WWII MISTERIES: What happened with the JU390? (1 Viewer)

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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.
 
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%.
 

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?
 

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

Anybody know the cruise speed ?
 
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..
 

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'?
 
Soren said:
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.
Click to expand...

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

Anybody know the cruise speed ?
Click to expand...

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?
 
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 ?
 
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.
 

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?
 
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...
 
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