This the email I sent everyone after I talked to each team member about the procedure, and how we should complete it. (everyone gets their own little part so they can focus more critically on their portion of the procedure.)
> Dear Project Team,
> Thank you for your input. So, here is a portion of Mr. Kibler's post on the
> forums of what we are going to do...
> "I propose that we run the two sensors side by side in closed container with
> ambient air (the air around us) to get a baseline data point. Then we'll put
> them in the sealed vacuum chamber, still side-by side, and measure CO2 on
> the Pasco sensor. We can correlate that with the ASP's CO2 sensor
> millivoltage. We could do that at different pressure altitudes in the vacuum
> chamber (4,000 feet = 100 psi. 8,000 feet =200 psi, 12,000 psi =3,000 feet,
> etc.)"
> Does anyone disagree or is confused by what we are trying to do? It doesn't
> hurt to ask questions. I have already asked multiple questions on things I
> did not understand about this.
> Here is my understanding, maybe in more simple terms, in a way that I think
> will have to be understandable if anyone is having trouble.
> Remember, this is a procedure as I think of it to make a Parallax CO2 sensor
> read out ppm.
> **IDEA** What if we would show the procedure to Parallax for their CO2
> sensor page and they accepted it!?! Would this count as all of us having
> something PUBLISHED on the understanding of a CO2 sensor?!? That would
> really help on college applications or job applications!
> We will run the PASCO and the CO2 sensor side by side some where out in the
> open. Lets say we get 380ppm from the PASCO. And we get somewhere around
> 2500 mV from the CO2. Now we know that at 380ppm the sensor outputs 2500 mV.
> This will give as a data point we can reference to. Now we do that, but with
> both of them in the vacuum chamber. Now lets say at 6,000 feet we got a
> reading from the PASCO stating that the ppm concentration was 360 ppm. Also
> that the output from the CO2 sensor was 2200 mV. That will give as
> another data point we can reference to. We keep doing this at different
> altitudes until we have several data points. We then compare those on a
> graph or datasheet to find the constant and multiply the mV outputted by the
> CO2 sensor.
> I have some questions myself on the procedure already!
> 1.) I am unclear when it says, "I propose that we run the two sensors side
> by side in closed container with ambient air (the air around us) to get a
> baseline data point.". Does this mean that we test it in a place that has no
> CO2? Because that is what I am thinking when he said, "baseline data point".
> 2.) When we got to the point described, "We then compare those on a graph or
> datasheet to find the constant and multiply the mV outputted by the CO2
> sensor.", do we include this on the procedure? This would cause us to
> propose an unfinished procedure. Or do we just create a procedure that just
> is on how to collect the CO2 data points?
Here's the procedure you proposed above. Parts of it are solid, but if you carefully examine the garphs we posted from the trials in vacuum chamber you'll see why other parts might not work. Here's where we have to think critically and come up with a solution.
You suggested that we:
1) Run the PASCO and the CO2 sensor side by side some where out in the open.
Good start but the readings will probably go up and down. I suggest that we get this "baseline" data raeding, and all readings, from a closed container so the readings don't go up and down.
2) Lets say we get 380ppm from the PASCO.. and 2500 mV from the CO2. Now we know that at 380ppm the sensor outputs 2500 mV. This will give us a data point we can reference .
I think this is a valid conclusion. Dr. Allen and Sylvie, do you agree?
3) Now we do that... with both of them in the vacuum chamber. Let's say at 6,000 feet [150 psi in the vacuum chamber] we got a reading from the PASCO... of 360 ppm... and the CO2 sensor reads 2200 mV. That will give as another data point we can reference [so we can interpolate or extrapolate.]
PROBLEM: The CO2 millivoltage DID NOT seem to change at all in the vacuum chamber. Just look at the graph lines for CO2 mV from the vacuum chamber trials. I seem to recall that Dr. Allen said "maybe the CO2 sensor ONLY responds to CO2 and not to altitude." Maybe CO2 "partial pressure" doesn't factor in; maybe it does. I don't have the answer to this and it''s our biggest problem and concern.
Sylvie and Dr. Allen, what do you think?
4) We keep doing this at different altitudes until we have several data points. We then compare those on a graph or datasheet to find the constant and multiply the mV outputted by the CO2 sensor.
Conceptually I agree with you Dylan, that this is what we should do. But we have to find a solution to #3 (above) because if the CO2 sensor doesn't respond to 6,000 pressure altitude feet in the vacuum chamber, it probably won't respond at any pressure altitude in the vacuum chamber. We can test it and see (I have; look at the graph lines) and so we need another possible solution.
Other explanations: Maybe it did the trial inproperly. Maybe the sensor was bad, or maybe...? :idea:
So yes, we need to a procedure, soultion, answer, and a constant. I'm eager to hear back from everyone.
Hi, I've been away for a few days. Checking in here quickly.
I suggest that you do a calibration point at a higher level of CO2 concentration. You can do that in a closed chamber like your bell jar or even in a cardboard box sealed up with tape. But instead of a vacuum, increase the CO2 concentration by putting in a small piece of dry ice (as you suggested a couple of posts back), or make an arrangement to breath in and out of the chamber several times to build up the CO2 level significantly. You know both sensors will respond. If you want to do that right, you should have a small computer fan inside the closed container in order to mix and circulate the gas. For refinements, allow for a small leak or bag on the side so that the pressure does not increase or decrease too much and the measurement is always done at atmospheric pressure. And if you do this with breath, it would be best if you can breath in through a dessicant to dry the air. But we already see (from the data sheet) that the MG811 does not respond much to humidity, so drying is secondary.
Testing in the vacuum chamber does reduce the partial pressure, and I do think it would be interesting to do the experiment to compare the MG811 with the Pasco under the 6000ft conditions. The Pasco works on the NDIR principle, so it might respond, but I am not sure about that either. Do you have the specifications for the Pasco? What does it say about the range of CO2 it will measure? Is that in units of ppm or partial pressure?
The reason I suggest testing at higher CO2 concentrations is because those are the levels that are presented on the MG811 data sheet. That is where it is tested by the manufacturer and is supposed to work. I can't emphasize enough the dangers of extrapolation when it comes to sensors. It may be that the MG811 hits a hard limit at around 400ppm and will not respond below that, and what you see during the flight may be a flat line. Maybe, maybe not. But whatever it is, you have learned a lot in the process about the tools and process of measurement.
By the way, when the ASP-2 is in the rocket body, I am picturing it in kind of a closed chamber within the rocket. How does ambient air enter so that it can measure humidity, CO2 and also respond quickly to temperature changes?
By the way, when the ASP-2 is in the rocket body, I am picturing it in kind of a closed chamber within the rocket. How does ambient air enter so that it can measure humidity, CO2 and also respond quickly to temperature changes?
The Student Launch Initiative team that did something similar 8 or 10 years ago built a duct system out of PVC pipe that collected air from outside the rocket, slowed it down, and moved it past the sensors. The mentors were probably more proud of that part of the project than of the electronics, for reasons that escape me.
It is, I think, far too late for the ARLISS group to put together something like that. However, the ASP-2 has (or should have, at least) vents to the outside air already, because the MAWD won't work without them (it's barometric). It is possible that those vents will not be enough to mix the air in the way that Dr. Allen suggested in the test above, and that will affect the CO2 ratings (I assume that air pressure, which is what the MAWD works with settles in much more quickly and easily than does composition of the air).
My assumption is that there will be enough mixing through the MAWD vent holds that the readings are reasonably accurate, if, of course, everything else is working properly.
By the way, when the ASP-2 is in the rocket body, I am picturing it in kind of a closed chamber within the rocket. How does ambient air enter so that it can measure humidity, CO2 and also respond quickly to temperature changes?
Tracy,
I'll hold off on explaining how the ASP goes in, and comes out of the rocket in hopes that one of The Rocketeers will explain it for me...! If not then I'll describe it later. It's simple.It's elegant! It's a work of art!
Rocketeers, who will be the first to answer Dr. Allen...?
I can not find any specifications on the PASCO device. I looked on their website but it seems that the sensor isn't listed anymore. Mr. Kibler, do you have the box and/or manual?
From our past conversations I believe that the sensor does already read out ppm.
I do like the idea of having the dry ice in the vacuum chamber, but it is true, we will need maybe a small fan, (one of those hand held ones?), with something like a small opening in the bell jar. Could we maybe just hang it off the side of the vacuum chamber's base. But that would mean that we could not increase the altitude. But since the CO2 sensor doesn't respond to altitude, that would be fine. Right?
Uh, I do not understand your question. Are you asking me why we would need one, or if we could use one?
Yes, the Pasco measures CO2 in ppm. I also have another sensor on the way for the Vernier Lab Quest module. Same idea as the Pasco, just a different company.
I think Dr. Allen is suggesting that we put a battery-powered fan inside the bell jar with the dry ice so we can seal it off completely and spread the CO2 out evenly.
We could also put the dry ice above the ASP inside the bell jar. Since CO2 gas is more dense than O2 (oxygen) it would "sink."
CO2 conc. with dry ice inside bell jar = 100% concentration (? ppm, ? mV)
CO2 conc. inside jar filled with helium = 0% concentration (? ppm, ? mV)
Ambient CO2 appears to be = 400 ppm, 2200 mV.
Other data points are on the CO2 sensor graph we've used since last June.
Find the values for (? ppm, ? mV) and then calculate the constant.
Uh, I do not understand your question. Are you asking me why we would need one, or if we could use one?
Could you explain to our audience how the ASP goes into, and more importantly how it comes out of the rocket...? How does the "air" get to the CO2 sensor? Some folks seem to be under the impression that the ASP stays in a container inside the rocket as it ascends and descends? Is that correct...?
This is something you might want to consider including in the presentation you have to make on Friday morning after you launch.
Each section you see above is made out of wood, (but fit together so it makes a H shape together).
The two, "|" parts on each side are pieces are circle pieces cut out of wood that are currently facing each other, face to face. The, "-" part in the middle is also cut out from wood, Bit take the shade of a dash.
Like this if it makes any sense.
(the electronics are completely mounted in the open air, directly attached to the wood.)
(Looking from a angle, (straight on it would make the, "H" shape.
This will slide down PERFECTLY into the rocket tubing attached to the shock cord. I have to go and wont be able to expand on my ideas anymore at the time. If there is anything I have missed please expand on my post Mr. Kilber.
I had to delete the picture I made for the ASP because the format in the forum messed it up if you know what I mean.
The ASP is deployed from the rocket at apogee (the highest point in the flight.) It descends on a large parachute and *the sides of the ASP are open.* This allows atmospheric gases to come in contact with the CO2 sensor. This prevents the rocket's exhaust gases (which may contain CO2) from contaminating the sensor/samples since the rocket descends on a separate parachute.
*See attached picture* and say "Cheese" :smilewinkgrin:
The ASP is deployed from the rocket at apogee (the highest point in the flight.) It descends on a large parachute and *the sides of the ASP are open.*
Oh, I forgot all about that, but I did know it last year. That's right. That'll work fine, assuming it's the measurements on the way down that matter to you.
=======================
Our big public launch is this weekend, and the weather is supposed to be perfect. I'm planning to fly my GPS transmitter again, and perhaps fly a 3" dual deployment rocket, going a little higher than I'm used to going. Then it's range duty. I'll be pushing the button for some very interesting rockets this weekend. I can't wait.
A couple of times a year we see someone's rocket separate into two pieces, and either the flyer is slapping himself on the head because he realizes he forgot to connect a quick link, or later in the postmortem we find that it wasn't connected. When I mentor a certification flight I do always double check that part.
A couple of times a year we see someone's rocket separate into two pieces, and either the flyer is slapping himself on the head because he realizes he forgot to connect a quick link, or later in the postmortem we find that it wasn't connected. When I mentor a certification flight I do always double check that part.
Sylvie,
Four or five years ago, and just when they had the weight and parachite size of their TARC rocket dialed in to perfection, another group of Rocketeers made a qualification flight but they forgot to check the quick link. It wasn't closed and they demolished a well-crafted aerospace vehicle. Ouch! They learned a quick lesson about quick links, but more importantly they learned that it''s very important to write and follow a pre-flight checklist. Rocketeers, do we have one for Nevada...?
===============================
I'm in DC and we're dropping Chrisopher off at George Washington University which is just blocks from the big Palin-Glen Back rally on the Washington Mall. I hope we can get in and out of campus smoothly because it's a loooooooong ride back to NH tonight.
What motor are you flying on this weekend: a 29, 38 or 54 mm? Have you set a target altitude? Is your rocket scratch-built? Doual deployment is always the safe and sane idea on an expen$ive rocket. I'm eager to hear how your transmitter works! Keep me posted!
I'll fly a couple of 38mm motors. I have a couple of Cesaroni 38mm four-grain I motors, and I think one of their five-grain J motors, and also several Aerotech 38mm I motors and one AT J500 Green. I'll have my 3" dual deployment rocket (I just built the altimeter bay yesterday), as well as my old standby 4" one, which will fly with the GPS transmitter on board. The 3" rocket will carry a regular (non-GPS) 433 MHz radio beacon, which reminds me I need to bring my receiver.
I'll also make my fourth attempt to ignite an ancient 29mm F40-7 - I've sanded the surfaces, painted the grains with pyrogen, and scraped up the face of the delay grain. I'm not that confident that it'll go, though.
What batteries need to charged? When should voltage be checked? Who checks it? Where is that information recorded? How much voltage is needed to power each electronic device? What gets loaded into the rocket 1st, 2nd, 3rd, etc? When is the ASP-s 2turned on (remember that it needs to be "pre-heated" or warmed up before flight)? Will you check everything to make sure it's opertional before you load it? How is the parachute loaded? When, and by whom? What's the post-flight power-down sequence (after the ASP lands)? We don't want to lose data! What frequencies will the shortwave transmitters be on? How do you set them? How much battery power do they require before they shut off? Who will operate the SW receivers?
Sean and Andrew, you were at ARLISS last year. Please step in and lead us through this. Thanks!
Sorry I havent been on the forum lately, I had been checking it and it was stuck on page 40 and about an hour ago I looked at it again and BOOM! There were another 2 whole pages of posts dated back to August 20th. So then I had to do much catching up.
We need to charge every single battery (remote car battery, GPS battery, "walkie talkie" batteries, the other ones I know I am forgetting). Last year I believe we checked the battery voltage right before we launched. I think last year we loaded the ASP in first, followed by the main parachute, and then our parachute bag (are we going to use one of those again this year Mr.Kibler?). Seeing how we need to preheat the ASP-2 before we launch we should turn it on while we test voltage and correct me if I am wrong, but it takes a good 30-40 minutes to put everything in the rocket, get the rocket out to the launch pad, get the rocket all ready to launch, then actually launching it. I think it will be a good idea to check to make sure everything is operational before we launch. I believe that the parachute is one of the last things that get loaded, Andrew and I know how to fold them so we can do that together.
Are the short wave transmitters the "walkie talkies" we used last year? Last year we were in "teams". Andrew and I were together with someone in their trailer (I forget his name) and we were reading off the altitude to you.
You're right on track. Yes, we need to replace any old batteries with new ones and charge any of the batteries that are rechargeable. These include:
1) The large orange nickel-cadmium (Ni-Cd) battery on the ASP platform (*this powers the BOE and the MAWD.)
2) The battery on the orange rectangular Garmin transmitter, and
3) The battery in the handheld shortwave receiver. This reads out the ASP's location in longitude and latitude.
I think all the other batteries and replaceable; and so they should be replaced. These include:
4) The small back-up Alt-Acc altimeter (AA battery)
5) The rectangular 9-V lithium battery mounted on the ASP platform (*what does it go to)
6) All the batteries in the various handheld receivers and "walkie-talkies" we'll use to communicate:
A) The Garmin Astro 220 The Yaesu VR-500 shortwave receiver
C) The Yaesu VX-8R transmitter-receiver (rechargeable)
D) The "walkie-talkies"
7) What else...?
You mentioned working in teams. Who will work with whom? We have five students, two parents, and me (I'll bet you forgot about me and the parents; can you use us on some mission tasks?) Use your skills and resources (people and materials) strategically and to our best advantage. Don't put someone on a launch-critical task(s) if they're not sure what they're doing. It's critical that everyone in each two-person team know exactly what they're responsible for, how to do it, and how to solve any problems they encounter. So Andrew, Sean, and Dylan: who will be paired with whom, and what will each team be doing...?
Sean, I'm glad your remembered that we used a parachute deployment bag last year; did we use one on BOTH flights...? Where is the one from the first flight? What tasks are you most confident doing? You'll probably be paired with one of the new team members so you can lead and teach. Again, good work! I'm eager to hear back from Andrew and the rest of the team.
What do you know about the "Bloom box" fuel cell? It sounds like it works something like the CO2 sensor, converting O2 into E instead of using CO2 NASICON. Do you think there's NASICON in the Bloom box? Couldn't we do the same thing while using CO2 instead of O2... hmmmmm.... (patent pending - ARLISS Team New Hampshire.) Maybe a new funding source for our projects! Maybe we should talk to a Silicon Valley venture capitalist. I think the Roceketeers missed the significance when you told them about NASICON as an excellent topic to be researching now.
Bloom box: "...each "power plant-in-a-box"... is full of thin fuel cells, bundled and packaged into an outdoor-safe case. The individual cells soak up oxygen on one side, "and fuel on the other [NASICON]?. The two combine within the cell to create a chemical reaction that produces electricity... There's no need for burning or combustion" but it still requires some form of fuel to work. What kind is up to the owner.
"Our system can use fossil fuels like natural gas. Our system can use renewable fuels like landfill gas, bio-gas," Sridhar says. "We can use solar."
I think writing the procedure for the conversion of mV into CO2 is the first thing we need to do right now. We have five team members so we should brake it up into five parts, one for each of us.
***Mr. Kibler***
I understand what is beginning the procedure, (us turning the sensors on and all of that), but what are we ending with? Are we going all the way to the point of where we multiply the mV to get ppm? Or are we just covering to the point where you have all of the data needed to find the constant, but not actually what to do after that? I think we really have to get started on this because everyone is in school for most of the day's time and the amount of homework is really building up. Also since we will have to make up work for high school before we get to go on the trip for the missed days.
Your right. We really need to get working on this procedure since time is very limited because of school. Regarding the work for the missed days of school, I think we need to ask all of our teachers for any work that will be handed out and due that week so we can bring it to Nevada and use some of our free time on it.
"...I think we need to ask all of our teachers for any work that will be handed out and due that week so we can bring it to Nevada and use some of our free time on it.
Justin
Justin,
I'm glad to see that you're thinking and planning ahead. That's part of the learning from this project.
Yes, you will want to let your teachers know that you'll be gone September 14-18, ask for your homework ahead of time, and then bring it with you to Nevada. I've already spoken with the Principal and he'll be looking for a letter from each of you, from me. We'll have homework time set aside each evening at the hotel in Nevada (better remind Mike, Sean, and Dylan. I think Andrew is all set. He planned ahead...)
Comments
Dylan and Rockteers,
Please see my reply to your e-mail and please move the conversation to the forum so that Sylvie and Dr. Allen can see it and guide you along.
Thanks!
Mr. Kibler
> Dear Project Team,
> Thank you for your input. So, here is a portion of Mr. Kibler's post on the
> forums of what we are going to do...
> "I propose that we run the two sensors side by side in closed container with
> ambient air (the air around us) to get a baseline data point. Then we'll put
> them in the sealed vacuum chamber, still side-by side, and measure CO2 on
> the Pasco sensor. We can correlate that with the ASP's CO2 sensor
> millivoltage. We could do that at different pressure altitudes in the vacuum
> chamber (4,000 feet = 100 psi. 8,000 feet =200 psi, 12,000 psi =3,000 feet,
> etc.)"
> Does anyone disagree or is confused by what we are trying to do? It doesn't
> hurt to ask questions. I have already asked multiple questions on things I
> did not understand about this.
> Here is my understanding, maybe in more simple terms, in a way that I think
> will have to be understandable if anyone is having trouble.
> Remember, this is a procedure as I think of it to make a Parallax CO2 sensor
> read out ppm.
> **IDEA** What if we would show the procedure to Parallax for their CO2
> sensor page and they accepted it!?! Would this count as all of us having
> something PUBLISHED on the understanding of a CO2 sensor?!? That would
> really help on college applications or job applications!
> We will run the PASCO and the CO2 sensor side by side some where out in the
> open. Lets say we get 380ppm from the PASCO. And we get somewhere around
> 2500 mV from the CO2. Now we know that at 380ppm the sensor outputs 2500 mV.
> This will give as a data point we can reference to. Now we do that, but with
> both of them in the vacuum chamber. Now lets say at 6,000 feet we got a
> reading from the PASCO stating that the ppm concentration was 360 ppm. Also
> that the output from the CO2 sensor was 2200 mV. That will give as
> another data point we can reference to. We keep doing this at different
> altitudes until we have several data points. We then compare those on a
> graph or datasheet to find the constant and multiply the mV outputted by the
> CO2 sensor.
> I have some questions myself on the procedure already!
> 1.) I am unclear when it says, "I propose that we run the two sensors side
> by side in closed container with ambient air (the air around us) to get a
> baseline data point.". Does this mean that we test it in a place that has no
> CO2? Because that is what I am thinking when he said, "baseline data point".
> 2.) When we got to the point described, "We then compare those on a graph or
> datasheet to find the constant and multiply the mV outputted by the CO2
> sensor.", do we include this on the procedure? This would cause us to
> propose an unfinished procedure. Or do we just create a procedure that just
> is on how to collect the CO2 data points?
> Thank you for your input,
> Dylan Landry
Here's the procedure you proposed above. Parts of it are solid, but if you carefully examine the garphs we posted from the trials in vacuum chamber you'll see why other parts might not work. Here's where we have to think critically and come up with a solution.
You suggested that we:
1) Run the PASCO and the CO2 sensor side by side some where out in the open.
Good start but the readings will probably go up and down. I suggest that we get this "baseline" data raeding, and all readings, from a closed container so the readings don't go up and down.
2) Lets say we get 380ppm from the PASCO.. and 2500 mV from the CO2. Now we know that at 380ppm the sensor outputs 2500 mV. This will give us a data point we can reference .
I think this is a valid conclusion. Dr. Allen and Sylvie, do you agree?
3) Now we do that... with both of them in the vacuum chamber. Let's say at 6,000 feet [150 psi in the vacuum chamber] we got a reading from the PASCO... of 360 ppm... and the CO2 sensor reads 2200 mV. That will give as another data point we can reference [so we can interpolate or extrapolate.]
PROBLEM: The CO2 millivoltage DID NOT seem to change at all in the vacuum chamber. Just look at the graph lines for CO2 mV from the vacuum chamber trials. I seem to recall that Dr. Allen said "maybe the CO2 sensor ONLY responds to CO2 and not to altitude." Maybe CO2 "partial pressure" doesn't factor in; maybe it does. I don't have the answer to this and it''s our biggest problem and concern.
Sylvie and Dr. Allen, what do you think?
4) We keep doing this at different altitudes until we have several data points. We then compare those on a graph or datasheet to find the constant and multiply the mV outputted by the CO2 sensor.
Conceptually I agree with you Dylan, that this is what we should do. But we have to find a solution to #3 (above) because if the CO2 sensor doesn't respond to 6,000 pressure altitude feet in the vacuum chamber, it probably won't respond at any pressure altitude in the vacuum chamber. We can test it and see (I have; look at the graph lines) and so we need another possible solution.
Other explanations: Maybe it did the trial inproperly. Maybe the sensor was bad, or maybe...?
So yes, we need to a procedure, soultion, answer, and a constant. I'm eager to hear back from everyone.
From the lunchroom :smhair: ,
Mr. Kibler
I suggest that you do a calibration point at a higher level of CO2 concentration. You can do that in a closed chamber like your bell jar or even in a cardboard box sealed up with tape. But instead of a vacuum, increase the CO2 concentration by putting in a small piece of dry ice (as you suggested a couple of posts back), or make an arrangement to breath in and out of the chamber several times to build up the CO2 level significantly. You know both sensors will respond. If you want to do that right, you should have a small computer fan inside the closed container in order to mix and circulate the gas. For refinements, allow for a small leak or bag on the side so that the pressure does not increase or decrease too much and the measurement is always done at atmospheric pressure. And if you do this with breath, it would be best if you can breath in through a dessicant to dry the air. But we already see (from the data sheet) that the MG811 does not respond much to humidity, so drying is secondary.
Testing in the vacuum chamber does reduce the partial pressure, and I do think it would be interesting to do the experiment to compare the MG811 with the Pasco under the 6000ft conditions. The Pasco works on the NDIR principle, so it might respond, but I am not sure about that either. Do you have the specifications for the Pasco? What does it say about the range of CO2 it will measure? Is that in units of ppm or partial pressure?
The reason I suggest testing at higher CO2 concentrations is because those are the levels that are presented on the MG811 data sheet. That is where it is tested by the manufacturer and is supposed to work. I can't emphasize enough the dangers of extrapolation when it comes to sensors. It may be that the MG811 hits a hard limit at around 400ppm and will not respond below that, and what you see during the flight may be a flat line. Maybe, maybe not. But whatever it is, you have learned a lot in the process about the tools and process of measurement.
The Student Launch Initiative team that did something similar 8 or 10 years ago built a duct system out of PVC pipe that collected air from outside the rocket, slowed it down, and moved it past the sensors. The mentors were probably more proud of that part of the project than of the electronics, for reasons that escape me.
It is, I think, far too late for the ARLISS group to put together something like that. However, the ASP-2 has (or should have, at least) vents to the outside air already, because the MAWD won't work without them (it's barometric). It is possible that those vents will not be enough to mix the air in the way that Dr. Allen suggested in the test above, and that will affect the CO2 ratings (I assume that air pressure, which is what the MAWD works with settles in much more quickly and easily than does composition of the air).
My assumption is that there will be enough mixing through the MAWD vent holds that the readings are reasonably accurate, if, of course, everything else is working properly.
Tracy,
I'll hold off on explaining how the ASP goes in, and comes out of the rocket in hopes that one of The Rocketeers will explain it for me...! If not then I'll describe it later. It's simple. It's elegant! It's a work of art!
Rocketeers, who will be the first to answer Dr. Allen...?
Mark
From our past conversations I believe that the sensor does already read out ppm.
I do like the idea of having the dry ice in the vacuum chamber, but it is true, we will need maybe a small fan, (one of those hand held ones?), with something like a small opening in the bell jar. Could we maybe just hang it off the side of the vacuum chamber's base. But that would mean that we could not increase the altitude. But since the CO2 sensor doesn't respond to altitude, that would be fine. Right?
Yes, the Pasco measures CO2 in ppm. I also have another sensor on the way for the Vernier Lab Quest module. Same idea as the Pasco, just a different company.
I think Dr. Allen is suggesting that we put a battery-powered fan inside the bell jar with the dry ice so we can seal it off completely and spread the CO2 out evenly.
We could also put the dry ice above the ASP inside the bell jar. Since CO2 gas is more dense than O2 (oxygen) it would "sink."
CO2 conc. with dry ice inside bell jar = 100% concentration (? ppm, ? mV)
CO2 conc. inside jar filled with helium = 0% concentration (? ppm, ? mV)
Ambient CO2 appears to be = 400 ppm, 2200 mV.
Other data points are on the CO2 sensor graph we've used since last June.
Find the values for (? ppm, ? mV) and then calculate the constant.
Hmmm... where to go from here?
Homemade pizza awaits (with home-grown tomatoes!)
Mr. Kibler
Could you explain to our audience how the ASP goes into, and more importantly how it comes out of the rocket...? How does the "air" get to the CO2 sensor? Some folks seem to be under the impression that the ASP stays in a container inside the rocket as it ascends and descends? Is that correct...?
This is something you might want to consider including in the presentation you have to make on Friday morning after you launch.
Mr. Kibler
Now brake it up into three sections..
| - |
Each section you see above is made out of wood, (but fit together so it makes a H shape together).
The two, "|" parts on each side are pieces are circle pieces cut out of wood that are currently facing each other, face to face. The, "-" part in the middle is also cut out from wood, Bit take the shade of a dash.
Like this if it makes any sense.
(the electronics are completely mounted in the open air, directly attached to the wood.)
(Looking from a angle, (straight on it would make the, "H" shape.
This will slide down PERFECTLY into the rocket tubing attached to the shock cord. I have to go and wont be able to expand on my ideas anymore at the time. If there is anything I have missed please expand on my post Mr. Kilber.
I had to delete the picture I made for the ASP because the format in the forum messed it up if you know what I mean.
The ASP is deployed from the rocket at apogee (the highest point in the flight.) It descends on a large parachute and *the sides of the ASP are open.* This allows atmospheric gases to come in contact with the CO2 sensor. This prevents the rocket's exhaust gases (which may contain CO2) from contaminating the sensor/samples since the rocket descends on a separate parachute.
*See attached picture* and say "Cheese" :smilewinkgrin:
Mr. Kibler
Oh, I forgot all about that, but I did know it last year. That's right. That'll work fine, assuming it's the measurements on the way down that matter to you.
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Our big public launch is this weekend, and the weather is supposed to be perfect. I'm planning to fly my GPS transmitter again, and perhaps fly a 3" dual deployment rocket, going a little higher than I'm used to going. Then it's range duty. I'll be pushing the button for some very interesting rockets this weekend. I can't wait.
Sorry I haven't been on the forum recently. I was busy kind of adapting to high school and finishing up my summer project.
Have we attached the parachute to the ASP yet? Or are we going to do that when we arrive at Nevada?
Justin
A couple of times a year we see someone's rocket separate into two pieces, and either the flyer is slapping himself on the head because he realizes he forgot to connect a quick link, or later in the postmortem we find that it wasn't connected. When I mentor a certification flight I do always double check that part.
Sylvie,
Four or five years ago, and just when they had the weight and parachite size of their TARC rocket dialed in to perfection, another group of Rocketeers made a qualification flight but they forgot to check the quick link. It wasn't closed and they demolished a well-crafted aerospace vehicle. Ouch! They learned a quick lesson about quick links, but more importantly they learned that it''s very important to write and follow a pre-flight checklist. Rocketeers, do we have one for Nevada...?
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I'm in DC and we're dropping Chrisopher off at George Washington University which is just blocks from the big Palin-Glen Back rally on the Washington Mall. I hope we can get in and out of campus smoothly because it's a loooooooong ride back to NH tonight.
What motor are you flying on this weekend: a 29, 38 or 54 mm? Have you set a target altitude? Is your rocket scratch-built? Doual deployment is always the safe and sane idea on an expen$ive rocket. I'm eager to hear how your transmitter works! Keep me posted!
From DC,
Mark and Chris and Mama K
I'll also make my fourth attempt to ignite an ancient 29mm F40-7 - I've sanded the surfaces, painted the grains with pyrogen, and scraped up the face of the delay grain. I'm not that confident that it'll go, though.
Rocketeers,
YES! We need to write a procedure. We still need:
1) To know how to convert CO2 mV to ppm and,
2) A pre-flight loading procedure/ checklist.
What batteries need to charged? When should voltage be checked? Who checks it? Where is that information recorded? How much voltage is needed to power each electronic device? What gets loaded into the rocket 1st, 2nd, 3rd, etc? When is the ASP-s 2turned on (remember that it needs to be "pre-heated" or warmed up before flight)? Will you check everything to make sure it's opertional before you load it? How is the parachute loaded? When, and by whom? What's the post-flight power-down sequence (after the ASP lands)? We don't want to lose data! What frequencies will the shortwave transmitters be on? How do you set them? How much battery power do they require before they shut off? Who will operate the SW receivers?
Sean and Andrew, you were at ARLISS last year. Please step in and lead us through this. Thanks!
From DC,
Mr. Kibler
Sorry I havent been on the forum lately, I had been checking it and it was stuck on page 40 and about an hour ago I looked at it again and BOOM! There were another 2 whole pages of posts dated back to August 20th. So then I had to do much catching up.
We need to charge every single battery (remote car battery, GPS battery, "walkie talkie" batteries, the other ones I know I am forgetting). Last year I believe we checked the battery voltage right before we launched. I think last year we loaded the ASP in first, followed by the main parachute, and then our parachute bag (are we going to use one of those again this year Mr.Kibler?). Seeing how we need to preheat the ASP-2 before we launch we should turn it on while we test voltage and correct me if I am wrong, but it takes a good 30-40 minutes to put everything in the rocket, get the rocket out to the launch pad, get the rocket all ready to launch, then actually launching it. I think it will be a good idea to check to make sure everything is operational before we launch. I believe that the parachute is one of the last things that get loaded, Andrew and I know how to fold them so we can do that together.
Are the short wave transmitters the "walkie talkies" we used last year? Last year we were in "teams". Andrew and I were together with someone in their trailer (I forget his name) and we were reading off the altitude to you.
Sean
You're right on track. Yes, we need to replace any old batteries with new ones and charge any of the batteries that are rechargeable. These include:
1) The large orange nickel-cadmium (Ni-Cd) battery on the ASP platform (*this powers the BOE and the MAWD.)
2) The battery on the orange rectangular Garmin transmitter, and
3) The battery in the handheld shortwave receiver. This reads out the ASP's location in longitude and latitude.
I think all the other batteries and replaceable; and so they should be replaced. These include:
4) The small back-up Alt-Acc altimeter (AA battery)
5) The rectangular 9-V lithium battery mounted on the ASP platform (*what does it go to)
6) All the batteries in the various handheld receivers and "walkie-talkies" we'll use to communicate:
A) The Garmin Astro 220
C) The Yaesu VX-8R transmitter-receiver (rechargeable)
D) The "walkie-talkies"
7) What else...?
You mentioned working in teams. Who will work with whom? We have five students, two parents, and me (I'll bet you forgot about me and the parents; can you use us on some mission tasks?) Use your skills and resources (people and materials) strategically and to our best advantage. Don't put someone on a launch-critical task(s) if they're not sure what they're doing. It's critical that everyone in each two-person team know exactly what they're responsible for, how to do it, and how to solve any problems they encounter. So Andrew, Sean, and Dylan: who will be paired with whom, and what will each team be doing...?
Sean, I'm glad your remembered that we used a parachute deployment bag last year; did we use one on BOTH flights...? Where is the one from the first flight? What tasks are you most confident doing? You'll probably be paired with one of the new team members so you can lead and teach. Again, good work! I'm eager to hear back from Andrew and the rest of the team.
Back from DC,
Mr. Kibler
What do you know about the "Bloom box" fuel cell? It sounds like it works something like the CO2 sensor, converting O2 into E instead of using CO2 NASICON. Do you think there's NASICON in the Bloom box? Couldn't we do the same thing while using CO2 instead of O2... hmmmmm.... (patent pending - ARLISS Team New Hampshire.) Maybe a new funding source for our projects! Maybe we should talk to a Silicon Valley venture capitalist. I think the Roceketeers missed the significance when you told them about NASICON as an excellent topic to be researching now.
Bloom box: "...each "power plant-in-a-box"... is full of thin fuel cells, bundled and packaged into an outdoor-safe case. The individual cells soak up oxygen on one side, "and fuel on the other [NASICON]?. The two combine within the cell to create a chemical reaction that produces electricity... There's no need for burning or combustion" but it still requires some form of fuel to work. What kind is up to the owner.
"Our system can use fossil fuels like natural gas. Our system can use renewable fuels like landfill gas, bio-gas," Sridhar says. "We can use solar."
Video link: http://www.engadget.com/2010/02/22/the-bloom-box-a-power-plant-for-the-home-video/
Curious,
Mark
***Mr. Kibler***
I understand what is beginning the procedure, (us turning the sensors on and all of that), but what are we ending with? Are we going all the way to the point of where we multiply the mV to get ppm? Or are we just covering to the point where you have all of the data needed to find the constant, but not actually what to do after that? I think we really have to get started on this because everyone is in school for most of the day's time and the amount of homework is really building up. Also since we will have to make up work for high school before we get to go on the trip for the missed days.
Your right. We really need to get working on this procedure since time is very limited because of school. Regarding the work for the missed days of school, I think we need to ask all of our teachers for any work that will be handed out and due that week so we can bring it to Nevada and use some of our free time on it.
Justin
Justin,
I'm glad to see that you're thinking and planning ahead. That's part of the learning from this project.
Yes, you will want to let your teachers know that you'll be gone September 14-18, ask for your homework ahead of time, and then bring it with you to Nevada. I've already spoken with the Principal and he'll be looking for a letter from each of you, from me. We'll have homework time set aside each evening at the hotel in Nevada (better remind Mike, Sean, and Dylan. I think Andrew is all set. He planned ahead...)
Mr. Kibler