Hydraulic Palm tree (BTW, Nice name!!),
Your questions indicate that when I apply at Westlands for that marketing assignment, you can be my right hand man for preparing marketing literature. If I can explain it to you, it is ready for prime time! Not that the info is self explanitory, but you mixed up max gross weight with mission takeoff weight, and then applied some common sense from other helicopters. This leads you to believe that I have pulled some slight of hand. Not so! I believe the data is there for you to see, let me try to explain.
The S-92 has a max gross weight of 26,150 lbs, the H-92 28,300 lbs. The empty weight of either varies based on mission equipment, of course. Equipped with all the military equipment of the UH-60L Black Hawk, including IR supressor, the H-92 weighs 15,800 lbs. That includes a dual autopilot, blade deice and lots of nav and comm. So, with 2 crew at 250 each, the H-92 has a zero fuel weight of about 16,300 pounds, and a payload of 28,300 minus 16,300 or 12,000 pounds. With a good load of SAR equipment, it would have an empty weight of about 17,000 lbs (1200 pounds of extra stuff above a military utility aircraft). This includes dual hoist, dual coupled auto approach, GPS nav, SAT comm and a bunch of equipment in the lockers in the cabin, enough to start several Boy Scout Camps. The H-92 SAR chart assumes that 17,000 empty weight. It says 23,000 lbs takeoff weight with main fuel (5,000 lbs). The SAR crew is assumed to be 4 people at 250 lbs apiece, so we have the 17,000 empty weight, 1,000 of crew, and 5,000 of fuel. So far, I get the beer, n'est-pas?
If we travel out at Vbr, the aircraft burns about 1300 to 1350 pounds per hour, mission average. 137 knots divided into 1300 pounds per hour is 9.5 pounds of fuel per nautical mile traveled. [That is the best way to figure out range, not hours and stuff, because you do not travel hours, you travel miles, right?]
BTW, if we had three engines or two main rotors, we would burn about 30% more gas, which leads me to realize why you are aghast at this miserly fuel consumption! Welcome to the 21st century, where gas milage counts.
Back to the mission, we burn about 10 pounds per NM, so the rest is easy, for 250 raduis, we need 5000 pounds of mission fuel, for 350 radius, we need 7,000 pounds. It is no coincidence that the main plus aux fuel is 7,300 pounds, which at the actual 9.5 lb/NM yields 350 NM radius with reserve.
Now, to answer your comments in detail:
Normal range is about 250 NM radius only when you carry little payload, you say "flippin tight" and so does the chart, which shows barely 245Nm only when no payload is carried. Pity you were "flippin tight" when you looked at the chart, otherwise you would have seen that it agreed with you. Try it next time in the morning, when things are clearer.
If you had actually read the last post where I discussed the chart, you would have seen that the 250 radius is best done with the aux fuel, where there is plenty of gas for the 250 trip, plus the time to hoist up those "flippin tight" party revelers who needed to to be winched into the H-92. When you travel out the 250 NM, having taken off with full main and aux fuel, you have burned down about 2400 pounds of gas (remember the 9.5 pounds per NM? 250 x 9.5= 2375 pounds down). That means that you enter the hover at 23,586 pounds (giving you 4,700 pounds of available payload to get to the 28,300 MGW). If you take 2.5 minutes per rescuee, 20 of them takes you 50 minutes. At 1550 pounds per hour in the hover, 50 minutes consumes about 1300 pounds of fuel, leaving you with 3656 pounds of fuel left (7331 takeoff, 2375 fuel outbound, 1300 fuel to hover = 3656 left for home and reserve). If you burn 9.5 pounds per mile, the 3656 will take you 384 miles to burnout. Leave off 70 Nm for reserve (half hour at Vbr) and you can return 314 NM and have lots of reserve.
Now, helicopter aerial refueling is great, Sikorsky invented it, and has built about 3,000 helicopters using it. The H-92 will have it in a bit, fear not.
Regarding max range, the figures are easy to arrive at. Recall the H-92 with Black Hawk equipment having 12,000 pounds of payload. If we take the main fuel at 5000, the remaining 7000 could be in Aux tanks at about 1 pound of tank weight per gallon of tank, so we waste 1,000 pounds with aux tanks, leaving 6000 of fuel. 5000 main fuel plus 6000 aux fuel is 11,000 pounds available. At 9.5 pounds per NM, we can go 1157 NM to burn out, or 1075 with reserve.
Now, all kidding aside Hydraulic Palm Tree, when I post something, I'd fly it, and you can take it to the bank. I made a living doing this for about 30 years, there is no achievement in publishing numbers that don't work!
Regarding the brandy, I would suggest Bourbon, Kentucky bonded. Next time I'm in the UK, lets get you, Crab and me together, we can bore each other silly with figures, buy alternating rounds, and get brilliant!
