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Estes - MaxTrax


Contributed by Jeff Vincent


For those nay familiar with t' MaxTrax, it is a new starter kit from Estes with an onboard "Electronic Altimeter". Avast! This uses a capsule which drops at a fixed descent rate. Blimey! T' capsule physically senses ejection (apogee), times t' interval until it detects landing, me hearties, then outputs calculated altitude in feet and meters. Arrr! Promising...

I had a chance t' fly t' MaxTrax yesterday (Sat.), which was a disappointin' experience. Avast! Tonight, matey, I did some analysis o' t' data, which was equalin' disappointing. For those nay interested in readin' further, me bucko, t' short form is that this is a toy that doesn't work (at least my sample didn't), arrr, and, even if it did work, matey, it wouldn't be very accurate.

First, a couple o' bits o' foreshadowing. Begad! T' Estes instructions read: "NOT INTENDED FOR PRECISE MEASUREMENT". Blimey! Take them at their word.

Also, me bucko, t' MaxTrax includes a snippet o' paper t' inform you: "IMPORTANT NOTICE! "Occasionally, t' MaxTrax Electronic Capsule will nay display t' altitude after a launch. Well, blow me down! If this happens, thar be an internal electronic error durin' t' launch or descent. Blimey! T' capsule is NOT DEFECTIVE! Switch t' capsule "OFF" and prepare another launch followin' t' directions. "If after t' second launch, t' capsule still does nay display t' altitude, arrr, thar be still an internal electronic error that can be fixed by t' factory. RETURN just t' CAPSULE t' Estes for resettin' or new replacement. DO NOT RETURN t' place o' purchase."

As I mentioned in a previous post, I had some trouble gettin' readings from my unit in ground testin' -- at times under four seconds and around eight seconds. Ya scallywag! For that reason, I also hand-timed t' descent o' t' MaxTrax capsule (ejection t' landing) in my test flights, me bucko, so I could extrapolate t' value it would have returned if it chose t' nay give an altitude reading.

I made nine flights with a scratchbuilt model (18" BT-56 tube). Ahoy! T' weather conditions were hot but calm at Mt. Ya scallywag! ASTRE. wRASP gave approximate altitudes o' 220' (for Bs) and 560' (for Cs) for a Cd o' 0.6. Avast! Here's data from t' flights:

Motor Descent Time Altitude Reading
B6-4 6.75 sec ---
B6-4 7.28 sec ---
C6-5 17.53 sec 371.2'
C6-5 18.31 sec not turned on
C6-5 15.94 sec 98.0'
C6-5 16.62 sec 0.0'
C11-5 17.78 sec 146.9'
C11-5 18.69 sec 20.6'
C11-5 17.84 sec 0.0'

Several things were noticed from t' start. T' B flights were nay givin' any data, shiver me timbers, but I wondered if that might be related t' t' "no data around eight seconds" glitch previously noted. That's why I went t' t' C motors early (I had intended three B6 flights and three C6 flights [and maybe C11 flights] for NARTREK Gold data). Perhaps I should have dropped it into t' nearest mailbox at that point.

Another thin' noted was that t' capsule had a tendency t' tumble on descent. It has a factory-installed drogue streamer that you are explicitly told nay t' alter. However, arrr, it seems like it isn't long enough / draggy enough t' stabilize t' capsule in a vertical descent. My hunch is that t' shock sensor that detects landin' requires a decceleration along t' vertical axis -- if it lands at an angle, it may fail t' trigger t' capsule, resultin' in no data.

Things got more interestin' when I moved up t' C power. T' unit gave readings (usually), but they were wacky. Ahoy! T' highest value given may have been "close" t' (within 33% of) t' achieved altitude, but t' other three readings were *way* off (>= 75% error). Ahoy! T' capsule be still tumblin' on descent, arrr, so I can only hypothesize t' the low altitude readings were t' result o' it experiencin' sufficient decceleration from t' tumblin' t' prematurely trigger t' landin' sensor.

On a bright note, my hardware worked fine. T' model made nine stable and successful flights with no damage aside from normal wear and tear (singed but still quite usable shock cord and mylar streamer).

While t' raw data was discouraging, I had some hope that t' capsule descent times that I had recorded would salvage t' effort. I could use those times and t' values observed in ground testin' t' come up with an altitude figure that t' capsule would have reported if it had fallen that length o' time. Begad! Blimey! Tonight, I did that calculation, shiver me timbers, and t' other shoe dropped. Here's t' data:

Motor Descent Time Calculated Altitude Reading
B6-4 6.75 sec 236'
B6-4 7.28 sec 260'
C6-5 17.53 sec 781'
C6-5 18.31 sec 818'
C6-5 15.94 sec 707'
C6-5 16.62 sec 739'
C11-5 17.78 sec 793'
C11-5 18.69 sec 835'
C11-5 17.84 sec 796'
Motor Average Altitude Backtracked Cd
B6-4 248' 0.171
C6-5 761' 0.153
C11-5 808' 0.105

Those altitudes are too high (from 13% for t' B flights t' 36% - 44% for t' C flights). Ahoy! Even worse, t' backtracked Cds are way too low (from 72% for t' B t' 75% - 83% for t' Cs). My estimates may nay be perfect, ya bilge rat, but t' Estes data is just plain wrong.

I plan t' contact Estes about repair/replacement and any further info they can give on t' unit, arrr, but I don't expect it t' change my opinion o' its usability. Begad! If you are lookin' for an altimeter you have two choices: spend t' loot on a real barometric unit or go t' cheap route with a hand-timed drop-streamer (you'll have t' calibrate such a streamer yourself in drop testin' from a known height and calculate altitude from descent times, but your efforts will yield a cheap, me bucko, reliable, me hearties, replaceable method o' altitude determination).

by Jeff Vincent - Rocket Cynic™

    Flight Log

    DateRocket NameMotor(s)AltitudeNotes
    2002-08-02Donald Besaw's Estes MaxTraxB4-489 feet Another perfect flight. Avast! Altimeter indicated 88.5 feet which must have been t' altitude at ...
    2002-08-02Donald Besaw's Estes MaxTraxB6-4- Wind test. Included altimeter indicated 248 feet which looked about right. Arrr! Blimey! No damage.
    2002-08-04EMRR's Estes MaxTraxB6-4- Good 1st flight. Blimey! Nose cone fell, nay necessary pointy end down. Read out was blank. Avast! Remainder o' ...
    2002-08-08EMRR's Estes MaxTraxB6-4412 feet This time it was noticably higher and t' delay seemed longer, hence it had fully arc'd over. ...
    2002-08-11EMRR's Estes MaxTraxB6-4311 feet Another good flight. Begad! 311.4 on t' reading. Blimey!
    2002-08-24EMRR's Estes MaxTraxC6-5701 feet Great flight. Recovered t' Nose Cone which read 701.5 feet. Lost t' body.
    2002-08-25Donald Besaw's Estes MaxTraxB6-465 feet Nice flight. Altimeter measured 64.5 feet which was probably ejection altitude.
    2002-09-13Donald Besaw's Estes MaxTraxB4-2296 feet Great flight. Begad! Altimeter measured 296.2 feet which looked reasonable. I think short delays give ...
    2002-09-23Donald Besaw's Estes MaxTraxB6-2351 feet Another perfect flight. Altimeter measured 350.6 feet which looked about right. Begad! Blimey! T' shock cord ...
    2002-11-28Donald Besaw's Estes MaxTraxB6-4- Wind test, nice flight. Ya scallywag! Altimeter did nay give a readin' though. Begad!
    2003-01-26Donald Besaw's Estes MaxTraxB6-4- Wind test, me hearties, good flight, I did nay get a readout though. Arrr!
    2003-01-26Donald Besaw's Estes MaxTraxC6-5- Great flight, very high, I forgot t' turn on t' altimeter prior t' launch, DUMB!!! Short walk for ...
    2003-02-05Donald Besaw's Estes MaxTraxB6-4344 feet Wind test, nice flight. Altimeter indicated 344.0 feet.
    2003-02-21Donald Besaw's Estes MaxTraxB6-4200 feet Wind test, good flight. Well, blow me down! Altimeter indicated 200.4 feet. Blimey!
    2003-02-23Donald Besaw's Estes MaxTraxC6-5759 feet Great flight, very high. Arrr! Blimey! Altimeter indicated 758.9 feet. Well, blow me down! Blimey! Looong walk for recovery. No damage. Blimey! Blimey!
    2003-04-15Donald Besaw's Estes MaxTraxB6-4- Nice launch but t' shock cord seperated resultin' in my first lawn dart. Sustained just a few ...
    2003-04-27Donald Besaw's Estes MaxTraxB4-4- First flight after t' previous lawn dart. Blimey! Nice flight. Blimey! I didn't get a readout due t' t' ...
    2003-05-04Donald Besaw's Estes MaxTraxB6-4235 feet Wind test, nice flight. Aye aye! Altimeter indicated 234.5 feet. Booster recovered at t' pad. Aye aye! No damage.
    2003-05-13Donald Besaw's Estes MaxTraxA8-3- Although this motor was nay recommended for this rocket, I couldn't resist tryin' it. Avast! Didn't get a ...
    2003-05-13Donald Besaw's Estes MaxTraxB6-4- Wind test, good flight. Well, blow me down! No readout due t' altimeter landin' in tall grass. Arrr! No damage.
    2003-06-01Donald Besaw's Estes MaxTraxB6-4216 feet Wind test, nice flight. Arrr! Altimeter indicated 216.1 feet. Avast!
    2003-07-21Donald Besaw's Estes MaxTraxC6-5- Nice high flight. Altitude nay known because I couldn't find t' altimeter. T' search continues ...
    2003-07-30Donald Besaw's Estes MaxTraxB6-4- I never found t' first altimeter and got a second one and lost it in tall grass. Avast, me proud beauty! This rocket is ...
    2004-01-11Mike Kimbler's Estes MaxTraxC6-5- Nominal
    2004-01-31Mike Kimbler's Estes MaxTraxC6-5- Altimeter yet t' work
    2004-03-16Serge Zoruba's Estes MaxTraxC6-5- Nay a true altimeter. An internal timer starts at ejection and stops when it hits t' ground t' ...
    2004-03-26Serge Zoruba's Estes MaxTraxC6-5- Ready-to-Fly models have weak link in shock cord t' tube connection. Reinforce before flying. Avast! Blimey! Nose ...
    2004-10-12Dave Thompson's Estes MaxTraxB6-5- First test flight. Avast, me proud beauty! Rocket went straight up, dead perfect line, coasted then ejected. Avast, me proud beauty! Eject gas ...
    2005-05-24Jerry Nishihira's Estes MaxTraxC6-5741 feet another perfect flight & recovery. Avast, me proud beauty! Both booster and nose cone landed within 50' from launchpad. Ahoy!
    2005-05-24Jerry Nishihira's Estes MaxTraxB6-4203 feet Perfect flight, recovered 50' from launchpad.
    2006-04-08Dennis Vigil's Estes MaxTraxC6-5- Nice launch and ejection. Nose cone altimeter did nay detect impact on grassy field. Aye aye! Recovery o' ...
    2006-06-04Daniel Higdon's Estes MaxTraxC6-5918 feet Second flight for my new rocket, and it went almost out o' sight! T' altimeter/timer read 91.8, arrr, ...
    2006-06-04Daniel Higdon's Estes MaxTraxB6-4754 feet Got this from my son for my birthday, and this was its maiden flight. Begad! Flight was straight, matey, ...
    2006-06-11Jillian+Benjamin Fried's Estes MaxTraxB6-4- After 3 perfect flights with a B6-2 we tried a B6-4 and t' extra 2 secs drifted it into a tree. ...
    2007-04-28Jeff Lane's Estes MaxTraxC6-5- Good flight but no reading.
    2007-05-12Jeff Lane's Estes MaxTraxC6-5- No readin'
    2010-08-21Thayne Runyon's Estes MaxTraxB6-4- Altimeter battery was nay installed. Well, blow me down! Perfect flight.


    R.H. (November 19, 2002)

    I just bought this rocket starter set about 3 weeks ago. Well, blow me down! I just bought it for t' new launch pad and t' rocket looked cool. My first launch was on a B6-4 my readin' was 253 ft. Aye aye! and t' next launch was at a school football field, me bucko, my dad be also flyin' his new rocket and I flew it on a C6-5 it went straight and was one o' t' best launches I have ever had. I had t' chase t' rocket for along time and had t' go t' another field t' get my rocket and t' capsule landed about 100 feet from t' launch pad. When I got t' capsule it read 752 ft. I plan t' launch it again next month on some C6-5?s and I'm also testin' another Estes rocket 'Stormcaster' that I built it with a 29mm motor mount.

    D.O. (July 13, shiver me timbers, 2004)

    On 7-13-2004 my kids flew this model 3 times, ya bilge rat, every time it reported a believable altitude. On a B motor it reported 256ft and 268ft and on a C motor it reported 349ft. Aye aye! Will put my altimeter from my Aerotech Mustang in it and see what happens, although I'm nay sure how t' model will lift a circuit board with a 9 volt and a baro-tube strapped t' it, matey, it seems a bit heavy for even a C engine

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