Multiplex Kranich

1 Jul 06 - Rudder issue added.

Multiplex Kranich Multiplex Kranich Multiplex Kranich Multiplex Kranich 

Number of launches 37 8 hours 59 mins
Wingspan 112 in. 2.85 m
Wing Area 852 in² 55.0 dm²
Flying Weight  7 lb. 7¼ oz 3.38 kg
Wing Loading 20.2 oz/ft² 61.5 g/dm²
Wing Cube Loading 8.3 - Between Trainer & Aerobatic
Motor Hacker B50 Short - 9 wind

Hacker 6.7:1

Propeller RFM 14.5 x 10 blades on Robbe hub with modified Aeronaut spinner.
Batteries 12 Sanyo RC-2000 cells
Speed Controller

Hacker (Jeti) 70-3P Opto - 6 to 16 cells, 70A, Brake, Opto-coupled


Schulze alpha-835s - 8 channel - FM - 35MHz

Receiver Battery 4 x 700 2/3A cells
Servos Ailerons (Spoilerons) - 2 x Multiplex Micro-BB Digi (Speed 0.18s/60°, Torque 48 oz. in., Dual BB)
Flaps (Flaperons) - 2 x Super FL BB Digi (Speed 0.20s/60°, Torque 28 oz. in., Dual BB)
Elevator - JR NES-810G (Speed 0.1s/60°, Torque 33 oz. in., High Precision, Top BB)
Rudder - Hitec HS-300BB (Speed 0.19s/60°, Torque 43 oz. in., Top BB)
Static motor parameters  12 Sanyo RC-2000 cells gave 60.5A at 11.6V and 6200 rpm. Input power is ~ 700W or 94W/lb.
Flight performance Climbed away from a hand launch with no effort and the climb rate was approx 45° and very positive. It glides at a low sink rate and performs loops and rolls with little effort. The controls are very well balanced and positive, but it lacks enough rudder authority for stall turns.

1 Jul 06 - I have been practicing stall turns and the Kranich lacks enough rudder authority for them to be completed reliably.  I taped up the gap between the rudder and the fin, but this didn't improve the situation.  I will try to make a little more throw available, but it is limited by the fuselage design and linkage arrangement.  If this doesn't work, I may replace the rudder with a larger version.

11 Jul 03 - Added 2 photographs of the wing tip modification - see top of page or click fitted or removed to see the photographs. The winglet is held in place by a main carbon spar, a carbon incidence peg and some sellotape underneath. The carbon spar and incidence peg locate in plastic tubes glued into the foam core and a liteply rib in the winglet and wing tip. If you look at the 1st picture of the wing tip (winglet fitted) you can see the cut-line that is made to match the winglet. A 2nd cut was made between the outboard end of the each aileron and the centre of of the break in the leading edge. Doing this will allow a much longer plain wing tip extensions to be fitted in place of the winglets, as shown in the sketch of the wing tip modification - see top of page or click here to view the sketch.

9 Jul 03 - I managed to complete the test flight tonight and it flew really well (see above). It will take some time to get the mixes fully set-up, but it flies well with just the basic settings. I spotted that the rudder was a little sloppy after the 1st flight, which turns out to be the servo moving in it's mountings. I will have to correct this by changing the grommets and stand-offs before the next flight.

23 Mar 03 - I have completed the construction now, except for securing the battery and the C of G check. Converting the wings to add flaps was easy, but took quite a time to ensure the marking out was correct and in filling the cut edges with epoxy and micro-balloons. Using the Multiplex wing wiring set (Part# 8 5253) makes things easy as everything connects up when the wings are fitted to the fuselage - I've even ordered another set for my Reliant Stinson to make life easy. Hopefully I can get the C of G location set this week (with the battery packs)..

16 Feb 03 - I started construction yesterday and it is progressing well.

10 Nov 02 - I recently bought a Kranich (uncovered) kit as I wanted a large electric-soarer. I have decided that I will fit flaps to allow crow braking. I also bought the winglet kit as I think they look really good. The instructions for, and parts with, the winglets enable the winglets to be removed for transport, which is a good idea. I will, however be mounting the winglets in a different way to the instructions, as I want to be able to fit longer conventional wingtips as well. To do this I will be cutting the wings at the start of the wingtip sweep-back, which will allow the fitting of longer wingtip panels. I don't know what alternative tips I will make yet, but certainly 3m and possibly longer. A similar system is available on a number of full-size sailplanes, which fly with winglets at 15m span or straight tips at 18m span.

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