There’s a photograph of this helicopter on the cover page of this site at the moment
What I don’t understand is why the external fuel tanks are mounted so high up
What’s the point ? I don’t see any reason why they couldn’t be attached much lower and all that weight up high can’t help with stability
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- ReverseFlow
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Re: S-70 JASDF question
You mean this photo I guess.
https://www.airliners.net/photo/Japan-A ... 12/7166141
I would say it's so that it is not in the way of th doors and getting in and out?
https://www.airliners.net/photo/Japan-A ... 12/7166141
I would say it's so that it is not in the way of th doors and getting in and out?
Re: S-70 JASDF question
Probably to reduce the moment arm, with respect to the aircraft center of gravity, of the aerodynamic forces acting on the tanks in forward flight, and of the weight of the fuel with full tanks.
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- LyleLanley
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Re: S-70 JASDF question
My guess is it's for visibility for the observer in the bubbles and the pilots. This Black Hawk is a SAR asset so external fuel and a probe are great, but with the lower tanks like what you'd see on the 160th SOAR birds, the visibility to the sides and rear would suck. Not a big deal if you've got shooters like the SOAR, but a SAR bird needs to have great visibility if you're looking for a disabled boat or someone floating on the water like a downed aviator.
Pretty ingenious and calls to mind the F4U Corsair.
Pretty ingenious and calls to mind the F4U Corsair.
Re: S-70 JASDF question
LyleLanley wrote:My guess is it's for visibility for the observer in the bubbles and the pilots. This Black Hawk is a SAR asset so external fuel and a probe are great, but with the lower tanks like what you'd see on the 160th SOAR birds, the visibility to the sides and rear would suck. Not a big deal if you've got shooters like the SOAR, but a SAR bird needs to have great visibility if you're looking for a disabled boat or someone floating on the water like a downed aviator.
Pretty ingenious and calls to mind the F4U Corsair.
That makes a lot of sense, it can’t help the stability to have that much weight added so high up but I can see how it would be worth the trade off for the reasons you mentioned
Re: S-70 JASDF question
Max Q wrote:That makes a lot of sense, it can’t help the stability to have that much weight added so high up but I can see how it would be worth the trade off for the reasons you mentioned
Actually, it does, unless you are floating, in which case weight up does decrease stability, which is lousy anyway because of the weight of rotor and engines. The tanks are draggy, so if they were low the drag would generate a nose-down pitching moment in forward flight that would have to be counteracted somehow, probably by more download on the horizontal tail. If you are going to have extra weight, you'd want to have it as close as possible to the center of gravity, which generally is up high (because of rotor, transmission, and engines).
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- LyleLanley
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Re: S-70 JASDF question
Max Q wrote:That makes a lot of sense, it can’t help the stability to have that much weight added so high up but I can see how it would be worth the trade off for the reasons you mentioned
I can barely spell helicopter so I'm probably far off, but wouldn't it make the helicopter more stable to have the weight closer to the plane of it's lift vector, i.e. higher up and closer to the rotor? Trying to think of the figure skater pulling in closer to the plane rotation.
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