EXPIRE, the quickly folding large quadcopter

[INAUDIBLE]

Updates:

29/12/2020] Canopy and clips added (+-30g).

This is Expire, any similarity to a big brand commercial quad would be only coincidental, it is a simple modular quadcopter which can be quickly folded for optimum compactness in transport despite its size.

With 15 "folding propellers: 440X240X230mm

The arms are held in position for flight by pins that are quickly insert and lock without tools.

The lower and upper plates are strictly symmetrical except for the size of the pre-holes respectively for the M3 inserts or the M3 screw heads. Even without exception if you are using M3 inserts with a diameter of 6mm (M3 heads are generally 5.5mm).

The integration of the screw heads in the frame allows easy use of the top plate for mounting electronics.

12mm aluminum tube arms were chosen, heavier than carbon certainly, but more solid and more accessible. In addition, the shape ensures a perfect fit between the plates.

The motor supports designed for a 4-hole M3 mounting with a 25mm diameter can be used as feet or 7.5mm square aluminum tubes can be inserted.

Mounting the camera on a rostrum towards the front should allow a comfortable viewing angle. Pay attention to the machine's balancing!

Weight of the whole frame with engine mounts but without feet: 356g

Feet 13cm under the tube mount X4: 449g (tarot 650 = 476g)

Printing in ABS (for temperature resistance), walls and top / bottom 0.8mm, 15% and 25% infill for motor supports (to be printed with the hole in the vertical arm and supports).

My personal configuration:

• Propulsion, 6S (2x3S) Ovonic 8000maH, ESC 2-6S 40A, racerstar 3508 380kv, 1240 prpellers

• Pixhawk, storm32 (powered by a 12V BEC).

• 2452g ready to fly

• Flight time (dynamic, in automatic mode most of the time) few more than 15Mins.

Detail of test, start from ground with 4.2V/cell, failsafe trigger at 3.4V/cell.

Propeller choice:

• 1447, hover at 19A throttle 14 to 18% (very low, quite dangerous!), 12 minutes flight time 4300mah used, climb like a rocket!

• 1240, hover at 16A throttle 20 to 24%, 15 minutes flight time 4300mah used, more stable!

After landing, 1447 props motors 42°c, 1240 props around 30°c resting voltage up to 3.7V/cell

Test with1447 props & battery 4S 5000maH :

• 2128g ready to fly, less stable but conditions was more windy

• 11 minutes 42s flight time, failsafe trigerred by mAh (4000 consumed) at 3.45V/C or 4316mAh over the whole flight.

• dynamic flight consumption 21A

• hover at 24.5 to 32% of throttle

As conclusion, 4S battery with more capacity could give better flight time, the additional weight created can induce faster propeller's ans could make the flight more stable, 8000mAh could be fine, even 2x 4S 4000mAh in parralel to secure the machine in case of lipo failure. 4S voltage allow to use the machine size with 14" props.

During this test I discovered that during 6S test failsafe was 3.4v/c but also 4000mAh (8000mAh battery!). So 0.8V are remaining to befre reaching 3.4v/c it could induce +700mAh usable and 2minutes30s of additional flight time, so 17m30s, that require test to validate it.

Possible enhancement :

• actual motors unavailable -> Racerstar 4108 380kv (low cost choice), others equivalent power motors, quality equal or better

• test with 1137 props

• branded propeller, with better quality/yield

• less powerful ESC (30A maybe 20A)

• better quality battery (tattu, genace, turnigy...)

• hood on the electronic

Other possible propulsion :

• use of lower kv motors that suit larger propellers than 12" with 6S battery

• use of 4S or 5S battery with the same motors to suit larger propellers than 12".

All included cost (copter with pixhawk, telemetry, gimbal, LIPO's, charger and remote control) approximately 400€.

[FR]

Update :

29/12/2020] Cover and clips added (+-30g).

Expire, any resemblance to a well-known brand name would be purely coincidental is a simple quadcopter that is modular and quickly foldable for optimal compactness during transport despite its size.

With 15 " folding propellers: 440X240X230mm

The arms are held in position for flight by lugs that can be quickly inserted and locked without tools.

The upper and lower plates are strictly symmetrical except for the size of the housings for the M3 inserts or M3 screw heads respectively. See without exception if you use M3 inserts with a diameter of 6mm (M3 heads are generally 5.5mm).

The integration of the screw heads in the chassis allows easy use of the top plate for mounting the electronics.

It was chosen arms made of 12mm aluminium tube, heavier than carbon, but stronger and more accessible. Moreover the shape ensures a perfect fit between the plates.

Motor brackets for 4-hole M3 mounting with a diameter of 25mm can be used as feet or 7.5mm square aluminium tubes can be inserted.

When mounting the camera on a rostrum towards the front, a comfortable viewing angle should be provided. Pay attention to the balancing of the machine!

Weight of the whole chassis with engine mounts but without feet: 356g

Feet 13cm under the tube and skates X4: 449g (tarot 650 = 476g)

Printing in ABS (for temperature resistance), walls and top/bottom 0.8mm, 15% and 25% filling for motor supports (to be printed with the hole of the vertical arm and supports).

My personal configuration :

• Propulsion, 6S (2x3S) Ovonic 8000maH, ESC 2-6S 40A, racerstar 3508 380kv, propellers1240

• Pixhawk, storm32 (powered by a BEC 12V).

• 2452g ready for take-off

• Flight time (dynamic, mostly in automatic mode) a little more than 15Mins.

Test details, takeoff at 4.2V/cell, failsafe at 3.4V/cell.

Choice of propellers :

• 1447, hovering at 19A gas 14 to 18% (that's low, a bit dangerous!), 12 minutes of flight 4300mah used, climbs like a rocket!

• 1240, hovering at 16A gas 20 to 24%, 15 minutes of flight 4300mah used, more stable!

After landing, propeller 1447 engines at 42°c, propeller1240 engines at about 30°c battery voltage at rest > 3.7V/cell.

Test with 1447 propellers and 4S 5000maH battery:

• 2128g in flight order the aircraft seems less stable but conditions are windier

• 11 minutes 42s of flight, failsafe triggered by mAh (4000 consumed) at 3.45V/C or 4316mAh over the whole flight.

• Average fuel consumption in dynamic flight 21A

• stationary from 24.5 to 32% of gases.

Conclusion, a 4S lipo of higher capacity could offer a longer flight time, the additional weight implying a rise in engine rpm would probably make the machine more stable, 8000mAh could be well to see 2x 4S 4000mAh in parallel which would secure the machine in case of failure of one of the two lipo. The 4S voltage makes it possible to exploit the size of the machine with 14" propellers.

During the test I discovered that my failsafe during the 6S test was 3.4V/C but at 4000mAh (battery 8000!). This leaves 0.8V/6elements=0.13V/C and allows to use 700mAh more or about 2m30s of extra flight according to the log, so 17m30s of autonomy, to be confirmed in test.

Possible developments :

• current engines unavailable -> Racerstar 4108 380kv (cheap choice), other engines of equivalent power, equal or better quality

• test with propellers 1137

• brand name propellers, better quality/efficiency

• ESC less powerful (30A see 20A)

• better quality drums (tattu, genace, turnigy...)

• electronics cover

Alternative propulsion :

• kv engine < to use propellers >12" always in 6S

• use of 4S/5S battery with the same motors to use propellers >12" always in 6S

Cost all included (drone with pixhawk, telemetry, gimbal, 2 LIPO, charger, remote control) about 400€.