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  1. jderimig

    Vent hole question?

    ..
  2. jderimig

    Fin beveling tips to minimize rocket spin

    Beveling is a drag reducing measure, not a spin. However if your bevel is not symmetric it could generate some spin forces. Fin alignment to the axis of the rocket is all you need to do to minimize spin. Since the kit has a slotted airframe there should be no issues there. Don't bevel the...
  3. jderimig

    Altimeter switch style

    ^ Fingertek, support your fellow Canadians.
  4. jderimig

    Schurter switches for flight computers

    Not always, I have personal (me) stories on that one. (the second charge can ignite from the one that fires, ask me how I know). I flew an entire season with a non-functioning backup altimeter that I thought was functioning because all the charges blew.
  5. jderimig

    Schurter switches for flight computers

    The weakest component in the system is the person flipping the switch. (Sorry).
  6. jderimig

    Schurter switches for flight computers

    Its very popular these days that people are flying redundant altimeters from the get-go when they start doing dual-deploy. I used to encourage at my club that novices fly single altimeter alot before going to redundant systems. These would be for modest flights where the trajectory would be...
  7. jderimig

    Electronic Flight Cards?

    What about the igniter leads at the pads? Or the rails? Simplest solution, hand sanitizer before touching you face.
  8. jderimig

    Electronic Flight Cards?

    I am fine with the concept but do an FMEA on both systems and then compare value (to be fair). Also I am open minded, someone point out a sunlight viewable table or smartphone for me, mine certainly do not fit the bill. I can't wait to see the first implementation.
  9. jderimig

    Electronic Flight Cards?

    I am geeky as the next guy, but I think a simple paper form is faster and more reliable than any electronic system that is available at the current time. What problem does an electronic flight card solve? Is this a solution (a neat one) looking for a problem?
  10. jderimig

    SOLD MARSA 4 50g Flight Computer-Price Reduction

    The Marsa4 allows you to set the output latch time up to 256 secs. The LED screen brightness can be set Couple others
  11. jderimig

    SOLD MARSA 4 50g Flight Computer-Price Reduction

    Plus anyone who has dealt with me know that these are virtually guaranteed for life, original owner or not.
  12. jderimig

    Contrail Hybrid - alternatives to Pyrodex Pellets for ignition

    Also if you can get Aerotech reloads, you can use the grains of 24mm propellent, preferable grains with a core but you can always core some if they are c-slot. Run the fill tube through the core and light from the core. Tape the grain to the fill tube about 1/2 inch down from the injector...
  13. jderimig

    Contrail Hybrid - alternatives to Pyrodex Pellets for ignition

    Having flow Contrails for about 10 years now you need something that will just burn through the tube but not to fast (even though Pyrodex are pretty fast). The hole in the middle is not needed to light the hybrid. If you can get the Pyrodex powder I would try just casting the powder with any...
  14. jderimig

    Contrail Hybrid - alternatives to Pyrodex Pellets for ignition

    Are triple-7 or any other brand of muzzle loading pellets available?
  15. jderimig

    SOLD MARSA 4 50g Flight Computer-Price Reduction

    Wow, gray screen version. Very rare. The Marsa4 although being larger, is very robust and fully upgradeable to laterst firmware. It has programable features that the new units (Marsa54L) do not have. Very solid still.
  16. jderimig

    Quectel L70 GPS chipset and LoRa

    The PMTK command manuals are kindof hard to find, its not a MT website and there seems to be different versions floating around. Here is one that describes balloon mode, command Packet Type: 886 PMTK_FR_MODE https://cdn.sparkfun.com/assets/parts/1/2/2/8/0/PMTK_Packet_User_Manual.pdf You...
  17. jderimig

    Quectel L70 GPS chipset and LoRa

    Also how the module integrates the antenna with the chipset will make or break the performance of the unit. Many focus on the chipset but its the antenna which ultimately determines the performance in a rocket. Unfortunately that is where the cheap integrators skimp, badly. Look for a module...
  18. jderimig

    Quectel L70 GPS chipset and LoRa

    The Quectel uses the MediaTek3339 chipset which supports dynamic modes similar to Ublox. Quectel doesn't make the chips they just integrate other maker's chipsets into modules. You do not get balloon mode out of the box, it has to be set with an MTK command. The MT3339 also has some other...
  19. jderimig

    Scientific Validity of the software

    Yes that is the only way to determine height with only an IMU. The other easier method is to use an unlocked GPS to determine apogee and get your position directly.
  20. jderimig

    Scientific Validity of the software

    No, the onboard accelerometer does not measure the rocket's acceleration relative to the earth, it measures the acceleration relative to the rocket. The acceleration due to gravity is not measured by the accelerometer, you have to provide that and assume the direction of the acceleration due to...
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