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Low power dual deploy

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RalPh8

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I know it's been done before. I also know it's not ideal due to lack of body tube thickness. That said, is there a descent kit or at least one that is more recommendable than the others for low power dual deploy? Looking to use C or D. Not using JLCR. I only wanna use black powder. I already got an EasyMini.
 

afadeev

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I know it's been done before. I also know it's not ideal due to lack of body tube thickness. That said, is there a descent kit or at least one that is more recommendable than the others for low power dual deploy? Looking to use C or D. Not using JLCR. I only wanna use black powder. I already got an EasyMini.
Likely not low, but more of mid-power sized projects.
You really need minimal airframe space and radius to have room for the electronics and the battery.
And if you go high enough, you also need a GPS tracker, that takes yet more space and adds weight. Without a GPS tracker, I would mentally prepare to never see the rocket again after the inaugural launch. Next thing you know, C&D motors our inadequate.

Consider something along the lines of Aspire with an optimal DD avionics bay:

a
 

gtg738w

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You can absolutely fly dual deploy on those motors. Pretty much any kit with a coupler can be converted without much trouble. Even without one, you can always split the tube if the kit is long enough or just add on a converted payload bay.
 

Scott_650

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I know it's been done before. I also know it's not ideal due to lack of body tube thickness. That said, is there a descent kit or at least one that is more recommendable than the others for low power dual deploy? Looking to use C or D. Not using JLCR. I only wanna use black powder. I already got an EasyMini.
If you don’t want roll your own there are several vendors who have smaller add-on avionics bay kits - either separate payload sections or nose cone style. Unfortunately I can’t bring the nose cone bay vendor’s name to mind. Eggtimer has a nose cone mount for their new Apogee deployment altimeter. When Mach1 is back up and running after the move west they have multiple BT55 and BT60 kits that can be upgraded with an avionics bay. One of the members of my club (Gheem of The Rocketry Show podcast) does DD with BT60 based rockets pretty regularly - give him a shout on the TRS FB page, I’m sure he has some insight he’d share.
 

cerving

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I've done plenty of them. The trick is sizing the charge so it doesn't blow out the cardboard body tube, most LPR tubes are pretty thin. MPR tubes like LOC or Madcow are heavier, you can still blow them out but there's a lot more margin for error. If you use the same amount of BP that your motor came with (or just use the BP from the motor well if it's separate and/or removable) then that's not an issue. You'll probably have to get some coupler stock and plywood and build the AV bay yourself... there aren't any pre-fab AV bays for LPR rockets, since they're not designed for DD.
 

Scott_650

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Apogee lists add-on avionics bay kits for BT50 thru BT70 sized rockets complete with sleds and hardware.
 

Scott_650

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Likely not low, but more of mid-power sized projects.
You really need minimal airframe space and radius to have room for the electronics and the battery.
And if you go high enough, you also need a GPS tracker, that takes yet more space and adds weight. Without a GPS tracker, I would mentally prepare to never see the rocket again after the inaugural launch. Next thing you know, C&D motors our inadequate.

Consider something along the lines of Aspire with an optimal DD avionics bay:

a
The Aspire uses 29mm motor mount tubes for the body, right? That should hold up to a reasonable charge going off. Launching one on an adapted 24mm BP motor as a DD rocket would be pretty nifty! An Estes D12 should easily lift the rocket, avbay, altimeter and associated recovery gear well over 1k feet...using just about any 29mm motor should get it really up there.
 

RalPh8

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You can absolutely fly dual deploy on those motors. Pretty much any kit with a coupler can be converted without much trouble. Even without one, you can always split the tube if the kit is long enough or just add on a converted payload bay.
That’s what I firgured. Just figured you guys would have some better answers than what I could think of.
 

RalPh8

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If you don’t want roll your own there are several vendors who have smaller add-on avionics bay kits - either separate payload sections or nose cone style. Unfortunately I can’t bring the nose cone bay vendor’s name to mind. Eggtimer has a nose cone mount for their new Apogee deployment altimeter. When Mach1 is back up and running after the move west they have multiple BT55 and BT60 kits that can be upgraded with an avionics bay. One of the members of my club (Gheem of The Rocketry Show podcast) does DD with BT60 based rockets pretty regularly - give him a shout on the TRS FB page, I’m sure he has some insight he’d share.
Appreciate it!
 

Zeke Johnson

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>>>------>

Build a fiberglass kit. It will handle the BP charge better than cardboard or paper.

Some come with an electronics bay option, even in 18mm.

I hear there is going to be a new vendor that sells top of the line fiberglass kits starting 3/1/21.

http://www.mach1rocketry.com/

Zeke
 

gtg738w

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>>>------>

Build a fiberglass kit. It will handle the BP charge better than cardboard or paper.

Some come with an electronics bay option, even in 18mm.

I hear there is going to be a new vendor that sells top of the line fiberglass kits starting 3/1/21.

http://www.mach1rocketry.com/

Zeke

Most of the Mach1 kits do come with split tubes and a coupler - also fiberglass. It is listed on the kit description. We’ve setup an 18mm Alien Interceptor for Dual Deployment, it’s a fantastic kit!

4DCFEEB4-A583-4B9D-A4FC-6F988F46E4A3.jpeg
 

afadeev

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The Aspire uses 29mm motor mount tubes for the body, right? That should hold up to a reasonable charge going off. Launching one on an adapted 24mm BP motor as a DD rocket would be pretty nifty!
Yes, it does, and yes, it will.
But even on the puniest E12 motor, Aspire will go north of 2K feet.
Throw in a slow-burning Apogee F10 in there, and you are looking at 5+K foot altitude. Zero chance you will see the apogee. Without a GPS tracker, it will be pure luck on whether or not you spot the chute/streamer on descent.

Other than that, it should be a fun flight.
 

heada

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Yes, it does, and yes, it will.
But even on the puniest E12 motor, Aspire will go north of 2K feet.
Throw in a slow-burning Apogee F10 in there, and you are looking at 5+K foot altitude. Zero chance you will see the apogee. Without a GPS tracker, it will be pure luck on whether or not you spot the chute/streamer on descent.

Other than that, it should be a fun flight.
H13 would push it north of 10k feet. (edit: yes, I know its no longer LPR, but.....2 miles on an Aspire!!)
 

RalPh8

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>>>------>

Build a fiberglass kit. It will handle the BP charge better than cardboard or paper.

Some come with an electronics bay option, even in 18mm.

I hear there is going to be a new vendor that sells top of the line fiberglass kits starting 3/1/21.

http://www.mach1rocketry.com/

Zeke
Just took a first look at mach1... dammit! Now I’m gunna have to spend more money! Wife is gunna be pissed. Supposed to be saving money for our child. lol
 

Scott_650

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Just took a first look at mach1... dammit! Now I’m gunna have to spend more money! Wife is gunna be pissed. Supposed to be saving money for our child. lol
But at least you have till 1 March to save up!
 

Zeke Johnson

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Most of the Mach1 kits do come with split tubes and a coupler - also fiberglass. It is listed on the kit description. We’ve setup an 18mm Alien Interceptor for Dual Deployment, it’s a fantastic kit!

View attachment 447365
Russ,

Why do you keep teasing us with that FS-SPORT?

We Want One! ...or two, or three, or...

Zeke
 

Neutron95

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The Aspire uses 29mm motor mount tubes for the body, right? That should hold up to a reasonable charge going off. Launching one on an adapted 24mm BP motor as a DD rocket would be pretty nifty! An Estes D12 should easily lift the rocket, avbay, altimeter and associated recovery gear well over 1k feet...using just about any 29mm motor should get it really up there.
The Aspire tubes are 29mm, but they're thin wall tubes that are much closer to the durability of Estes tubes, instead of something like Loc cardboard.
 

MetricRocketeer

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Hi everyone,

This thread caught my attention. I have been considering trying dual deployment, but I did not want to conflate that process with building a new high-powered rocket. I already have a nice, frequently flown Estes Firestorm, which as you know is an almost ready-to-fly low-powered rocket. So I have now started investigating DD using my Firestorm.

I went to the Apogee Components website, where I read and listened to Tim's highly instructive material. I learned a lot.

To begin with, here is what I think I understand:

You construct an avionics bay containing two ejection charges. The forward charge will cause the forward air tube containing the large, main parachute to separate. The aft ejection charge acts on the aft air tube containing the small drogue parachute. Actually, for small rockets, Tim suggested not to use a drogue at all -- and instead just to let the rocket drop until the main parachute slows the descent.

But here is what I don't understand:

Why do you need an aft ejection charge? Won't the ejection charge of the rocket motor cause the aft air tube to separate?

Thank you.

Stanley
 

Scott_650

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Hi everyone,

This thread caught my attention. I have been considering trying dual deployment, but I did not want to conflate that process with building a new high-powered rocket. I already have a nice, frequently flown Estes Firestorm, which as you know is an almost ready-to-fly low-powered rocket. So I have now started investigating DD using my Firestorm.

I went to the Apogee Components website, where I read and listened to Tim's highly instructive material. I learned a lot.

To begin with, here is what I think I understand:

You construct an avionics bay containing two ejection charges. The forward charge will cause the forward air tube containing the large, main parachute to separate. The aft ejection charge acts on the aft air tube containing the small drogue parachute. Actually, for small rockets, Tim suggested not to use a drogue at all -- and instead just to let the rocket drop until the main parachute slows the descent.

But here is what I don't understand:

Why do you need an aft ejection charge? Won't the ejection charge of the rocket motor cause the aft air tube to separate?

Thank you.

Stanley
The entire concept of using separate ejection charges and an altimeter/flight computer is to more precisely control the recovery process. It allows the rocket to fall with minimal drift after the first event under a streamer, drogue or just the separated rocket and then have the main chute open later. All under the control of the altimeter at set altitudes determined by the rocketeer. The delays built in to any motor whether their adjustable or not are not as exact as using an altimeter to trigger the charge.
 

MetricRocketeer

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Hi Scott 650 and anyone else,

Thank you for your response.

Then let me please first get this issue nailed down. Whether or not it's a good idea, would the motor ejection charge cause the aft air tube to separate from the forward air tube?

Stanley
 

heada

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Hi Scott 650 and anyone else,

Thank you for your response.

Then let me please first get this issue nailed down. Whether or not it's a good idea, would the motor ejection charge cause the aft air tube to separate from the forward air tube?

Stanley
Normally you would either use a motor with no ejection charge or a motor with a delay longer than the estimated apogee.

Plugged motors, those without an ejection charge, are normally labeled with a P rather than a delay. For example a C11-P

For a motor with the charge, pick a delay longer than expected such as if you expect apogee at 6 seconds, rather than use a -6 motor, use a -8 motor.
 

MetricRocketeer

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For a motor with the charge, pick a delay longer than expected such as if you expect apogee at 6 seconds, rather than use a -6 motor, use a -8 motor.
That makes sense. And therefore, to simplify the dual-deployment process, I think that this would be a good method, although I acknowledge that you would be sacrificing some precision.

Thus, allow me to summarize my argument:

For dual deployment with low-powered rockets, a feasible method is to use just the forward ejection charge. Rely upon the rocket motor to separate the aft air tube from the forward air tube so as to deploy the drogue parachute or the drogueless recovery. Then, as long as the rocket goes high enough, the altimeter or flight computer would cause the main parachute to deploy at the predetermined altitude.

I am asking readers to please weigh in on this proposal. Would this work, or am I way off base?

Thank you.

Stanley
 

heada

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Yes, that should work. You're sacrificing precision deployment at apogee for simplicity of using motor ejection. Most pick a hybrid approach by using both. You get the precision of using electronics for the apogee event and use the motor ejection as a backup in case the electronics don't fire.
 

Nick Hutton

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Unless you make your own altimeter, most are going to have a drogue channel as well as a main. So you’d have to put something on the drogue channel or your main wouldn’t fire. Even if you used a single channel apogee only, it wouldn’t be any good for deploying a main at a separate altitude.
 

RalPh8

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Unless you make your own altimeter, most are going to have a drogue channel as well as a main. So you’d have to put something on the drogue channel or your main wouldn’t fire. Even if you used a single channel apogee only, it wouldn’t be any good for deploying a main at a separate altitude.
You can just putting a connecting jumper wire from one terminal on the drogue channel to the other. Then main should still fire.
 

prfesser

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You can just putting a connecting jumper wire from one terminal on the drogue channel to the other. Then main should still fire.
Would a resistor be better for this? Could the altimeter be damaged by having a jumper of essentially zero resistance across the drogue channel? I'm not terribly altimeter-savvy...
 

RalPh8

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Would a resistor be better for this? Could the altimeter be damaged by having a jumper of essentially zero resistance across the drogue channel? I'm not terribly altimeter-savvy...
Maybe. I’m not an electrical engineer. Worse case scenario you can just use an ematch to nothing.
 
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