Sten SMG aircraft: productionized aircraft part 2, the what if

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The idea behind showing the weights was that both alternatives would wind up heavier than the Hurricane after the engine swaps. The Bristol could windup over 500lbs heavier (crediting the Bristol with over 100lbs for it's propeller).
We have to believe that a smaller wing (by 30sq ft) Bristol that is 2-300lbs heavier than the 'equivalent' Hurricane is actually cheaper to build.
Wiki seems to be wrong (and may be in conflict with itself) and first flight of the unarmed prototype was in Dec of 1937. Armed 2nd prototype was flown in March of 1938 at which time the Hurricane has been issued to the first squadron and two more were equipped by the end of June 1938.
Chances of hitting 340mph with the existing landing gear????
I have serious doubts about the F.5/34 hitting the claimed speed as so much about it seems wrong. That or everybody (every British and American aircraft company) should have been given an F.5/34 for study.
the P-36B with a modified R-1830 engine giving 950hp at 17,000ft was only able to hit 317.5 mph compared to claimed 316mph at 16,000ft for the F.5/34 with 840hp.
Or compare to the MC.200 that did 313mph at 14,800ft on 840hp, granted the MC.200 engine cowl/fuselage was a bit of a clown show but the wing was 50 sq ft smaller than the F.5/34 and had fully retractable landing gear instead of semi/retractable.
Find another radial engine fighter with so little power with such obvious drag producing features that went that fast.
Ki-43 and A6M2 were similar in size, wing area, weight and had about 100 more HP, the Ki-43 was slower and A6M2 was faster.
If the F.5/34 truly was that fast the British lost the recipe for "Gofast paint" and/or "anti-gravity" paint.
tomo pauk said:
Granted, MB.2 needs to be designed with the Merlin in the nose from the get go, if it is to be accepted into production in a timely manner.
Click to expand...
Also needs a new tail
This was the modified tail after the first/s flights

Now ask the Air Ministry to risk an Merlin engine in that thing with the vertical stabilizer cut down to the top of the fuselage?
It took the designers at least one more try after the photo and maybe two give up on the idea of using using the rear fuselage side area for stabilization.
 
Shortround6 said:
The idea behind showing the weights was that both alternatives would wind up heavier than the Hurricane after the engine swaps. The Bristol could windup over 500lbs heavier (crediting the Bristol with over 100lbs for it's propeller).
Click to expand...

Thank you.

Shortround6 said:
We have to believe that a smaller wing (by 30sq ft) Bristol that is 2-300lbs heavier than the 'equivalent' Hurricane is actually cheaper to build.
Click to expand...

You have me scratching my head about me claiming that Gloster would've been cheaper to build than the Hurricane.

Shortround6 said:
Chances of hitting 340mph with the existing landing gear????
Click to expand...

Very much imperfect landing gear didn't prevent P-40 being as fast as Spitfire on same HP, eventually hitting 420+ mph. Or indeed Re.2001 hitting 340 mph with their take on how to make imperfect landing gear.
You will note that I'm not expecting that Merlin Gloster is an all-singing all-dancing fighter, but something that might be churned out faster than Spitfire while not having the 30-40 mph disadvantage already against the 109E, as it was the case with Hurricane I.


Looking at all the dead wood that was churned out in thousands in the UK from 1938-42, the Merlin-powered MB.2 is unicorns and rainbows.
 
tomo pauk said:
You have me scratching my head about me claiming that Gloster would've been cheaper to build than the Hurricane.
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Well. This is a thread on "Sten/productionized" aircraft
You may not have made the claim but it seems to part of the discussion.
Cheaper to build gets thrown around a lot. But we have no idea how to figure it out except by using generalities. The Hurricane was supposed to be easy to build.
Hawker could use some existing "tooling" on the Hurricane. Tooling covers a bunch of things, They had the equipment to make tube framework. So even if none of the tubes were the same size/length as a previous plane it wasn't hard to make longer tubes, the ends were formed into square fittings to slip into the joints. another company may use welded tubing. Hawker may not have had very many welders (both machines and trained workers). There were steel tube and aluminum tube. Hawker used a square box section and faired out the surfaces of the fuselage with extra parts. Somebody else may have used more tubes than 4 to round out the fuselage shape and used fewer/smaller extra fairing pieces. The variations could be rather numerous and we haven't even gotten into monocoque fuselage yet
rough estimate was sometimes done by weight of the airframe and skipping over the labor but we know accurate that is. See cost of the F6F in later versions. One of the cheapest fighters on a per pound basis of WW II.
tomo pauk said:
Very much imperfect landing gear didn't prevent P-40 being as fast as Spitfire on same HP, eventually hitting 420+ mph. Or indeed Re.2001 hitting 340 mph with their take on how to make imperfect landing gear.
Click to expand...
Well, there is imperfect (not streamlined well) landing gear an imperfect (streamlined moderately well) landing gear.
One thing I have always wondered about was the change in the P-40 from the P-36/Re. 2001 landing gear.
The last two used pretty much the same landing gear with a 1/2 wheel cover and the wheel horizontal in the wing and the P-40s used no wheel covering at all. Since the XP-40 was built using a P-36 airframe it had a the wheel covers. (they also changed the doors around a bit) but Curtiss had to know what the wheel covers were worth when they built the P-40s.
Perhaps when you get to the rear of the wing the airflow is disturbed enough that the lack of wheel cover is minor compared to lack of wheel cover in the 1/3 of the wing?
The Gloster was in a different catagory.


You have over 1/2 the wheel hanging out the bottom of the wing. Shades of the P-35
Forget about the fairing under the wing hiding the strut/s. A wheel like that is probably about 3rd worst shape you could use on an aircraft. Somewhere below cube and round ball.
Yes it could be fixed, just turn the wheel as it retracted just like the P-36. But even the disturbed airflow in the back of the wing theory doesn't cover wheel sticking out into undisturbed air.

My question is how did this thing ever post the numbers reported for it?
I am doubting if you would get the 30-40mph speed change you are hoping for. A Hurricane under test in June of 1940 was good for 310-316mph under best conditions. Service squadrons could/would be a bit lower.
We are depending a lot on the slightly smaller wing and the very slight change in airfoil to gain a lot of advantage over the Hurricane.
tomo pauk said:
Looking at all the dead wood that was churned out in thousands in the UK from 1938-42, the Merlin-powered MB.2 is unicorns and rainbows.
Click to expand...
Well, in the fall of 1939 they had fixed (maybe) the issues with the tail and rudder. They still needed to fix the other controls. Yes the British were turning out a lot of dead wood, or even dead twigs, but most of the really bad stuff was not sucking up Merlins. 1939-40 was when they were build the shadow factories for Merlin's and they needed every Merlin they could get to stuff into planes that were supposed to using Hercules engines. Yes you could swipe the the engines from the Defiants but you needed to make that decision in early 1939 or even 1938. The first Defiant squadron was being issued aircraft in Dec 1939 which was only few months after they gave up on trials of the MB.2 so unless the development of the MB.2 is changed by several years it is a no go. B-P got the first contract for the Defiant (87 airframes) in April of 1937. First production plane was in June of 1939 and testing of the service plane/s vs prototypes took a while.
 
The first hurdle is the airframe is only part of the total cost.

The USAAF did some cost of aircraft studies, The AT-6 airframe in the 1943/44 period was around 52.4% of total cost, the combined P-39, 40, 43, 47, 51 and 63 airframe costs for the same time were 53.6%. The P-38 airframe 65.8% and even with all the electronics the P-61 airframe was 62.75%.

Next hurdle is performance, the faster the more the airframe surface condition becomes important, a propeller driven aircraft has to move from fixed pitch to constant speed, overall precision of build becomes more important, control surfaces need to go from fabric to metal covering, add heating, oxygen, pressurisation, supercharging and so on. Ability to carry external loads? Range? Sophisticated and/or mass tactics require good multi channel radios.

The US did a number of studies and while it is clear engineering for ease of production was important the big savings are if you place large orders of unchanged designs, as that enables worker experience to build up and justifies more and better tooling. And that applies across the board, airframe, engine, armament, electronics and so on.

The first P-63 was costed at over 40 worker hours per airframe pound, the 3000th around 1.2 worker hours per pound.
10th production P-47D around 9 hours per pound, 6,000th around 0.6 hours per pound.
Dallas P-51 5th aircraft 6 hours, 110th 2.4 hours, 2,000th 1 hour, 5,000th 0.38 hours
Curtiss P-40 9th aircraft 9 hours, 100th 3 hours, and after the 900th went up for a while then steadied at around 1.5 hours.

The A-26 requirement was from 1940, prototypes ordered in mid 1941, next generation to the A-20, Douglas would be expecting mass production and have the knowledge from the increase in A-20 and C-47 production. 3rd aircraft 16 worker hours per pound, 18th 6 hours, 110th 2.8 hours, 400th 1.6 to 1.8 hours, 1,000th 1.4 hours.

The A-20 was 13th 4.5 hours, 100th 4 hours, 400th 2.1 hours, 1,000th 1.4 hours.

Ford Willow Run is the poster for maximum tooling (though not costs as lots of tooling was unable to recover costs), 3rd B-24 at around 21 hours per pound, 8,000th around 0.35 hours per pound. At B-24 airframe 5,000 San Diego was 0.6 hours per pound, Ford under 0.4 hours.
 
Alternative Bristol aircraft, using 1 engine instead of two:
- 1/2 Blenheim - size of SBD, but mid-wing shape like the SBN, powered by Pegasus engine, 4 x 250 lbs bombs in the under-fuselage recess; still reasonably fast for pre-1939 conditions, equally (un)suited for going against LW contested airspace later as it was the original Blenheim, but useful on less 'hot' theaters
- 1/2 Beaufort - size between Henley and Battle, preferably again with Pegasus in the nose - again no great shakes when it is about flying in the tooth of LW (both fighters and Flak), but it might've been useful with proper escort and in less contested airspace, and indeed above water and away from shoreline
Both of these would've looked well with R-1820 or R-1830 in the nose, too.

- 1/2 Beaufighter - size of the Hawker Hotspur (that itself was a combination of Hurricanes wing - wing area figure in the Wikipedia article is wrong - and a more substantial fuselage that was originally supposed to support a turret as it was the case with Defiant); I like the cooling system, too bad it wasn't employed on the Hurricane. Hercules in the nose (so much for the cooling system), four cannons in the wing, wing size between Hotspur and Henley so more fuel can be packed.

<takes cover>
 

This is a very important observation, and it was even coined "Wright's law" after someone called Theodore Paul Wright working for Curtiss-Wright (AFAIU no relation to the founder of the company). Experience curve effects - Wikipedia

Or more generally learning curves: Learning curve - Wikipedia

Applies to a lot more than producing war materials, as well, but I digress.
 
INCOMMING!!!

Stick the Pegasus in the nose, change the belly to hold two bombs side by side.

Recall from mid east, put better cowling on the nose as shown in photo
next project.

Fit a real propeller and bulge the bomb bay, done.
 
German transports:
- Ju 52 with just one egine, preferably the Bramo 323P (with 2-speed S/C); mostly cargo-carrying version. Talk a more modern looking An-2 Colt, or indeed a more capable version of the original Ju 52
- Ju 52 with two engines
 
tomo pauk said:
German transports:
- Ju 52 with just one egine, preferably the Bramo 323P (with 2-speed S/C); mostly cargo-carrying version. Talk a more modern looking An-2 Colt, or indeed a more capable version of the original Ju 52
- Ju 52 with two engines
Click to expand...
Germans should have stopped flogging the nearly dead horse in 1937-38.

You can reduce the drag just a bit by getting rid of the engines but you aren't going to get a 1200hp airplane off the ground in the distance that you can get a 2100hp engine in......unless you make it smaller and carry less cargo/passengers in which case you need more airplanes/pilots and actual cost goes up.

An-2 Colt carries roughly 2/3rds the passengers about 84% as far and is going 10mph slower (?) it may be a bit better than the JU-52 but it is tight.
It also has a few drawbacks of it's own. Like it is a biplane.

Note the flying wires. which have to be adjusted periodically. RAF called the men who did that 'riggers' which is separate from regular mechanics although I am sure there some men who could do both.


Not sure about how easy the Ju-52 was to build.

9 (?) full length spars, all the V struts and the stingers.
And that airfoil is fat. It may have been high lift for take-off landing but it was FAT.

You can trace much of the construction/aerodynamics back to 1919. It was not just "stick a fork in it done" but it was scrape the bottom of the pot done.

I have put forward the HP Harrow and Bristol Bombay before as examples. You don't need a DC-3 to beat the Ju-52.
 
GrauGeist said:
The Ju52/3 was pretty much a low-wing version of the Fokker F.VII or Ford's 2/3/4/5-AT series.
Click to expand...
It was sort of a giant version of the F 13


That dates back to 1919.
Junkers was always all metal.
Fokker used fabric-covered steel-tube fuselage and a plywood-skinned wooden wing.
Ford used all metal but a different form of wing construction although not all pictures of restorations seem to show the same things (?).


There were about 48 Hamilton metal planes built in the late 20s in the US


the advantages of the corrugated metal panels were appreciated at the time (strength for weight) but once they started looking at faster airplanes the drag penalty started overcoming the weight penalty (stronger frame work to support the skin). More powerful engines allowed for the trade-off.
 

Yes, agree. Of course, "cheaper to build" also encompasses labour (translated as labor) as you have pointed out. Hawker's workforce, having used the same knowledge and techniques to build on the production line hundreds of Furies, Harts, Audaxes, Hinds and so forth would have found the Hurricane little different and so would have not had as much retraining and there would not have been as much interruption on the production floor as there would have if the workforce was beginning an aircraft that used very different construction methods, like, for example, Westland's workforce going from the Lysander and Wallace to the Whirlwind. This will have no doubt aided the time taken to get the Hurricanes rolling off the production line, which would have reduced time and therefore cost.

Shortround6 said:
Junkers was always all metal.
Click to expand...

Indeed. Junkers was a firm that utilised a simple premise and stuck with it. Junkers saved on structural weight given the engines available to the firm at the time by stiffening the structure with external corrugations. Internally, the wings and fuselage did not have as much structural framework as other manufacturers used. In the wings, the number of evenly spaced ribs was less than most other aircraft, with structural strength gained from the external skin pieces fastened together and braced by the corrugations. The same applied to the fuselage. Even the Ju 87 was built this way despite not having the external corrugations. The external skin bore much of the structural loading as the internals comprised fewer frames and longitudinals than in more commonly applied metal structures. Junkers aircraft were constructed like the buildings and sheds they resembled...
 
tomo pauk said:
German transports:
- Ju 52 with just one egine, preferably the Bramo 323P (with 2-speed S/C); mostly cargo-carrying version. Talk a more modern looking An-2 Colt, or indeed a more capable version of the original Ju 52
- Ju 52 with two engines
Click to expand...

Didn't we have a thread recently were we discussed a better German transport? I think desirable qualities would be
  • 2 engines. Germany was, perhaps, in general lacking a cheap and robust radial in the 1000-1200 hp range that could be mass-produced, like the R-1820 or R-1830. In lieu of that, Jumo 211 would do.
  • Construction using steel and plywood, to save the oh-so-precious aluminum for combat aircraft. Junkers went all-in on aluminum construction pretty early on, so maybe they wouldn't be the natural choice for producing this plane.
  • Should be done in mid-late 30'ies, replacing the Ju 52 before ramping up to produce massive numbers of 52's.

(Though except for the steel/wood construction, this is not per se really a "Sten" aircraft...)
 
z42 said:
Didn't we have a thread recently were we discussed a better German transport? I think desirable qualities would be
...
(Though except for the steel/wood construction, this is not per se really a "Sten" aircraft...)
Click to expand...

'Sten' concept does not necessarily means 'better' - just like Sten SMG was not better than all of other SMGs
Concept is, or at least I'm reading it that way and wrt. aircraft, 'let's make a simple, cheap and producible A/C that can give useful service without much of delay'. Knocking an engine from Ju 52 nears it it to the concept; knocking two engines out of Ju 52 nears it further, since powerplant part of aircraft tended to be most expensive part.

z42 said:
2 engines. Germany was, perhaps, in general lacking a cheap and robust radial in the 1000-1200 hp range that could be mass-produced, like the R-1820 or R-1830. In lieu of that, Jumo 211 would do.
Click to expand...

There was the Bramo 323P, that was good for 1000 HP on 87 oct fuel; BMW 132s usually topped out at 900 HP, and were just with 1-speed S/C. The Ju 211 is a good choice, too, especially for the 1-engined transport.
Germans were using G&R 14N on some of their transports, 1180 HP max.


The Ju 52 certainly needs to be superseded with something more capable, I agree with SR6 that already the humble British transports were much better use of resources.
 

Ju 52 "1m" ('m' being the single BMW VII engine, of 685 PS) was able to take off in 180-255 meters, vs. the 3-engined 52s that needed 300 - 340m. Probably had to with the weight difference - 7 tons vs. 9-10.5, giving to the 3-engined types 30-50% greater wing loading. I'm not sure how much the appalling prop was to blame for the 3-engined types (toothpick, without ability to change the pass/angle in flight); not that 1-engined type had a great prop, but at least it was much more substantial.
The 1-engined type carried 2000 kg to 1000 km, 3-engied types carried 2000-2500 kg to 1060-850 km (1500 km with more fuel and 1740 kg of cargo); 3-engined types used 50% more fuel to do it.

(per 'Ju 52 Flugzeug & legende' book)

From the Luftwaffe point of view, a Ju 52 with less than 3 engines is a Sten both wrt. metal and wrt. fuel it needed.

Shortround6 said:
An-2 Colt carries roughly 2/3rds the passengers about 84% as far and is going 10mph slower (?) it may be a bit better than the JU-52 but it is tight.
Click to expand...

You mean worse than Ju 52, not better?


Turning the Ju 52 into a biplane was not my suggestion

Shortround6 said:
I have put forward the HP Harrow and Bristol Bombay before as examples. You don't need a DC-3 to beat the Ju-52.
Click to expand...

Agreed.
 
tomo pauk said:
You mean worse than Ju 52, not better?
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It might be better on a purchase cost per payload/mile basis, or even on an operating cost/ mile basis. But it going to be close and may even vary on the length of the trip?

Point is that just having a cheaper per aircraft cost may not be the best actual economy.
Just like the DC-3 was the first successful airliner. You could actually make money with it. Ticket prices and freight charges paid for the plane (loans), operating expenses (fuel, labor/maintenance, etc.) and had a bit of left over profit. Every airliner before that needed a government subsidy.

They made 80 of these things, needed government subsidy to make money for the Airlines. Boeing made money making them
 
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