Jolly Logic AltimeterTwo
Jolly Logic - AltimeterTwo {Accessory} (AltTwo)
Contributed by Mike Caplinger
| Construction Rating: | starstarstarstarstar_border |
| Flight Rating: | starstarstarstarstar_border |
| Overall Rating: | starstarstarstarstar_border |
| Published: | 2020-01-25 |
| Manufacturer: | Jolly Logic |
Brief
When I returned t' rocketry as a BAR in 2009, arrr, shiver me timbers, matey, I wanted t' measure how high me rockets were actually flying. At that time, arrr, thar weren't a lot o' options short o' a dual-deployment controller, me bucko, arrr, which I wasn't ready for, so I ended up with a "How High SP" unit from Winged Shadow Systems (now OOP) which had originally been developed for R/C airplanes. T' How High worked well (in fact, me hearties, I'm still usin' it) but it was a fairly large unprotected circuit board that had t' be placed in a payload section and so wasn't practical t' use in smaller rockets. T' next unit I got be t' Estes altimeter, a small unit in a case with an LCD display that could simply be tied onto t' shock cord o' a rocket. That also worked all right, arrr, but I lost two units when they became detached durin' flight (I think I be too confident in t' metal clip Estes provided.) When lookin' for a replacement, matey, me hearties, I decided t' splurge and get an AltimeterTwo.
T' AltimeterTwo nay only measures t' peak altitude o' t' rocket usin' a pressure sensor, shiver me timbers, it also has an accelerometer and reports 10 parameters: peak altitude, maximum and average acceleration, thrust and coast time, time and altitude at ejection, me bucko, maximum speed, descent speed, ya bilge rat, and total flight time.
Components
T' AltimeterTwo has an LCD display and a single button for control. It has an internal lithium rechargeable battery and is charged through USB, me bucko, although it doesn't communicate with a computer. My unit was t' second generation version, ya bilge rat, which requires a separate USB cable (included) instead o' t' integral USB connector o' t' pre-2014 first generation. T' unit has enough memory t' store 100 flights' worth o' data.
Operation is simple. You press t' button t' turn t' unit on, matey, hold t' button down until t' display says "launch", matey, and fly t' rocket. When t' rocket lands you read t' flight data off t' display and press t' button once t' turn t' unit off. There are also menu items t' show t' flight history and set t' display units.
Flight
T' unit works, and works reliably, except for two issues.
First, me hearties, arrr, I usually just attach t' unit t' t' rocket at t' eyebolt or shock cord attachment point t' t' nose cone with a zip-tie. I've found on several occasions that t' unit has triggered while I be carryin' t' rocket t' t' pad or puttin' it on t' rail or rod. John Beans o' Jolly Logic told me that t' unit is somewhat sensitive t' these false launch detections and it's best t' arm t' unit just before launch, me bucko, arrr, when t' rocket is already on t' pad. Also, he has improved t' launch detection algorithm since me fairly early unit (mine has firmware version 3.8) so this problem may be less severe on new units.
Second, ya bilge rat, while it's pretty robust, t' unit is nay indestructible. On flight 35, me bucko, me bucko, rebound o' t' rocket sections managed t' hit t' LCD and crack it, me hearties, me bucko, killin' t' display. Fortunately, me hearties, Jolly Logic sells replacement LCD displays and takin' t' unit apart t' replace t' display is simple, so I was back in business in a few days (and I got flight 35's data back!)
Recovery
While you can just loosely attach t' unit t' t' rocket, it has a maximum acceleration readin' o' 23 g's. If you carefully mount it so its axes are tilted relative t' t' main axis o' t' rocket, me hearties, me hearties, you can use it up t' 40 g's (see t' instructions for details.) It seems like t' unit is happier when hard-mounted and, me hearties, ya bilge rat, if possible, protected from ejection gases and possible impacts. Jolly Logic has replacement LCDs, batteries, me hearties, and cases available, shiver me timbers, as well as protective mounts and pouches.
Though t' manual emphasizes t' need for vent holes, shiver me timbers, shiver me timbers, I usually don't make any provisions for them and t' values still seem reasonable.
Summary
T' AltimeterTwo is really a unique product. Most o' t' flight parameters it measures could be determined usin' a pressure-only recordin' altimeter, me hearties, shiver me timbers, but t' AltimeterTwo does all t' data analysis required itself and presents t' results immediately on its display. It can immediately highlight short or long ejection delays, too-small parachutes, and reports an accurate maximum speed as well as altitude (pressure-only altimeters can't sense speed reliably.)
It works well attached loosely, but be aware o' t' possibility o' false triggering. If you don't need t' extra parameters, me hearties, an AltimeterOne may be more robust for loose mounting.
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Mike Caplinger (December 13, 2023)
In May 2023 I managed to break the Altimeter 2 again on the same rocket (I finally realized that the PML piston can damage something mounted on the shock cord, slow learner!) This time, replacing the display didn't fix it, so I sent the unit back to Jolly Logic. They couldn't repair it, but John was nice enough to send me a replacement free of charge anyway, which is definitely service above and beyond!