Placement of drouge chute

[John Taylor]

I have a 14lb on pad, 4" diameter, 8' tall DD rocket where the aft section contains the drouge and the forward section has the main popping off the nose cone.
The aft section is heavier than the top section. My shock cords are 20' each.
I want the forward section with the main to be above the aft section while falling so the main will deploy without tangling with the aft section.
Ok so far?
Where on the aft section shock cord should the drouge chute attachment point be?
I'm thinking towards the top section of the shock cord, about 5' from the mid airframe section, away from the heavier aft section.
Does that sound best?
Thanks!

 

[rharshberger]

I have a 14lb on pad, 4" diameter, 8' tall DD rocket where the aft section contains the drouge and the forward section has the main popping off the nose cone.
The aft section is heavier than the top section. My shock cords are 20' each.
I want the forward section with the main to be above the aft section while falling so the main will deploy without tangling with the aft section.
Ok so far?
Where on the aft section shock cord should the drouge chute attachment point be?
I'm thinking towards the top section of the shock cord, about 5' from the mid airframe section, away from the heavier aft section.
Does that sound best?
Thanks!

Thats a good location, or iirc OneBadHawk recommends between 1/4 and 1/3 the length of the harness so a drogue would be attached between 5' and 6.5' from the Altimeter bay in a normal mid break DD rocket (hopefully I am remembering my conversations with Teddy correctly).

 

[John Taylor]

Thats a good location, or iirc OneBadHawk recommends between 1/4 and 1/3 the length of the harness so a drogue would be attached between 5' and 6.5' from the Altimeter bay in a normal mid break DD rocket (hopefully I am remembering my conversations with Teddy correctly).

Thank you

 

[Rocketclar]

I've always used what one of my PML kits recommended......attach main about 1/3 from NC and attach drogue about 1/3 of the way from fin can. Folding up the SC in thirds makes finding the attach points easy. I also lay out everything in the basement to see if anything is going to hit and tweak if I have to.

 

[Bat-mite]

I have a 14lb on pad, 4" diameter, 8' tall DD rocket where the aft section contains the drouge and the forward section has the main popping off the nose cone.
The aft section is heavier than the top section. My shock cords are 20' each.
I want the forward section with the main to be above the aft section while falling so the main will deploy without tangling with the aft section.
Ok so far?
Where on the aft section shock cord should the drouge chute attachment point be?
I'm thinking towards the top section of the shock cord, about 5' from the mid airframe section, away from the heavier aft section.
Does that sound best?
Thanks!

That's pretty much what I do.

 

[UhClem]

You have two conflicting requirements at drogue deployment that you need to balance.

For best drogue deployment it should be attached as close to the fin section as possible to prevent that section from hitting the drogue. See Ted Cochran's NARAM 42 R&D report.

For best main deployment the drogue should be placed so that the main parachute bay is not below the fin section.

Obviously you can't do both at the same time. I have decided that my primary requirement is getting a good drogue deployment so that if nothing else happens, the rocket comes down in a controlled manner on the drogue. So the drogue gets placed at the fin section which works well with my typical anti-zipper design. YMMV

Example