Thinking outloud here and thinking towards a worst case scenario, of the three main motors, only two ignite in the booster, and only three of the 6 outboards ignite, and they are all on basically one side so that a tilt is induced, the sustainer ignition is locked out by the tiltometer and now we have to get the whole thing down safely and preferably, undamaged. Do the explosive bolts then fire to separate stages? This would seem to have to happen so that the sustainer recovery sytem is not carrying the booster with it. You need the bolts to fire, separate stages, and then deploy the booster recovery sytem while the sustainer is doing it's thing. Is this correct and is this part of the plan? 😯

The separation staging event would be tied to detection of booster motor burnout. We can make the upper stage look for separation as a condition for ignition without making the staging wait for good ignition conditions. We should design the sustainer recovery to be able to handle the weight of having an unburned upper stage motor. I would assign the 6 outboards to the altimeter channels so that if one altimeter has a problem, it would affect 3 equally-distributed motors.

I think joining the sections with release bolts instead of a coupler could help the separation work if there is a lot of bending of the body. On the flip side, those bolts will need to be strong enough to keep it together if there is offset thrust or just wind shear, etc.

If you are going to use explosive bolts for stage separation, do you have a source where you can purchase off the shelf devices? I was looking and found hollow 5/16-24 bolts for $11.00 apiece. If we knew what size bolts that were going to be used, we could search for more accurate prices, or consider taking bolts and placing them in a vise and drill them ourselves in a drill press. You might even consider an oversize bolt made of nylon instead of steel so there is a less dense shrapnel at ignition so that it does not damage rocket components? I have no idea what the lead time for such things might be, so we might want to start working on this component also. You might also consider a steel cylinder or sleeve to slide the bolts inside of, so that it acts as a blast shield to protect other components, then you could use steel bolts.

If you are going to use explosive bolts for stage separation, do you have a source where you can purchase off the shelf devices? I was looking and found hollow 5/16-24 bolts for $11.00 apiece. If we knew what size bolts that were going to be used, we could search for more accurate prices, or consider taking bolts and placing them in a vise and drill them ourselves in a drill press. You might even consider an oversize bolt made of nylon instead of steel so there is a less dense shrapnel at ignition so that it does not damage rocket components? I have no idea what the lead time for such things might be, so we might want to start working on this component also. You might also consider a steel cylinder or sleeve to slide the bolts inside of, so that it acts as a blast shield to protect other components, then you could use steel bolts.

Nylon bolts per/ Kevin Trojonowski (spelling ??). They have the process down and have had great success on their BIG project the Delta III. see http://www.rocketryonline.com/rolpresents/index.php?site=insane&page=details

He will be sending me detail pics and data on the process soon.

From what I remember about the bolts, the more crudely they were drilled the better. A lathe was the least preferable tool to use to bore them out.

Edward

From what I remember about the bolts, the more crudely they were drilled the better. A lathe was the least preferable tool to use to bore them out.

Edward

Yep .. if it's too smooth the epoxy doesn't grab and the charge blows out vs blowing apart the bolt. You can thread the hole with a tap to be sure.

I was reading about pyrotechnic fasteners today on wikipedia. It mentions that besides the bolts being hollow, they were scribed all the way around so there was a weak point. I have a drill press and a machinists vise where I could drill the bolts out and if need be, and if the bolts are 1/2" or less in diameter, I could scribe a ring on the circumference of the bolt. If we had a good idea of how much stress would be place on these bolts, I could make some up with the hole drilled throught the center and then stress test them in a 10 ton press that I have access to. With a little effort, I can see how much it takes to pull them apart. Once we know that and engineer them to take the stress of the launch, it should not be hard to complete the operation and test a set of completed bolts.

This reminds me, how much voltage or how many batteries are going to be needed for this beast; how many payload compartments are going to be needed? Since we know there are chases that run the length of the rocket, on the outside, between rocket tubes, we could use those to run wiring, if you do not want to place it inside the tube to eliminate possible confusion.

For setting of the bolts, we could use the same sort of squibs that we make up for ejection charges, ( I am specifically thinking of the rocketflite ignitors), determine the number of bolts that will be used, and make sure we have enough amperage in our batteries to set those off and maybe a backup set of ignitors in each bolt, so that we need 2 separate firing circuits.

We will need on board batteries for firing 6 motors in the booster, then batteries and switches for all the electronics, whether timers or altimeters, or tiltometers; power for ejection charges and redundants, batteries for the bolts, batteries and electronics for the sustainer to ignite those motors, and then the regular dual deployment gear for the sustainer. I am presuming that Adrian is taking care of most of this. Or at least to tell us what we will need to make it happen. (My brain hurts 😕 )

What else?

Steve wrote:"Yep .. if it's too smooth the epoxy doesn't grab and the charge blows out vs blowing apart the bolt. You can thread the hole with a tap to be sure."

You could also do something that I have been successful with and that is place some recovery wadding over the charge and then hot glue to seal your container. This would also work if you tap the hole as descibed. You could also get some nylon all-thread and plug the hole, and then add CA to make sure it stays in place. The hot glue also works well to make sure the wires coming through are secured and air tight. I find it is much easier and faster than epoxy.

If you want to bore and then tap them a lathe would be perfect. A simple easy operation. Grooving the outside on a lathe would also be repeatable.

Edward

No need to reinvent the wheel on the bolts. Kevin Troj is sending me his well tested and flight proven exploding bolt specs so we'll start with that .. and then test it thoroughly of course.

Adrian has certainly showed an interest in helping and advising and I really appreciate that .. we will need it.

I was reading about pyrotechnic fasteners today on wikipedia. It mentions that besides the bolts being hollow, they were scribed all the way around so there was a weak point. I have a drill press and a machinists vise where I could drill the bolts out and if need be, and if the bolts are 1/2" or less in diameter, I could scribe a ring on the circumference of the bolt. If we had a good idea of how much stress would be place on these bolts, I could make some up with the hole drilled throught the center and then stress test them in a 10 ton press that I have access to. With a little effort, I can see how much it takes to pull them apart. Once we know that and engineer them to take the stress of the launch, it should not be hard to complete the operation and test a set of completed bolts.

This reminds me, how much voltage or how many batteries are going to be needed for this beast; how many payload compartments are going to be needed? Since we know there are chases that run the length of the rocket, on the outside, between rocket tubes, we could use those to run wiring, if you do not want to place it inside the tube to eliminate possible confusion.

For setting of the bolts, we could use the same sort of squibs that we make up for ejection charges, ( I am specifically thinking of the rocketflite ignitors), determine the number of bolts that will be used, and make sure we have enough amperage in our batteries to set those off and maybe a backup set of ignitors in each bolt, so that we need 2 separate firing circuits.

We will need on board batteries for firing 6 motors in the booster, then batteries and switches for all the electronics, whether timers or altimeters, or tiltometers; power for ejection charges and redundants, batteries for the bolts, batteries and electronics for the sustainer to ignite those motors, and then the regular dual deployment gear for the sustainer. I am presuming that Adrian is taking care of most of this. Or at least to tell us what we will need to make it happen. (My brain hurts 😕 )

What else?

As I recall we had 100% success with the exploding bolts on the Delta II project. We should use the same technology again.

As I recall we had 100% success with the exploding bolts on the Delta II project. We should use the same technology again.

We didn't actually use bolts on the Delta .. we connected the boosters using 2 pvc endcaps .. one inside the other .. and the charge inside them. That worked to secure and stabilize the boosters.

These are needed to secure 2 bulkheads together (flush). I'll have some pics of the process soon.

For the exploding bolts, I'd recommend Quest Q2G2 ignitors because we can run as many bolts in parallel off of one electrical output as we want.

For the booster, I could make up a couple of small plywood sleds that have the Ravens with Power Perches and batteries, and mail them to you guys for installation. The sleds could be installed anywhere that puts one edge within 2.5" of the outside and that has some venting to ambient. No hatches or switch holes are required, and the last access to top off the batteries can be up to a couple of weeks before the launch. On each outboard we can either put an arming switch on each one at the back end of the airframe, or just wait to install/connect the outboard ignitors until the rocket is upright and recovery electronics are armed.

For the sustainer, I don't know enough about the Tiltometer or the sustainer recovery plan yet to suggest a configuration. We'll want a GPS also.

I am unable to find my copy of Rocksim from several years ago, on CD, since I moved in Aug .. and so much stuff went into storage. I d/l'd a trial of the new version but it has timed out and I can't afford to buy it now.

just sayin' ... 🙂

Also, I need some 38mm MMT's .. 3 @ 12" or so and 1 - 54mm @ 12" or so. Anyone .. anyone ..

Any thoughts on adding motors to the 3rd stage .. a small blackjack or something like that for effect. We will already be separating the 3rd stage for recovery purposes .. so .. just thinkin' out loud .. 😉

Steve, I was going to get some nylon bolts, drill a hole in the hex head, then scribe the circumference 1 1/2" down from the head on the outside, in the threads. I was thinking of placing powder and two redundant ignitors and then sealing the hole up with wires coming out. I was also going to drill holes the diameter of the bolts in two pieces of 3/4" plywood, bolt them together and try the bolts out in my bar-b-que pit. What size bolts are you thinking of?

Steve, I was going to get some nylon bolts, drill a hole in the hex head, then scribe the circumference 1 1/2" down from the head on the outside, in the threads. I was thinking of placing powder and two redundant igniters and then sealing the hole up with wires coming out. I was also going to drill holes the diameter of the bolts in two pieces of 3/4" plywood, bolt them together and try the bolts out in my bar-b-que pit. What size bolts are you thinking of?

Kevin hasn't gotten back to me yet, but I'd think pretty big ... 5/8 or so? needs to be something we can easily drill and get 2 igniters in ... and would hold this big stuff together.

get some video of it if you can..

Thanks!