Definition of Radius-Payload

[drrbradford]

Could someone please explain the above term in some detail. I have struggled to reach an exact answer for what it actually is.

To cite a specific example which I am trying to decrypt; the CH-53K will have a radius-payload of 27,000lb (12,246kg) over 110nm (203km).

Help appreciated.

Daniel.

[Two_Squirrels]

Daniel,

It is what it says on the tin. The CH-53K can carry a useful payload (i.e. passengers and/or cargo) of 27000lb for 110 nm and then return to base. Of course other factors will influence this, such as temperature and altitude. If the aircraft needed to carry more, then some fuel would need to be offloaded, and hence would not be able to fly as far (I am assuming that the example you quote is for full fuel.)

[NickLappos]

the example given is correctly stated by Two_squirrels, with a little more detail provided: The zero-NM payload is calculated by starting with the HOGE weight at the stated condition (the Marine Hot Day, 3000 feet, 31.5 degrees C) and then subtracting the equipped empty weight of the aircraft, all required mission equipment, the crew, the reserve fuel (usually 10% or 20 min, whichever is more). This is the max payload - the weight the aircraft can carry at HOGE with if it had only reserve fuel on board.
Then the fuel to fly out 110 miles (loaded) and back 110 miles (unloaded) is subtracted from the max payload, leaving 27,000 lbs.

To plot this on a Payload-Radius curve, place the max zero NM weight on the far left as the max value, along the upper left side. Then decrement the payload for each mile of fuel burned. Just take fuel flow and divide by TAS at best range speed - for the 53K, a guess might be about 28 lbs per mile range - 56 lb/mile radius (4000lbs/hr divided by 140 NM/hr = 28 Lb/NM). This means the 53K would pick up 34000 lb at zero miles, and 27,000 lbs at 110 miles.

[drrbradford]

The main err I had was about whether the helicopter returned unlaiden. The radius-payload curve for the 53K is given in the Sikorsky brochure, it doesn't seem to follow a linear pattern (if only life were that simple) so I assume the curve can only be obtained through flight testing?


Sorry for my lack of knowledge but what does H.O.G.E. stand for?

[sarbee]

'Hover Out of Ground Effect' - perhaps something to do with the payload being underslung, therefore having to hover out of ground effect in order to connect it and disconnect it on arrival?

FYI, H.I.G.E. is 'In' ground effect.
vbrgds.

[Matthew Parsons]

out of ground effect just to demonstrate worst case. If it was an external load then the radius-payload numbers would be different and would indicate that its an external load, and probably features of the load (density, drag, etc.)

[NickLappos]

Most military charts are predicated on HOGE, because they are helicopters, after all! The Standard US military design point is mission gross weight, Army hot day (4,000 feet and 95 deg F) or Marine Hot Day (3000 ft and 91.5 deg F) and either HOGE or 500 feet per minute vertical climb (about HOGE plus 10% extra power).

That is until the LUH competition, unfortunately....