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Model Forum / General / Rockets / March 2006PICO Altimeter Query...
Hi to all - http://www.picoalt.com/ Is anybody familiar with these units? I'm considering getting a P1 to put in my scratch builds. While I realize it's not a big expenditure, I just thought I might find out if anybody has any experience with these units. If this works out O.K., I'll probably go for onr of the logging units.Thanks in advance for any input you might be able to offer. Bob352 > http://www.picoalt.com/ > Is anybody familiar with these units? I'm a satisfied customer. :-) I used a couple of P1's at an NAR contest last spring, they worked fine. I've also used older versions of the picoAlt altimeters, plus some of the timers. I do feel I should point out that by the time you add a power supply, the altimeter is no longer so tiny. The 2032 "button" cells that Robert suggests for a power supply are 20mm diameter, for instance. I used smaller silver-oxide cells to fit the device inside a BT-5. You could use a couple of 10mm-diameter super capacitors to fit the device inside a 10mm tube. But however you power the P1 you will have an overall package 3-5 times as big (size & weight) as the P1 alone. The P1 isn't unique in this situation; I know of no device that, including the power supply, is smaller. That said, the P1 works great, is reliable, and the price is right.  SignatureSteve Humphrey (replace "spambait" with "merlinus" to respond directly to me) Thanks, Steve. I appreciate the input. That being said, I've got a better idea of what I'm up against, since most of the models I'd use it in are at least BT-50 or so (well, a couple of 3" diameter "experiments"), but that should work fine. After all, you said it:'the price is right'! Thanks again, Bob352 Steve is right there Bob. The P1 is a pain to power, but it does give the option to the flier how complex he wants the system. That was the point. I optionally supply the 2032 cells as a starting point. Always easier to troubleshoot an issue if you have a known good setup ya know. Robert DeHate > Thanks, Steve. I appreciate the input. That being said, I've got a > better idea of what I'm up against, since most of the models I'd use it [quoted text clipped - 3 lines] > Thanks again, > Bob352 > I used a couple of P1's at an NAR contest last spring, they worked fine. > I've also used older versions of the picoAlt altimeters, plus some of the > timers. Hi Steve, are they finnaly allowing the use of altimeters in NAR contests ? Sounds like a move forward. > ... are they finnaly allowing the use of altimeters in NAR contests ? Sort of. For now the use of altimeters requires approval, per section 14.8 Novel Methods: "The NAR Contest Board must approve novel altitude determination methods before the results are accepted for competition." But the Contest Board chair seems inclined to approve the use of altimeters for contest use (but probably not for records). Here are the results for one such contest: http://www.narhams.org/contests/zolmir-2.html All three of those altitude events used altimeters. The contestants could provide their own altimeters, subject to these restrictions: "Any model with at least 12-bit ADC will be allowed. Altimeter failures will be treated as Track Lost. ... Additional procedures will be in place at check-in to verify altimeters are unmodified, commercially-produced models and are in standby mode prior to launch." Several altimeters were provided by the contest organizers for those who didn't have any. SignatureSteve Humphrey (replace "spambait" with "merlinus" to respond directly to me) > But the Contest Board chair seems inclined to approve the use of > altimeters for contest use (but probably not for records). This is good news. I had asked the CB a few years back and it got sort of a cold shoulder. They said, "well the (a club name) have done some work on this, but we are not sure...." > This is good news. I had asked the CB a few years back [about using > altimeters in NAR competition] and it got sort of a cold shoulder. Well, try again, but with a specific contest proposal. Let me know what happens. SignatureSteve Humphrey (replace "spambait" with "merlinus" to respond directly to me) The NAR should require at least four things first: 1) Certification of the altimeter brand 2) Use of after-the-fact temperature correction 3) All rockets in a contest should use altimeters or none 4) Altimeters should be disallowed during temperature inversions Certification would be by experiment, and also by method. Most altimeters use approximations, so that computations can be made to fit on embedded hardware. These approximations can over-estimate in some regions and under-estimate in others. In principle, one can choose an altimeter to game a contest. Best case would be to require raw readings be downloaded to laptop software, which would use no approximation. Since the methods are well known, source should be revealed and audited. Temperature would tend to affect all altimeters the same way on the same day. There are exceptions to that, and it would be nice to compare stats from different contests. #3 should be pretty obvious. Altimeter formulas are based on linear temperature lapse with altitude. If hotter air is squatting on top of hotter air, they can be inaccurate. -Larry (Jumping in for no reason as usual) C. > > ... are they finnaly allowing the use of altimeters in NAR contests ? > [quoted text clipped - 16 lines] > Several altimeters were provided by the contest organizers for those who > didn't have any. > Altimeter formulas are based on linear temperature lapse with altitude. > If hotter air is squatting on top of hotter air, they can be inaccurate. But would it not affect all contestants equally? I'd say 3 years of TARC gives a pretty solid basis for using altimeters to track altitude models. The biggest issue I see is that many current competition models would need radical redesigns to allow for altimeter tracking. This would negate all existing records. Take one of my 18mm B-C egglofters as an example. 1/2A Altitude would be another case. In a way, Payload would be the easiest event ot "fix" just by redefining the standard payload from 28g of sand in an 18x70mm tube, to say 60g of electronics and ballast in a 30x100mm tube. But the rockets would all need to be redesigned. And in the case of larger alttiude events, like F Altitude being flown at NARAM, current models are disposable and often never recovered or even seen again. An altimeter makes return required for all events, with the tree rule not applying. And losing a model now carries a significant financial penalty. -- Bob Kaplow NAR # 18L >>> To reply, there's no internet on Mars (yet)! <<< Kaplow Klips & Baffle: http://nira-rocketry.org/Document/MayJun00.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org S&T is becoming this decades Steve Weaver! Bob, As I noted, the temperature would affect all contestants equally on the day of the contest, but there are records, which hold across contests. That's where temperature correction becomes important. Best Regards, -Larry > > Altimeter formulas are based on linear temperature lapse with altitude. > > If hotter air is squatting on top of hotter air, they can be inaccurate. [quoted text clipped - 24 lines] > > S&T is becoming this decades Steve Weaver! >> Altimeter formulas are based on linear temperature lapse with altitude. >> If hotter air is squatting on top of hotter air, they can be inaccurate. > > But would it not affect all contestants equally? Good point. > I'd say 3 years of TARC gives a pretty solid basis for using altimeters to > track altitude models. So does years of TRA contests with large monetary prizes. > The biggest issue I see is that many current competition models would need > radical redesigns to allow for altimeter tracking. This would negate all > existing records. Make Altimeter records, like they do for R/C records >Take one of my 18mm B-C egglofters as an example. 1/2A > Altitude would be another case. In a way, Payload would be the easiest [quoted text clipped - 11 lines] > not applying. And losing a model now carries a significant financial > penalty. Tiny radio trackers will add yet another 28g ;) > And in the case of larger alttiude events, like F Altitude being flown at > NARAM, current models are disposable and often never recovered or even [quoted text clipped - 3 lines] > not applying. And losing a model now carries a significant financial > penalty. It is interesting in that TRA altitude records require the return to read the data. But some like the RDAS and ARTS will read you the data via radio telemetry real time, yet to claim the record, you have to recover the model and have the Prefect observe the results on the altimeter. >The NAR should require at least four things first: > [quoted text clipped - 22 lines] > >-Larry (Jumping in for no reason as usual) C. Altimeter altitude contest events should be added in the usual way as provisional events, to supplement but not replace the traditional Altitude competition events. Choosing to fly altimeter altitude at a particular time of the day, or using weather forecast information may have some minor competitive advantage, but so does picking air, sky, and tracking teams in the traditional contests. It might even encourage learning more about meteorology as a competition skill. What you may see a potential flaw in the system is just of the sport. I just hope that altimeter altitude does not become the last nail in the coffin of traditional tracked altitude competition. Alan Larry, You make a good point there. I had one person ask me to make an altimeter that output pressure. It output the ground pressure and apogee pressure. Then they could calculate the altitude on their own. I would rather see recording type altimeters used so they can verify the data. I know my recording altimeters only store pressure data. The computer calculates the altitude curve. Robert > The NAR should require at least four things first: > [quoted text clipped - 47 lines] > > Steve Humphrey > > (replace "spambait" with "merlinus" to respond directly to me) I'm like the pico altimeters and timers too, they work well >Hi to all - http://www.picoalt.com/ >Is anybody familiar with these units? I'm considering getting a P1 to [quoted text clipped - 3 lines] >units.Thanks in advance for any input you might be able to offer. >Bob352 Dan Winings dan.winings@novaar.org I have used the LO4 logging altimeter and the AA1 accelerometer with good results. Also Robert provides great support!! Mike I use em, abuse em and they keep on working Best altimiter on the market J > Hi to all - http://www.picoalt.com/ > Is anybody familiar with these units? I'm considering getting a P1 to [quoted text clipped - 3 lines] > units.Thanks in advance for any input you might be able to offer. > Bob352 Some excellent testimonials there, Robert...I'll bite! Thanks for all the advice and input. I do appreciate it. Bob352 |
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