Breda BA65 as a Torpedo bomber!

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Vincent Biondi
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Breda BA65 as a Torpedo bomber!

Post by Vincent Biondi » Sat Mar 20, 2010 11:27 am

Hello All,
Last night I saw a movie that I haven't seen in years. TORA TORA TORA.
During the movie, as the Japanese Commanders were planning the attack on Pearl Harbour, they practiced the torpedo assaults in a bay, north part of Japan, that was similar to Pearl Harbour.
When I watched the Nakajima Kates practice their runs, I noticed that this aircraft was very close in size and looks to the Breda 65.
After doing some research on both aircraft, I was surprised to find that both were almost identical in size, speed, defensive armament and weight.
The only difference was the range of the Kate was more than that of the Ba65.
Here is my question, since the results of the Ba65 were less than expected as an attack bomber, why wasen't this aircraft used as a torpedo bomber, since it possessed many qualities of the Kate?
Also, the cost of producing a BA65, compared to an SM79, were less, not to mention that fact that it had a crew of two instead of six for the SM79.
Any thoughts?
Vincent.

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Aeroal
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Ba65 Sil?

Post by Aeroal » Sat Mar 20, 2010 12:56 pm

Vince,

The problem with the Breda was that its engine was seriously underpowered for the airframe, leaving little useful payload.

Someone can correct me if I am wrong, but I seem to have read that the turret fighter was so heavy for the engine, that its performance was barely marginal, to say the least. I can only presume that any thoughts of lifting a torpedo were out of the question.

Regards,

Aeroal.

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Post by Vincent Biondi » Sat Mar 20, 2010 2:13 pm

Hi Aeroal,
Actually, the engine of the Ba65 and Kate were the same horsepower:
BA65: Powerplant: 1× Fiat A.80 RC.41 radial engine, 746 kW (1,000 hp)
Kate: Powerplant: 1× Nakajima Sakae 11 radial engine, 750 kW (1,000 hp)
As I mentioned before, I found the similarities of both aircraft quite surprising.
So, given the fact that both had the same size radial engine, horsepower and roughly the same bomb (weight) capacity, why was it not used as a torpedo bomber?
Torpedo Stats:
Japanese Torpedo: 850 kg (1,860 lb) type 91 torpedo
Italian Torpedo: 900 Kg (1980 lb) Whitehead Fiume torpedo
As far as the turret fighter being heavy for the engine, I am not sure about that, but I would think that the BA65 had enough power to carry a torpedo.
Don't forget that the Kate, like any other torpedo bomber was slow and flew low. Again, similarities with the BA65.

Vincent.

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Aeroal
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Ba65 Sil?

Post by Aeroal » Mon Mar 22, 2010 8:56 am

Vince,
I have just had a quick glance at Ali d'Italia No. 7 and it confirms my original thoughts.

The K14 engined machine was so heavy that the rear cockpits were faired over and the machines were flown as single seaters to save weight. One was flown at its designed loadings inclusive of fuel, oil, crew and warload of 1165 kilos, but was unable to maintain flight. When the load was decreased to 900 kilos it could fly, but with unpleasant handling characteristics.

The A80 powered version suffered from a tailing off of performance, in the Western desert, due to heat and dust ingestion. So the Ba65 was clearly not an easy aircraft to fly.

This still does not answer why two aircraft of roughly the same size and power were so radically different in their performance. I can only presume it was down to wing loading and aerodynamics. If anyone can give a definitive answer, I would be very interested to hear it.

Regards,

Aeroal.

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Vincent Biondi
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Post by Vincent Biondi » Mon Mar 22, 2010 10:18 am

Hi Aeroal,
You raise some interesting points.
I wonder though, if it ever was considered for the torpedo role by the high command.
Thanks for the info.
Vincent.

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Post by Alex T. » Thu Apr 22, 2010 2:34 pm

Hi guys, I believe that the answer should be looked into the design of the machines: the Kate was longer, sleeker and above all had a larger wingspan and wing surface.

From Wikipedia (I know, I know...)

B5N
Crew: 3 (1 pilot, 1 commander and 1 backgunner/radio operator)
Length: 10.30 m (33 ft 9½ in)
Wingspan: 15.52 m (50 ft 11 in)
Height: 3.70 m (12 ft 1⅝ in)
Wing area: 37.7 m² (406 ft²)
Empty weight: 2,279 kg (5,024 lb)
Loaded weight: 3,800 kg (8,380 lb)
Max takeoff weight: 4,100 kg (9,040 lb)

Powerplant: 1× Nakajima Sakae 11 radial engine, 750 kW (1,000 hp)


Breda Ba.65
Crew: 1
Length: 9.30 m (30 ft 6.1 in)
Wingspan: 12.10 m (39 ft 8.4 in)

Height: 3.20 m (10 ft 6 in)
Wing area: 23.5 m² (253 ft²)
Empty weight: 2,400 kg (5,300 lb)
Max takeoff weight: 2,950 kg (6,500 lb)

Powerplant: 1× Fiat A.80 RC.41 radial engine, 746 kW (1,000 hp)

The result was a 400kg difference in payload, which is a lot. Breda has never been renowned for its aeronautical creations :wink:

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Breda Ba65.

Post by Aeroal » Fri Apr 23, 2010 2:44 am

Alex,

I think you have nailed it. The Breda's somewhat smaller wingspan would result in a much higher wingload, and thus induce marginal handling at all speeds and especially at critical times such as take-off and landing. This instability and lack of performance would increase dramatically when carrying a maximum warload.

This begs the question : If the design was inadequate, why did Breda not increase the wingspan by fitting wing extensions, to increase the stability and practicality of the machine?

Regards,

Aeroal.

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Post by Alex T. » Fri Apr 23, 2010 5:50 am

Hi Aeroal,

the wings of Italian planes are renowned for their sturdiness, and the Breda one is no different! If you have the Ali d' Italia book about the Breda, have a look at the structural view of the wing: it's a double spar tubular structure with aluminium ribs and skin, a really robust but heavy construction, and difficult to extend without a major redesign and worse, without adding weight.
The Breda engineers already tried to save weight on the back of the fuselage, covering it in canvas, but that didn't seem to be enough, as the plane was built "like a tank" if you know what I mean.
The 3,20 metres difference in wingspan with the B5N would have easily added at least an extra 200kg, which then would have just caused a heavier machine.
More than a wing extension, the plane needed some major surgery on the fuselage to lose some weight, but the real problem was the unnecessarily big and heavy fuselage section, built with a construction technique that might have been marginally efficient with the Br.20 or S.79 (probably because of the wooden wings), but not on a small size plane like this.
So basically the only way to fix the plane was to redesign it.. or get rid of it and flog it to small countries at very low prices. It'd be interesting to see what deals were made with the various buyers.

A.

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