Quantcast

Some design and build considerations for beginning scratch builders.

The Rocketry Forum

Help Support The Rocketry Forum:

Senior Space Cadet

Well-Known Member
TRF Supporter
Joined
May 23, 2020
Messages
418
Reaction score
164
I went to my first club launch.
I launched one of my scratch builds, a couple times, and brought it home unscathed.
Some other rockets, at this event, weren't so lucky.
It would appear that failure of recovery systems is fairly common.
The most common result is a crumpling of the first several inches of body tube.
If you have a really long rocket, cutting off a few inches, and then adding some weight to the nose, will fix the problem.
I would suggest considering a replaceable front section on the rocket as an insurance policy.
I saw one rocket become unstable and lawn dart severely, yet it received no damage, because it was fiberglass.
I looked into fiberglass parts and they are really expensive, but the cost might be justified, in the long run.
I've bought baffles for a couple of my builds. I'll probably glue half into the bottom section of body tube and leave the other half unglued. Hopefully, the upper tube won't come off when the ejection charge goes off.
 

dr wogz

Fly caster
Joined
Feb 5, 2009
Messages
5,508
Reaction score
814
Location
Land of Poutine!
build it to fly, not to crash.
(understand why they crashed, and you can learn from them. while recovery failure is common, it shouldn't be on every 2nd or 3rd rocket. something is wrong there. our club will see one or two. The few big events 've been to, only a few there as well...)

Build light, flies right.
Build straight, flies great!
 

neil_w

Chuffed as ninepence
TRF Supporter
Joined
Jul 14, 2015
Messages
9,535
Reaction score
2,708
Location
Northern NJ
It is commonly said that the up part is the easy part. Down is harder, and the source of most failures.
build it to fly, not to crash.
+1000
I've bought baffles for a couple of my builds. I'll probably glue half into the bottom section of body tube and leave the other half unglued. Hopefully, the upper tube won't come off when the ejection charge goes off.
Not recommended! Some sort of secure retention should hold the airframe together, either glue or screws, or something.
 

gna

average joe-overbuild member
Joined
Sep 10, 2014
Messages
387
Reaction score
84
What size were these rockets that failed? While it's not uncommon to have recovery failures, it shouldn't happen that often. With LPR the problems are usually parachute related--chute wadded, chute stuck in body tube, chute line breaks. Talcum powder and folding and rolling better help here.
 

heada

Well-Known Member
Joined
Jan 18, 2009
Messages
3,381
Reaction score
691
Location
Indianapolis, Indiana
Solid fiberglass parts are resilient but $$$ and HEAVY. Hard to justify for smaller rockets. Doing a fiberglass wrap or tip to tip on the fins can give added strength without as much weight and cost.

Using a baffle as a coupler can work but it isn't standard and you'll want to make sure that it has enough air-flow that the back pressure wont blow it out the rest of the way. Another option is a piston. Some people don't like pistons but I've found that as long as it is similar materials (cardboard piston in a cardboard airframe) that they work well.
 
Top