Eagle Ornithopter by Richard Etter Modellbau

  14 Mar 07 - Flapping link failure.

Eagle drive link 1 Eagle drive link 2

N of launches / Time 27 0 hours 10 mins  
Wingspan - Varies 39.8" to 46.9" 101 cm to 119 cm
Wing Area 375 in 24.2 dm
Flying Weight 14.8 oz. 420 g 17.6 oz. 500g*
Wing Loading 5.7 oz./ft 17.3 g/dm 6.8 oz./ft 20.7 g/dm
Wing Cube Loading 3.5 - Glider - well it should be a feather-weight J 4.2 - Just above Glider
Motor Graupner Speed 300 6V, geared approx. 100:1 Park 370 brushless 4200 rpm/v
Batteries 8 AAA size 700mAh NiMH cells 3S1P 1600mAh FlightPower EVO20 20C cells.
Speed Controller Schulze slim-18be - 18/25A - 6 to 8 cells - BEC & Brake Budget Brushless - 15A - 2-3 LiPo - BEC
Receiver Schulze αlpha-435s - 4ch - PPM - 35MHz - Glitch counter
Servos Tail (Elevator) - Hitec HS-81MG
Tail (Rudder) - Hitec HS-81MG
Static motor parameters  With 8 NiMH 700mAh cells it draws 5.7A @ 6.4V and gives approx 5.6 BPS (beats per second). Not yet tested
Flight performance Not really flown enough to rate, see below. Not really flown enough to rate, see below.

14 Mar 07 - I fitted a brushless motor and LiPo pack to give the Eagle more power, which most definitely worked.   The weight above is with the side panels fitted and has gone up, but the power is much higher too.  However, flying today one of the ball joints on the wing beat crank "popped off", which results in a rapid descent, a bit like a brick.  I have bought some new ball joints which will hopefully be better and I'm trying to find some small rod ends that should be a permanent solution.

9 May 04 - Test flew today with a 2S pack of Kokam 1500HC LiPo cells. I managed to fly for over a minute on the first launch which is a marked improvement over previous attempts. It still needs a little more oomph, so I'm probably going to change the motor.

3 Mar 04 - I found information on the web about a wing speed of 5.6 BPM, which seems correct. I have a 2 cell (series) 1200 mAh Lithium Polymer pack that will easily take the current that this model wants and give much higher capacity of around twice the usable power, I'll have it give it a go once I've managed to test fly it on the stock system

21 Jan 04 - I completed this mode a couple of weeks ago and finally around to testing the set-up. I was trying to measure the wing beats per minute (BPM) but couldn't get a stable reading. I got to test fly it last weekend (18 Jan 04) but it would not maintain height and slowly descended to the ground, however, it looked very promising. Having studied the instructions some more it appears that the wing might be on the wrong way up, so I've flipped it over. Hopefully the next test flights will be more promising.

[Unorthodox Aircraft Models]