1/2 Scale Patriot

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Jan 23, 2009
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I am building a 1/2 scale Patriot from PML. I am converting it to DD. My approch is a basic DD set up but if any one has done this or has a build thread to link I would appreciate it. I have a L2 cert and have built and flown DD before but I always ask for tips because of that "Man I wish I had thought of that " reason. Also, like someone has asked on MPR about a color scheme, I have seen pics where there is no yellow and the fins are more brown then red. Can't find a GOOD pic to copy. Any help would be appreciated.
There are some pretty decent photos especially in the first link:



I built the PML 1/4 scale version, and also set it up for DD using a standard coupler ebay. For the 4" version, I had to extend the payload 6" to get everything to fit without going into the nose cone.

A suggestion is to give Tim at Wildman a call, and get some 1" stap kevlar, and epoxy that to the motor tube instead of the piston strap, if you use the piston(s) at all. I used pistons for both drogue & main, and like them well enough - though some don't. You have to clean up after the ejection charge carefully though, or next time they can bind. If you use the kevlar strap it can be tied to your tubular nylon outside the tubes. Even better is to glue both ends of the kevlar strap to the motor tube, and send a loop out the top of the tube to tie your nylon to. That way if one of the straps break, the other is still there - I think I got that tip from Tim or maybe Jim Hendrickson. For other places like the ebay and NC that you can reach easily, I like to use quick links instead of gluing the strap on. Makes it easier to take apart for clean up and transporting. My $0.02 if it helps....

I assume you will you glass the tubes? My 4" version is quantum tubing so couldn't. Still flies great on 38mm J's though....
Thanks for the pics
I was trying to stay away from glassing. Haven't tried that yet. Not planing on using more than a K motor, But......... Can this hold up without glassing.
I also built the 1/4 scale Patriot and converted it for DD. I built a removable ebay and fitted it with CD3, flew it without drouge for my level 1 on an I285, only had to walk twenty feet to recover it. Really pleased with it and going to try different engines whilst building my L2 rocket.
Thanks for the pics
I was trying to stay away from glassing. Haven't tried that yet. Not planing on using more than a K motor, But......... Can this hold up without glassing.

I'd be surprised if it could not hold up to most J & K motors. Glassing though would protect the tubes from cracking due to a rough landing or things getting slammed around upon ejection.
I HIGHLY recommend 2 wraps of 6oz glass on the tubes. PML tubes are phenolic and will chip or crack very easy. My first big rocket was an Ultimate endeavor [6in tubes]. I built it stock, lasted 6 flights before tubes finally had enough. The only thing I would have done different was glass them.
It is on it's 3rd rebuild, they are now glassed. 2nd time, blew a hole in the tube from ejection charge. 3rd time landed rough and knocked another hunk off the top. Every flight resulted in more and more hairline fractures, and I was even using a Skyangle Cert3 X large, rated for 35-70lbs. The rocket only weighed 28lbs. But it's all in the fincan! No problem with flying, always the landings, and I fly on sod.
Repaired them past their usefulness.
First time was due to just the fincan falling over in the living room, chipping a large hunk out of the top. It was on carpet!
Phenolic has great strength in compression, but not so much in hoop. It will shatter.
A shame to go to all that work to build, when just a little more, by glassing, will extend it's life expectancy several fold!

Just put your E-bay in the coupler and hold it on the payload with plastic rivets.

I used my piston as a sliding zipperless device by drilling several holes[to release pressure] in the plate,and putting a stop on it so upon ejection it would stop at the top of fincan, only protruding about an inch. This was done to help reinforce the tube upon landing. I have kept this design part of the rebuild.

I would also recommend adding some 2 part foam to the NC. You don't have to fill it, just about half will do, greatly adds to longevity, without much weight. I foam all my glass NC's for this reason.

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Blackjack, can you explain using the piston a little more. Do you run a shockcord from the MM to the piston to stop it from coming out? A link to glassing would help. And pics always good.
Sorry no pic, the rockets in Chicago getting painted, and I'm in Savannah. But I drew how it's done, several others have seen this in action and adopted it successfully to their own applications.

Simplicity at it's best. Just a loop of TN from 2 eyebolts in top CR, that passes through the slit in piston BP. Then position the piston about an 1in. sticking out of tube.

Tie a loop in the Y-harness to keep the piston from coming out any further. The knot acts as a stop, and the loop your attachment point for recovery shock cord. The knot can be un-done and piston removed for access or repair. You can see how having the piston and BP at the mouth of the tube, greatly enhances the strength at time of impact and makes for zipperless fincan!

As far as glassing, I find the larger the tube, the easier it is. Only took me an hour to do both. Did 2 wraps at once. Helps to have an extra set of hands. One to hold the glass, while the other coats the tube and wraps it. Don't worry about seam overlap, a palm sander or orbital will smooth it even quite easily. Don't have any links, but I'm sure some others will provide some.

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Oopps! after reviewing my post, realized I forgot a important feature!

Must tie a knot on inside of BP also to aid in pulling the piston out. Sorry. Requires a little trial and error fitting,but no biggie, just don't snug up on the knot till it's positioned correctly.

I used a piece of masking tape wrapped around the TN as a guide, then removed the piston and tied my knot. You really don't need another one on the outside. I just did it as a preventive measure, making sure everything stays in place.

To use: just push piston to top of CR, load your shock cord and drogue on top, insert alt-bay and your ready to go. Nothing out of the ordinary need be done. Another bonus is the piston can be a very sloppy fit, and it won't matter. Had I NOT used this method, I'm sure my rocket would never have survived as long as it did unglassed.

Couple of pics showing the damage from falling over in the living room. I just took another section of body tube slit it and put it over the outside of the airframe. Then glass patched the hole from the inside.
At this point I didn't care what it looked like, I just wanted to fly it!

But you can see even with both thickness the tubes still got chipped through on another incident [small one in front]
When a rocket gets this big, it really needs some glass to protect all your hard work. I learned the hard way....took me till the 3rd time to figure it out.
Don't hesitate to ask anything else on your mind.



Is it getting painted by a freind or a business? I have a Talon that I need to find out how to make pretty.

Sorry for bringing this off topic.

That's OK, my sister does graphics on rockets. She is restoring them, now that I have glassed and rebuilt it. I paint 'em she does the artwork. She must be doing it right, because all 3 she's done have graced the covers of various mags.




Automatic Photo Feeder0029.jpg

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I will recommend glassing tubes. I just did my first set of 4" LOC tubes and the glassing turned out to be much easier then I expected. It's really pretty easy. The hard part is figureing out what and how to fill in the weave to get a smooth paint.
Thanks everyone, Blackjack, thats a cool idea. Well back to the garage. This is why I always check on others ideas.
O.K. I've been asking freinds about glassing. A buddy at work showed me some different resins, "West System" Epoxy and "Evercoat" Premium Polyester. Any advantages to either one. He also gave me a sheet of cloth, he wasn't sure what oz. it was. I test wraped it around the body and to double wrap it, it comes up short about one inch. I checked with a local marine shop and the sheets he had he said were 6 oz. but seemed much thiner. If the sheet my buddy gave me is of a hevier cloth, would one wrap be enough?? and is there anyway to tell what thickness it is ??
My advice, stay away from the polyester resin. It stinks and is not nearly as strong or easy to work with as the epoxy.

I've done some glassing, but just glassed my first rocket so I'm not an expert by any stretch of the imagination, but from my experience with mine, I would go with two layers of lighter cloth before one layer of the heavier. I'll defer to the experts on that one.

The oz. measure of the cloth is ounces per square yard. To determine what you have, measure the size, determine what fraction of a square yard it is. Weigh the cloth and multiply the weight in ounces by the inverse of the fraction. i.e. if the cloth is 2 ft x 3 ft 2/3 of a square yard and it weights 6 ounces, multiply 6 x 3/2 = 18/2 = 9 oz per square yard cloth.
1- Use epoxy, avoid polyester- and get a good laminating type - West is a well known good one, but its not cheap. there are less expensive ones also just as good.
2- get cloth that has the right coating for epoxy- fiberglass is made with a special finish that allows the epoxy OR polyester to absorb into it (ok sometimes it works with both, but not always)
3- the type of cloth is just as important - use 8-harness satin if you can get it, or 4HS is almost as good.
4- practice on some spare tubing and make sure you get a satisfactory result before you try it on the good airframe tubing - it usually takes a couple of tries at first to do a good job.

There's lots of other good tips and tutorials out there keep reading around until you feel 100% confident you know what you're about to do before you try it....
good luck, and let us know how it goes!