[3e] Merlin Autogyro

[Phaelen Bleux]

I must admit I had no idea how to approach the drivetrain of this aircraft. It seemed from the entry in Red Tide that it was mostly treated as a helicopter, so that's the tactic I used. However, it leaves me wondering if the output of the powerplant is supposed to be split between the lifting rotor and the push prop, and if the rotor should then be treated more like a wing and the push prop more like an airplane drive system. Suggestions?

Merlin GTS Autogyro
Designed, built and tested by Jim Montgomerie, the Merlin is a single seat autogyro with a an aluminum frame and Kevlar body. It is provided to the customer as an unfinished kit. The purchaser must provide an engine, propeller, instrumentation, and the top rotor. This allows each aircraft to be customized to the customer's exact preferences.
The Merlin has been flown extensively in the U.K., and holds several intra-U.K. endurance records for an autogyro.

Subassemblies: Body +1, 3 small wheels -2, rotor -2.
Powertrain: 30-kW improved TTR drivetrain with 30-kW improved HP gasoline engine, 2,000-kWs lead acid battery.
Fuel: 11 gallons gasoline in standard tank (Fire 11).
Occupancy: 1 XNCS.
Cargo: 0 cf.

Armor
All: 3/5

Statistics:
Size: 11'x6'x7½' Payload: 330 lbs. Lwt.: 649 lbs.
Volume: 25 cf. Maint.: 158 hours Price: $16,103

HT: 11. HPs: 19 Body, 2 each Wheel, 9 Rotor.

aSpeed: 90 aAccel: 1 aDecel: 13 aMR: 3 aSR: 1
Stall Speed: 0 (20).

gSpeed: 155 gAccel: 8 gDecel: 10 gMR: 0.5 gSR: 1
Take Off Run: 50 yards. Landing Run: 22 yards.

Design Notes:
Body is 25 cf; wheels are 1.25 cf; rotor is 0.5 cf. Structure is Extra-Light, Standard. Armor is Expensive Composite. Mechanical controls. Empty weight is 320 lbs.
Armor cost and weight was reduced by ½ since it only covers to pilot compartment. Design loaded weight was 601 lbs.; aSpeed 89 mph, stall speed 38, take off run 45 yards, landing run 36 yards. Real-world values were substituted for these values. Although the craft cannot stall (Stall Speed = 0), it cannot maintain altitude at speeds below 20 mph, which is noted above. The rotor does not generate enough helicopter lift to get the craft airborne; the rotor area was used in all performance calculations for stall speed and landing/takeoff runs. Aerial motive thrust was calculated as for a helicopter (1.6 x kW).