LexxJet motivated Goony Build

Well, now that I've completed my massive Shrox build, and other things, I need to get back to the practice of making goonies as well.

This time, I'm making a goony inspired by the Dynastar LexxJet. It's one of the Shrox designed kits I built, and it's a really cool looking rocket plane.

For this goony, since the LexxJet has a long nose cone, I opted for a 60L type nose cone, instead of the shorter 60MS, as is used in the newer Bertha rockets. When I rocksim'd the design, it looked like I needed to add some nose weight. Since I have a mold for a 60L nose, I just cast it with 20g extra.

The body is a 6" section of BT60.

For the boat tail, I used a goony transition from my goony Saturn V project, which I made a mold for. It is based on the shorter 60MS, and has an internal diameter that takes a BT50.

Edit: after looking at the images taken from Rocksim's export utility, I see that it is drawing the CG in a place different than it does in the design. So, I'm not trusting the CG marker in these two exported images. The .RKT is showing the CG as I am expecting, at least on my PC.



View attachment LexxJet goony.rkt

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Here are the pieces I made. I've got the nose cone and transition/boat tail. There's also a 6" BT60 tube.

As an engine mount, I've got a home-made clip I use for most of my rockets, as described on my webside, under the cloning page. I've also got some scrap BT20 and BT50 tubes, along with some CR2050 and CR2060 rings to make a connection for the BT50 hole in the transition, and to connect the mount to the BT60.

The shock cord will be a stretch of kevlar fastened around the body tube, long enough to extend to the front, so I can fasten some elastic to it.

For fins, the rocket has four basic mounting points, at 0, 90, 180, and -90 degrees. The vertical stabilizer is out the top, the keel is out the bottom, and at the sides are some pods that represent jet engines.

The wings/fins are mounted on the bottom.

I marked the location of the fins using my fin guides, and used one of my tube marking guides for drawing the lines for aligning the stabilizers and pods.

Here, I'm fastening the basswood piece to the jet-engine pod. The basswood piece is 1/16", since that's what I opted for for this rocket, since I like basswood, and didn't want too much weight in the rear of this rocket.

The piece is sculpted with my laser cutter to fit just right against the boattail. I found on this project that rocksim has the ability to export 2D images, so I used that to get .SVG images of the fins. This means that I can go almost directly from rocksim, to my laser cutter, with just a small hop through an SVG editer to rescale the image and send it to the laser. I wish I knew this back on the Shrox project.

Two of these pieces were made from 1" BT20 tubes. Both had bevelled BT5's, 2" long, inserted later, to follow the styling of the Lexxjet's jet engines.

Here I'm attaching the vertical stabilizer and the keel.

The keel extended from the boat tail to the body tube, so I fastened it first. This way, the fin guide was secure on the body tube while the keel dried. I also applied a small bit of epoxy to hold the keel on the polyurethane boat tail.

Then, when the glues had dried, I needed to keep the vertical stabilizer plumb to the keel. The complication is that I don't have fin guide that would fit the boat tail, and the vertical stabilizer doesn't extend over the body tube. So, I cheated a bit, and tipped the fin guide to an angle. This way, the keel kept the guide aligned, and the guide could straddle the stabilizer enough to keep it in place.

The stabilizer was likewise held in place with a small amount of epoxy,.

After the keel and the stabilizzzer dried, I fastened the two jet engine pods where I had marked the 90 and -90 degree lines. I relied on old school techniques to get these parts in place - I eyeballed them. And by old school, I mean my eyes aren't all that good. So if there are any flaws in the placement of these parts, squint, and it will look as good to you as it does to me.

The wings were also applied, by gluing them onto the bottom. They are also 1/16" balsa. I held them in place with my T-mount, so they would be perfectly plumb to the keel. Just to be totally sure, I did put a small amount of weight on the wings, just to hold them against the mount, but I hadn't done that by the time I took this picture.

From this rear-end view, you can see how the BT20 tube for the engine mount is centered in a BT50, which is glued into the Goony T5060 transition I made.

From here, I mounted the horizontal wings atop the vertical stabilizer, and mounted the tips on the end of the wings.

I also mounted a 2" section of launch lug up against a wing. Don't forget the launch lug - I just about did, in my eagerness to start the finish.

To finish the rocket, I primed it with Rustoleum primer. I thought I grabbed one of my cans auto filler primer, but it was merely auto primer. Not filler. So I went ahead anyway, and just applied a few coats of the black primer. I sanded with 220 grit after the 2nd and 4th coat, and after the final coat, which may have been 1 or two more - I forget.

It looks kind of stealty at this point. Kind of like what someone from blackwater might fly. Or Hugh Hefner.

This is after I painted it with three coats of Rustoleum gloss white.

I still need to make the decals and apply some detail paints, but since this is now April, the taxman raised his ugly head and is distracting me for a bit.

Edit: an astute observer might notice that the wing tips changed between priming and painting. After I primed the rocket, I was looking at the decals on the LexxJet, and realized that I put a taper into the wing tips. But, the Lexxjet was supposed to have a flat back end on the wing tips. So, I whacked off the offending members, rectifying the situation.

D'oh! I also just now observed that the wing placement didn't match the rocksim. In the rocksim, I had them mounted 1" further toward the rear. But, in the real world, I forgot that, and mounted the wings flush to the end of the body tube. I just double-checked with rocksim, and I think I have enough a safety margin that it will still be stable. But, I'll make sure to use a B engine first, just to reduce the rear-end mass.

Excellent!

These guys have a couple shots https://www.airliners.net/photo/Unt...1010915/&sid=59af2bc85327fdfd20a44932c4944f0a

Interesting following the unintentional design changes and how to adapt and thrive. Nice looking bird, sure like the idea.

WOW Thats cool!

NICE!!

I like those fin alignment guides...

Where do you get those at and what sizes do they come in??

AfterBurners said:

I like those fin alignment guides...

Where do you get those at and what sizes do they come in??

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Well, trying to avoid making too obvious of a plug, but they are available at my web site, listed below. They are available for most BT-sized tubes, for 1/16", 3/32", and 1/8" fins.

I have to admit, they really did help me succeed at a huge build I did recently - here

Wow that looks awesome! That could be sold as a kit.

DAllen said:

Wow that looks awesome! That could be sold as a kit.

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Thanks for the compliment. For this design, I think the credit goes to the guys at Dynastar, and to Shrox, for making such an attractive design to start with. I'm just the transmogrifier on this goony.

This is a good thread, but I would laso like to here about your Saturn V goony maybe in another thread.
Do you have any pictures of the Saturn V goony you could share?

Hi Saluki,
The pictures of Saturn V and Saturn 1B goonies I made were posted here: https://www.rocketryforum.com/showthread.php?29022-Goony-Gallery&p=259334#post259334

Now for some painting.

I painted the nose a Rustoleum Apple Red. That was pretty close to the color that my laser printer makes red, so I painted the nose, and used a decal on the tail. The Lexxjet uses a bevelled paint scheme, so to get the beveled scheme for the red, I cut the bevel in wide blue tape on the laser cutter. Then, I masked off the rest of the rocket, and painted the nose.

While the paint was drying, I prepared the decals. These were made on transparent laser-printer decal sheets. These were based on the decals I made for the full-sized LexxJet that I built at the end of last year. Most of them were redrawn from the LexxJet decals, instead of simply scan of those decals.

Now, I just need to pick a parachute, and wait for this damnable rain to pass the Northwest into some other part of the states so I can launch - where, I don't care. Just somewhere else.

That is Very Cool!

That is attractive.
And sure brings to mind one of these from Iberia https://www.airliners.net/photo/Iberia/McDonnell-Douglas-MD-87/1200265/&sid=ada9a06f6d7ad4a3251bba7c0c408717

Did it fly? How much stinkin' nose weight was needed?

Daddyisabar said:

Did it fly? How much stinkin' nose weight was needed?

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It's in the OP...

DavidQ said:

... Since I have a mold for a 60L nose, I just cast it with 20g extra.

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If that is what the computer said I am good with that. Don't really need to fly it then.

What a beautiful job you did on this! I have the Lexxjet in my build pile and this thread definitely motivates me to get at it, but I have another one in front of it.

DavidQ said:

While the paint was drying, I prepared the decals. These were made on transparent laser-printer decal sheets. These were based on the decals I made for the full-sized LexxJet that I built at the end of last year. Most of them were redrawn from the LexxJet decals, instead of simply scan of those decals.

Now, I just need to pick a parachute, and wait for this damnable rain to pass the Northwest into some other part of the states so I can launch - where, I don't care. Just somewhere else.

Click to expand...

Now THAT is cool. Everything the Estes Jetliner should have been.