Quantcast

Upcoming Level 1 Attempt - and Geaux Tigers!!!

The Rocketry Forum

Help Support The Rocketry Forum:

Murrill

Well-Known Member
Joined
Dec 15, 2010
Messages
46
Reaction score
0
Geaux Tigers!!!
LSU National Champions!!!

Okay, now that I got that out of my system, I will be attempting my Level 1 certification at High Cotton XVII, the Louisiana Tripoli state-wide launch on January 17-18. I probably would not have posted anything about the attempt until after the launch was over (successful or otherwise), but I owe a huge thanks to several people and wanted to go ahead and express my gratitude to these folks.

First, Carl Tulanko (make that Tulankeaux) patiently and in great detail answered a plethora of e-mails I sent him regarding fiberglass techniques. I owe him a tremendous "thanks" for all of his help.:)

Second, Ed Shihadeh at Giant Leap Rocketry helped me obtain the motor for the attempt (a Pro38 I-205) and also gave me a lot of good tips about building the rocket. Ed lives just a mile or two from me, it's nice to have such a great resource so close to home.:)

Third, Bob Mosher is the Tripoli prefect for the Louisiana club and has helped me coordinate the attempt and all of the associated administrative hurdles. Bob also gave me lots of good tips about building the rocket.:)

Anyway, on to the rocket. I'm buildng a 1/4 scale PML Patriot, the rocket is four inches in diameter and takes a 38mm motor. After reviewing the many helpful replies I received to queries on this forum, and after lots of e-mails back and forth with Carl, I decided against glassing the tube, but did fiberglass the fin can. At Carl's suggestion, I cut sections of glass that laid on the tube between the fins and extended one or two inches up the side of each adjoining fin. I used West Systems expoxy; after it was dry, I sanded the glassed areas to blend them into the fins and body tube as much as possible. This was my first attempt at glassing, it was easier than I thought, but it did require a lot of sanding to smooth out the areas (and I don't think I will ever get them as absolutely smooth as I would prefer).

After glassing and sanding the fin can, I applied external fillets, as well as internal fillets where the TTW fins attach to the motor mount. All surfaces that were epoxied - the fins, the tube, the motor mount - were scuffed with sandpaper prior to gluing.

Tonight's project will be to apply expanding foam to the inside of the fin can, then glue in the rear centering ring.

Motor retention will be with a PML device.

At the suggestion of Bob Mosher and Ed Shihadeh, I am not going to use the PML piston system. I have successfully flown a PML Amraam several times using G class motors and have never had any problems with the piston system. However, Bob and Ed both recommended that I forego the piston on the Patriot, and I am taking their advice. I will use a Kevlar chute protector to replace the piston.

The nose cone on the rocket is attached semi-permanently to a forward section of body tube. (Recovery separation occurs between the two sections of body tube). The nose cone may be attached by sheet metal screws or by PML removable rivets. If anyone has shown the endurance to read this far in the post, do you have any recommendations as to whether to use the screws or the rivets?

Also, is it really necessary to drill a pressure relief hole in this rocket?

Once the rear centering is in place, the actual construction will be nearly complete, and it will be time to prime and paint. I'll try to post a pic of the completed rocket prior to the launch.

Anyway, thanks again to Carl, Ed, Bob, and everyone who posted replies to my queries here at the Rocketry Forum.

John Murrill
 

LMazza

Well-Known Member
Joined
Nov 14, 2003
Messages
131
Reaction score
0
Originally posted by murrill

If anyone has shown the endurance to read this far in the post, do you have any recommendations as to whether to use the screws or the rivets?

Also, is it really necessary to drill a pressure relief hole in this rocket?
For my Level 1 rocket which flew just this last October I ran across the same things as you. First, for nose cone attachment I used machine screws with nuts epoxied inside the nosecone. To do this it was neccesary to cut holes in the nosecone shoulder to get the nuts epoxied inside. I did it this way because it was much easier to just run to the hardware store and purchase these items.(They didn't have anything resembling plastic rivets.)

Second, once I arrived at the launch I was told that I should drill a pressure relief hole. It isn't hard and it's a good way of insuring that you won't have an early ejection.

Good luck with the launch! It sounds like you have built your rocket very well.:)
 

lalligood

Well-Known Member
Joined
Jan 21, 2009
Messages
1,985
Reaction score
0
FWIW, I used the rivets included with my BSD Thor when I built it. I like the rivets because they can be easily removed if you ever decide that you want to carry a payload. They pop out with a strong fingernail, slim screwdriver tip, or a knife blade but when they are fully inserted, there is little to cause them to (unwantedly) come loose!

And yes, it takes little effort to add the pressure relief hole. What's the old cliche...oh yeah, "an ounce of prevention is better than a failed cert attempt". Yeah, that's it :D

Good luck with the cert attempt & take pictures!
 

daveyfire

Piled Higher and Deeper
TRF Lifetime Supporter
Joined
Jan 26, 2009
Messages
3,218
Reaction score
54
Location
thank u, next
Originally posted by murrill
Geaux Tigers!!!
LSU National Champions!!!
Just because of a stupid BCS computer system that seems to have caused more harm and controversy than good...

TROJANS FOREVER... THE REAL NATIONAL CHAMPIONS :D :kill:

and don't even get me started on this subject ;)


Oh yeah... good luck on your L1!
 

havoc821

Well-Known Member
Joined
Feb 3, 2003
Messages
508
Reaction score
0
I would use rivets. Reusable, cheap, easy to use.

As far as pressure relief holes go. Never used them. I don't even have a very good understanding of what they are. I know why they are used, but not exactly what they are. I know that on hybrids, you have to drill a hole for venting, but where are pressure relief holes placed. Can anybody clear this up for me? Thanks!
 

LMazza

Well-Known Member
Joined
Nov 14, 2003
Messages
131
Reaction score
0
Havoc, a pressure relief hole is simply a small hole drilled anywhere between the rocket motor and the chute.(Assuming standard motor ejection.) This allows any excess pressure due to a change in altitude to vent and not push the chute out early. Hope that helps!
 
Top