Bounty Hunter needing nose weight?

[4regt4]

Just curious if anyone else found the need to add nose weight to a North Coast Bounty Hunter. Went to a launch event this weekend for the maiden voyage of my B.H., only to find it was tail heavy with an F67-6W SU. Found some 1/4" quick links (about 1 oz.) to put in the top of the payload bay with a lot of tape to put it right at 1 caliber stability.

Built it with RocketPoxy, but didn't get carried away with quantity. Did rather small-ish fin filets also.

Had a PNut altimeter attached to the nose cone. The nose cone base was wrapped with tape until it was a very tight fit. Hard to pull it off because of difficulty getting a grip on the slick paint. But the cone separated on ejection, almost lost it. So now I'm reluctant to try and weigh down the cone unless I find a more secure way to attach it. Maybe plastic rivets?

Hans.

 

[Rob Campbell]

Do you have a bulkhead between the booster tube and the payload tube?

 

[4regt4]

Do you have a bulkhead between the booster tube and the payload tube?

Yes, the shock cord is tied to that bulkhead. The payload tube has vent holes for the altimeter. I'm surprised that North Coast's instructions didn't mention this would be needed.

Hans.

 

[Rob Campbell]

Your nose cone shouldn't be separating at ejection. The bulkhead should keep the ejection gasses out of the payload tube and the vent holes should equalize pressure during ascent.

 

[lakeroadster]

Your nose cone shouldn't be separating at ejection. The bulkhead should keep the ejection gasses out of the payload tube and the vent holes should equalize pressure during ascent.

It separates due to the momentum of the nose cone (and ballast in the nose cone) being suddenly stopped by the shock chord, not due to the ejection charge.

 

[4regt4]

It separates due to the momentum of the nose cone (and ballast in the nose cone) being suddenly stopped by the shock chord, not due to the ejection charge.

At least that's what I'm assuming. And it'll be worse next time out, as I have to add more ballast.

At this point, I'm hoping longer shock cord and plastic rivets will do. Fingers crossed.

Hans.

 

[Tractionengines]

LONGER SHOCK CORD... (no elastic you don't want that much mass springing back...)

 

[waltr]

^^this and then Braid the cord to absorb energy to slow the nose down so it does not Snap to a stop.

 

[bjphoenix]

Your nose cone shouldn't be separating at ejection. The bulkhead should keep the ejection gasses out of the payload tube and the vent holes should equalize pressure during ascent.

I still have a very old Estes XRay, I believe back in those days we would push straight pins in through the clear payload tube to keep the nose cone in place. For my LOC kits I have put small sheet metal screws through the side of the payload tube into the nose cone.

 

[4regt4]

^^this and then Braid the cord to absorb energy to slow the nose down so it does not Snap to a stop.

Actually, I sort of zig-zag the Kevlar and use masking tape to secure the loops. Apparently the force of ejection is violent enough that on landing there isn't a trace of that tape....

Hans.

 

[waltr]

^^ That also works well to absorb energy.

 

[gdjsky01]

There are very cheap removable plastic rivets on eBay that will keep a NC on. Only downside is it takes about two weeks from China to get them.

 

[Donnager]

There are very cheap removable plastic rivets on eBay that will keep a NC on. Only downside is it takes about two weeks from China to get them.

In stock for overnight delivery from McMaster Carr, also, but the price may be higher (~$14-15 for 50 plus UPS).

 

[4regt4]

I got mine from Chris Rocket Supplies. csrocketry.com No need to wait for a shipment from China.

Hans.

 

[gdjsky01]

Yeah but mine were like $3 for 50