The most inexpensive 29mm motor retainer....and it works GREAT!!

This little nugget of inspiration came about when I went to my nearest 7-11 for a bottle of Gatoraid. After studying it after swigging down some purple goop, I thought the lid was about the same size as my bodytube for my Quest High-Q.....then it snowballed from there.

After cutting out the bottle about 15mm below the threaded section, I layed down Gorilla glue in the space between the motor mount and the bodytube, then after insertion I put down a little more Gorilla glue so the bottle retainer was completely surrounded by glue. I let it dry for 2 days to make sure everything was fully set. Afterwards I checked the bond, and found it quite strong and rigid.

Assembled view. Still has the spent Aerotech F23-7J engine.


Cap off. If you look, there is a 1.5mm Airgap between the motor mount tube and the plastic retainer. That acts like a insulator so the plastic is fairly well protected. The cap has a cork ring to insulate the cap on the inside. Cork is a pretty good insulator for short durations, and it does have natural flame retarding properties.



End view. The whitish deposits on the cap is from the exhaust gasses from the engine. The cap itself did not receive much in the way of heat from the exhaust. What heat it did get was way below the melting point of this plastic. Threads of the cap were not compromised in any way. Cap was still snug after recovery.




So there you have it. If you got enough pocket change for a bottle of Gatoraid, you have a very lightweight and tough 29mm motor retainer.

Sweet!!!

Truly a Scottish approach to motor retention.

Canny!

o1d_dude said:

Truly a Scottish approach to motor retention.

Canny!

Click to expand...

Not totally.

He bought the drink, didn't dig the empty out of the tip.

Just in case anybody is interested, a 2L pop bottle would be big enough for a 18mm motor mount.....Not sure if the BT-50 tube would work, but it would be a snap to use it for BT-60 tube (aka Big Bertha motor retainer).

COOL
I used the cap from the waterbottle I built my Eggnik out of.
Works great ,as you say.

I think I'm feeling a bit thirsty...

Those'r way cool. I've got a mid-power bird that needs a retention device, will have to give it a go. Also have to look into the soda bottle cap for 18 & 13mm mounts.

Thanx for sharing!

Looks great!

New Ocean said:

Looks great!

Click to expand...

Less filling!

Good job! I would never have thought. I'd like to think I'm a creative and resourceful individual but just when I impress myself, someone outdoes me! I've used PVC fittings for 29mm retainers but that's slick!

Okay, I made another identical motor mount for my Quest Big dog. I officially have 5 flights on my high-Q and 3 for the Big Dog with this retainer, and so far zero signs of failure.

GDJ said:

Okay, I made another identical motor mount for my Quest Big dog. I officially have 5 flights on my high-Q and 3 for the Big Dog with this retainer, and so far zero signs of failure.

Click to expand...

Appreciate the follow-up report. It's nice to have field use data for these types of discoveries. Wanted to try this on one of my small aerotech 29mm rockets, but was concerned about durability. Let me know when you get to 10 launches on one of these. That's about as many launches as I get before I lose a rocket to one of Massachusetts' evil rocket-eating trees. :dark:

Since I first saw this thread, I've been wanting to try it. I bought some Poweraid (it was cheaper), and it fits my 29mm motor sample (an Estes Pro Series II F26-6FJ) beautifully, except... The thrust ring.

Am I missing something here? Are these improvised retainers only for motors that are 29mm the entire length of the motor (e.g. Pro Series II F15-6's, etc), or can they fit a motor with a thrust ring?

Ahh. I see what you're getting at. Okay, some aerotech motors do come with a thrust ring that you would glue on, but failing that a couple laps of good masking tape can work as a thrust ring. On my High-Q I had a motor block at the end of the motor mount but a thrust ring should work fine. There is plenty of room inside my Gatoraid retainer.


......

Or am I missing something?


......

Hi GDJ,

On the F26-6FJ, there is a ring of material that is built into the motor (near the nozzle) that prevents the motor from sliding through the motor tube (and up into the main body of the rocket, where as the F15-6 needs something mounted internally to prevent it from blowing though the inside of the rocket.

When I tested the F26, I couldn't get the cap to come down enough to engage the threads on the Poweraid container (too thin). The Gatoraid looks to have a similar thickness of caps. This isn't an issue for the F15-6 because it requires a motor block which would be installed at the correct length to allow the motor to fit, and the threads to engage. Problem is, I'm not sure I want to limit my builds to only that kind of motor.

I considered doing a retainer from the top of a Tropicana bottle -- the cap would look cool -- but very coarse threads.

Okay! Got it!

Is the motor mount flush with the end of the power aid bottle? You may have to cut the motor mount back 5 or 6mm from the end of the threads. I just checked my High-Q and the motor mount is recessed 5mm from the end of the threads, so the motor actually sits right inside the motor retainer.

I've determined that the 32 oz PowerAid bottle sucks for this purpose.

That said, the plastic TruMoo milk container I got today (as a byproduct of my niece's dinner) from Wendy's looks like it will work beautifully as a 29mm motor retainer. The bottle is clear Polyethylene Terephthalate (aka PET, PETE, or Recycle #1) plastic (the lid is white plastic (CP01 (ABS?)). I haven't tried it with an actual launch, but if the other similar containers I've read about in this thread work, then this one will too I'm sure. Wendy's also offers chocolate milk from TruMoo, but I couldn't tell (100%) from the photograph if the lid is brown or black (looks brown to me).



The lid is easy to cut with a new Xacto #11 blade (even has a convenient thinner part for guiding your cuts). The neck of the bottle needed to have the top five millimeters cut off (but there's a nice little ridge to guide your razor saw). Cutting behind the lower ridge gives you a wide surface (a tad larger (at 41mm) than a BT-60's inner diameter (40.5mm), but could easily be sanded down) that should be good for gluing, and the neck easily slips over the Estes Motor Mount tube (#031360), and securely holds the Pro Series II F26-6FJ motor I have.

K'Tesh said:

I've determined that the 32 oz PowerAid bottle sucks for this purpose.

That said, the plastic TruMoo milk container I got today (as a byproduct of my niece's dinner) from Wendy's looks like it will work beautifully as a 29mm motor retainer. The bottle is clear Polyethylene Terephthalate (aka PET, PETE, or Recycle #1) plastic (the lid is white plastic (CP01 (ABS?)). I haven't tried it with an actual launch, but if the other similar containers I've read about in this thread work, then this one will too I'm sure. Wendy's also offers chocolate milk from TruMoo, but I couldn't tell (100%) from the photograph if the lid is brown or black (looks brown to me).

The lid is easy to cut with a new Xacto #11 blade (even has a convenient thinner part for guiding your cuts). The neck of the bottle needed to have the top five millimeters cut off (but there's a nice little ridge to guide your razor saw). Cutting behind the lower ridge gives you a wide surface (a tad larger (at 41mm) than a BT-60's inner diameter (40.5mm), but could easily be sanded down) that should be good for gluing, and the neck easily slips over the Estes Motor Mount tube (#031360), and securely holds the Pro Series II F26-6FJ motor I have.

Click to expand...

I hope those are nation-wide and not local. Next time I get out I'll check my near-by Wendy's. These are even cheaper than what I usually use, a screw clamp around the outside of the MMT. Works fine for motor retention, held a 500 pound thrust Kosdon motor in place...

Since the nearest Wendy's is nearly 14 miles away (or one hour by bike, 1 1/2 hour away by bus), I explored the local fast food outlets and 7Eleven today. I found that Hershey's Chocolate Flavored Milkshake, and the milk at Burger King are made from HOPE plastic, and woud make good substitutions for the Wendy's bottles.

The Burger King's bottles appear to be an exact match for the Wendy's bottles. I found that their white milk ($1.49USD) is nonfat (YUCK!!! ). I complained about it, and was given a chocolate milk (lid is brown) which was low fat, and was the better tasting chocolate milk compared to the Hershey's Chocolate flavored Milkshake (too sweet). I think if I was to stake out a Burger King or Wendy's, I could score a number of them from people tossing their kid's milk away after finishing their meals, just by asking. The alternative idea would be to do some dumpster diving.

Hershey's bottles (found at 7Eleven's $1.79USD) are a little to tight for the Estes 29mm Motor Mount tube (031360) without sanding. After cutting mine free from the bottle, and sanding the inside for a couple of minutes, it fit the 29mm Motor tube beautifully. The Hershey's lid isn't as easy to cut as the ones from Wendy's and Burger King, but the Wendy's, McDonald's, and Burger King lids fit. I doubt you could score these often for free.

McDonald's uses bottles that have compatible lids (identical to the Wendy's and Burger King lids). However, the bottles are made from an apparently blow molded #2 Plastic (High-Density Polyethylene, aka PDHE or HDPE). IMHO they wouldn't be good for retainers, but for a D-Region Tomahawk, they may be OK for a 29mm to inner fin body centering ring (with wraps of tape to thicken the motor tube). Subway's bottle is also a #2 Plastic, but the lid is thick (has a good ring for guiding cuts), and suffers from the same problems as the McDonald's ones.

Caveat on the Milk bottle idea... It fits Estes' 29mm Motor tubes beautifully (without modifying the tube). I just checked, despite being thicker, Sunward's 29 mm motor tubes will fit the Estes 29mm Motor Retainers (without modification of the tube). If you want to use the milk bottle retainer on Sunward tubes, you may need to remove a layer or two of the paper.

What size gator aid bottle are you using?

Andrew

Found more of the 29mm compatible milk containers, and now we've got more colors of lid to choose from.

Dairygold's 32oz Chocolate Milk has a red lid (~$2.00 USD) Dairygold's 16oz Chocolate Milk has a compatible lid (black), but the bottle isn't (~$1-$1.50USD)



Lucerne's (Safeway's brand) 16 oz bottles of milk also have black lids that fit the necks of bottles that are compatible with 29mm Motor retention, but the bottles are not compatible.

Nestle's Nesquick 8 oz bottles of Chocolate Milk are too large for use.