Bloch Mb-140

[Archibald]

I've briefly mentionned this machine some months ago.

The Bloch MB-174 was one of the best machines of the AdA in May 1940. Its speed made it a very difficult target for the 109E (St Exupery, flight to Arras   ).
Sadly, it was only used for recon, because its bay only contained light and uneficient bombs. This was corrected with the MB-175, which came too late...

so, what was the MB-140 ? it was basically a four engined variant of the MB-175.
It seems that in this peculiar case, the four-engine variant would performed better than the two-engine layout, at least in speed and ceiling.

Building of the first prototype started in 1940, it was 60% complete (near Paris) when German invasion forced Bloch teams to destroy EVERYTHING, photos, blueprints, unfinished airframe...

I'm tempted to build one hacking Heller MB-174. How building a thing without any photos nor details on it ? with a bit of imagination...  
Bloch ingeniers worked on a great numbers of prototypes in the 1938-1940 era.
In fact there was three lineage of Bloch bombers

- improved MB-131s (twin and four engines layouts, final result was the MB-134 which looked like a 20% scaled-up MB-174)

- improved MB-174 (MB-175, MB-140)

- MB-161 "Languedoc" bombers derivatives (MB-162).

Well, all these prototypes (I know, this is a mess!) were brainchilds of the same team of ingeniers and, as a consequence they all look similar. I suppose that the MB-140 would have been very, very similar to the 174 / 175    

French philosophy for bombers in 1940 was something between Mosquito and
B-17.
I mean, four engine bombers with a light defensive armement (no turrets, few machine guns). Defensive armement was sacrificed in favor of aerodynamics and a speed about  340 mph or so in most cases (CAO-700, Br.482,
MB-162 "Languedoc bomber" and MB-140 are the best examples of this philosophy).

[Archibald]

Ok, here's some pics to clarify the thing. I've atempted to create a Bloch MB-140 strating from the MB-174/ 175 family. I've used the wings of a MB-135 to have a decent four-engine layout.

First, here's the MB-175, bomber variant of the MB-174.


And here's two  Bloch 140 atempts. Problem is, rear fuselage must be longer, hence a CofG problem (nose too short). Two solutions

- wings more on the rear (look better, but less real world)


- longer nose (more realistic, but look not very good)

[McGreig]

I prefer the version with the longer nose, although I don't suppose that it would exactly improve the pilot's vision for take off and landing.

Also, I'm not an engineer, but didn't the Ju-88G-10 have a significant increase in rear fuselage length without any increase ahead of the wing?

[elmayerle]

I'm not sure you need the longer nose for weight and balance purposes. The two extra engines forward of the cg will help and I'm not at all certain that you need so large a horizontal tail   If you do need to move weight forward to balance the aircraft, how about moving some large masses by extending the engine nacelles and moving the engines forward?

Just my $0.02.

[Archibald]

I prefer the version with the longer nose, although I don't suppose that it would exactly improve the pilot's vision for take off and landing.

Also, I'm not an engineer, but didn't the Ju-88G-10 have a significant increase in rear fuselage length without any increase ahead of the wing?

The variant you like is the more realistic. I mean, moving the wings would have been very difficult.  Having a longer nose would be easier... just stretch a bit the forward fuselage.

In fact I'll drawn a third variant  with the MB-175 "short" nose. Thank you for the tip on the Ju-88...    

I've improved a bit my pics. So here's the whole serie...

Bloch MB-175


Bloch MB-140 basic variant. I mean, a MB-175 with four engines, a longer rear fuselage, and no modification to the forward fuselage. That's clearly my favorite, and what I'll try to build soon, if I managed to find Heller MB-174 kit
Nose could be too short, eventually leading to CofG problems (not sure of that)



If problems arise because of the longer rear fuselage, there's two solutions to keep a good CofG
- move the wing backward
- stretch the nose of your aircraft as you stretched its rear fuselage.

In the french designation system of 1940, such mods would lead to a different variant, hence the MB-141 designation    

MB-141 with stretched nose


MB-141 with wing moved backward (using the cockpit frames and Heller
Bloch MB-174,  I've found 1.5 cm at 1/72 scale, meaning 1 meter at 1/1 scale. Moving a wing 1 m backward...    not an easy task!


Et voila! A whole family of MB-175 derivatives  

[Archibald]

Building of this MB-140 has started... weeks ago (and they thought I had stopped modelling after the IRIAF Arrow ??!!! )
It progress nicely, pictures will come soon...  

[ysi_maniac]

This promises to be a winner