Building a FlisKits Cheetah!

[cmmeyers]

As promised, I'm documenting my build process of the FlisKits Cheetah! that I won in the FlisKits birthday giveaway contest.

Here's the obligatory picture of the unopened package. It’s always exciting to try to check out the contents before you open everything. As usual, FlisKits packaging is top notch!

 

[cmmeyers]

Here is a picture of the two motor mounts (remember that this is a two stage rocket). Notice the one motor mount for the sustainer section has grooves in the centering rings. They are for the Kevlar thread that will be connected to the motor mount.

 

[cmmeyers]

The booster stage with the motor mount installed. (I should have put something next to these pictures for scale)

 

[cmmeyers]

Here are the 8 fins that have been cut and initially sanded. FlisKits provide 2 sheets of balsa for the fins. But if you layout the templates carefully, you can get all 8 fins from one sheet of the stock. That leaves more for errors or later projects. Thanks Jim!

 

[cmmeyers]

Here is a closer view of the fins after the initial sanding showing the fin edges tapered. Fill-n-finish has not been applied to the fins yet. I do that before attaching the fins to the rocket. The balsa included in this kit seemed very soft and sanded very easily. If you wait to apply fill-n-finish until after you attach the fins to the rocket, chances are you might snap a fin if you aren’t careful.

 

[cmmeyers]

A picture of the booster and sustainer tubes with the motor mounts installed. (again, nothing to show scale, but keep in mind that the rocket is nearly 24” long). Notice the Kevlar thread that comes out of the body tube at the top of the motor mount. This is so the rocket falls nearly horizontal rather than coming down fins first. An interesting idea, and I can’t wait to see it in action.

 

[cmmeyers]

(Here’s where my brain started to go south.)

This is a picture of the fins glued on the sustainer. I even remembered to make sure that the fins were glued correctly, making sure that the leading edge had the grain properly positioned (you can’t tell from this picture, but it was correct). It’s starting to look like a rocket!

 

[cmmeyers]

Here is a top view of the fins on the sustainer. Lined up perfectly and looking good! (I thought)

 

[cmmeyers]

Brain still heading south. (Paying too much attention to “The Apprentice”, and not enough on what I’m actually doing)
Here is a top view of all of the fins attached to the booster and sustainer. They are lined up perfectly from a tail-end view. Again, I made sure that the grain was running correctly on the leading edge of the booster fins.

 

[cmmeyers]

Another pic of all 8 fins glued onto the rocket. It’s almost ready for fillets!
Looking good, right? Wrong!

 

[cmmeyers]

Now is about the time I realize my error….right after I applied the fillets. You may have picked up on it, but it may have been hard to tell from the pictures.
I glued the booster fins on the sustainer, and the sustainer fins on the booster! Ugh!

Sooooo……. Here is a picture of where I stand right now. I was able to remove the fins fairly easily since the glue wasn't fully dried. I have to sand down the body tubes where the fins were glued and began to set. I should be able to sand the fins too. If I can’t fix the fins with sanding, I always have that extra piece of finstock that I didn’t use earlier (thanks, Jim!). I feel stupid, but at least it was a repairable error. At least the glue wasn’t completely dried yet, and it didn’t do too much damage (if any) to the body tubes. I’ll keep you posted with my progress.

 

[jflis]

DUDE! I done that, man! LOL

*twice*!

So don't feel too bad

Great assembly photo essay by the way.

I have one *Cheetah!* single stage model (after gluing the booster fins on the sustainer and let them dry before discovering the problem i just left it)...

I have another one with the fins reversed so I just added enough nose weight to make it stable again LOL

Another point, about the Kevlar. There are two reasons that I have the cord installed with it exiting the body wall at that point. One you pointed out, so that the model comes down a tad sideways. This is more to create more drag to help slow the model rather than to keep it from coming down "fins first". But also, this keeps any sort of shock cord mount *out* of the body tube so that there is no obstruction for the recovery device.

keep us posted!
jim

 

[Localx]

Oh please, I was building my replacement Viking this past weekend and after sliding in the motor stop I decided to mount the fins on the other end of the tube opposite the motor. I'm keeping it to show the little ones what a mistake you can make when not concentrating. I've also walked out to the pad so excited I've forgotten the motor. We all have those days. (I hope)

 

[JRThro]

Originally posted by LocalX
I've also walked out to the pad so excited I've forgotten the motor. We all have those days. (I hope)

Just this past weekend, I had a rocket on the pad before I realized there was no igniter in the motor. The only thing that tipped me off was that there was no place to hook up the igniter clips.

 

[jflis]

You haven't lived embarassment until you've walked out to the assigned pad only to realize you left you MODEL at the RSO table...

sheesh!

 

[cls]

...mount the fins on the other end of the tube opposite the motor.

keep it for a stability demonstrator. today I did a demo launch for my son's 2nd grade class. before we launched I balanced a rocket on string and held it in front of a fan to show the correction from the fins. the fan's breeze was a bit turbulent and spirally but they got the point. I wished I had a "backwards" rocket to show what happens with poor stability.



by the way, Cheetah is an excellent flier. the upper stage will go nearly out of sight on B6-0 -> B6-6 combination. we're too scared to try it on C motors!

for a while the upper stage was flying squirrelly. turns out the "CHEETAH" sticker was peeling and catching air, so we removed it and now the rocket flies just GREAT!

 

[BobH48]

Originally posted by JRThro
Just this past weekend, I had a rocket on the pad before I realized there was no igniter in the motor. The only thing that tipped me off was that there was no place to hook up the igniter clips.

Does this sound familiar?

You set your rocket on the pad, hook it up, ..5..4..3..2..1.. ignitor burns but no liftoff.

You go back put another ignitor in and same thing happens.

You go back again and realise..... Gee, this motor has already been used.

NO WONDER IT DIDN'T LIGHT

 

[rocketdad0934]

by the way, Cheetah is an excellent flier. the upper stage will go nearly out of sight on B6-0 -> B6-6 combination. we're too scared to try it on C motors!



don't be scared we flew mine on c's for its maiden voyage it was gone, one of the best shows Ive seen we did find the bird, we saafely estimate it at a mile from the launch pad. It would have been lost forever or at least until the last cmass launch if it weren't for the flea that went on the same trajectory and a good pair of binoculars. the last time the cheetah went the booster stayed with the sustainer, it did kick the motor so I got it back all burnt up. lucky me Jim had the parts on hand to rebuild it and now it sits waiting for the rain to stop so it can be painted

 

[BobH48]

This is a nice thread. Good job on the build so far.

I bought a Cheetah at the Anniversary Party launch but haven't got around to building it yet.

I'll have to pay attention when putting the fins on!

I won't have time to build it before next weekends CMASS launch, but maybe by the next one.

 

[cmmeyers]

OK. I finished the build this weekend. I put the fins on correctly this time!

 

[cmmeyers]

It is almost ready for paint. I need to do some final sanding to make sure all the fillets are smooth.

Question : how do I paint this thing with the Kevlar thread protruding from the body tube? I can't tuck it back in the tube. I'm thinking of rolling it up tightly and wrapping it in tape. Any other suggestions?

 

[cmmeyers]

Here is the paint scheme that I've dreamed up for this bird.

If you are unfamiliar with VeggieTales, this will be foreign to you. LarryBoy is a superhero. His helmet has "super-suction ears". He drives the LarryMobile which is a car that can turn into an airplane (among other things). My sons have LarryBoy on the brain, and I told them that I would paint this rocket in a LarryBoy/LarryMobile theme. It's going to take a good bit of masking, but it shouldn't be too terribly difficult.

 

[JRThro]

Originally posted by cmmeyers
Here is the paint scheme that I've dreamed up for this bird.

If you are unfamiliar with VeggieTales, this will be foreign to you. LarryBoy is a superhero. His helmet has "super-suction ears". He drives the LarryMobile which is a car that can turn into an airplane (among other things). My sons have LarryBoy on the brain, and I told them that I would paint this rocket in a LarryBoy/LarryMobile theme. It's going to take a good bit of masking, but it shouldn't be too terribly difficult.

Cool paint scheme!

Will you be adding any Larry Boy stickers/decals?


------------------------------------------------
(These lyrics copyright Big Idea Producations, yada, yada, yada...)

Song Lyrics: Larry-Boy Theme Song

Larry-Boy! Larry-Boy!
Lean and mean green machine!
Larry-Boy! Larry-Boy!
Out of sight, veg-o-mite!
Larry-Boy!

Who do they call when Bumblyburg's in trouble?
Who's got the suit with super-suction ears?
There's no need to panic, 'cause this guy is manic,
And you know that he'll save the day!
You need a hand, he's right there on the double
Hey, hey, he's on the way
Purple and yellow! He's one super fellow!

Larry-Boy! Larry-Boy!
Lean and mean green machine!
Larry-Boy! Larry-Boy!
Out of sight, veg-o-mite!
Larry-Boy!

Where do you turn when this world needs a hero?
A man with style and plungers on his head?
It's easy to prove he's just one of the grooviest
Cats that you'll ever know.
It's plain to see in fashion he's no zero
At the wheel of the Larry-mobile,
Purple and yellow! He's one super fellow!

Larry-Boy! Larry-Boy!
Lean and mean green machine!
Larry-Boy! Larry-Boy!
Out of sight, veg-o-mite!
Larry-Boy!

Long may the voice of freedom reign!

I am that hero!

Larry-Boy! Larry-Boy!
Lean and mean green machine!
Larry-Boy! Larry-Boy!
Out of sight, veg-o-mite!
Larry-Boy!

Larry-Boy! Larry-Boy!
Lookin' great! Fashion plate!
Larry-Boy! Larry-Boy!
Lean and mean green machine!
Larry-Boy! Larry-Boy!
Out of sight, veg-o-mite!
Larry-Boy! Larry-Boy!

Lean and mean green machine!
Lookin' great! Fashion plate!
Out of sight...

Dynomite!

Larry-Boy!
------------------------------------------------

 

[cmmeyers]

Originally posted by JRThro
Cool paint scheme!

Will you be adding any Larry Boy stickers/decals?

Possibly. The kids will probably want to. The purist in me says, "the LarryMobile doesn't have stickers, so the rocket shouldn't". But we'll see!

 

[cls]

my son decided to wrap the kevlar in tape before painting - that worked perfectly.

he picked a "rainbow" paint job: red nose cone, orange at the top of the sustainer airframe, yellow below that, then green, then blue, then purple; the booster section was purple and silver. there's a picture of it posted somewhere here on TRF.... ah, here
it is in this thread.

 

[jflis]

Originally posted by cmmeyers
It is almost ready for paint. I need to do some final sanding to make sure all the fillets are smooth.

Question : how do I paint this thing with the Kevlar thread protruding from the body tube? I can't tuck it back in the tube. I'm thinking of rolling it up tightly and wrapping it in tape. Any other suggestions?

You can tape it, as some have done, or just paint over it, as I often do At least that way the cord blends into the body color better...

 

[rocketdad0934]

I taped mine in place so it didin't jump around while I painted it to match the rocket kinda like camoflouge. I tried to get the picture of it moved from fliskits web sight to here but I don't know how so if you want to see it check the cmass photos of oct 2 @ fliskits.com. I don't know what happened to my face but its a good picture of the rocket.

 

[jflis]

Bill, are you talking about this picture?
https://fliskits.com/photo_album/cmass_100204/images/p1010153.jpg

 

[rocketdad0934]

yes, thank you Jim

 

[vjp]

Isn't the shock cord supposed to go on the INSIDE of the rocket?

Or is it supposed to suspend sideways during recovery? (like the Saturn V's upper section).