Au Naturale

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BABAR

Builds Rockets for NASA
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still working on an airbraker that deploys WITHOUT pull bands or springs, but uses its own momentum and airflow and mass to deploy the brakes. Stealing a bit from @Rktman ‘s early helicopters that used the ring fin for rotor stops, although here I am just using fins.


The “Au Naturale” comes from the idea that hopefully this will operate “naturally” , and gives me an excuse not to finish or paint.


The fins are two ply 1/16 balsa, as they have to handle stress in two directions, both as fins and rotor stops.

image.jpg
 
air Brakes with braces and spacers.

The thick one will be the cut where I put the hinge.

I used rubber bands and clothes pins to prevent wood glue from curling them.image.jpg
 
I have no idea what I'm even looking at, but I like it. :dontknow:

Do you have any kind of actual pen/pencil/ paper sketch... or just free lance build from your mind sketch?
 
I guesed this was a thread about how to get a good-looking metallic gold finish. Boy, was I wrong.

Either way, this looks interesting.
 
Hopefully this makes sense
My (in)famous double tape hinges, using my favorite building materials, duct tape and dental floss. Design has been far simplified from my first fancier versions over a decade ago.

Cut the wood. The extra panel provides a spacer for between the rotor (or in this case brake) and the tube, but more importantly has a cross grain direction for strength. The floss would strip through the grain otherwise.

In this case for a brake it’s a 90 degree cut. For a rotor I’d go with 85 or 80 degrees. Doesn’t take much to induce spin.

Line up the cut edges and apply and burnish the tape

Open the hinge and flip it over. Keep the cut ends pressed together

Apply and burnish the outside tape

Refold and use a needle to pre-poke the holes.

Starting from INSIDE, use a needle with floss to go through the MIDDLE section of the hinge on one side , right or left, doesn’t matter. You want to hit it where the inside and outside tapes meet. I use a spare tape piece to temporarily hold the long end of floss.

Once through, go from outside in through the pre-poked holes. Then go back through middle again and do the same thing on the other piece of balsa.

I used to do a bunch of crossings, now for low load hinges I just do one in the right and one on the left. When done I will wick the floss with thin CA (keeping the hinge moving while it dries.

I learned the double tape hinge from a Qualified Competition Rocketry (QCR) glider kit. They made some great glider and helicopter rocket kits, but unfortunately folded (bad pun) a long while back.

The “sewing” with floss was my contribution. For all practical purposes these are bullet proof, the balsa will break before the hinge. And they weight next to nothing.

Line
image.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpgimage.jpg
 
...click bait. I was expecting to see something more appropriate in the OFF THE RECORD forum per the thread title... :D

Nice pics nonetheless... good job.
 
How did you manage to violate the TEN (10) Image Limit?

Supposed to be 10 image limit; you managed to link to FOURTEEN (14) giant images....
It’s my superpower. The other is freezing computer operating systems effortlessly (and unintentionally!)
 
Moderate boo boo. I should have measured and cut the fin notches BEFORE I glued the brake hub.

Not only was it a PITB to cut them after gluing (the are two-ply, and the INNER wall is transverse to the cut), but I made at least one cut into the body tube. Not sure it’s critical (it’s 24mm and I may adapt down to 18mm, and I will add a long motor block so hopefully as long as I am not flying with the CATO-masters (aka @Ronz Rocketz and @kuririn ) I think I will be okay.

The standoffimage.jpgimage.jpg for the launch lug gives me a little more room for the nose cone shoulder (not yet built) which in this case will serve for brake retention on boost phase.

Given the expression I am not sure this has passed the Lab test yet…..
 
image.jpg

finished, closed. I got some Nerf Darts a while back used on Amazon. Package was bent out of shape and would have been useless for routine use (likely why they were sold so cheap, in small quantities these are pretty pricey to me retail, but I didn’t need hundreds). I laughed when I saw the package, didn’t matter to me, I use them for nose cone protectors or mods for models that fall nose first (typical rear eject, but some of my early helicopter rockets were designed that way). Anyhoo, at the top you see a rough model of my origami nose pyramids, you can imagine that wouldn’t be very sturdy as the initial impact point. @BEC has (IMO) correctly criticized the Estes Quark featherweight for having a pointy nose cone, thus while featherweight still might sting if it hit you, potentially severe eye injury if “heads up” called at just the wrong time.

I think my nose pyramids (aka cones) are fairly safe even in event or unintended ballistic recovery as they have no “backing”, they will just crumple if they hit anything substantial , but for both safety and durability(again this is intended to impact nose cone tip first) I cut the tip off and shoved in a cut off Nerf Dart (AND the rest of the pyramid will STILL crumple), so i think I am good on both counts.
image.jpg

image.jpg
the pyramid is EXTERNALLY shouldered, so it wraps AROUND the brakes and acts as a retention device for the boost phase. Inside is a D casing which fits INSIDE the body tube. Only NEEDS to shove out about 1/4 inch to release the brakes.image.jpg
the dowel is fixed inside the motor tube. I have multiple Kevlar attachments, (recent discussion on Kevlar thread questioned strength. I bought this a long time ago and I don’t know its strength, so I added two pieces for a total of three. One “tautens” first, if it breaks I hope the other two hold). Not a long shock cord, there is a reason. I don’t want the cord to tangle up with fins or brakes. The short cord(s) and the internal dowel should make sure the nose section STAYS forward, effectively pulling the REST of the rocket nose end DOWN. The dowel makes the nose section more of a pendulum than a free hanging weight, or at least that is the intent. It is imperative the rocket falls nose first.
image.jpg
this shows the nose section fully extended, you can see (rather, CAN’T see) the tail end of the dowel because it stays intentionally recessed in the body tube even at full extension.
image.jpg
hard to demonstrate this outside of actual flight. Theory is, at ejection, the nose is shoved mostly out, brakes are release, rocket SHOULD base on nose weight and tail drag alone orient nose down and start to fall. The brakes (the Side-Panels Of the rocket on boost) are freely hinged. They SHOULD spontaneously be force back by spontaneous air flow in the falling rocket. there are no springs or elastic pulls.

the fins are balsa 2 ply in orthogonal layers, one direction for strength of the fins on boost, the other so the leading edges of the fins act as the brake stops. The extra “backing” on the brake blades is to bolster them so impact with the fins doesn’t “break the brake blades” (try saying THAT three times fast!)
image.jpg

Another shot to show the internal nose cone motor casing. I guess you could say the nose has BOTH an INTERNAL SHOULDER and EXTERNAL shoulder.image.jpg
 
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The taped motors are just in the pic for scale/perspective. I didn’t have a single D casing handy.
 
79 grams without motor.

hmmm, motor choices. Has a 24mm mount (built on. BT-50.) I am thinking of adapting down to 18 mm. This puppy has plenty of fin area, given it's shape doesn't lend itself well to simulator programs (plus I am lazy at that, without excuse as the makers of the programs apparently make them relatively easy for cylindrical standard rockets.) Anyway, unconventional shape, but I think the fins if anything are oversize, so I would lean toward it being overstable.

Mass is a bit much for an A (unlike Estes, I actually try to FOLLOW the recommendation not to design rockets to use motors for which the maximum liftoff weight is LESS than the designed rocket ready-to-fly..... but I digress.)

As an unproven design, I want to keep first flight on the lowest motor so if fecal-turbine action occurs, it is at a lower altitude with less energy (either unburned powder or kinetic) when things go skiwampus. So that puts me at a B. Then the question is power and delay. I am thinking of B6-4. Maxi liftoff is 113 grams, so with adapter and motor still over 10 grams under max. The delay is a bit long, BUT I am thinking I would prefer delay to be a bit late rather than early. Rationale: Late ejection places this in a nose down attitude, which is EXACTLY what I would prefer. So if nose down at ejection, the ejection charge will shove the nose off with the rocket already heading nose down. The air flow SHOULD catch the blades and throw them outward. The B6 should get it off the pad with a bit more authority than the B4, so that is always good and should reduce weathercocking a bit.


I am debating putting a bevel on the forward tips of the blades that airflow would push the blades outward (and maybe a reverse bevel on the wooden square around the forward end of the tube, the purpose of that square is mainly to assure alignment of the blades on boost.)

Only problem is that bevel will weaken the tips of the blades a touch (maybe I can put Mylar tape over it?), and this thing will topple over.

So what do you guys think? Bevel? Motor?
 
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Motor: your logic sounds sound to me. For the same reasons, if you want to go higher on the second flight, C5 rather than C6.

Bevel: if I understand the whole thing (without going back and rereading the whole thread) my gut feel is that if it's needed then it won't be enough. I like that there are no springs or rubber bands or stuff like that, but... If you're concerned about the brakes opening out then maybe some little rubber pads somewhere could be added. They'd be just slightly compressed for launch, and give just a little push to ensure the brakes catch air.

On the subject of Nerf darts, the hole in the back is just the right size for a MicroMaxx engine. I'm sure no one needs to ask me how I know.
 
On the subject of Nerf darts, the hole in the back is just the right size for a MicroMaxx engine. I'm sure no one needs to ask me how I know.
not so much interested in how you know as in how it turned out? And how you put the fins on? You DID put fins on, didn’t you:rolleyes:?
 
No fins. "They go pretty straight out of a Nerf gun, so WTH, why not give it a try," says I to myself. "It's only a MicroMaxx, the yard is big; how bad can it possibly go?" "OK," myself answers, "let's go."

It went fine.
 
still working on an airbraker that deploys WITHOUT pull bands or springs, but uses its own momentum and airflow and mass to deploy the brakes. Stealing a bit from @Rktman ‘s early helicopters that used the ring fin for rotor stops, although here I am just using fins.


The “Au Naturale” comes from the idea that hopefully this will operate “naturally” , and gives me an excuse not to finish or paint.


The fins are two ply 1/16 balsa, as they have to handle stress in two directions, both as fins and rotor stops.

View attachment 564411

Thank god! I would hate to see pictures of any rocketeer making rockets in the buff.
 
79 grams without motor.

hmmm, motor choices. Has a 24mm mount (built on. BT-50.) I am thinking of adapting down to 18 mm. This puppy has plenty of fin area, given it's shape doesn't lend itself well to simulator programs (plus I am lazy at that, without excuse as the makers of the programs apparently make them relatively easy for cylindrical standard rockets.) Anyway, unconventional shape, but I think the fins if anything are oversize, so I would lean toward it being overstable.

Mass is a bit much for an A (unlike Estes, I actually try to FOLLOW the recommendation not to design rockets to use motors for which the maximum liftoff weight is LESS than the designed rocket ready-to-fly..... but I digress.)

As an unproven design, I want to keep first flight on the lowest motor so if fecal-turbine action occurs, it is at a lower altitude with less energy (either unburned powder or kinetic) when things go skiwampus. So that puts me at a B. Then the question is power and delay. I am thinking of B6-4. Maxi liftoff is 113 grams, so with adapter and motor still over 10 grams under max. The delay is a bit long, BUT I am thinking I would prefer delay to be a bit late rather than early. Rationale: Late ejection places this in a nose down attitude, which is EXACTLY what I would prefer. So if nose down at ejection, the ejection charge will shove the nose off with the rocket already heading nose down. The air flow SHOULD catch the blades and throw them outward. The B6 should get it off the pad with a bit more authority than the B4, so that is always good and should reduce weathercocking a bit.


I am debating putting a bevel on the forward tips of the blades that airflow would push the blades outward (and maybe a reverse bevel on the wooden square around the forward end of the tube, the purpose of that square is mainly to assure alignment of the blades on boost.)

Only problem is that bevel will weaken the tips of the blades a touch (maybe I can put Mylar tape over it?), and this thing will topple over.

So what do you guys think? Bevel? Motor?
I'd opt for the B4-4. It's got a little bit more max thrust and duration. Thrust also kicks in sooner.
 
Hold off the KUDOS until I get it flight tested (but thanks!)
Far less to go wrong with simple solutions vs complex ones. Ingenuity + simple is even better.
My failure rate increases with the level of complexity of anything I build (kinda the Murphy's Law of design I'd say). :facepalm:
 
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