11.5" Squat L3 Build Thread

[edwinshap1]

Hi Everybody,

The time is fast approaching when I will be L3 certified. I will be going through NAR and my rocket will be an 11.5" Squat.

It will feature a central 98mm MMT with three outboard 38s and three outboard 54s for future use (maybe?)

It will certify on an M1297 bought from Red Arrow Hobbies.

I will start work on the body very soon, but the MMT structure and fins will not happen until my professor gets back to me about the router table at my school.

So, without further a do, the box is just...big.

The second image is the tube and NC together.

The nosecone and tube are PML Fiberglass/Phenolic respective. My first job will be to glass the tube, then cut fin slots, nosecone attachment, and then it will be a wait until I can get some cutting time.

[patelldp]

May I suggest slotting the tube first, and then reinforcing? It will make the cutting of the slots MUCH easier.

Hope you have plenty of lead shot. That is A LOT of weight in the tail.

[awseiger]

The nosecone is bigger than the body tube! Talk about a short, Fat rocket!

[edwinshap1]

Looking at between 10-15 lb depending on exact building weights. And if I slot first, won't the epoxy and such drip through the slots and require more cleanup? I'm going to be using a cut off wheel to cut the slots, so I don't think a little glass and epoxy will do too much. I know the smoke can be pretty toxic though, I'll have to think on it.

The nosecone is bigger than the body tube! Talk about a short, Fat rocket!

That's the beauty of it

[cwbullet]

do you have a rocksim picture?

[troj]

Looking at between 10-15 lb depending on exact building weights. And if I slot first, won't the epoxy and such drip through the slots and require more cleanup? I'm going to be using a cut off wheel to cut the slots, so I don't think a little glass and epoxy will do too much. I know the smoke can be pretty toxic though, I'll have to think on it.

Pros and cons both ways.

If you slot first, then you have to support the tube while you fiberglass, or it could shrink in a bit at that point, which causes grief.

If you slot after, you have a bit more work to do cutting.

Either way is no big deal -- just pick your poison. I've done both, and find it easier to slot after.

-Kevin

[Pantherjon]

I found it easier to slot prior to glassing.And then cut the cloth when it gets to the 'leather' stage.Just be cognizant of where the slots are when applying the resin..So..I guess flip a coin!LOL

[cwbullet]

I found it easier to slot prior to glassing.And then cut the cloth when it gets to the 'leather' stage.Just be cognizant of where the slots are when applying the resin..So..I guess flip a coin!LOL

I have done both, but agree, t can be very difficult to do after glassing.

[butalane]

I've always used a scroll saw for the task and glassing before slotting is 100x easier.

Cool build. Why did you decide 3x38 and 3x 54 instead of 6x54? Is that a fitment issue?

[edwinshap1]

Different options, I have the space to fit 75s, but having more options for "cheaper" airstarts is my main idea. I would rather have the tubes in place instead of having to find three adapters.

I've never even built a rocket that has space for airstarts before, so I figured why not build it into the rocket I intend to cert on.

[UPscaler]

oh you California kids and your Squats...



Braden

[daveyfire]

oh you California kids and your Squats...

Oatz 'n squatz, bro.

[karlbaum]

May I suggest slotting the tube first, and then reinforcing? It will make the cutting of the slots MUCH easier.

Hope you have plenty of lead shot. That is A LOT of weight in the tail.

cutting slots is easier after glassing. I use an angle grinder with a zip cutting blade.

[butalane]

Oatz 'n squatz, bro.

x1000 ....

Yaaaaaahhhhhhhh Buddddyyyyy!

[UncleVanya]

Depends on the slots. If they go from the end to the front of the fin tabs then cutting first might be an issue since the tube would no longer hold shape. If they are like manufacturer provided slots (only the length of the fin tabs, not extended to the end of the tube) then the tube would hold shape and be reasonable to glass after cutting.

[CarVac]

Theoretically you could simply avoid fin slots entirely by using clever fin attachment methods. In lieu of large solid fillets, you could lay strips of G10 diagonally along the root of the fin and fiberglass them down, mimicking a large radius fillet without the weight.

Also, @upscaler: I like squats because they become more stable the bigger the motor you put in rather than less stable.

[cwbullet]

On a build that big, I would do fin slots and strong fillets.

[edwinshap1]

The slots will be 3.5 or so inches deep, so I would not be willing to surface mount a fin this large and heavy.

Below is an image of all the parts I will be CNCing within the next week.

[AHansom]

The slots will be 3.5 or so inches deep, so I would not be willing to surface mount a fin this large and heavy.

Below is an image of all the parts I will be CNCing within the next week.

Looks nice. Have you thought about running the grain parallel to the leading edge? I think it would result in less flexing along the span.

[CarVac]

It's probably plywood, so the plies run perpendicular and it's pretty much effectively isotropic.

But man, those fins will be heavy...

[AHansom]

It's probably plywood, so the plies run perpendicular and it's pretty much effectively isotropic.

But man, those fins will be heavy...

Im just a carpenter so I'm not sure about isotropics but if you make a shelf out of plywood with the grain running across the shelf instead of the length it will sag with just a little bit of weight on it.

[edwinshap1]

If you guys are talking about the run of the grain on the above image, it's just a rendering I set so it wouldn't be a generic gray like the background.

I'll have to see which way works better. It's a 4'x8' router table so I can place the board either way. And yes it's 5 ply.

[CarVac]

I see. If it were 9-ply it would be more isotropic, but 5-ply is less so.

[edwinshap1]

Below is a picture of the CRs and fins. Cut with a Techno 4896 Wood Lathe.

I missized the CR files. The small diameter holes for the outboards are the size of the motor case, not the tube they should fit into. I'll have to recut them. I'll try to snag a picture of that, it's pretty great.

[jd2cylman]

Below is a picture of the CRs and fins. Cut with a Techno 4896 Wood Lathe.

I missized the CR files. The small diameter holes for the outboards are the size of the motor case, not the tube they should fit into. I'll have to recut them. I'll try to snag a picture of that, it's pretty great.

Man, you gotta get that pigeon out of the house before the fins take any more hits.............

Adrian

[cwbullet]

Below is a picture of the CRs and fins. Cut with a Techno 4896 Wood Lathe.

I missized the CR files. The small diameter holes for the outboards are the size of the motor case, not the tube they should fit into. I'll have to recut them. I'll try to snag a picture of that, it's pretty great.

Do you own a wood lathe?

[edwinshap1]

Do you own a wood lathe?

My Physics professor bought two CNCs. A CNC wood lathe and a CNC mill. Every part is cut to within 0.001" tolerance, which while not important for this project, is nice to have when milling the injector for my liquid engine.

[UPscaler]

Hey, a lot of people just slide the cases right in, no tubes needed


Braden

[edwinshap1]

While I could mill a nice aluminum bulkplate to fit perfectly into the tube, it would require spending a lot of time I don't have. I've already created the cut files, and resizing the outboard holes is a two minute task. Plus I've got the tubes laying around :P

[AHansom]

My Physics professor bought two CNCs. A CNC wood lathe and a CNC mill. Every part is cut to within 0.001" tolerance, which while not important for this project, is nice to have when milling the injector for my liquid engine.

Is the mill large enough to fit the body tube and do the fin slotting?