RHTizzy's blog archive for August, 2012 - RC Groups
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Archive for August, 2012
Posted by RHTizzy | Aug 31, 2012 @ 04:56 AM | 4,023 Views
Apart from the obvious safety aspects, incorrect prop choice probably causes more problems in electric flight than any other mismatched component, and it is SO easy to get right, as long as you have the correct equipment.
The equipment Iím referring to is some sort of measuring device such as a Wattsmeter or Power Meter, and these are available from most model shops now at very low cost.
There was a time when even I used to poke about in the dark, trying to establish whether or not I had chosen the correct prop by how hot the motor or NiCad pack got after a couple of minutes! Looking back it was crazy!
When you consider the cost of a melted motor, blown ESC or overloaded Li-Po, paying around £25 for a meter suddenly fades into insignificance and your enjoyment and success in electric flight will suddenly take an upturn, as you will finally be able to see at a glance exactly what is going on.
These meters simply plug in between the flight battery (whether it be a NiMh or a Li-Po) and as you open the throttle of your (well secured) model to full, the various readings instantly indicate the important information you need: current in Amps, power consumption in watts, battery state under load in volts, and in most cases the number of milliamp-hours of battery capacity given up (although this will only be of any use if you are measuring a complete ground run from fully charged to fully exhausted).
As you analyse this information, you can see whether the wattage exceeds the motorís capability, whether the current exceeds the ESC or batteryís constant handling capacity, and whether (in the case of a Li-Po) the battery voltage is being pulled down too low by the current being drawn. It is therefore also very useful in establishing the quality of some of these unknown brands of Li-Po from the Far East - if at 10C it is showing less than 10 volts, then your Li-Po is a lemon.

By Nigel Hawes
Posted by RHTizzy | Aug 31, 2012 @ 03:15 AM | 3,964 Views
For multicopters we typically all use lipos. The ESCs must be set for NiMh and no or soft cut-off because this makes the ESC low voltage cutoff lower so one or more of them does not decide to shut down in-flight which is always predictably bad ju-ju for multicopters. A throttle surge can be enough to momentarily put an ESC in shutdown mode if the ESC lipo setting is selected. Get a separate lipo alarm and gauge your total flying time minus two minutes reserve power for landing are the best practice methods for multicopter lipo management.

by jesolins (Jim)
Posted by RHTizzy | Aug 30, 2012 @ 01:00 PM | 3,983 Views
From what I gather I have more lift than I need as the current build comes to a total of 750gr

I found these specs:

Order No. - Model No. - KVRpm//v - Weight - Motor Dimensions - Shaft Size - Prop/ recom - Battery - Idlecurrent - Loadcurrent - Power(Watt) - ESC(A) - Ri (Ω) - Pull (Approx)

221215 - A2826-15 - 930 - 50g - Ф27.7*26.3mm - Ф3.17*37mm - 9x6/9x3.8 - 2-3Li-Po - 0.4A - 9.5A - 100 - 30A - 0.139 - 330g

So I was thinking I might try these should have enough lift if I stay under a kilo and would also give more airtime per battery
220414 - A2812-14 - 1400 - 22g - Ф28*11.5mm - Ф3.17mm - 6030/7040 - 2-3Li-Po - 0.4A - 3.2A - 60 - 10A - 0.270 - 200g

They probably wouldn't handle as well but I'm not sure what would happen and I've no idea whether I'd like it or not...
Posted by RHTizzy | Aug 29, 2012 @ 03:43 PM | 3,570 Views
Finished building and got the first opportunity today to try and get it in the air. But no such luck, it appears as if there's not enough power to get the quad airborne. Increasing throttle to max just gives enough power to hop a a few centimeters off the ground.

I got a 'pre-selected parts' beginner's kit from RCTimer so I had the least chance of mismatching stuff but it's using RCTimers 2200mAh 15C batteries which were the highest capacity they had available and I'm thinking they just don't have what it takes. I did use the online RC calc to check but is wasn't possible to fill in exact matches to my kit so I'm unsure about the results.

A few good idea's have come up, e.g. that it could be vibrations, but also that the ESC's might not be calibrated properly. People say it's doubtful that the battery is not powerful enough but opinions differ and some say 15C is barely enough and only on a new battery (which wont last long).

I haven't balanced my props properly so they might well be the cause of it. I hope to find some time soon to get it done and check whether that solves it.
Posted by RHTizzy | Aug 28, 2012 @ 03:38 PM | 4,694 Views
Bluetooth Module must have a Baud of 115200bps to connect
Bluetooth should connect to FTDI port (Tx/Rx3) (5v-5v, GND-GND, TX-RX, RX-TX)
When you want to send a new firmware you must unplug the BT to connect USB for uploading it.
MPNG - set appropriate port speed in APM_Config.h

Posted by RHTizzy | Aug 28, 2012 @ 03:19 PM | 4,024 Views
Posted by RHTizzy | Aug 28, 2012 @ 03:13 PM | 4,744 Views
if you power the board from external power source via the extended power in marked on the back of the board then you will be able to take power from the S1-S3 plug (so you dont have to have wires running from the I2c plug). The power supplied to the external power source is the power supplied to the S1~S3 plug so beware what voltage you connect.

Remember to remove the yellow jumper if you are powering the board this way

I connected a two pin header to the "EXTEND POWER IN" & removed the yellow jumper. With this set up you don't have to remove the BEC's (red wires) from the ESC's as removing the yellow jumper has cut them off from the rest of the board, also this means that there is power to "S1~S3" port (eight pin serial port as stated.

I used a 5A\5V UBEC directly off the batteryconnector on the frame which should provide ample power for the CAIOP and supporting modules such as Bluetooth, GPS or sonar.

I soldered 4mm bullet connectors to the frame for the ESC's so if anything needs to be replaced I can just disconnect it. I also soldered the UBEC directly to the frame and it gets it's power from the same connector as the ESC's. To connect the battery('s) I soldered both an XT60 and a Deans plug for convenience. As the Deans are not easy to work with, since then I've replaced them on all of my batteries with XT60's.

As it made more sense (and provided easier access) I soldered all my connectors to the bottom. As this might result in issues out in the wild, I added some hotglue for protection

Posted by RHTizzy | Aug 28, 2012 @ 02:48 PM | 3,793 Views
The following code will write the contents of the Crius AIOP compile to a binary. It is based on the arduino-0022 ide and your location will probably differ. As it's a binary it difficult to decompile but I've also added the code to write the compilation back to the board.

Read sketch
G:\>avrdude -C "G:\Devices\ARDrone\arduino-0022\hardware\tools\avr\etc\avrdude.conf" -v -v -v -v -p atmega2560 -c stk500v2 -U flash:r:"g:/arduino.bin":r -P\\.\COM8 -b115200

Write sketch
avrdude -C "G:\Devices\ARDrone\arduino-0022\hardware\tools\avr\etc\avrdude.conf" -v -v -v -v -p atmega2560 -c stk500v2 -U flash:w:"g:/arduino.bin":r -P\\.\COM8 -b115200
Posted by RHTizzy | Aug 28, 2012 @ 02:32 PM | 5,153 Views
Originally Posted by RHTizzy View Post
Okay did some digging and can report the following: it's definitely not just the ublox that suffers from the reset issue. In fact as far as Ive gathered most gps modules don't hold on to their settings indefinitely unless flashed and most are sold without any user flash cycles left. More on point, the LS20031 is an mtk3339 and eosbandi's gps sketch includes a comment that it's only good for the mtk3329. There are people who have claimed to have the 3339 working in binary mode but they are not specific about what it is they've got working. What I (and I'm sure others like me) are looking for is the ability to initialise the mtk339 on fc boot so it isn't reliant on user settings or the battery to hold on to the appropriate baudrate and nmea sentence settings. As it is, it works in nmea mode and will report it's position to the fc but it's far from optimal as far as cpu load goes and has an appaling accuracy regardless of the number of sats fixed...
After some extensive research, the following works for the Locosys LS200031 with MT3339 chip and will initalise the GPS module on boot regardless of default settings or default speed. It will reconfigure the GPS unit to 115200bps, 10Hz, with GGA+RMC NMEA sentences (minimum needed but I also added GSA so miniGPS can utilise the data).

No need to replace the GPS.ino, just add the following code in the GPS sketch in the section that...Continue Reading
Posted by RHTizzy | Aug 10, 2012 @ 09:03 AM | 5,885 Views

RM450 Kit
  • Package:
  • Wheelbase: 17.7in/450mm
  • Weight: 0.65lb/282g(Appr)
  • Made by advanced engineering material, super strong & smooth.
  • Black color
Crius All in one Pro

...Continue Reading