WWII MISTERIES: What happened with the JU390?

[comiso90]

interesting....

1946:

I can imagine a squadron of those being intercepted over the Atlantic by F8F Bearcats and Tiger cats...

A beautiful site...

.

 

[Njaco]

Was there any connection between the Ju 390 and the Bloch 161? They look awful similar.

 

[DerAdlerIstGelandet]

Was there any connection between the Ju 390 and the Bloch 161? They look awful similar.

How do they look similiar?

They dont look anything alike!

Here is a Ju 390:

 

[Njaco]

Yeah, you're right. I was looking at the nose and tail and totally forgot about how many engines.

 

[Soren]

Awesome a/c the Ju-390 was, absolutely awesome.

 

[drgondog]

Ummm, there are a few problems with this story . . .

.

The BMW 801 engine, at cruise, as I understand it, burned about 570 liters (150 gallons) of fuel per hour, or for
the 6 engine Ju 390, about 3,420 liters (900 gallons) an hour. For Green's declared 32 hours of flight, not counting
climb out consumption, headwinds, and other such inconvenient vagaries, that's a requirement for some 109,440
liters of fuel. And of course, 109,440 liters of fuel is in the neighborhood of 28,795 gallons (US), which would
weigh about 215,000 pounds.

But wait ... empty weight of the Ju 390 was 36,900 kilograms (81,350 pounds) and the fully loaded weight was
75,500 kilograms (166,448 pounds); and I presume that includes POL, crew and ancillary equipment.

So, figure: 166,448 pounds rated max weight versus 215,000 pounds in fuel, equals: 48,552 pounds over weight.
How do you suppose they got all that off the ground? Was there really a crew with enough gonads to attempt to
takeoff at almost 30% over rated weight limits? All in fuel? With the only one of the aircraft type in
existence? For some sort of navigational stunt?

And to pull off their stunt they're going to fly into a hostile coastal area that had near it some of the enemy's
more important aircraft production facilities, Grumman comes to mind, that had radar coverage and they're not
going to be detected? Maybe, but only if they run the last hundred miles or so, in and out, at about 150 feet (that
would do wonders for their fuel consumption, wouldn't it). And if you strip out defensive armament, cut crew size,
remove any armor, and self-sealing tanks, all in the name of weight savings (not that such could come close
to accounting for all the 48,552 over weight pounds), what happens when you just happen to run into a patrolling
PB4Y loaded for bear? PB4Ys knocked down about 343 Japanese planes, included 95 twin and multi engine types,
and five German planes (a Do 217, an He 177, and three Ju 88's). One PB4Y would be perfectly capable of chasing
down and ruining a stripped down Ju 390's day. Are you willing to take that chance for what is essentially a one
time stunt?

Then there's the small matter of geography. Look at a map. The New York coastline runs roughly from ENE to
WSW. "North" of New York, city or state, is over land. Jeez, you think if they managed to get some 510 nmi (half
the distance in the above maximum range variance) beyond their rated roundtrip range and ended up somewhere
west of Long Island Sound it would make a much better story. If they took pictures of the coast, they would have
had to turn around to do so.

And what about Reichs Marshall Fatty or Herr Goebbels? Don't you think they would trumpet such a feat to the
all the world? Yet, there is no record of such a propaganda coup.

Also, remember, there were only two of these airplanes, V1 and V2. According to "Die großen Dessauer.
Junkers Ju 89, 90, 290, 390. Die Geschichte einer Flugzeugfamilie" ("The Big Ones from Dessau. ... History
of an aircraft family") by Karl Kössler and Günter Ott, during the time period of this feat was supposedly
accomplished, the lone Ju 390 V1 was in Prague, arriving there on November 26th 1943. While at Prague,
V1 was involved with a series of flight tests, flying on Nov. 30th, and Dec. 2nd and 3rd. The flight on the 3rd was
to Merseburg. V1 returned to Prague on Dec. 10th. More flights were made: on 17th, and again on 30th and
31st of December. Still more flights in January 1944, on the 3rd, 5th, 7th, and 8th. From January 17th to the 23rd,
in-flight refueling tests were conducted with a Ju 290. More tests for aerial refueling took place in through
February and March in the Prague area. The preoccupation with flight tests in the December, January, February
and March time period would seem to knock single prototype Ju 390 V1 out of contention for four weeks duty
in FAGr 5 culminating in a side trip to New York..

And the Ju 390 V2? Well, there's some question as to whether or not that particular aircraft was ever actually
completed. If it was, as near as I can find, it would not have been completed before September 1944, s
ometime after the mission in question. Further, FAGr 5 evacuated from Monte de Marsan on August 20, 1944.
So, probably built too late and could not have possibly launched from Monte de Marsan.

With the wrong information even an otherwise reputable historian can make a mistake. Take a look at Eric
Hammel's Pacific Air War Chronology for the TF-38 strike casualties on 28 July 1945. Absolute hogwash. Similar
error appears in Clark Reynold's The Fast Carriers ... could they be feeding each other? Did someone mis-read
information published elsewhere? I have a TF-38 report for the period, it is way, way different than either Hammel's
or Reynolds' writing. Similarly, a recently published book by popular oral history genre writer, Gerald Astor, entitled
Wings of Gold, on the US naval air war in the Pacific devotes whole pages to fabrications from folks claiming to have
been involved in actions they were no where near, performing feats of daring-do that never happened. Checking
facts would have prevented mistakes. Maybe Green should have looked a little deeper.

I'll be the first to admit I'm not the brightest bulb in the chandelier, so maybe someone else ought to run the
numbers and see how they come out. I'm willing to be wrong, but I just don't see how this flight could have
happened the way it is described. Nor does the historical record bear it out. I'd suggest that there may have
been a plan to try to see how close they could get. A plan with a lot of wishful thinking involved (not unusual
for some of those folks, especially as events became more and more unpleasant and more and more desperate
for them) that never got off the ground when the rational thinkers on the pointy end of the stick looked at it.

Regards,

Rich

Excellent analysis Rich - and to add to the equation, load another 10,000 pounds as a payload - and take 10,000 pounds of fuel off the table for the 'nuke' part of the story.

 

[Kiwikid]

Now that you've read Richard Leonard's figures... here's the true figures:

The Ju-390 used six BMW 801E engines which were identical to the BMW 801D except the E version was geared for better performance at altitude. The 801E was geared for lower engine revolutions.

In all other regards one can consider fuel consumption the same or slightly superior fuel consumption for the 801E. The E version had about a 100hp superiority at altitude.

The BMW 801E also had a boost function for take off, by injection of a water methanol mixture into the left supercharger inlet. This could only be used for 10-15 minutes. Only at these boost settings does the fuel consumption rise to 221 US Gals PH.

The B-29 which had 80% higher wing loading and less power, took 25 minutes to reach 20,000ft.

So run six engines at boost for 15 minutes is 331.5 US gallons (1989lb)

Normal max operating consumption is 90-103 US Gal per hour per engine so let's keep climbing for another 10 minutes at 90 US Gal/engine...(54lb)

Okay so to reach 20,000ft the Ju-390 needed 25 minutes roughly and about 2043lb of fuel.

In cruise the BMW801D in long range cruise setting used 45-55 US Gals per hour at around 1600-1700 RPM per engine. I suspect with the 801E engine it used only 45 US Gal, but hey let's be pessimistic and call it 55 US Gal/hr per engine time 31 hours flying is 61,380lb plus 2,043 lb to reach 20,000ft for a grand total of 63,423lb. The Ju-390 is known to have capacity for 65,000lb fuel.

It had a maximum take off weight of 166,100lb and an empty weight of 86,900lb. Subtract empty weight and maximum fuel weight together (151,900lb) from 166,100lb still leaves the aircraft with a whopping payload capability of 14,200lb over 6,000 nautical miles.

If it was impossible then maybe Richard Leonard needs to come back here and share with us why not. It follows that if the Ju-390 with 10,380 horsepower could not do the mission then neither could the B-29 with 8,800 hp but then we all know the B-29 not only could, but did.

In fact it is already known that Richard Leonard's figures are bogus because Ju-390 test pilot Hans Pancherz has already published the Ju-390 range payload figures. Pancherz also flew to South Africa in his Ju-390.

 

[Soren]

Gotta agree with Kiwikid

 

[drgondog]

Now that you've read Richard Leonard's figures... here's the true figures:

The Ju-390 used six BMW 801E engines which were identical to the BMW 801D except the E version was geared for better performance at altitude. The 801E was geared for lower engine revolutions.

In all other regards one can consider fuel consumption the same or slightly superior fuel consumption for the 801E. The E version had about a 100hp superiority at altitude.

The BMW 801E also had a boost function for take off, by injection of a water methanol mixture into the left supercharger inlet. This could only be used for 10-15 minutes. Only at these boost settings does the fuel consumption rise to 221 US Gals PH.

The B-29 which had 80% higher wing loading and less power, took 25 minutes to reach 20,000ft.

So run six engines at boost for 15 minutes is 331.5 US gallons (1989lb)

Normal max operating consumption is 90-103 US Gal per hour per engine so let's keep climbing for another 10 minutes at 90 US Gal/engine...(54lb)

Okay so to reach 20,000ft the Ju-390 needed 25 minutes roughly and about 2043lb of fuel.

I see 221x 6 engines for .5 hr + 331.5 gallons x 6.5 pound/gal = 2154.. plus 90x 6 x 1/6 hr x 6.5 = 585 pound

= 2739 pounds and 421 gallons

In cruise the BMW801D in long range cruise setting used 45-55 US Gals per hour at around 1600-1700 RPM per engine. I suspect with the 801E engine it used only 45 US Gal, but hey let's be pessimistic and call it 55 US Gal/hr per engine time 31 hours flying is 61,380lb plus 2,043 lb to reach 20,000ft for a grand total of 63,423lb. The Ju-390 is known to have capacity for 65,000lb fuel.

Where is the reference? however if so that means 9579 gallon to start a journey at altitude perhaps 70 miles along the way.

If the Ju 390 could cruise optimally at 200 mph in full fuel and crew but no payload, which I doubt, then it could at 55gph fly another 29 hours.

It had a maximum take off weight of 166,100lb and an empty weight of 86,900lb. Subtract empty weight and maximum fuel weight together (151,900lb) from 166,100lb still leaves the aircraft with a whopping payload capability of 14,200lb over 6,000 nautical miles.

No way the Ju 390 combines Maximum Range with Maximum Payload. No way the cruise speed for optimal range is much above 50% of it's max speed empty

It doesn't often work that a payload can a.) be max with max fuel, b.) that a Bomb load in the case of this type aircraft is the same as the max payload.

I know of zero cases where an aircraft carries a max payload for its tested maximum range, nor carry max load to its tested max ceiling.

This link is the only one I have found referencing the better performing 801E but at same time indicates that the MAX range is in Recce configuration for 6000 miles and 32 hours, that the max bomb load is 3,968 pounds and the Max payload is 22,000 pounds.

But nowhere does it state any combination of load, to cruise speed to range. If the above figures are correct then the optimal cruise for the zero payload (implied Recce) is 6000/32 = 188mph average. I would believe that.

[]www.warbirdsresourcegroup.org - Warbirds Resource Group - Error

If it was impossible then maybe Richard Leonard needs to come back here and share with us why not. It follows that if the Ju-390 with 10,380 horsepower could not do the mission then neither could the B-29 with 8,800 hp but then we all know the B-29 not only could, but did.

The aspect ratio of the Ju 390 was around 9.9 and the aspect ratio for the 29 was 11.5 - the Ju 390 had six engines to the B 29 four.

For the B-29, the normal combat ops radius with 20,000 pounds of bombs was 3250. The maximum airspeed was 355mph (light load) and the max ceiling for 20,000 pound bomb load was 33,000 feet. The cruise speed for the bomb load and radius was 220 mph

All of this IMPLIES a much cleaner airframe for the B-29 over the Ju 390.

In fact it is already known that Richard Leonard's figures are bogus because Ju-390 test pilot Hans Pancherz has already published the Ju-390 range payload figures. Pancherz also flew to South Africa in his Ju-390.

Because the B-29 could carry a 20,000 pound load farther than a Ju 390 could in Recce config (according to above link), was 40 mph faster and could climb to nearly 2x the ceiling of the Ju 390, I suspect it is safe to say two things.

1. The Ju 390 had a lot more drag than a B-29. Very unlikely that its loaded cruise speed was anywhere close to the B-29.
2. Its range with 20,000 pounds was far less than a B-29
3. Its endurance with 20,000 pounds was far less than 30 hours.

I might be driven to conclude that the Ju 390V2 could range out 3,000 miles and back if you could show that it could cruise at 200mph with fuel consumption of 50 gallons per hour at that speed... with no payload, just crew and fuel.

I'm don't know if it had an internal bomb bay. If not, then whatever you hang on the wings will take 10-20 mph off the optimal cruise.

Regards,

Bill

 

[Soren]

The bomber version of the Ju-390 had a bomb bay.

The range of the Ju-390 was 400 miles longer than the B-29's, and the Ju-390 could carry a larger payload as-well. The B-29 was faster and had a higher ceiling though.

The Germans did produce both an equal and superior bomber compared to the B-29 though. The Me-264 was the equal, being nealry as fast with less power, and a much longer range and slighty higher payload. Superior to both however was the He-277, with a very high ceiling, cruise speed, payload good range, plus a respectable 570 km/h top speed this was the most advanced bomber of WW2.

He-277

This a/c could be loaded to over twice its empty weight!

 

[pbfoot]

R Leonards makes perfect sense to me , you'd have to strip that Junkers down to the walls , remove all radios ,oxygen systems and safety equipment to cut down on the weight even find crew that were skinny . Just doing a simple D=RxT a 27hr trip at 210 mph for 6000mile+/- at his fuel rates not including the headwinds you'll get at some point

 

[drgondog]

R Leonards makes perfect sense to me , you'd have to strip that Junkers down to the walls , remove all radios ,oxygen systems and safety equipment to cut down on the weight even find crew that were skinny . Just doing a simple D=RxT a 27hr trip at 210 mph for 6000mile+/- at his fuel rates not including the headwinds you'll get at some point

Pb - at one time I looked for specs on the Ju 390 that were not speculation, and to this day I haven't found any load/speed/range data for either the A1 or A2. Too many people confuse Max Range, Max Payload, Max Ceiling data as one and the same test flight conditions.

Absent that data anything I say is pure speculation on my part.

I seriously doubt that either the Ju 390A1 or A2 could cruise an average of 180mph with just the fuel load of 10,000 gallons. If it could then it would have slightly more ferry range than the B-29 if you stripped the reserve from the published figure for the 29.

Speculatively I also doubt that either could range 3300 miles with a 20,000 pound bomb load, even if either one had internal bomb bays.. and so far I have only seen reference to wing racks for the 3900 pound bomb load/guided missle capability

 

[Kiwikid]

I was interested because of Bodo's short runway to discover the Ju-390's performance. Bodo was home to Ju-87 Stukas which were fighting a Russian invasion of northen Norway.

The airfield was built much like US airfields were in the Pacific from matting, but in this case planking over quite boggy flat ground.

To cut a long story short I was amazed to find that the Ju-390 for all it's size and weight had a ground footprint similar to a DHC-4 Caribou, a 19 seater Dornier Do-228, or less than the ground footprint of a DC-3 which could use Bodo. The Ju-390 had an ACN range of 3.5-3.7.

The B-29 in standard air at 120,000lb can take off over a 50 foot obstacle in 5,100 feet. The Convair B-36 at MTOW can take off in 1,500 metres (no screen obstacles).

The Ju-390 has superior power to weight ratio and less wing loading than either the B-29 or B-36.

In fact the Ju-390 has just 55% of the B-29's wing loading and just 73.4% that of the B-36. The Ju-390 has 85% better power to weight ratio than the B-29 and 14% better than the Convair B-36.

The B-29 had a total of 8,800hp, the B-36 had 21,000hp and the Ju-390 had 10,380hp.

One could fairly confidently predict therefore that the Ju-390 could lift off in less distance than the B-36 (1,500m) and nearer to the 1000 metres which a DC-3 is capable of. It's not entirely scientific, but I would not be surprised if a fully laden Ju-390 in standard conditions could take off in 1200-1300 metres.

 

[Kiwikid]

Pb - at one time I looked for specs on the Ju 390 that were not speculation, and to this day I haven't found any load/speed/range data for either the A1 or A2. Too many people confuse Max Range, Max Payload, Max Ceiling data as one and the same test flight conditions.

Operational notes for the Ju-390 including payload range charts, from one of it's test pilots, Han Pancherz have been published in a couple of books including the autobigraphy of Pancherz who lives in Barcelona. From time to time Pancherz gives interviews about the Ju-390 to Spanish newspapers.

If you're not prepared to accept the data from the aircraft's test pilot then you're unlikely to accept any amount of evidence.

Incidentally since you ask drgndog the Ju-390 had a service ceiling of 20,000 feet.

Where is the reference? however if so that means 9579 gallon to start a journey at altitude perhaps 70 miles along the way.

A any pilots will know the take off and climb are always the most thirsty part of a flight whether it's a WW2 Ju-390 or Boeing 737. Most aircraft burn a lot of fuel climbing to cruise altitude and then generally fuel flow reduces to around 30% but that is variable according to the type of aircraft and it's specific engines.

References ?
Because I don't speak German I have not read his autobiography, but there is a book called FlugPancherz. Pancherz's figures and charts are also published in "Target America, Hitler's plan to attack the United States" by James P Duffy, Pub 2004 by Greenwood Press ISBN 0275966844

There are numerous other references so I only refer you to those from the test pilots own notes.

Yes I fumbled some figures from the climb. As I recall when I calculated it I rounded some of the numbers because you can't be precise about the climb f you don't know the exact time to climb. In general my figures are more real than Leonards which I suspect are based on Kossler and Ott's figures.

55 US gals per hour is per engine incidentally in case that was not clear.

As a pilot drgndog I do understand the difference between long range cruise and economical cruise. I also understand the difference between ferry range and max payload range thank you.

Seek and ye shall find. The fuel consumption figures for BMW801 engines are well known and widely published for all to see.

 

[Kiwikid]

pbfoot wrote:

R Leonards makes perfect sense to me , you'd have to strip that Junkers down to the walls , remove all radios ,oxygen systems and safety equipment to cut down on the weight even find crew that were skinny . Just doing a simple D=RxT a 27hr trip at 210 mph for 6000mile+/- at his fuel rates not including the headwinds you'll get at some point

Well sad to say Richard leonard got the calculations grossly wrong because he assumed 150 US gals per engine for the cruise and then multiplied that by 6 engines.

The truth is that the true figure is 45-55 US Gals per hour x 6 engines.

You have to start with the right consumption assumption. Sorry couldn't resist that.

 

[pbfoot]

Well sad to say Richard leonard got the calculations grossly wrong because he assumed 150 US gals per engine for the cruise and then multiplied that by 6 engines.

The truth is that the true figure is 45-55 US Gals per hour x 6 engines.

You have to start with the right consumption assumption. Sorry couldn't resist that.

I used your numbers and did some quick math with the available weight , weight of gas and 55 gph per engine overall rounded off to take account of climb etc. Its all rough numbers but so would the flight planning be without proper consideration for winds aloft and other factors that would affect things the 390 wouldn't have knowledge of , considering it would be tough to climb over weather with the low service ceiling

 

[Kiwikid]

Hi Pb,

All I did was calculate take off and climb to 20,000ft and then the fuel needed for 31 hours of flight.

The endurance would easily permit a return Atlantic mission. Jetstreams would not figure much at 20,000 feet. I have to pop out for an appointment, but will be back later to discuss it.

There is a rumour which I am unable to substantiate that the flight may have been from Norway to Michigan then past new York on it's return to Mont de Marsan, but I can't contact the source for this.

 

[drgondog]

Operational notes for the Ju-390 including payload range charts, from one of it's test pilots, Han Pancherz have been published in a couple of books including the autobigraphy of Pancherz who lives in Barcelona. From time to time Pancherz gives interviews about the Ju-390 to Spanish newspapers.

If you're not prepared to accept the data from the aircraft's test pilot then you're unlikely to accept any amount of evidence.

Kiwi - data from a single source, and a personal one at that, unmatched by other sources would lead me to at least hold belief in suspension. I'm glad you aren't a cynic like me

Incidentally since you ask drgndog the Ju-390 had a service ceiling of 20,000 feet.

Yes, I believe that is what the link I posted said.. back to this later

A any pilots will know the take off and climb are always the most thirsty part of a flight whether it's a WW2 Ju-390 or Boeing 737. Most aircraft burn a lot of fuel climbing to cruise altitude and then generally fuel flow reduces to around 30% but that is variable according to the type of aircraft and it's specific engines.

I'm quite well aware of that, but thanks for helping me further understand. The fuel flow from max power to optimal cruise varies quite a bit. For a P-51D the max is around 240 Gallons per hour and minimum cruise fuel consumtion was approx 48gph at 18K/1800rpm and 23" for a combat load

References ?
Because I don't speak German I have not read his autobiography, but there is a book called FlugPancherz. Pancherz's figures and charts are also published in "Target America, Hitler's plan to attack the United States" by James P Duffy, Pub 2004 by Greenwood Press ISBN 0275966844

There are numerous other references so I only refer you to those from the test pilots own notes.

As a pilot though, you saw enough data to believe the claims? What was the test pilot's stated optimal cruise altitude and speed for the Ju 390? As a pilot you know that the best cruise is never at max altitude?



Yes I fumbled some figures from the climb. As I recall when I calculated it I rounded some of the numbers because you can't be precise about the climb f you don't know the exact time to climb. In general my figures are more real than Leonards which I suspect are based on Kossler and Ott's figures.

And why is that? Did Leonard fumble his figures also? And what assumptions that you made are any more valid than his. So far this whole discussion including mine, are laced with 'assumptions' - said assumptions leaning to one side or the other in the debate - but assumptions nevertheless?

55 US gals per hour is per engine incidentally in case that was not clear.

I believe you stated 45-55 as the BMW801E fuel flow for your assumptions. What is not clear are two factors not in your assumptions - first is the cruise speed at that fuel flow, the second is the rated altitude for best cruise efficiency

As a pilot drgndog I do understand the difference between long range cruise and economical cruise. I also understand the difference between ferry range and max payload range thank you.

Actually I wasn't directing that comment at you.

Seek and ye shall find. The fuel consumption figures for BMW801 engines are well known and widely published for all to see.

Back to your point about the Ju 390 ceiling at 20,000 feet.

As a pilot isn't it curious to you that an aircraft with greater horsepower and lighter wing loading than a B-29, as presented above....

but can barely climb to 60% of the ceiling of the higher flying, faster B-29 which has less power and a higher wing loading (according to the 'published data)?

As a pilot, wouldn't you want to know more about the flight test data gathered before an alleged flight to New York, so that you had a lot of cofidence in matching a landing on land with a take off on land?

Wouldn't you want to know the specific altitude and rpm and boost and fuel flow to optimize your range - and what that cruise speed was? And wouldn't you be more confident in your beliefs if you had that data?


I look at the widely varying data available on the Ju 390 and keep asking myself fundamental questions.

Why would an aircraft like this, with 6 x 2000 hp and a wing loading less than a B-29 attain such poor performance unless the aircraft was seriously dirty, aerodynamically speaking. Particularly when you have made the point that this engine was one of the very best the LW had in Hp/wt ratio and performed well up to 40,000 feet. So it couldn't be that the engines would not perform.

So either the specs as given are wrong, or the aircraft was an enormous hog and NEEDED that much hp just to get it to 20,000 feet.

As a pilot, what conclusions do you draw?

 

[pbfoot]

Hi Pb,
The endurance would easily permit a return Atlantic mission. Jetstreams would not figure much at 20,000 feet. I have to pop out for an appointment, but will be back later to discuss it.
.

That is an extrodinary time aloft if my recollection is correct I believe the record for that amount time aloft without refuelling goes to the CP 07 Argus at 31 hours using the same powerplants as the B29 but much uprated to 3700 hp and thats a record only surpassed by Bert Rutans Voyager

 

[Soren]

The ceiling of the Ju-390 was low because of the very poor high alt performance of its BMW-801 engines. At SL it climbed allot faster than the B-29.

Hence the short take off landing roll of the Ju-390 Kiwikid.

At any rate the He-277 was a much better bomber, with a payload capacity larger than that of the British Lancaster, an amazingly high service ceiling, cruise speed and a good defensive armament top speed, it was technically the best bomber of WW2.