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LaunchPad AlTImeter Technical Support Forum

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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Blenderite
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Re: LaunchPad AlTImeter Technical Support Forum

Post by Blenderite » Wed Nov 19, 2014 8:05 pm

I got it built and now that it is programmed, the buzzer buzzes constantly after I power it on. I double checked the wiring and soldering and everything is put together correctly.

What would cause this? Anyone else have this problem at first?


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U.S. Water Rockets
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Re: LaunchPad AlTImeter Technical Support Forum

Post by U.S. Water Rockets » Thu Nov 20, 2014 12:03 am

DogLover wrote:I got it built and now that it is programmed, the buzzer buzzes constantly after I power it on. I double checked the wiring and soldering and everything is put together correctly.

What would cause this? Anyone else have this problem at first?
It could be a bad microcontroller chip. Have you tried putting in the spare chip that comes in the box?

Other than that is could be a mistake in the wiring. Make sure that's all good and there are no tiny shorts or solder bridges.

It could be that you downloaded the firmware files for another product, like the ServoChron.

Question: when you say it buzzes, does it make a tone or is it buzzing in a harsh or unusual sound?

You might also try unplugging the servo. If the servo is bad/defective or connected wrong, it could be causing power issues for the main board and causing it to act strange.



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Re: LaunchPad AlTImeter Technical Support Forum

Post by Blenderite » Fri Nov 21, 2014 6:32 pm

Ok I got it working, I think. Now if only there was a way to test it first.


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Re: LaunchPad AlTImeter Technical Support Forum

Post by U.S. Water Rockets » Sat Nov 22, 2014 12:31 pm

DogLover wrote:Ok I got it working, I think. Now if only there was a way to test it first.
Put it into a rocket as if you were ready to launch. Plug all the vent holes with tape with the exception of one hole that you leave open. Then give the open hole a big long kiss. That should be enough to trigger a launch and deploy.

What was the issue you had with the build? Is there something we should clarify in the manual?



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Re: LaunchPad AlTImeter Technical Support Forum

Post by Blenderite » Sat Nov 22, 2014 3:25 pm

U.S. Water Rockets wrote:Put it into a rocket as if you were ready to launch. Plug all the vent holes with tape with the exception of one hole that you leave open. Then give the open hole a big long kiss. That should be enough to trigger a launch and deploy.

What was the issue you had with the build? Is there something we should clarify in the manual?
I gave that a try and it seemed to work, a good sign. I think the problem was due to a short circuit on the Altitude/Pressure Sensor.


-Blenderite

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"Get it right, then go for GREATNESS!"

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Re: LaunchPad AlTImeter Technical Support Forum

Post by U.S. Water Rockets » Mon Nov 24, 2014 9:34 pm

DogLover wrote:
U.S. Water Rockets wrote:Put it into a rocket as if you were ready to launch. Plug all the vent holes with tape with the exception of one hole that you leave open. Then give the open hole a big long kiss. That should be enough to trigger a launch and deploy.

What was the issue you had with the build? Is there something we should clarify in the manual?
I gave that a try and it seemed to work, a good sign. I think the problem was due to a short circuit on the Altitude/Pressure Sensor.
Was the short a manufacturing defect? We bought about 5 or 6 of them for the "development" process as well as for taking nice "build" photos for the manual. We never had a bad one from the maker.



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Re: LaunchPad AlTImeter Technical Support Forum

Post by Blenderite » Tue Dec 02, 2014 8:43 am

No it was a epic fail during soldering.


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Re: LaunchPad AlTImeter Technical Support Forum

Post by U.S. Water Rockets » Tue Dec 02, 2014 2:11 pm

DogLover wrote:No it was a epic fail during soldering.
Thanks for being honest about that;-)

Have you been able to launch it yet? You're really going to love how simple it is to use.



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Static pressure holes

Post by blannoy » Thu Jan 01, 2015 1:00 pm

Hi,

I just tested your Altimeter with servo and radial deploy mechanism in a 3 liter rocket. Unfortunately the parachute deployed a few meters from the ground on its way down.
I guess the peak altitude at around 15-20 meters (50 - 65 feet). The electronics wasn't damaged and it reported an altitude of 134 feet.

I wonder what might have caused the apogee detection failure. If I look at the instructions for the static pressure holes, it might have to do with that. I have 4 3 mm holes spread out evenly around the body (volume of around 1 liter) but also a clear strip (5x5 mm) to put the rubber band through for the servo. The holes are clearly too big? Does the servo have to be in an isolated compartment?

thanks for the altimeter design and instructions.

regards

Bob



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Re: Static pressure holes

Post by U.S. Water Rockets » Thu Jan 01, 2015 10:10 pm

blannoy wrote:Hi,

I just tested your Altimeter with servo and radial deploy mechanism in a 3 liter rocket. Unfortunately the parachute deployed a few meters from the ground on its way down.
I guess the peak altitude at around 15-20 meters (50 - 65 feet). The electronics wasn't damaged and it reported an altitude of 134 feet.

I wonder what might have caused the apogee detection failure. If I look at the instructions for the static pressure holes, it might have to do with that. I have 4 3 mm holes spread out evenly around the body (volume of around 1 liter) but also a clear strip (5x5 mm) to put the rubber band through for the servo. The holes are clearly too big? Does the servo have to be in an isolated compartment?

thanks for the altimeter design and instructions.

regards

Bob

Hi Bob,

If the system reported an apogee, then it detected a launch and detected an apogee. The only time when the system will not report an apogee is if the battery is disconnected while going up. Since you say the altitude reported 134 feet and the parachute did deploy, then the apogee detection was triggered. Your vent holes sound reasonable, so there probably wasn't any issue there.

What you are seeing is just the results of having a very low altitude flight. The altimeter is designed to deploy the parachute after it senses the rocket has stopped going up. Then the rocket starts falling, and the servo moves, but if you watch the servo on a bench test, you can see that they don't move instantly. It can take a second for the servo to swing from the armed position to the deployed position. Then you also have to think that it can take a little time for the rubber band to unwind and the parachute to fall out. Then it takes additional time for the parachute to unfurl and the rocket to decelerate. All this usually happens within a second, but sometimes the parachute can get sucked into the wake of the rocket and it will take a long time to open. Other issues can sometimes cause the parachute to be slow in coming out, even though the apogee was properly detected. Falling from 134 feet if you do the calculations it only gives the parachute system about 2.8 seconds to go from armed to fully deployed. That's not a whole lot of time. If your rocket had gone up another 20 meters, it would have probably have fully saved itself from hitting the ground. Probably the best advice we can offer is to try and increase the altitude of the rocket a bit more, find a really quick acting servo, or use a 6V battery for the power source, which will make the servo swing faster. All those will save a bit of time and make the system open a bit faster.

If you aren't doing it now, it's always useful to take video of the rocket from the ground, and put a cheap camera onboard the rocket. One of those 640x480 "Keychain" cameras can be had for under $10, and these will tell you all sorts of things you never knew. For example, you might have a crash and think something went wrong with apogee detect, so you recover the video and you can hear the sound of the servo moving but the rubber band never comes out. You can then concentrate on figuring out how the rubber band could possibly snag on the servo rather than chasing after a failure in the electronics. You will know the electronics worked and the failure was mechanical.

At any rate, we wish you success in your future launches! Good luck!



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Re: LaunchPad AlTImeter Technical Support Forum

Post by bugwubber » Fri Jan 02, 2015 3:33 pm

So it sounds like rocket kissing is in my future. Better break it to Mrs Bugwubber now so she's prepared!


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Re: LaunchPad AlTImeter Technical Support Forum

Post by U.S. Water Rockets » Sat Jan 03, 2015 1:31 am

bugwubber wrote:So it sounds like rocket kissing is in my future. Better break it to Mrs Bugwubber now so she's prepared!
Does that mean you will also be launching some altimeter flights??? Your launches are always quite entertaining.



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Re: Static pressure holes

Post by blannoy » Sun Jan 04, 2015 3:19 pm

Hi,

I just tested it again with higher pressure to start with. This time it worked every time for the three launches.
It seems that it opens quite a bit before apogee. I assume this is unavoidable. The flights were all very stable and there was barely any wind. Could this be due to the static pressure holes? I could put in a delay on the assumption that the starting pressure is always the same.
The reported altitude is way to high (usually 4 digits starting with 10 of 11, so I assume this to be around 1000 feet). Visually I would estimate the height around 60 to 70 meters but it's hard to guess.

cheers

Bob
U.S. Water Rockets wrote: Hi Bob,

If the system reported an apogee, then it detected a launch and detected an apogee. The only time when the system will not report an apogee is if the battery is disconnected while going up. Since you say the altitude reported 134 feet and the parachute did deploy, then the apogee detection was triggered. Your vent holes sound reasonable, so there probably wasn't any issue there.

What you are seeing is just the results of having a very low altitude flight. The altimeter is designed to deploy the parachute after it senses the rocket has stopped going up. Then the rocket starts falling, and the servo moves, but if you watch the servo on a bench test, you can see that they don't move instantly. It can take a second for the servo to swing from the armed position to the deployed position. Then you also have to think that it can take a little time for the rubber band to unwind and the parachute to fall out. Then it takes additional time for the parachute to unfurl and the rocket to decelerate. All this usually happens within a second, but sometimes the parachute can get sucked into the wake of the rocket and it will take a long time to open. Other issues can sometimes cause the parachute to be slow in coming out, even though the apogee was properly detected. Falling from 134 feet if you do the calculations it only gives the parachute system about 2.8 seconds to go from armed to fully deployed. That's not a whole lot of time. If your rocket had gone up another 20 meters, it would have probably have fully saved itself from hitting the ground. Probably the best advice we can offer is to try and increase the altitude of the rocket a bit more, find a really quick acting servo, or use a 6V battery for the power source, which will make the servo swing faster. All those will save a bit of time and make the system open a bit faster.

If you aren't doing it now, it's always useful to take video of the rocket from the ground, and put a cheap camera onboard the rocket. One of those 640x480 "Keychain" cameras can be had for under $10, and these will tell you all sorts of things you never knew. For example, you might have a crash and think something went wrong with apogee detect, so you recover the video and you can hear the sound of the servo moving but the rubber band never comes out. You can then concentrate on figuring out how the rubber band could possibly snag on the servo rather than chasing after a failure in the electronics. You will know the electronics worked and the failure was mechanical.

At any rate, we wish you success in your future launches! Good luck!



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Re: Static pressure holes

Post by U.S. Water Rockets » Sun Jan 04, 2015 11:32 pm

blannoy wrote:Hi,
I just tested it again with higher pressure to start with. This time it worked every time for the three launches.
It seems that it opens quite a bit before apogee. I assume this is unavoidable. The flights were all very stable and there was barely any wind. Could this be due to the static pressure holes? I could put in a delay on the assumption that the starting pressure is always the same.
The reported altitude is way to high (usually 4 digits starting with 10 of 11, so I assume this to be around 1000 feet). Visually I would estimate the height around 60 to 70 meters but it's hard to guess.
Hi Bob,
Are you positive that the parachute is really deploying before apogee? This is something we have never seen in any testing. We spent a great deal of time working on that part of the code, and if anything it should be biased to being a fraction of a second after apogee, since the altitude is read at regular intervals and so the velocity would have to be zero or negative for a complete interval before the software could detect it. The algorithm is not predictive, because there's very limited memory in these low cost microcontroller boards.

It's possible that the pressure ports may need to be larger due to some unforeseen influence that we never encountered. Just as a guess, perhaps the pressure drops in the part of the rocket where you have the altimeter due to compression of the bottles during launch and the subsequent relaxation of the bottles as the rocket decelerates? This is just a speculation.

Is it possible that from your vantage point on the ground it simply looks to you like the rocket is still going up, but in reality it has stalled at apogee and you are seeing some sort of optical illusion that makes it look at though it is climbing?

The only way to know for sure would be to fly and onboard camera and see if you can hear the servo move before or after the rocket starts coming down.

We've never had one deploy early and we have probably over 100 videos of the altimeter during testing and 100 more videos of the altimeter being used for development of our Radial and Hybrid Deploy techniques. But anything is possible. We just don't know what you could be seeing.



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Re: Static pressure holes

Post by blannoy » Mon Jan 05, 2015 7:26 am

U.S. Water Rockets wrote: Hi Bob,
Are you positive that the parachute is really deploying before apogee? This is something we have never seen in any testing. We spent a great deal of time working on that part of the code, and if anything it should be biased to being a fraction of a second after apogee, since the altitude is read at regular intervals and so the velocity would have to be zero or negative for a complete interval before the software could detect it. The algorithm is not predictive, because there's very limited memory in these low cost microcontroller boards.

It's possible that the pressure ports may need to be larger due to some unforeseen influence that we never encountered. Just as a guess, perhaps the pressure drops in the part of the rocket where you have the altimeter due to compression of the bottles during launch and the subsequent relaxation of the bottles as the rocket decelerates? This is just a speculation.

Is it possible that from your vantage point on the ground it simply looks to you like the rocket is still going up, but in reality it has stalled at apogee and you are seeing some sort of optical illusion that makes it look at though it is climbing?

The only way to know for sure would be to fly and onboard camera and see if you can hear the servo move before or after the rocket starts coming down.

We've never had one deploy early and we have probably over 100 videos of the altimeter during testing and 100 more videos of the altimeter being used for development of our Radial and Hybrid Deploy techniques. But anything is possible. We just don't know what you could be seeing.
Hi,

I'll try to do some more tests. For starters, I'll adapt the electronics compartment to be more sturdy. The bottles I use are quite flexible.
Next launch, I'll try to make a video from a distance with a good view on the flight trajectory. I made video's of 2 launches but I was too close to have a clear view.
Have you thought of the possibility to store all data of a single trajectory that can be dumped through a USB connection?
I found software (http://energia.nu) with which the MSP board can be programmed like Arduino kits and a serial debugging output, but your firmware design is closed (and I have no clue with regard to embedded devices programming ;) ).

I'm also thinking of putting in an old android smartphone of mine with a sensor logger, but this would add 100 grams of payload.

cheers

Bob



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