Beyond D Tube Horizon— Horizontal Spin Recovery

[BABAR]

Figured I’d stop trolling or derailing @Dotini and start a new thread

Hoping imitation does come across as flattery. Using his plastic tubes and my old tube fin idea. Using Body Tubes worked but still not as durable.

One BT-5 two inches weighs about 0.7 grams

Same size plastic about 2.5 grams.

So about 3.2 to one.

 

[Dotini]

Figured I’d stop trolling or derailing @Dotini and start a new thread

Hoping imitation does come across as flattery. Using his plastic tubes and my old tube fin idea. Using Body Tubes worked but still not as durable.

One BT-5 two inches weighs about 0.7 grams

Same size plastic about 2.5 grams.

So about 3.2 to one.View attachment 529184

The plastic tubes I am using have a wall thickness of 0.020" to 0.025".

 

[BABAR]

Tubes I got we’re listed as 12 mm diameter, so I figured I’d get 6 around a BT-5 with a bit of room to spare.

Unfortunately they are 12 mm INSIDE diameter. Outside is about 14. I am going to epoxy 2 pairs, dry fit them, and see if I can fill remaining gap with one tube or more likely shim the BT-5 up a bit to fit three pair.

For those wondering, AFTER I glue the tube fins onto the tube, I will cut out the segment of each tube that will allow it to spin.

Tube fins are nice for alignment when you glue them in pairs.

I am using Loctite 5 min epoxy

 

[BABAR]

The plastic tubes I am using have a wall thickness of 0.020" to 0.025".

So about 0.0635 mm upper.

I think mine are thicker.

 

[BABAR]

https://smile.amazon.com/gp/aw/d/B0874TKDNZ?psc=1&ref=ppx_pop_mob_b_asin_title
Says 12 mm outside diameter, but clearly wrong. 1 mm thick per listing.

 

[lakeroadster]

 

[BABAR]

I saw a Blue Plymouth Horizon in San Francisco while I was at UCSF, license plate “BYOND D”

 

[BABAR]

@Dotini , I am stealing your modular fin can idea too. It will be easier to handle a smaller section when I cut the sections out, and I can play with different rocket lengths by adding sections with couplers.

 

[Dotini]

@Dotini , I am stealing your modular fin can idea too. It will be easier to handle a smaller section when I cut the sections out, and I can play with different rocket lengths by adding sections with couplers.

To be fair, the modular fin can idea was from my esteemed associate, Blair, a rather brilliant retired Boeing engineer. I got him involved in kart racing 20 years ago, and now I've got him involved in rocket science!

The advantages of modular fin cans and sections is considerable. It's a solid basis for objective testing and experimentation.

 

[BABAR]

I always like dual purpose components for rockets.

In this case, I believe the length of an Estes mini engine is 1 inch and 3/4.

So my phone can I will make 2 1/4 inches long.

The motor will stick into this one and a half inches, with 1/4 inch sticking out which will give me enough room for a tape wrap. (I don’t have my engine hooks with me at the moment.)

I will then put in a homemade coupler which will be 1.5 inches long, 3/4 of an inch will stick into the fin can body tube to serve as both the coupler and the engine block for the motor, the other three-quarter inch will stick out forward as a coupler for the parts that I will add on later.

The tape roll has cuts in it to make strips I will use to shim the body tube as the PETG. Tubes are just a bit larger.

 

[BABAR]

Cuts and dry fit

 

[BABAR]

not pretty but workable

 

[jmasterj]

Looks good! How do you plan to cut the plastic tubes?

 

[BABAR]

19.2 grams, and I still need to add six epoxy fillets. Heavy!

Of course, I will be cutting out about 1/5 of each tube, so probably will be a wash.

@Dotini , what’s the weight of your fins?

 

[BABAR]

Looks good! How do you plan to cut the plastic tubes?

Good question. I tried the transverse cuts with a blade and after 45 minutes got nowhere, but DreMel does it pretty quick (although you loose about 1mm, as it kind of melts it while it cuts it.)

there will be two lengthwise cuts in each tube.

the easy one is at the apex of each tube (point farthest from body tube.)

the second is going clockwise, as close as I can to the next tube.

see post 8 here

https://www.rocketryforum.com/threa...-previously-squirt-no-recovery-system.165609/
in fact, other than length not yet determined, this will basically be the same rocket except stealing @Dotini ‘s plastic fins.

the edges near the next tube will be rough, but I think I can get some sort of Dremel attachment that should even it out a bit.

 

[lakeroadster]

Do you work from sketches or plans of any sort or are you winging it... or should I say tubing it?

 

[neil_w]

BT5 is extremely flimsy, but what about couplers? I would guess they're about midway in strength between the BT5 and that plastic. But they would be much easier to cut and glue.

Just pondering.

 

[BABAR]

Do you work from sketches or plans of any sort or are you winging it... or should I say tubing it?

Unfortunately except for my Helis and AirBrakers, where I have to run some numbers to get the parts to fit, I usually just start building, I messed up here because on the fin can module, where I DID remember to leave 1/4” behind the fins for an external tape wrap motor retention, I FORGOT to leave the same on the front, for a tape wrap for next module.

Fortunately I made the coupler extra long, so I should still be able to tape the sections together. I am going to start with two 18” tubes, so a length to diameter will be about 70-80. The Squirt worked with a ratio of about 24.

 

[BABAR]

BT5 is extremely flimsy, but what about couplers? I would guess they're about midway in strength between the BT5 and that plastic. But they would be much easier to cut and glue.

Just pondering.

Would work, and a Great compromise. I think i’d Still likely cut couplers with a Dremel, and cutting the plastic with the Dremel isn’t that hard. I don’t think my tubes are the same as @Dotini ‘s tubes, I think his flex a bit. I theeeenk his are just stiff enough to avoid fin flutter but give a nice bounce when they hit asphalt. Maybe he will chime in here. Mine are really stiff, they may shatter or chip (although I doubt it), but they also have no flex at all.

Couplers won’t EXACTLY fit the 6 to 1 ratio which is so inherently nice on many tube finned rockets. But wouldn’t take much shimming to get a good fit, they come cut to length already. Might require more finish work, the ones I have see are tougher than body tubes and sometimes have deep spirals (usually not a problem because they are of course normally internal and unfinished.)

I still think @Dotini ‘s plastic is going to be one of the best if not THE. Eat solution.

 

[neil_w]

Couplers won’t EXACTLY fit the 6 to 1 ratio which is so inherently nice on many tube finned rockets. But wouldn’t take much shimming to get a good fit, they come cut to length already. Might require more finish work, the ones I have see are tougher than body tubes and sometimes have deep spirals (usually not a problem because they are of course normally internal and unfinished.)

Ok, here's one more variation: glue a coupler into a piece of BT5, and then use that. You'll get the strength of the coupler (and then some), the smooth finish of the BT5, and the perfect 6-to-1 fit.

 

[BABAR]

Ok, here's one more variation: glue a coupler into a piece of BT5, and then use that. You'll get the strength of the coupler (and then some), the smooth finish of the BT5, and the perfect 6-to-1 fit.

ALMOST perfect. Certainly good enough for me, but my bar is extremely low. However, because of the cut (see the Squirt thread) you will still see (and being the kind of craftsman that even fits his vent holes into the rocket finish design will feel the neeed to finish) the internal side of the coupler.

And finishing the INSIDE of a BT-5 coupler ain't gonna be a walk in the park.

 

[neil_w]

Just paper the interior. After it's cut open it doesn't seem like it would be that difficult.

Yes, I am determined to prove the viability of this idea.

 

[BABAR]

Just paper the interior. After it's cut open it doesn't seem like it would be that difficult.

Yes, I am determined to prove the viability of this idea.

Cool! I think these are going to make very nice small field rockets. They will come down a bit fast (so they won't drift) but they should be fairly robust for recovery even on hard surfaces.

 

[BABAR]

Rough cut out segments with Dremel. Took about 10 minutes to make 12 cuts. The segment removed is pretty small. Will use another dremel tool to smooth things up. So far fin can 15.1 grams (added epoxy fillets.)

The small piece is the excised segment.