Parachute placement

I'm building a Thor 4 DD. My drouge cord is 25 ft. long and my main cord is 15 ft. long. Where is the best placement (inches from cone and inches from e-bay) to tie the chutes ? Drouge is 18 in. and the main is 38 in.

I usually put the drogue about 4-5 ft. from the ebay attachment. Generally about the same for the main. About 3-4 ft. from the NC attachement.

As a side note, I would suggest a longer shock cord for your main. 15ft. is probably minimum for this size rocket. I would go 20-25 ft. if you can. While you can go "too long", I like to have plenty of cord to minimize ejection forces when the cord draws tight. Just my unsolicited $.02

cobra1336 said:

I'm building a Thor 4 DD. ... and the main is 38 in.

Click to expand...

If your THOR ends up weighing anything like mine, that 38in main is
going to be waaay too small. Be sure and check your final weight
(including expended motor casing)! Adjust for field conditions
as necessary.

My Valkyrie 3 scratch is 130 oz without motor,
has 30" drogue and a 60" main chutes and still comes down
with a bit of a thunk...

Layout is nosecone - 1/3 length tk - main - 2/3 length tk - avbay -
1/3 length tk - drogue - 2/3 length tk recovery cord - booster section...

Seems to work...

Kit states that the main is a 45" but by measuring it across it's widest part I get 38. Am I measuring wrong? I'll buy another cord.

I can't answwer the question...I just want to know about that Cobra in the Avataar....

I always put my drogues and mains relatively close to the seperation points. The reason being is that I want to make sure the chutes come out, so I usually go no farther than a foot or two back. For the drogue, this allows the sustainer to fall away from the avionics bay and drag the chute out. For the main, it allows the nose cone to drag it out.

Most 40 to 45in are good for approximately 4-9 lbs rockets giving you a 15 to 25ft per second descent rate. I use a 60 in, on my Thor, as it weighs 6 1/2 lbs ready for the pad, without motor. The 60 in is good for 7-12 lbs and 15 to 20ft per second descent rate, depending on flight weight.
Depending on what I am flying the hardware will add an extra 1lbs to 3.
Also the terrain you fly on will make a difference. Fields or sod are much more forgiving than Playa or hardpack. You must figure in these things ,when determining what size chute. I also use a longer shock cord, [25ft on both] and tie them off just a few ft from the payload and nose,and shear pins on the nose.

I have yet to figure out how some chutes are measured, but yes the supplied chute from BSD is a 45 and will work fine if you built light. I put a glass sock on mine. Weighing yours is the only way to be sure.

All good advice. I'll get the longer cord and weigh it tomorrow.
MaxQ it's mine, Factory Five Racing Mk I. I've had it for 3 years. Built and installed a gt 40 motor for it 2 years ago.

Rough weight looks like 7 lbs.