[NRV Rocketry] Suggestions for good L2/L3 Rockets?

Mon Jul 14 21:15:54 CDT 2014

Can I please be removed from this e-mail list? Thanks, Sandra Arthur 

----- Original Message -----

From: "bruce fette" <brucefette at yahoo.com> 
To: "nrv rocketry" <nrvr at nrvr.org> 
Sent: Saturday, July 12, 2014 12:51:53 PM 
Subject: Re: [NRV Rocketry] Suggestions for good L2/L3 Rockets? 

Tweeks, 

As I did my L3, I was guided over and over to make it really strong, and really simple! 
Everything must be redundant and everything must work exactly as planned! 
Yes Tripoli rules are slightly different from NAR rules, so read up! 

So let me tell you what I did to make everything simple.  for example 3FNC 

1) I used LOC tubes, but if you can find a good nose cone to match the ID of a "concrete sonotube", then you can simply fiberglass the sonotube and have a really strong design. My most recent visits to Home Depot and Loews I didnt find any decent sonotubes. They were all warped out of round and beat up. It may be better in Blacksburg. 
I used two pieces of Loc precision 5.5" tubing, for which it is easy to find a matching Loc nose cone. I bought a rotisserie and made cardboard inserts to the tubing diameter so that I could use that to rotate the tubing while glassing and painting. 

2) Since the LOC tubes are not particularly thick, I lined them full length with another piece of loc tubing cut down to coupler thickness. 

3) I made a 6 tube fin design where the tube fins were bolted to the frame with 8/32 TNUTS and bolts = 6TNC. When it lands, if you break a plywood fin, you have to do it all again. If you only bend a tube fin, you can straighten out the bend and you are ready to fly again. (Its all about the rules). If you choose to do plywood fins, be sure to use 1/2" birch plywood. 

4) Dual deploy is a must so that you land at or below the 15 f/s landing velocity. Use two different types of altimeters so there can be no common design fault (have one use beeps and the other use LED flashing so you don't get confused about the eventual altitude). Use a big chute for the main and pop at 500-600 ft so it has enough time to open. And good strong risers, and good strong welded eyebolts. 1/2" plywood and good big fender washers.  1" risers at least 20 feet long and sewn really well by a shoe maker. 

5) Motor mount was redundant, both at the nozzle and up at the forward closure. 

6) You must be able to shut off the redundant electronics without moving the rocket, and you must be able to validate that each squib has fired without any danger to the reviewer. So you need to be able to ascertain the charges shot without moving the rocket in any way. 

7) With care you can also make the motor igniter redundant. 

8) So my L3 was a single purpose built. But I have recently determined that there is a high value in supporting a rather larger diameter motor, and doing your construction so that you can insert various motor adapters and thereby adapt the motor mount to smaller diameters. I do that by inserting a plywood centering ring to adapt the diameter, a smaller motor tube and a plywood thrust plate that can bolt to the original thrust plate. So I can adapt to various motor plans including clusters with various arrangements. 

9) Sure bigger diameter, more drag, lower altitude. The alternative is to do your L3 elsewhere (Arizona, Colorado, Las Vegas, Blackrock etc  = ROADTRIP :)))!) 

Good Luck, 
Bruce 

From: james desposito <jdesposito69 at hotmail.com> 
To: nrv rocketry <nrvr at nrvr.org> 
Sent: Saturday, July 12, 2014 1:55 PM 
Subject: Re: [NRV Rocketry] Suggestions for good L2/L3 Rockets? 

NO it can be a kit 

From: maier.chris at gmail.com 
Date: Sat, 12 Jul 2014 08:58:07 -0500 
To: nrvr at nrvr.org 
CC: tweeksjunk2 at theweeks.org; nrvr at nrvr.org 
Subject: Re: [NRV Rocketry] Suggestions for good L2/L3 Rockets? 

Go motor mount-less.  Fixing a motor mount tube in large airframes proves inflexible if you happen to attend an LDRS or big waiver type of launch.  You end up having to build another purpose but rocket instead of just swapping in a 98mm motor. 

I would recommend against any cluster that lacks a central motor capable of lifting the rocket solo for a cert flight - too much could go wrong for a cert flight, and the highest priority is safety when launching the larger L3 type rockets as well.  Air start your clusters to minimize issues and provide better distance between the rocket and spectators in case there is an issue like one of the motors doesn't light or come up to pressure at the same time as the others. 

Don't the rules still specify an L3 project has to be scratch built? 

Chris  

On Jul 12, 2014, at 7:23, james desposito < jdesposito69 at hotmail.com > wrote: 

After a lot of homework and building a 5'' Big Nuke kit from Loc for my level 3 i found out it is going to hit a altitude of  
over 10,200 feet and not to many places to fly. know I''m thinking more toured a 7.67'' rocket like the   Bruiser-EXP - 3"  from Loc that will stay under 10,000 feet with the smallest M. You have a better chance of keeping your rocket with an 8'' just my opinion. jimmy d  

> From: tweeksjunk2 at theweeks.org 
> To: nrvr at nrvr.org 
> Date: Sat, 12 Jul 2014 02:00:08 -0400 
> Subject: [NRV Rocketry] Suggestions for good L2/L3 Rockets? 
> 
> Hey all.. 
> 
> So we've had a lot of people certing up as of late. They've got their Level-1 
> (H-I motors) and Level-2 certs (J-L).. and some are trying (or at least 
> starting to think about) their Level-3 now (M-O motors). 
> 
> I'm thinking my next big rocket will probably be a 5" (dia) airframe, probably 
> all fiberglass or bluetube. Maybe scratch built (with a nice big ebay for lots 
> of electronics and HAM radio gear).. maybe a kit. I like the flexibility of a 
> multi-motor cluster, like what Giovanni had on his black momba: 
> http://nrvr.org/photos/2012-02-04-5_NRVR-VAST-VT-Launch/IMG_2421.JPG 
> http://nrvr.org/photos/2012-02-04-5_NRVR-VAST-VT-Launch/IMG_2422.JPG 
> http://nrvr.org/photos/2012-02-04-5_NRVR-VAST-VT-Launch/video/MVI_2435.flv.html 
> 
> or maybe a just a more traditional single 75mm: 
> http://nrvr.org/photos/2011-09-10-11_NRVR-VAST-Launch-WEB/2011-09-10-11_nrvr- 
> vast-launch/img_1053.jpeg.html 
> 
> Suggestions.. thoughts.. related questions? 
> 
> Tweeks 
> p.s. we're working out the final details for another Kentland launch in two 
> weeks (26th). 
> _______________________________________________ 
> NRVR mailing list 
> NRVR at nrvr.org 
> http://nrvr.org/mailman/listinfo/nrvr 

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