Chute Release

[Tobor]

...I've thought that something like this would be an interesting option where instead of bundling the chute with the elastic, make a cylinder to contain the chute. The cylinder would be split lengthwise and spring loaded - think fly-away rail guide kind of thing. The elastic would hold the cylinder shut and once the elastic is cut the cylinder springs open and releases the chute. I think this cylinder idea would significantly reduce the chance of tangles and would make it possible to use this elastic idea on larger chutes.

I've had nearly the exact same idea bouncing around in my head since I saw one of Joe Barnard's BPS videos last year. Now that I am building rockets big enough, I might just give it a go.

 

[Greg Furtman]

Video "should" work now..

Wallace, it works now. Thanks for the effort!

 

[Wallace]

Cool, hope it gives inspiration. In my mind at least, having "stored energy" in the chute bundle by wrapping it tightly should give better results in actual opening (vs simply releasing) of said bundle upon release. The example in the video was not wrapped very tightly since it was basically proof of concept for the elastic burn string.

 

[Greg Furtman]

Cool, hope it gives inspiration. In my mind at least, having "stored energy" in the chute bundle by wrapping it tightly should give better results in actual opening (vs simply releasing) of said bundle upon release. The example in the video was not wrapped very tightly since it was basically proof of concept for the elastic burn string.

So what software were you using on your smartphone? And were you communicating to the Quark?

 

[Wallace]

Not a Quark, was a Quantum. No software necessary, simply connect to it through WiFi on any device that has a browser. Very cool design that also eliminates need for switches and makes programming/setup and downloading flights super simple. All that for 40 bucks is a steal, just need to assemble it yourself. Personally I enjoy building Eggtimer stuff but if for some reason you absolutely can't do it yourself there are others that will do it for a marginal fee.

 

[Greg Furtman]

Not a Quark, was a Quantum. No software necessary, simply connect to it through WiFi on any device that has a browser. Very cool design that also eliminates need for switches and makes programming/setup and downloading flights super simple. All that for 40 bucks is a steal, just need to assemble it yourself. Personally I enjoy building Eggtimer stuff but if for some reason you absolutely can't do it yourself there are others that will do it for a marginal fee.

Wallace, I just checked out the Quantum. Pretty nice for $40 and I like that it has a web interface that I could use with my Galaxy S7 or 8" ASUS Android tablet.

 

[Sabrina]

Just in case you "older" dudes forgot about us younger dudes...

The JLCR is revolutionary because its so simple, and self-contained, but the really big deal for me - NO PYRO!
That means (at 16 yrs old) I can use it by myself without an adult mentor as long as the rocket flys on single-use F motor or below.

.... Now if they were just a bit smaller and fit into smaller airframes...

 

[mpitfield]

Sabrina, it's revolutionary for us old dudes as well. Besides once you are old enough to use BP, the novelty will wear off the first time you clean your recovery gear, or inspect the holes in your nice new chute.

Just in case you "older" dudes forgot about us younger dudes...

The JLCR is revolutionary because its so simple, and self-contained, but the really big deal for me - NO PYRO!
That means (at 16 yrs old) I can use it by myself without an adult mentor as long as the rocket flys on single-use F motor or below.

.... Now if they were just a bit smaller and fit into smaller airframes...

 

[Greg Furtman]

Just in case you "older" dudes forgot about us younger dudes...

The JLCR is revolutionary because its so simple, and self-contained, but the really big deal for me - NO PYRO!
That means (at 16 yrs old) I can use it by myself without an adult mentor as long as the rocket flys on single-use F motor or below.

.... Now if they were just a bit smaller and fit into smaller airframes...

Sabrina, keep your eyes on this thread. For the price of an Eggtimer Quantum and maybe another $10 you can build something for less that half the price of a JLCR. Wallace is on the right track. I'm pumped.

 

[Wallace]

Sabrina, keep your eyes on this thread. For the price of an Eggtimer Quantum and maybe another $10 you can build something for less that half the price of a JLCR. Wallace is on the right track. I'm pumped.

And don't forget, also non-pyro so you'd be "allowed" to use it. You also get the satisfaction of designing and building it yourself.

 

[Greg Furtman]

And don't forget, also non-pyro so you'd be "allowed" to use it. You also get the satisfaction of designing and building it yourself.

Yes, there is much satisfaction in making something yourself.

Wallace, is this the kind of wire you use?

https://www.amazon.com/Nichrome-80-...506&s=gateway&sprefix=nichrome,aps,220&sr=8-6

 

[Wallace]

I suspect that'd be fine but I used 36 gauge. You need to measure the resistance and make sure whatever electronics you use can handle the load. Resistance varies with Nichrome wire length,that's why I decided to use the zip tie holders, for an easy way to get consistent distance between contact points. Use your imagination when coming up with a design, I'm sure there are countless ways to achieve the same effect. Don't see why you couldn't put the whole mess in a short piece of tube and anchor it to your shock cord @ the chute mounting point, would make for shorter wire runs. I've not had any tangles (yet) using it in a noscone av bay and bundling the chute tight to the base. I'm actually partial towards the Ematch/nylon bushing design since it's so easy/less fiddly to set up. Downside is it requires an Ematch..

 

[ebruce1361]

Sabrina, keep your eyes on this thread. For the price of an Eggtimer Quantum and maybe another $10 you can build something for less that half the price of a JLCR. Wallace is on the right track. I'm pumped.

Yes, there is much satisfaction in making something yourself.

I love Jolly Logic Altimeters, but the cost and size of the Chute Release are the only things that I have against it. Wallace's rig is fantastic for simplicity and being incredibly small. The rig I'm building will be more self-contained, but slightly bulkier. Either way, there absolutely is a satisfaction in building your own hardware.

@Sabrina, do some reading on electronics or watch videos on youtube from "Element 14 Presents". The kinds of electronic gizmos one can build with just a little bit of money are endless. Just look at the Arduino or Raspberry Pi. Full-blown computers for $30 that can do whatever you design them to do. It is absolutely possible to make your own chute release or other equipment for a fraction of the cost of a commercially available version. Plus, it's YOUR design. One-of-a-kind. It's a feeling just as good if not better than having a scratch-built rocket that literally nobody else has.

 

[billdz]

Resistance varies with Nichrome wire length,that's why I decided to use the zip tie holders, for an easy way to get consistent distance between contact points. Use your imagination when coming up with a design, I'm sure there are countless ways to achieve the same effect.

Wallace, no need to use much imagination, your design looks great and is groundbreaking. I just ordered some nichrome wire and 2mm elastic cord, I've got to try this. How much resistance do you see across the contact points? In your earlier post, you mentioned rubber bands but said they sometimes caught on fire. Is the elastic bead cord less flammable? And do you have a photo of the unit and chute as connected to the nose cone? Seems that may be an issue, keeping the chute close enough to the nose cone so that the wires to the Quantum do not break off.
Many thanks,
Bill

 

[Charles_McG]

I did something a bit like Wallace’s about 4 years ago - when the Quark first came out.

Eggtimer Quark based chute tender
https://www.rocketryforum.com/index.php?threads/Eggtimer-Quark-based-chute-tender.129976/

I’ve gotten a lot of use out it it - including L1 and L2 flights.

 

[billdz]

I did something a bit like Wallace’s about 4 years ago - when the Quark first came out.
I’ve gotten a lot of use out it it - including L1 and L2 flights.

Thanks, Charles, looks very nice. What did you end up doing to get a good electrical connection to the nichrome?

 

[Charles_McG]

Thanks, Charles, looks very nice. What did you end up doing to get a good electrical connection to the nichrome?

I'm still using the power supply wire terminals. I tug on the nichrome after I tighten the screws to make sure I can't pull it out. It seems to be fine if I've got a good mechanical connection.

 

[billdz]

Congrats on this, you and Wallace deserve a lot of credit, I'm surprised the invention is not being more widely used (at least not yet).

This is the line in your other post to which I was referring: "what I've learned from my little tender is that it's really hard to get a good electrical connection to nichrome. That part is still a work in progress." So it's just a matter of getting the screws nice and tight?

 

[Charles_McG]

Congrats on this, you and Wallace deserve a lot of credit, I'm surprised the invention is not being more widely used (at least not yet).

This is the line in your other post to which I was referring: "what I've learned from my little tender is that it's really hard to get a good electrical connection to nichrome. That part is still a work in progress." So it's just a matter of getting the screws nice and tight?

Getting a tight connection on the wire terminals is key - but not always easy. So I've learned to tug-check both sides -every- time. The screws can be tight, and the nichrome slides right out. It's slick. Wallace's screwdowns look sturdier.

My version, where I'm using monofilament as the fusible link, is a bit of a pain to prep. I use fishing tackle to make connections, and provide spots for lanyard attachments so I'm not loosing pieces every flight - but it's still sitting down and tying little knots. I prep 5-6 in a session and keep them in a ziplock. The rubber bands decay faster than I would have guessed, too.

It adds up to a fair amount of fiddly-ness. It's not an elegant, finished product like the JLCR.

But it's -cheap-.

 

[Wallace]

Wallace, no need to use much imagination, your design looks great and is groundbreaking. I just ordered some nichrome wire and 2mm elastic cord, I've got to try this. How much resistance do you see across the contact points? In your earlier post, you mentioned rubber bands but said they sometimes caught on fire. Is the elastic bead cord less flammable? And do you have a photo of the unit and chute as connected to the nose cone? Seems that may be an issue, keeping the chute close enough to the nose cone so that the wires to the Quantum do not break off.
Many thanks,
Bill

Although I know I do have pictures "somewhere" I cannot currently find 'em. Setup with a nosecone av bay is as simple as looping the elastic string through your eyebolt or whatever you're using for recovery retention and around your chute bundle/cord at the same time. Holds everything tight to the nosecone so no loose or dangling wires until it releases. Make sense? And, no, never had a problem with the elastic beading cord actually burning...

 

[Buckeye]

It adds up to a fair amount of fiddly-ness. It's not an elegant, finished product like the JLCR.

But it's -cheap-.

Exactly. These are not new concepts. 10 years ago, I also messed around with various homemade burrito cutters, cable cutters, hot wire cutters, fishing line, rubber bands, ematches, BP vials, tethers, etc. They seemed to work OK on the bench, but they were far less reliable in the air. I gave up on it and went back to classic two-tube DD, since I was already using a full-featured altimeter to control the events. And yes, fiddly as hell.

The JLCR is elegant and proven. My time is worth more than the $150 price tag. I do enough DIY in this hobby. I don't have to make everything from scratch to be happy.

 

[Wallace]

Obviously not everyone's cup of tea...

 

[prfesser]

One of the early chute release devices was the Tether. An ematch and a tiny amount of BP, maybe 0.1 gram, went into a cup in the green anodized halves. Two stainless-steel tabs were on either end of a cord, which held the chute burrito closed. When the match popped, the two halves of the device separated, the tabs were released, and the cord no longer held the burrito closed. Sounds a bit complicated but it was actually pretty simple to prep, and it worked perfectly each time I used it. (The one in the image is unused, bought just before the company went out of business.) The most difficult part of assembly was getting the match head, BP, and a piece of masking tape (wrapped around the match head and holding the BP) crammed into the cup of the device.

 

[billdz]

Setup with a nosecone av bay is as simple as looping the elastic string through your eyebolt or whatever you're using for recovery retention and around your chute bundle/cord at the same time. Holds everything tight to the nosecone so no loose or dangling wires until it releases. Make sense?

Makes sense, thanks much. The elastic string is strong enough to withstand the shock of ejection and hold the chute and shock cord securely to the nose cone until the nichrome fires? Do you attach the chute to the eyebolt or further down the shock cord?

 

[billdz]

The JLCR is elegant and proven.

Agreed, I have 2. And John Beans provides great support.

 

[Wallace]

Makes sense, thanks much. The elastic string is strong enough to withstand the shock of ejection and hold the chute and shock cord securely to the nose cone until the nichrome fires? Do you attach the chute to the eyebolt or further down the shock cord?

About 1/3rd of the way down. Just bundle the "shorter" length of cord in with everything else and it stays put until it releases..

 

[billdz]

About 1/3rd of the way down. Just bundle the "shorter" length of cord in with everything else and it stays put until it releases..

OK got it, thanks again, I would guess this to be a critical part of the operation, as the shock cord must be bundled tight enough so it does not come out with the force of ejection and any recoil. And probably important to use a nice long shock cord, to minimize recoil.

I've already started putting something together, it looks like the design of the zip tie mounting base from Lowes has changed since you bought yours. Now it is necessary to put the screws on the sides rather than the corners, which shortens the length of the nichrome wire and slightly lowers the resistance. The ohm meter on your other thread shows 3.3 ohms, is that about what we want?

 

[Wallace]

As long as your electronics can handle the load (they're not all created the same) I don't think it's absolutely critical. 3.3 Ohms isn't too terribly taxing. It's been a while, but I seem to remember checking as far as the Quantum being able to handle it. Looks like your setup will probably work just fine as shown, but you can vary the final resistance with different gauge wire if it becomes necessary. Consistency is always a good thing though.

 

[Wallace]

As far as wrapping the bundle goes, experimentation is the key to getting what you feel comfortable with. You can pull that elastic string pretty tight and it's really "grabby". I've never had one come lose prematurely.

 

[billdz]

So my parts arrived today, I put it all together, and ran a bench test. The test was successful but the nichrome wire burned through. Wallace, is there some trick to adjusting it so the nichrome is reusable?

I thought I had the bundle nice and tight, but apparently it would help to make it even tighter, in Wallace's video the elastic band came off with a bigger "pop" than mine did. Also, note that the burn through occurs about one second after the timer hits zero.

I used the same parts as Wallace: 36 gauge nichrome wire (it is very thin), 2mm elastic bracelet bead cord (1mm might work better), zip tie mounting base and brass hardware from Lowes, Eggtimer Quantum, and 7.4v 2S LiPo battery. Instead of attaching the device via wire to the nose cone, however, I mounted the Quantum inside a piece of BT-60 tube and attached the zip tie base to the outside of the tube. The upside of this setup is that the device can more easily be moved from rocket to rocket. The downside is that the tube will not fit into smaller rockets.

Any thoughts?