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Flight computer

Mike15Mike15 Posts: 109
edited 2008-01-14 04:11 in Robotics
I have finally finished my rocket project. The attachments explain most everything.

If anybody has any suggestions or comments let me know.

Thanks to alll the people on this forum that have helped
doc
doc
Flight Computer+Mode of Oper..doc
2M
bs2
bs2
Rough.bs2
9K

Comments

  • BeanBean Posts: 8,129
    edited 2006-06-25 13:07
    Mike,
    · What battery do you use ?
    · Have you flown it yet ?
    · I'd love to see a data file if you have.

    Bean.

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    Cheap 4-digit LED display with driver IC·www.hc4led.com

    Low power SD Data Logger www.sddatalogger.com

    "I reject my reality, and substitute yours." NOT Mythbusters
    ·
  • Mike15Mike15 Posts: 109
    edited 2006-06-25 14:06
    I am using an N-cell battery.

    I was going to fly it fot the first time this weekend but the motors I ordered ended up being the wrong size. What a downer. I am re ording the motors so hopfully next weekend. As soon as I get some data I will post it.

    I am already working on a second version that will also have GPS, gyro and SD card reader/writter.
  • RinksCustomsRinksCustoms Posts: 531
    edited 2006-06-25 16:42
    Awesome work, how does the N cell hold up to a Basic Stamp? How long can it run before the battery goes dead?
  • Mike15Mike15 Posts: 109
    edited 2006-06-25 17:30
    It's works all right, but it wouldn't mind finding somthing that lasted a little longer. Thats why I added a power swithch so it can be turned of when returning to the launch pad.

    If anybody has a better idea on light weight battery let me know. As the N-cell needing to be replaced in about half the time of a 9V and at $6.00 a battery starts adding up.
  • Robert KubichekRobert Kubichek Posts: 343
    edited 2006-06-25 18:07
    Mike15 said...
    It's works all right, but it wouldn't mind finding somthing that lasted a little longer. Thats why I added a power swithch so it can be turned of when returning to the launch pad.

    If anybody has a better idea on light weight battery let me know. As the N-cell needing to be replaced in about half the time of a 9V and at $6.00 a battery starts adding up.

    Why don't you explore the possibility of using a lithium-ion rechargable???idea.gif

    The power-to-weight ratio is better than most other types, and it has no memory effects.

    You just have to make sure you use the correct charger....yeah.gif

    Bob scool.gif
  • GadgetmanGadgetman Posts: 2,436
    edited 2006-06-25 20:43
    Would a 100mA 3.7V Li-poly cell weighing in at less than 1gram be suitable? Or maybe two of them?
    It can even do a 6C discharge... (600mA for about 10 minutes)

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  • Timothy D. SwieterTimothy D. Swieter Posts: 1,613
    edited 2006-06-27 22:29
    What about capacitors? Use a larger enough capacitor, charge it up, then you might be able to do several runs,

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    Timothy D. Swieter
    tdswieter.com
    One little spark is all it takes for an idea to explode
  • RinksCustomsRinksCustoms Posts: 531
    edited 2006-06-29 04:10
    Li-Ion would offer huge capacity over an N cell, and mouser.com can supply a 5V 5 Farad capacitor! yeah 5 Farad, that should power your flight computer and periphials for about 10 min or better!

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  • 8Ball8Ball Posts: 2
    edited 2007-04-06 14:12
    solor cells would work good and they dont weigh very much heres some flexible ones http://www.siliconsolar.com/shop/catalog/6v-Flexible-Solar-Panels-p-1-c-308.html
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2007-04-06 15:47
    Be careful of those supercapacitors. They will cause huge current inflows [noparse][[/noparse]act like a direct short] unless limited by a resistor and backflows need to be blocked with diodes.

    Seems to me that two 3.0V Lithium cells [noparse][[/noparse]like the computer backup batteries] could be used with a diode to drop the voltage to 5.3volts. Then just skip the BasicStamps regulator. You really don't need the voltage regulator for battery operation anyway.
    These are cheaper and lighter, but they are not rechargible. At least you aren't dumping a lot of energy [noparse][[/noparse]the N cells are 12volt, right?] through the regulator.

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  • Dave HeinDave Hein Posts: 6,347
    edited 2007-04-10 16:47
    I think an N-cell is a 1.5 volt battery. At least that's what the Energizer.com website says. Click on the "Technical Info" link to get specs on various types of batteries. There is a 12-volt battery that has about the same dimensions as the N-cell, which is what Mike15 must be using.

    I noticed that the flight computer document shows an Aerotech Strong Arm rocket. This rocket weights 18 ounces without a rocket motor, and probably closer to 24 ounces with a motor. I would suggest using a Lithium 9-volt battery. The Energizer L522 weights 42.4 grams, which is 1.2 ounces. This is only 5% of the total weight of the rocket.

    I fly a rocket with a digital camera and controller powered by a 9-volt battery. This rocket is similar in size to the Strong Arm rocket and I have flown it many times with the camera payload. I would suggest adding a battery meter to your flight computer which would measure the voltage of the battery. This way you would know if it is time to change the battery.

    Dave
  • Mike15Mike15 Posts: 109
    edited 2007-04-12 01:59
    The N-cell is a 12 volt battery.
  • Paul BakerPaul Baker Posts: 6,351
    edited 2007-04-12 03:09
    That is why you have very short lifetimes, that battery is intended for use in remote keychains with only ocassional intermittant use. The average capacity is 33mAh, which is extremely small compared to the 1000mAh+ many rechargeable batteries have now. You would do much better using some 3V non-rechargable lithium coin cell batteries wired in series to achieve the voltage you need.

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    Paul Baker
    Propeller Applications Engineer

    Parallax, Inc.
  • Dave HeinDave Hein Posts: 6,347
    edited 2007-04-12 21:08
    Mike15,

    A 9-volt battery is a good match for a 7805 type regulator. A 7805 requires a minimum of 7.5 vollts on its input. Under "nominal" loading a 9-volt battery will produce a range of 8 to 9 volts during most of its life. The extra 3 volts from a 12-volt battery results in wasted energy.

    I understand the desire for a low-weight battery. I have a PerfectFlite altimeter that uses the small 12-volt battery, and I can get several flights out of one battery. However, I don't see any problems in using a 9-volt battery in a rocket the size of the Strong Arm rocket. Also, since a 9-volt battery uses a clip instead of a spring-load holder it will be less prone to losing contact during high accelerations.

    Enough about batteries. Have you had a chance to fly your flight computer? I'm interested in the results you got. I started working on a similar flight computer based on the SX. However, I gave up on it after the wiring started looking like a rats nest. If I try it again I will have a PC board made, or I'll use the SX48 proto board. There are several features I would like to see in a flight computer:

    - Orientation with the earth's magnetic field
    - Sun orientation
    - Acceleration along the rocket's cental axis
    - GPS
    - Data logging
    - Telemetry transmission
    - Remote radio control for arming and other functions
    - Barometric altimeter
    - Spin detection
    - Video camera control
    - Still camera control
    - Motor gimbal control
    - Anti-spin control
    - Vertical flight control

    Up to this point I've only done still camera control. I hope to add a video camera and implement a remote radio control in the near future.

    Dave
  • johnnyairplanejohnnyairplane Posts: 25
    edited 2007-08-23 07:04
    Sorry Guys, N Cells are NOT 12V batteries!
    HP 41's used them, they're 1.5V

    You're thinking a 23A - it's a 12V cell....

    Yeah, I agree - after doing some research a while back, I found that the cheap 9V's (albertsons, CVS) have
    more storage capacity (maH) than the Cu - tops!

    John
  • m.r.b.m.r.b. Posts: 36
    edited 2007-08-24 11:48
    Following on with the battery pack discussion.....

    Try LiPo mobile (cell) phone battery packs.... They have a stupidly high mAh capacity, are small, are lightweight and compact

    There are variants that are about 4.8V (a reasonable [noparse][[/noparse]low end Vcc] match for 5V logic etc!!), and some that are around 3.6V (a reasonable [noparse][[/noparse]top end Vcc] match for a prop. chip???)

    ... and to top it alll... are easily available. Try your local phone repair stall, at your local open air market .. ·or backstreet 'phone repair shop... They sell ones that are compatable with 'phone handsets... but not a manufactures original part ...·for peanuts!!!

    One word of warning though... make sure you 'balance' the cells properly during discharge.. and especially during charge... They can catch fire or explode!!!

    (I know aero-modellers who use LiPo's... and swear by them... but have told me a horror story or two!!!)

    Regards M.R.B.
  • ghost13ghost13 Posts: 133
    edited 2007-08-31 07:24
    Have either of you flown your flight computers? I'm trying to develop my own with Transolve's BaroMod, but the readings are up to 200 feet different from a commercial altimeter!
  • ScottLawsonScottLawson Posts: 2
    edited 2007-08-31 17:49
    Is 200 feet difference really that much of a difference? if you take two different altimeters from two different companies im betting they wont both report the exact same altitude.· Theres always going to be a slight degree of variation between the readings·
  • David H.David H. Posts: 78
    edited 2007-08-31 20:27
    If you want to use coin type batteries, you could you a holder for (2) 3v 20mmX3.2mm CR2032 Batteries (Digi-Key #BH800S-ND), and put (4) 3v 20mmx1.6mm batteries (Digi-Key #P138-ND). This would be 12V. They are rated at 90MAH.

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    David


    There are 10 types of people in this world,...
    Those that understand binary numbers, and those that don't!!!
  • Mike15Mike15 Posts: 109
    edited 2007-09-01 03:40
    Have either of you flown your flight computers? I'm trying to develop my own with Transolve's BaroMod, but the readings are up to 200 feet different from a commercial altimeter!

    Yes I have flown mine several times now.

    Is 200 feet difference really that much of a difference?

    Depends, If your just data logging no.· If you are using it to deploy a recovery system at a higher altitude not really.· If you are deploying a recovery device at a lower altitude it might.

    If you are using the "flight computer" to control recovery one thing you can do is add an accelrometer. The baro and accel help keep each other in check. The baro is supseptable to false data occuring when the rocket transistions to sonic flight.

    If you have both an accelrometer and baro you can do other things to like air starting other motors.
  • johnnyairplanejohnnyairplane Posts: 25
    edited 2008-01-08 00:28
    Mike15 said...
    The N-cell is a 12 volt battery.

    The 'N' cell is NOT a 12V battery! - I've been using 4 N cells in my HP41CV calculator for over 25 years!

    4 N's = 6 volts....roughly, I put in a metal 'extender' and recharge them in a AA slot in my charger...

    You're thinking the 123 cell.....
  • achilles03achilles03 Posts: 247
    edited 2008-01-10 21:10
    Wow, cool coincidence. I just launched a similar rocket data logger last weekend. Mine wasn't nearly as compact as yours, and took up most of the payload section. It had an accel (+/- 38g) and a pressure sensor. I managed to get a 64kB I2C eeprom working with it, and with a 168Hz sample rate, I got about 97 seconds of data. I don't have a schematic or pictures of it yet, but I did get the flight data into Excel. The first data logger I put in a rocket augured in, and the second is still in a tree in Georgia. So I'm glad this one finally worked!

    www.geocities.com/achilles03/flight_1-6-08.xls

    Dave
  • Shawn LoweShawn Lowe Posts: 635
    edited 2008-01-14 04:11
    Cool project! Very Inspiring! Keep up with the updates!!!

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    Shawn Lowe


    Maybe I should have waited to do that......
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