Rocket and Electronics for Airstarts and DD? Recommendations?

[ThirstyBarbarian]

I’d like to start experimenting with airstarts, and along with that, electronic deployment and dual deployment.

I’m looking for recommendations for a rocket with a cluster mount, with a central motor and 2 to 4 outboards. I am an L2, so the combined total of motors can be in the L2 range, but I’d like this rocket flyable on just a single L1 central motor if possible, so nothing huge! I’m not into high-performance, high-altitude flights, so it’s fine if the rocket is fat, as long as it’s not too heavy. I’d like the rocket to have a full dual deploy setup with everything needed for an electronics bay.

In addition to the rocket, I need the flight computer. This is the most intimidating and least attractive part of the project for me. I know some people like fiddling with electronics and enjoy that aspect of the hobby, but that’s not me. I’ve got my L2, but the closest I’ve come to dual deploy flights is using a Jolly Logic Chute Release, which is very consumer friendly, easy to use straight out of the box, hard to screw up. I’ve always done motor eject, and the reason I’ve avoided electronic eject is my aversion to the electronics. To me, this is going to be a necessary evil and means to an ends for the flights I want to fly, so I’d like it to be as easy as it can be. So with that said, I’d like a recommendation for a system to initiate (or inhibit) airstarts and to fire the drogue and the main — one which is easy to set up and easy use.

Thanks!

 

[rharshberger]

There are several options Thirsty....

Eggtimer Proton (kit, but Conman13 still does the assembly last I heard)

Eggtimer Quantum (again a kit) but does airstarts, no tilt inhibit afaik

Marsa TiltGadget needs a Marsa54 Altimeter iirc

Featherweight Raven

Missleworks PET2+, no tilt lockout but pretty easy to use

Missleworks RRC3, no tilt lockout but 3rd output can be used for airstarts.

Altus Metrum also has a altimeter that will do airstart and tilt inhibit/lockout

Of these I own the PET2+ (haven't flown yet), Eggtimer Quantum (2 flights, pretty easy to set up but still may take a bit of practice), Missleworks RRC3 (flown lots as a DD altimeter never for airstarts), Eggtimer Proton (just got shipping confirmation yesterday....). All will work.

As for the rocket, how about a Loc Warlock, Loc Doorknob, Loc Big Cletus, Loc Goblin 7.5" with a cluster mount (the Loc Boys will make them for you on request).

 

[blackjack2564]

Part!

Thirsty....I think after knowing you for many years on this forum....I understand exactly where you are coming from.
You want simplicity without complication. Ease of use & concentrate on the flying.

Here's the rub; no experience in DD. Sooo that being said my take is fix you up with as simple to use electronics as possible.
Am I on the right path so far???

You will need something to fire the airstarts & something for DD . I would go with 2 separate units, rather than one 'does it all'. Reason...fewer settings to deal with and possibly screw up. Bear in mind this is based purely on YOUR experience not the general public guys so don't start the hissy fits guys. Think of Thirsty's situation not your own!

Lets start with function. Airstarts can be based from central motor ignition or shutdown, and you can go with fire [airstarts] at burn out or add time delay to burn out. Such as central burns out + 2 seconds...then fire outboards.

The Pet-2 timer has accelerometer based function. DEFAULT is fire at motor burnout. PERFECT for first time learning, install it and hook up motor igniters. No need think about anything. You can add larger battery [9v default] to pyro side if need be for large clusters.

There may be other units out there with default setting like this I just don't know, but this is what I recommend for learning without risk.
Because you are using a separate unit for AS [airstarts] you can mount it in fincan near motors, so you don't need to route wire up to av-bay and through recovery gear. Another pitfall avoided for a beginner. No need to hook up to computer to set things...just install and go for now....

Got go eat turkey will pick up later on altimeter and rocket.....Part 2 coming

 

[Mr G]

Thirsty, I'm drinking from the same Kool-Aide hose (or whatever one drinks on Thanksgiving) as there are several projects in the build pile with multiple motors. I'm even considering "air start" of outboard boosters at launch on a separate circuit for a more reliable start.

Crazy Jim has been a go-to guy so far so I trust what he offers will be sage advice. And then we can go crazy at a future TCC or LUNAR launch, maybe not a multi-multi-motor drag race though

 

[blackjack2564]

Part 2

First I should mention 45.00 for the Pet-2 very reasonable.
Altimeters:
For an altimeter something so simple, you just hook up charges and go. No computer program or LED panel needed to set anything.
Simple cheap very easy to use & goof proof. Stuff like auto mach immune [no need to explain cause it's in there. Apogee delay [when using more than 1 altimeter] someday you may need this.
Simple to change main deploy altitude. Needed for different size chutes on different size rockets.
Large chutes need longer to open, so you set altimeter to fire main charge higher.
I'm thinking 45-55.00 about as cheap as you can get, without building a kit.

Missleworks RRC2+ and Perfectflight CF are ones I like, Both will work on a variety of batteries also...9v & LiPo.
I'm sure there are others, but these 2 I have been using for many years and they just plain ALWAYS work. No frills or fuss.
The RRC2 has settings printed on board and switches to change them. [altitude]
PerfectFlite will beep out the settings and if desired you can download data to computer. That will require additional data cable 35.00.
You do NOT need tiltometers and various other sundries to get started in this. We simple use enough thrust the flight is straight and fire airstarts before the rocket begins it's gravity turn.[arcing over] all quite simple with a few calculations when picking motors based on weight of rocket.

Going this route will also give you the comfort of being able to use your Jolly Logic at first and transitioning into full blown Dual. Deploy with electronics & charges.
Go here for detailed installation of av-bays & altimeters in great depth for first timers: Look at all Av-bay and sled stuff.
https://www.rocketryforum.com/threads/how-to-build-a-stock-3in-darkstar-cj-step-by-step.55019/
These techniques will work on any size bays..just upscale threaded rods and hardware.

Use motor eject on central and your JL. on first few flight. Have altimeter in the av-bay with charges. Best of both worlds.
When you feel comfortable with functionality of altimeter ...just use that, no longer need the JL.
Since you will be using a separate timer to fire outboards, anything goes for altimeter use!

Picking a rocket is a bit more challenging.
There aren't that many cluster kits out there.
First one comes to mind is the LOC Magnum. Central 54 with 2 29mm outboards. 5.5 in diameter kit. Easily can fly on J-350 [38mm] and a variety of 29mm.
Then the PML Ultimate Endeavor which is 6in diameter and has 54 central with 3- 38mm outboards.
My personal favorite due to so many motor options, however not within your specs, because I don't think you could use many 38's central to lift. It would need the largest 38 motors which cost as much as small 54's.

I'm sure others will have some rocket choices i'm not aware of.
At this point in my flying career I design my own.
So after all the above mumbo-jumbo...I have picked electronics for you that cost under 100.00 [for both] and you just hook them up, out of the box, no need to figure out any fancy settings.
Hopefully this will help you a bit and now let the Questions begin...lol

Maybe some more detail on what size rocket you are looking for and what motors you want to use [size wise]
I can get into how to figure lift size of motors and delay times... how to... a bit later into the discussion, after some basic designs are made first.

 

[dshmel]

...
I'm sure others will have some rocket choices i'm not aware of.
...

Madcow released the Trinity which is 54mm in the center with a (3) 29mm cluster.

 

[blackjack2564]

I forgot to mention the Pet-2 timer has another channel [2 timers] which you can use for air starting/staging or back-up for DD. apogee.

Trinity looks very nice.

 

[BrAdam]

Don’t want to derail or take this too far off topic from Thirsy’s original questions but I am looking to take the same next step as him.

Question for CJ is where do you mount the timer and how do you wire the air starts? Do the wires break somewhere during deployment?

 

[ThirstyBarbarian]

There are several options Thirsty....

Eggtimer Proton (kit, but Conman13 still does the assembly last I heard)

Eggtimer Quantum (again a kit) but does airstarts, no tilt inhibit afaik

Marsa TiltGadget needs a Marsa54 Altimeter iirc

Featherweight Raven

Missleworks PET2+, no tilt lockout but pretty easy to use

Missleworks RRC3, no tilt lockout but 3rd output can be used for airstarts.

Altus Metrum also has a altimeter that will do airstart and tilt inhibit/lockout

Of these I own the PET2+ (haven't flown yet), Eggtimer Quantum (2 flights, pretty easy to set up but still may take a bit of practice), Missleworks RRC3 (flown lots as a DD altimeter never for airstarts), Eggtimer Proton (just got shipping confirmation yesterday....). All will work.

As for the rocket, how about a Loc Warlock, Loc Doorknob, Loc Big Cletus, Loc Goblin 7.5" with a cluster mount (the Loc Boys will make them for you on request).

Thanks for the list of altimeters — looks like lots of options!

For your Eggtimer Quantum, have you used the WiFi interface? Is that something you can access with an iPhone? For any of the Eggtimer products, I’d need someone to build the kit for me.

I’ll take a look at the other models you mentioned as well. Thanks!

 

[ThirstyBarbarian]

Part!

Thirsty....I think after knowing you for many years on this forum....I understand exactly where you are coming from.
You want simplicity without complication. Ease of use & concentrate on the flying.

Here's the rub; no experience in DD. Sooo that being said my take is fix you up with as simple to use electronics as possible.
Am I on the right path so far???

You will need something to fire the airstarts & something for DD . I would go with 2 separate units, rather than one 'does it all'. Reason...fewer settings to deal with and possibly screw up. Bear in mind this is based purely on YOUR experience not the general public guys so don't start the hissy fits guys. Think of Thirsty's situation not your own!

Lets start with function. Airstarts can be based from central motor ignition or shutdown, and you can go with fire [airstarts] at burn out or add time delay to burn out. Such as central burns out + 2 seconds...then fire outboards.

The Pet-2 timer has accelerometer based function. DEFAULT is fire at motor burnout. PERFECT for first time learning, install it and hook up motor igniters. No need think about anything. You can add larger battery [9v default] to pyro side if need be for large clusters.

There may be other units out there with default setting like this I just don't know, but this is what I recommend for learning without risk.
Because you are using a separate unit for AS [airstarts] you can mount it in fincan near motors, so you don't need to route wire up to av-bay and through recovery gear. Another pitfall avoided for a beginner. No need to hook up to computer to set things...just install and go for now....

Got go eat turkey will pick up later on altimeter and rocket.....Part 2 coming

Thanks for taking the time on this, both Part 1 and 2! You have it exactly right — I want it simple!

I’m open to the 2 units approach if that will simplify things. If the PET2 works out of the box in default configuration for basic airstarts, that sounds good to me. If I do want to program it for something other than default, how is the interface?

Not too long ago, I saw a thread in which someone was putting their airstart timer in a spare motor tube in a cluster mount. Is the PET2 something I could fit into a module that would slide into a 29 or 38mm motor tube? If so, then instead of a new rocket, I might think about modifying my existing Warlock. I could add 2 motor tubes for outboard motors and another for the airstart timer. This would be an easy way to modify the existing rocket, if it would work. And I agree I’d like to avoid routing the wires all the way from the motors up through the recovery gear to the forward end.

 

[ThirstyBarbarian]

Part 2

First I should mention 45.00 for the Pet-2 very reasonable.
Altimeters:
For an altimeter something so simple, you just hook up charges and go. No computer program or LED panel needed to set anything.
Simple cheap very easy to use & goof proof. Stuff like auto mach immune [no need to explain cause it's in there. Apogee delay [when using more than 1 altimeter] someday you may need this.
Simple to change main deploy altitude. Needed for different size chutes on different size rockets.
Large chutes need longer to open, so you set altimeter to fire main charge higher.
I'm thinking 45-55.00 about as cheap as you can get, without building a kit.

Missleworks RRC2+ and Perfectflight CF are ones I like, Both will work on a variety of batteries also...9v & LiPo.
I'm sure there are others, but these 2 I have been using for many years and they just plain ALWAYS work. No frills or fuss.
The RRC2 has settings printed on board and switches to change them. [altitude]
PerfectFlite will beep out the settings and if desired you can download data to computer. That will require additional data cable 35.00.
You do NOT need tiltometers and various other sundries to get started in this. We simple use enough thrust the flight is straight and fire airstarts before the rocket begins it's gravity turn.[arcing over] all quite simple with a few calculations when picking motors based on weight of rocket.

Going this route will also give you the comfort of being able to use your Jolly Logic at first and transitioning into full blown Dual. Deploy with electronics & charges.
Go here for detailed installation of av-bays & altimeters in great depth for first timers: Look at all Av-bay and sled stuff.
https://www.rocketryforum.com/threads/how-to-build-a-stock-3in-darkstar-cj-step-by-step.55019/
These techniques will work on any size bays..just upscale threaded rods and hardware.

Use motor eject on central and your JL. on first few flight. Have altimeter in the av-bay with charges. Best of both worlds.
When you feel comfortable with functionality of altimeter ...just use that, no longer need the JL.
Since you will be using a separate timer to fire outboards, anything goes for altimeter use!

Picking a rocket is a bit more challenging.
There aren't that many cluster kits out there.
First one comes to mind is the LOC Magnum. Central 54 with 2 29mm outboards. 5.5 in diameter kit. Easily can fly on J-350 [38mm] and a variety of 29mm.
Then the PML Ultimate Endeavor which is 6in diameter and has 54 central with 3- 38mm outboards.
My personal favorite due to so many motor options, however not within your specs, because I don't think you could use many 38's central to lift. It would need the largest 38 motors which cost as much as small 54's.

I'm sure others will have some rocket choices i'm not aware of.
At this point in my flying career I design my own.
So after all the above mumbo-jumbo...I have picked electronics for you that cost under 100.00 [for both] and you just hook them up, out of the box, no need to figure out any fancy settings.
Hopefully this will help you a bit and now let the Questions begin...lol

Maybe some more detail on what size rocket you are looking for and what motors you want to use [size wise]
I can get into how to figure lift size of motors and delay times... how to... a bit later into the discussion, after some basic designs are made first.

Thanks again for all the info.

I’ve taken a look at the 2 altimeters you mentioned, and it looks like the RRC2+ would be about the simplest to use.

I’m starting to lean towards modifying my existing Warlock. I have a head-end altimeter bay kit for the NC that I haven’t set up yet. I could use the altimeter to pop the nose cone at apogee and use the Jolly Logic to release the main.

For now, the main reason I feel like I need the electronic deployment is in case the outboard airstarts don’t light. I want the ejection to occur at apogee either way. I’m not planning on very high flights at this point, so it’s mostly about ensuring against crashes if the airstarts fail.

 

[ThirstyBarbarian]

Thirsty, I'm drinking from the same Kool-Aide hose (or whatever one drinks on Thanksgiving) as there are several projects in the build pile with multiple motors. I'm even considering "air start" of outboard boosters at launch on a separate circuit for a more reliable start.

Crazy Jim has been a go-to guy so far so I trust what he offers will be sage advice. And then we can go crazy at a future TCC or LUNAR launch, maybe not a multi-multi-motor drag race though

I’m looking forward to seeing what you come up with!

For me, this is working toward a far-in-the-future sci-fi rocket with motors in outboard pods (of course)! I’ve seen someone else try to light all those outboard motors on the pad, and it ended ugly. I think the best way to light outboards is after the rocket is on its way on a strong central motor, so I want to get some practice before I build a special rocket that would rely on airstarts.

 

[ThirstyBarbarian]

Don’t want to derail or take this too far off topic from Thirsy’s original questions but I am looking to take the same next step as him.

Question for CJ is where do you mount the timer and how do you wire the air starts? Do the wires break somewhere during deployment?

Feel free to ask your questions in this thread! You may have questions I didn’t think to ask.

I was looking at someone’s airstart setup at a launch in October. I didn’t get a lot of details, but it looked like he had a type of pull-apart connnector that would break loose on ejection.

What CJ was suggesting is to use a timer to light the airstarts, and to have it mounted in the fin can. That way you don’t need to route the wires to a forward altimeter. Then use a separate altimeter mounted in the forward av bay for deployment. I’m liking that idea.

 

[ThirstyBarbarian]

Here’s the thread I mentioned earlier about airstart timers installed in motor mount tubes. https://www.rocketryforum.com/threads/timer-modules-for-airstarts.148829/

I thought it was an interesting idea, but I thought it might make sense to buy just one altimeter for triggering both the airstarts and the electronic deployment. But CJs suggestion that it might make more sense to use 2 separate devices makes me think this might be an easy way to modify my existing Warlock for the airstart timer. It’s probably easier than cutting a door into the existing fin can, right?

The built Warlock has a central 38mm. I could drill holes for 2 outboard motors on opposite sides of the central 38. And then drill a separate hole for the airstart module.

 

[BrAdam]

Here’s the thread I mentioned earlier about airstart timers installed in motor mount tubes. https://www.rocketryforum.com/threads/timer-modules-for-airstarts.148829/

I thought it was an interesting idea, but I thought it might make sense to buy just one altimeter for triggering both the airstarts and the electronic deployment. But CJs suggestion that it might make more sense to use 2 separate devices makes me think this might be an easy way to modify my existing Warlock for the airstart timer. It’s probably easier than cutting a door into the existing fin can, right?

The built Warlock has a central 38mm. I could drill holes for 2 outboard motors on opposite sides of the central 38. And then drill a separate hole for the airstart module.

Thanks. Was hoping to pick up the new LOC VII and start to do clustered airstarts. I fly out of Bong in WI so will have to pick Eric C’s brain a bunch too along with reading that post and other info from CJ.

 

[ThirstyBarbarian]

Thanks. Was hoping to pick up the new LOC VII and start to do clustered airstarts. I fly out of Bong in WI so will have to pick Eric C’s brain a bunch too along with reading that post and other info from CJ.

That LOC VII looks like a very cool and versatile rocket. I love the LOC kits. Right mow I’m short of rocket storage space, so I’m leaning toward modifying my existing LOC Warlock. If I had the room, I’d be looking at adding a big LOC for this airstart rocket.

 

[Wayco]

I used the PET-2 timer to start all four of the outboards on "Tweety Bird". I went over the settings on it with Jim Amos, he is a great guy to work with and pretty easy to get a hold of. I won't say the programming is easy, but with his help I managed to get all the motors lit on time. My PET-2 was mounted directly above one of the motor mount tubes with access through a little door. Jim advised me to use a standard 9v battery, so I replaced the LiPo in the picture. We also discovered that mounting it with the X axis pointing up is necessary for it to operate correctly. I think you can program it to operate in three different positions, but mine was mounted upside down in the picture.

I mounted terminal blocks on the bottom of the aft centering ring to attach the motor lighters to, with wires internally through the fincan. Wiring all four of the airstarts takes a bit of time, and if you remember at LDRS, David Reese almost launched it before we got back from the pad.
CJ has great advice on the altimeters, but personally, I prefer the SLCF. It has a terminal block to hook up a switch to, and I like to download data after a flight. This might not be important to you now, and you can definitely own more than one altimeter.

 

[Mr G]

I’m looking forward to seeing what you come up with!

For me, this is working toward a far-in-the-future sci-fi rocket with motors in outboard pods (of course)! I’ve seen someone else try to light all those outboard motors on the pad, and it ended ugly. I think the best way to light outboards is after the rocket is on its way on a strong central motor, so I want to get some practice before I build a special rocket that would rely on airstarts.

Just bought a PET2+ timer to play with. After two failed attempts getting all three composite motors lit at lift off with two outboard boosters, I'll try putting the booster motors on the PET2+ circuit. Since the outboards will be fast burners, hopefully they will respond instantaneously at main ignition. This will be on the Ventris SRB that will now be aa flying test bed (see https://www.rocketryforum.com/threads/ventris-srb.137453/). Likely try the G25W for main and E18Ws in the boosters again with a BP pellet added in the G25. I'll also hook up the starters in series to assure continuity.

From there it will be tests with the PET2 with relatively small motors. If things don't work, the Ventris is cheap to replace. An upscale 68" x 4" diameter Ventris SRB is in the works that will take up to J motors. That one will need to work the first and every time.

 

[ThirstyBarbarian]

I used the PET-2 timer to start all four of the outboards on "Tweety Bird". I went over the settings on it with Jim Amos, he is a great guy to work with and pretty easy to get a hold of. I won't say the programming is easy, but with his help I managed to get all the motors lit on time. My PET-2 was mounted directly above one of the motor mount tubes with access through a little door. Jim advised me to use a standard 9v battery, so I replaced the LiPo in the picture. We also discovered that mounting it with the X axis pointing up is necessary for it to operate correctly. I think you can program it to operate in three different positions, but mine was mounted upside down in the picture.

I mounted terminal blocks on the bottom of the aft centering ring to attach the motor lighters to, with wires internally through the fincan. Wiring all four of the airstarts takes a bit of time, and if you remember at LDRS, David Reese almost launched it before we got back from the pad.
CJ has great advice on the altimeters, but personally, I prefer the SLCF. It has a terminal block to hook up a switch to, and I like to download data after a flight. This might not be important to you now, and you can definitely own more than one altimeter.

Thanks for the info on the PET-2. I took a quick glance at the instructions, and it looks like the programming is a bit tedious, but hopefully I’d be able to use it mostly in a default mode, at least in the beginning.

 

[blackjack2564]

What CJ was suggesting is to use a timer to light the airstarts, and to have it mounted in the fin can. That way you don’t need to route the wires to a forward altimeter. Then use a separate altimeter mounted in the forward av bay for deployment. I’m liking that idea.

Exactly and consider this... timer & altimeter are about the same money for both, as an entry level altimeter that can handle both functions [airstarts /dual deploy] Less hassle to doe the settings.

. But CJs suggestion that it might make more sense to use 2 separate devices makes me think this might be an easy way to modify my existing Warlock for the airstart timer. It’s probably easier than cutting a door into the existing fin can, right?

The built Warlock has a central 38mm. I could drill holes for 2 outboard motors on opposite sides of the central 38. And then drill a separate hole for the airstart module.

Yes keeping the unit close to motors is a plus, less wiring/conduits to fool with. Using extra motor tube is great, You make simple bay that fits right into it. Removable and prepping becomes a breeze.

Thanks for the info on the PET-2. I took a quick glance at the instructions, and it looks like the programming is a bit tedious, but hopefully I’d be able to use it mostly in a default mode, at least in the beginning.

All of the available unit seem tedious, just like the first time you built a reload.After a few times it's second nature.
Yes default mode is why I recommended it. No brainer. Just remember the unit has a "nose" up orientation AND IT MUST BE IN VERTICAL POSITION WHEN TURNED ON TO FUNCTION CORRECTLY.

To add delay you press the button over & over for each second added [basically] also partial seconds .25 .5 .75 etc. But ne need to even think about that till you have several good flights using "At Burnout" default.

You can use "at motor ignition" to start outboards as soon as central senses lift off to safely light all motors at pad. [so to speak]
Even with " at burn out' there is approximately .75 second delay just due to time chip sends signal and motor lights. Blink your eye...that fast. Great thinking on using Alt. for apogee, never need to worry about picking correct delay anymore.
You can use 2 matches for one apogee charge,... giving you n extra safety margin when just using 1 altimeter.

All this will enable you to re-fit your existing rocket quite economically!
Of course you will need to augment your motors for easy ignition [unless using CTI with pellets built in] but there are several ways to skin that cat.
Placement of switch or switch wire if using twist and tape can come out bottom of av-bay tube. Don't even need any conduit if you place terminal block on exterior of BP & wire igniters all to that!

 

[blackjack2564]

Question for CJ is where do you mount the timer and how do you wire the air starts? Do the wires break somewhere during deployment?

You can mount it different ways depending on how large your rocket is [space available]. It can be between fins with removable hatch. In an av-bay from above.[need wire break here] & conduit.
When from near/next to motors you can run ignition wires direct in some case or through shared conduit. You must first have an idea of how many/size of motors and space needed for electronics.
The are many ways to connect with plug ins or twisting wires.Even terminal blocks mounted on rear centering ring, if it is large enough.
I like using cut down JST connectors [same red ones for battery to Lipo]

One side hooked up to terminal on av-bay bulk plate & other soldered to my starter leads.

 

[Cameron Anderson]

Thanks for the info on the PET-2. I took a quick glance at the instructions, and it looks like the programming is a bit tedious, but hopefully I’d be able to use it mostly in a default mode, at least in the beginning.

Definitely play with it before your launch! I got mine and was a little confused at first, but after 20 minutes of toying with it, you come to appreciate the ingenuity of the design and you'll be far more comfortable using it. Get some LED lights and use them to test your output settings before you fly.

 

[JDcluster]

I'd buy the Pet 2 but don't like it's menu structure.
When arming the electronics; arm deployment charges first and the igniters last... Always!


JD

 

[ThirstyBarbarian]

Exactly and consider this... timer & altimeter are about the same money for both, as an entry level altimeter that can handle both functions [airstarts /dual deploy] Less hassle to doe the settings.



Yes keeping the unit close to motors is a plus, less wiring/conduits to fool with. Using extra motor tube is great, You make simple bay that fits right into it. Removable and prepping becomes a breeze.



All of the available unit seem tedious, just like the first time you built a reload.After a few times it's second nature.
Yes default mode is why I recommended it. No brainer. Just remember the unit has a "nose" up orientation AND IT MUST BE IN VERTICAL POSITION WHEN TURNED ON TO FUNCTION CORRECTLY.

To add delay you press the button over & over for each second added [basically] also partial seconds .25 .5 .75 etc. But ne need to even think about that till you have several good flights using "At Burnout" default.

You can use "at motor ignition" to start outboards as soon as central senses lift off to safely light all motors at pad. [so to speak]
Even with " at burn out' there is approximately .75 second delay just due to time chip sends signal and motor lights. Blink your eye...that fast. Great thinking on using Alt. for apogee, never need to worry about picking correct delay anymore.
You can use 2 matches for one apogee charge,... giving you n extra safety margin when just using 1 altimeter.

All this will enable you to re-fit your existing rocket quite economically!
Of course you will need to augment your motors for easy ignition [unless using CTI with pellets built in] but there are several ways to skin that cat.
Placement of switch or switch wire if using twist and tape can come out bottom of av-bay tube. Don't even need any conduit if you place terminal block on exterior of BP & wire igniters all to that!

This sounds like a pretty good setup to me.

For making the bay that fits into a motor tube, can the PET2 fit inside a 29mm tube? Or should I plan on a 38mm tube for the bay? I think I’m going to plan on 2x29mm for the actual motor tubes, but not sure what to order for the airstart bay.

It sounds like there are a few things to think through on how to set up the airstart module to go into the motor tube. If possible, I’d like to get as much of it off the shelf and easy to assemble.

 

[ThirstyBarbarian]

I'd buy the Pet 2 but don't like it's menu structure.
When arming the electronics; arm deployment charges first and the igniters last... Always!


JD

Thanks for the tip. Can I ask why you always arm deployment charges first? I have to say, with the switch prolly having to be on the aft end of the rocket, I am a little terrified of arming igniters while basicaly staring up the barrel. I think I’m finally going to need a written checklist for my launches. The details are going to overflow my noggin.

 

[ThirstyBarbarian]

Just bought a PET2+ timer to play with. After two failed attempts getting all three composite motors lit at lift off with two outboard boosters, I'll try putting the booster motors on the PET2+ circuit. Since the outboards will be fast burners, hopefully they will respond instantaneously at main ignition. This will be on the Ventris SRB that will now be aa flying test bed (see https://www.rocketryforum.com/threads/ventris-srb.137453/). Likely try the G25W for main and E18Ws in the boosters again with a BP pellet added in the G25. I'll also hook up the starters in series to assure continuity.

From there it will be tests with the PET2 with relatively small motors. If things don't work, the Ventris is cheap to replace. An upscale 68" x 4" diameter Ventris SRB is in the works that will take up to J motors. That one will need to work the first and every time.

The PET2+ sounds like a good plan for getting the outboards lit. Is the G25 enough to fly the rocket safely on its own? My thought is that the central motor needs to be enough to fly the rocket, even if the outboards fail. I’m not sure you can count on the outboards lighting while the rocket is still on the rail.

 

[Mr G]

The Ventris is really light, even with boosters. Smallest recommended motor is an F26 so no concern with a G25.

 

[boatgeek]

Jumping in to the thread with both feet...

Thanks for the list of altimeters — looks like lots of options!

For your Eggtimer Quantum, have you used the WiFi interface? Is that something you can access with an iPhone? For any of the Eggtimer products, I’d need someone to build the kit for me.

I’ll take a look at the other models you mentioned as well. Thanks!

I've only operated the Quantum off of my iPhone. It's an easy setup and the menus are intuitive. With a couple of LED test lights and the on-board testing routine, you can get the feel for the settings before you fly.

Thanks again for all the info.

I’ve taken a look at the 2 altimeters you mentioned, and it looks like the RRC2+ would be about the simplest to use.

...

For now, the main reason I feel like I need the electronic deployment is in case the outboard airstarts don’t light. I want the ejection to occur at apogee either way. I’m not planning on very high flights at this point, so it’s mostly about ensuring against crashes if the airstarts fail.

I've used both the RRC2+ and the Stratologger CF. The RRC is definitely easier to use though I do like the set of switch terminals that the CF has. My only complaint about the CF is that it doesn't have a basic preset for a 1s after apogee drogue charge, so if you are using two CFs as redundant altimeters, you'll want to get into programming with the computer. On the other hand, the RRC is a really nice backup to the CF.

Thanks for the tip. Can I ask why you always arm deployment charges first? I have to say, with the switch prolly having to be on the aft end of the rocket, I am a little terrified of arming igniters while basicaly staring up the barrel. I think I’m finally going to need a written checklist for my launches. The details are going to overflow my noggin.

If something goes horribly wrong and the outboards light during timer startup, having deployment altimeters already armed means that your rocket comes down under parachute. If you arm deployment altimeters after igniters are in the rocket, you risk the rocket coming in ballistic if something trips the igniter.

 

[blackjack2564]

This sounds like a pretty good setup to me.

For making the bay that fits into a motor tube, can the PET2 fit inside a 29mm tube? Or should I plan on a 38mm tube for the bay? I think I’m going to plan on 2x29mm for the actual motor tubes, but not sure what to order for the airstart bay.

It sounds like there are a few things to think through on how to set up the airstart module to go into the motor tube. If possible, I’d like to get as much of it off the shelf and easy to assemble.

It will easily fit into 29 tube....but you will use coupler to fit inside bay. A bit tight but doable.
Being first time, I would go up to 38 if at all possible. Gives more options for how to install gear & batteries.

Think about how you will switch on power before building... as your switch [if using one] can be wired in from top,side or under and mounted on airframe, so you ain't looking directly up the pooper when arming!

Don't worry about where to put it. Just make your choice of locations & ask how. Everything will be off shelf,ya may have to drill it, beat on it, or glue it.lol

And....another thing. Whole process gets much easier of you design your rocket around motor combo intended to fly.

 

[BayouRat]

Who's building Eggtimer's these days? I paid someone $35 to do my first two. Can't remember who it was. I hate getting old.