[B]Introduction to Staging[/B]

[NorthwoodsRockets]

I am looking for advice on a kit to enter high power staging. A friend suggested I start with the PML Quantum Leap with CPR. There is also the Thunder –N– Lightning from Public Missiles. But, I think I prefer the Mini-BBX w/ CPR3K and Terrier Booster. Even though the “Tim The Tool Man Taylor” in me says bigger is better, I like that the BBX/Terrier is less expensive, flies on smaller motors, and I only need one set of each size hardware.
While I have been building model rockets, on and off, since the 70’s, and have built the Echostar, Commanche 3, and CC Express staged model rockets, I have only been in high power rocketry for about two years. I earned my level two certification two summers ago on a PML AMRAAM-4. It later survived flight to 5,623 ft on a K550. I spent last year building and flying an upscale Orbital Transport - ultimately on a J460 with four G77s air-started in the scramjets. I have a Cirrus Dart and Eagle Claw 4 yearning to be put together this spring. I would also like to build and fly a HPR two-stage rocket this summer.
What is the best kit to learn staging with? Would you go with the PML kits or is there something else out there I should suggest? Would you modify the kit? I am not a fan of Quantum Tubing, so, regardless of the kit, I would order it with phenolic body tubes (probably pre-glassed). I do like to push the performance envelope and the AMRAAM-4 tried to shed a fin under the power of the K550. Therefore, I also lean toward going up to the next thickness G10 fin or tip-two-tip glassing the fins.
Thanks for the help,
Matt

[bobkrech]

I am looking for advice on a kit to enter high power staging. A friend suggested I start with the PML Quantum Leap with CPR. There is also the Thunder –N– Lightning from Public Missiles. But, I think I prefer the Mini-BBX w/ CPR3K and Terrier Booster. Even though the “Tim The Tool Man Taylor” in me says bigger is better, I like that the BBX/Terrier is less expensive, flies on smaller motors, and I only need one set of each size hardware.
While I have been building model rockets, on and off, since the 70’s, and have built the Echostar, Commanche 3, and CC Express staged model rockets, I have only been in high power rocketry for about two years. I earned my level two certification two summers ago on a PML AMRAAM-4. It later survived flight to 5,623 ft on a K550. I spent last year building and flying an upscale Orbital Transport - ultimately on a J460 with four G77s air-started in the scramjets. I have a Cirrus Dart and Eagle Claw 4 yearning to be put together this spring. I would also like to build and fly a HPR two-stage rocket this summer.
What is the best kit to learn staging with? Would you go with the PML kits or is there something else out there I should suggest? Would you modify the kit? I am not a fan of Quantum Tubing, so, regardless of the kit, I would order it with phenolic body tubes (probably pre-glassed). I do like to push the performance envelope and the AMRAAM-4 tried to shed a fin under the power of the K550. Therefore, I also lean toward going up to the next thickness G10 fin or tip-two-tip glassing the fins.
Thanks for the help,
Matt

If you're pushing a PML kit, definitely get the preglassed phenolic, and upgrade the fins at least one thickness, and if you're really pushing the velocity, two thicknesses on the upper stage to prevent fin flutter.

Bob

[JDcluster]

Definitely go with thicker fins!
I've seen videos of where a stock Quantum Leap tore itself apart due to fin flutter. I'd even go so far to glass it.

They are quite involved and I like them for that reason. I have 2 sitting on the bench needing some more attention to the electronics sections.


JD

[Eric1]

Definitely go with thicker fins!
I've seen videos of where a stock Quantum Leap tore itself apart due to fin flutter. I'd even go so far to glass it.

They are quite involved and I like them for that reason. I have 2 sitting on the bench needing some more attention to the electronics sections.


JD

What epoxy did you use to glass the q-tube? I have a BBX and I don't feel comfortable about the material, considering some of the motors I plan to fly.

[Marsman]

I'm documenting my L3 project here, http://www.flickr.com/photos/57507662@N08/

which also happens to be the sustainer stage of a 4" M to M rocket. The booster is an Extreme Darkstar fin can and the sustainer is scratch (PR and Wildman components).

Right now I'm focusing mostly on the L3 side of things, but the design of the upper stage is dictated by the two stage configuration. You might be able to get some ideas off of my build.

Both stages are dual deploy, the booster is dual deploy out of a single tube using pyro bolts to hold the deployment bag to the forward bulkhead. The booster has an ALTACC 2A for deployment and a Perfectflite Minitimer for stage separation.

The upper stage has a Raven for air start and deployment, and an RRC2 mini for backup deployment. I'm using a BRB900 tracker in the nose cone.
I'm shooting for 20k on a CTI M2250 to a CTI L640 for its first flight.

I'm running the wires for the igniter down a plastic conduit from the sustainer av bay. CTI 54mm and under motors have the "instant on" starter pellet in the top of the motor, making ignition with the supplied (or my own) e-match a breeze.

[CF-105]

What epoxy did you use to glass the q-tube? I have a BBX and I don't feel comfortable about the material, considering some of the motors I plan to fly.

Yeah, QT is not meant for anything more than "normal" sport flying. I saw someone attempt to fly a BBX on an M1400 once. They'd reinforced the airframe with an internal phenolic coupler tube, to reduce flexing. Didn't help - somewhere near the end of the burn, the rocket disintegrated.

[JimJarvis50]

I've made a number of posts over time with my opinions on the QL. So, I'm just going to do the crib notes version, and you can search and find a lot of info on this rocket. Here are some suggestions.....

- Everyone should have a 3" two-stager. Go with the QL concept, but with modifications.
- The glassed phenolic is fine. It's pretty easy and a whole lot less expensive to do it yourself though. There are lots of resources on how to do it.
- Get thicker fins. The stock fins are ... , well, they're not good. Go at least 0.093 or even 0.125. The sustainer fins can be reduced in size a little, which helps reduce flutter.
- Ditch the CPR and interstage stuff. Go with a conventional altimeter bay and light the sustainer from above.

My QL clone is pretty strong, but I'm not particularly interested in flying it above Mach. But with the long burn motors, there are options where the speed isn't that great. My favorate flight is a K940 to a K160 - both 54mm 4 grain motors. Those are the largest motors that will fit (although I'm not positive that this is true for the stock kit). Mine will do 14K without going over Mach 0.75 or so. I did a slightly smaller flight a few weeks ago with a J1520 in the booster, except the ejection charge didn't go and the booster lawn darted. I'm going to rebuild the booster (fin portion is still just fine) and I'm going to extend the booster to allow bigger motors - probably a 54mm 6-grain. Parts are on the way to the house as we speak.

Jim

[rocketboy16]

Jim, or anyone who can answer.

As you build this new booster, do you think you could take some pictures so that we can see the inter-stage coupler design? I have only seen this done previously for minimum diameter rockets where the sustainer is used as a coupler. So i do not fully understand what all is going on with the timers and coupler tubes etc.

Thank you

Peter

[NorthwoodsRockets]

Jim,
I second Peter's request. There is some great advice above, but you are a rocket god to me. (Sorry to gush.) I am working on a dual-deploy Cirrus Dart that I hope to ultimately fly on Loki J1000 and maybe the sustainer of a two-stage. The Jarvis Illustrated Guide to Carbon Fiber
Construction is my bible. Your craftsmanship is extraordinary.
A picture is worth a thousand words. I'd love to see how you put a two-stage together. I thought I had searched for all your posts but I'll look again for two-stage stuff.
Thanks,
Matt

[bobkrech]

What epoxy did you use to glass the q-tube? I have a BBX and I don't feel comfortable about the material, considering some of the motors I plan to fly.

Please read the PML FAQ. Carefully.

Although PML has made QT standard on most of their kits, PML specifically tells you not to glass QT, and not to use it over M=0.85.

If you are planning flights over that velocity, PML recommends that you order phenolic airframe and thicker fins.

http://www.publicmissiles.com/images/pmlalti.pdf This motor selection sheet tells you what motors require phenolic tubing and thicker fins.

http://www.publicmissiles.com/images/PMLCompleteFAQ.pdf This is the complete PML FAQ. It tells you what you have to do to modify your rockets and why you have to do it. It specifically tells you not to glass QT kits.

Bob

[JDcluster]

I never purchased a PML Quantum Leap or any of their 2 stage kits. PML even suggests using phenolic when glassing.

I scratch built all of my 2 stage rockets except for the last one which was a kit bash of 2 PR kits



JD

What epoxy did you use to glass the q-tube? I have a BBX and I don't feel comfortable about the material, considering some of the motors I plan to fly.

[JimJarvis50]

Jim,
I second Peter's request. There is some great advice above, but you are a rocket god to me. (Sorry to gush.) I am working on a dual-deploy Cirrus Dart that I hope to ultimately fly on Loki J1000 and maybe the sustainer of a two-stage. Your HighCarbYen is my bible. Your craftsmanship is extraordinary.
A picture is worth a thousand words. I'd love to see how you put a two-stage together. I thought I had searched for all your posts but I'll look again for two-stage stuff.
Thanks,
Matt

Well thanks. In response to your kindness, allow me to provide a picture of me on my god-like podium before launching my QL clone (note the clipped fins on the sustainer). The rocket weathercocked and flew off a mile to the south - not its best flight.

To make the new booster, I'll cut the damaged section off a few inches above the fins and glue on a new section of airframe. The staging coupler is no big deal though. The bottom half of the sustainer fins are surface mounted, so a standard 75mm coupler can slide up into the sustainer. I'll probably use about an 8" section of coupler tube. It will have a 1" piece of airframe glued to it to position it between the sustainer and the top of the booster. Then, there will just be a bulkhead in the middle of it. The only thing novel is that I will line the inside with carbon and then I'll glue the bulkhead inside of that. There's no electronics in it though - just motor deploy with the sustainer lit from above.

Now, I do have a two stager that's a little more innovative. If you wouldn't mind me highjacking your thread, I could post some pics.

Jim

[atxcple]

Now, I do have a two stager that's a little more innovative. If you wouldn't mind me highjacking your thread, I could post some pics.

Jim

do i hear that zen like sound of too carb yen

[NorthwoodsRockets]

If you wouldn't mind me highjacking your thread, I could post some pics.

Jim

Please highjack away!

[JimJarvis50]

Please highjack away!

OK, here goes.

The rocket in question is "Some Assembly Required". It's an almost-minimum-diameter rocket - 4" and about 15' tall. It flew at Balls last year on an N4000 / N1100 combination (see the pre-launch pic below). Unfortunately, something bad happened right at the end of the sustainer burn. It was at 30K and Mach 2.3 at the time, and the "event" is at 5:26 in this video.

http://www.youtube.com/watch?v=EBSyIZQj4LM

Most of the key pieces of the rocket of the rocket were recovered, and I have just completed a rebuild. I used several different construction techniques on the rebuild, which will be documented in a separate article. But the appearance and general function is the same. I decided to make a new booster in addition to the sustainer, and I'll post some booster pics next.

Jim

[JimJarvis50]

Here are some pictures of the booster, mainly of the area between the two motors. This is the most interesting part of the rocket.

Pic 1 is of the booster fin section and the motor. I make the tubes a little oversized, so the motor actually fits up into the coupler.

Pic 2 is of the sustainer motor. It has a piece of electrical wiring on it that carries the charge for the igniter and the separation charge. The wire actually travels up the whole motor, but this is just for illustration.

Pic 3 shows a sleeve placed over the motor. This sleeve will center the motor in the sustainer fin section and this part of the motor then serves as the interstage coupler. The booster's upper airframe section just barely fits over this conduit.

Pic 4 shows the sustainer motor installed into the sustainer. Below that is what I'll call a chute cannon. It contains a piston, the chute , a D-bag, a pilot chute and the harness. The little nose plug goes on top of the chute cannon and protects the chute from the separation charge and from the wind after the sustainer has departed. It gets shear pinned into the chute cannon, and then the shear pin heads are cut off so that the lower airframe section can later slide over the top.

Pic 5 shows how the whole assembly fits together.

(Continued)

Jim

[JimJarvis50]

(Continued)

The next few pics start from below the chute cannon and work upwards.

Pic 6 shows a shelf installed into the airframe tube between the booster and sustainer motors. The booster altimeter bay sits on this shelf. There is no tube break.

Pic 7 shows the booster altimeter bay. It gets bolted to the shelf.

Pic 8 shows how the altimeter skid fits into this bay. There's just enough room for two MAWDs and two batteries.

Pic 9 shows the altimeter bay and the chute cannon connected together. This entire assembly gets prepped externally and then it slides into the booster's upper airframe and gets bolted to the shelf below.

Pic 10 shows the chute cannon assembly in position in the tube, and the sustainer with the motor/coupler just slides in on top of it.

This three-foot area between the two motors is pretty much everything that makes this rocket into a two-stager.

Jim

[Blackfly]

+1 for the best thread hijack ever.. Thank for those, Mr. Jarvis.