WWII MISTERIES: What happened with the JU390?

[Soren]

Perhaps we need to look at the P-47's service ceiling and compare it to the FW-190 A-9 for you to understand ?

The P-47 is turbo-supercharged fighter with a higher wing power-loading than the FW-190A, yet it still has a higher ceiling.

Again ENGINE PEFORMANCE at altitude is the reason behind the difference in service ceiling.

 

[Soren]

Btw,

4 x 2,200 = 8,800 HP

6 x 1870 = 11,220 HP

That's barely a 22% difference in power.

Have no clue how you got that to be 40%.

 

[drgondog]

Perhaps we need to look at the P-47's service ceiling and compare it to the FW-190 A-9 for you to understand ?

Perhaps you need to state what the BMW801E rated hp is for rated boost as a function of altitude to make me understand?

From Wright Pat Flight Test of P-47D-10 with P&W R2800-63 the following maximum Hp was achieved at the following

SL 2200hp@56" boost
20000 2325hp@56"
33000 [email protected]
38000 1550hp@39

So, for comparable boost what are the comparable figures for the 801E?

You keep slinging insults Soren because you can't show the data to back up your statements. Stop the insults, start the facts? I can own up to being wrong but it won't be because you can not help being rude.


The P-47 is turbo-supercharged fighter with a higher wing power-loading than the FW-190A, yet it still has a higher ceiling.

Allegedly the BMW801E is the high altitude improved version of the D-2, but all you do is talk about 'well known high altitude issues with the 801E.
I think we are still waiting to see those well know issues from a source other than your written word?

Where is the comparison you made between the Fw 190A-9, one with D-2 and one with E? Is that another 'well known' statement or do you have the facts? Facts would include Chart or Report by either LW or FW for boost, fuel type, weights as a function of altitude.

Again ENGINE PEFORMANCE at altitude is the reason behind the difference in service ceiling.

Why, yes I believe you are right, although apect ratios, power loading, wing loading are important factors?

Facts, reports, flight tests - you apparently were wrong about the BMW 801D-2 being used on the Ju 390.

You have yet to show a bomb bay for the Ju 390A1 (or V1 whichever was actually built)

You have yet to demonstrate the performance chart for the 801E in any form to use as comparison for a polite discussion on why the Ju 390 had a low service ceiling in comparison with the more heavily wing loaded B-29.

Now, I haven't seen the power charts for the R-3350-29A either. All I have for it are from Joe Baugher's website which gives 2200hp at Take Off power and 2300 at Max Power for 25,000 feet.

If you could prove that the Hp for the BMW 801E was 1800hp or less at say 15,000 feet and down to about 1200hp each at 18,000 feet we might be on our way to understanding why the Ju 390 couldn't 'get it up'.

By extrapolation however, the Fw 190A-9 with the BMW801E under those performance conditions would be sorely pressed to make 25,000ft ceiling.

This is speculation, I don't have facts on the 801E. Apparently you don't either but that doesn't stop you from drawing conclusions?

 

[drgondog]

Btw,

4 x 2,200 = 8,800 HP

6 x 1870 = 11,220 HP

That's barely a 22% difference in power.

I was wrong on my source. I checked two others which gave 1970hp rating - but didn't specify Take Off, WEO, boost or whatever.

www.warbirdsresourcegroup.org - Luftwaffe Resource Center - Junker Ju 290

This alleges the 801E on the version of the Ju290 it was used on performed to 1970hp. I have seen as low as 1770 as high as 2300 but no other data with respect to boost, altitude, etc.

So that is 34%, not 40%, not 22%

Soren - the key fact to bring your thesis into credibility is simple - the 6 x BMW 801E must deliver less hp at 19,600 ft ceiling than the 4 R-3350-23 at 33,000 ft ceiling for the B-29A for equivalent Max Gross Take Off weights - which is where our W/L calculations rest

I Have no clue.

Now please demonstrate the 'severe power loss of the BMW801E' with facts rather than statements?

With the Ju 390 ~15% advantage in W/L for Max Gross Weight you would have to be delivering significantly less than 1500 hp at 19,600 feet to not be able to climb higher. At 1533 hp for each of the 6 engines it should be able to exceed the B-29 for rate of climb at 25,000ft based on Baugher's data.

Is that your thesis?

 

[Soren]

LoL, you're the one not providing any facts Bill, not me! And your ongoing accusations of me not providing any facts and your continuous suspicion is what makes me turn rude towards you, cause like most people I don't take kindly to being slapped in the face.

But show me your sources which state that the Ju-390 V1 or V2 was equipped with the BMW-801E engine. The A-1 (Which was never built, only designed) was the version meant to have the E series engine.

Anyways..

Here's the performance gain of using the BMW-801F (Superior to the 801E at all alts) over the BMW-801D-2: (From FW Leistung chart already posted Shall I post it again to easen your suspicion ?)

FW-190 A-9, Service Ceiling: 10.8 km
FW-190 A-8, Service Ceiling: 10.6 km

A whopping 200m in difference!

With the BMW-801F it takes the A-9 19.6 min to reach 10km, the poor high alt performance significantly decreasing performance above 23,000 ft.

Yeah, the BMW-801E certainly was going to help allot on high alt performance

 

[pbfoot]

Soren and kiwi you giuys are making unsubstantiated claims 32 hours aloft in the 390 is that number actually proven or is it should be able to number . The record for unrefuelled flight prior to Rutans Voyageur was 31 hours and that was with a combat load and 2 crews .

 

[Soren]

I haven't claimed anything Pbfoot. The proven range was 9,700 km. What'ever that is in hours I don't know and I have never claimed to know either.

 

[pbfoot]

I haven't claimed anything Pbfoot. The proven range was 9,700 km. What'ever that is in hours I don't know and I have never claimed to know either.

187 knots at 32 = 6032nm

 

[Soren]

Where did you get the 187 knot figure from ?

 

[Soren]

The cruise speed might have been 400 km/h, which would equal 24.25 hours.

Anybody know the cruise speed ?

 

[Soren]

Bill,

If you cease being suspicious I'll cease being rude, deal ?

I really hate being rude or having to get rough, I loath it, but it's hard not to when provoked. I like you Bill, I have from the start and still do, but we have a habbit of provoking each other (Similar mindset perhaps). Anyway lets quit it now.

You might be busy with other things, which is why you overlooked some of the things I posted (There are after-all things in real life to attend to), so perhaps I shouldn't have been as harsh as I was but my points still stand; The ceiling of the Ju-390 was as low as it was because of the poor high alt peformance of the BMW-801 engine (Wether it be th D-2 or E, doesn't matter)

Anyway this is a truce offer, so we can continue the debate in a orderly fashion and not ruin a thread.

This is for every'ones best..

 

[drgondog]

LoL, you're the one not providing any facts Bill, not me! And your ongoing accusations of me not providing any facts and your continuous suspicion is what makes me turn rude towards you, cause like most people I don't take kindly to being slapped in the face.

But show me your sources which state that the Ju-390 V1 or V2 was equipped with the BMW-801E engine. See your own reference below!The A-1 (Which was never built, only designed) was the version meant to have the E series engine.Your reference below states just the opposite

The V1 V2 were equipped with the D-2 engines, the A-1 was supposedly to be equipped with the E engine.




Actually it is more fun to post YOUR comments and sources, but NONE of the references below, including Yours mentions any engine configuration except the BMW801E.. do you a 'thread' there?, :

You said -
"The V1 V2 were equipped with the D-2 engines, the A-1 was supposedly to be equipped with the E engine."

You pointed to this as a link

Junkers Aircraft of WWII

It linked to this site

Junkers Aircraft of WWII

Which in turn referenced this

Ju290/390 Aircraft
Ju290V1/V2 with 4 x 1150kW BMW801MA (ex Ju90V11 and Ju90V13), Ju290 prototypes, 1942
Ju290A1 transporter aircraft with 4 x 1150kW BMW801L2, 9 built
Ju290A3 long range surveyer with 4 x 1150kW BMW801D/G and larger fuel capacity
Ju290A4 as A3, only productional differences, BMW801D2, five aircraft built
Ju290A5 as A4 for naval operations, 11 built, 3 aircraft were later transfered to Lufthansa
Ju290A7 as A5, with better radar equipment, BMW801G and longer fuselage
Ju290A8 as A5 with better radar equipment, two built, but unfinished at end of WWII
Ju290A9 as A5 for transporter missions.
Ju290B surveyer aircraft, with 4 x BMW801E, derivated from Ju290A7, with pressured cabin in 1944
Ju290C projected high altitude transporter
Ju290D projected high altitude bomber
Ju290E projected night bomber aircraft
Ju290Z projected "Zwilling" mistel aircraft of 1942

Ju390A1 transporter aircraft with 6 x BMW801E, one built in 1943, second not completed.

To help find what you posted as Your reference carefully note the underlined comment in that post of the Ju 290/390 series?



So, Soren - Your reference to me doesn't even mention V1 or V2

Next - here is one of the sites I looked at - I used underlines to help you find the data..

uboat.net - Technical pages - Junkers Ju 290 and Ju 390
stating

Specifications
Junkers Ju 390V2

Six 1970hp BMW 801E radial engines Wing span 50.32m, length 33.6m Empty weight 36900kg, max. take-off weight 53112kg Max. speed 515km/h at 6200m, cruising speed 357km/h. Max. range 9700km.

Armament: Two dorsal gun turrets, each with a MG151, and one MG 151 in the tail. Aft and front MG131s in the gondola, and two MG131 beam guns.

Next:

WRG - Luftwaffe Resource Group - Junkers Ju 390

Leading to:

Type: Long Range Bomber or Reconnaissance aircraft.
Origin: Junkers Flugzeug und Motorenwerke AG
Models: V1 to V3 and A-1
Crew: N/A
First Flight: Prototypes only
Final Delivery: None
Number Produced: V1 and V2 Only

--------------------------------------------------------------------------------
Engine:
Model: BMW 801E
Type: 18-Cylinder two-row radial
Number: Six Horsepower: 1,970 hp--------------------------------------------------------------------------------
Dimensions:
Wing span: 165 ft. 1 in. (50.30m)
Length: 112 ft. 2.5 in. (34.20m)
Height: 22 ft. 7 in. (6.89m)
Wing Surface Area: N/A

Weights:
Empty: 81,350 lb. (36,900 kg)
Loaded: 166,448 lb. (75,500 kg)
Performance:
Maximum Speed:
Clean: 314 mph (505 kph)
With Max. Eternal Weapons: 267 mph (430 kph)
Initial Climb: N/A
Service Ceiling (Typical): N/A
Range in Recce configuration:
6,027 miles (9700 km)
Endurance in Recce configuration: 32 Hours

--------------------------------------------------------------------------------
Armament:
Eight 20mm MG 151.
Eight 13mm MG 131.

Payload:
Transport (V1): 22,046 lb. (10,000 kg)
Bomber (V3): 3,968 lb. (1800 kg)

Avionics:
FuG 200 Hohentwiel Radar.

So, who is confused? Further, what is an unimpeachable source for data on the Ju 390? And you think I'm "suspicious". I'm hurt that you would think I would question anything you say, especially when using your own source?

Anyways..

Here's the performance gain of using the BMW-801F (Superior to the 801E at all alts) over the BMW-801D-2: (From FW Leistung chart already posted Shall I post it again to easen your suspicion ?)

FW-190 A-9, Service Ceiling: 10.8 km
FW-190 A-8, Service Ceiling: 10.6 km

A whopping 200m in difference!

Do you sense 'circular' movement here? You posted this earlier, I asked for data source/link, etc showing this comparison and providing details, you bring the same two lines back including the "A whopping 200m in difference!"

Does this meet your high standards of referenceable data in a debate?

With the BMW-801F it takes the A-9 19.6 min to reach 10km, the poor high alt performance significantly decreasing performance above 23,000 ft.

Is there anything in your words that a person could parse through and find relevant BMW801E performance Hp as a function of boost and altitude so we can get back to the question "Why is the Ju 390 service ceiling so LOW?

Yeah, the BMW-801E certainly was going to help allot on high alt performance

You roll your eyes often. Good simple facts would serve you better.

So far you are quite skilled at slinging insults and writing words. You have demonstrated that you will say one thing and reference a link that directly contradicts not only what you said but used as support for what you said!!

Why?

Soren - if you don't have BMW 801E performance data for Hp at 19,600 feet to help us understand if a.) the Ju 390 was underpowered at this altitude, or b.) had a reasonable power reserve at that altitude - we will never be able to determine analytically what it's capabilities were.

Soren, if you don't have Specific Miles per Gallon of Fuel at Best Cruise settings (as a function of altitude and payload) for the Ju 390/BMW 801E system - we will never be able to realistically determine its range potential!

If we don't stop waving around and pointing to contradictary web sites to prove statements about the Ju 390, what sources CAN be believed?

If we don't stop making bold statements like "everyone knows" and one can't point to a reference which at least proves "Someone knows", why are You believeable in this debate?

The crux to believing ANYTHING about the Ju 390 other than it doesn't exist anymore, is a.) reliable specs about the aircraft or version if more than one was actually built and flown. That would include fuel capacity, Performance data citing Top Speed, Top Speed with a load, Cruise Speed (with same load) for max endurance, Cruise Speed (with same load) for max range..

or b.) Drag figures for the airframe plus comprehensive performance data for the BMW801E engines plus correct fuel capacity and Gross Weight at takeoff including fuel and payload for the Gross Weight in question.

In other words, what do you KNOW versus what do you 'think'?

 

[drgondog]

I haven't claimed anything Pbfoot. The proven range was 9,700 km. What'ever that is in hours I don't know and I have never claimed to know either.

Ah, there seems to be a difference in "proven" versus "Claimed" versus "stated" versus "I think" versus "this is what the link said" versus.. well you get the idea. So, what exactly is "proven" relative to the Ju 390 (any version)

Unless it is Flight test data from a reliable source (like the Luftwaffe) that demonstrates reasonable veracity it wouldn't be "proven" to me.

You have alternatively claimed "everyone knows the 801E had altitude performance problems", you have claimed that the Ju 390 used 810D-2's, when your source said it was 801E's, you have claimed "the Ju 390 had bomb bays" when I posted my only reference of bomb carrying ability was an external load of 3900 pounds.

So, what is your definition of "proven"?

 

[Soren]

I know the BMW-801D-2 has poor high alt peformance, I know the BMW-801F which featured better performance than the BMW-801E across the board didn't prove much of an improvement, providing an extra 200m in service ceiling over the BMW-801D-2.

Because of this we can quite safely assume that the engines were the reason behind the low service ceiling, I mean what else could it be Bill ? Seriously.

 

[drgondog]

The cruise speed might have been 400 km/h, which would equal 24.25 hours.

Anybody know the cruise speed ?

No, Soren. This has been one of the key issues in this debate. No one seems to have a clue regarding a.) Actual verified specifications for maximum fuel capaciy, b.) cruise speed for maximum endurance and the specific fuel consumption at that speed as a function of payload, c.) cruise speed for maximum range and the specific fuel consumption for that speed as a function of payload, d.) performance of the BMW801E as a function of Hp, boost, specific fuel consumption, etc as a function of altitude.

To summarize - nobody "knows" anything about this aircraft. Everybody has OPINIONS. Few OPINIONS have been validated as yet.

There is ZERO fact base on BMW 801E performance

There is ZERO fact base concerning any version of the Ju 390 versiosn with respect to detail design specifications

There is Zero fact base concerning any flight test data for the Ju 390.

I have HEARD from Kiwi that the former Test Pilot included tables in his book. I have not seen them, so far nobody has presented them, so far nobody has authenticated them, so far nobody has produced Luftwaffe data on them.

There is ZERO fact base concerning any flight that 'travelled" 6200 miles or stayed aloft 32 hours.

Does this accurately summarize what we KNOW about the Ju 390?

Do you wonder why I am suspicious? or wonder why I can't understand why you aren't suspicious?

 

[pbfoot]

Where did you get the 187 knot figure from ?

rate= distance over time

 

[Soren]

You'd need to know either the time or cruise speed along with distance to establish this Pbfoot.

So where did you get the 187 knot figure from ?

 

[Soren]

Bill,

No we don't have the specific power chart for the BMW-801E, but we do know that the BMW-801F which was a superior engine across the board didn't improve high alt performance by any significant margin, providing a mere 200m extra in service ceiling.

In short knowing the exact performance of the BMW-801E is irrelevant to this discussion.

 

[drgondog]

I know the BMW-801D-2 has poor high alt peformance, I know the BMW-801F which featured better performance than the BMW-801E across the board didn't prove much of an improvement, providing an extra 200m in service ceiling over the BMW-801D-2.

Because of this we can quite safely assume that the engines were the reason behind the low service ceiling, I mean what else could it be Bill ? Seriously.

Soren - by the same logic LW leaders could not believe a single engine fighter like the Mustang, with extremely high performance, could escort daylight bombers past Berlin..

They had to accept the proof of their eyes, but only when they understood the drag characteristics and internal fuel capacity did understanding become complete. Realistically they knew the fuel capacity but had no reason to believe the range was comparable to the P-38

So, no I don't accept that the engines were the problem until someone shows me a BMW 801E power and fuel consumption profile that demonstrates that the 801E had less than 800 Hp at 25,000 feet and less than than 1000 hp at 20,000 ft. For 15% less W/L than a B-29 that might represent a power range that is inadequate to get to 20,000 feet.

Further complicating the question is the continuous statements that the "810E was the high altitude version of the 801D". What kind of High altitude versions of any high performance Radial had 1/2 the SL Hp at 20,000 feet? or even a reduction of Hp at 20,000 feet (from sea level).

Why do you believe it?

 

[Soren]

Btw, the figures from U-boat.net are interesting, noting a top speed of 515 km/h at 6,200m. Now top speed is never anywhere close to the service ceiling so somehing aint right.

Sources are very different on this bird...