Two-stage HPR design build

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I just bought the FeatherWeight Raven Black Saturday deal. So, that settles it, the sustainer will be flying with the Raven and the MissileWorks WRC+ in the av-bay. Earlier today I ordered an Adept22 alt for the booster. I plan on placing the Adept in the forward transition of the booster...

Sounds like a good set up.
 
Made some progress over Thanksgiving break. As shown in the previous posts above, the booster is coupled to the sustainer using a set of three rods/receiver sleeves. The rods protrude out of the top of the transition coupler as pictured below. The transition will also serve as the av-bay for the booster (as can been seen in the third thumbnail)...

Reebok Comet VXS2 Booster.jpg

stage coupler components.jpg

rods in av-bay.jpg

Rods.jpg
 
The pics below are of the transition aft bulkhead. The three rods protrude through the bulkhead so that it can be secured with wingnuts for ease of assembly/access. The green cylinder is a holder for a CO2 cartridge. I've decided to use my RouseTech CD-3 hardware for deployment (I had several of the small 12g cartridge holders left from a previously abandoned design). The bulkhead is made from three concentric disks, the av-bay tube fits over the small 3" disk, the middle sized disk fits into the shoulder of the PML transition, and the larger disk fits into the booster airframe...

bulkhead 1.jpg

bulkhead2.jpg

bulkhead with af-bay.jpg

transition with aft bulkhead.jpg
 
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Hi Bret,

Your order goes out tomorrow and I've included a surprise that should garner attention on this project.

Kent/GLR
 
Okay, I'm beginning to turn my attention to the sustainer. Before I can get the transition/coupler "rods" properly aligned with the sustainer coupler "sleeves," I need to get the geometry of the coupler components nailed down. As I fabricated the centering rings for the transition av-bay and the sustainer, I stacked them all up in a concentric pile (all aligned inside a short segment of 3" Bluetube airframe) on my drill press and drilled all the holes for the "rod/sleeves" simultaneously. This was done so that everything would align, hopefully in a manner that will allow the booster to drag separate following booster motor burnout. I'm still not fully convinced this is going to work 'cause I'm making this up as I go. The pics below show what I'm talking about, 1) sleeve holes located in between fins, 2) aft two CRs spaced to accomodate fin tabs (forward end of sleeve tubes are plugged), note: small black tube is the sustainer ingniter wire conduit, and 4) another view...

Rod positions.png

sustainer coupler subassembly.jpg

MMT CRs etc.jpg

MMT CRs.jpg
 
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Back to the other end for a moment... The fillets on the six fins of the booster are completed. Doing fillets on fins that span a reducer/transition were slightly more challenging than the typical fillet, but they all turned out nicely. The booster fin can is complete and ready for primer and paint.

booster fillet.jpg

booster fillet2.jpg

Booster Fin Can.jpg

Booster complete.jpg
 
Here's one of the most unusual assembly techniques (for mounting blind T-nuts into which rail guides are screwed down) that I've ever used. For previous designs I've simply glued a strip of hardwood to the MMT, then drilled pilot holes and used wood screws to attach the rail guides. In this case I had already drilled holes and used JB Weld to attach T-nuts to a strip of plywood, so I decided to figure out how to make it work. The approach was, different and a bit tedious, but it worked out just fine. Since I had already assembled the MMT with the CRs (and the staging coupler sleeves and the sustainer igniter conduit) as a solid unit I had to partially insert that subassembly into the sustainer airframe, then slide the plywood/T-nuts in between the aft CRs (using the tape tab) and screw down the rail guide to it prior to fully inserting the MMT/CR assembly. I stuck a strip of painter's tape (forming a removable tab) on the bottom of the plywood strip and put some epoxy on the top side. After sliding the plywood strip into place with the tape tab, I used a flashlight and a toothpick and alinged the t-nuts with the holes in the airframe, inserted a machine screw through one of the holes and screwed it into a t-nut. Using the machine screw I then pulled the plywood strip up into position causing the epoxy to stick the strip in place inside the airframe. While the expoxy was still soft I screwed the rail guide with both machine screws into place, pulled the tape tab off, and allowed the epoxy to set up while I added epoxy inside the airframe then slid the MMT/CRs into place. I'm pretty sure the above description is confusing and am hoping the pics below add clarity...

Rail Lug T-nut Standoffs.jpg

rail lugs tnuts mount.JPG

rail lugs tnuts mount2.jpg
 
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Steely,
In the above pics, what's the extra hardware just under the motor retainer?

ZS

Hey Zach,
I was going to get to that... Here's a couple additional pics that show it better. I put two #10-24 machine screws through the aft CR (one on either side of the igniter conduit). On each screw I added a washer, lock washer, and nut to keep the screws in place on the CR and to attach a terminal to which the igniter leads are soldered (the other end of the lead wires will be attached to the WRC+ 2nd stage ingnition output in the av-bay). Then I added another nut and a 10-24 thread coupler. My intention is to use two 10-24 screws in the end of the tread couplers as screw posts to attach the igniter wires for the upper stage motor. The main reason for all this added complexity was to make it convenient to attach the igniter wires out at the pad (I could have used the twist and tape method, but that's not my preferrence). I did not want to have to run igniter wires through the conduit, open the av-bay, attach the wires within it, close the av-bay, pack the drougue chute, and insert shear pins at the pad (rules prohibit inserting the igniters until you're at the pad). Like I've said earlier in this post, I have not built or flown a 2-stage HPR. If anyone has any clarifying advice to offer... I'm all ears.

Bret

Sustainer screw posts2.jpg

sustainer 1st fin.jpg
 
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Hey Zach,
I was going to get to that... Here's a couple additional pics that show it better. I put two #10-24 machine screws through the aft CR (one on either side of the igniter conduit). On each screw I added a washer, lock washer, and nut to keep the screws in place on the CR and to attach a terminal to which the igniter leads are soldered (the other end of the lead wires will be attached to the WRC+ 2nd stage ingnition output in the av-bay) . Then I added another nut and a 10-24 thread coupler. My intention is to use two 10-24 screws in the end of the tread couplers as screw posts to attach the igniter wires for the upper stage motor. The main reason for all this added complexity was to make it convenient to attach the igniter wires out at the pad (I could have used the twist and tape method, but that's not my preferrence). I did not want to have to run igniter wires through the conduit, open the av-bay, attach the wires within it, close the av-bay, pack the drougue chute, and insert shear pins at the pad (rules prohibit inserting the igniters until you're at the pad). Like I've said earlier in this post, I have not built or flown a 2-stage HPR. If anyone has any clarifying advice to offer... I'm all ears.

Bret

That is a great idea,I like it.Much better than what I am doing on my Quantum Leap.I have one wire that runs from the AV bay,through the drogue section (it has a break in it so when the drogue charge fires the wires pull apart) out the aft centering ring where the igniter and separation charge are connected.I could not do what you are doing because the aft centering ring on the sustainer is 3.5 inches inside the body tube.I also think your club should allow the igniter for the sustainer to be installed during prep,this would make it much easier at the pad.
 
That is a great idea,I like it.Much better than what I am doing on my Quantum Leap.I have one wire that runs from the AV bay,through the drogue section (it has a break in it so when the drogue charge fires the wires pull apart) out the aft centering ring where the igniter and separation charge are connected.I could not do what you are doing because the aft centering ring on the sustainer is 3.5 inches inside the body tube.I also think your club should allow the igniter for the sustainer to be installed during prep,this would make it much easier at the pad.

I appreciate the feedback. Frankly, I don't know what is allowed by the clubs that I fly with, regarding installation of igniters for two-stage designs. Because I have never flown one, I have not thought to ask the question yet.

I would be interested in seeing details of your project. Is there a thread posted? I don't have a separation charge planned on this bird, as I am counting on drag separation (still hoping this works... if it doesn't drag separate I don't plan on igniting the upper stage... shortly thereafter, the main on the boster would deploy as well as the drogue on the sustainer... I'm guessing that might pull them apart by then... and the main on the sustainer would ultimately deploy when I hit the button or it falls below 300 ft.)

Also, similar to what you are describing, the igniter wires on this bird must break apart at apogee (this is a DD design with the drogue in the middle). To accomplish that I am using a two-conductor plug (I found it at my local Hobbytown, in the section for RC car stuff). It will reside in the compartment with the drogue chute. I will post photos of it when I get to that part of this build.

Cheers,
Bret
 
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Hey Zach,
I was going to get to that... Here's a couple additional pics that show it better. I put two #10-24 machine screws through the aft CR (one on either side of the igniter conduit). On each screw I added a washer, lock washer, and nut to keep the screws in place on the CR and to attach a terminal to which the igniter leads are soldered (the other end of the lead wires will be attached to the WRC+ 2nd stage ingnition output in the av-bay). Then I added another nut and a 10-24 thread coupler. My intention is to use two 10-24 screws in the end of the tread couplers as screw posts to attach the igniter wires for the upper stage motor. The main reason for all this added complexity was to make it convenient to attach the igniter wires out at the pad (I could have used the twist and tape method, but that's not my preferrence). I did not want to have to run igniter wires through the conduit, open the av-bay, attach the wires within it, close the av-bay, pack the drougue chute, and insert shear pins at the pad (rules prohibit inserting the igniters until you're at the pad). Like I've said earlier in this post, I have not built or flown a 2-stage HPR. If anyone has any clarifying advice to offer... I'm all ears.

Bret

I can't use "terminals" like you have on my two-stagers, but in looking at yours, it occurs to me that such an approach might allow the use of a shunt. The shunt could be connected to the booster and the terminals such that the parts would have to separate and break the shunt before the sustainer could be lit. It might be better to do this with a separation charge. I hear stories from time to time about sustainer motors lighting on the ground and I know someone that was injured by that. A shunt would provide one more layer of safety. I'm going to see if I can figure out a way to do this on my two stagers.

Jim
 
Jim,
That's a great idea for added safety. I could fabricate (from piano wire, brass shim stock, or maybe copper contacts from an old flashlight or other battery powered device) something to attach within the top of the booster airframe that would make electrical contact between the two threaded couplers. While the booster and sustainer stages are still in contact with each other, that would effectively short out the current that would otherwise ignite the upper stage (preventing ignition while the stages are coupled). Then after separation... no short... everything should work as designed. The only concern is my ability to still achieve drag separation with this safety device in place. I will explore this approach. Thanks for a great suggestion!

Bret

Another thought, after this was initially posted. A short is not as effective as a shunt, because the igniter would still be in a parallel circuit with the shorting device, although the vast majority of the current would pass through the short. The question would be is there still sufficient current that would/could fire the igniter. I will have to do some testing to make sure the approach has the desired result...
 
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Wow.

This is an awesome thread.

How are you going to wire the ignitor to the e-bay? Are you just going to run the ignitor up through the rocket or use a glued in wire system? This is how I wired my Thunder and Lightning to light the sustainer from the top. I used banana plugs and conduits up through the rocket, and I found it easier to glue the plugs and conduits into a sleeve before I glued it into the rocket. The plus about doing it this way is that I included a microswitch so I could disconnect the ignitor until everything proved to work, and it's a zipperless setup.

Pone133.jpg


Pone128.jpg
 
Brian,

I like the banana plug idea!

-Tim

Wow.

This is an awesome thread.

How are you going to wire the ignitor to the e-bay? Are you just going to run the ignitor up through the rocket or use a glued in wire system? This is how I wired my Thunder and Lightning to light the sustainer from the top. I used banana plugs and conduits up through the rocket, and I found it easier to glue the plugs and conduits into a sleeve before I glued it into the rocket. The plus about doing it this way is that I included a microswitch so I could disconnect the ignitor until everything proved to work, and it's a zipperless setup.

Pone133.jpg


Pone128.jpg
 
Wow.

This is an awesome thread.

How are you going to wire the ignitor to the e-bay? Are you just going to run the ignitor up through the rocket or use a glued in wire system? This is how I wired my Thunder and Lightning to light the sustainer from the top. I used banana plugs and conduits up through the rocket, and I found it easier to glue the plugs and conduits into a sleeve before I glued it into the rocket. The plus about doing it this way is that I included a microswitch so I could disconnect the ignitor until everything proved to work, and it's a zipperless setup.

Brian,
Thanks, glad you like the thread. To answer your question, I haven't actually made up my mind yet. I'm still considering alternatives, but my latest thinking is to utilize a small, 2 conductor plug (from an RC car application) that will reside in the drogue compartment. I will post some pictures when I get to that part of the build. BTW, I like your solution to this problem, it challenges me to think more creatively.

Bret
 
Been working on the bird a bit, but hadn't had time to post. I started this project a bit dissappointed with my latest shipment of Bluetube, because the coupler tubes fit within the airframe was extremely loose (so much so that if you dropped the Bluetube coupler into one end of the Bluetube airframe it would fall all the way through). This was true with both the 3" and 4" tubing I recently received. I have never had this happen before (it has usually been a firm, smooth fit). I was anxious to get started over Thanksgiving break so I decided to proceed anyway. I got so far along with the booster that I finished it with the "loose" Bluetube (because it was all going to be shear pinned anyway). Now that it's done, I think it will work fine, but it could have been better. As I began the sustainer I decided to order some 3" GLR Magna-Frame airframe tubes just because I was dissapointed with the Bluetube and was looking for a good reason to try the GLR product.

I received my order from GLR over the weekend and am most pleased with the Magna-Frame tubing. It looks and feels superior to the Bluetube. While I was waiting on the GLR order to come in I continued working on the sustainer with the loose Bluetube, thinking I would build another copy of it when the Magna-frame arrived. In the mean time I decided to build another sustainer out of GLR Magna-Frame that will fly with this booster design. To make it interesting I created another unique design for a new sustainer (a hyper-velocity space plane looking design) that I plan to build out of GLR M-F airframe (more to come on this later).

The surprise added to my package was a 3" Dyna-Wind airframe tube (made by compression bonding a glassed Magna-Frame). I must say "WOW!" I am beyond impressed. This stuff is amazingly light and appears indestructable. The finish is... well smooth as glass. For future projects I may never fill another tube spiral again. All that's required is running my mouse sander down the seam (from the compression bonding process) to get it ready for building. Thanks Kent, I'm looking forward to working with this product! It looks like I have a new favorite airframe material. But now I want to come up with a more high performance design that will be worthy of this new Dyna-Wind product (I'm thinking about a minimum diameter kinetic energy penetrator looking design for a future project). Anyway work will continue on this project and more pics will be posted in the next day or two...
 
Been working on the bird a bit, but hadn't had time to post. I started this project a bit dissappointed with my latest shipment of Bluetube, because the coupler tubes fit within the airframe was extremely loose (so much so that if you dropped the Bluetube coupler into one end of the Bluetube airframe it would fall all the way through). This was true with both the 3" and 4" tubing I recently received. I have never had this happen before (it has usually been a firm, smooth fit). I was anxious to get started over Thanksgiving break so I decided to proceed anyway. I got so far along with the booster that I finished it with the "loose" Bluetube (because it was all going to be shear pinned anyway). Now that it's done, I think it will work fine, but it could have been better. As I began the sustainer I decided to order some 3" GLR Magna-Frame airframe tubes just because I was dissapointed with the Bluetube and was looking for a good reason to try the GLR product.

I received my order from GLR over the weekend and am most pleased with the Magna-Frame tubing. It looks and feels superior to the Bluetube. While I was waiting on the GLR order to come in I continued working on the sustainer with the loose Bluetube, thinking I would build another copy of it when the Magna-frame arrived. In the mean time I decided to build another sustainer out of GLR Magna-Frame that will fly with this booster design. To make it interesting I created another unique design for a new sustainer (a hyper-velocity space plane looking design) that I plan to build out of GLR M-F airframe (more to come on this later).

The surprise added to my package was a 3" Dyna-Wind airframe tube (made by compression bonding a glassed Magna-Frame). I must say "WOW!" I am beyond impressed. This stuff is amazingly light and appears indestructable. The finish is... well smooth as glass. For future projects I may never fill another tube spiral again. All that's required is running my mouse sander down the seam (from the compression bonding process) to get it ready for building. Thanks Kent, I'm looking forward to working with this product! It looks like I have a new favorite airframe material. But now I want to come up with a more high performance design that will be worthy of this new Dyna-Wind product (I'm thinking about a minimum diameter kinetic energy penetrator looking design for a future project). Anyway work will continue on this project and more pics will be posted in the next day or two...

Bret, I'm glad you like the product. If you really want to amp it up, have me slot plus cut your g10/carbon fins and bevel them. People who have me bevel for them find out the necessity of having Kleenex around because they are so-so sharp.
 
Have been working on the booster av-bay. As mentioned earlier, I'm using and Adept22 for single apogee deploy and the Featherweight magnetic switch. Got it all wired up and working (without plastic PML transition installed over the av-bay). After I put it all together and installed the av-bay within the PML transition, the extra 1/2" (or so) of thickness, my magnet was not strong enough to acuate the Featherweight switch. Worked great when it was just within the 3" coupler tube. Just ordered a more powerful magnet (easier than reworking my av-bay). Pics below...

adept22 and bulkhead.jpg

avbay parts.jpg

avbay wired.jpg

avbay enclosed.jpg

booster finished.jpg
 
Here's the interstage coupler with the av-bay inside the PML transition. After I got it all together I realized that I can shorten the all-thread rods by 3/4 of an inch or so...

interstage coupler complete.jpg
 
Spent most of my build time today doing fillets on the sustainer and the shear plates for the middle (drogue) airframe separation. The sustainer is starting to look like a rocket. It will really look cool when I get the "ramjet intake" tubes on the lower, aft fins. Will post some pics tomorrow. Gotta get some sleep...
 
Okay, the weekends over and I'm posting a few pics and watching the season finale of Survivor.

Some pics mentioned yesteday... some fillets on the sustainer and the shear plates on the coupler/baffle. Note that the coupler in "keyed" so that the hole for the igniter conduit will align properly in the pre-drilled hole.

sustainer fin fillet.jpg

canard fin fillet.jpg

baffle bulkhead coupler.jpg

sustainer baffles.jpg
 
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I know you've probably heard this from a lot of people, but this rocket is awesome. I love your design, attention to detail and craftsmanship that you've put into this. Definitely following this thread.

Peter
 
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