Sneak Peak: Jolly Logic's Easy Dual Deployment

[EXPjawa]

Maybe, but the testing will show the limits. I can see the possibility, though, of a beefed-up unit that uses nylon banding and is pretentioned in set up (like a ratchet strap) and the servo pulls some sort of quick release. A device like that could potentially displace the current dual-deploy systems that are typically used in HPR rockets and up. The way I see it, John's new Magic Beans Device is just a start for a new category of DD product - a prototype of what can come later with continued development.

 

[John Beans]

This is a new type of product to consider, and folks will get creative.

I think it will surprise you how big of a parachute and how much load can be creatively held by a simple lightly-loaded release like this.

For instance, you can thread loops/rings in the shock cord onto a rod that is then pressed down by the release. When the release lets go, the rod is free to flip over and let the ring(s)/loop(s) slide off it.

Stuff like that. Start dreaming them up!

 

[K'Tesh]

I certainly want to play with a couple of them...

 

[nute]

Thanks for the great report. I'll definitely be getting one come Christmas

Nate

 

[Kruegon]

The possibilities that this gadget opens up for models from about 1.6 inches in diameter on up are really intriguing. One that I’m personally excited about is fulfilling my goal to fly a mile high on a fairly small model (no level 2 cert needed). I am not too eager to get into all that one has to in order to do dual deployment (getting black powder, LEUP, etc., etc.) and I was wondering about how I was going to have a reasonable chance of getting the model back (even if I get my EggFinder built and installed). Now I have the answer. For another half-ounce I have a simple, reliable way to deploy the main at 500 feet or 300 feet. I might have to take the drag hit for a larger diameter (rather than being able to go minimum diameter on 29mm motors) but that will be a worthwhile trade I think.

The one issue I see here is the motor eject. Do you think that you can get the delay long enough to allow a flight that high without early ejection? That's my biggest concern with using the chute release for extreme altitude.

However, there's some serious potential for the right rockets. Not to mention the basic fact the chute release is a heck of a lot lighter than an a/v bay. Mine clock in right around 8oz. Less weight is better for higher altitude.

 

[rharshberger]

Optimum weight is best for altitude, too little or too much and drag will decrease the max altitude.

 

[BEC]

The one issue I see here is the motor eject. Do you think that you can get the delay long enough to allow a flight that high without early ejection? That's my biggest concern with using the chute release for extreme altitude.

That is a concern. I haven't even begun to start designing yet, and I am aware that the longest burn CTI motors that I'd be inclined to use don't have the longest delays available (which frustrates me). That's a winter project - to even start thinking about that in any sort of Open Rocket sort of way..... But whatever I come up with, the half-ounce of a JL Chute Release will be part of the package.

 

[CzTeacherMan]

That is a concern. I haven't even begun to start designing yet, and I am aware that the longest burn CTI motors that I'd be inclined to use don't have the longest delays available (which frustrates me). That's a winter project - to even start thinking about that in any sort of Open Rocket sort of way..... But whatever I come up with, the half-ounce of a JL Chute Release will be part of the package.

The Longburn motors have a shorter delay because typically, high power rockets are larger and heavier, therefore need a shorter delay. Also, the delay grain starts burning at the same time as the motor, therefore a longer burn time just means that the delay ends up being shorter.
As far as hitting a mile high, I've got a Wildman Interceptor Sport that I've launched on a 38-4 grain White Thunder (I470), intending on breaking a mile. I knew I would need some sort of dual deploy for this rather extreme rocket, so I built it using an APE nosecone sled and rigged it up for cable cutter. It all fits, barely, but I found that the cable cutter was a pain with so many extra lines to worry about... Unfortunately, on that flight, the rocket separated on the way up, my chute shredded and I lost the cable cutter. Chute Release means I can avoid the apogee charge and go with motor eject, and obviously I can ditch the cable cutter.
All that means that I can fly the Chute Release in a very high acceleration, high altitude, high speed situation. 54mm airframe, 38mm motor mount, 24" Chute, tracker taped to shock cord, 2.5lb rocket on an I470WT. If it works on that flight at MWP, it'll work on any of the applications people have discussed here.

 

[Buckeye]

That is a concern. I haven't even begun to start designing yet, and I am aware that the longest burn CTI motors that I'd be inclined to use don't have the longest delays available (which frustrates me). That's a winter project - to even start thinking about that in any sort of Open Rocket sort of way..... But whatever I come up with, the half-ounce of a JL Chute Release will be part of the package.

I think you will find a CTI motor with sufficient delay to fit the bill. I used the I216 for my mile shot - DD but motor backup also

 

[BEC]

I think you will find a CTI motor with sufficient delay to fit the bill. I used the I216 for my mile shot - DD but motor backup also

I hope so. I don't have any Aerotech hardware any more (sold my one 18mm case). So far I've only looked closely at 29mm CTI because that's what I have.

More research needed. As I say - for a little later.

/thread drift


added later: I just discovered I'd already been working on the mile high thing in OR and see that there are a couple of 6G 29s and one 5G (the Mellow) that actually look like they'd work out. I guess I need to get a 6G case and start getting serious about this

 

[ksaves2]

Since one is not deploying a full sized main chute, there is likely going to be a little more leeway in delay choice. We get fixated on simulations and drilling grains and such to avoid zippers but I foresee that with a chute release, a little late on the motor delay is probably not going to result in damage as it would
with apogee deployment of a main chute. Kurt Savegnago

The one issue I see here is the motor eject. Do you think that you can get the delay long enough to allow a flight that high without early ejection? That's my biggest concern with using the chute release for extreme altitude.

However, there's some serious potential for the right rockets. Not to mention the basic fact the chute release is a heck of a lot lighter than an a/v bay. Mine clock in right around 8oz. Less weight is better for higher altitude.

 

[ksaves2]

Yeah,

Problem with the small Aerotech hardware is stick it in a small rocket and one is more likely to lose it. That's a lot of $$$$$. Makes one use it cautiously.

Kurt

I hope so. I don't have any Aerotech hardware any more (sold my one 18mm case). So far I've only looked closely at 29mm CTI because that's what I have.

More research needed. As I say - for a little later.

/thread drift


added later: I just discovered I'd already been working on the mile high thing in OR and see that there are a couple of 6G 29s and one 5G (the Mellow) that actually look like they'd work out. I guess I need to get a 6G case and start getting serious about this

 

[noffie79]

I really could've used this product today on my L1 cert flight! Hurry up and go to market!

 

[chuck5395]

Random thought here....
Could you use this device to hold your drogue chute in a DD configuration so that your initial decent is more like drogue-less or a streamer. Then you could begin to slow the decent rate down by opening your drogue followed later by your main at yet a lower attitude? Would this then be considered "tri-deployment" (TD)?

Example:
Apogee at 14,000 feet (Deploy drogue chute that is contained by this new device)
@ 2,000 feet, release the drogue
@ 800 feet, deploy your main

I don't know, just a thought.

 

[wighty44]

Random thought here....
Could you use this device to hold your drogue chute in a DD configuration so that your initial decent is more like drogue-less or a streamer. Then you could begin to slow the decent rate down by opening your drogue followed later by your main at yet a lower attitude? Would this then be considered "tri-deployment" (TD)?

That's quite a good idea and could really help to recover within launch area boundaries...

 

[Bat-mite]

Would make for a great HPR closest-to-the-pad contest.

 

[John Beans]

Random thought here....
Could you use this device to hold your drogue chute in a DD configuration so that your initial decent is more like drogue-less or a streamer. Then you could begin to slow the decent rate down by opening your drogue followed later by your main at yet a lower attitude? Would this then be considered "tri-deployment" (TD)?

Example:
Apogee at 14,000 feet (Deploy drogue chute that is contained by this new device)
@ 2,000 feet, release the drogue
@ 800 feet, deploy your main

I don't know, just a thought.

Sure, one Chute Release per event.
Set each for whatever altitude you want (although there is no 2000 foot setting planned, the max right now is 1000.
If it's a heavy rocket and you're concerned about descent speed, I'd blow out a heavy duty, small drogue at apogee to limit that.
Then a small chute at 1000 to slow further.
Then the main at 300-400.

One thing to keep in mind is that chutes reach terminal velocity surprisingly quickly. In other words, once a chute is open, your rocket is as slow as it's going to get in a surprisingly short time (depends on chute size and how heavy the rocket is). Run a sim on your rocket and look at the altitude graph after deployment to see how long it takes for the altitude graph to reach its final slope.

I may change my tune as I test with heavier rockets, but so far the altitude I choose is based on my confidence in how long it takes the parachute as I have wrapped it to unfurl after being released. The two longest distances I've seen for one of my chutes to open and slow so far are 110 and 130 feet. Most of the time it's closer to 50 feet.

Right now Chute Release monitors descent rate and triggers right on the set altitude. I may add a certain amount of pre-release so that typical unfulrlizations (new word) typically happen a little closer to the set altitude. Something like 50-75 feet, with the risk that a "perfect" unfurl might end up a little higher than the setting. Not a huge hazard, in the scheme of things.

 

[ksaves2]

Random thought here....
Could you use this device to hold your drogue chute in a DD configuration so that your initial decent is more like drogue-less or a streamer. Then you could begin to slow the decent rate down by opening your drogue followed later by your main at yet a lower attitude? Would this then be considered "tri-deployment" (TD)?

Example:
Apogee at 14,000 feet (Deploy drogue chute that is contained by this new device)
@ 2,000 feet, release the drogue
@ 800 feet, deploy your main

I don't know, just a thought.

One comment here about this paradigm. If the descent rate is too slow, could delay the full deployment of the main chute when it's blown out by a standard charge. It would be an interesting program to run though. In that case, might be wiser to have a device where a higher altitude could be selected to unfurl the drogue. For now, I can't wait to try it on my ASP WAC's which use MAD units for apogee deployments. With one of these on the main chutes, I can make them
DD with minimal work. Kurt

 

[wcravens]

Right now Chute Release monitors descent rate and triggers right on the set altitude. I may add a certain amount of pre-release so that typical unfulrlizations (new word) typically happen a little closer to the set altitude. Something like 50-75 feet, with the risk that a "perfect" unfurl might end up a little higher than the setting. Not a huge hazard, in the scheme of things.

As a consumer this would really bother me. I would rather know that the 'latch' is released at the altitude that the device was set at. This is the expected behavior. It's not for the device to try and determine what's going to happen after the latch is released. It may not even be a chute. Much better to trigger as close to altitude as possible and leave the rest to the consumer/user. $0.02

But then again, I guess you did name it the 'Chute release'.

Wes

 

[morlock]

As a consumer this would really bother me. I would rather know that the 'latch' is released at the altitude that the device was set at. This is the expected behavior. It's not for the device to try and determine what's going to happen after the latch is released. It may not even be a chute. Much better to trigger as close to altitude as possible and leave the rest to the consumer/user.

My thoughts also.

 

[wighty44]

While I am excited about Chute Release, I began to wonder if the delayed release might result in a chute failure due to the rapid deceleration forces at the chute release point.

So I ran a RockSim simulation on the 4" Sea Wolf missile I'm presently building with a 54" Spherachute and a CTI J354 38mm motor. I set the chute to open at 1000' and ran the simulation. The launch weight of the rocket was 6.3 LBM.

The apogee was ~3,250 ft. Just after the chute deployed at 1,000 ft, the simulation data showed an initial deceleration of ~100 gees. Working that through F=MA resulted in a total force applied to the deploying chute of ~20,267 LBF divided among the chute's 8 shroud lines. That suggested that each line would experience a tensile load of ~2,533 LBF.

So the question is will that chute's shroud lines & stitching withstand that strain, or is my analysis somehow flawed?

 

[BEC]

Yes, but does the sim account for the chute and nose cone being ejected at or near apogee (and the resultant drag of that configuration as it descends) but the chute's actual opening being delayed until it's come back down to 1000 feet?

 

[wighty44]

As far as I can tell the sim does show a slight drag deceleration at apogee and then a dramatic change at 1,000 ft as the chute is opened. The graphic display also reacts as one might expect in that scenario.

 

[BEC]

Ah - OK. I've never operated in that sort of realm either on RockSim (or Open Rocket) or with real hardware. But the crux of the issue is really how fast it will fall deployed but with the chute reefed by the JL device and therefore what the deceleration is when the 'chute is allowed to open.

 

[morlock]

As far as I can tell the sim does show a slight drag deceleration at apogee and then a dramatic change at 1,000 ft as the chute is opened. The graphic display also reacts as one might expect in that scenario.

The event of a nose cone detaching and a small drogue deploying should show as more than a slight drag deceleration. Basically, you would expect the rocket to go down at about 100 feet per second (breaking my imperial units here during the fast descent portion and around 30 feet per second when the second chute deploys. Of course, these figures will vary with the choice of chute.

 

[wighty44]

The event of a nose cone detaching and a small drogue deploying should show as more than a slight drag deceleration.

I would agree, but in the scenario I first described there was no drogue - the rocket is single deploy.

 

[morlock]

Still, you need to sim for that packed chute getting out. This is pretty much like a small drogue getting out. I guess this is the easiest way to sim it.

 

[wighty44]

Ok how about this. The rocket is 4" in diameter and the packed chute can't be bigger than that. So does it seem reasonable that I add a 4" drogue at apogee? Also, I'm not sure what a good value for Cd would be for a cylindrical chute.

If that does seem appropriate, I'm open to suggestions.

 

[morlock]

I think it is a good starting point. I think both John and a beta tester have released altimeter figures showing the descent. From these, you can estimate descent rates before the chute actually opens.

You say the packed chute cannot be bigger than 4 inches. That may be true but it doesn't mean a 4 inches drogue will simulate it well. My guess is that you will have to put a fake chute a bit bigger than 4 inches to sim the first part of the descent properly. It depends if the software is taking into account the drag of the rocket itself as it tumbles down in its non rocket configuration.

 

[Flash]

This system of parachute release reminds me of how water bottle rocket fliers release their parachutes. They use a rubber band release system in several different setups.

The big difference is, this system is directly hooked to the parachute and theirs is wrapped around the airframe and trips a trap door.

Very neat system they have here. Will differently want one. It will be just the tick for local field flying to!