High Power 2-Stage build thread

I’m taking the leap into the realm of Multi-Stage High Power Rocketry. I know there are many ways to configure air-starts and deployments. So, with some research and a little common sense, here’s what I came up with…

The rocket will be scratch built using 3” diameter LOC Precision tubing (with 2 layers of 5.79 oz. fiberglass). The fins will be 1/8” plywood (with 1 layer of 5.79 oz. fiberglass for strength). The booster and sustainer will both have 38mm MMTs.

I am using 2 LOC AV bays (one for the Sustainer and one for the booster). I know it adds weight and might not be the most practical configuration. However, I have a lot of experience with this type of set up and want to keep it simple for my first 2 stage build.

The sustainer AV bay will be rigged for dual deployment with 100% redundancy using 1x SL100 and 1x RRC3 Xtreme Altimeter. The RRC3 has a configurable third “Aux” output (for air-starts) with a variety of safety features to ensure the rocket is pointing in the right direction before the sustainer is lit. (Thanks Dave / DavDue).

I plan to run 1/4” stainless steel tubing through the center rings and up the sustainer airframe to just shy of the AV bay. A set of wires will be attached to some form of release clip and run down through the ¼ tube to the Sustainer Igniter. (Thanks John / aka Droopy).

Inside the Booster AV bay will be 1x SL100 Altimeter and 1x Perfect Flight timer. The timer will be used to ignite a separation charge that will extract the booster from the sustainer. (Thanks Jim / aka JimJarvis). The Altimeter will be set to deploy a Booster chute.

A section of 3” body tube will be attached to the top of the Booster AV bay (using plastic rivets). A LOC coupler will be epoxied on top of that. This is what will slide into the sustainer and hold the 2 stages together.

The booster chute will be packed below the AV bay and above the MMT. I will pack a single charge to ignite at Booster apogee.

BTW – I am going to cheat a little on the Booster build. Instead of starting from ground zero, I will chop up an existing scratch built 3” glassed rocket and use that. Here’s a picture of it (before being subjected to the Dremel)…



The sustainer will be built from scratch. Build thread pictures coming soon.

Chris

Sweeeeet

Getting the booster ready was relatively simple...

Used tape as a guide to cut the Booster down to size...





Transferred an AV bay from a different 3" Dual Deploy rocket. I will be re-rigging the bay with 1x timer (for booster separation) and 1 altimeter (for Booster chute deployment).



Cut the Booster 'Payload' section down to size and slipped it on top of the AV bay. This will be secured to the AV bay with removable rivets.



Epoxied LOC Coupler on top of Booster Payload section.

For the sustainer - - I started by stripping the outer layer of the airframe and payload tubes and applied two wraps of Fiber Glass. Here they are with a wrap of peel ply (waiting to dry)...



I also cut the fins. As you can see, they are 'through the wall'. However, you need to off-set the fin-tabs enough to allow the Booster Coupler to fit in the bottom of the Sustainer...



Prepping to fiberglass the Sustainer Fins (sitting on parchment paper)...



Used West Marine Epoxy and applied 1 layer of FG. Then used a sheet of peel-ply...



During the curing process, I sandwich the fins between 2 panes of 1/4" glass. I also add additional weight. This ensures the fins are perfectly flat when dry...

The fins are dry and ready to be cut out of the glass...



A little Dremel work and here they are. I'll need to do a little filling/sanding to make them look nice...

Sanded down the body tubes and used filler where necessary...





A couple more steps...

1. Cut the fin-slots... I used a diamond blade on my Dremel and a steady hand
2. Cut a Vent Band for the Upper AV Bay - this came from some scrap on the original rocket that was used to build the booster

Here it is pieced together...

WOW you are moving along fast Chris. I like your design. Doesn't look like it will be to complex to fly.

Getmore said:

WOW you are moving along fast Chris. I like your design. Doesn't look like it will be to complex to fly.

Click to expand...

Hey Bill,

This was all done over a few day period. But, it is moving fast. I am especially looking forward to rigging the electronics.

For anybody who is interested, here is the Open Rocket File...

View attachment Purple Scratch - 2 stage.ork

There is one thing I don't understand... When I run a flight simulation, it seems to give me the performance from the Booster flight only. Is there something special you need to do to simulate a 2 stage flight?

csoechtig said:

Hey Bill,

This was all done over a few day period. But, it is moving fast. I am especially looking forward to rigging the electronics.

For anybody who is interested, here is the Open Rocket File...

View attachment 146170

There is one thing I don't understand... When I run a flight simulation, it seems to give me the performance from the Booster flight only. Is there something special you need to do to simulate a 2 stage flight?

Click to expand...

Change the ignition of the sustainer to 'First burnout of previous stage' plus your desired coast time.

Having flown my first and second 2-stage flights this past weekend, I highly recommend that you set your sustainer to fire upon burnout of the first stage. This will result in a "bang-bang" flight profile. I tried a 1.5 second staging delay on my first flight (G80 to F29), and I went for distance instead of altitude. On the second flight (H128W to F36SS), I eliminated the staging delay and staging was perfect! I didn't use a separation charge, but the resulting soot on the booster isn't too bad.

So, it's really two tips: Use a nice peppy motor in the booster, and light your sustainer upon burnout of the booster.

Polyalcoholic said:

Change the ignition of the sustainer to 'First burnout of previous stage' plus your desired coast time.

Click to expand...

Thanks.

patelldp said:

Having flown my first and second 2-stage flights this past weekend, I highly recommend that you set your sustainer to fire upon burnout of the first stage. This will result in a "bang-bang" flight profile. I tried a 1.5 second staging delay on my first flight (G80 to F29), and I went for distance instead of altitude. On the second flight (H128W to F36SS), I eliminated the staging delay and staging was perfect! I didn't use a separation charge, but the resulting soot on the booster isn't too bad.

So, it's really two tips: Use a nice peppy motor in the booster, and light your sustainer upon burnout of the booster.

Click to expand...

Thanks for the tips!

As far as a 'peppy' motor: I am going to decide which motors make the most sense once the build is done and I can weigh and balance the rocket. I was thinking the Booster Stage will be an 'I' impulse with an Average thrust in the 70-80 lbs. range

The second tip is really interesting to me - - virtually everybody else I've talked to suggests a separation charge for the booster. That said, I was planning a very short delay between the Boost and the second stage. I like the quick starts between stages.

Built the Motor Mount using 3 center rings. As you can see the aft center ring is off-set enough to allow room for the Booster Coupler to slide into place. Also, inserted the 1/4 Stainless Steel Tube and secured it in place with JB Weld. Finally, secured a 38mm Aeropack motor retention system with screw on cap (using JB Weld).



Attached a 20ft Kevlar shock cord to the forged eyebolt and tucked it into the mmt as I prepare to epoxy the whole set-up inside the Sustainer airframe.



Used Aeropoxy 6209 A/B to install the MMT...



And, began fin installation utilizing homemade fin jig... Considering the weight of the rocket and the width of the fins, I figured heavy duty internal filets were not necessary. In other words, if the rocket is subjected to a hard landing, this will not be the breaking point. So, I simply injected a heavy bead of AP 6209 onto the MMT tube through the fin slots. Eventually, I will add external filets using West Marine epoxy+filler.

I finished attaching all 3 fins to the Sustainer...



Here she is pieced together...



And here it is sitting on the Booster...



Next Steps:

1. Apply Fin Filets
2. Rig AV Bays

That is looking sweet Chris. Got good lines also.

Getmore said:

That is looking sweet Chris. Got good lines also.

Click to expand...

Thanks Bill - - It's a pretty straight forward design/build (other than the MMT). Once I test out the 38mm/38mm design, I might scratch build a 54mm booster with a slightly different configuration.

I'm concerned that I won't have my RRC3 Xtreme Altimeter in time for the 10/19 TTRA launch. Missile Works was hit hard by the CO flood and has not responded to e-mails or phone calls. If I don't have the RRC3, I might just test the booster flight and all the deployments. That will give me a better sense for what to expect and how to program the 2nd stage in November. Plus, I have a couple other cool flights planed for October (HyperLOC 1600 on an L900DM and Upscale Mean Machine on J180T). What about you?

Applied fin fillets using West marine epoxy w/filler...



and started setting up the Sustainer AV Bay...

I had a good launch last weekend flew my first K550 motor then two other rockets. For next month I have a K456dm and a couple I motors for two other rockets. Looking forward to next month.

My first HP two-stager is getting close to flight ready - -

I finished constructing the bulk plates for both AV bays... two charges per side (for redundancy) on the Sustainer and one charge per side for the Booster (one for separation and one to deploy the booster chutes). I also cut new sleds to maximize the space inside. I'll post pictures once I rig the electronics.

I applied wood filler to the fin fillets (purely cosmetic).



And, stripped the paint from the Booster. I always hated that purple color and will do something much cooler (tbd).



All I have left is minor rigging - - shear pins, removable rivets, reset one of the rail guides, electronics, etc.

I did hear back from Missile Works. They are still recovering from the floods in CO and will be processing orders over the next couple weeks. I really feel for those guys and am not concerned about getting my RRC3 in time for the October 17th launch. In fact, I've already decided to 'test fly' the booster before attempting my first air start.

I plan to use an Aerotech I284W (38/600 - total impulse of 607Ns). The rocket stands exactly 7.5 ft tall and will weigh about 8 pounds on the pad. I expect about 2,200 ft for the test. Hopefully, I'll be able to see the separation charge and get a sense for what direction the sustainer is facing when the second stage is set to ignite (in November).

qquake2k said:

Great build, Chris! I really need to get into HP staging. I've really wanted to build an upscale Estes Omega for a long time.

Click to expand...

Thanks Jim - - This has been a pretty fun build. I'm looking forward to gaining some confidence with air-starts so I can explore some cool up-scale projects as well. I think mine might be an Estes Express.

Woo Hoo - - Missile Works is back in business!!!

And so are you:wink:

I started rigging the Sustainer electronics last night. Setting up redundancy in a 3" AV bay always requires a little creativity. Here's how I went about it...

The Altimeters will are mounted on opposite sides of the sled (both using Perfect Flight mounting hardware). The mounts are off-set so that only 2 of the nuts from the SL100 will be beneath the RRC3. Also, I used 2 small washers to ensure the screws did not make contact with the underside of the RRC3.



Here is the RC33 on the top of the sled...



And the SL100 mounted between the sled's mount lugs.



Both batteries sit flush against the drogue-side bulk plate. Small wood blocks are used as 'stoppers' and a zip-tie is used secure both batteries (back to back). One of the drogue wires runs up the side of the sled and is secured to the Altimeter. Another wire is screwed into the Aux output and is run along the same side of the sled. This wire runs out a newly drilled hole in the Bulk Plate and will be used to rig the Air-start. Both wires are secured to the sled using small zip ties...



It's a similar set up for the SL100. I did not secure the Drogue wire yet as it will be used for ground testing.

Now, it's time for venturing into new territory - - As stated earlier in the thread, I will be running the Air-start wire out of the Sustainer AB bay and down through a 1/4" SS tube. If all goes as planned, the Sustainer should ignite before drogue separation. Once the Sustainer reaches apogee, the drogue will separate. So, I needed a way for the air-start wires to disconnect upon that separation.

My original plan was to use some sort of R/C plug. Unfortunately, I couldn't find exactly what I was looking for and decided to use crimp-type wire connectors. I was able to manipulate the crimps so the male-end easily slides in and snugly locks in place. With a quick tug, they release without a problem. All were soldered in place...





I figured I will want some protection between the two leads so they do not touch each other and potentially short out. I'll probably feed a couple disposable pieces of rubber tube around the wires before launch...



I really like the safety benefits behind this configuration. If for some reason the sustainer does not ignite, the continuity wire will be disconnected at apogee. That being said, I am sure there are better ways to set-up release clips and would be really interested in feedback from others who have done this.

csoechtig said:

...and would be really interested to get some feedback from others who have done this.

Click to expand...

I've always just used breakwires for this connection, as shown in the pic. I use a couple extra feet of wire so that there's nothing that prevents the parts from separating at a minimum. These take a gook yank to separate, so both ends of the wire need to be firmly secured.

Jim

Your setup looks good. I wonder if banana clips would be better.But I guess it will disconnect with the force of the bp no matter what you have for the connection to disconnect.

JimJarvis50 said:

I've always just used breakwires for this connection, as shown in the pic. I use a couple extra feet of wire so that there's nothing that prevents the parts from separating at a minimum. These take a gook yank to separate, so both ends of the wire need to be firmly secured.

Jim

Click to expand...

I saw Jim mention this method somewhere else on TRF, I used it in my Quantum Leap and it works great.

JimJarvis50 said:

I've always just used breakwires for this connection, as shown in the pic. I use a couple extra feet of wire so that there's nothing that prevents the parts from separating at a minimum. These take a gook yank to separate, so both ends of the wire need to be firmly secured.

Jim

Click to expand...

Makes perfect sense - - I'll see how my connection works. If I experience problems, I'll simply go with the twist, tape, tuck method. Thanks for sharing.

Ground tested the rocket last weekend (4 different events)...

Separation of Booster from Sustainer (I believe .5 grams might be a bit too much BP)...
[video=youtube;Ib3JwQYfJz8]https://www.youtube.com/watch?v=Ib3JwQYfJz8[/video]

Booster Chute Deployment (.75 grams look good)...
[video=youtube;Noin2HLmnYo]https://www.youtube.com/watch?v=Noin2HLmnYo[/video]

[video=youtube;avXa05gzDtc]https://www.youtube.com/watch?v=avXa05gzDtc&feature=c4-overview&list=UUlpeO6TkqR9AA-tYQbieDXw[/video]

Sustainer Main Chute Deployment (.75 grams look good)...
[video=youtube;pFosHaR6UeI]https://www.youtube.com/watch?v=pFosHaR6UeI[/video]

I also primed the rocket...


Unfortunately, I was on the road this whole week and will not have it ready for the test launch this Saturday. It looks like I will wait until November.

csoechtig said:

Separation of Booster from Sustainer (I believe .5 grams might be a bit too much BP.

Click to expand...

I use 0.3 grams for a 4". Build looks good!

Jim