[QUOTE=aviator;5271]hmm, interesting, first efficient helicopters were made because of the introduction of jet turbine engines, powered by turbo shaft, this engine has a large differences in terms of power to weight ratio…[/QUOTE]
As the RC Pilot Knows - Electrics are now taking more records for performance than the Glow Fuel models - and it is the Electrics that practically Invented ‘3D Flying’! The Ability of the Motor, Controller, and Battery to give Massive amounts of power for Bursts is what makes that happen!
Generally Speaking - Power needs are Greatest for Vertical Lift machines - like Rockets and Helicopters, followed by less (but still a fairly large power mass) for Winged Aircraft, going down to much smaller power needs for LTA (Light Than air) Aircraft like [B]Blimps or Dirigibles[/B].
Consider looking up X-Plane for your design tool - http://www.x-plane.com and connecting on Flightsim Community for X-Plane ®istering with other users. Headway Lithium Iron Phosphate Cells like the [B]Headway 40152S 15ah -screw tab[/B] are currently rated at about 100 Wh/Kg - while [B]Thundersky Cells - like the 100 Ah Cell are in the range of about 91 Wh/Kg[/B].
Looking at the Industrial 18650 Cells - Like Panasonic 3.1 Ah Cells takes things up a notch - at about 235 Wh/Kg - as Shown in the Specs - [B]Specifications For An Electric Motorcycle Pack[/B] - at NTS Works [Simply - minimum energy of 15.3 kwh divided by 65 Kg Cell Weight].
They are not the highest power of this type at present though, as there are now [B]available 3.4 Ah Cells - 3400 mAh - from Panasonic, available to buy - online[/B]! That puts these cells at 272 Wh/Kg [3.6V x 3.4Ah / 45gms].
Next up are the coming Cells from [B]Envia Systems - see the February Announcement[/B] - at 400 Wh/Kg, or the [B]August Story on GM using them, and availability in 2014 - 2016[/B] - if that is real!
That gives you some thought on Batteries, - or - you could use a bunch of RC Model LiPo Packs - Like the [B]World’s First Electric Amphibian[/B]!
([B]This GENS ACE 4S1P Pack Hard Case[/B] delivers just over 131 Wh/Kg though, but does have a very high ‘C’ Rating at 40 C Continuous - which is 4X Better than the Headway Cell above, and 13X Better than the ThunderSky Cells!)
Motors - The Ultralight turned to the RC Model world like [B]Dale Did for the Lazair[/B], or - but you might turn to either the Electric Car World - and a [B]new promising follow up motor - called the AC-75[/B], or to electric Scooters and their Hub Motors - like those found in the [B]ZEV 7100 Scooter[/B]! Go to about 2/3rds the way down this News page to read “[B]ZEV ENGINEERS BEGIN GENERAL AVIATION ELECTRIC AIRCRAFT MOTOR TESTING[/B]”!
Either Way - you have in mind a Chinook Style Machine - but a Budget Constraint might send you to a Fixed Wing Machine or other designs