Data Sensors for Rocket Use

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bandman444

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Ok now this thread I am sure will very quickly get over my head, but I thought this would be very interesting as I will for sure learn a lot.


I am very intrigued by what I have heard student testing and putting in rockets, namely USLI/SLI payloads.

I really wish I could be a part of a team like that and learn how it all works.

[Rant on/]
:rant:
I have fought with our schools administration about starting a rocketry team, and I have always gotten the, "oh thats nice, find some other teacher to do it." Absolutely no teachers on our campus want to "host" the "Rocketry Team" for a million different reasons. SO after meeting with the principal about the matter, (And another round of "Oh isn't that nice") he mandated the Science Chair to run the club (He didn't have any clubs anyway :p). Obviously he has been no help, even "Skipping Lunch" when our club was supposed to meet.
:rant:
EVERY YEAR (since I started it my freshman year three years ago!!!) WE HAVE DESIGNED and BUILT a working completed pair of rockets.
:rant:
For those well versed in TARC (Or anything in that matter)
:rant:
Step one is design, two is build, three is.... TEST!!! Well guess what, without a advisor to the club, we can not launch. Which means $105 paid to enter the competition and wasted not being able to prove our designs. I finally took our team (as a random group of friends of course, not a club) to ROCSTOCK and let them watch a launch, for the first time ever.
:rant:
[Rant off/]

I want to work by myself on something much more complex than a TARC rocket. I would love to be able to compete in SLI but we have to place in TARC first, not to mention the whole rant section over again. Watching the videos of SLI I can't help but drool over the electronics inside those rockets.




I want to know:

What electronics have been put in those style rockets? (Obviously more than an altimeter or accelerometer.)

Where do you buy, build, design complex electronics bays?




When I find what I'm looking for, I ultimately would like to develop a research project and carry out something with scientific merit.

It sounds above my capabilities, but thats why its called learning, right?
 
Take a look at www.sparkfun.com, or search for Arduino as a starting point. This will take you into the world of embedded computing, and physical environment monitoring/measurement. With the right servos and code, you can modify the environment instead of just reading it.

Remember the Nintendo Powerflex glove? There's a flex sensor in there. Tie it to an A/D converter and get a reading of the amount of flex in your fins during flight.

Lots of fun to be had. Open your imagination; the skies the limit.

Cheers,
- Ken

Ok now this thread I am sure will very quickly get over my head, but I thought this would be very interesting as I will for sure learn a lot.


I am very intrigued by what I have heard student testing and putting in rockets, namely USLI/SLI payloads.

I really wish I could be a part of a team like that and learn how it all works.

[Rant on/]
:rant:
I have fought with our schools administration about starting a rocketry team, and I have always gotten the, "oh thats nice, find some other teacher to do it." Absolutely no teachers on our campus want to "host" the "Rocketry Team" for a million different reasons. SO after meeting with the principal about the matter, (And another round of "Oh isn't that nice") he mandated the Science Chair to run the club (He didn't have any clubs anyway :p). Obviously he has been no help, even "Skipping Lunch" when our club was supposed to meet.
:rant:
EVERY YEAR (since I started it my freshman year three years ago!!!) WE HAVE DESIGNED and BUILT a working completed pair of rockets.
:rant:
For those well versed in TARC (Or anything in that matter)
:rant:
Step one is design, two is build, three is.... TEST!!! Well guess what, without a advisor to the club, we can not launch. Which means $105 paid to enter the competition and wasted not being able to prove our designs. I finally took our team (as a random group of friends of course, not a club) to ROCSTOCK and let them watch a launch, for the first time ever.
:rant:
[Rant off/]

I want to work by myself on something much more complex than a TARC rocket. I would love to be able to compete in SLI but we have to place in TARC first, not to mention the whole rant section over again. Watching the videos of SLI I can't help but drool over the electronics inside those rockets.




I want to know:

What electronics have been put in those style rockets? (Obviously more than an altimeter or accelerometer.)

Where do you buy, build, design complex electronics bays?




When I find what I'm looking for, I ultimately would like to develop a research project and carry out something with scientific merit.

It sounds above my capabilities, but thats why its called learning, right?
 
Do a web search for SLI and USLI and you should find most, if not all, of the team's websites. They have to do a website as a part of the project, and there's lots of information available there.

-Kevin
 
It would be fairly easy to build a rocketsonde, that is, a rocket that measures the weather conditions. Typical measurements are temperature, humidity, and pressure (often referred to as PTU). You could also add a photo cell to measure spin rate. The next question is" record or transmit data back? Each has advantages and problems.
 
...Absolutely no teachers on our campus want to "host" the "Rocketry Team" for a million different reasons. SO after meeting with the principal about the matter, (And another round of "Oh isn't that nice") he mandated the Science Chair to run the club (He didn't have any clubs anyway :p). Obviously he has been no help, even "Skipping Lunch" when our club was supposed to meet.

I absolutely, positively HATE hearing stories like this, Bryce, and I wish I could do something to help you other than offer some advice. But, since I can't...

Get your parents (all of the parents) involved in making a call to the principal, and arranging a meeting with him and the science faculty, including the chair. Let your parents make the case that, if the school and its faculty won't find it in their hearts to help students learn, then perhaps it's time to ask the superintendent and the school board to make some changes. School staff listen to parents - especially when the staff knows that parents are willing to talk with their bosses - not only the superintendent of the schools, but also the elected officials who set policy for the district.

The TARC rules allow schools and OTHER YOUTH ORGANIZATIONS to sponsor teams, including YMCA, 4-H, church groups, etc. The only prohibition is that a rocketry club can't sponsor a TARC team - it has to be an organization that has some other focus. So, if you can't work inside the school - find a group that would sponsor you outside of the school. Again, your parents will be instrumental in getting that organization to open up to you. The key would most likely be to show that you wouldn't be financially dependent upon that organization, and that you'd present them in a very good light.

If all else fails, have your parents start a group, themselves. It could be the "Rockwood Kids Interested in Science" club, or something similar. Again, the only prohibition would be that it's not strictly just a rocketry club.

Unfortunately, unless you go to college somewhere where there's already an established SLI program, you may face similar challenges in getting a program started, there. One of the kids at one of our local universities (University of Texas at Arlington) has faced exactly the same indifference at his campus, and has managed to pull together an independent group that has competed in the Battle of the Rockets for a few years. It can be done - you just have to understand that you're going to be doing all the work.

Oh, and I'd definitely have my parents ask the principal to refund the TARC entry fee because of the lack of cooperation of your sponsor - and would threaten to go to the local press if they chose not to cough up the cash.

Hoe you're still happy with the Astro unit.

Hang in there, Bryce.
 
The challenges in making a useful rocket experiment payload are:

  • Defining the experimental goals and specifying the physical inputs you need to measure.
  • Selecting sensors and interfacing them with the correct gain, offset, and filtering.
  • Chosing a microcontroller platform with sufficient analog inputs, resolution, and speed to handle the data you need.
  • Learning how to program the microcontroller board to log the data and control your experiment.
  • Understanding the bandwidth requirements and sampling rate to capture the information.
  • Post-flight processing of the data to extract the information in a format for analysis and presentation.
  • Building, testing, and integrating a system that has to work under flight conditions.
  • Organizing & managing a team that will be dedicated to making regular progress and completing everything on time, within budget.
Experiments could measure:
  • Characteristic of the rocket structure (strain, flex, vibration, heat);
  • Characteristics of the rocket flight (dynamics, altitude, attitude);
  • External environment (atmosphere, particulate sampling, radiation, solar);
  • Ground observation (mapping, infrared, UV, radar);
  • Internal payload (observing an experiment under high g's or low g's)
  • Deploying an active payload (robotic recovery on ground or in air, homing, or longer datalogging under parachute)
Skills needed:
  • Organizational skills to define tasks, follow a schedule, and integrate lots of details.
  • Presentation skills to communicate with your team, your mentors, and the judges.
  • Math and physics to work through the details behind the sensing, measuring, and analysis.
  • Electronics theory and fabrication to design build quality hardware.
  • Programming (especially "real-time embedded") to develop the software needed to interface to the sensors, control experiments, log data, and communicate with other components or equipment.
  • Analysis tools, such as MATLAB, or at least Excel, to post-process the raw data and extract information to support your results and conclusions.
 
It would be fairly easy to build a rocketsonde, that is, a rocket that measures the weather conditions. Typical measurements are temperature, humidity, and pressure (often referred to as PTU). You could also add a photo cell to measure spin rate. The next question is" record or transmit data back? Each has advantages and problems.
Vaisala made a commercial weather rocketsonde using AT G80 motor. Below are some articles and technical specifications on the commercial rocketsonde and a university research device. Both use standard weather radiosonde receivers.

https://www.vaisala.fi/files/Vaisala_Launches_the_RK91_Rocketsonde.pdf

https://www.hobeco.net/pdf/rk91.pdf

https://www.vaisala.com/Vaisala Doc...ticles/VN174/vn174_This_is_rocket_science.pdf

https://www.vaisala.com/en/Pages/default.aspx

Bob
 
Here are a booster section and payload from a research program. Boosters were made by FSI.
PIC6.jpg

PIC07.jpg
 
Hi,

Unfortunately Vaisala stopped the production of their rocket radio sondes a few years back - I guess there just wasn't sufficient market for them. They sold off their remaining supply of G80 motors (I bought a few as well) and donated the remaining rocket bodies (without payload) to our rocket society.

Regards,
Sampo N.
 
I've got one type of booster, made by FSI. It's got an H60-20 (I believe). The two types of sondes (payloads), made by A.I.R. in Boulder, are essentially the same in function, except that one fits inside the booster (like the Vailasa units), while the other sits on top like a "convential" payload. The two sondes are layed out opposite each other - one has the GPS in the nose, the other in the base. I can post pictures if anyone's interested, or put them up on my Photobucket page. They're in kinda bad shape, having been banged atound for the last 13 years...
 
Hi,

Unfortunately Vaisala stopped the production of their rocket radio sondes a few years back - I guess there just wasn't sufficient market for them. They sold off their remaining supply of G80 motors (I bought a few as well) and donated the remaining rocket bodies (without payload) to our rocket society.

Regards,
Sampo N.
I couldn't find a current listing and I'm not surprised. Weather balloons take the same data on the way up that rockets take on the way down, and while the rocket is good for 1 km, the balloon is good to 30 km. I'm fairly certain that most larger military ships launch weather balloons on a routine basis, so the rocket system is redundant and doesn't provide significantly different information than a weather balloon.

The purpose of my posts of the Vaisala rocket was to show what has been done with model rockets using commercial data sensors and conventional commercial weather receivers. The AT G80 used in the rocket sonde had a longer time delay than the commercial hobby version IIRC.

Bob
 
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When considering sensors, there are two types to take into account: analog and digital. Analog sensors are "old school". They've been used forever. The design chatactoristics are well know. The digital sensors are a bit newer. They have the advantage of outputting data in a digital stream. Examples of this are the Sensirion series - https://www.sensirion.com/ . They are typically pre-calibtated and temperature compensated.

Next comes the data collection method - use a transmitter/receiver pair, or a data logger. With a tx/rx, you can lose the rocket but not lose the data. This is a more complicated/expensive way, but again - it's been done forever and turn-key systems are available. Digital data loggers based on small/cheap microcontrollers are becoming more ubiquitious - but you HAVE to get the logger back or everything's lost. The analog/digital selection also applies to the tx/rx system as well. The original systems were analog. If you want to use analog sensors and digital data tranmission, you'll need a way to convert from analog to digital. A lot of microcontrollers have this built in now.

Sensors and data collection is at least a one semester EE class, and if you go into data reduction as well, probably two. But if folks are interested, we can discuss into whatever degree of detail you'd like. I've done this for a living in a university research setting for a little over 20 years.
 
When considering sensors, there are two types to take into account: analog and digital. Analog sensors are "old school". They've been used forever. The design chatactoristics are well know. The digital sensors are a bit newer. They have the advantage of outputting data in a digital stream. Examples of this are the Sensirion series - https://www.sensirion.com/ . They are typically pre-calibtated and temperature compensated.

Next comes the data collection method - use a transmitter/receiver pair, or a data logger. With a tx/rx, you can lose the rocket but not lose the data. This is a more complicated/expensive way, but again - it's been done forever and turn-key systems are available. Digital data loggers based on small/cheap microcontrollers are becoming more ubiquitious - but you HAVE to get the logger back or everything's lost. The analog/digital selection also applies to the tx/rx system as well. The original systems were analog. If you want to use analog sensors and digital data tranmission, you'll need a way to convert from analog to digital. A lot of microcontrollers have this built in now.

Sensors and data collection is at least a one semester EE class, and if you go into data reduction as well, probably two. But if folks are interested, we can discuss into whatever degree of detail you'd like. I've done this for a living in a university research setting for a little over 20 years.
Digital sensors are the way to go if they meet your sampling needs, however you have to make sure that the response time of the sensor is in line with the requirements of your measurements. It's important to get temperature, chemical and humidity sensors in the air flow to accurately sample the atmosphere, and that they have a rapid response.

For example, if you are trying to profile the dew point as a function of altitude, the sensirion humidity sensors won't cut it. Their 1/e response time is 8 seconds, which means they reach 90 percent of the correct value in 16 seconds, 55 percent of value in 24 seconds and 98% of the value in 32 seconds. If you're looking for 20' resolution (1 second at a descent rate of 20 fps) this sensor is not doing to deliver that.

Ambient light can also change the sensor reading as it can be absorbed by the sensing element, chaning the temperature and giving a false reading. The mems pressure sensor are sensitive to this error.

Bob
 
Yup, Bob, you're correct about the lag time. Rockets are a very special case for environmental monitoring. Vasiala used (I believe) something called a humi-cap for humidity and a very fine bead thermister for temp in radiosondes. I don't remember what they use for drop-sondes. Never saw one of their rocketsondes. I can take pictures of the AIR rocketsonde sensors if anyone is interested. I wish I could find the pictures of all the various types of sondes we had. We even had this cute little "weather station" that hung below a stationary balloon and transmitted data back via radio.
On a side note, I hated the Vaisala radiosondes we used. Don't remember the model number, but there was a punched paper tape that had the calibration data, that had to be run through the data receiver *just right*, before balloon launch. Newer models (drop-sondes) were calibrated via a data cable.
 
Yup, Bob, you're correct about the lag time. Rockets are a very special case for environmental monitoring. Vasiala used (I believe) something called a humi-cap for humidity and a very fine bead thermistor for temp in radiosondes. I don't remember what they use for drop-sondes. Never saw one of their rocketsondes. I can take pictures of the AIR rocketsonde sensors if anyone is interested. I wish I could find the pictures of all the various types of sondes we had. We even had this cute little "weather station" that hung below a stationary balloon and transmitted data back via radio.
On a side note, I hated the Vaisala radiosondes we used. Don't remember the model number, but there was a punched paper tape that had the calibration data, that had to be run through the data receiver *just right*, before balloon launch. Newer models (drop-sondes) were calibrated via a data cable.
Measuring atmospheric parameters is not that easy and is controversial in many instances, for example there has been a debate over whether a humicap or a carbon film resistor is better for measuring humidity.

Carbon film resistors got a bad rap because in the late 60s IIRC, an effort to make them easier to use went wrong. A circular slide rule was developed by the government to aid in the conversion from resistance values to humidity. Unfortunately the slide rule conversion was done incorrectly, and the mistake was not noticed for more than 2 years after the sliderules were distributed. The conversion was obviously in error but the folks who funded the sliderules would not admit that a mistake was made. The carbon resistor was claimed to be inaccurate below a certain temperature, so the humidity data below that temperature was disgarded, and has been for decades, depriving atmospheric modelers of some of the most useful and needed data for their weather prediction programs. :bangbang::y:

Bob
 
Here are a booster section and payload from a research program. Boosters were made by FSI.
PIC6.jpg

PIC07.jpg
To Sooner.Boomer

I am very interested in background information you may be willing to share on the FSI boosters and AIR payloads you posted above. In particular:

- Any other photos of the booster and different payloads
- How the payloads were powered
- Motor retention
- Total weights
- Launch method
- Any spec sheets/tech drawings
- Manufacturer/point of contact info

Thanks,
Stan
 
these days it is rare to find a computer that doesn't have an analog to digital converter...called a sound card :). a few years back one fellow used a pizeo microphone to measure the pressure inside a spudgun(uncalibrated but it did provide an interesting graph). record the data as sound and feed that to the comp via the mic input.
rex
 
To Sooner.Boomer

I am very interested in background information you may be willing to share on the FSI boosters and AIR payloads you posted above. In particular:

- Any other photos of the booster and different payloads
- How the payloads were powered
- Motor retention
- Total weights
- Launch method
- Any spec sheets/tech drawings
- Manufacturer/point of contact info

Thanks,
Stan

Photos to follow...

I still have a payload of each type (GPS in base or nose), I can take more photos if you're interested in something specific.

The payloads are powered by AA batteries or a stack of watch batteries soldered onto the circuit board and activated by a jumper on the circuit board.

The motors are epoxied into the body tubes (phenolic), and pinned with brass pins going into graphite nozzle.

Total weight - don't know, I'll have to weigh them (tomorrow maybe).

Launch method, I was told, was via a tower (see pictures of base) using e-matches powered by a hand-cranked "blaster's box" (see pictures).

No spec sheete/drawings, I don't have pictures of receiver, or even know what data/modulation scheme was used.

See photos for only mfgr info I know. There may be more info on circuit boards, I'll have to look.
 
Info from shipping cases. Oldsters on the forum can tell you more about F.S.I.
Last pic shows battery. More later...
PIC2.jpg

PIC03.jpg

PIC10.jpg
 
Booster (airframe+motor) = 334 grams

nose GPS payload = 126 grams

aft GPS payload = 132 grams

weights are aprox. and do not include the small ejection piston or the tiny (6"?) nylon chute. There is no harness between booster body and payload.
 
This is the payload with the GPS antenna in the nose. The antenna is off the picture to the right, you can see the piece of small solid coax sticking out. The blue jumper is for power; you can see a stack of 5 "watch" batteries that provides power; the temperature sensor is the small dot on the wire loop; the pressure sensor is the brass square. The second picture shows the circuit board rotated slightly.

power1.jpg

power2.jpg

This is the circuit board for the payload with the GPS antenna in the aft of the payload. Again, you can see the batteries and the power jumper, and the temperature bead. The white tape to the right of the battery is the humidity sensor. Last picture shows back of this circuit board and the brass pressure sensor.

power3.jpg

power5.jpg
 

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sooner.boomer - My sincere apologies for not acknowledging your responses and all the time and effort you put into them so long ago. I joined the Forum while on R&R from my deployment to Afghanistan...and then completely forgot about the posting when I departed to return there a day or two later. I'm retired now and going through my earlier work; came across your inputs and wanted to send a note. Again, my sincere apologies and many thanks for going through all the trouble to post in the information and photos.
 
No problem. Glad you could find the pictures interesting. I need to find a way to take good high resolution pictures of all the rockets, then box them away. They're slowly falling apart, even from only occasional handling.
 
I'd be happy to offer suggestions on the photos and storage issues; my "second career" post-retirement has been in museum collections management and we deal with those issues every day.
 
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