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According to my sources, the following applies: The Pima County Sheriff's Helio Turbine Courier @ 3888 # was airborne in 150 feet on a 105 degree day at Tucson's elevation, factor in the density altitude and you have a serious short field airplane. The gross for this Helio is at 4200 pounds, I'm told.. and that's in the "experimental" category. If these were in production with the RR/Allison C-250 (420 HP) you could very well account for 90-125 feet at lower elevations in cooler conditions. An H-295 1400 series with this mod would have twice the rate of climb compared to the Super Cub. The Cub could probably match the take-off numbers, but you do not have useful load or minimum turn radius. The current fleet of 2 Helio turbines equals all the helicopters now flying in time on station, fuel burn, efficiency, and reliability. Acquisition costs would be substantially higher of course, but compare this to a MD-500. Cruise at 12,500 feet dials in at 145- 155 KTAS with power and torque around 350-370 HP..
There is always the STC route, but quite costly and time consuming!
Howdy Cstol,only 14 years old? Awesome to have that interest in aviation, and to ask questions like this. I was doing the same when I was your age, but that was 14 years ago, and the internet didn't offer the resources it does now. The STC route that Mr. Helio was talking about is a Supplemental Type Certificate. This is where someone comes up with a modification to a certificated aircraft, and then does the necessary engineering, testing and paperwork and gets an approval from the FAA for the modification. They can then usually use the STC on other examples of the approved model of aircraft (or sell the stc to other owners who want to do the same modification). It is a LOT of work to do, but it greatly simplifies the approval process for subsequent applications of the same modification.Bill
I was fairly knowledgeable at 14, but then when I started flying it took on a whole new perspective. Good that you ask now. The empty weight on the Helio 800 N400HE I'm not sure of, when they first got it, it was disassembled and the turbine was installed. For numbers here is what you have, The H-800 is typically 2700 pounds empty with the Lycoming IO-720 (400 HP) and the weight of the engine around 470 pounds. The RR/Allison is a mere 220 pounds or so, you just knocked off a lot of weight up front. We now have 420 HP with half the weight. Originally it was tail wheel and almost too light with all the torque and power up front. The decision to convert to tri-gear was an economic move, easier to check out pilots versus cost of operations. The installation of the turbine was borrowed form the GAF N-24 Nomad built in Australia. The other one N613SD has the same set up. Early in the test flight phase the H800 ate tires up to the amount of 4-5 per week, too costly, so this was the other factor in making the decision to go tri-gear. N400HE also has air conditioning..
Here is the current Helio H-800 after flight testing, it is also equipped with air conditioning and a Glass Panel