Two stagers using MPR (Composite Ds, Es, and Fs)

[gdjsky01]

Anyone build such a rocket? What did you use for a timer? How did you run the wiring? What did you use for coupling? 'Starters'? Battery? Timer bay? Altimeter? Dual Deploy as well? Sizes?

Designs? Pictures? Techniques?
No?

 

[bradycros]

What happend to the Rose-A-Roc build thread?

 

[gdjsky01]

No worries... Just haven't updated it yet. I am going slow. Only two more steps.

In the mean time I'd like ideas on smaller composite two stagers. Especially (obviously) the staging part! :wink:

 

[AKVP]

Hey Jeff-

Wow, I will be watching this thread. I hope it gets many replies. I was wanting to try this at some point too! very cool.

The staging part: Does the Aux output on the new RRC3 have a "timing" option? For example: In the second stage, the RRC3 would cover (its own dual) recovery AND the ignition of its motor via the aux output. The booster can deploy on motor delay. That way, you can do this with ONE altimeter, and if the second stage fails to ignite, the same altimeter would still take care of recovery. If this is the case, maybe that could be an option?

HMMMM.....

 

[Handeman]

You definitively want DD on the sustainer. Probably the most common 2 stage failure is the second stage not lighting. DD will get your rocket back in one piece.

 

[JPVegh]

https://www.apogeerockets.com/Electronics_Payloads/Staging/PerfectFlite_MiniTimer4_Staging_Timer

 

[Wayco]

The Raven was designed with this in mind, it has four outputs that can light the sustainer, separate the stages and operate DD all in one. The RRC3 might have an aux. output board for this, but I don't think it is out yet.
Jim Jarvis is flying two stage composites, maybe he will post up.

 

[gdjsky01]

The trick is mounting it all. Running the wires.. etc...
J

 

[daveyfire]

Anyone build such a rocket? What did you use for a timer? How did you run the wiring? What did you use for coupling? 'Starters'? Battery? Timer bay? Altimeter? Dual Deploy as well? Sizes?

My TARC rocket was a MPR two stager. Man, this was a while ago--

• Timer -- Kinda, GWiz LC in the upper stage using the "stage" option.
• Wiring -- avionics were in a payload section at the top of the sustainer (in the "traditional" place, below the nose cone). Wires for deployment and staging ran through the coupler/bulkplate assembly at the base of the payload. (I only mixed them up once.) A deployment charge was placed at the bulkplate for apogee deploy. The staging wires were loosely twisted to igniter wires running up from the aft end of the sustainer through a small tube placed in the centering rings. At deployment, the twisted wire ends pulled apart.
• Coupling -- Used a FlisKits coupler with a G10 bulkhead glued in the middle of it. Motor deploy on the bottom stage -- the coupler/bulkplate assembly was the "interstage". I think I fiberglassed the inside of the coupler to make it easier to clean after staging.
• 'Starter' -- Oxral and/or davey and/or BSR matches -- the HiRMI minis would fit in most 29mm F motors, even.
• Battery -- 9V with the GWiz -- heavy but reliable. A LiPo would probably work these days, but be careful you don't blow the output FET on your timer/altimeter/airstart thingy when the sustainer igniter wires inevitably short after ignition. A resistor in series with the match would keep that from happening if you have a flight computer with low rated outputs. (The Perfectflite MT4 can dump 45A. No problems there.)
• Timer bay -- none! The all in one unit made this easy.
• Altimeter -- see previous
• Dual Deploy -- nah, just ran single deploy, but it saved our butt a few times when the sustainer didn't light.

• Sizes -- 29mm booster/sustainer, BT70 tubes. Fliskits components with LOC MMT.

• Fun factor -- like a million plus one. The first time it staged, I about died from happiness.

 

[JimJarvis50]

My TARC rocket was a MPR two stager. Man, this was a while ago--

• Timer -- Kinda, GWiz LC in the upper stage using the "stage" option.
• Wiring -- avionics were in a payload section at the top of the sustainer (in the "traditional" place, below the nose cone). Wires for deployment and staging ran through the coupler/bulkplate assembly at the base of the payload. (I only mixed them up once.) A deployment charge was placed at the bulkplate for apogee deploy. The staging wires were loosely twisted to igniter wires running up from the aft end of the sustainer through a small tube placed in the centering rings. At deployment, the twisted wire ends pulled apart.
• Coupling -- Used a FlisKits coupler with a G10 bulkhead glued in the middle of it. Motor deploy on the bottom stage -- the coupler/bulkplate assembly was the "interstage". I think I fiberglassed the inside of the coupler to make it easier to clean after staging.
• 'Starter' -- Oxral and/or davey and/or BSR matches -- the HiRMI minis would fit in most 29mm F motors, even.
• Battery -- 9V with the GWiz -- heavy but reliable. A LiPo would probably work these days, but be careful you don't blow the output FET on your timer/altimeter/airstart thingy when the sustainer igniter wires inevitably short after ignition. A resistor in series with the match would keep that from happening if you have a flight computer with low rated outputs. (The Perfectflite MT4 can dump 45A. No problems there.)
• Timer bay -- none! The all in one unit made this easy.
• Altimeter -- see previous
• Dual Deploy -- nah, just ran single deploy, but it saved our butt a few times when the sustainer didn't light.

• Sizes -- 29mm booster/sustainer, BT70 tubes. Fliskits components with LOC MMT.

• Fun factor -- like a million plus one. The first time it staged, I about died from happiness.

Ah, yes, the fun factor! I would have to agree. When I got my first two-stager, though, I just sat on the floor with the parts and tried to figure out where everything would go. Seemed like rings within rings within rings.

You can indeed do pretty much everything you need to do for two stagers with a Raven. They are a bit tricky though. If you use one, I would recommend that you run your plan by Adrian for a double check. I still do, and he catches a lot of errors. One advantage of the Raven is that you can program some safety measures that basically don't allow the sustainer to light unless the flight is nominal. I think this is important even for smaller two-stagers. As time goes on, fewer launches will allow two-stage flights with timers only. AirFest for example is requiring some form of sustainer inhibit for anything with a K or larger in it, and I suspect this will generally be the case for >50K flights where Tripoli or FAA approval is required.

I haven't done any staging with small composite motors, so one question i would have is the availability of low-current igniters for those motors. If they are not available, then it might take a higher-current igniter, a lipo battery and FETs capable of handling the higher current.

I, too, use a breakwire through the drogue bay. I think it's a simpler option than electronics in more than one location, or worse, in the booster.

Jim

 

[blackjack2564]

Hey Jeff-



The staging part: Does the Aux output on the new RRC3 have a "timing" option? For example: In the second stage, the RRC3 would cover (its own dual) recovery AND the ignition of its motor via the aux output. The booster can deploy on motor delay. That way, you can do this with ONE altimeter, and if the second stage fails to ignite, the same altimeter would still take care of recovery. If this is the case, maybe that could be an option?

HMMMM.....

Yes it has a timer on Aux/pryo 3 output & can function as you describe.

The RRC3 might have an aux. output board for this, but I don't think it is out yet.

Wayco it's [staging/cluster] already built in the Aux function. There will be another igniter board available that will plug into the RRC3 with multiple terminals on it. Now you have 4-5-6 pyros for sequencing clusters. For instance 5 motors.
Main ignites on the pad, 2 more fire at 3 seconds with the aux, then the last 2 fire at 7 seconds with the plug in igniter board. You will be able to piggy back multiple boards & so on.

Along with firing a stage or cluster you can program it to fire only if rocket reaches a certain altitude, or greater than> or less than< a specified velocity.

I have done 6- 2 stage flights with mine. Currently it is set for: stage at 2.5seconds into flight, but only if rocket is at 1200ft altitude. Then dual deploy the sustainer. This is for the 2.1inch airframe [Vindicator Jr] with 38mm motor mounts 2 stage. For this flight it's a 3 grain white thunder[I- motor] to a 1 grain white thunder [G-motor] Demo flight expecting 4500-5000 ft.

 

[daveyfire]

You can indeed do pretty much everything you need to do for two stagers with a Raven. They are a bit tricky though. If you use one, I would recommend that you run your plan by Adrian for a double check. I still do, and he catches a lot of errors. One advantage of the Raven is that you can program some safety measures that basically don't allow the sustainer to light unless the flight is nominal. I think this is important even for smaller two-stagers. As time goes on, fewer launches will allow two-stage flights with timers only. AirFest for example is requiring some form of sustainer inhibit for anything with a K or larger in it, and I suspect this will generally be the case for >50K flights where Tripoli or FAA approval is required.

I haven't done any staging with small composite motors, so one question i would have is the availability of low-current igniters for those motors. If they are not available, then it might take a higher-current igniter, a lipo battery and FETs capable of handling the higher current.

I definitely agree -- the Raven is now the obvious choice for intelligent flight control, even in an MPR-size rocket -- perhaps especially in an MPR-size rocket, since the things are so tiny and can use a single-cell Lipo. Has anybody tried dipping Q2G2s for sustainer ignition? Those might be the ticket nowadays.

 

[Wayco]

My whole evolution in rocketry began with an Estes Mongoose. When the C6-5 lit and the booster popped off, I was hooked. Went out and got a Dyna-Star Rip-Roar. Wore it out and built another one. I was putting together a plan to upscale the Rip-Roar and shared it with my good friend Guy Smith. He went into his secret laboratory (garage) and brought out pretty much what I had in mind, already built. We talked about how he would use the Raven to do all this stuff and I knew I would probably never be able to figure it out.
So when Jim Jarvis posted up in this thread, that verified my original decision not to try it.
Now CJ tells me I have an altimeter that he uses to fly two stage all the time! Gotta love this forum, now the 2x upscale Rip-Roar is back in my plans.
Thanks to Jeff for starting this thread and to all of you that contributed. My dream rocket has been reborn! Might be a while before I start a build thread, gotta order some parts first.

 

[JimJarvis50]

My whole evolution in rocketry began with an Estes Mongoose. When the C6-5 lit and the booster popped off, I was hooked. Went out and got a Dyna-Star Rip-Roar. Wore it out and built another one. I was putting together a plan to upscale the Rip-Roar and shared it with my good friend Guy Smith. He went into his secret laboratory (garage) and brought out pretty much what I had in mind, already built. We talked about how he would use the Raven to do all this stuff and I knew I would probably never be able to figure it out.
So when Jim Jarvis posted up in this thread, that verified my original decision not to try it.
Now CJ tells me I have an altimeter that he uses to fly two stage all the time! Gotta love this forum, now the 2x upscale Rip-Roar is back in my plans.
Thanks to Jeff for starting this thread and to all of you that contributed. My dream rocket has been reborn! Might be a while before I start a build thread, gotta order some parts first.

Well, one thing I've found is that figuring out how to use these altimeters to provide a safety feature that actually works is a bit of an art. First, you need a good simulation, which isn't all that easy for two-stagers. Then, you have to understand how the signals that the altimeter will use are actually generated. An example here is whether or not the altitude signal is filtered, and thus, delayed. Another issue is to determine how the flight profile will affect the sensors. An example here might be how the RRC3 would respond if the flight is above Mach 1 and the altimeter altitude reading gets spoofed. Last but not least is understanding how inaccuracies in the sensors will affect the flight plan and how to compensate. The consequences of screwing this stuff up are that you might waste a booster motor if the sustainer doesn't light, or you might get deployment or staging when you didn't really want it. Both have happened to me, but this is exactly the type of thing that makes two-stagers fun.

Jim

 

[Wayco]

Thanks for the additional data Jim. Your "FourCarbYen" and "TwoCarbYen" flights at black rock last month were both awesome. Put you in the "Rocket Gods" category in my book. Hard to imagine what altitude you would have achieved if the N-1100 would have lit. The conversation you had with Adrian in your flight report pretty much proves how complex these flight are, no way can I understand all the data you collected from those two flights. Congratulations on the record setting TCY flight, quite a feat at Black Rock.
Any chance you will be attending Airfest this month? Would love to see one of your rockets in flight!

 

[JimJarvis50]

Any chance you will be attending Airfest this month? Would love to see one of your rockets in flight!

I previously twice tried the same TCY flight at AirFest. The first time I tried it, the rocket shreaded at sustainer burnout. Never did figure out why, and it was just dumb luck that I found all the parts.

By the second attempt, I was starting to get an inkling that it might bust the waiver there. So, to hedge my bets, I programmed the Raven to deploy the apogee charge in the event that the rocket was at 46K and still going up. The Raven did exactly that, but the rocket was still going above Mach 1 at the time. A serious zipper and shreaded chute resulted from that, and I knew I had a problem when we saw from a distance that all of the parts were within about a five-foot circle (that ain't right!). So, I had to take it to Black Rock, but at least I finally got it right. While I can't fly my larger two-stagers at Argonia, I have some others I might bring.

Jim

 

[gdjsky01]

More more more. Keep those ideas and caveats coming. We all have seen the the J's and I's. but what about the F's and G's? I'd contribute more but I type this literally from a tropical Island. Work is a bit*h. :y:

 

[wetmelon]

Sorry to interrupt, I'm just curious about your terminology. Are you guys calling the second stage motor in a sequentially staged rocket the "sustainer"?

 

[Wayco]

Sorry to interrupt, I'm just curious about your terminology. Are you guys calling the second stage motor in a sequentially staged rocket the "sustainer"?

That is correct.

 

[apburner]

OK what I need to know is how the upper and lower stage couple. I understand the electronics and it should be simple enough. But I have not seen any really good closeups of the interstage coupler with explanations.

 

[daveyfire]

Here's my attempt. This is using a CAD model of a Wildman Two Stage, but is applicable at most MPR/HPR two stage scales.

The sustainer has shortened fin roots, and the aftmost centering ring is placed up against the base of them. This will allow clearance for the interstage coupler. Conduit is run through the centering rings from the front end of the motor tube to provide a wire pathway to ignite the sustainer. Terminate the conduit ~0.5-1" below the motor mount end to make it easy to find it during prep while still allowing clearance for a motor retainer (e.g., Aeropack).

The interstage coupler is simply a coupler with an internal bulkplate or two.

Thrust is transferred via the joint between the forward end of the booster tube and the aft end of the sustainer tube. You can add a "switchband" to it if you'd like (as shown). This provides three benefits:

(1) allows the coupler to help in transferring thrust loads (via the switchband and also now against the aft centering ring of the sustainer);
(2) providing a place for arming switches for booster avionics;
(3) providing a location for vent holes if you want to do "fire in the hole" staging, when the sustainer is separated from the booster by the sustainer motor's exhaust (vs. by drag or by a separation charge).

Speaking of separation charges, one can be placed in the plenum created by the interstage coupler, and wired in parallel with the sustainer igniter. Unless you are using an "instant on" igniter, the charge will fire and clear the stages prior to second stage motor pressure up. Here is a cutaway view showing the space for sustainer igniter/separation charge:


With this assembly complete, the sustainer becomes the booster's "nose cone".

Electronics for the booster can be placed in the interstage coupler. These electronics can also control staging if you're going the "fire in the hole" route, but the problem is that if the booster drag separates unintentionally, you will not achieve second stage ignition. Plus, drag separation followed by staging looks so much cooler

It's a basic design that provides lots of flexibility. Other, more experienced two stagers (like Fred Taverni or Jim Jarvis, above) probably have better designs. This one is easy and inexpensive, both which I like.

 

[JimJarvis50]

Here's my attempt. This is using a CAD model of a Wildman Two Stage, but is applicable at most MPR/HPR two stage scales.

The sustainer has shortened fin roots, and the aftmost centering ring is placed up against the base of them. This will allow clearance for the interstage coupler. Conduit is run through the centering rings from the front end of the motor tube to provide a wire pathway to ignite the sustainer. Terminate the conduit ~0.5-1" below the motor mount end to make it easy to find it during prep while still allowing clearance for a motor retainer (e.g., Aeropack).
View attachment 142062
The interstage coupler is simply a coupler with an internal bulkplate or two.
View attachment 142066View attachment 142063
Thrust is transferred via the joint between the forward end of the booster tube and the aft end of the sustainer tube. You can add a "switchband" to it if you'd like (as shown). This provides three benefits:

(1) allows the coupler to help in transferring thrust loads (via the switchband and also now against the aft centering ring of the sustainer);
(2) providing a place for arming switches for booster avionics;
(3) providing a location for vent holes if you want to do "fire in the hole" staging, when the sustainer is separated from the booster by the sustainer motor's exhaust (vs. by drag or by a separation charge).

Speaking of separation charges, one can be placed in the plenum created by the interstage coupler, and wired in parallel with the sustainer igniter. Unless you are using an "instant on" igniter, the charge will fire and clear the stages prior to second stage motor pressure up. Here is a cutaway view showing the space for sustainer igniter/separation charge:
View attachment 142064

With this assembly complete, the sustainer becomes the booster's "nose cone".
View attachment 142065
Electronics for the booster can be placed in the interstage coupler. These electronics can also control staging if you're going the "fire in the hole" route, but the problem is that if the booster drag separates unintentionally, you will not achieve second stage ignition. Plus, drag separation followed by staging looks so much cooler

It's a basic design that provides lots of flexibility. Other, more experienced two stagers (like Fred Taverni or Jim Jarvis, above) probably have better designs. This one is easy and inexpensive, both which I like.

Excellent description! I have a rocket where the interstage coupler is just like that. I don't use switches on the switch band, but having one keeps the coupler in position and lets the coupler serve as the booster nose cone after the sustainer leaves. The position of the bulkhead can be moved around to provide just enough room for the separation charge, and I like to line the inside of the coupler with fiberglass or carbon since the coupler is where many staging failures occur. Obviously, the design changes for minimum diameter.

That little surface-mounted area at the bottom of the fins is worth paying some attention to. My first two-stager had that, along with inadequate fin thickness, and the general rocket design and the flight were very similar to the well known USS Bakula flight ( https://www.youtube.com/watch?v=J0dx9eYU5rs and https://www.videorocketry.com/XPRS_2004/ ) except that my fins came off. It was very evident that the surface mounted fin tab is what fluttered first, as a pie-shaped area of paint was scraped off the body tube at the bottom of each fin. I wish I had a picture of that because it was quite interesting. So, you just want to make sure that area of the fin is securely attached.

Jim