Finally got to build the Satellite Killer - Fun Kit!

[markschnell]

I've been wanting to build the Satellite Killer from Semroc for years now. It's one of their Retro Repros, this one being a clone from Centuri along with the Red Eye Satellite that could be bought with it in their "War in Space" combo back in the early 80's.

It's a bit on the pricey side ($34.99 from eRockets.com) but I was glad to get this from my Secret Santa. It's a straightforward build but lots of fun. I used white glue, but if you used CA and accelerator you could build it in a few hours. I need to seal the edges with thin CA, sand a bit and then wait for a good day to paint. As with all the Semroc kits, the laser cut parts are done very well.

It's a lot bigger than I imagined. I love these old school, oddroc type kits.

 

[markschnell]

I noticed after the fact that I glued the five legs on too high. The parts with the dowels sticking out should actually be below the main body tube. Doesn't change the look much, I'm not worried about that, I just hope that's not an issue with stability at launch. I'm hoping this kind of body shape won't matter much for that.

 

[kuririn]

I just hope that's not an issue with stability at launch

Don't think you have to worry, stability is mostly from base drag.
The fiber legs though, are prone to bending and creasing on landing, even with the dowels.
Especially with those big paddle fins.
Perhaps painting with some thin CA at the weak points might help.

 

[markschnell]

I'm wondering if the Semroc kit improved the design a bit. The pic you show has the dowel stopping short of the triangular crosspiece. The instructions call for the dowel to go all the way to the panel piece now. I made sure to reinforce that with extra glue fillets. I hope it'll stand up to launches. I love this kit.

 

[markschnell]

Don't think you have to worry, stability is mostly from base drag.

I was hoping someone would tell me that, and I thought it might be you. From the stuff you post on here I think you and I have overlapping styles that we like in rockets.

 

[markschnell]

@kuririn I looked at the instructions again and the tab that is right in front of the break in the leg is supposed to be snapped off in the current kit in step 18. It even has laser cut perforations that allow the part to snap off cleanly. That allows the dowel to go all the way to the panel piece. In your photo I don't see the perforation.

 

[kuririn]

Ah, I see. You are correct Mark.
My build was a clone, not a kit.
I purchased only the laser cut fiberboard legs and fins and the cardstock antennae from erockets.
Rest of the parts came from my stash. Like you, I thought the kit was kind of expensive.
Removed the 18mm motor mount and lengthened the BT-50 tube so that the parachute was fully enclosed.
Glued in a 24mm thrust ring.
IMHO it needs 24mm power to get any decent height.
And it needs as short of a delay as possible.
Erockets still has the fiber fins, so I think I'll rebuild mine the right way.

 

[MALBAR 70]

I love mine and have flown it quite a few times, it's a gretat flier on C5-3's. Kuririn is correct the fiber board legs will kink even with the dowel going all the way to the solar panel.

 

[neil_w]

Why do they use fiberboard for that? I'd think glue-papered wood would be a better choice, given that it is totally unsupported. I'd probably choose basswood if it didn't make the whole thing too heavy, but then again fiber board isn't too light either.

Then again maybe fiberboard is just as strong as papered basswood, who knows. But that wouldn't be my guess.

 

[markschnell]

I'm looking forward to trying mine on a Quest D-16-4.

 

[markschnell]

Why do they use fiberboard for that? I'd think glue-papered wood would be a better choice, given that it is totally unsupported. I'd probably choose basswood if it didn't make the whole thing too heavy, but then again fiber board isn't too light either.

Then again maybe fiberboard is just as strong as papered basswood, who knows. But that wouldn't be my guess.

I would think balsa would be stronger than fiberboard and lighter, especially if you used the dowels on the bottoms of the wings. Of course, if you put the holes in the wings to save weight maybe not. I'm sure someone will cut out a balsa one and compare them. ;-) I'd do it but my scales aren't sensitive enough.

 

[neil_w]

I'm looking forward to trying mine on a Quest D-16-4.

I'd be concerned it would fire the ejection charge on or close to the ground, although I'm not really sure. Be careful.

 

[markschnell]

I'd be concerned it would fire the ejection charge on or close to the ground, although I'm not really sure. Be careful.

You think that would go lower than a C motor that it calls for? I've had great luck with the Quest D motors.

 

[kuririn]

I'd be concerned it would fire the ejection charge on or close to the ground, although I'm not really sure. Be careful.

Yes, absolutely true. Both flights I had were nailbiters.
Chutes ejected too close to the ground, not enough time to fully deploy.
E12 motors IIRC.
That's why I mentioned as short of a delay as possible.

 

[GlenP]

Looks like the Red Eye has the metallic foil stickers like the original, but I was a little surprised and disappointed that the SEMROC RetroRepro Satellite Killer kit stickers were not metallic foil like the original. It still is a great kit and otherwise looks just like the original. The only reason I bought the kit rather than cloned it myself was the hope of the metallic stickers, I mean I can print my own stickers at home on label paper. But, I guess you gotta compromise somewhere to kit one of these. You might be able to get a little more reflective sheen by going over the model with a glossy clear when done. With the rear-eject engine mount and the chute loosely packed in one of the tubes, it opens up pretty quick on a C6-3.

 

[kuririn]

Ah, rear eject!
I modded mine to 24mm motor mount permanently glued in. (Actually just a thrust ring.)
And traditional chute eject off the central motor tube.
After reviewing the instructions I see it's motor mount rear eject with the chute and shock cord held in place in one of the outer tubes by a Tyvek strip. I guess the bigger outer tube will make a difference in chute deployment.
Or maybe I should replace the E12 with a composite?
Anyhoo, parts are on the way for a replacement.
Maybe I'll go 24mm and motor kick out with the Tyvek holding in the chute and shock cord in an outer tube.
We'll see.

 

[kuririn]

Better idea:
1/4" wide BT-50 sleeve with a loop of kevlar string attached.
Slip the sleeve over the end of the 24mm motor prior to launch and tape down.
At ejection motor kicks out and pulls the kevlar string and shock cord/chute out of the outer tube, but stays attached. No motor casings falling from the sky.
BTW I was surprised to see that the double slit method of attaching the shock cord to the outer tube was used.
Last time I used that was when I was a 13 year old kid. So stone age.

 

[BABAR]

Looks like a good mod would be adding some carbon fiber strips or rods to reinforce the legs.

 

[markschnell]

Better idea:
1/4" wide BT-50 sleeve with a loop of kevlar string attached.
Slip the sleeve over the end of the 24mm motor prior to launch and tape down.
At ejection motor kicks out and pulls the kevlar string and shock cord/chute out of the outer tube, but stays attached. No motor casings falling from the sky.
BTW I was surprised to see that the double slit method of attaching the shock cord to the outer tube was used.
Last time I used that was when I was a 13 year old kid. So stone age.

That's an interesting idea for using a 24 motor.

I know this model first was offered in the Centuri 1981 catalog, but even then the slit method would be old-school. I suppose Semroc was trying to keep the kit as retro as possible. The instructions talk about heavy forces from the ejection charges but they wouldn't be any heavier than what any other rocket gets, right? The tri-fold method would work and there's plenty of room in the tube to use it.