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Servo Timer II prototype

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  • George
    Hi Guys, We ve been working on the next iteration of the deployment timer we use on our rockets. The idea was to try to simplify the operation of the current
    Message 1 of 22 , Mar 6, 2011
      Hi Guys,
      We've been working on the next iteration of the deployment timer we use on our rockets. The idea was to try to simplify the operation of the current one, and make it smaller and lighter. It is now about half the size and weighs in at 6 grams. The goal is to get to a point where the entire release timer including battery and servo is under 20 grams, and all fits into something the size of a tic-tac box.  

      The timer also has a number of different trigger options depending on people's preferences for detecting launch,burnout etc.

      Here is a preview video of the current prototype. The video shows the operation, configuration, and connectivity to other devices like the uMAD from Whooshtronics for apogee detection, though other sensors or flight computers can also be connected. The video also shows how you can chain the timers together to get multi-servo functionality for say staging and deployment, or drogue/main parachute operation etc.

      Warning: Watching video may cause severe drowsiness. :)
      http://www.youtube.com/watch?v=xYx-oPSQK8c

      After further testing on actual rockets, the plan is to eventually make the design available again for people to build. When the flight testing is complete, I'll be getting a number of the PCB boards made and these should be available as well. Though I don't have a time frame at this stage.

      - George
    • HenningNT
      Very well done! I wasn t drowsy at all after looking at the video. But I must ask, do you drive the servo directly from the microcontroller? -- Henning
      Message 2 of 22 , Mar 6, 2011
        Very well done!

        I wasn't drowsy at all after looking at the video.

        But I must ask, do you drive the servo directly from the microcontroller?

        --
        Henning

        --- In water-rockets@yahoogroups.com, "George" <air.command@...> wrote:
        >
        > Hi Guys,
        > We've been working on the next iteration of the deployment timer we
        > use on our rockets. The idea was to try to simplify the operation of the
        > current one, and make it smaller and lighter. It is now about half the
        > size and weighs in at 6 grams. The goal is to get to a point where the
        > entire release timer including battery and servo is under 20 grams, and
        > all fits into something the size of a tic-tac box.
        >
        > The timer also has a number of different trigger options depending on
        > people's preferences for detecting launch,burnout etc.
        >
        > Here is a preview video of the current prototype. The video shows the
        > operation, configuration, and connectivity to other devices like the
        > uMAD from Whooshtronics
        > <http://www.whooshtronics.com/products-t110/umad.aspx> for apogee
        > detection, though other sensors or flight computers can also be
        > connected. The video also shows how you can chain the timers together to
        > get multi-servo functionality for say staging and deployment, or
        > drogue/main parachute operation etc.
        >
        > Warning: Watching video may cause severe drowsiness. :)
        > http://www.youtube.com/watch?v=xYx-oPSQK8c
        > <http://www.youtube.com/watch?v=xYx-oPSQK8c>
        >
        > After further testing on actual rockets, the plan is to eventually make
        > the design available again for people to build. When the flight testing
        > is complete, I'll be getting a number of the PCB boards made and
        > these should be available as well. Though I don't have a time frame
        > at this stage.
        >
        > - George
        >
      • air.command
        ... microcontroller? ... Hi Henning, The servo power comes from the battery through a voltage regulator located underneath:
        Message 3 of 22 , Mar 7, 2011
          --- In water-rockets@yahoogroups.com, "HenningNT" <henning.torsteinsen@...> wrote:
          >
          > But I must ask, do you drive the servo directly from the microcontroller?
          >
          > --
          > Henning
          >

          Hi Henning,

          The servo power comes from the battery through a voltage regulator located underneath:
          https://lh3.googleusercontent.com/_3qKRAyOVcs8/TW-BLTB2vQI/AAAAAAAABj4/dKt0WF_GDhw/s800/ServoTimerII_01.jpg
          It is rated to 1 Amp. That should be plenty for most servos even while stalled. The microcontroller just provides the digital signal to drive it.  We are going to be using two small 70mA (20c) LiPo batteries to power it. They each weigh about 2 grams. 

          Cheers

          - George
        • HenningNT
          ... I m sorry, I was a bit unclear. I meant the digital signal. -- Henning
          Message 4 of 22 , Mar 7, 2011
            --- In water-rockets@yahoogroups.com, "air.command" <air.command@...> wrote:
            > --- In water-rockets@yahoogroups.com, "HenningNT"
            > <henning.torsteinsen@> wrote:
            > > But I must ask, do you drive the servo directly from the
            > microcontroller?


            > The servo power comes from the battery through a voltage regulator
            > located underneath:
            > https://lh3.googleusercontent.com/_3qKRAyOVcs8/TW-BLTB2vQI/AAAAAAAABj4/d\
            > Kt0WF_GDhw/s800/ServoTimerII_01.jpg
            > <https://lh3.googleusercontent.com/_3qKRAyOVcs8/TW-BLTB2vQI/AAAAAAAABj4/\
            > dKt0WF_GDhw/s800/ServoTimerII_01.jpg>
            > It is rated to 1 Amp. That should be plenty for most servos even while
            > stalled. The microcontroller just provides the digital signal to drive
            > it. We are going to be using two small 70mA (20c) LiPo batteries to
            > power it. They each weigh about 2 grams.

            I'm sorry, I was a bit unclear. I meant the digital signal.

            --
            Henning
          • George
            ... Ahh yes, straight from the microcontroller to the servo control line. - George
            Message 5 of 22 , Mar 7, 2011
              >
              > I'm sorry, I was a bit unclear. I meant the digital signal.
              >
              > --
              > Henning
              >

              Ahh yes, straight from the microcontroller to the servo control line.

              - George
            • vanduuren-t@versanet.de
              Hello George,   I m new to the Wrocket community, Dutchman and living in Germany and allmost 70 years now. The presented timer seems to be the solution for my
              Message 6 of 22 , Mar 7, 2011

                Hello George,

                 

                I'm new to the Wrocket community, Dutchman and living in Germany and allmost 70 years now. The presented timer seems to be the solution for my problems of releasing a parachute. Now I'm trying a magnetic system but is not working all the time as it should be. If your timer is available, is it possible to buy one becouse I'm not able to build electronics. Please help me out.

                 

                Regards,

                 

                Ton van Duuren

                Gronau-Germany 

                 

                George <air.command@...> hat am 7. März 2011 um 04:03 geschrieben:

                > Hi Guys,
                > We've been working on the next iteration of the deployment timer we
                > use on our rockets. The idea was to try to simplify the operation of the
                > current one, and make it smaller and lighter. It is now about half the
                > size and weighs in at 6 grams. The goal is to get to a point where the
                > entire release timer including battery and servo is under 20 grams, and
                > all fits into something the size of a tic-tac box.
                >
                > The timer also has a number of different trigger options depending on
                > people's preferences for detecting launch,burnout etc.
                >
                > Here is a preview video of the current prototype. The video shows the
                > operation, configuration, and connectivity to other devices like the
                > uMAD from Whooshtronics
                > <http://www.whooshtronics.com/products-t110/umad.aspx>  for apogee
                > detection, though other sensors or flight computers can also be
                > connected. The video also shows how you can chain the timers together to
                > get multi-servo functionality for say staging and deployment, or
                > drogue/main parachute operation etc.
                >
                > Warning: Watching video may cause severe drowsiness. :)
                > http://www.youtube.com/watch?v=xYx-oPSQK8c
                > <http://www.youtube.com/watch?v=xYx-oPSQK8c>
                >
                > After further testing on actual rockets, the plan is to eventually make
                > the design available again for people to build. When the flight testing
                > is complete, I'll be getting a number of the PCB boards made and
                > these should be available as well. Though I don't have a time frame
                > at this stage.
                >
                > - George
              • George
                Hi Ton and welcome :), The servo timer still has to go through flight trials to make sure it behaves well on real rockets under real world conditions. We ll be
                Message 7 of 22 , Mar 7, 2011
                  Hi Ton and welcome :),

                  The servo timer still has to go through flight trials to make sure it behaves well on real rockets under real world conditions. We'll be doing those in the coming weeks. If all goes well, I'll be getting a number of PCBs made by a board manufacturer, and then a limited number of assembled boards will be available. I don't know what the final price will be yet since I'm most likely going to get someone else this time to assemble them. I'm happy to send you a notification when they are ready if you like.

                  You will still need to supply your own RC servo motor though. We've been testing the timer with different servos from standard sized ones, down to the micro and sub-micro as well.

                  The timer, however, is only a part of the deployment mechanism of course so parachute ejection mechanism and packing technique are also important. We still crash our rockets sometimes because of parachute tangling, or other mechanical failures with the deployment mechanism.

                  Could you tell us a little more about which kind of magnetic deployment are you using? Do you know which aspect of your system is sometimes failing?

                  - George




                  --- In water-rockets@yahoogroups.com, "vanduuren-t@..." <vanduuren-t@...> wrote:
                  >
                  >
                  > Hello George,
                  >
                  >  
                  >
                  > I'm new to the Wrocket community, Dutchman and living in Germany and allmost 70
                  > years now. The presented timer seems to be the solution for my problems of
                  > releasing a parachute. Now I'm trying a magnetic system but is not working all
                  > the time as it should be. If your timer is available, is it possible to buy one
                  > becouse I'm not able to build electronics. Please help me out.
                  >
                  >  
                  >
                  > Regards,
                  >
                  >  
                  >
                  > Ton van Duuren
                  >
                  > Gronau-Germany 
                  >
                  >
                  >
                  >  
                  >
                  > George <air.command@...> hat am 7. März 2011 um 04:03 geschrieben:
                  >
                  > > Hi Guys,
                  > > We've been working on the next iteration of the deployment timer we
                  > > use on our rockets. The idea was to try to simplify the operation of the
                  > > current one, and make it smaller and lighter. It is now about half the
                  > > size and weighs in at 6 grams. The goal is to get to a point where the
                  > > entire release timer including battery and servo is under 20 grams, and
                  > > all fits into something the size of a tic-tac box.
                  > >
                  > > The timer also has a number of different trigger options depending on
                  > > people's preferences for detecting launch,burnout etc.
                  > >
                  > > Here is a preview video of the current prototype. The video shows the
                  > > operation, configuration, and connectivity to other devices like the
                  > > uMAD from Whooshtronics
                  > > <http://www.whooshtronics.com/products-t110/umad.aspx>  for apogee
                  > > detection, though other sensors or flight computers can also be
                  > > connected. The video also shows how you can chain the timers together to
                  > > get multi-servo functionality for say staging and deployment, or
                  > > drogue/main parachute operation etc.
                  > >
                  > > Warning: Watching video may cause severe drowsiness. :)
                  > > http://www.youtube.com/watch?v=xYx-oPSQK8c
                  > > <http://www.youtube.com/watch?v=xYx-oPSQK8c>
                  > >
                  > > After further testing on actual rockets, the plan is to eventually make
                  > > the design available again for people to build. When the flight testing
                  > > is complete, I'll be getting a number of the PCB boards made and
                  > > these should be available as well. Though I don't have a time frame
                  > > at this stage.
                  > >
                  > > - George
                  >
                • vanduuren-t@versanet.de
                  Hi George, Thanks for your reply to my question (servo-timer II). The magnetic system I m using is a copy, made by Ruben van der Laan. I recommend looking at
                  Message 8 of 22 , Mar 8, 2011

                    Hi George,

                    Thanks for your reply to my question (servo-timer II). The magnetic system I'm using is a copy, made by Ruben van der Laan. I recommend looking at his website to see the details. http://waterrocket.rubenlaan.nl/page7/page7html

                    What I also want to try is the use of an normal altimeter (Perfectflite)which is produced to fire an igniter at apogee and via a small relais for controlling an micro servo. Do you think this could work? I'm not an electronic-man.

                     

                    Regards,

                     

                    Ton van Duuren

                    Gronau-Germany 

                     

                    George <air.command@...> hat am 7. März 2011 um 23:12 geschrieben:

                    > Hi Ton and welcome :),
                    >
                    > The servo timer still has to go through flight trials to make sure it behaves well on real rockets under real world conditions. We'll be doing those in the coming weeks. If all goes well, I'll be getting a number of PCBs made by a board manufacturer, and then a limited number of assembled boards will be available. I don't know what the final price will be yet since I'm most likely going to get someone else this time to assemble them. I'm happy to send you a notification when they are ready if you like.
                    >
                    > You will still need to supply your own RC servo motor though. We've been testing the timer with different servos from standard sized ones, down to the micro and sub-micro as well.
                    >
                    > The timer, however, is only a part of the deployment mechanism of course so parachute ejection mechanism and packing technique are also important. We still crash our rockets sometimes because of parachute tangling, or other mechanical failures with the deployment mechanism.
                    >
                    > Could you tell us a little more about which kind of magnetic deployment are you using? Do you know which aspect of your system is sometimes failing?
                    >
                    > - George
                    >
                    >
                    >
                    >
                    > --- In water-rockets@yahoogroups.com, "vanduuren-t@..." <vanduuren-t@...> wrote:
                    > >
                    > >
                    > > Hello George,
                    > >
                    > >  
                    > >
                    > > I'm new to the Wrocket community, Dutchman and living in Germany and allmost 70
                    > > years now. The presented timer seems to be the solution for my problems of
                    > > releasing a parachute. Now I'm trying a magnetic system but is not working all
                    > > the time as it should be. If your timer is available, is it possible to buy one
                    > > becouse I'm not able to build electronics. Please help me out.
                    > >
                    > >  
                    > >
                    > > Regards,
                    > >
                    > >  
                    > >
                    > > Ton van Duuren
                    > >
                    > > Gronau-Germany 
                    > >
                    > >
                    > >
                    > >  
                    > >
                    > > George <air.command@...> hat am 7. März 2011 um 04:03 geschrieben:
                    > >
                    > > > Hi Guys,
                    > > > We've been working on the next iteration of the deployment timer we
                    > > > use on our rockets. The idea was to try to simplify the operation of the
                    > > > current one, and make it smaller and lighter. It is now about half the
                    > > > size and weighs in at 6 grams. The goal is to get to a point where the
                    > > > entire release timer including battery and servo is under 20 grams, and
                    > > > all fits into something the size of a tic-tac box.
                    > > >
                    > > > The timer also has a number of different trigger options depending on
                    > > > people's preferences for detecting launch,burnout etc.
                    > > >
                    > > > Here is a preview video of the current prototype. The video shows the
                    > > > operation, configuration, and connectivity to other devices like the
                    > > > uMAD from Whooshtronics
                    > > > <http://www.whooshtronics.com/products-t110/umad.aspx>  for apogee
                    > > > detection, though other sensors or flight computers can also be
                    > > > connected. The video also shows how you can chain the timers together to
                    > > > get multi-servo functionality for say staging and deployment, or
                    > > > drogue/main parachute operation etc.
                    > > >
                    > > > Warning: Watching video may cause severe drowsiness. :)
                    > > > http://www.youtube.com/watch?v=xYx-oPSQK8c
                    > > > <http://www.youtube.com/watch?v=xYx-oPSQK8c>
                    > > >
                    > > > After further testing on actual rockets, the plan is to eventually make
                    > > > the design available again for people to build. When the flight testing
                    > > > is complete, I'll be getting a number of the PCB boards made and
                    > > > these should be available as well. Though I don't have a time frame
                    > > > at this stage.
                    > > >
                    > > > - George
                    > >
                    >
                    >
                  • Clifford Heath
                    ... Ton, The magnetic tumbler system, as with any purely-inertial system, does not work and CAN NOT WORK. Its design is based on a fundamental misunderstanding
                    Message 9 of 22 , Mar 8, 2011
                      On 09/03/2011, at 2:48 AM, vanduuren-t@... wrote:
                      > Thanks for your reply to my question (servo-timer II). The magnetic
                      > system I'm using is a copy, made by Ruben van der Laan. I recommend
                      > looking at his website to see the details. http://waterrocket.rubenlaan.nl/page7/page7.html
                      >

                      Ton,

                      The magnetic tumbler system, as with any purely-inertial system, does
                      not work
                      and CAN NOT WORK. Its design is based on a fundamental misunderstanding
                      of what happens at agogee *from the rockets perspective". NOTHING
                      happens.
                      That's right; from inside the rocket, there is no acceleration in any
                      direction that
                      reliably occurs at apogee, so you can't build any kind of inertial
                      system to detect
                      it.

                      Instead, you have to detect something from outside the rocket.
                      Skylight, the earth's
                      magnetic field, atmospheric pressure, and time since launch are all
                      candidates.
                      There are probably others, but an acceleration is not amongst them.

                      Clifford Heath.
                    • Dennis
                      ... The magnetic tumbler system, as with any purely-inertial system, does not work and CAN NOT WORK. Its design is based on a fundamental misunderstanding of
                      Message 10 of 22 , Mar 8, 2011
                        >>>
                        The magnetic tumbler system, as with any purely-inertial system, does not work and CAN NOT WORK. Its design is based on a fundamental misunderstanding of what happens at agogee *from the rockets perspective". NOTHING happens.
                        >>>

                        Clifford and Ton,

                        Respectfully, I don't know if I can agree 100% that a magnetic device cannot work here. If it relies only on inertia, probably not. However, if you use the attraction from one free moving magnet drawn to another mounted magnet, I believe that it may be made to work.

                        Let me try to describe the device that I have tried. It differs from Ruben's design.

                        A special magnet made in the shape of a ball fits closely yet moves freely inside a short PVC tube. Fixed at the upper end of the tube is an ordinary magnet. The length of the tube is just long enough for the magnetic ball to rest at the bottom of the upright tube without jumping up to the fixed magnet. However, if the tube is tilted much off vertical, as at past apogee and nosediving, the magnet no longer is held back enough by gravity and immediately jumps to the other magnet. The force of the magnetic pull where they collide is strong enough to activate a deployment trigger.It will do the same thing in zero gravity or normal gravity. Unfortunately it also jumps because of inertia when the rocket decelerates.

                        I know most of you will realize that the device will work too soon and it indeed does. There needs to be some tension applied inside the tube to slow the movement. But once the attraction starts, it continues as slowly as you can make it until they collide. There is also a possibility of just slowly releasing the tension on the moving magnet beginning at launch. Then whenever the tension is off, as soon as the rocket tilts, it will trigger deployment.

                        The main drawback with the device I made was too much weight versus the small 2 liter test rocket lifting it. The magnets are always heavy. If the device were made lighter and the rocket used had more volume it could work.

                        Dennis
                      • Clifford Heath
                        ... That s because you still don t understand. Enter some normal values into my simulation, and study the acceleration graph very carefully as you read what I
                        Message 11 of 22 , Mar 8, 2011
                          On 09/03/2011, at 5:07 PM, Dennis wrote:
                          > Respectfully, I don't know if I can agree 100% that a magnetic
                          > device cannot work here.
                          >

                          That's because you still don't understand. Enter some normal values
                          into my simulation,
                          and study the acceleration graph very carefully as you read what I
                          write below.

                          > If it relies only on inertia, probably not. However, if you use the
                          > attraction from one free moving magnet drawn to another mounted
                          > magnet, I believe that it may be made to work.
                          >
                          > Let me try to describe the device that I have tried. It differs from
                          > Ruben's design.
                          >
                          > A special magnet made in the shape of a ball fits closely yet moves
                          > freely inside a short PVC tube. Fixed at the upper end of the tube
                          > is an ordinary magnet. The length of the tube is just long enough
                          > for the magnetic ball to rest at the bottom of the upright tube
                          > without jumping up to the fixed magnet. However, if the tube is
                          > tilted much off vertical, as at past apogee and nosediving
                          >

                          There is no "vertical" or "off vertical" when you're travelling
                          freely, as at apogee.
                          Verticality is defined by the pull of gravity, but because the rocket
                          is flying freely
                          under the influence of gravity, nothing *inside* the rocket can detect
                          gravity and
                          hence verticality. That's what free-fall means.

                          > , the magnet no longer is held back enough by gravity and
                          > immediately jumps to the other magnet.
                          >

                          This will happen immediately on burnout, when acceleration drops from
                          some tens of G's upwards to perhaps 6 G's downwards (due to drag).

                          > I know most of you will realize that the device will work too soon
                          > and it indeed does. There needs to be some tension applied inside
                          > the tube to slow the movement.
                          >

                          If you "slow the movement", you've made a timer, triggered by burnout.
                          That
                          could work, but it's not a magnetic nor an inertial apogee detector
                          any more.


                          This attempt has been repeated almost every year for the fifteen years
                          since
                          I started this water rockets list, and no-one has ever been able to
                          make it work.
                          Eventually however, most people come to understand why it cannot work.

                          Clifford Heath.

                          > But once the attraction starts, it continues as slowly as you can
                          > make it until they collide. There is also a possibility of just
                          > slowly releasing the tension on the moving magnet beginning at
                          > launch. Then whenever the tension is off, as soon as the rocket
                          > tilts, it will trigger deployment.
                          >
                          > The main drawback with the device I made was too much weight versus
                          > the small 2 liter test rocket lifting it. The magnets are always
                          > heavy. If the device were made lighter and the rocket used had more
                          > volume it could work.
                          >
                          > Dennis
                          >
                          >
                          >
                        • George
                          It took us a while too to realize how this works when we first started with rockets. It s definitely not an intuitive concept. I ve posted this one before,
                          Message 12 of 22 , Mar 8, 2011
                            It took us a while too to realize how this works when we first started with rockets.  It's definitely not an intuitive concept.

                            I've posted this one before, but I'm just including it since this issue has come up again:

                            In this experiment we filmed what happens to a free floating weight (bead of mercury) on board a rocket during flight. Both flights demonstrate the concept that nothing happens to the weight at apogee.

                            http://www.youtube.com/watch?v=JDWYTphuGCs 

                            Here is the full writeup of the experiment along with explanations
                            http://www.aircommandrockets.com/day85.htm


                            As Clifford mentioned, slowing the rising magnet at a slower rate, in effect creates a timer.  If the free magnet was attached to a spool that could unwind then at burnout the magnet flies up, slowed by the spool, but the force of the other fixed magnet would then continue to unwind the spool until they came together a while later. It wouldn't be detecting apogee though.

                            - George
                          • Dennis
                            There may have been a misunderstanding if this device was thought to be claimed as either an inertial apogee detector or a magnetic apogee detector. As I
                            Message 13 of 22 , Mar 9, 2011
                              There may have been a misunderstanding if this device was thought to be claimed as either an inertial apogee detector or a magnetic apogee detector. As I understand it, a magnetic detector uses electronics that work with the Earth's magnetic field. Nothing about this device does that. It was also acknowledged that it fails miserably as strictly an inertial apogee detector. I mentioned it here because another magnetic device was being considered.

                              My point of bringing up the device was that the two magnets attract each other the same whatever direction the rocket is pointing. Only when at rest in normal gravity on the launcher and during the Gs of acceleration are they kept apart. Otherwise when tumbling in free-fall there doesn't need to be any vertical to work and I'm still betting they will be pulled together.

                              If it hasn't been done in fifteen years I suppose it never will be. Everything has already been achieved here, might as well toss the rocket building junk in the trash and find another hobby to waste time with. Someone should tell the medical research people to give up and stop wasting their donated funds still trying to find the same old cures.
                            • Clifford Heath
                              Dennis, No-one here wants to stifle innovation - far from it, we re here because we re all innovators and want to share that. However, the topic of inertial
                              Message 14 of 22 , Mar 9, 2011
                                Dennis,

                                No-one here wants to stifle innovation - far from it, we're here
                                because we're all innovators and want to share that.

                                However, the topic of inertial apogee detection (which you say
                                you aren't bringing up again) does come up very regularly,
                                and has often devolved into long and pointless discussions,
                                and many of us are keen to avoid that again.

                                > My point of bringing up the device was that the two magnets attract
                                > each other the same whatever direction the rocket is pointing. Only
                                > when at rest in normal gravity on the launcher and during the Gs of
                                > acceleration are they kept apart. Otherwise when tumbling in free-
                                > fall there doesn't need to be any vertical to work and I'm still
                                > betting they will be pulled together.
                                >

                                Of course. You can use that to detect low gravity (or negative
                                acceleration, as during drag). However, that occurs "too soon"
                                for apogee, which you admit in your first email. Your "too soon"
                                comment implied that you had hoped for apogee detection, but
                                realised it doesn't work. Good for you.

                                If you want to detect either launch or burnout, there are many
                                simpler solutions than the one you offer. However, they all need
                                some further mechanism (like a timer) to release a chute at the
                                right time. If a further mechanism can work, perhaps it doesn't
                                need any such trigger?

                                Clifford Heath.
                              • vanduuren-t@versanet.de
                                Hello Clifford,   Ground tests were positiv in 90% of all cases. Could not test in the actual rocket but you could -off cource- be right. The more secure way
                                Message 15 of 22 , Mar 9, 2011

                                  Hello Clifford,

                                   

                                  Ground tests were positiv in 90% of all cases. Could not test in the actual rocket but you could -off cource- be right. The more secure way would be a servo driven system. I'm waiting for George now.

                                   

                                  Ton van Duuren

                                   

                                  Clifford Heath <clifford.heath@...> hat am 8. März 2011 um 22:22 geschrieben:

                                  > On 09/03/2011, at 2:48 AM, vanduuren-t@... wrote:
                                  > > Thanks for your reply to my question (servo-timer II). The magnetic 
                                  > > system I'm using is a copy, made by Ruben van der Laan. I recommend 
                                  > > looking at his website to see the details. http://waterrocket.rubenlaan.nl/page7/page7.html
                                  > >
                                  >
                                  > Ton,
                                  >
                                  > The magnetic tumbler system, as with any purely-inertial system, does 
                                  > not work
                                  > and CAN NOT WORK. Its design is based on a fundamental misunderstanding
                                  > of what happens at agogee *from the rockets perspective". NOTHING 
                                  > happens.
                                  > That's right; from inside the rocket, there is no acceleration in any 
                                  > direction that
                                  > reliably occurs at apogee, so you can't build any kind of inertial 
                                  > system to detect
                                  > it.
                                  >
                                  > Instead, you have to detect something from outside the rocket. 
                                  > Skylight, the earth's
                                  > magnetic field, atmospheric pressure, and time since launch are all 
                                  > candidates.
                                  > There are probably others, but an acceleration is not amongst them.
                                  >
                                  > Clifford Heath.
                                • George
                                  The more secure way would be a servo driven system. I m waiting for George now. ... Hi Ton, Servo driven deployment is only one of many approaches. Have you
                                  Message 16 of 22 , Mar 9, 2011
                                    The more secure way would be a servo driven system. I'm waiting for George now.
                                    >
                                    >  
                                    >
                                    > Ton van Duuren
                                    >
                                    >

                                    Hi Ton,

                                    Servo driven deployment is only one of many approaches. Have you tried a Tomy timer based system? or Dave Johnson's  air-speed flap approach? (http://dogrocket.home.mindspring.com/WaterRockets/chute.html ) Both of these have been used with quite good success rates over the years. Relatively simple and inexpensive to build. If you are keen to get flying as soon as possible, then I'd recommend these before the timer becomes available.

                                    - George
                                  • Bruce
                                    George, I notice you dont mention the optical method. This doesnt detect apogee as such, but when the rocket tips over to do it s descent. I thought it was the
                                    Message 17 of 22 , Mar 10, 2011
                                      George,
                                      I notice you dont mention the optical method. This doesnt detect apogee as such, but when the rocket tips over to do it's descent.
                                      I thought it was the easiest way to go and I've put it in my wrocket. Now, I still havnt had a chance to fly it yet so I cant say whether its any good, but it looks like it might be.

                                      Bruce





                                      --- In water-rockets@yahoogroups.com, "George" <air.command@...> wrote:
                                      >
                                      > The more secure way would be a servo driven system. I'm waiting for
                                      > George now.
                                      > >
                                      > > Â
                                      > >
                                      > > Ton van Duuren
                                      > >
                                      > >
                                      >
                                      > Hi Ton,
                                      >
                                      > Servo driven deployment is only one of many approaches. Have you tried a
                                      > Tomy timer based system? or Dave Johnson's air-speed flap approach?
                                      > (http://dogrocket.home.mindspring.com/WaterRockets/chute.html
                                      > <http://dogrocket.home.mindspring.com/WaterRockets/chute.html> ) Both
                                      > of these have been used with quite good success rates over the years.
                                      > Relatively simple and inexpensive to build. If you are keen to get
                                      > flying as soon as possible, then I'd recommend these before the timer
                                      > becomes available.
                                      >
                                      > - George
                                      >
                                    • George
                                      Hi Bruce, I don t have any experience with the optical systems, though I have seen them built by a number of rocketeers now with mixed results. They seem to
                                      Message 18 of 22 , Mar 10, 2011
                                        Hi Bruce,

                                        I don't have any experience with the optical systems, though I have seen them built by a number of rocketeers now with mixed results. They seem to work well for some, while others have only had partial success. I wonder if putting colour or IR filters in front of them would help give better discrimination between land and sky, rather than just brightness.

                                        - George

                                        --- In water-rockets@yahoogroups.com, "Bruce" <escapehatch@...> wrote:
                                        >
                                        > George,
                                        > I notice you dont mention the optical method. This doesnt detect apogee as such, but when the rocket tips over to do it's descent.
                                        > I thought it was the easiest way to go and I've put it in my wrocket. Now, I still havnt had a chance to fly it yet so I cant say whether its any good, but it looks like it might be.
                                        >
                                        > Bruce
                                        >
                                        >
                                      • George
                                        This is just a quick update on the progress of the timer. We flew 3 different rockets with the timer 7 times this weekend, and all had successful deploys.
                                        Message 19 of 22 , Mar 30, 2011
                                          This is just a quick update on the progress of the timer. We flew 3 different rockets with the timer 7 times this weekend, and all had successful deploys. These were only small rockets launched at relatively low pressures. ~100psi. (We were limited by the size of the park where we flew.) A couple of the flights also used the Magnetic Apogee Detector (uMAD) to trigger the timer at apogee. One thing that came to mind is that a MAD probably would not work if the rocket decided to backglide. On one of the MAD flights the rocket started coming down backwards and probably fell about 20 feet before flipping over. It wasn't until it flipped over that the parachute deployed.<br><br>We are now fitting these to bigger rockets to test the timer at higher and lower acceleration launches. Here is a write up from the launch day including a highlights video: <a href="http://www.aircommandrockets.com/day102.htm">http://www.aircommandrockets.com/day102.htm</a> <br><br>- George<br>
                                        • George
                                          Hi Guys, Well the timers have sure taken their time but they are finally finished. :) It s been a fun project to work on as I have learned a lot about SMDs in
                                          Message 20 of 22 , Jun 28, 2011
                                            Hi Guys,

                                            Well the timers have sure taken their time but they are finally finished. :) It's been a fun project to work on as I have learned a lot about SMDs in the process. We took a little longer because we wanted to do a series of test flights with them to see how well they worked in the real world, and so far we are happy with the results.

                                            The full details and the user manual are available here:

                                            http://www.aircommandrockets.com/servo_timer_V2_0.htm 

                                            Thanks to everyone who helped along the way and made suggestions on how to improve it.

                                            - George
                                          • Mike Passerotti
                                            This is a very nice parachute deployment system. Your design is flexible, functional, light weight and your instructions for use are especially good. I
                                            Message 21 of 22 , Jun 30, 2011
                                              This is a very nice parachute deployment system.  Your design is flexible, functional, light weight and your instructions for use are especially good.  I really like the price.
                                               
                                              You're multiple methods of triggering give end users the ability to experiment with their own systems of apogee detection, launch detection or even ground proximity detection.  That's good science.
                                               
                                              Just when I thought your device had it all, you showed the drone chute/main shute deployment.  That will come in handy for those windy days.
                                               
                                              Thank you for your hard work and bringing this to the water rocket community.
                                               
                                              I so look forward to payday so I can buy one.
                                               
                                              Mike
                                              Cincinnati
                                               

                                              To: water-rockets@yahoogroups.com
                                              From: air.command@...
                                              Date: Tue, 28 Jun 2011 11:56:01 +0000
                                              Subject: [water-rockets] Re: Servo Timer II prototype



                                              Hi Guys,

                                              Well the timers have sure taken their time but they are finally finished. :) It's been a fun project to work on as I have learned a lot about SMDs in the process. We took a little longer because we wanted to do a series of test flights with them to see how well they worked in the real world, and so far we are happy with the results.

                                              The full details and the user manual are available here:

                                              http://www.aircommandrockets.com/servo_timer_V2_0.htm 

                                              Thanks to everyone who helped along the way and made suggestions on how to improve it.

                                              - George


                                            • George
                                              Thanks for the nice words and support Mike :) - George
                                              Message 22 of 22 , Jun 30, 2011
                                                Thanks for the nice words and support Mike :)

                                                - George

                                                --- In water-rockets@yahoogroups.com, Mike Passerotti <mikepasserotti@...> wrote:
                                                >
                                                >
                                                > This is a very nice parachute deployment system. Your design is flexible, functional, light weight and your instructions for use are especially good. I really like the price.
                                                >
                                                > You're multiple methods of triggering give end users the ability to experiment with their own systems of apogee detection, launch detection or even ground proximity detection. That's good science.
                                                >
                                                > Just when I thought your device had it all, you showed the drone chute/main shute deployment. That will come in handy for those windy days.
                                                >
                                                > Thank you for your hard work and bringing this to the water rocket community.
                                                >
                                                > I so look forward to payday so I can buy one.
                                                >
                                                > Mike
                                                > Cincinnati
                                                >
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