JU 252 352

[ralphwiggum]

Were either of these airplanes ever used in combat related roles or did they end up only for tests
I heard that that the JU 252 production had just gotten into swing when the worsening of the war cancelled it
I don't know anything about the JU 352 I just saw a few pics and thought it'd be a shame if it never got used

 

[Siegfried]

The Ju 252 had phenomenal performance as a transport. I believe they were used in small numbers to ferry fuel and supplies to Nth Africa and were capable of delivering 4 tons of fuel and return without refueling themselves.

Maximum speed was 272 mph (438 km/h) with a maximum cruising speed of 242 mph (390 km/h). The service ceiling was 20,670 ft (6300 m). Range of 2,473 miles (3980 km) with maximum payload. With only 4,410 lbs (2000 kg) of payload range increased to 4,100 miles (6600 km). Empty the aircraft weighed 28,880 lbs (13100 kg), with a normal loadout it weighed 49,560 lbs (22480 kg) and with maximum overload it weighed 52,910 lbs (24000 kg).

Aircraft of the Luftwaffe gives a maximum payload of 11000kg, I assume this is in the overload condition so 9.5 tons normal cargo may have been possible but I have the impression the payload was 5.5 tons with max fuel. (Possibly got that from Luftwaffe the allied intelligence files book) without using overload weights.

Either way some 5.5 tons of cargo flown 2400 miles means the Luftwaffe might have supplied around 5 tons of cargo to Stalingrad all the way directly from Berlin without refueling for the return flight. If you look at the performance of the Ju 52 you can see why they had so much trouble doing this.

 

[davebender]

I agree.

I've never understood why the Luftwaffe refused Jumo211 engines for the Ju-252 aircraft program. By 1942 Junkers was producing Jumo211 engines like hot rolls. In fact Jumo211 engine production declined after 1942 due to a lack of demand by aircraft manufacturers.

Forcing a switch to Bramo 323 engines (i.e. Ju-352) crippled performance. There was little point to replacing the dirt cheap Ju-52 with the Ju-352. So the program died.

 

[Gixxerman]

I must admit I don't know a lot about these planes but I had thought the Ju352 was really all about saving on strategic materials and that because of the lack of these materials the Ju252 simply couldn't be afforded.
My own reading of the situation was that by the time the Ju352 was ready the walls had closed in so much (not to mention the schools transport units having been decimated by Stalingrad and later the allies fighters roaming almost everywhere) that proceeding was pointless utterly futile and so all resources went to fighters to try to stave off the inevitable.

 

[pbfoot]

Either way some 5.5 tons of cargo flown 2400 miles means the Luftwaffe might have supplied around 5 tons of cargo to Stalingrad all the way directly from Berlin without refueling for the return flight. If you look at the performance of the Ju 52 you can see why they had so much trouble doing this.

Better than the LW Bombers

 

[davebender]

The Ju-52 had its good points. In addition to being reliable and dirt cheap it could operate from improvised airfields.

The Ju-252 had a far superior range / payload but I suspect it required a proper runway. Rather like the modern day C-5 vs a C-130.

 

[Siegfried]

I must admit I don't know a lot about these planes but I had thought the Ju352 was really all about saving on strategic materials and that because of the lack of these materials the Ju252 simply couldn't be afforded.

My own reading of the situation was that by the time the Ju352 was ready the walls had closed in so much (not to mention the schools transport units having been decimated by Stalingrad and later the allies fighters roaming almost everywhere) that proceeding was pointless utterly futile and so all resources went to fighters to try to stave off the inevitable.

Nothing became of the Ju 352 either as it took so long develop so this was a poor decision; admitedly advanced versions of the Ju 352 with more advanced engines started to approach Ju 252 performance once again.

The Ju 252 flew in October 41 over one year before a decline in German fortunes. It could have been much earlier bar 1/ A period of suspension of work to focus the immediate war effort around 1940 and 2/ an elaborate but probably unnecesary redesign for luftwaffe needs.

I suspect replacing individual components with non stratefic ones is a much better approach: door covers, access hatches, propellers, flaps, ailerons, rudders, elevators, floors can all be replaced. They may have been better of with a few hundred Ju 252 than no Ju 352

Like most aircraft of the 1930s and 1940s the Ju 252 was built to opperate of grass fields, however its wing loading was higher about 180kg/sqm vs 100kg/sqm for the Ju 52 but this is not so much for its day and in most cases not critical. If short airfield is required a Ju 52 could still be used or better still an Ar 232, an aircraft with an extraordinary short field performance or the Ju 252 simply opperated with a light load of fuel and or cargo. Landing at a rough field destination would occur only after the fuel had been burned of while the takeoff would be generally devoid of heavy cargo and with less than half a load of fuel.

 

[davebender]

I agree. If the Ju-52 were to be replaced the Ar-232 was the proper replacement.

The Ju-252 would be a larger and heavier supplement. Ideal for missions where large payload really matters such as flying supplies between Sicily and Tunisia.

 

[davebender]

Payload = max aircraft weight minus aircraft empty weight.

4,480kg. Ju-52/3m
7,100kg. Ju-352.
7,269kg. C-47.
8,370kg. Ar-232.
10,923kg. Ju-252.
17,495kg. Ju-290.

That puts things in perspective. By powering the Ju-252 with Bramo 323 engines (i.e. Ju-352) the aircraft has 3,823kg less payload.

The Ar-232B has Bramo 323 engines also but it has four to compensate for the relatively low power output. Consequently the Ar-232B has a greater payload then the Ju-352 plus superior rough airfield capability and it is easier to load / unload. Replace the Bramo engines with four 1,350hp Jumo211 engines and I suspect the Ar-232 would be a military transport superstar (for the WWII era).

 

[pbfoot]

Lets use the proper numbers in useful payload , at least proper as far as internet searching maybe someone can come up with the 252 numbers
JU 52 1845kg
C47 3000kg
C46 6800kg
c54 9000kg

 

[tyrodtom]

Payload isn't the difference between empty weight and max loaded weight. It's empty weight plus crew and fuel, and whatever else the aircraft has to carry for flight, payload is whatever weight the aircraft can take off with after that. So payload can vary with how much fuel is carried.

 

[davebender]

Payload isn't the difference between empty weight and max loaded weight. It's empty weight plus crew and fuel

All aircraft require crew and fuel. So I think max weight minus empty weight works ok for comparing aircraft payload. People just need to understand that cargo load or bomb load is going to be considerably less then total aircraft payload. How much less depends on distance to be flown and (especially for U.S. bombers) the number of defensive weapons and gunners.

 

[pbfoot]

All aircraft require crew and fuel. So I think max weight minus empty weight works ok for comparing aircraft payload. People just need to understand that cargo load or bomb load is going to be considerably less then total aircraft payload. How much less depends on distance to be flown and (especially for U.S. bombers) the number of defensive weapons and gunners.

Disagree its a huge difference , start throwing in oil and other stuff

 

[Siegfried]

Lets use the proper numbers in useful payload , at least proper as far as internet searching maybe someone can come up with the 252 numbers
JU 52 1845kg
C47 3000kg
C46 6800kg
c54 9000kg

It's very difficult to know what these numbers mean, too many books have been written by non pilots and non engineers in which the 'range' of an aircraft is not specified with the standard opperating conditions such as payload being carried and the cruise speed used and the reserves allowed for.

Nor do they note special conditions such as paved runway (which can allow an overload if there are no objects close to the end of the runway)

Using Dave's figures one can say that a Ju 252 can be loaded with 10,932Kg of cargo (non overload) and would then be at its MTOW (Max Take Off Weight) and of course unable to takeoff because it could not carry any fuel. If we remove 932kg of cargo and replace it with fuel we have about 2100lbs of fuel. The Jumo 211 was one of the more efficient piston engines and consumed fuel at about 0.48lbs/hp/hr (less in cases). So the aircrafts total 3 engines of total 4050hp could have been run at full power for over an hour: enough for takeoff and a 220-240mph cruise for about one hour at about 66% power. IE a range of about 200-250 miles. At the other extreme we can immagine the aircraft taking of with say 7 tons of fuel and cruising at 50% power with 2 tons of cargo.

The same applies to the DC-3/C-47

This kind of short range delivery was occaisionally performed.

A particular strength of the Ju 252 seems to have been very good cruise efficiency combined with large fuel capacity.

I did a spreadsheet calculation once of how much fuel, in tons, that it would take to deliver 1 ton of cargo 1000km.

The DC-3 was particularly efficient however the Ju 252 outshone it (bigger airraft better engines). The Ju 52 was not very good though its latter versions were improved. I am working internationally now so can't retrieve my data.

When delivering cargo short distances this fuel efficincy doesn't count too much (say under 300 miles) nor is it critical if a light cargo (passengers with luggage) is taken medium distances to say regional airports with short grass strips. However as distance is increased the fuel demands are a great burden. It may take a ju 252 3.5 tons of fuel to deliver 1 ton of cargo 4000 miles but it would take a Ju 52 about 5 tons, however the Ju 52 would need to do this in 6 hops instead of one and if the Ju 252 was also allowed to split its joourney its efficiency great increases for instance if the Ju 252 does the the journey in two 2000 miles hops the efficiency seems to allow 4 tons of fuel to be used to deliver 5.5 tons of cargo.
this works out at about 1.2 tons of fuel to deliver 1 ton of cargo 4000 miles split into 2.

As I recall I used data from a book called Luftwaffe the allied intelligence files which put standard Ju 252 fuel capacity at 4096kg.

In other works the Ju 252 was 4 times more efficient at delivering a cargo than the Ju 52.

The DC-3 comes across as a good compromise.

 

[Siegfried]

I agree. If the Ju-52 were to be replaced the Ar-232 was the proper replacement.

The Ju-252 would be a larger and heavier supplement. Ideal for missions where large payload really matters such as flying supplies between Sicily and Tunisia.

It'a also possible to immagine other scenarios: for instance if the Luftwaffe gets a 4 engined bomber in service in early 1941 (when the Halifax Lancaster performed their first missions) or even early 1942 then FW 200 production can be reallocated from maritime patrol to transport. The Ju 52 then only has to perform deliveries to smaller rougher fields and would then best be replaced with the Ar 232 which does this role much better. The Ju 252 was however faster than the FW 200 and therefore harder to intercept and would have had an big efficiency advantage due to short turnaround times from the trappoklappe.

 

[pbfoot]

So does paint count on empty or all up weight . Now comparing the 47 to the 252 is akin to comparing a DHC Beaver to an Dhc Otter . Compare the c46 to the 252 also if you want toss in the FW 200 a good comparison is the C54

 

[Shortround6]

So does paint count on empty or all up weight .

It kind of depends

do you want the plane painted or not?

Bright aluminium finish might be OK for a rear area transport, California to Hawaii or even East Coast to England. Might not be so good for Warsaw to Stalingrad or flying the Hump into China. All that shiny aluminium is going to draw somebodies attention.

Weight of paint on a Martin Mars was about 550lbs. smaller planes are going to have a lot less paint.

Sometimes useful load and payload were interchangeable terms. Sometimes payload did refer to the weight available after crew, oil (normal), and fuel (standard tanks) and "normal" equipment ( radios and such) were added to the empty weight. Optional fuel tanks and fuel ( and extra oil) would have to be subtracted from the "payload".

The only practical way to compare cargo aircraft is if you can find a specification that gives a range with weight of cargo and includes the amount of fuel used and speed. Cruise speeds were all over the place, many planes had a variety of fuel tanks ( and tanks that used cargo spaces can really screw up a comparison) Crews varied from 2 to 5. field length also varied with weight (and climate conditions).

 

[pbfoot]

and on a 747 its over a 1000kgs IIRC Useful payload is a fully fuelled and oiled aircraft including paint and all , whatever is left over is useful load. and remember all that accumulated dirt and grime in the aircraft adds up as well .

 

[Shortround6]

On a lot of passenger/cargo planes the useful payload is NOT for a "fully' fueled and oiled aircraft. depending on the stage length ( particular route flown) a plane could be filled with less than full tanks and allowed more passengers or cargo, exact same plane could then fly the next stage of the flight with a different fuel/cargo combination. Even DC-3s had what were referred to as auxiliary tanks. On modern jets the "useful" load can vary by tens of thousand's of pounds depending on fuel load.

 

[davebender]

I agree.

However I don't think cruise speed with payload is nearly as important for a transport as it is for a bomber. Cargo aircraft tend to fly in relatively safe airspace. They cruise at economical speed rather then the fastest speed in order to minimize the amount of payload which must be reserved for fuel.