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Improved Jarahi MTB
Jarahi II
70x19x5 ft
35 tons
2x2 25mm AA, 4x18"TT, 6 D.C.
3x 1300 hp GWM V-1300 liquid cooled engines
45 knots
1000 nm cruising radius
Improved version of the experimental Jarahi
Jarahi
70x19x5 ft
35 tons
2x20mm, 4x0.50 cal mg, 4x18"TT, 6 D.C.
3x 1200 hp Roth-Packard liquid cooled engines
41 knots
1200 nm cruising radius
Using the same hull form and increased weight of both main armament and larger engines you'd still likely have a top speed of 41 knots.
Most imroved Atlantean MTB's have a top speed of 44 knots, the Jarahi being based on the MTB-1 type, would be an older design.
I am not sure the armament is heavier (in kg) and I assume that the engines are roughly the same weight while range is 200NM less
Improved Mand
55x11x3 ft
15 tons
1x25mm forward, 2x18"TT, 4 D.C.
1 x 1300 Hp GWM V-1300
100 nm @ 35 knots
45 knots
I assume the Jarahi II's also now mount their 2x18" torpedo tubes on the side rather than having the bow and stern tubes.
How many have been/will be built?
None built, posted to see if there are any objections to the specs.
EDIT: I assumed that the Jarahi was an experimental boat since the Encyclopedia didnt mention Atlantis
This post has been edited 1 times, last edit by "Vukovlad" (Apr 23rd 2008, 5:45pm)
Atlantis sold one MTB-1 type and one CMB type to Persia in 1932 IIRC.
I didn't really follow what Persia had build after that in the way of MTB's because, well, there was no one playing Persia for a while.
Don't forget that the ammo for the 25mm will also weigh more, though the Jarahi II's lack the 50 cals of the Jahari I.
Its too bad Springsharp designs small ships poorly because its really hard to tell just what kind of weights we're talking about unless you look up figures from various sources.
For all we know the larger engines may not fit or may even strain the wooden hull somewhat. You might even find out that later on in their career they develope cracks along their upper hull from being driven at high speeds into short head sea's.
Other than possible cracks do you think that the following specs are acceptable?
Jarahi II
70x19x5 ft
35 tons
2x2 25mm AA, 4x18"TT, 6 D.C.
3x 1300 hp GWM V-1300 liquid cooled engines
43 knots
1000 nm cruising radius
Mand II
55x11x3 ft
15 tons
1x25mm forward, 2x18"TT, 4 D.C.
1 x 1300 Hp GWM V-1300
100 nm @ 35 knots
45 knots
Seems like a marginal improvement on the designs, which seems realistic. I'm more concerned about the Mand II design, going from 2x500 hp engines to one large 1,300 hp engine. The engine should fit but the weight may be an issue.
That said without weight specs for the engines I really can't fault them too much. As RA's said in the Russian quarterly post, the smaller designs speed will be significantly reduced in rough sea's. Increasing the speed by 10 knots is a significant boost in speed.
As noted in the GW thread the dry weight is 690 Kg
The 500 Hp Roth petrol engines would be roughly 400 Kg each, total 800 KG, so engine weight shouldn't be an issue in the Mand II.
Roth-Pakards on the other hand are roughly 330 Kg.
1200 hp Roth-Packard, 330 Kg seems very low
Originally posted by Vukovlad
1200 hp Roth-Packard, 330 Kg seems very low
Agreed, that would be VERY low.
Although the engines used in this application will be commonly derived from aircraft engines, they aren't actually aircraft engines. They are considerably stronger and heavier. The Isotta-Fraschini Asso in the Italian boats was capable of running for hundreds of hours at high throttle settings. Aircraft engines might be good for a couple of hours at most. The Isotta-Fraschini Asso gave 1000hp, later 1150hp and weighed in at 1350kg.
In that case 200 kg extra shouldnt be that a big deal
Sunday, September 8th 2024, 5:36am
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