"Stretch or not strech" of aircraft designs

[gumbyk]

If we are gonna be pedantic about it, the engines are actually Dongan HS-7s built in China, which are licence copies of the ASh-82 - all the Flug Werk '190s are powered by this engine, as far as I know, so the piccie you should be posting of the aircraft powered by one is this!

The Flugwerk FW-190 in NZ has an Ash82-T engine fitted. I can't find my photos of the data plate, but all my other records state the Ash-82T, and the manuals supplied with it were Russian.

 

[Greg Boeser]

A lot of the "mission creep" started fairly early. In part because the B-25 and the B-26 were in the design stage before WW II started in Poland.
"on August 10, 1939, the Army issued a contract for 201 Model 179s under the designation B-26 "
The plane was ordered off the drawing board with no prototype.
Combat experience by the French and British showed that the original set up as designed had several flaws or gaps in capability. (no armor or self sealing tanks for one thing)

"Although the first B-26 had yet to fly, orders for 139 B-26As with self-sealing tanks and armor were issued on September 16. Further orders for 719 B-26Bs on September 28, 1940 brought the total B-26 order to 1131 aircraft."

first Flight by a B-26 was not until November 25, 1940 and the Army got the first ones on February 22, 1941.
One the early aircraft there was single .30 cal in the tip of the nose, the two .50s in the top turret (first power turret on a US bomber) a single .30 cal out the bottom and a single .50 in the tail. Crew was five men.
Crew weight, as given in the weight and loading charts in the March 1942 manual, was rather optimistic. 950lbs for all five men including parachutes, WHile the pilot, copilot and radio operator could all weigh 200lbs each (with parachute) the navigator was a svelte 180lbs and the gunner a mere 170lbs (again with parachute).
Ammo for the guns was 600 rounds for each of the .30 cal guns and 200 rounds for each of the .50s.
At the rear of the plane the turret gunner was expected to get out of the turret and lay on his belly to operate the .30 cal tunnel gun and then bounce up and climb into the turret if the threat should get into the upper hemisphere of the plane.

Radio operator (or co-pilot?) went through the bomb bay and into the the tail to man the tail gun (?) hardly an ideal situation in combat.

The 326mph listed in the manual for the early planes was done at 26,734 lbs design weight. But normal gross weight as operated was 28,706 lbs which included only four 500lb bombs and just 465 gallons of fuel.

for those who are interested the manual for the early planes is here: http://www.wwiiaircraftperformance.org/B-26/B-26_Operation_and_Flight_Instructions.pdf
with lots of charts and tables.

The high performance of the early B-26 was somewhat of an illusion as even without chin guns and some of the other add ons it's combat weight had gone up thousands of pounds.
The size of the bomb bay was not governed by the requirement to carry a torpedo but by the desire of the AAF to carry thirty 100lb bombs.

Some speed was lost by the deletion of the propeller spinners and the larger air intakes (to house dust/dirt filters) and perhaps a large oil cooler intake.

there are 3 basic B-26s, the original small wing, the big wing and the big wing with tilt.

I think that combat weight was based on the idea that the aircraft would perform at that weight at the target. Take off weight included the full 962 gallons of fuel, or a bit less. Max takeoff weight was restricted to 36,500 lbs. in the short wing versions. The long wing versions had no such restriction, so I assume that meant that you could cram them full and still have a margin of safety. They did of course reduce the maximum # of bombs the plane could carry by eliminating the rear bomb bay.

 

[nuuumannn]

The Flugwerk FW-190 in NZ has an Ash82-T engine fitted.

Oh, just discovered your response, Aaron. Yes, I know and there are one or two others built with the ASh-82 as well, apparently. Was the Russian engine originally fitted though?

 

[gumbyk]

Oh, just discovered your response, Aaron. Yes, I know and there are one or two others built with the ASh-82 as well, apparently. Was the Russian engine originally fitted though?

From memory, the aircraft only had test flying hours on it when it came into the country, and it was all done on the Ash-82, so it was fitted from new.

 

[nuuumannn]

Ah, interesting. I had read that the intent was to fit the Chinese engines, perhaps after the Chariots aircraft, since it was the next production one? Cost perhaps?

 

[gumbyk]

Ah, interesting. I had read that the intent was to fit the Chinese engines, perhaps after the Chariots aircraft, since it was the next production one? Cost perhaps?

Not sure. For some reason I didn't take copies of all documents like I normally do.
If the situation was anything like the Housai 6 engines, then the Russian engines were probably significantly cheaper. A new M-14 is a lot cheaper than the Housai, althoug hI think that is about to change with the Chinese starting production of the CJ-6 for the civilian market.

 

[pinehilljoe]

The B-24 was stretched into the PB4Y. Seven feet added to the fuselage, an additional Bendix top turret, and the redesigned tail that would probably have been used on all B-24s if production had continued.

 

[Admiral Beez]

I would have liked the Spitfire stretched like the FW190 for no other reason than to give it more internal fuel capacity.

AIUI, the core fuselage of the Merlin—powered Spitifre had very few changes throughout its production. A good use of jigs and tooling if true.

 

[Zipper730]

Before viagra...

View attachment 555879

After...

View attachment 555878

 

[P-39 Expert]

Before viagra...

View attachment 555879

After...

View attachment 555878

Hilarious.

 

[Admiral Beez]

I think the question is whether the airframe can be modified/upgraded to suit the later war high H/P engines successfully, the Spitfire P51 FW190 P47 are examples that did.

I've read somewhere that the main fuselage of the Spitfire (from the firewall to the tail attachment) remained unchanged from the first to the last unit.

I'm trying to find that reference, I assume the bubble canopy ones were different for a start. Perhaps this only applied to the Merlin-powered Spits.

 

[Shortround6]

This is one of those cases where you have to read very carefully, and some writers may have interpreted the original and not very well.

Similar method of construction is not the same as remained unchanged from the first to the last unit

Now in the picture above note the top and bottom longerons and the datum longerons on each side.

There are a number of references to these longerons being strengthened as more powerful engines were fitted.

I have no idea if the skin thickness was ever changed in any areas. That would be a change but not a change in the method of construction or even a change in the number of parts or operations needed to assemble the fuselage.