Chute Delay for Second Stage

[Bruiser]

Let's say you were looking at a two stage design similar to this design.



Basic parameters are:
1.64 diameter
Around 30 inches long
Estes 24mm "D" engines
Direct staging
Sims out to about 1,400 feet

The question concerns recovery. I am a bit concerned about it drifting for a looong distance if there is a breeze. It seems there are two ways to have the chute release/open at a lower altitude, those being either a chute release or a delayed deployment using an altimeter and some sort of charge.

The chute release I can wrap my head around. Seems pretty simple but I don't think it'll work in the 1.64 diameter tube.

The altimeter/charge I just can't grasp. Is this rocket to small for that also. Could someone explain to me a very basic system that could be used on this rocket if one does exist?

Thanks,
-Bob

 

[heada]

For the booster stage, you can use "tumble recovery" where it doesn't have a parachute and just tumbles down from where it staged. You could also have an inter-stage coupler that uses electronics to ignite the upper stage and use the booster motor to eject a parachute. For the sustainer stage, you can use the normal motor ejection for the parachute or add a coupler and bulkheads and create a dual-deploy system that uses electronics to deploy a drogue parachute at apogee and another main parachute at a pre-programmed altitude. Electronics, including a battery, can fit in a 1.64" tube without issue. Some of the smaller set ups will fit in 29mm and 24mm tubes but I find that is too difficult to work with.

 

[mbeels]

An altimeter/charge would work, the smallest ones that I'm aware of will fit into 24mm (1") BT-50 tube. The simplest approach would be a drogueless dual deploy, use motor eject to separate the rocket at apogee, and then the altimeter to deploy the main parachute at a predetermined altitude. You could build your own avionics bay, or purchase a kit such as this one: https://www.apogeerockets.com/Electronics_Payloads/Electronic_Bays/BT-60_Ebay_Kit?cPath=42_194&

 

[mbeels]

The Eggtimer Quark would fit in there pretty comfortably. The principles are the same as dual deploy in a larger rocket, everything is just smaller. I have a BT-55 (33mm) dual deploy rocket, it is tight, but it is a lot of fun to fly.

 

[boatgeek]

The Chute Release will fit into a 38mm tube, which is a hair smaller than the 1.64" tube you're working with. You have to be cautious with how the chute is packed and folded. See here for how I do it: https://www.rocketryforum.com/threads/jlcr-in-38mm-rockets.149016/#post-1829262 I'm sure there's other ways to do it; this is just what worked for me.

 

[Nytrunner]

Agreed with Boat.

Chute release fits fine in a BT-60 with plastic chutes (mind the couplers). Nylon chutes are probably fine too.

 

[Kartman]

I have used the Jolly Logic Chute Release with BT 60 diameter rockets for years. Works great.

Tom

 

[Bruiser]

So jolly logic sounds pretty simple. If I understand this correctly the sustained motor deploys the chute like normal around the apogee and then the rocket falls to whatever altitude the ol is set at, then the chute opens and it floats safely the the launch area. Is it possible that the ricket could fall so fast that the chute drips clear of the rocket upon deployment ot will the drag of the rocket being separated keep it at a safe speed for chute opening.

Regarding the other option I dont know about dual deploy. So what would be considered a basic system? Does the sustained need a plugged motor so the ejection charge does separate the nose cone and deploy the chute? So how much extra weight is involved?

-Bob

 

[dr wogz]

So jolly logic sounds pretty simple. If I understand this correctly the sustained motor deploys the chute like normal around the apogee and then the rocket falls to whatever altitude the ol is set at, then the chute opens and it floats safely the the launch area. Is it possible that the ricket could fall so fast that the chute drips clear of the rocket upon deployment ot will the drag of the rocket being separated keep it at a safe speed for chute opening.

Regarding the other option I dont know about dual deploy. So what would be considered a basic system? Does the sustained need a plugged motor so the ejection charge does separate the nose cone and deploy the chute? So how much extra weight is involved?

-Bob

Bob, concerning the JLCR, yes, that's I basically it. Will it come is soo fast that you need worry about zippers or the chute being ripped off? Not really, not for this size of rocket. I would suggest a small 2" x 18" streamer to give yourself a little added confidence, and something 'shiny' to look for on decent.

yes the basic "Dual Deploy" system is a plugged motor (or one with a delayed charge) and an altimeter capable of firing a charge (or two) at apogee (or at apogee and at a set altitude - as most do)

typical dual deply flight:

• 3.. 2.. 1.. blast off
• rocket goes up under power.
• rocket coasts to apogee
• altimeter fires at, or slightly after apogee. At this point, usually the drogue chute is ejected, and the rocket is falling in 2 pieces, under a small drogue chute or a streamer. Some leave off the chute, and the split rocket is enough to slow its decent and keep it at a reasonable rate. Some will eject their main, but it's bundled in a JLCR, therefore not needing the 2nd deployment charge.. Some use the built-in motor deployment as a 2nd (or 3rd) redundancy charge. (If the sim says to use a J350-7, 7 being the suggested delay, some might drill the delay to 8 or 10 to ensure a charge does go off! but will after the main expected event.)
• the altimeter will then fire the 2nd charge at the prescribed altitude, deploying the main recovery chute. (this is usually from the upper tube, the AV bay, and the NC pops off) That is, if the system is set up for a drogue & main recovery system..

In your case, a 2-stage D to D motors in a small-ish tube, the JLCR is probably your best bet.

 

[Bruiser]

I did find a you tube video that confirmed the chute release will work in a bt60 tube. Another member sent me a link to a video by apogee that showed how to build thier electronics bay for dual deployment. I still havent found anything about using the Estes black power ejection charge for the first deployment of a streamer or small chute followed by the delayed deployment of the larger chute by the electronics. Seems like you'd just use a single charge...

I've worked on different size body tubes and engine sizes and I have found with a bt 60 tube and a 24 mm in the booster and a 18mm in the sustaine I can run the gamit from 900 feet to 1600. I could get the altitude with 18mm in both but not enough speed off the rail.

 

[BABAR]

Keep it simple

Unless you are already familiar with electronics and dual deployment, probably best NOT to start learning on a 2 stage rocket.

Stay with black powder, since that is what you know.

Go with D12-0 on booster.

Something to CONSIDER is adapting down from 24 mm D12-7 on sustainer to an 18 mm A8-5. I say CONSIDER because I am not sure the 18mm ejection charge will deploy your chute given your body tube size /volume. From an upward flight standpoint it will only moderately reduce the sustainer ascent duration (around 9 seconds for D12-7 and 6 for A8-5) but I expect substantially reduce your altitude. Depending on field size and win conditions, you may not NEED dual deploy.

If either you don’t think an 18 mm ejection charge will be enough, or you decide for other reasons to stick with a D in sustainer, and you aren’t experienced in electronics, for your first two stage likely JLCR s best bet.

Wishing you two straight trails!