|Sep 07, 2009, 05:03 PM|
C-ARF Extra 330L electric
This blog will be used to document the build and testflying of my Composite ARF EXTRA 300L.
A thread will be made in parallel for comments from you all and for me to ask questions when I run into problems to decide or find the best
|Sep 07, 2009, 06:23 PM|
Open the box
All the composite parts.
Nothing else have arrived yet.
Motor will be Plettenberg Predator 25-8.
ESC Schulse XL 40.160
Battery 11s7150mAh EON-X30.
Hitec HS-79xx servos (type not decided yet)
|Sep 07, 2009, 07:07 PM|
Planning the CG
The weights of the parts out of the box:
PART__________________MASS(gram)____CG in relation to tube centerA total of 5425 gr.-- A little more than expected but I have ordered carbon wing tube and carbon wheel pants from GraphTech, maybe save me 100 gr.
The HW kit and wood kit contain more than I will use too, includingalso some scrap.
The motor dome is one massive b-stard, I will throw it away and build
a hypostatic carbon framework. Target is to get rid of 50% of the weight.
Last, the gear legs is far to rigid for my taste. Will make new. Slightly
higer and with more flex. Target is 200 gr.
CG of the kit right now is -166 mm (behind tube center, I think center of tube
is a proper CG location but have not checked yet)
Adding 1500 gr motor-prop-spinner in the front gives me -26 mm.
I'm not worried at the moment, 2.5 kg battery to adjust with should do the
|Sep 08, 2009, 12:24 PM|
Have you tested how much thrust the Predator 25-8 will produce on 11 and 12 cells. I am planning on building a Hangar-9 Extra 260 (35%) for IMAC. I am aiming for at least 50 lbs of thrust on 12S. I an also trying to limit the batteries to 4 6S-5000s (12S2P) I am hoping that 10000 Mah will be enough for IMAC Sportsman.
|Sep 08, 2009, 02:07 PM|
Estimated data power system
By interpolating and extrapolating a number of prop data from Plettenberg
I predict this for a RASA 25x12 folding on P25:
Voltage: 41,8 V @ 20C (3,8 V/cell)
Revs: 6500 rpm
Thrust: 185 N
Current: 140 A
Input power: 5852 W.
In level flight I hope to gain a speed up to maybe 6900 rpm.
Gives a pitch speed of about 124 km/h.
I'm looking for both speed and thrust.
More thrust by choosing 26" or 28" prop doesen't makes sense
as I estimate all up weight 9.4 - 9.7 kg.
The motor is good for more but choosing the 250 gr lighter Terminator 30-8
had probably only caused me CG trouble. Now I have a motor that might fit also a 100" aerobat.
|Sep 10, 2009, 02:32 PM|
Stuff coming in soon..
Servos have arrived.
2 x HS7955TG for aileron
2 x HS7975HB for elevator (those are up-rated to 10.2 kgcm@6V, when did that happen?)
1 x HS7955TG for rudder
Predator 25 is shipped an will arrive Monday.
But I'm away from home until Wednesday
Still waiting for LiPo's (backorder)
|Sep 10, 2009, 06:26 PM|
It sounds like the 25-8 won't be enough for my application (35% Hangar 9 Extra) as 50lbs of thrust is roughly 225 Newtons. I look forward to seeing the progress on your project.
|Sep 15, 2009, 05:46 PM|
|Sep 17, 2009, 07:50 AM|
Predator has landed!
A first cell phone shot, more will come!
motor: 1294 gr
prop: 68 gr
spinner: 118 gr
diameter of mounted prop becomes 650 mm (25.6")
but it is named 25"x12". I guess effective pitch will also be a little
|Sep 17, 2009, 07:58 AM|
Trial fit of the EXTRA
Everything fits so far, on my way to pick up a carbon wing tube and wheel pants now. (neither of supplied as standard...)
The yellow machine down right in img is the genset for charging in field, more about this later.
|Sep 20, 2009, 06:02 PM|
To start with, carbon pants and wing tube received.
Pants were 68 gr, saving of 27 gr not much but the look cool too
Carbon tube weight 200 gr, 135 gr saving!
Started today with the cowl, I will let the cowl carry the motor and use
no dome at all!
First I fit a former in the rear of the cowl, then I make some reinforcements rear to front and put a plate in the front and finally I mount the motor on short stand offs.
So far only the former in place, solid 3 mm ply but it will be lightened of course.
Had to glue it with laminating epoxy+micro ballons+ground carbon fiber as my 30 min epoxy got very thick, don't know if it works any longer.
|Sep 21, 2009, 04:34 PM|
Received the AC-charger today.
Rated 18 A up to 15 LiPo. (1200 W)
A pure industrial device, to be programmed once for 1 type of battery.
But I purchased the programmer and software in case I want to change.
Weight is 3,6 kg.
|Sep 21, 2009, 05:09 PM|
Another 7 kg box hit the bin...
Contained a few LiPo's...and a nice ESC .
The Schulze ESC xl-40.160 offer a lot of features:
* Built in single cell voltage monitoring and logging.
* Dual temperature sensor inputs (motor + battery) both logged
* Hall sensor input for prop positioning and/or logging of speed of other device(prop can be braked in horizontal position)
* Current log
* Total voltage log
* Throttle position log
* ESC temperature log
* Motor speed log
All read over USB or RS-232
|Sep 21, 2009, 06:09 PM|
You have some very interesting electronics here... especially that charger. I assume it charges in series and not each individual cell?
|Sep 22, 2009, 04:25 AM|
The charge cycle can be divided in up to 5 phases.
For each phase, max voltage, max+min current and time limit can be set.
Conditions to go to next phase can be current < I(min), Ub>Umax, time out, capacity limit etc.
For each phase, the LED's can be controlled.
Global parameters can be minimum start voltage, voltage drop compensation (long cables) and temperature compensation.
Data about the last 32 charge cycles are automatically stored in the charger and can be read over the USB interface.
Balancing has to be done with auxillary device, I use the Schulze LiPoProfiBal-14 for this. But I see no need to balance all the time, that can be done back home.
This charger should be used if you want to FLY a LOT and want to reduce the number of
devices to connect and carry to the field. But of course, 230 VAC is needed, I bring my 1 kW generator if the field doesn't offer a power grid.
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