Continous run test for 6:00 minutes

One of the most important test was conducted today, the continous run test. I started full throttle with nearly full batteries to check the power consumption of the motor and the heat dissipation.

The result is very convincing: at full throttle with the 30" propeller I operated the motor for exactly 6:00 minutes. The cells were depleted afterwads to 22.7V that means 3.78V (LiPo 6S).

That is a fairly good value and there would be still some reseserve power. As the cells had seen some short tests before, I estimate the total operational time of about 7:30 minutes.

That is also more than initially expected.

The ESC has a shut-off controll for low voltage to protect the battery, so there is no problem of damaging it with to low voltage depletion.

Another important point is the temperature disipation. I checked with an infrared thermometer and the motor housing is getting to 78ºC at the end of the test. The power cables are also getting warm, around 40ºC. The battery itself only changed to 35º, also the electronics is not getting any warmer.

Static thrust on ground

I measured the static thrust on ground with a normal digital scale. The measured result was 10.1kg with the 30" propeller and unbelievable 14.9kg with the 40" propeller.

From the photo you can see that the axis has a inclination of about 25º. That means the real thrust in propeller direction is about 10% higher: 11kg for the 30" and 16,5kg for the 40".

That is far more than I expected for the 40".

Measurement setup with a sand bag to avoid the movement of the housing on the scale:

Propeller

The standard propeller for this electro  motor is a 30x8 inch plastic propeller. That is a diameter of 80cm. As the effectiveness of a motor depends on the propeller diameter, a larger one would be more apropriate.
For this reason I converted a 30 inch propeller with carbonfiber tubes to a 40 inch propeller, 101cm.
The thrust of the 30" should be about 120 N, increased with the 40" to 150N, nearly 15kg.
The propeller is well balanced and does not produce vibrations at higher RPMs.
Here is the comparative photo:

Next Steps

The first trial with full throttle was successfull. For about 30 seconds I switched on the motor mounted in the Swing Connect Reverse harness. The thrust is about 10kg as expected, an exact measurement will be done later.
But I have to modified the electronic box. Right now the control (an Arduino Uno board) is placed in an experimental plastic case. The wiring has to be more robust to prevent the cables to get loose.
In the next days I expect the new components and switches.
I will also replace the 9V battery as power source for the Arduino board with a BEC connected to one of the main batteries.

Throttle control

The throttle control is a modified comercial throttle. Unless a gasoline powered paraglider, the throttle is not operated with the fingers. The throttle is controled with the thumb which is far more effective and allows to use the throttle grip as brake handle.
The throttle/brake can be mounted parallel to the normal brakes. So in normal flying conditions you use the normal glider brakes and when you change to motor-mode you simply grap the throttle/brake handle and push the throttle with the thumb.

Her some pictures of the throttle before and after attaching it to the brake handles:

Battery pack

The battery pack is stored in a Lipo-Save bag for safety reasons. The bag is attached with velcros on a sports vest. The battery pack weights only about 2kg in the basic configuration.
If a problem with the battery occurs in flight (overheating/fire), it can be easily desconnected with a handle and thrown away (no mini-parachute installed yet).