Two stage help

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T34zac

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So I started in the developmental process of building a two stage high power rocket, and I have a couple of questions:

1) Which section do I put the staging timer? In the booster, or the sustainer?

2) If the timer belongs in the booster, do I have to worry about drag separation before ignition of the sustainer?

3) If so, how should I deal with this problem? With shear pins, or making the coupler tighter than normal?

4) If the timer belongs in the sustainer, how do I deal with the long igniter trailing from the back end of the rocket after ignition?

Any and all help is appreciated, thank you!
 
There are a number of two-stage build threads on this forum, have you looked at those? Most touch on all the questions you bring up.
 
So I started in the developmental process of building a two stage high power rocket, and I have a couple of questions:

1) Which section do I put the staging timer? In the booster, or the sustainer?

Whichever you choose.
2) If the timer belongs in the booster, do I have to worry about drag separation before ignition of the sustainer?

Yes.
3) If so, how should I deal with this problem? With shear pins, or making the coupler tighter than normal?

I prefer shear pins, but again, your choice.
4) If the timer belongs in the sustainer, how do I deal with the long igniter trailing from the back end of the rocket after ignition?

It won't hurt, but you can use separate lead and ignitor wires twisted together. Chances are the ignitor will be blown away with only a small amount of lead wire extending out the aft end.
Any and all help is appreciated, thank you!
 
Please try and search the forum before you ask questions like these. However, I will answer a few for you (you are new and all, so why not).
So I started in the developmental process of building a two stage high power rocket, and I have a couple of questions:

1) Which section do I put the staging timer? In the booster, or the sustainer?
Sustainer. This will prevent the problem in question 2. Because of this, questions 2 and 3 are moot.


4) If the timer belongs in the sustainer, how do I deal with the long igniter trailing from the back end of the rocket after ignition?
It will simply burn up in the exhaust or come off or something. Don't worry about it.

Any and all help is appreciated, thank you!


I am in the process of building a 2 stager myself. I know how frustrating some of the things can be. Just wondering, do you have any pictures of the rocket? Also, what timer are you using?

Welcome aboard!!
 
Whichever you choose.


Yes.


I prefer shear pins, but again, your choice.


It won't hurt, but you can use separate lead and ignitor wires twisted together. Chances are the ignitor will be blown away with only a small amount of lead wire extending out the aft end.

Thank you for your help. This is exactly the answers I was looking for. Once I start building I will make a build thread for it.
 
Please try and search the forum before you ask questions like these. However, I will answer a few for you (you are new and all, so why not).



I am in the process of building a 2 stager myself. I know how frustrating some of the things can be. Just wondering, do you have any pictures of the rocket? Also, what timer are you using?

Welcome aboard!!

Like I said, it's still in the developmental process (rocksim). This came as a challenge from my father on Sunday after receiving my L1 cert. I told him it would be ready for the next time LDRS is in NY, on Tuesday I found out my deadline is shorter than expected.
 
4) If the timer belongs in the sustainer, how do I deal with the long igniter trailing from the back end of the rocket after ignition?
I prefer staging electronics in the stage that is being lit. I built small bays at the aft end of both upper stages of my Comanche 3 and ran a small tube down to the aft centering ring.
 
I prefer staging electronics in the stage that is being lit. I built small bays at the aft end of both upper stages of my Comanche 3 and ran a small tube down to the aft centering ring.

Ok. I might do something like that to keep everything looking clean. Now time to edit the rocksim file to reflect that.
 
I have one more question for anyone still looking at this thread:

Should I use fiberglass? And if so where should I buy the fiberglass?

I was originally planning on using PML phenolic, but after browsing some threads here I noticed a lot of people like to use fiberglass. The rocket I used for my level 1 cert was Madcow fiberglass. My level 2 cert will also be Madcow fiberglass. But this project is already looking more expensive than I originally thought, so I decided on phenolic to cut cost a bit.

Edit: I forgot to mention that the centering rings, bulkheads, and fins are all going to be PML G-10 fiberglass.
 
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Well if it helps, Wildman has the 2-stage Wildman jr [ 54mm [2.1 in. dian.] airframe, 38mm motor mount] on sale for July 200.00

All fiberglass,interstage coupler-booster-sustainer. You add hardware,electronics, recovery .

Add up individual parts pretty much anywhere and it's WAY higher than buying a kit.

Linky:

https://www.wildmanrocketry.com/ShowProducts.aspx?Class=463&Sub=840


You can also do L-2 with the sustainer.
 
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Unreinforced phenolic will be just fine. Fiberglass is more durable, but heavier. It's also easier to finish because it has no spiral grooves.
 
Unreinforced phenolic will be just fine. Fiberglass is more durable, but heavier. It's also easier to finish because it has no spiral grooves.

Thank you for a straight answer. But I may just go with fiberglass after seeing the prices on wildman's site (I had never been on that site before). Very reasonable for everything
 
Thank you for a straight answer. But I may just go with fiberglass after seeing the prices on wildman's site (I had never been on that site before). Very reasonable for everything


Welcome to the dark (star) side.... :dark: Heavier components, bigger motors.... Use the force Luke.
Saving money is not an option. Join the Wildman club, it helps. Especially for the Black Saturday sales in November.
 
Welcome to the dark (star) side.... :dark: Heavier components, bigger motors.... Use the force Luke.
Saving money is not an option. Join the Wildman club, it helps. Especially for the Black Saturday sales in November.

I figured joining the wildman club was going to help. I did all (and by all I mean most, but most was good enough to convince me) of the math for the savings from joining. Just the motor casings would almost make up for the membership fee.
 
It took my awhile to this, it should help you no matter who's kit you decide to go with.

It is by no means the only way to build a 2-stager , but it is the instructions for Wildman kits and should at least give you a good starting point.

https://www.rocketryforum.com/showt...e-build-Vindicator-JR&highlight=wildman+stage


Good luck with your adventure into staging!!


By the way... if you use CTI for your L-2.... buy the reload of your choice & get the motor case free.
 
Hi T34zac,

I too am at the very early research/design phase of a 2 stage Black Brant X, likely 2015 or 2016, and while combing through the endless postings on TRF as well as reviewing manufactures timers and staging technologies I came across this timely thread.

Not to hijack your thread or duplicate answered questions however I cannot seem to find clarification on one point…possibly this is because it's obvious to everyone.

What is the means of separating the stages? Is it achieved with an event, such as a BP charge or other pressurization method, is it through drag sep, although I have read many threads including this one mentioning the usage of sheer pins to prevent this, or is it achieved simply by the ignition of the second stage. If it is the second stage ignition which pressurizes the stages to achieve sep then what is to stop the heat of the exhaust from damaging the previous stage?
 
Hi T34zac,

I too am at the very early research/design phase of a 2 stage Black Brant X, likely 2015 or 2016, and while combing through the endless postings on TRF as well as reviewing manufactures timers and staging technologies I came across this timely thread.

Not to hijack your thread or duplicate answered questions however I cannot seem to find clarification on one point…possibly this is because it's obvious to everyone.

What is the means of separating the stages? Is it achieved with an event, such as a BP charge or other pressurization method, is it through drag sep, although I have read many threads including this one mentioning the usage of sheer pins to prevent this, or is it achieved simply by the ignition of the second stage. If it is the second stage ignition which pressurizes the stages to achieve sep then what is to stop the heat of the exhaust from damaging the previous stage?

I had a similar question. My solution was going to be coating the inside of the interstate with the heat resistant paint used to coat the inside of grills (good for 2000 F as it says on the label) and separate via sustainer ignition. Anyway, good luck on your project, I was always a fan of the Black Brant design.
 
Ok now I have a question about what electronics to get. I'm planning on using an altimeter in the booster for dual deployment (with motor backup at apogee), a timer in the sustainer for separation and second stage ignition, an altimeter in the sustainer for dual deployment, and a GPS in the nose cone (I'm expecting 22k out of it). So I ask which of each type of electronics to get? Also it would be preferable if timer has more than two outputs because I'm thinking of using the third as an apogee ejection backup since the motor is plugged.

And yes I have been searching the forum but I have not come to decisive conclusion on which ones to use as everyone has a specific reason to like one over another and then someone else always has a counterpoint to like the one the other person disliked.
 
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I had a similar question. My solution was going to be coating the inside of the interstate with the heat resistant paint used to coat the inside of grills (good for 2000 F as it says on the label) and separate via sustainer ignition. Anyway, good luck on your project, I was always a fan of the Black Brant design.

I would be careful using the rattle cans for high heat situations, unless they are cured. To clarify, most of those paints are meant for high temperature but require it to be cured; whether it be from application or oven. For example the engine enamel cures from the heat of running the engine and the BBQ paint from the heat of having a BBQ. If used on an application such as a rocket the short burst of heat will not suffice as a "cure," and will not have the stated temperature rating. If I remember correctly VHT Paint (Dupli-Color) said if their paint was not cured it could withstand about ~170F and the Rust-Oleum brand was about that also I think.
 
I would be careful using the rattle cans for high heat situations, unless they are cured. To clarify, most of those paints are meant for high temperature but require it to be cured; whether it be from application or oven. For example the engine enamel cures from the heat of running the engine and the BBQ paint from the heat of having a BBQ. If used on an application such as a rocket the short burst of heat will not suffice as a "cure," and will not have the stated temperature rating. If I remember correctly VHT Paint (Dupli-Color) said if their paint was not cured it could withstand about ~170F and the Rust-Oleum brand was about that also I think.

Well I have a hotbox I can use
 
Here are a few thoughts on your questions ....

Regarding where to put the staging electronics, I put them in the sustainer. The main reason for this is that I prefer to separate the stages before the sustainer motor lights. Separating the stages allows you more control over the flight profile and prevents damage to the interstage coupler. If you're really planning to fly to 22K, then you'll want to be able to control the flight profile. I had a flight last weekend where I'm pretty sure my separation charge didn't actually separate the charges. There was a fair amount of damage to the coupler and the slimline retainer, and there were other issues that suggested this is what happened. I use a 0.3 gram separation charge in a 3" rocket, and perhaps I need to increase that a bit.

As it turns out, I also had a dangling ignitor wire on this flight. Doesn't ususally happen though. Just costs a little altitude if it happens.

If you put the staging electronics in the sustainer, there are a number of locations you could use. One location is between the motor mount and the airframe between the fins. There often isn't enough room for this though. Another option is to use the zipperless coupler approach and to put the electronics within the zipperless coupler. The option I use it to put the electronics in the conventional ebay position and then run breakwires through the drogue bay. I've never had this approach fail, although it is important to make sure both ends are tied off securly (or you might damage an altimeter).

As far as what electronics you use, please allow me space on the soap box for a moment. Two-stage flights are inherently more dangerous (roughly an order of magnitude IMO) than single stage flights for a variety of reasons. Your design should focus on safety as much as anything else. Your ignitor circuit should include a shunt that shorts out the ignitor. This is the last thing you open before leaving the pad, and I do it when no one else in around the rocket. You need to study up a bit on how to make shunts work properly (I use a small resistor in the ignitor circuit).

The other important thing is to use an altitude check before lighting the sustainer motor. You want to implement the logic "don't light the sustainer motor unless the rocket reaches at least xxx feet in less than yyy seconds". There are at least four altimeters that I'm aware of that can do this. The approach requires that you do a simulation of the conditions where you want the sustainer ignitor to fire, and then choose a sensible trigger altitude and/or time so that the flight has to be nominal or the sustainer won't light. I've seen many flights where the staging coupler breaks and then the sustainer motor lights (on a timer). They hit the ground under power or fly across the crowd horizontally. Lots of fun, but a bit of a hazard. Inhibited ignition is required at some fields, and it is easy to do. It is something you should do on your very first flight.

With respect to tracking, your basic options are RDF and GPS. GPS is getting more reliable, but it has not yet reached the reliability of RDF. I fly both, but if I had to choose one, it would be RDF.

I'm not a big fan of fiberglass two-stagers because of the weight. The two-stager I mentioned above is PML phenolic with a couple wraps of fiberglass. The rocket has a couple dozen flights on it, and the tubes are still in good shape. Another way to save weight is to go single deploy in the booster, with electronics in the staging coupler. It is a good thing for two stagers to minimize the number of tube breaks.

Jim
 
I put them in the sustainer. The main reason for this is that I prefer to separate the stages before the sustainer motor lights.

That was what I was planning on doing.

If you put the staging electronics in the sustainer, there are a number of locations you could use. One location is between the motor mount and the airframe between the fins. There often isn't enough room for this though.

Yeah I was going to put the timer there.

Another option is to use the zipperless coupler approach and to put the electronics within the zipperless coupler.

I don't know what a zipperless coupler is..

The option I use it to put the electronics in the conventional ebay position and then run breakwires through the drogue bay.

That was something else I could do if it doesn't fit in in between the fins.

Your ignitor circuit should include a shunt that shorts out the ignitor. This is the last thing you open before leaving the pad, and I do it when no one else in around the rocket. You need to study up a bit on how to make shunts work properly (I use a small resistor in the ignitor circuit).

May I see how you do it just so I have all this info in (mostly) one place?

The other important thing is to use an altitude check before lighting the sustainer motor. You want to implement the logic "don't light the sustainer motor unless the rocket reaches at least xxx feet in less than yyy seconds". There are at least four altimeters that I'm aware of that can do this.

Which ones do this?

The approach requires that you do a simulation of the conditions where you want the sustainer ignitor to fire, and then choose a sensible trigger altitude and/or time so that the flight has to be nominal or the sustainer won't light.

How would I use rocksim to simulate separation? I know there is the ignition delay that I can use for the sustainer, but that doesn't seem to work the way I thought it did. That being said, I was planning on separation 0.1s after MECO and then ignite the sustainer 3s later.

Inhibited ignition is required at some fields, and it is easy to do. It is something you should do on your very first flight.

Yeah I figured it wasn't to difficult, I have worked with accelerometers before.

With respect to tracking, your basic options are RDF and GPS. GPS is getting more reliable, but it has not yet reached the reliability of RDF. I fly both, but if I had to choose one, it would be RDF.

What type of equipment will I need for RDF? Is it expensive? And would GPS be cheaper? If so I might sacrifice some reliability, as long as it can get me in the general area (I might put one of these on board: https://www.apogeerockets.com/Electronics_Payloads/Rocket_Locators/Transolve_BeepX , or make something similar)

I'm not a big fan of fiberglass two-stagers because of the weight.

----------

Another way to save weight is to go single deploy in the booster, with electronics in the staging coupler. It is a good thing for two stagers to minimize the number of tube breaks.

I'd rather use fiberglass. I'm a little more familiar with it. Also if I go too light I might break the waiver. I'm going to use 22k as a goal and if simulations go too far below that when I have almost everything configured correctly, then I may consider dropping some weight.

As for dual deploy, the booster after staging sims to 4.5k. That's already higher than anything I've ever launched (that will change by the time I build this). It was going to be dual deploy from a single bay with the electronics in the coupler, using the cable cutter method.

Thank you for your very comprehensive response.
 
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