine in Dutch production but under German direction they began using the Bramo 323 https://en.wikipedia.org/wiki/Dornier_Do_24 (might give some indication of performance a similarly equipped JU-52 could achieve)