Switchblade by Cavazos Sailplane Design

30 Dec 01 - Modified to take 3S A123 LiFe cells.

N of launches / Time 9 0 hours 31 mins
Wingspan 27 " 68.6 cm
Wing Area 118 in 7.6 dm
Flying Weight 1 lb. 1 oz 0.488 kg 1 lb. 1.3 oz 0.491 kg
Wing Loading 21.0 oz/ft 64.2 g/dm 21.1 oz / ft 64.5 g/dm
Wing Cube Loading 23.2 - Racer (and some) 23.3 - Racer (and some)
Motor Hacker B40 16W-Short brushless Hacker B40 16W-Short brushless
Propeller Graupner CAM Speed 5" x 5" Graupner CAM Speed 4.7" x 4.7"
Batteries 7 Sanyo 500AR 3S A123 LiFe 1100mAh cells
Speed Controller Jeti JES 30-3P brushless 30A - 6 to 10 cells - BEC & Brake Jeti JES 30-3P brushless 30A - 6 to 10 cells - BEC & Brake
Receiver Webra Nano S6 - 6ch - PPM - 35 MHz Webra Nano S6 - 6ch - PPM - 35 MHz
Servos Ailerons - Hitec HS-55 Ailerons - Hitec HS-55
Elevator - Hitec HS-55 Elevator - Hitec HS-55
Static motor parameters  7 Sanyo 500AR give 17800 RPM @ 7.0V drawing 15.5A (108W), input power 100W/lb. 3S A123 LiFe 1100mAh cells give 19500 RPM @ 7.9V drawing 17.8A (140W), estimated 129W/lb.
Flight performance This model is FAST but flies like it's on rails, carving it's way through the sky with ease.  Launching can be tricky in calm conditions; some more power would help with that.  Due to the tiny frontal area it can disappear from sight when travelling directly away from or towards you; a little up elevator helps to show some of the wing chord when this happens.  It also glides a long way once the power is turned off and landing approaches have to be accurate if you're not to overshoot. Yet to be flown

30 Dec 11 - I have just finished converting the model to use a 3S A123 (18650 size) pack of 1100mAh  capacity.  The weight has increased by a few grams but I'm not bothered about that as the power/weight has increased by 29%.  These cells are slightly larger diameter than the original 500AR cells but only by 1mm.  The new pack in is a tight squeeze, mostly due to the length and getting it in is fiddly.  The 5th photograph shows the pack in place before connecting the power leads, which are pushed in to the fuselage in front of the pack.  The aileron servo lead is also visible and the connector is tucked to the side of the single (rear) cell once plugged in.

6 Sep 01 - I have just finished the model and it is ready to fly. The battery is right back against the elevator servo to obtain the forward most CofG quoted. I think that I'll need to get an 8-cell pack to move the CofG a little more rearward. I've added a few another couple of pictures above. The 4th picture shows the arming switch I fitted instead of the original one fitted to the Jeti controller. It is a small latching push-button double-pole switch that is mounted so the button is flush when armed, and protruding when safe. The use of this switch and countersunk screws to mount it causes almost no drag.

16 Jul 01 - I have been test running the motor, with a Graupner CAM Speed 12cm x 12cm (4.7" x 4.7") propeller, for the last couple of days and have posted the figures above. I estimate that the current will increase to about 18.7A with a 13cm x 13cm (5" x 5") propeller, maybe I'll give that a go tomorrow.

2 Jun 01 - Brushless motor it is, and I picked up the Hacker brushless motor and Jeti speed controller today from Gordon Tarling. This Hacker motor can be bolted in as a direct replacement for a Speed 400 motor in most models as it is the same mounting holes, is the same diameter, but 5mm (3/16") longer. These motors and controllers have an excellent reputation and should really make the model move. I cheated in the kit of contents photograph above as I show the wing twice (you only get one). This was to allow illustration of the pre-painted upper surface and carbon reinforcement on the underside. The hardware pack is extremely complete with the motor mount all the mounting hardware (including motor bolts), clevises and rod need to complete the kit (I forgot to put the elevator pushrod in the photograph). It even came with a spare wing bolt.

25 Feb 01 - The kit comes in many forms, but I chose the Carbon version with pre-painted fuselage & wings. The kit contains a white pre-painted epoxy-glass fuselage, white / red pre-painted foam veneer wings and white glassed pre-painted balsa tail surfaces. I opted for the Carbon version because I haven't decided what power system I want to use. I am torn whether to build with a standard Speed 400 motor, or to fitted a small brushless motor.

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