Flis Cougar 660
 

I pulled some kits out to build over this holiday weekend. Among them is this Flis Cougar 660 . While it's not an old rocket per YORF classic standards, it is old in the sense that it's been hanging around my house for several years waiting to be built :)

I can't recall when I bought it. It mighta been the NARAM in Evansville back in 2003, or it might have been at NARCON that same year down in Austin. But I got it because of its Estes-Sprint-competition looks.

It's a very nice kit and includes a couple of really kewl extras: there's a 6" x 60" competition streamer and a very cleverly done pop lug, shown below. The included wire is to be cut and formed to hook the lug between two fins aft and a tiny hole bored in the airframe forward.


The package includes the components shown below. Besides the competition streamer, there's a more common crepe streamer for sport flying and a sheet of 1/64" birch ply for the fins along with three fin patterns. The competition streamer is the white object rolled up in the centering ring. As you can see, I chose the basic elliptical pattern. The fins are supposed to be mounted on the boat tail, but I moved them forward (and changed the root cut a little to maintain the sweep angle) to give it a more Sprint-like appearance. Furthermore, I opted to use 1/16" balsa in lieu of the competition ply.


The motor mount includes only one centering ring forward. And this is OK. I've seen competition flyers roll up vellum into egg lofter airframes and insert a motor tube and get it aligned without great difficulty. So I know it can be done. But since I'm not competing, I cut a longer motor tube and used two rings thus simplifying the motor mount build. Keep in mind, I'm re-engineering this to Doug's paradigm and not because it's in any way lacking. It is in fact a very well crafted competition bird IMO. Removing a little weight by eliminating a ring and shortening the motor tube are certainly good steps toward getting a competitive edge.

Since I opted to forgo the pop lug, I glued it in place after beveling the ends. Not sure if that really reduces drag, but it looks faster :D


Overall, the kit looks like this (below). I like that style of nosecone. Again, it gives the bird a Sprint-like appearance.


Lastly, here's a close-up of the fins. I cut them from scrap 1/16" balsa I had on hand. As you can see, there's another vendor's logo on the rocket now. Thought you'd get a kick out of seeing that. (Sorry, Jim :))



I'm looking forward to flying this. The ½A3-4T and A3-4T motors are the likely motors. I might even try it on a ¼A3-3T. I have a few A3-6T's which might work. And since I left out the motor block, I could even try one of the old A3-5m's I have.

Doug

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Great to see this Doug. I've got one still in the package also that I picked up a few years ago. Got me wondering if it's got a pop-lug in it. That looks like a great design, both rocket and pop lug.

Doug,

Looking good. Many folks who buy the Cougar 660 make their own modifications based on whether or not they are competing along with other tricks they've learned along the way.

A lot of what went into that design (probably over 25-30 years old now) I picked up from Ken Mazoi and Howard Kuhn :)

As for that *SEMROC* fin... be careful... Too many vendors built into one model can cause a rip in the space-time fabric of the universe, ya know.... LOL

Carl should get a kick out of that fin. I love it when I see something like a Big Bertha fly and watch it deploy one of our diamond parachutes LOL

If you get a chance, you should try that pop-lug. They're really cool and seem to be a lost art in the competition world.

jim

I remember my childhood friend rigging a pop lug based on an article in his NAR magazine back in the 70's. It looks very similar. We taped the tip of the launch rod to stop the lug. The lug was held on the rocket with a piece of wire stuck into a pinhole in the body, and hooked over the rear. It worked like a charm.

Outside of competition, the pop lug could be used to slick up the appearance of a scale or sport rocket. Just position the pinhole where a LOX vent should be and it could become part of the looks of the rocket. :cool: Do the scale competition guys use pop lugs, or are they more into internal launch lugs?

In my opinion, this should be marketed as a pop lug kit that includes a free rocket. The lost art of the pop lug Jim's referring to is an outstanding performance gain for very little cost and effort.

As for scale, once I built a Cougar and started using pop lugs, I never put a lug on a scale model after that (other than some simpler sport models). There are a few cases, though, where pop lugs don't work well on scale, such as funky body tube sizes (ex. Soyuz) or where there are lots of do-dads that either get in the way or could be knocked off (Saturn, Little Joe). Also, you're still putting a hole in the side of the model for the lug, albeit a small one. The best approach I've found now for avoiding lug appearance on scale is to simply go with a piston, especially now that you can also get a "starter kit". Heck, they're so cheap and simple, anyone with access to Mar/Apr 2009 Sport Rocketry can build one out of spare parts probably littering your build bench...

--Chan Stevens

The thing that I love about pop-lugs is that they are SO easy to set up and SO reliable (I've never seen one fail). The thing I HATE about pop-lugs? I'm always half way home before I realize that I left the darned thing on the launch pad... LOL

...sitting next to your clip whip :)

Doug

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Nose weight
 

Last night, I ran some sims and found my Cougar 660 to have marginal stability, less than 1 caliber with the motor loaded*. And on a long, skinny rocket, that's not very good. So I decided to add 5g of nose weight. Between that and the chute and wadding, it should be safely stable.

Here's how I did it. I drilled down about an inch with a 5/16" bit, then bent some piano wire into a U, with some barbs formed on the tips at 90°.

I mixed up some epoxy, then added 5g of bird shot and poured the slurry into the opening with the piano wire in place. This gives me some nose weight and supplants the screw eye as well.


*I also found another Rocksim error. Seems the installed weight of the A10-0T is listed wrong by ~4 grams as I recall (in the .eng file), nearly 50% in error. It should be 8.5g per the NAR spec sheet.

BTW, isn't RustOleum awesome? :D


Doug

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The marginal stability issue is not uncommon with some competition designs, with the intent of the event being to "push the envelope", as it were :) It will be interesting to see what times you get with the nose weight.

I saw a streamer duration model that was *so* marginal that it was *unstable* until it popped its lug at the tip of the rod :)

Good point, Jim. I should have mentioned that. These high performance designs, with their boat tails and unswept fins, tend to be that way. So adding some nose weight is common and to be expected.

Years ago, before I had Rocksim, when I flew my Sprint clone for the first time, I decided to add a little nose weight, just in case. Not having a suitable fender washer, I drilled a hole in a nickel, and attached it with the screw eye :)

Doug

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