Simprop Excel Competition

7 Apr 00 - Converted back to a kit.

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Number of launches 48 20 hours 2 mins Note: Not all flights included
Wingspan 87 in. 2.21 m
Wing Area 564 inē 36.4 dmē
Flying Weight 3 lb. 5 oz 1.50 kg 3 lb. 13 oz 1.730 kg
Wing Loading 13.5 oz/ftē 41.2 g/dmē 15.6 oz/ftē 47.5 g/dmē
Wing Cube Loading 6.8 - Trainer 7.9 - between Trainer & Aerobatic
Motor Graupner Speed 600 Race 8.4V retimed for reverse rotation Simprop 1500-10 - 10 cell motor
Gearbox Graupner FG3 with 3:1 ratio.
Propeller Graupner CAM 14 x 9.5 blades on Aeronaut hub & spinner.
Batteries 7 Sanyo RC-2000 cells 12 Somoso 1800mAh cells
Speed Controller

Gordon Tarling Micro-Star 40BEC/B - 6 to 10 cells, 40A, BEC & Brake

Graupner Power MOS 48


JR NER-649R - 9 channel - S-PCM - 35MHz

Receiver Battery None 4 cell 650mAh
Servos Spoilerons - 2 Fleet FPS-15 micro
'V' Tail - 2 Fleet FPS-15 micro
Static motor parameters 

Graupner Speed 600 Race on 7 cells - 4300 RPM at propeller drawing 23.6A after 30s.

Simprop 1500-10 on 12 cells - 4100 RPM at propeller drawing 14A after 30s.
Flight performance General - The model flies very well and is well balanced in it's controls. I can quite happily perform loops and chandelles, but other aerobatics are limited by the control authority of the 'v' tail. I can land the model very precisely due to the spoilerons. I model I would recommend for any modeller looking for a good all round electro-soarer.

Graupner Speed 600 Race on 7 cells - Climbs quicker than on 12 cells (much lighter) and it soars better due to the reduced weight. However, the motor run is much reduced and only 5 minutes is now available, but the total flight time remains much the same.

Simprop 1500-10 on 12 cells - Approx. 20° climb. Duration 25 minutes + in still air.

The wing section is built up to Selig 3021 profile with the micro servos mounted in the wings for ailerons. These are electronically mixed to allow the ailerons to be lifted to act as spoilers. The fuselage is a glass-fibre moulding and pre-finished in while gel coat. The 'V' tail sheet balsa and is also electronically mixed using 2 micro servos. I intend to experiment with the fitting if a conventional or 'T' tail for aerobatic use.

The motor batteries are fitted directly on the C of G. This allows fitting of different capacity cells without affecting the CofG position. It also allows the glider to be flown in light lift on a slope without them reducing the flying weight to 40oz and the wing loading to 8.9oz / sq. ft.

20 Sep 98 - I haven't used the model in a few months as it has been far too windy when I've been able to fly. I rigged and tested the controls which all worked fine until I attempted the start the motor. Initially nothing happened and on the 2nd switch on the motor ran for about 1 second and stopped. After numerous similar runs I decided not to fly & check out the problem. After the problems the day before with the Cub speed controller I am getting extremely fed up with controller problems.

I have been experiencing problems with flutter of the starboard wing. I originally put it down to the starboard aileron being less rigid which I discovered when I compared the two ailerons. However, I was still experiencing problems today after having stiffened the flexible aileron with injections of cyanoacrylate. On a closer examination of the wing panel I discovered that someone had dropped something on the D box at about 25% span. This reduced the torsional strength of the wing and was allowing the flutter to occur. The flutter has caused some other damage to the D box due to the flexing of the wing. I have inserted a small replacement piece of balsa in the damaged area and applied cyanoacrylate to the other area to rebond them. This is only a temporary repair as the wing really needs the D box top sheeting replacing for the whole panel. I have been considering making a new set of wing of a larger span, probably between 2.5m to 2.75m. Now seems a good time to do this instead of repairing the existing wing. I intend to use a custom foam core with a lot of lightness built in. To illustrate the point I have sketched up the proposed wing with lightening holes.

8 Aug 99 - Yesterday I flew with 12 RC-2000 cells and managed to overspeed the rewound Simprop 1500-10 motor. As I wanted to practice for the Electroslot competitions I decided to convert the model to 7 cell operation. As I have a few I decided to use a Graupner Speed 600 Race 8.4V motor. Unfortunately these have very advanced timing for forward rotation and I needed to run it in reverse because of the gearbox. I therefore opened the case, cut new backplate retaining tabs in the can in the reverse rotation position and reassembled the motor.

7 Apr 00 - Whilst flying today I had to take my eyes off the model due to an errant model flown by somebody else (potentially going to hit me & several others). I never managed to locate the model again until after it had been on the ground for some minutes. The impact snapped one wing, ripped the tail off the fuselage & shattered the nose of the fuselage. The model was well beyond repairability & has been scrapped.

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