First timer with Dual Deploy

[bobtheshortstop]

Hello all, I recently certified level 2 and I finally want to get into building rockets with dual deployment. Except I have no idea where to start. I understand how it works and how beneficial it is. But as far as choosing the right altimeter, construction steps of an avionics bay, programming, I am completely dumbfounded. I've gone onto websites and read manuals for altimeters, read as much as I could find but I'm still confused on how I should start. I have a couple level 2 rockets sitting aside waiting to be built but I would like to start with perhaps a smaller kit. I'm thinking either a Madcow or Wildman 2.1" kits that comes as dual deploy standard.

My questions are:

What is a good first time altimeter to buy?
Where can I find construction tips on how to build an avionics bay?
Where can I find some tips on programming?

Any links or advice is appreciated.

 

[waltr]

Many good Altimeters. I use Eggtimer since building them (soldering small parts) is easy for me.
The missile works RRC2 is a good altimeter.

Start with simple easy to set up DD altimeter that does not need complex programming. Just setting Main deploy altitude, connect eMatches and go.

Start with smaller, E-G motor, rocket to learn DD.
I run DD on 24mm up to 2.6" BT rockets with C to G motors, all NAR class 1.
Best if you can see the rocket at apogee to watch deployment take place. Also smaller rocket is safer and cost less when something doesn't work.

This forum is good for ebay building and altimeter usage.
Do searches then read.

 

[SecondRow]

There are many different options for altimeters, bay setup, materials to use…etc.

Here’s a thread that might help. It can give you some ideas on how to build the bay. https://www.rocketryforum.com/threads/the-avionics-bay-thread-post-your-photos.156649/

 

[DaHabes]

First I started with a JL Chute Release, which I intend to use for a low and slow L2 certification (keep it simple and get the L2 cert so I can use the bigger motors). I've also built and used an Eggtimer Apogee to learn the soldering stuff and work with an altimeter and BP. Next I've flown (once, so far) an Eggfinder Mini to start learning and using tracking. My next step is to use SMT Designs and Badass Rocketry nose cone deployment/tracker AV-Bays to expand to dual deploy (with motor ejection backup) and tracking. I also have a Featherweight GPS (yet to fly) for those rockets that start going way out of sight. After that it's traditional dual deploy in a standard AV-Bay configuration with either an SMT Designs or Badass Rocketry tracker AV-Bay in the nose cone. As I progress up the chain, I intend to use bigger motors. Fitting into the progression somewhere are either scratch builds or kits with larger diameter motors (54mm and 75mm). It's baby steps all on the path to L3.

 

[Exactimator]

Missileworks RRC2 and Perfectflight CF are both ready out of the box and can be run off a 9v battery. Bkth altimeters can have their parameters changed as you get more comfortable.

There are videos on Apogee Rocketry's website on how to set up av bays. There's also a thread here with av bay pics. I'll get some links.

https://www.rocketryforum.com/threads/the-avionics-bay-thread-post-your-photos.156649/
https://www.apogeerockets.com/Intro-to-Dual-Deployment?pg=quickside
https://www.apogeerockets.com/Advanced_Construction_Videos/Rocketry_Video_26

 

[bobtheshortstop]

Thanks for all the replies and advice! I'm probably gonna go with a cheap madcow 2.6" kit and purchase their avionics bay kit. Pair that with a missileworks altimeter... Probably test fly with a smaller G motor, then work with it a little bit. I have a Composite Warehouse Airstrike 354 coming tomorrow, can't wait to start the build and fly with a K185... Definitely wanna have dual deploy figured out for that build.

 

[teepot]

I have a Missile Work RRC2 and like what has been said, it works right out of the box. I also have a RRC3 with the LCD interface. I like it because it has 3 pyro channels. I set it for 1 for drouge with motor back up and 2 for the min. A primary and back up. With the LCD interface it is very easy to program. I also have a JLCR that goes in single deploy rockets. I like that a lot too.

 

[b.wieting]

I rebuilt my MiniMagg, inserting a shortened LOC eBay. It worked very nicely.
John Coker's website http://www.jcrocket.com is an excellent resource.

 

[waltr]

Thanks for all the replies and advice! I'm probably gonna go with a cheap madcow 2.6" kit and purchase their avionics bay kit. Pair that with a missileworks altimeter... Probably test fly with a smaller G motor, then work with it a little bit. I have a Composite Warehouse Airstrike 354 coming tomorrow, can't wait to start the build and fly with a K185... Definitely wanna have dual deploy figured out for that build.

Should be a good kit for DD learning.

My recommendation to keep apogee low has two reasons:
1- to see the drogue and main events to ensure they did work.
2- keep a visual on flight for recovery.

Once it starts going past limits of visual tracking GPS of RFD is need to find the rocket.
I suggest perfectly DD first. do multiple flight to lower apogee to ensure system and your procedures are correct. There are a lot more things that can go wrong doing DD.
Then add GPS/RFD with practice tracking before flying too high.

I had my first flight with GPS this past
Saturday. 1.6" LOC IRIS on F67W to 500'. Everything did work. Next is G76 which should go to 1300'.
When I get L1 cert an H will take it out of sight so both DD and GPS must work if I'm to recover it.


Good links posted above to learn about DD.
Please do keep us posted on your progress.

 

[Bat-mite]

Agree with the post above. You want to be able to see the pieces separate. Otherwise, if you find it in a heap on the ground, you won't know what happened.

But, let me encourage you that DD is simpler than it sounds/looks. And I must say, I have learned more from walking up to someone and asking them to show me their setup then I have by reading. Rocketeers like to talk about their birds, so a quick "Do you mind showing me your DD configuration?" will probably get an enthusiastic response.

Heck, I don't know where you live, but if it's anywhere near Maryland, you can come to my house.

 

[EPflyer]

Start with smaller, E-G motor, rocket to learn DD.
I run DD on 24mm up to 2.6" BT rockets with C to G motors, all NAR class 1.
Best if you can see the rocket at apogee to watch deployment take place. Also smaller rocket is safer and cost less when something doesn't work.

I agree with waltr. This is the path I took with my entry to dual deploy. I designed my own rocket using BT60 tubes and a 24mm motor mount. The rocket is about 35" in length. I purchased a bt60 AV bay from Apogee Components. The altimeter is an Eggtimer Quark.

I have 6 flights on the rocket,
Flight 1 awful, shock cord too short, AV bay separated from booster. Main fired at high velocity and shredded the plastic chute. minor damage.

Flight 2 so-so, 12" Drogue too large, main deployed but did not inflate, hard landing but no damage.

Flight 3 perfect, oh yeah, I thought I knew everything.

Flight 4 awful, too much dog barf prevented drogue from exiting booster. Main did not fire due to bad igniter. Free fall from 1470' broke 1 fin.

Both flights 5 and 6, repaired rocket flew perfect over 1500' on Aerotech E18 reloads.

I am still learning with every flight. I have a LOC Deployer on the way for my next DD rocket. it has a 29mm motor tube in a 3" airframe. I plan to use an Eggtimer Quantum with a telemetry module.

 

[bobtheshortstop]

Should be a good kit for DD learning.

My recommendation to keep apogee low has two reasons:
1- to see the drogue and main events to ensure they did work.
2- keep a visual on flight for recovery.

Once it starts going past limits of visual tracking GPS of RFD is need to find the rocket.
I suggest perfectly DD first. do multiple flight to lower apogee to ensure system and your procedures are correct. There are a lot more things that can go wrong doing DD.
Then add GPS/RFD with practice tracking before flying too high.

I had my first flight with GPS this past
Saturday. 1.6" LOC IRIS on F67W to 500'. Everything did work. Next is G76 which should go to 1300'.
When I get L1 cert an H will take it out of sight so both DD and GPS must work if I'm to recover it.


Good links posted above to learn about DD.
Please do keep us posted on your progress.

Thanks for all the tips waltr. That's smart already knowing how to fly with avionics and GPS before you certify. I've just been doing it the old fashioned motor ejection way since day one lol. I ordered a couple of missileworks RRC2+ altimeters last night. Just gotta pick out the kit now.

 

[Zbench]

Another plug for Eggtimer. Can’t tell you how satisfying it is to build one of these from a bag of parts and then put it in a rocket you also built.

The quark offers basic DD and has everything you need except a soldering iron. It is only $20. Stepping up to the quantum gets a ton more features including configuring it via WiFi. It’s $40.

After building a few you can even step up to the TRS which is an Altimeter and GPS tracker all in one package. It is $90. You will need the ground station receiver to go with it which is also fun to build.

The support Cris provides through his website and email is second to none and nothing comes close to the innovation his products provide at the price point he offers them at.

 

[JohnCoker]

Here are some videos I made. They may be a bit basic for you, but who knows.

 

[bobtheshortstop]

Here are some videos I made. They may be a bit basic for you, but who knows.

John, thank you for these videos! Quite simple to understand.

 

[OzHybrid]

As I'm a Tripoli member this advice will be based on that and I'll assume you are a member. Go to the members list, find all the people in your area certified L2 or higher. Go to your club, locate those people and talk to them. Most will be more than happy to show you their deployment methods, AV bays, talk about chute sizing, chute types and electronics. Some will have favourites. Ask them why. Ask what issues they have experienced. Make notes.
You don't need to rush unless there is a reason. This will get you advice and allow you to match your skill/tool set. You might even find a mentor.
The NAR process will I'm sure be similar. Come back and ask again, but you'll probably only be getting people to confirm what you're thinking by then.
Regards
Norm

 

[debonairbear]

Same situation as OP, but I've got the gear and rocket already built.

All the videos I'm seeing online are using shopvacs to simulate altitude. Without that, do you have any recommendations to ground test the size of the BP charge?

 

[Bat-mite]

Same situation as OP, but I've got the gear and rocket already built.

All the videos I'm seeing online are using shopvacs to simulate altitude. Without that, do you have any recommendations to ground test the size of the BP charge?

Yes. I never use shop vacs. I test my altimeters in a jar with a syringe. More on that later.

As far as testing the actual rocket deployments, here's what I do:

1. Use an ejection charge calculator to get a starting level of BP.
2. Load the rocket in flight condition. Sure, you can substitute towels for chutes, etc. But I want mine to be exactly like it will be in flight, as much as possible.
3. Make sure there is a motor in the MMT (otherwise, all the ejection pressure goes right out the back).
4. Prior to test, I detach the leads from the altimeter and run them out one of the sampling ports in the switch band.
5. Hook up an Estes launch controller to the leads.
6. Have a moving blanket on the ground in front of the rocket to minimize scuffing, dirt, etc.
7. Ignite the e-matches with the Estes controller. One caveat, since the Estes controller has to light a little flashlight bulb with its continuity test, it has to send a lot of current out for its continuity test. Thus, the continuity test will probably ignite the BP before you ever press the launch button. So be prepared for that.
8. Do it in flight order. Eject the forward section from the booster; then hook the leads to the main and eject the NC. Just like in flight.
9. You are looking for the chutes to come completely out of the tubes without overstressing your harnesses. If the harness causes kick-back, too much BP. If the chutes don't get all the way out of the tube, too little.
10. The chute does not need to do anything fancy. In the air, once it clears the tube, the wind and gravity will do the rest.
11. And of course, make sure all shear pins break. If not, more BP.
12. On your first launch of that rocket, watch what happens at the events. If the harness is causing snap-back or kick-back, remove a little BP next time. Since the ground creates friction against the tubes, you won't need quite as much BP when the rocket is in the air.

 

[Antares JS]

Same situation as OP, but I've got the gear and rocket already built.

All the videos I'm seeing online are using shopvacs to simulate altitude. Without that, do you have any recommendations to ground test the size of the BP charge?

I do two different deployment tests, neither of which requires a shop-vac. Note that I own a Raven3 and three Stratologgers.

Before doing either test, I do a check. Both of the altimeter types I own are able to stream live data to a PC, so I hook up the altimeter to the computer and check the readouts.

-Are any of the data readouts way out of whack?
-Does the pressure drop slightly when I lift the altimeter up and rise when I lower it to the floor?
-In the case of the Raven, is it reading 1g on the accelerometer in the correct orientation?

By doing this check I know the sensors are working.

For the first actual test, your altimeter should have some kind of test mode where it will set off e-matches. Wire up e-matches of the same type you are going to use during flight and run the test mode. Make sure it sets off the e-matches in the sequence it is supposed to. The Raven3 does this test especially well as the Featherweight software will actually feed the Raven simulated flight data, so you can watch the simulated altitude and make sure the e-matches blow on cue. By doing this you know that this altimeter and this battery will set off these e-matches.

With that done, I know my altimeter is good.

The other test for charge sizing is done without the altimeter. I set up an ejection charge and rather than hooking the leads up to an altimeter, I run the leads out one of the bleeder holes in the e-bay. Once the charge is set up, pack the parachute and harness the same way you will for the actual flight. Lay the rocket on the ground, putting the rear end up against something solid and prop it up so that the section to be separated is completely off the ground and not touching anything. Once you're set up, hook up an Estes controller to the leads, make sure neither end of the rocket is pointed at anyone, and use the controller to set the charge off. You want a vigorous separation that pushes/pulls all the laundry out. If it doesn't separate or separates weakly (like if the nose pops off but flops to the ground while the parachute remains inside), repeat the test with more powder until you get the aforementioned vigorous separation. Fly with the amount of powder that got you the vigorous separation.

 

[Bat-mite]

Altimeter testing. Always test brand new altimeters, altimeters you built yourself, and altimeters that have experienced a hard landing.

I was fortunate, years ago, to purchase an Adept Altimeter Testing Kit. But you can make your own.

• A mason jar with a screw on lid.
• A large syringe.
• A rubber tube.
• Two LEDs and resistors.
• 9V battery connector.
• 9V battery.

Drill a hole in the lid the size of the rubber tube. Drill a smaller hole for the wires to come out.

You'll need wires for the main charge (2), drogue charge (2), battery (2). Make these about a foot long, and run them through the small hole in the lid. Seal the hole with epoxy or clay or something.

Attach the inside side of the wires to the altimeter. Insert the altimeter into the jar and screw on the lid.

Insert the tube into the hole in the lid. If it is leaky, epoxy it in there so that it is airtight.

Outside, attach the battery wires to the battery connector. Attach the LEDs and resistors inline to the main and drogue wires. (For your altimeter, find out how much current it puts out, and make sure the resistance of the LED/resistor combo produces the amount of resistance to get that current to the LED.)

Once everything is all hooked up, connect the battery and let the altimeter go through its prelaunch sequence.

Rapidly draw back the syringe to simulate liftoff and upward velocity.

Stop drawing at the top of the syringe. This will simulate apogee, and the drogue LED should light.

Slowly lower the plunger back into the syringe to simulate descent.

When the programmed main deployment "altitude" is reached, the main LED should light.

After flight, your altitude should beep out its "altitude" for that "flight." You can even download it and graph it.

 

[debonairbear]

Holy cow! I love these suggestions! So much testing to take care of before the next launch. Thank you!

I'm glad I asked. I was ignorantly going to jump to later steps and skip some of these that make complete sense.

 

[Andrew Brown]

There are a lot of suggestions for perfecting with smaller rockets. I took the opposite approach. Having a 4" electronics bay is luxurious vs having to keep everything tiny. The other approach I took was to simulate dual deploy by ejecting the main out of the booster at apogee (~1000ft) with the electronic deploy setting for drogue (keeping motor as backup timed for about 2 seconds after apogee), then firing the main charge at 500 ft from an empty payload bay. This simply separates the nose from the payload. This approach allows one to fully simulate DD while having the comfort of single deploy. If the altimeter or ematch didn't work, or if the charge was incorrect, the motor would still eject the main. No harm done.