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Old 07-20-2010, 11:47 AM   #21
Phaelen Bleux
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Default Re: [WWII] Manta Squadron Airplane

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Originally Posted by Michele View Post
Gosh - and the propeller blades survive the dive! From the description, it also seems the pods are "turrets" or something like vectored thrust should be used, because the air propellers turn around and serve as water screws... A tad too over-the-top for my liking, I'm afraid - but Weird World War Two has room for anything, of course, and if a playing group likes weird tech...
Yep, the whole design is an over-the-top handwave, alright. The challenge was to see if it could work. . .but the ultimate answer is, "no, not really."

Quote:
Without putting in the DVD, this seems rather large for what I remember. A 483mm or 500mm torpedo (from Motor Pool) seems more appropriate.
A. I was trying to stick with a British torp. B. My bad for assuming smallest mm = lightest torp. I was trying to pick the smallest one available.

Quote:
I'm not really even sure where the engines are really supposed to be, as I couldn't see any obvious air intakes. Maybe the props use electric motors powered by batteries located behind the pilot ...
That may have been a smarter design choice, since the pods appear very small--not large enough for a significant powerplant in any event. Then the plane could use the same power system above and below water.

Quote:
The Manta would probably upgrade to the Heavy Fighter chassis.
I downgraded to Medium frame on account of the "self-inflicted HP" collision problem. Less HP = less need for armor.

And thanks for finding the great picture. . .I never found anything! I finally popped in the DVD, paused it, a took a digital photo of the screen to base the design on!
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Old 07-20-2010, 04:22 PM   #22
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Default Re: [WWII] Manta Squadron Airplane

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Originally Posted by Phaelen Bleux View Post
A. I was trying to stick with a British torp. B. My bad for assuming smallest mm = lightest torp. I was trying to pick the smallest one available.
After popping in the DVD, it's clear that they are too small for the WWII aircraft torpedoes, more along the size of a 120-130mm rocket.

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That may have been a smarter design choice, since the pods appear very small--not large enough for a significant powerplant in any event. Then the plane could use the same power system above and below water.
There was a distinctive piston engine sound in the movie when one of the Mantas started up, but I'd go electric anyway. The biggest problem is the limited duration of TL6 batteries (and the weight of electric motors from MVDS, if you use that option).

I know I had all kinds of problems with WWII electric battelsuits.
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Old 07-20-2010, 09:10 PM   #23
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Default Re: [WWII] Manta Squadron Airplane

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There was a distinctive piston engine sound in the movie when one of the Mantas started up, but I'd go electric anyway. The biggest problem is the limited duration of TL6 batteries (and the weight of electric motors from MVDS, if you use that option).
I guess for me it is a toss-up between sticking with the spirit of the design as seen in the movie vs. shoe-horning it into something that would work in the Vehicle design system.

The other inaccuracy with the missiles/torps this that in the movie the spread after launch makes the missiles look like they are coming off wing hardpoints--which are never in evidence at any other time.
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Old 07-21-2010, 12:54 AM   #24
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Default Re: [WWII] Manta Squadron Airplane

I think a lot of the technology in Sky Captain implies the existence of much higher energy storage densities than was possible in that era. In fact, they have much higher energy storage densities then we have now (handheld directed energy weapons are possible, for example). Why not use TL9 or 10 Energy Cells instead?
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Old 07-21-2010, 10:22 AM   #25
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Default Re: [WWII] Manta Squadron Airplane

I'v toyed with GURPS Vehicles for 3e, since the MVDS is compatible with that but it doesn't provide the same freedom as to chassis weight and tech options etc.

I managed a back-of-the-envelope concept for a vehicle that can fly and move as a sub. It doesn't look like the Manta because:
a) I gave it a jet engine instead of propellers. Looks like marginally safer to dive in.
b) I gave it just one torpedo, a 450mm, in an internal bay.
c) I gave it pop-out wings, again for the plunge, and another reason to use Vehicles instead of the MVDS.
d) Even so, it flies like a cargo plane, not a fighter, and it swims like a drunken pig.

I used all weight-saving options, so that it came ungodly expensive. Even so, it is also plagued by 1-hour endurance underwater and 2 hours in the air. It simply weighs too much. Oh, and the stall speed is over 150 mph. I assumed it takes off from the water like a seaplane, but I did not check whether it can make that speed on the water.

All of that, by using TL6 tech (well, the pop-out wings are remarkable but I think they could be accepted) and not exceedingly unbelievable assumptions (I even gave it 20 DR, which is more than an aircraft but less than a sub). I suppose one could do better with TL6+1 or more...
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Old 07-21-2010, 12:32 PM   #26
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Default Re: [WWII] Manta Squadron Airplane

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Originally Posted by Michele View Post
I'v toyed with GURPS Vehicles for 3e, since the MVDS is compatible with that but it doesn't provide the same freedom as to chassis weight and tech options etc.

I managed a back-of-the-envelope concept for a vehicle that can fly and move as a sub. It doesn't look like the Manta because:
a) I gave it a jet engine instead of propellers. Looks like marginally safer to dive in.
b) I gave it just one torpedo, a 450mm, in an internal bay.
c) I gave it pop-out wings, again for the plunge, and another reason to use Vehicles instead of the MVDS.
d) Even so, it flies like a cargo plane, not a fighter, and it swims like a drunken pig.

I used all weight-saving options, so that it came ungodly expensive. Even so, it is also plagued by 1-hour endurance underwater and 2 hours in the air. It simply weighs too much. Oh, and the stall speed is over 150 mph. I assumed it takes off from the water like a seaplane, but I did not check whether it can make that speed on the water.

All of that, by using TL6 tech (well, the pop-out wings are remarkable but I think they could be accepted) and not exceedingly unbelievable assumptions (I even gave it 20 DR, which is more than an aircraft but less than a sub). I suppose one could do better with TL6+1 or more...
Well, I think all that actually makes me feel pretty good about the Manta's design. . .we have similar endurances (3 hrs air, 1 water), similar stall (148) and a very heavy craft.

With aAccel 2 and aMR 3, the Manta has about as much chance in a dogfight as a lead balloon.

Since you were going for total reality, how do you think the pilot of your craft will fare on impact??

BTW:
1. I used Vehicles not MVDS for the Manta as well. . .I decided right away the MVDS would be to clunky for a design this complicated.
2. Your plane might look like this:

http://www.waterufo.net/flyingsubs/N...ngSubHtml1.htm

Obviously, this is an old, crazy idea!

I'd love it if you posted your design!
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Old 07-22-2010, 01:58 AM   #27
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Default Re: [WWII] Manta Squadron Airplane

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Originally Posted by Phaelen Bleux View Post
Well, I think all that actually makes me feel pretty good about the Manta's design. . .we have similar endurances (3 hrs air, 1 water), similar stall (148) and a very heavy craft.

With aAccel 2 and aMR 3, the Manta has about as much chance in a dogfight as a lead balloon.

Since you were going for total reality, how do you think the pilot of your craft will fare on impact??
No idea, I didn't go that far.

Quote:

I'd love it if you posted your design!
Sorry but I won't, it's not finished. I stopped when it became clear I could have something that flew and might survive uncer water for a short while, but that performed like a Ju 52 with high stall speed and could possibly not even be able to take off. Apart from the issue of the dive, it was nothing like the vehicle depicted.

The exercise could, however, bring me to come up with entirely new fictional designs linking air and ASW. We'll see...
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Old 07-22-2010, 03:16 AM   #28
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Default Re: [WWII] Manta Squadron Airplane

Here's a vaguely more realistic concept:

http://www.military.com/forums/0,15240,179699,00.html
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Old 07-22-2010, 03:31 PM   #29
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Default Re: [WWII] Manta Squadron Airplane

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Here's a vaguely more realistic concept:

http://www.military.com/forums/0,15240,179699,00.html
Alright, I'll take the bait. I printed off the USN's design goals, and I'm going to see what's possible.
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Old 07-28-2010, 04:02 PM   #30
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Default Re: [WWII] Manta Squadron Airplane

Now that I can get it into the water, I can't get it back out again!!!!

Should having the plane up on skis help with the hDrag more? Suggestions?

Convair XY-1OSTB-A "Loon" Submersible Flying Boat (early TL7)
In the 1960s, the USN began looking at the idea of a submersible aircraft that could land in remote waters, submerge, and begin spying on or attacking enemy positions. The Navy created a "wish list" for such a craft, and awarded a contract to Convair to develop a prototype. Convair engineers envisioned a jet powered by three engines, two turbojets and one turbofan. The turbojets would be used for takeoff, and the turbofan for routine cruise flight. It would land on retractable hydro-skis, and then most of the plane would be flooded (excluding only the cockpit). The fuel tanks would be fitted with rubber diaphragms, allowing water to displace the empty volume of the fuel tanks without mixing with the jet fuel. Butterfly valves on the engine nacelles would protect the engines; other than a cloud of soot as the engines were relit, there would be no impact on the operation of the jets.
The Loon has a crew of two. Instead of 1,500 lbs. of ordnance, the jet could instead carry eight agents for covert insertion operations. It burns 60 gallons of jet fuel per hour at routine usage. A full load of MG ammo is $7 and a fuel tank of fuel costs $405.

Subassemblies: Body +5, STOL Wings +2, two engine Pods +1; 2 retractable skids +1.
Powertrain: Two 4,000-kW turbojets and one 2,000-kW light turbofan, plus two 15-kW hydrojets with two 216,000-kWs lead-acid batteries.
Fuel: 135 gallons jet fuel in collapsible fuel tanks (Fire 15) [Wings].
Occupancy: 2 NCS +/- 8 CPS.
Cargo: None.

Armor
Overall: 3/5.

Weaponry:
7.62mm LMG [Body:F] (250 rounds each).
1,500 lbs. ordnance [Body:U].

Equipment:
Body: Long range radio with scrambler (300-mile), active sonar (Scan 11, 1 mile), 15-mile radar (Scan 18), vehicle camera, autopilot, precision navigation instruments, IFF, 1-mile searchlight (for use underwater), advanced bombsight, 1,500-lb. weapon bay, 2-man escape capsule, 4 man-days limited life support, 8 folding seats.

Statistics:
Size: ? Payload: 2,801 lbs. Lwt.: 15.34 tons
Volume: 900 cf. Maint.: 12 hours Price: $2,655,821

HT: 8. HPs: 501 Body, 223 each Wing, 55 each Pod, 69 each Skid.

aSpeed: 275 aAccel: 1 aDecel: 14 aMR: 3.5 aSR: 4
Stall Speed: 94.
wSpeed: 32 wAccel: 6.5 wDecel: 1 (4) wMR: 0.1 aSR: 3
Draft: 2.7'. Flotation Rating: 34,080 lbs.
uSpeed: 7 uAccel: 0.25 uDecel: 0.7 (1) uMR: 0.25 aSR: 3
uDraft: 10.4'.
gSpeed: 153.

Design Notes:
Body is 710 cf; wings are 55 cf each, pods are 15 cf each, skids are 35.5 cf. Structure is Medium, Standard with Very Good Streamlining, Fine Hydrodynamic Lines and Submersible (Sealed). Mechanical Controls. Armor is Expensive Metal.
The weapons bay houses some of the passenger seats; when passengers are carried, no ordnance is carried.
Design wSpeed is far too low to allow takeoff. A headwind of 62 mph (or 25 mph, if one uses the rule on p. W149) is required for takeoff.
The aircraft can easily takeoff from land, however.
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