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Estes - MaxTrax {Kit} [?-?]

Construction Rating:
Flight Rating:
Overall Rating:

Contributed by Mark Fisher

Estes MaxTraxBrief:
A new member showed up at our launch one weekend with a MaxTrax (EST1434), a new starter set from Estes that included an altimeter payload. He had flown it once before and it had claimed an altitude of over 700 feet on a C6-5. When he flew it at our launch, he used the other included motor, a B6-4, and it registered over 350 feet. The shock cord separated, but after some repairs carried out by some of our other members, the bird flew again that day.

At the time, few on-line vendors even listed the MaxTrax, and those that did had it marked as "overdue" or "not released". The flyer in question found his at a local Meijer, and as I had to go get cat food that evening ("uh ... yea, cat food, that's the ticket"), I stopped by the new rocket display at my local store, and there one was. The price was a stunning $21.99 (list is $39.99 and the cheapest I saw it on-line was ~$28), so I snapped it up.

Recovery systems, as noted below.

The altimeter is housed in a black styrene capsule that fits into the body tube. On the other end is a foam rubber nose cone tip that fits over the molded "thumb" of the altimeter bay. Despite claims to the contrary, two 1.5 V calculator button cells for the device are included. A nice touch. Mine were Vinnic model L1154, though the more common silver oxide models 357 and A76 would last longer. Only one is required so the other is a spare. A very nice touch. To install the battery, the capsule's rubber tip and two tiny, deeply recessed Phillips head screws must be removed and the halves folded open. Estes MaxTraxThe battery fits in a molded holder in the "thumb" with a flip-away upper clip, and the altimeter is in the body.

The electronics are a custom PC board with a single chip covered in carrier material. The board also mounts the on-off switch, LCD display and shock sensor. Off-board is the ejection-detect switch that is held open by the body tube, and closes when the motor charge separates the capsule from the rocket. With only three moving parts and minimal wiring, the device promised to be relatively durable. I was a bit worried that ejection gasses might enter the bay though the two switch openings, but I've yet to see any evidence of that.

As I had designs on this little gizmo for some other birds, I wanted the thing back, so I modified the MaxTrax carrier rocket extensively before its first flight. I added a length of 300# Kevlar® and upgraded the elastic to 1/4 inch from the included 1/8th inch wide junk. I also replaced the included pre-built 12-inch plastic chute with the same size Rogue nylon unit, and added an HSPP-4Y Medium HeatShield from Pratt Hobbies. The altimeter capsule is supposed to recover by streamer, but as our launch site is surrounded by tall grass, I added a large snap-swivel to the elastic and hooked it to that. Total dry weight after the modifications was three ounces even, and with an estimated drag coefficient of 0.573, I predicted the altitudes found in the estimated performance table below.

Estimated Performance

Engine(s) AGL(ft.) Speed(ft./sec.) Accel(Gs)
B6-4 220 110 10.8
C6-5 620 200 12.2
D21-7 1,395 490 29.2

As Estes only requires you to assemble the pad, insert the included battery and attach the parachute to the shock cord, the assembly of the bird in stock configuration is pretty easy. As it is likely to fail after just a few flights, though, I'd only rate this bird a 2 on the Essence scale for assembly, needs improvement.

The bird is a standard Estes BT-56-based RTF, with quick-change motor mount and the new two-lug one-piece launch guide. The shock cord is attached though a hole in the body tube to this, making for one of Estes' worst mounts ever, and that's saying something. The body wrap is a nice silver holographic sticker, so the bird will be easy to see in the air, and overall, the rocket is a rather good-looking example of the RTF genre. The launch system is Estes' standard Electron Beam, in all black.

Construction Rating: 2 out of 5

Flight: Estes MaxTrax Flight
I flew the bird nine times in my configuration, on five B6-4s and four C6-5s. I didn't get an altitude reading once. I called Estes and they said that the reason the thing wasn't working was because I had it tied to the parachute. I reconfigured my MaxTrax back to the way Estes intended it to be, swapping out the 12 inch parachute for a 9 inch version. I flew her on the recommended motors again, with the following results.

Motor Descent(sec) Alt(feet) Alt(Meters) Notes
B6-4 3.87 0 0 Not armed, hit road
B6-4 5.22 182.3 55.6  
B6-4 6.16 216.8 66.1  
C6-5 12.82 228.4 69.8  
C6-5 0 422.1 128.7  
C6-5 0 148.2 45.2  
C6-5 16.47 598.9 182.6 Hit road
C6-5 13.97     Not armed
C6-5 16.19 379.4 115.7
C6-5 16.41 741.9 226.2 New unit
C6-5 17.03 313.2 95.5  
C6-5 13.39     Lost

Fearing that the unit I had was defective, I broke out my back-up MaxTrax and flew it for the last three flights. The ejection sense switch on this unit was intermittent, and it took a little adjusting to get it to work consistently. The two readings I got from it were just as bad as the ones from the first unit, and this capsule was lost in only moderately tall grass on the third flight. Two of us saw right where it came down, but we gave up after thirty minutes of searching. The bird itself survived its repeated flights without damage.

This is how I think MaxTrax works. The ejection sense switch starts an internal timer, which is stopped by the shock switch when the unit hits the ground. The assumed descent rate is then multiplied by the elapsed time to determine the altitude. If the shock switch is activated prior to touchdown (the capsule does tumble pretty badly, the streamers did not keep either of my units pointed straight down), the altitude will be low. If the shock switch isn't activated at touchdown (as it will not be when tied to a parachute), no altitude will be displayed. If the capsule does not fall at the assumed descent rate, the altitude will be erroneous. While the idea behind the MaxTrax is ingenious, it just doesn't work in practice, at least not the way Estes has implemented it.

The bird is over stable and does have a tendency to weathercock. At 2.5 ounces in stock trim, the B6-4 is late, but the C6-5 is nearly perfect. These are the only two Estes motors you can fly in the stock bird, though, limiting the altimeter to two general altitudes, somewhat boring. If it worked, that is; the values I got from my two units just aren't believable. I'd rate the flight characteristics of the MaxTrax a one on the Essence scale, needs a lot of improvement.

Flight Rating: 1 out of 5

When I initially saw MaxTrax, I imagined all the kids that would be using it for their school science projects. Once I got some experience with the thing, I realized that there were going to be a whole lot tearful young scientists and frustrated Dads this year. Twenty-one flights on an RTF has got to be some kind of record, but I'm afraid that my MaxTrax's durability was due to my preemptive mods. Given the overall quality of the bird, poor altimeter design, limited flight scope and ensuing high possibility of disappointment, I'd rate the MaxTrax a 1½ overall on the Essence scale, needs drastic improvement.

Overall Rating: 1 out of 5

    Flight Log

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

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