Packing issues-semi long

[Gregor]

I'm finishing up my first mid>>high power rocket that I hope to certify with later this fall. It is a Loc Phantom. It has many of the standard upgrades and is likely to weigh a little over 3 pounds when finished. I went for a Pinnacle 5 to 1 ogive nose cone to replace the one that came with the rocket. I love the look of this rocket with that new nose cone. The problem is that the part of the cone that goes into the tube is several inches longer than the stock cone, and when I pack everything and stuff it in the tube, the cone barely fits onto the tube. I actually have to push down on all the laundry to get the cone in freely. Is this a problem? If I had to I could cut the cone and mount a bulk plate but I really don't want to do that if I don't have to. Also I hope to test this with a G motor and was wondering if the ejection charge would be sufficient to pop off the nose cone and all that laundry. Sorry for the long post and thanks for any responses.

 

[ben]

well, you could cut the nosecone. That would give you 4-6" more of space. That is what i would do personally. You could try and pack it tight(er) and hope it comes out

Ben

 

[smurf]

Two words - Shear Pins

I've had plenty of rockets that have "space issues". Talk to anyone that likes to fly minimum diameter rockets and they can tell you all about the gyrations to get everything in a rocket.

I have a 4" raptor that the nosecone will not stay seated by itself. I solved the problem by putting in three 2-56 x 1/2" shear pins. Basically push the nose cone down, put in the shear pins and it's perfect every time. Use any of the shear pin calculators for your initial charge and then ground test.

Piece of cake. I don't fly without them anymore.

 

[Art Upton]

After the shear pins,

add extra black powder to the ejection charge of the "G" motor to snap the pins. Many ways to do this depending on the exact motor style.

I tend to be on the blow it out or blow it up side of the fence on recovery charges.

 

[Gregor]

I'll probably test the rocket on a G64 or G71 reload. Where do you get the black powder and how would you figure out how much to add? I don't have a scale so I hope there is a way to eyeball it.

 

[als57]

I'll probably test the rocket on a G64 or G71 reload. Where do you get the black powder and how would you figure out how much to add? I don't have a scale so I hope there is a way to eyeball it.

With the Hobby line the max is what will fit in the little red snap cap. Never weighed it ; but I'm guessing 1.5gr or less. A fair ammount more will fit in the well of a 29 or 38mm HPR closure.

Al

 

[Sandy H.]

I am new to considering shear pins as I plan to try DD in the near future. I have read about adding some thin CA to strengthen the areas for the shear pins etc, so I feel that I have many of the basics under control.

As far as ground testing goes, though, what do the non-LEUP's typically do? I guess I could prep a charge at the field, take it to the flight line and ask the LSO to eject it for me using an igniter, but that only gives me a small window to test, then fly the rocket later. What do you guys suggest?

Also, since you are suggesting using the shear pins for holding the nosecone in place on a motor deploy rocket in this case, do those of you who use shear pins for DD also typically fly them on all of your MPR/HPR rockets because of the repeatability or do you only typically reserve them for DD birds? I like the idea of consistency and not needing to tape the nosecone shoulder to friction fit the nosecone (which would be another option for the original poster, correct) but I also like to be able to fly rockets 20+ flights and have not convinced myself that 2-56 nylon screws won't eventually rip up the body tube.

Thanks for the help. Hope this is only a minor thread deviation, not a hi-jack!

Sandy.

 

[Art Upton]

Answers to a few of the questions:

Ask your rocket clubs buddies for some extra Black Powder, someone their should have some. If using shear pins in a motor deploy rocket to hold the long cone on, put as much power as that hobby line engine will hold.

1.5 or so grams should fire two 2-56 plastic screws.

if using shear pins on Duel Deploy I use two 2-56 screws on 4" loc tubes by drilling into the tube and nose cone at the same time, putting the screw in and holding it in with some masking tape across it and the tube; as my holes and the screws are the same size, they don't screw on.

I've not used any hole stiffing yet on any of my LOC paper or my fiberglass tubes. The 2-56 plastic screws shear off fine for me, your milage may vary.

Shear pins on Single deploy rockets;I sure wish I did it on my FiberGlass Nike Smoke at LDRS 25.

The nose cone seperated due to drag/weight differances at MECO and she zipped on the way up :surprised: