MaxTrax is reborn

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brockrwood

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I bought an Estes “MaxTrax” starter set back in the early 2000’s when I was becoming a BAR.

The MaxTrax rocket came wit a unique nose cone. The nose was this foam rubber sort of thing with some electronics in it. At ejection, the nose separated from the rocket and plunged to earth on a streamer until it (sometimes) bounced when it impacted terra firma.

The electronics somehow measured the time from ejection to the time of impact and then calculated the altitude at ejection based on how long it took for the nose to hit the ground.

The system sort of worked but often the impact of the nose hitting the ground was not enough force to be recognized by the electronics.

It wad also easy to lose the nose, permanently, in tall weeds.

That is what happened to my MaxTrax: After a few flights, I lost the nose and never found it.

The noseless MaxTrax sat in my parts bin for many years.

Yesterday I pulled it out and realized it is a BT-56 size body tube rocket. That is a perfect use for one of the black, BT-56 nose cones in the 4-pack sitting in my parts bin.

(The MaxTrax is very similar to a number of BT-56 sized RTF and ARTF rockets Estes made in the early 2000’s. The “Chrome Domes” come to mind.)

Anyway, the old shock cord had dry rotted, so I replaced it with a modified G. Harry Stine “shock lock” type shock cord mount using 100 pound kevlar thread. That is glued as deep into the body tube as I can get it using Titebond “Original” wood hlue. It is drying now.

I put 9 grams of clay into the nose to give the fairly light, plastic nose cone some weight (the old nose was fairly hefty because of the electronics and foam rubber).

I am not sure which parachute to use in it. I may just use an old Quest 14” parachute I have in the parts bin. I may make a new parachute just for the MaxTrax. The “recovered weight”, with a spent engine, per the postal scale, is 3.175 ounces. G. Harry Stine’s rule of thumb is 44 square inches of parachute per ounce of recovered weight. The total area is 139.7 square inches. A hexagon of 139.7 square inches eould be 12.7 inches, flat to flat. The Quest parachute is slightly big for this rocket.

Anyway, see the renovation pics. We will fly it tomorrow for Father’s day and see if the rebuilt MaxTrax flies straight and true!

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Nicely done. I liked those BT-56ers, it was a good way to make a small rocket feel bigger than it was, and introduce a variety into a fleet.

Are you aware of any way to clone or reproduce the stock nose? Primitive and less-than-practical as it may be, I still think it’d be kind of cool to fly vintage equipment.
 
Nicely done. I liked those BT-56ers, it was a good way to make a small rocket feel bigger than it was, and introduce a variety into a fleet.

Are you aware of any way to clone or reproduce the stock nose? Primitive and less-than-practical as it may be, I still think it’d be kind of cool to fly vintage equipment.
It would be possible to make a balsa nose cone similar to the blunt, foam nose of the MaxTrax. As for the electronics to determine altitude, a simpler method is to just use the Bill Stine “penny taped to a streamer” method. See pages 269-271 of the Handbook of Model Rocketry, Sixth Edition.
 
It would be possible to make a balsa nose cone similar to the blunt, foam nose of the MaxTrax. As for the electronics to determine altitude, a simpler method is to just use the Bill Stine “penny taped to a streamer” method. See pages 269-271 of the Handbook of Model Rocketry, Sixth Edition.
Interesting. I’ve got the Seventh. Maybe I could dig that out or find a PDF of the Sixth.

That book is in desperate need of an update. So many cool things have been invented, perfected, discovered since 2004. Some of the rules have changed and some things have sadly undergone shrinkage or even gone the way of the dodo.
 
Interesting. I’ve got the Seventh. Maybe I could dig that out or find a PDF of the Sixth.

That book is in desperate need of an update. So many cool things have been invented, perfected, discovered since 2004. Some of the rules have changed and some things have sadly undergone shrinkage or even gone the way of the dodo.
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I think the same text and illustrations are in the 7th Edition. Probably near the same page numbers.
 
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I think the same text and illustrations are in the 7th Edition. Probably near the same page numbers.

I think the idea is that the penny basically accelerates to terminal velocity in less than s second. So, you just count the second on a stop watch and there is your altitude. The streamer is just so you can see it. Of course, the altitude is from ejection, not apogee. But it is in the ballpark.
 
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I think the same text and illustrations are in the 7th Edition. Probably near the same page numbers.

I think the idea is that the penny basically accelerates to terminal velocity in less than s second. So, you just count the second on a stop watch and there is your altitude. The streamer is just so you can see it. Of course, the altitude is from ejection, not apogee. But it is in the ballpark.
Interesting. I really should break that out more often, there’s some good stuff in there that I forget about.
 
Interesting. I really should break that out more often, there’s some good stuff in there that I forget about.
The Bill Stine standard altitude marker. It’s just a penny taped to a 12 inch long, thin plastic streamer. It is supposed to fall at a constant 18 feet per second. You wait for ejection and the start a stopwatch. When it hits the ground, you stop the stopwatch. Multiply the number of seconds by 18 and that should be the altitude, in feet, at ejection.



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Nice rebuild. I do enjoy bringing old rockets back and giving them new life.

For reference. I have a few of the metallic series, Chrome Domes style rockets and they are pretty robust. I often fly them on C6-7's with 9" chutes if there is a hard surface nearby otherwise I fly with a 2"x48" foil streamer if it's coming down in soft grass. Also, none of mine have needed nose weight for stability.

I wish the BT56 tubes were more common as I have three of those 4pk nose cones hanging on the wall.
 
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