Difference between revisions of "Sumo"

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= SUMO =
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= About =
 
The SUMO is an aircraft build by the Geophysical Institute of the University of Bergen, Norway.
It uses industry standard sensors for temperature, air pressure, humidity and wind speed/direction as well as more specialized sensors as infrared/visible light radiation, particle concentration or ionizing radiation (full list). It has been successfully used in many measurement campaigns by various research institutions.
 
= Specifications =
 
= Mass =
 
Provided below are some weights to aid in estimating an all up weight for your UA
 
* Tiny13 1.1 Weight: 25g (0.88oz)
* IR Sensor Head: 5g (0.18oz)
* XBee Pro: 4g (0.14oz)
* Hitec HS-55 Servo: 8g (0.28)
* Brushless Outrunner 250W: ~90g (~3oz)
* FunJet assembled, no hardware: 165g (5.82oz)
* FMA Encore 5ch Receiver: 11g (0.40oz)
* Castle Creations Phoenix 35: 24.5g (0.9oz)
 
= Airframe file =
 
= Misc Airframe Notes =
 
[http://www.motocalc.com MotoCalc] is an Electric Flight Performance Prediction program for Windows and is available for a 30 day free trial.  MotoCalc has an internal database of thousands of motors/props/etc. and can make power/flight predictions based on data input.
 
[http://brantuas.com/ezcalc/dma1.asp Electric Motor Calculator] by Diversity Model Aircraft is a free online tool for matching props to motors to batteries.
 
[http://www.gobrushless.com/testing/thrust_calculator.php?prop=45&rb1=1&Value=9720&submit=Calculate+Now Propeller Thrust Calculator] is a free online calculator to give thrust from given propeller and RPM or vice versa.
 
[http://www.hanleyinnovations.com/multisurface MultiSurface Aerodynamics] is an airfoil and wing analysis software package. The software predicts lift and drag for multiple interacting wings.
 
== Battery Specs ==
 
'''Nickel Cadmium (NiCd)'''
 
* Energy/Weight: 40-60 Wh/kg
* Nominal Cell Voltage: 1.2V
* Fully Charged Cell Voltage: 1.2V
* Depleted Cell Voltage: 0.8-1.0V
 
'''Nickel Metal Hydride (NiMh)'''
 
* Energy/Weight: 30-80 Wh/kg
* Nominal Cell Voltage: 1.2V
* Fully Charged Cell Voltage: 1.35-1.4 V (unloaded)
* Depleted Cell Voltage: 1.0V
 
'''Lithium-Ion'''
 
* Energy/weight: 160 Wh/kg
* Nominal Cell Voltage: 3.6 / 3.7 V
* Fully Charged Cell Voltage: 4.2V
* Lowest Cell Discharge Voltage Before Damage: 2.4v to 3.0v
 
'''Lithium-Ion Polymer (LiPo)'''
 
* Energy/weight: 130-200 Wh/kg
* Nominal Cell Voltage: 3.7V
* Fully Charged Cell Voltage: 4.23V
* Lowest Cell Discharge Voltage Before Damage: 3.0V
 
'''Typical Power Requirements'''
 
* 70W/kg (35W/lb) for sedate flying from hand launch
* 100W/kg (50W/lb) for ground take off
* 150W/kg (75W/lb) for performance / aerobatics
 
=Building=
 
The installation of autopilot, sensors and modem is described here. More extensive building not needed if a ReadtToRun(RR) Funjet kit is ordered from Multiplex.
 
==Autopilot==
The image below shows a Tiny V2 installed in a funjet. The dual IR sensor is also visible.
[[Image:Tiny_v2_1_Funjet_install.jpg]]
 
==Sensors==
===Gyro===
 
The gyro should be mounted with the PCB perpendicular to the X (roll) axis of the aircraft. So the PCB should be parallel to the YZ plane of the aircraft. The rotation about the X axis is not important.
 
===IR===
The sensor FOV is typically around 60-100 deg, depending on brand.  Everything
emits heat, so you should try to keep the view as unobstructed as possible. 
There is of course no way to mount the sensors such that they are perfectly
unobstructed and a complex set of calibration factors exist in the code to deal
with this.  Just be sure to keep any obstructions symmetrical, particularly
difficult with pitch, and try to avoid having sun-heated surfaces in the FOV -
such as the top of a wing, tail, or fuselage.
 
Avoid placing sensors in the exhaust stream since oil buildup will certainly cause trouble and you may even have problems with hot exhaust. It's important to note that you cannot cover the sensors with any commonly available material - only very special materials will allow LWIR to pass.
 
Most importantly, keep any video/data transmitters away from the sensors and
their wires.
 
====Dual IR====
The mounting procedure of the Dual IR sensor is explained by the [http://www.fmadirect.com/support_docs/item_1049.pdf FMA CPD4 Manual] on pages 6 and 7.
 
Slightly different installation and setup procedures are explained on page 23 of the CPD4 Manual. For planes which:
*Have a low or mid wing, and exhaust flows under fuselage.
*Have a canopy.
 
====Single IR====
Mount the single IR sensor so that it is vertical when the aircraft is in level flight, and has an unobstructed view of the sky and ground. Helicopter blades will not obstruct the sensor's view.
 
===External GPS Antenna===
 
==Radio Devices==
 
Place transmitting radio devices (modems and video transmitters) as far away from receiving radio devices (RC receiver) as possible. The [[Hardware_Installation#General_Electrical_Advice|countermeasures]] to radio interference should be taken.
 
===Modems===
The picture below shows a modem install on a funjet, and the Dual IR sensor.
 
[[Image:PPZFJ01_install.JPG]]
 
It is ok to place the modem near motor and control. Do not place it near the RC receiver.
 
===RC Receiver===
 
Place the RC receiver as far away as possible from any transmitting radio device and from motor and control. On a pusher plane (Funjet) put it in the nose, on a standard plane (EasyGlider) put it in the tail. Especially if you are using older RC equipment (27/35/40MHz) this is important. Modern 2.4GHz RC is less prone to radio interference.
 
===Video Transmitter===
 
You will get best performance and least interference by placing the video transmitter as far away from any other electronical device, e.g. on the wing tip or in the tail of the plane. Especially if you are using a high power video transmitter this is extremely important.
 
==General Electrical Advice==
===Wiring Suggestions===
====Common Ground====
We had immediate success by connecting the motor chassis, the motor
mounting bracket, the minus of the motor driver supply, the minus of
the servo battery, the minus (ground) of the receivers onto a common
ground wire which we laid through the whole plane body from  tip to
tail.
Actually we use a braid from a shielded cable. Remove the insulation,
then push the wire mesh shield ends together which makes it easy
to slide off the cable, then pull to full lenght again. Finally the
mesh was about 5 mm wide flat litz wire. Alternatively one could use
thin copper tape which is available from electronics suppliers.
High frequency currents run on the outer surface of the conductors,
therefore it is important to have as much surface as possible on the
ground wires. Connect each metal part to ground, e.g. motor mount.
 
====Twisted Cables====
Twisting is almost as good as shielding.
Twisted cables normally do not have to be shielded in moderate
environments. How does twisting work?
 
The electromagnetic field induces interference currents in the wires.
By twisting the wires we change the polarity of the
induced voltages every  twist, and so the
disturbances cancel each other.
 
It is absolute necessary to twist the power cables
from the motor battery to the driver board, because
there run high pulsed currents and what is true for
reception, is also true for transmitting, and the
electric noise transmitted from the power cable will
cancel itself when run over twisted cables.
Needless to say, make the wires as short as possible,
from the battery to the driver to the motor.
Those components must be placed as near as possible,
especially the driver and the motor.
 
Always use twisted servo cables and remove those
3 pole flat cables from your design if possible!
 
====Ground Loops====
Grounding loops are not that much of concern as in audio
equipment or in microvolt sensors, but there is a general
simple rule to ground loops:  avoid them.
 
====Ferrite Beads====
 
I do not recommend the use of ferrite beads, because if I need them,
my basic design is flawed. Sometimes ferrites help to overcome
problems, but I recommend to correctly design and install wirings and
shields the proper way. For example, I would lay out the interior of
a sensor compartment with thin copper foil or mesh or spray with
conductive paint to get a shielded chamber. Of course, I must take
care to connect all shields to ground on several places.
 
====Preventing and Fixing Interference====
 
All small-signal cables should be shielded, power cables twisted.
Signal inputs should have small capacitors to ground for
HF filtering, or an inductor + cap or a resistor + cap.
Power cables must have HF capacitors on both ends!
Electrolytic caps are not HF qualified.
Cables could be connected via "feed through capacitors"
and loaded with  ferrite beads.
Ground connections between the boards should be short
and made of litz wires. Card cage should be lined  with
copper foil and connected to common ground on  many places.
And so on. Much to  be tried out experimentally.
 
I would start to shield and filter the most sensitive circuitry.
Find the point of maximal sensitivity.
Switch off and on the various transmitters to identify the source.
 
Wrap the boards in thin copper sheet, and so on.
Line the complete electronics compartment with thin copper
and connect to ground.
Put a conductive "ground plane" where the antennas are mounted.
Adhesive copper shielding tape is available but you must put
solder dots all over the tape joints. Conductive paint spray
is also available. Create a HF "zero reference" plane where all ground
connections meet. "Star" grounding configuration is less important
to HF designs, but we must avoid wire loops.
 
= Links =
 
[[Category:Airframes]] [[Category:Hardware]] [[Category:User_Documentation]]

Revision as of 15:20, 19 December 2019

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