Focke Wulf light fighter

[spicmart]

The Fw190A was smaller than a P-51D - there's really not much you can remove wing or fuselage wise and still have it be airworthy.

Its dimensions were smaller. Empty weight was the same though with 3200 kg.
Structurally the Fw 190 was just quite heavy for a reason.
Tank designed her as a cavalry horse.

 

[z42]

It's dimensions were smaller. Empty weight was the same though with 3200 kg.
Structurally the Fw 190 was just quite heavy for a reason.
Tank designed her as a cavalry horse.

Also a question of where it's going to be used. AFAIU LW was often operating from makeshift air bases, often with poor runways. Meanwhile half of southern England had been paved over with long and smooth runways.

 

[spicmart]

Also a question of where it's going to be used. AFAIU LW was often operating from makeshift air bases, often with poor runways. Meanwhile half of southern England had been paved over with long and smooth runways.

That is of course an advantage for the Allies.
No wonder why the tailwheels of German fighters were so big comparatively.

 

[GrauGeist]

As before - engine/powerplant was the heavy brute here, so replace it with DB 605 in order to be able to think about smaller & lighter wing, U/C etc.

The 801 was not all that much of a boat-anchor.
The Fw190A-3 weighed almost 6,400 pounds empty, the Fw190A-8 weighed 7,650 pounds empty and the Fw190D-9 weighed just under 7,700 pounds empty with it's Jumo213 engine.

The Jumo213 weighed just over 2,000 pounds dry which was about 200 pounds lighter than the 801 (dry).

The DB605 was close to 400 pounds lighter (dry) than the 213, but when is all.said and done, making the 190's airframe smaller is not going to provide much of an advantage. Especially in reducing it's wingspan any more than the A series' 34 feet, as this would handicap it at altitude, where it was needed to counter Allied bomber escorts.

 

[tomo pauk]

Okay, let's put the Fw 190 on a diet.
F-W says that the BMW 801 powerplant will be heavier by 456 kg than the DB 605A powerplant for their spin-off of the Fw 187. Divided by two, difference of 278 kg. The 801s on the Fw 187 weight breakdown notes that two 801s will weight 2108 kg, with trapped fuel an oil. Armor is noted as weighting just 39 kg for the twin 801 installation, ie. ~20 kg per engine, however on the Fw 190 one engine there was 78 kg or armor for the oil system. If the 187 was projected to have the same armor as the Fw 190, the weight difference would've been up by ~120 kg.
The weight breakdown for these projects also notes the lower weight needed for the wing and U/C for the DB version, FWIW.

Back to a single 801 vs. 605A.
278 + 58 (= 78-20) = 366 kg weight reduction. The 605 allows for the motor cannon, so the MK 108 is installed instead of the cowl MG 131s and outer MG 151s. Less weapon drag even than what the D-9 had. Main gain is reduction of weapon-related weight (guns + ammo + mounts etc), circa 300 200kg, at least going by this table. Or probably 250 150 kg in case the cowl guns are the MG 17s? Compared with Fw 190A-6, were down by some 600 500 kg of take off weight, clean, mostly thank to the engine change - not a minor save vs. a 4100 kg fighter.
Now undercarriage - our brave new fighter will not be lugging around heavy bombs, so introduce a lighter U/C, with smaller wheels and a bit shorter legs. Instead of 258 kg, we might probably go down to 200 kg? Yes, I'm shamelessly copying what the NAA did here.
A 15% weight reduction allows us to cut the wing area by 15%, while keeping the wing loading the same. I'd try to get rid off the central - ie. the thickest - wing section by some 12-13% worth of span. Wing assy of the 190A8 weighed 475 kg, so here we can also save another 50-60 kg, and some drag, too (wing-related-drag on the Fw 190D-9 was significant 37% total drag - a new spanking low-drag wing on the 190/152 line certainly had a place here).

We'd be getting the lower wing- and weapon-related drag even when compared with the 190D-9 here, and probably the lower cooling drag. Weight save will be amazing vs. Antons and Doras, and wing loading will not be worse. Mileage will be much better.

edit: haven't accounted for the MK 108 + it's ammo weight in the 1st go; still a 600 kg decrease vs. the 190A-6 with lighter wing accounted for

 

[spicmart]

Okay, let's put the Fw 190 on a diet.
F-W says that the BMW 801 powerplant will be heavier by 456 kg than the DB 605A powerplant for their spin-off of the Fw 187. Divided by two, difference of 278 kg. The 801s on the Fw 187 weight breakdown notes that two 801s will weight 2108 kg, with trapped fuel an oil. Armor is noted as weighting just 39 kg for the twin 801 installation, ie. ~20 kg per engine, however on the Fw 190 one engine there was 78 kg or armor for the oil system. If the 187 was projected to have the same armor as the Fw 190, the weight difference would've been up by ~120 kg.
The weight breakdown for these projects also notes the lower weight needed for the wing and U/C for the DB version, FWIW.

Back to a single 801 vs. 605A.
278 + 58 (= 78-20) = 366 kg weight reduction. The 605 allows for the motor cannon, so the MK 108 is installed instead of the cowl MG 131s and outer MG 151s. Less weapon drag even than what the D-9 had. Main gain is reduction of weapon-related weight (guns + ammo + mounts etc), circa 300 kg, at least going by this table. Or probably 250 kg in case the cowl guns are the MG 17s? Compared with Fw 190A-6, were down by some 600 kg of take off weight, clean, mostly thank to the engine change - not a minor save vs. a 4100 kg fighter.
Now undercarriage - our brave new fighter will not be lugging around heavy bombs, so introduce a lighter U/C, with smaller wheels and a bit shorter legs. Instead of 258 kg, we might probably go down to 200 kg? Yes, I'm shamelessly copying what the NAA did here.
A 15% weight reduction allows us to cut the wing area by 15%, while keeping the wing loading the same. I'd try to get rid off the central - ie. the thickest - wing section by some 12-13% worth of span. Wing assy of the 190A8 weighed 475 kg, so here we can also save another 50-60 kg, and some drag, too (wing-related-drag on the Fw 190D-9 was significant 37% total drag - a new spanking low-drag wing on the 190/152 line certainly had a place here).

We'd be getting the lower wing- and weapon-related drag even when compared with the 190D-9 here, and probably the lower cooling drag. Weight save will be amazing vs. Antons and Doras, and wing loading will not be worse. Mileage will be much better.

Thanks, tomo!

But the armament with an MK 108 and two MG 17 is kind of meh. I know, not seriously . Late war in a dogfight you're at a disadvantage with the ballistics of the cannon and two pop guns.
According to your table an MK 108 weighs 82.2 kg with mounting. Say it carries 70 to 80 rounds which are 90 - 100 kg roundabout.
Together with the MG 17s' 50 kg it would be the same total weight as two MG 151/20 which I would rather keep.
Or maybe borrow some B-20s from the Soviets which weigh just 25 kg each . But German 20 mm mine shell are the most destructive.

To give it better turn performance and stay agile at high alt I wouldn't cut wing area too much, 1 to 1.5 sqm maximum.

Can you tell why the D-9 wing was so draggy and how this could be remedied?

 

[tomo pauk]

But the armament with an MK 108 and two MG 17 is kind of meh. I know, not seriously . Late war in a dogfight you're at a disadvantage with the ballistics of the cannon and two pop guns.

One MK 108, two MG 151/20s.
We get rid of the wing MG 151/20s, as well as of cowl guns, be these the MG 171s or 131s.

Or maybe borrow some B-20s from the Soviets which weigh just 25 kg each . But German 20 mm mine shell are the most destructive.
To give it better turn performance and stay agile at high alt I wouldn't cut wing area too much, 1 to 1.5 sqm maximum.

Speed-up the MG FF/M and we're in the ballpark.
Actually, for the Eastern Front, three belt-fed MG FF/Ms, each firing at 600 rd/min (vs. 520 as it was the case) will represent a convincing firepower; wign FF/Ms go outside the prop arc, of course. Methinks that 17 sq m is okay for the 190 lite.

Can you tell why the D-9 wing was so draggy and how this could be remedied?

I really don't know. The wing-related drag of the D-9 was a greater percentage of the drag than of the A-8 (~37 vs. ~34%) because the total drag of the D-9 was lower - absolute drag value of the wing-related drag was the same for the D-9 and A-8.
Interestingly enough, British were of opinion that Fw 190A wing-related drag was just 26.2% - lowest figure for any 1-engined fighter per their data.
Granted, the two tables don't use exactly the same system of drag analysis tabulation.

Usage of thinner profile might've still helped, like the outer 70% of the wing that Ta 152 used, or the outer 80% of the big-wing Fw 190 prototype. More advanced solution would've been the laminar-flow wings - nick the airfoil coordinates from the Me 309 perhaps?
Take a look at outer parts of the Fw 187 wing, for something 'classic'? See what the He 280 or Me 262 used, and copy the airfoil from there?

 

[spicmart]

One MK 108, two MG 151/20s.
We get rid of the wing MG 151/20s, as well as of cowl guns, be these the MG 171s or 131s.

Speed-up the MG FF/M and we're in the ballpark.
Actually, for the Eastern Front, three belt-fed MG FF/Ms, each firing at 600 rd/min (vs. 520 as it was the case) will represent a convincing firepower; wign FF/Ms go outside the prop arc, of course. Methinks that 17 sq m is okay for the 190 lite.

I misunderstood the armament. For me 3 x 20 mm MG 151/20 would be optimal. Enough MV. Would be around 45 kg less than with the 108.

Usage of thinner profile might've still helped, like the outer 70% of the wing that Ta 152 used, or the outer 80% of the big-wing Fw 190 prototype. More advanced solution would've been the laminar-flow wings - nick the airfoil coordinates from the Me 309 perhaps?
Take a look at outer parts of the Fw 187 wing, for something 'classic'? See what the He 280 or Me 262 used, and copy the airfoil from there?

Not sure if they could have gotten the weapons bay-undercarriage-wing profile-positioning right with a thin laminar profile wing.
The regular 190 wing is rather thick up front which could to house the gun and the UC.
I wouldn't adopt anything from Messerschmitt fighters, too risky. Would rather trust an inhouse FW design or ask Heinkel or NAA for that matter...
The Fw 187 had the same airfoil as the 190, hasn't it?

So a 3.5 ton fighter.
Kind of.

 

[tomo pauk]

Not sure if they could have gotten the weapons bay-undercarriage-wing profile-positioning right with a thin laminar profile wing.
The regular 190 wing is rather thick up front which could to house the gun and the UC.

Laminar-flow wings were thick on the Mustangs (16% at root) and P-63. Lightweight Mustangs were still with the thick profile (15%).
Note that Fw 190 had no problems in housing even the MK 108 in the thinner, outer part of the wing, and I've suggested going with the less bulky U/C for the lw 190s.

I wouldn't adopt anything from Messerschmitt fighters, too risky.

Why do you think so?

The Fw 187 had the same airfoil as the 190, hasn't it?

I don't have firm data right now.

 

[z42]

Okay, let's put the Fw 190 on a diet.
F-W says that the BMW 801 powerplant will be heavier by 456 kg than the DB 605A powerplant for their spin-off of the Fw 187. Divided by two, difference of 278 kg. The 801s on the Fw 187 weight breakdown notes that two 801s will weight 2108 kg, with trapped fuel an oil. Armor is noted as weighting just 39 kg for the twin 801 installation, ie. ~20 kg per engine, however on the Fw 190 one engine there was 78 kg or armor for the oil system. If the 187 was projected to have the same armor as the Fw 190, the weight difference would've been up by ~120 kg.
The weight breakdown for these projects also notes the lower weight needed for the wing and U/C for the DB version, FWIW.

Back to a single 801 vs. 605A.
278 + 58 (= 78-20) = 366 kg weight reduction. The 605 allows for the motor cannon, so the MK 108 is installed instead of the cowl MG 131s and outer MG 151s. Less weapon drag even than what the D-9 had. Main gain is reduction of weapon-related weight (guns + ammo + mounts etc), circa 300 200kg, at least going by this table. Or probably 250 150 kg in case the cowl guns are the MG 17s? Compared with Fw 190A-6, were down by some 600 500 kg of take off weight, clean, mostly thank to the engine change - not a minor save vs. a 4100 kg fighter.
Now undercarriage - our brave new fighter will not be lugging around heavy bombs, so introduce a lighter U/C, with smaller wheels and a bit shorter legs. Instead of 258 kg, we might probably go down to 200 kg? Yes, I'm shamelessly copying what the NAA did here.
A 15% weight reduction allows us to cut the wing area by 15%, while keeping the wing loading the same. I'd try to get rid off the central - ie. the thickest - wing section by some 12-13% worth of span. Wing assy of the 190A8 weighed 475 kg, so here we can also save another 50-60 kg, and some drag, too (wing-related-drag on the Fw 190D-9 was significant 37% total drag - a new spanking low-drag wing on the 190/152 line certainly had a place here).

We'd be getting the lower wing- and weapon-related drag even when compared with the 190D-9 here, and probably the lower cooling drag. Weight save will be amazing vs. Antons and Doras, and wing loading will not be worse. Mileage will be much better.

edit: haven't accounted for the MK 108 + it's ammo weight in the 1st go; still a 600 kg decrease vs. the 190A-6 with lighter wing accounted for

What's the timeline here? Is this a replacement for the FW190A or FW190D?

If the former, the 605A was introduced in 1942, a bit later than the FW190A was introduced historically. Though AFAIU the mountings for the 601 and 605 were identical, so one could start with the 601 and later the 605 upgrade would be straightforward. Particularly if the cowling isn't as tight as on the 109 so you can avoid all the bulges. Another problem is that the Mk 108 was introduced in 1943. Start with a Mg 151/20 motor cannon?

If the latter, what is the power/weight comparison between this suggested lightweight FW190 and doing a similar lightweighting exercise except using the Jumo 213?

 

[tomo pauk]

What's the timeline here? Is this a replacement for the FW190A or FW190D?

Replacement for the Bf 110 used in the East and Med, plus for the Bf 109, plus something that Axis allies can actually get?
It has better potential for long range than the Bf 109, since it has more internal fuel, even before we add some extra fuel behind the pilot.

If the former, the 605A was introduced in 1942, a bit later than the FW190A was introduced historically. Though AFAIU the mountings for the 601 and 605 were identical, so one could start with the 601 and later the 605 upgrade would be straightforward. Particularly if the cowling isn't as tight as on the 109 so you can avoid all the bulges. Another problem is that the Mk 108 was introduced in 1943. Start with a Mg 151/20 motor cannon?

Oh, I'm avoiding the bulges by nixing the cowl guns
Yes, if this aircraft is early enough, it will probably sport 'just' 3 20mm cannons.

If the latter, what is the power/weight comparison between this suggested lightweight FW190 and doing a similar lightweighting exercise except using the Jumo 213?

For the 190 suggested above by your's truly, we look at a 3500 kg aircraft, that has 1350 PS at 5.7 km (fully rated DB 605A = Oct 1943 and on; no ram) = 2.59 kg/PS.
The 190D-9 as-is was 4270-4300 kg, at 5.7 km it had 1550 HP = ~2.76 kg/HP.

Using the big and heavy Jumo 213 or DB 603 is probably going contrary to the wishes for a lightweight Fw 190, since the weight spirals up, not down.

 

[spicmart]

Laminar-flow wings were thick on the Mustangs (16% at root) and P-63. Lightweight Mustangs were still with the thick profile (15%).
Note that Fw 190 had no problems in housing even the MK 108 in the thinner, outer part of the wing, and I've suggested going with the less bulky U/C for the lw 190s.

Now that you mention it, I recall that they even mounted huge MK 103s into the wing roots of a Ta 152 or Fw 190D.

Why do you think so?

An ironic swipe at Messerschmitt design bureau as I often got the impression that their developments were less practically sound and reliable than e.g. comparable Focke Wulf's or Heinkel's. I just didn't insert a smiley.




The lw 190 would climb a bit slower than a Me 109 with the same propulsion as weight is a tad higher whereas it should be faster because of less radiator configuration drag.
The D-9, though a bigger airframe, was less draggy than a 109G IIRC. Not sure about the 109K.

 

[tomo pauk]

An ironic swipe at Messerschmitt design bureau as I often got the impression that their developments were less practically sound and reliable than e.g. comparable Focke Wulf's or Heinkel's. I just didn't insert a smiley.

Okay, roger that.
OTOH - MTT's wing design on the Me 163 and 262 was probably the best in the world? Even the wing of the Me 309 receives probably more credit than the complete Me 309 fighter. A new book is worth looking at, FWIW.

The lw 190 would climb a bit slower than a Me 109 with the same propulsion as weight is a tad higher whereas it should be faster because of less radiator configuration drag.

The lw 190 will also be with a bigger wing, so at higher altitudes it might've climbed at least as good? Note that 'my' 190 is also with much better firepower than the ordinary 109G-6, and with more fuel.
The clean 109G-2 was probably the best of the lot, but once they started adding lumps & bumps on the 109, and without improvements to cancel that, it's drag figures indeed went to the toilet facility.

The D-9, though a bigger airframe, was less draggy than a 109G IIRC. Not sure about the 109K.

109K incorporated what was supposed happen in 1943, like the streamlined cowling (that were in some late 109Gs, however) for MG 131s, better tail and tail wheel that was now again retractable, as well as wheel well covers. Net result being ~20 km/h gain vs. the 109G-10 with the same engine.

FWIW, the MG 131 installation seems to lower top speed by 10 km/h vs. the MG 17 installation on the 190, at least per this.

 

[spicmart]

Okay, roger that.
OTOH - MTT's wing design on the Me 163 and 262 was probably the best in the world? Even the wing of the Me 309 receives probably more credit than the complete Me 309 fighter. A new book is worth looking at, FWIW.

Wow! Will definitely order this one as for the limited print. The Me 309 is a gorgeous piece.
Someone wrote he back-ordered it but Morton's says it is coming this month?
Amazon would be better for me as I'm on a budget though I would rather like to support the authors.

109K incorporated what was supposed happen in 1943, like the streamlined cowling (that were in some late 109Gs, however) for MG 131s, better tail and tail wheel that was now again retractable, as well as wheel well covers. Net result being ~20 km/h gain vs. the 109G-10 with the same engine.

There had been a heavily modified Me 109K which was estimated to be a full 60 km/h faster (though Messerschmitt was notoriously known for overestimating figures) but was rejected for being too much of effort to alter production:

Much improved Me 109K?

The following is an excerpt from "Messerschmitt Flugzeug Profile Bf-109 G/K" by Manfred Griehl. It is originally German so I translated it into English: Two month before delivery of the Me 109K-4 in October 1944, proposals for improving the K were given from Erprobungsstelle Rechlin to the...

ww2aircraft.net

FWIW, the MG 131 installation seems to lower top speed by 10 km/h vs. the MG 17 installation on the 190, at least per this.

Always helpful that you provide sources.



Would an lw 190 be structurally strong enough to perform manoeuvers a regular 190 was known for?

 

[tomo pauk]

There had been a heavily modified Me 109K which was estimated to be a full 60 km/h faster (though Messerschmitt was notoriously known for overestimating figures) but was rejected for being too much of effort to alter production:

You will understand me being skeptical on that.
For my money, a Bf 109 aimed for 750+ km/h would've need a brand new wing and radiator set-up (both were getting too draggy for the speed levels hoped for), indeed the newer cockpit canopy (with a more slanted windscreen), and probably the DB 605L in the nose.

Always helpful that you provide sources.

Not a problem.

Would an lw 190 be structurally strong enough to perform manoeuvers a regular 190 was known for?

It would've been even stronger, since most of the weight reduction was from change/removal of the non-structural members, like powerplant group and guns/ammo; wing is smaller, too.

 

[spicmart]

You will understand me being skeptical on that.
For my money, a Bf 109 aimed for 750+ km/h would've need a brand new wing and radiator set-up (both were getting too draggy for the speed levels hoped for), indeed the newer cockpit canopy (with a more slanted windscreen), and probably the DB 605L in the nose.

Makes sense.

 

[spicmart]

It would've been even stronger, since most of the weight reduction was from change/removal of the non-structural members, like powerplant group and guns/ammo; wing is smaller, too.

DB 605D or L would have made this 190 a really nice performer. Is there a credible source for the top speed Me 109K-14 anyway?

 

[tomo pauk]

DB 605D or L would have made this one a nice performer.

Of course.
With the 605AS and 605D it would've hopefully been in-between the 109G-10 and K-4, and what is more important, in the ballpark of the Merlin Mustang speed-wise, while climbing better due to the lower weight.

 

[spicmart]

Of course.
With the 605AS and 605D it would've hopefully been in-between the 109G-10 and K-4, and what is more important, in the ballpark of the Merlin Mustang speed-wise, while climbing better due to the lower weight.

II assume with a laminar flow wing profile it could be faster than a K-4 or K-14 with the respective engine.

 

[z42]

Would an lw 190 be structurally strong enough to perform manoeuvers a regular 190 was known for?

The historical FW190 already had an issue with wing flexing at high G moving the lift distribution outward, thus countering the wing twist and leading to very harsh stall characteristics.

Unsure whether saving structural weight in the wing would have been wise.

http://www.wwiiaircraftperformance.org/mustang/Lednicer_Fighter_Aerodynamics.pdf

Of course.
With the 605AS and 605D it would've hopefully been in-between the 109G-10 and K-4, and what is more important, in the ballpark of the Merlin Mustang speed-wise, while climbing better due to the lower weight.

The Mustang was probably a quantum leap ahead of any other single engine fighter in terms of the drag coefficient (see above pdf for an overview and references to primary data). To an extent you can overcome that with more hp which the late war 605's running on C3 should do, particularly at low altitude where the lack of a two stage supercharger won't hurt as much. Enough to overcome the difference in drag?