Advice: LOC Terrier/Sandhawk Build

[Budro0]

Hi all. I've wanted to build a HPR two stage for a while. I picked up a LOC Sandhawk and Terrier booster a while back and I think it might make a good winter project for me this year. I have lots of questions though. I have tried searching the forums and haven't really settled on how I'm going to approach the staging and deployments.

I watched all the Apogee videos on this kit, but I don't like the idea of cutting a hatch in a 2.1" tube for electronics. Has anyone ever tried to cut the lower portion of the Sandhawk and add a second coupler with electronics right above the motor mount? It would remove any motor eject back up but I think with a stiffy coupler and screws, it should be pretty robust.

My other idea was just to run long wires which are loosely spliced up to the Proton in the ebay for separation and air start. It seems like this is a more common method and allows the wires to break free at the apogee deployment. And it will be overall lighter...

Thoughts?

 

[NTP2]

I would trust apogee Tim knows what he is doing.

 

[markg]

My other idea was just to run long wires which are loosely spliced up to the Proton in the ebay for separation and air start. It seems like this is a more common method and allows the wires to break free at the apogee deployment. And it will be overall lighter...

Either way would work, it's kind of up to you to decide which you'd prefer. Personally I prefer a tranditional ebay, so I'd go with your second option, running a long wire up to the ebay. If you twist/tape the wire and wrap it around the eyebolt on the ebay the wire will easily separate when the rocket does.

cheers - mark

 

[Budro0]

I would trust apogee Tim knows what he is doing.

I do too. But then I'd have to trust me to make that hatch cut in the tube...

 

[NTP2]

I do too. But then I'd have to trust me to make that hatch cut in the tube...

I would make a jig with cardboard.

 

[Rocketclar]

Here's my stretched LOC Terrier/Sandhawk with me (at 6') at NSL-E. It's flown a number of times, successfully on I's to G's or H's. I don't use motor eject for either stage. Booster comes apart at its lower black/orange section. I have an ebay in that part that contains a MW RRC2+ with an Eggtimer Apogee as a backup charge. For both stages I use JLCR's for the parachutes.
I added sections....like in the sustainer for an Eggfinder GPS sled near the NC. The Proton is in an ebay at the lower orange/black section. I also have an Eggtimer Telemetry module next to the Proton. Comes apart at the break between the upper black section with the middle orange. I run wires down to the motor thru a small cardboard tube. I never was able to get drag separation so I use a small sep charge by packing BP around a Firewire and taping it up. When I hook up the sustainer motor, I just wire wrap then tape over to prevent shorts. I also have a video camera pointing down on the sustainer near its motor. I have tried adding another camera pointing up, but saw mostly a washed out sky so gave that up. I have posted some pictures and video from past flights. I did paint the inside of the ISC with high temp paint and stuff it with dog barf and wadding. That was important since I didn't get drag sep with separation coming from sustainer ignition. Since I've used a sep charge, not needed as the booster clearly separates as seen in my video or pictures.
Good luck. I found the challenge very fulfilling.
BTW....I, too, bought one of Apogee's ebay sleds where you had to cut into the AF. Decided not to do it. My setup did require me to cut out several bulkheads so I could fix to the AF to hold ebay and GPS sleds in place.

 

[Rocketclar]

Oh, I replaced the LOC thin sustainer nylon shock cord with Kelvar since it burned thru on one flight.

 

[Budro0]

Here's my stretched LOC Terrier/Sandhawk with me (at 6') at NSL-E. It's flown a number of times, successfully on I's to G's or H's. I don't use motor eject for either stage. Booster comes apart at its lower black/orange section. I have an ebay in that part that contains a MW RRC2+ with an Eggtimer Apogee as a backup charge. For both stages I use JLCR's for the parachutes.
I added sections....like in the sustainer for an Eggfinder GPS sled near the NC. The Proton is in an ebay at the lower orange/black section. I also have an Eggtimer Telemetry module next to the Proton. Comes apart at the break between the upper black section with the middle orange. I run wires down to the motor thru a small cardboard tube. I never was able to get drag separation so I use a small sep charge by packing BP around a Firewire and taping it up. When I hook up the sustainer motor, I just wire wrap then tape over to prevent shorts. I also have a video camera pointing down on the sustainer near its motor. I have tried adding another camera pointing up, but saw mostly a washed out sky so gave that up. I have posted some pictures and video from past flights. I did paint the inside of the ISC with high temp paint and stuff it with dog barf and wadding. That was important since I didn't get drag sep with separation coming from sustainer ignition. Since I've used a sep charge, not needed as the booster clearly separates as seen in my video or pictures.
Good luck. I found the challenge very fulfilling.
BTW....I, too, bought one of Apogee's ebay sleds where you had to cut into the AF. Decided not to do it. My setup did require me to cut out several bulkheads so I could fix to the AF to hold ebay and GPS sleds in place.

This is great info, but I want to make sure I'm reading it all correctly. Your sustainer has essentially four sections: nosecone, two sections of airframe, and the fincan. Then you run airstart and separation events from the fincan ebay, and parachute deployment from an ebay in the upper airframe break. If so, that is almost exactly what I'd like to do. What do you do for motor retention on the sustainer? Friction-fit? It seems like if you have an empty bulkhead right above the MMT, you could install a bolt like a min diameter retainer...

 

[Rocketclar]

I use a Mad Cow motor retainer for the booster and friction fit the sustainer motor casing. I use CTI motor for the sustainer since they have the pellets and light easily with a Firewire. I've used both AT and CTI boosters.
Here's a breakdown of each section. I used my circle cutter on my drill press to cut 1/2 and 3/4" plywood for various bulkheads. I then attach those to the AF with screws. The dowel on the GPS sled is so I can turn it to match the holes for the screw switch and securing screws. I shear pin that module. Since cardboard, I use brass shims on the inside of the AF to help cut the pins. That's worked well for me with a number of my cardboard rockets. I also shear pin the booster ebay to fin can. I coated the coupler with a light epoxy for strength. You can see my 4 caps for holding the BP charge cannisters. I seal wires going thru bulkheads with hot glue.

 

[Budro0]

I use a Mad Cow motor retainer for the booster and friction fit the sustainer motor casing. I use CTI motor for the sustainer since they have the pellets and light easily with a Firewire. I've used both AT and CTI boosters.
Here's a breakdown of each section. I used my circle cutter on my drill press to cut 1/2 and 3/4" plywood for various bulkheads. I then attach those to the AF with screws. The dowel on the GPS sled is so I can turn it to match the holes for the screw switch and securing screws. I shear pin that module. Since cardboard, I use brass shims on the inside of the AF to help cut the pins. That's worked well for me with a number of my cardboard rockets. I also shear pin the booster ebay to fin can. I coated the coupler with a light epoxy for strength. You can see my 4 caps for holding the BP charge cannisters. I seal wires going thru bulkheads with hot glue.

That's excellent information and pictures. I really do appreciate the detailed rundown. I do think I'm going to follow in your footsteps and cut down the sustainer - although I am thinking I'll have one less cut than you. I had already settled on adding an ebay to the booster, so I appreciate the confirmation there.

Another question for you (or anyone) - did you add rail button standoffs for the sustainer? Or does it not attach to the rail in the 2 stage configuration?

 

[Titan II]

My other idea was just to run long wires which are loosely spliced up to the Proton in the ebay for separation and air start. It seems like this is a more common method and allows the wires to break free at the apogee deployment. And it will be overall lighter...

Thoughts?

This way is the ticket.

 

[NTP2]

Another question for you (or anyone) - did you add rail button standoffs for the sustainer? Or does it not attach to the rail in the 2 stage configuration?

It seems to me that that would make so much drag that you would be sky writing.

 

[Titan II]

It seems to me that that would make so much drag that you would be sky writing.

You can't be serious.

 

[NTP2]

You can't be serious.

Look at it the top stage looks an inch thiner so the stand of is an inch right or is it less and I am miss judged the distance.

 

[markg]

Another question for you (or anyone) - did you add rail button standoffs for the sustainer? Or does it not attach to the rail in the 2 stage configuration?

Sustainer does not attach to the rail in 2 stage configuration. You can add rail buttons if you want to fly it stand-alone, otherwise don't bother.

cheers - mark

 

[Rocketclar]

Another question for you (or anyone) - did you add rail button standoffs for the sustainer? Or does it not attach to the rail in the 2 stage configuration?

No, I didn't add rail buttons to sustainer as I never planned to fly it by itself. There is an offset due to the different diameters as folks above have indicated.

 

[Cameron Anderson]

I added a Loc av bay to my Sandhawk and trimmed the top off my Terrier to make an an-hoc av bay that I attached to the ISC so I could fly electronics in both sections, fly like a dream