Single chute DD with cutter -- sanity check.

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Bat-mite

Bat-mite

Rocketeer in MD
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To anyone who has done DD with a single chute and a cable cutter,

Perhaps you can help me with a sanity check on what I am planning, before I spend my hard-earned money.

I have an Estes Leviathan built for HPR. On a small H, it's going way up there. My choices? Put a tracker in it and take the recovery walk; or, do dual deployment and try to land it closer to the pad.

I thought about going with an Archetype Cable Cutter and Adept DDC22 altimeter. Not a bad solution for $60.00.

To do this, I will need to put the altimeter in the nose cone. And as I was considering how I would do this, a question came to mind that I hadn't thought of before.

How do you put sensor holes in a nose cone? Do you just drill into the sides of the ogive? Do you drill through the airframe and into the shoulder (but then how do you keep them lined up)?

Also, in terms of a switch, I am thinking that since the BP explosion that causes the cable-cutting is contained inside the cylinder, then there is no risk of injury if the charge goes off early, and as such, there is no need for an altimeter switch. Activate the altimeter before or after the RSO inspection by attaching the battery, and leave it armed. Anyone see an issue with that?

I was thinking motor ejection, and us the altimeter to cut the cable.

Things I need:
  • Cable Cutter Kit
  • Altimeter
  • Sled, inner and outer bulkheads for nose cone
  • Wood glue
  • Nomex
  • Igniter/starter/e-match
  • BP
  • Terminal block

In summary:

  1. Where do the vent holes go in the nose cone?
  2. Can I go switch-free?
  3. Am I missing anything in my list of parts?
  4. Any other ideas/warnings/thoughts?

Thanks!
 
Bat-mite said:
To anyone who has done DD with a single chute and a cable cutter,

Perhaps you can help me with a sanity check on what I am planning, before I spend my hard-earned money.

I have an Estes Leviathan built for HPR. On a small H, it's going way up there. My choices? Put a tracker in it and take the recovery walk; or, do dual deployment and try to land it closer to the pad.

I thought about going with an Archetype Cable Cutter and Adept DDC22 altimeter. Not a bad solution for $60.00.

To do this, I will need to put the altimeter in the nose cone. And as I was considering how I would do this, a question came to mind that I hadn't thought of before.

How do you put sensor holes in a nose cone? Do you just drill into the sides of the ogive? Do you drill through the airframe and into the shoulder (but then how do you keep them lined up)?

Also, in terms of a switch, I am thinking that since the BP explosion that causes the cable-cutting is contained inside the cylinder, then there is no risk of injury if the charge goes off early, and as such, there is no need for an altimeter switch. Activate the altimeter before or after the RSO inspection by attaching the battery, and leave it armed. Anyone see an issue with that?

I was thinking motor ejection, and us the altimeter to cut the cable.

Things I need:
  • Cable Cutter Kit
  • Altimeter
  • Sled, inner and outer bulkheads for nose cone
  • Wood glue
  • Nomex
  • Igniter/starter/e-match
  • BP
  • Terminal block

In summary:

  1. Where do the vent holes go in the nose cone?
  2. Can I go switch-free?
  3. Am I missing anything in my list of parts?
  4. Any other ideas/warnings/thoughts?

Thanks!
Click to expand...

This all can be done. My comments on your questions...

1) I have always had success with a hole right at the base of the nosecone (above airframe seam).
2) I wouldn't. Even if you did twist and tuck you would be better off than trying to arm and button up the alt on the pad.
3) On your list I see wood glue but no other adhesive. Assuming your nosecone is plastic you are going to need epoxy and maybe even some mechanical attachment in the nose to be safe for mounting of sled, bulkhead, chute attach, etc.
4) The biggest problem with tethers and cable cutters is tangling during descent. Properly dressing and prep'ing all wires and shock cord sections is critical to success.
 
Just realized I can't do this with the stock nose cone. The bottom of it slopes/narrows to make room for the place where the chute/shock cord attach.

levNC.JPG

Can anyone suggest an after market nose cone that will fit the Leviathan?
 
Bat-mite said:
Just realized I can't do this with the stock nose cone. The bottom of it slopes/narrows to make room for the place where the chute/shock cord attach.
Click to expand...

your nose cone is not a problem at all, I mod a G-Force and a Arreaux one and they have the same form

nose2.jpgareaus.jpg
 

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Please do not arm HPR rocket anywhere other than launch pad. Perhaps your design is safe but others may not be aware of it and not feel safe. And then, depending on volume and how tight the laundry is packed, even a small charge may be enough to set things in motion.

Not to be negative, everything else makes sense! Get a tracker or at least a beeper...


-Alex
 
A standard dual deployment setup only requires the Adept22. I'm afraid I don't see the need or justification for the cable cutter.

IIRC the Leviathan used a 2 piece airframe joined with a coupler and a NC. You can put your altimeter inside the coupler if you make two bulkheads for the coupler.

At apogee you can use either motor ejection or the Adept 22 apogee charge to separate the rocket at the fin can joint for a fast drogueless descent until you deploy the main with the Adept22 barometric charge by popping the NC off. This total avoids the weight, complexity and expense of the cable cutter all together.

Bob
 
Here is an option if you don't mind stretching your Leviathan a few inches. Make an AV bay, add a very short piece of body and then the nose cone. I made this set up to use on an existing rocket with a cable cutter.

Photo Aug 12, 4 39 46 PM.jpg

I went this route instead of making nose cone mods because I can switch back and fly the rocket without DD. I also built a Leviathan and modified as suggest in one the post above. A 6" long tube coupler was long enough to make an AV bay.
 
Thanks, all.

I neglected to mention that the rocket is already built and painted and has been flying on G impulse. But I know it can handle an H, and I want to try it. So I see the cable cutter as a way of doing DD with one separation point and one parachute.

On Saturday, I am going to fly it on a 164H90-12A, single deploy. BRB900 will be in the nose. I'll see how high it gets and how far away it comes down.

I have also ordered a second Leviathan nose cone and coupler. I hope to cut off the nose cone shoulder completely and use the coupler as a nose cone extension with the electronics inside. I hope to make the sled, bulkheads and CR out of wood so that there is nothing to interfere with the GPS transmission
 
bill2654 said:
I also have an Arreaux with a Adept 22 in the nose cone with cable cutter for chute deployment. It's really tight but it can be done.
Click to expand...

I need length to accommodate my tracker antenna or a TeleMetrum
 

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