FW 190G / A-10 in Aluminum

[Lrrr]

What if: the Red Baron had survived to be the equivalent, replacement or superior of Galland.  He therefore may have maintained a 'flying circus' like policy of avoiding camouflage as from a favorite quote attributed to him in a movie I saw, "I don't want them to be surprised; I want them to be afraid." 

How it started:
I've always been conflicted about why American piston-engined planes always seem to look beautiful even when they are a hot mess of exposed cooling packages (P51) or chin turrets (B24).  Whereas I should be more drawn to simpler lines and roundness of a radial-engined FW-190A or F.  Then recently it hit me: I've seen them all the American planes in their shiny bare aluminum oxide finishes.  In army green they start to lose their appeal (See P47 'razorback' in green.  Looks mean, but not what I'd call beautiful)  So there was only one thing to do... build a WHIF of a 190 Radial in Aluminum and see if it stacks up.

Not quite finished yet, but I'm pretty happy with the results in as much as for me, it confirms that Aluminum is the girl-next-door and that paint used to blend into surrounding has a too-much-makeup sort of affect on me.


https://drive.google.com/file/d/0BwkX5wIzRixATTl1RWstUWxrMDA/view?usp=sharing


That got me thinking that the non-painting of aluminum aircraft could influence a more or a simplification of manufacture policy.  In non-WHIF world, Tank did take several very successful stabs at it in designing the 190 in the first place.  Examples are "armament should be designed into the aircraft from the onset rather than an afterthought" and "a radial engine is less vulnerable."  In his analysis, Tank alone was able to predict the needs of the Luftwaffe better than, in some cases, the RLM. 

Therefore,in my WHIF, Richthofen approaches Kurt Tank early in the RLM proposal process and the two discuss exactly what the Luftwaffe needs in an aircraft.  Tank is honored and more than happy to oblige.  The two get on the topic of engines, and over drinks the two agree that not only is Tank on the right path with air-cooled radials (the Red Baron flew many rotary-powered aircraft in WWI) but that the industry should continue pushing this boundary.  While Tank has developed a relationship with BMW (out of necessity, since they were the only large radial at the time) von Richthofen is aware of several engine programs vying for Luftwaffe consideration.

The conversation goes to the effect of:  Richthofen: "I think there is much promise in air-cooled engines.  I was recently at the Deutz factory in Oberusel" and mentioned the work KHD was doing with 2-stroke diesels.  Kurt was not aware, and Manfred answers what he can, but sort of shrugged at Kurt's more detailed engineering questions. Kurt remains curious, and by the time the meeting ends, the two agree to visit the factory together.

In 1938, after the first test of the Dz 700 but before the first Dz 710 begins, Tank is instantly interested in the promise of a small-diameter radial, as the valving would not require large cylinder heads on a Schnurle ported 2-stroke.  In a side-bar with Richthofen, he acknowledges that such an engine in combat is a big gamble, but the rewards would be enormous.  Richthofen bets on his new colleague, and by the time the two leave the factory Richthofen is determined to change Deutz's direction away from a heavy liquid-cooled flat-16 bomber engine to a lightweight fighter engine radial. 

One of, if not the most critical bottleneck of the German aircraft industry (and undoubtedly contributing to the loss of the Luftwaffe) was engine production.  The BMW 801 is a beautiful engine, but it was rather heavy for an air-cooled radial and took significant time and marks to make.  This WHIF theorizes that a Schnurle engine would have significantly greater specific power at altitude and specific fuel consumption than the BMW 801. 

KHD takes up the task of scaling up the Dz700 and the Dz702 is born.  In order to keep the design simple, the 4.0L 700 gets bumped up to 16L and then made a twin-row (32L) engine.  The main drawback in tests of diesel radials in tests is harsh vibrations, and KHD's plan to eliminate that was the boxer-16 design in the 710. Having one piston in each row opposing each other directionally had a similar affect in the Dz 702. 

Unfortunately the project went past 1939 and Tank needed to get the project kicked off, so Tank's first prototypes flew with the BMW 139 and the 801.  Performance, even without Tank's original concept of an aerodynamic cowling, was good enough to make it very dangerous for the British, so while the Dz702 was still undergoing tests, the FW 190A was the first to challenge the Spitfire MkV.

While the successes of the 190A in 1941 allowed the Luftwaffe a brief respite, neither Tank nor Richthofen were prone to sitting on their haunches, and in 1941 the efforts to improve altitude performance were in full swing.  While BMW proposed a turbocharged 801 for the FW 190B-0 and B-1 prototypes, the materials needed for a high-temp turbocharger were in short supply and the B was temporarily abandoned, until KHD's impeccably timed announcement that their 702 was ready for flight testing. 

The valveless design relied on a weak supercharger to maintain proper cylinder flow, but a second centrifugal supercharger was added to the rear of the engine in similar fashion to that on the 801.  In order to speed up production, both the blower and supercharger were single-speed.  The blower provided adequate pressure at sea level but could not keep up with demand at high altitude.  Fearing their 2-stroke diesel would be anemic at high altitude (a cardinal sin for diesels since JUMO's claim to fame was that their 2-stroke diesels were at home at high altitude), they geared the supercharger for high-altitude and simply bypassed any overpressure at low altitude.  They justified the extra work the engine was doing because tests already showed fuel consumption around half of the petrol radial competition, and with twice the power strokes per revolution, they had room to spare on power, weight, and fuel consumption in order to get the high-altitude performance that was needed.

Dz702 specifications:
Weight 550kg
Power 1750ps at takeoff; 1550ps at  12000m
Diameter 44 in
Notes - significantly fewer man-hours to build than BMW 801
Drawbacks - smoke is choking at ground level.  Crews try to get clear of aircraft at startup time, and pilots compensate by carrying extra oxygen and using for an entire engine-on time out of the very real fear of diesel smoke getting in the cabin and asphyxiating the pilot.  Additionally, British pilots get used to the telltale sign of 190B pilots gunning the throttle when alerted and producing ample black smoke. 

The production FW 190B-3 and beyond maintained the cowl diameter and cooling fan arrangement of the A-series. Performance was dramatically increased over the A-series at altitude and was more akin to the D-series (which in this WHIF would remain prototype only). 

Performance notes:
-Top speed of 440mph at high altitude
-Improved climb and turning circle owing to engine wet weight reduced by nearly 500kg over the A or D series. A real handful for the P47 even up to 40,000 ft. 
-Greatly improved range on internal fuel 

This particular variant is the G, a long-range attack Dz 702 equipped variant based off of the F-series, and due to the reduced central mass and ample room in the cowl, more armament could be afforded closer to the centerline.  The cowl guns are replaced with the 20mm MG FF with 450 rounds per gun, and the inner wing stations are Mk103 30mm cannons with 90 rpg (as proposed on the A-10 version).  I used steel dowels for the cannon barrels. 

Its resting on the landing gear cut-outs because apparently Revell wants me to drill holes to mount, which I simply cannot do.  But in any case, here it is in its natural state, using its phenomenal rate of climb to take an unsuspecting tactical bomber by surprise from underneath, or gaining altitude after a strafing run far away from base.  You get a good sense of the increased size of the cannons from this picture.


https://drive.google.com/file/d/0BwkX5wIzRixAT0lXRFVxeTF6dU0/view?usp=sharing

Next step is to see how the long Ta 152H wing can be grafted onto an 'A-series' fuselage.  I'd like to see a long-wing radial more akin to the A-10 as a Dz 702 equipped Zerstorer.

[NARSES2]

Looks good, interesting reasoning as well 

[Captain Canada]

Looks really good !

[Lrrr]

Next step is to see how the long Ta 152H wing can be grafted onto an 'A-series' fuselage.  I'd like to see a long-wing radial more akin to the A-10 as a Dz 702 equipped Zerstorer.

I have begun the process of attempting to graft a Ta 152H wing to a FW 190A-8 fuselage.  I decided to start new since I didn't know how complicated the surgery would be and didn't want to ruin my 1:32 Revell A-8 (the "G" build from above).  Both are Dragon 1:48 kits. 

rough images of the early mockup.

https://drive.google.com/file/d/0BwkX5wIzRixAQWg5d1dKMlh2ZkE/view?usp=sharing

https://drive.google.com/file/d/0BwkX5wIzRixAamNfMkZiRTdNdDQ/view?usp=sharing

https://drive.google.com/file/d/0BwkX5wIzRixARUMwNkRGRmtEYU0/view?usp=sharing

I can report that the surgery is on the high end of what I had anticipated: I will have to pull the center-section from the 152H kit. 
I'm excited to move forward, though; I like the long wing and the radial nose.  I am not sure how the handling at high altitude would be affected by having the elevators so close to such a massive wing.  However, the nose is 'short' so it would not be the weight that required the tail to be extended, as on the 190D and 152C. 

[jcf]

Interesting.

The RW KHD engines for those interested:
https://oldmachinepress.com/2013/08/17/klockner-humboldt-deutz-khd-dz-700-dz-710-and-dz-720/

[rickshaw]

According to "A Famous Fighter Focke-Wulf fw190", the BMW-801 was only effective to about 23,000 feet, which is why in the Fw190C, they introduced a blower to the engine.  Unfortunately, due to a shortage of high temperature steels the blowers kept failing, which in turn is why an inline engine was introduced on the D and Ta152 fighters.

[Lrrr]

According to "A Famous Fighter Focke-Wulf fw190", the BMW-801 was only effective to about 23,000 feet, which is why in the Fw190C, they introduced a blower to the engine.  Unfortunately, due to a shortage of high temperature steels the blowers kept failing, which in turn is why an inline engine was introduced on the D and Ta152 fighters.

The FW 190C prototypes used experimental Turbocharger.  Indeed, turbochargers require high temperature metals for the turbine, since they are using exhaust heat and velocity to create boost for the engine.  The wartime materials shortage kept Germany in particular from acquiring the precious metal.

A blower on the other hand is a positive displacement low-pressure supercharger.  It's rather on the opposite end of forced induction from the turbocharger and is frequently called a 'Weak Supercharger'. 

Typical uses for the various types of superchargers are:

Blower: 1-8psi
Supercharger 4-20psi
Turbocharger 8-30 psi (30 being on the high end for a diesel engine, which can take higher pressures)

Blowers are typically mechanically simple devices and should be no less reliable than the superchargers already in use in Germany.  Also, one was used on the Dz700 prototype engine.  Creating a 2-stage supercharger incorporating a weak blower shouldn't have been too technically difficult. 

[wuzak]

According to "A Famous Fighter Focke-Wulf fw190", the BMW-801 was only effective to about 23,000 feet, which is why in the Fw190C, they introduced a blower to the engine.  Unfortunately, due to a shortage of high temperature steels the blowers kept failing, which in turn is why an inline engine was introduced on the D and Ta152 fighters.

The Fw 190C was also to have the Daimler Benz DB 603.

[wuzak]

According to "A Famous Fighter Focke-Wulf fw190", the BMW-801 was only effective to about 23,000 feet, which is why in the Fw190C, they introduced a blower to the engine.  Unfortunately, due to a shortage of high temperature steels the blowers kept failing, which in turn is why an inline engine was introduced on the D and Ta152 fighters.

The FW 190C prototypes used experimental Turbocharger.  Indeed, turbochargers require high temperature metals for the turbine, since they are using exhaust heat and velocity to create boost for the engine.  The wartime materials shortage kept Germany in particular from acquiring the precious metal.

A blower on the other hand is a positive displacement low-pressure supercharger.  It's rather on the opposite end of forced induction from the turbocharger and is frequently called a 'Weak Supercharger'. 

Typical uses for the various types of superchargers are:

Blower: 1-8psi
Supercharger 4-20psi
Turbocharger 8-30 psi (30 being on the high end for a diesel engine, which can take higher pressures)

Blowers are typically mechanically simple devices and should be no less reliable than the superchargers already in use in Germany.  Also, one was used on the Dz700 prototype engine.  Creating a 2-stage supercharger incorporating a weak blower shouldn't have been too technically difficult.

Blower is often used as a generic term for supercharger, whatever form that may take.

In terms of pressure, it is better to talk in terms of pressure ratios.

As the compressors used in WW2 aircraft turbochargers were of the centrifugal type, the same as used for most big ww2 piston engines, it is unlikely that they could provide a higher pressure ratio. Most WW2 turbos had a single stage compressor, and only a few experimental turbos had 2 stages, which would allow for a higher pressure ratio.

On the other hand, several engine makers used two stage systems - including those which used turbochargers. Rolls-Royce, Pratt & Whitney and Jumo all had 2 stage mechanical superchargers.

A Merlin 45 could maintain +12psi boost (26.7psi MAP) to 18,000ft, while a Merlin 61, with its 2 stage supercharger, could maintain +15psi (+29.7psi MAP) boost to 23,500ft. They did this by throttling the intake, otherwise the supercharger would develop more boost than the engine could handle.

In American turbocharged installations of WW2 the turbo's job was to make the engine think it was at sea level. It compressed air at altitude so that it was at sea level pressure. The supercharger integral with the engine, which most big aero engines of WW2 had, provided the boost above atmospheric pressure.

I'm not sure if German turbos followed the same principle or actually provide boost above sea level atmospheric pressure.

As regards the Dz 702, I'd suggest that 32l is not enough to give the power you are suggesting. It would probably need to be half as big again, at least.

[rickshaw]

According to "A Famous Fighter Focke-Wulf fw190", the BMW-801 was only effective to about 23,000 feet, which is why in the Fw190C, they introduced a blower to the engine.  Unfortunately, due to a shortage of high temperature steels the blowers kept failing, which in turn is why an inline engine was introduced on the D and Ta152 fighters.

The Fw 190C was also to have the Daimler Benz DB 603.

Correct.  My error, i actually meant the Fw190B variant which had the BMW801 with a Turbo-supercharger.

[jcf]

When dealing with a 2-stroke diesel (and some 4-stroke) a blower is often simply that,
and is not specifically a supercharger (as the term is generally used), rather it is used to
aid/improve scavenging, however in some the same mechanism can perform as both
a scavenging blower (exhaust valves/ports open) and a supercharger
(exhaust valves/ports closed).

Roots type blowers are most common and in most turbo-supercharged 2-stroke diesel
installations they are the engine stage with the centrifugal turbo-charger blowing
through them.

So, the as proposed by Lrrr low-pressure blower/supercharger combo is possible, however
as it would be a mechanical supercharger rather than a turbo-charger it is going to exact
a price on total engine hp as driving the supercharger always saps power.

[Lrrr]

When dealing with a 2-stroke diesel (and some 4-stroke) a blower is often simply that,
and is not specifically a supercharger (as the term is generally used), rather it is used to
aid/improve scavenging, however in some the same mechanism can perform as both
a scavenging blower (exhaust valves/ports open) and a supercharger
(exhaust valves/ports closed).

Roots type blowers are most common and in most turbo-supercharged 2-stroke diesel
installations they are the engine stage with the centrifugal turbo-charger blowing
through them.

So, the as proposed by Lrrr low-pressure blower/supercharger combo is possible, however
as it would be a mechanical supercharger rather than a turbo-charger it is going to exact
a price on total engine hp as driving the supercharger always saps power.

Yes,

For the purposes of this WHIF this is what I was going for.  If turbochargers are not viable for Germany at this time, then the assumption is that a mechanical positive-displacement 'blower' keeps the gases flowing correctly through the Schnurle ports.

Parasitic losses considered acceptable due to the 2x the power-strokes per turn of the crank and reduced 'base' fuel consumption of the engine.  Even with the dual mechanical supercharger stages, assumption is 2-stroke diesel still maintains excellent high-altitude power. 

Per OldMachinePress (thanks to joncarrfarrelly for posting the link):

The Dz 700 had a diameter of around 38 in (1 m) and weighed only around 120 lb (55 kg). A blower (weak supercharger) forced air through manifolds in between and then into the cylinders.

Not much to go on technically, but I wanted to do something WHIF-fy with this interesting concept.

Cheers.

[wuzak]

The Rolls-Royce Crecy program started life as a 2 stroke Diesel.

I think their solution would work for the Dz 702. That is, instead of having a blower and a supercharger, the Crecy just used the supercharger to provide scavenging of the exhaust as well as providing boost. It is a simpler and lighter solution.

The Crecy used a very high bypass ratio - which was enabled by the direct injection design. That meant that a significant proportion of air from the compressor was just pumped out the exhaust. The bonus of this was that the exhaust gas temperature was lowered which allowed a turbine (in the Crecy's case a power recovery turbine) without the exotic materials, though Rolls-Royce probably used the same materials as was being used on their Whittle design.

As a Diesel, the Dz 702 would have lower exhaust temperatures anyway, so turbocharging would not be as much of an issue for that engine as it was for the larger petrol engines. The lack of high temperature alloys would be less of a problem.

[Lrrr]

The Rolls-Royce Crecy program started life as a 2 stroke Diesel.

I think their solution would work for the Dz 702. That is, instead of having a blower and a supercharger, the Crecy just used the supercharger to provide scavenging of the exhaust as well as providing boost. It is a simpler and lighter solution.

The Crecy used a very high bypass ratio - which was enabled by the direct injection design.

As a Diesel, the Dz 702 would have lower exhaust temperatures anyway, so turbocharging would not be as much of an issue for that engine as it was for the larger petrol engines. The lack of high temperature alloys would be less of a problem.

in my knifing of my Ta 152h and 190A models I did accidentally create a rounded gap on the bottom cowl.
I think I might be able to add a large single turbocharger exhaust port. 

[wuzak]

Thought this may have been of interest to you:

https://oldmachinepress.com/2016/03/24/fkfs-gruppen-flugmotor-a-c-and-d/

The first model was able to produce 1970hp and then 2170hp when switched to direct injection.

It was longer than the BMW 801, but of similar outside diameter.

Basically 4 Hirth HM 512s, the wight would have been around 1000-1100kg (the HM 512 weighed 270kg).