Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > The Doctor is In! > Ask the Doctor
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 06-07-2012, 09:34 PM
dk54321 dk54321 is offline
Junior Rocketeer
 
Join Date: Feb 2010
Posts: 17
Default Broken "Landing Gear"

I built a Custom Rockets Ion Pulsar. I liked it so much, I built another one upscaled ~1.5x to BT-60. On both rockets, at least one "Landing Gear" dowel breaks off on each flight. Sometimes two dowels break off, once an entire fin snapped off, it all depends on what hits the ground first.

Any ideas on how to build landing gear that won't break off so easily?
Reply With Quote
  #2  
Old 06-07-2012, 09:46 PM
CPMcGraw's Avatar
CPMcGraw CPMcGraw is offline
BARCLONE Rocketry
 
Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
Default

Quote:
Originally Posted by dk54321
I built a Custom Rockets Ion Pulsar. I liked it so much, I built another one upscaled ~1.5x to BT-60. On both rockets, at least one "Landing Gear" dowel breaks off on each flight. Sometimes two dowels break off, once an entire fin snapped off, it all depends on what hits the ground first.

Any ideas on how to build landing gear that won't break off so easily?


How about a modified version of Yitah Wu's spring-loaded landing pads, or John Rolph's variation ?

Something along these lines should work...
__________________
Craig McGraw

BARCLONE Rocketry -- http://barclone.rocketshoppe.com
BARCLONE Blogsite -- http://barclone.wordpress.com
BARCLONE Forum -- BARCLONE Forum

BARs helping BARs

SAM 0044
AMA 352635
Reply With Quote
  #3  
Old 06-07-2012, 11:22 PM
chrism chrism is offline
Master Modeler
 
Join Date: May 2008
Location: Greenville, PA
Posts: 1,291
Default

Replace the dowels with styrene rod.
Reply With Quote
  #4  
Old 06-08-2012, 04:24 AM
jetlag jetlag is offline
Old BAR
 
Join Date: Aug 2006
Posts: 2,279
Default

Quote:
Originally Posted by chrism
Replace the dowels with styrene rod.


Or carbon fiber rods, and epoxy the fins and pod mounts. Failing that, go for a slightly larger parachute!

Allen
Reply With Quote
  #5  
Old 06-08-2012, 03:48 PM
dk54321 dk54321 is offline
Junior Rocketeer
 
Join Date: Feb 2010
Posts: 17
Default

Here's what I'm puzzling over: When the fin broke off, the glue joint didn't fail. The fin came off complete with glue joint, both fillets, and a layer of body tube. I believe the dowels snapping off is protecting the fins from snapping off. Gluing the dowels back on is easy, but I can only glue the fins back on so many times before I run out of layers of body tube. The dowel is apparently the strongest piece in the system, at least, it's the one part that has never broken.

It looks like I need to find a way for the landing leg to absorb the impact without breaking. The designs I've seen for sprung landing gear appear to absorb longitudinal forces, but not lateral forces. I'm thinking I need to replace the dowels with something flexible and springy.

There's not much room for a larger chute in the upper tube—BT-55 in the upscale, BT-50 in the original. I usually fly at Bong with WOOSH. One thing I like about this rocket is that it doesn't weather**** or drift, but that means it usually lands on the gravel runway instead of in the soft, tall grass. (If I were building a new Ion Pulsar, I could use TTW construction to strengthen that joint, and it might break somewhere else.)
Reply With Quote
  #6  
Old 06-08-2012, 10:13 PM
LW Bercini's Avatar
LW Bercini LW Bercini is offline
BAR Redux
 
Join Date: Jun 2011
Location: Macon GA
Posts: 107
Default

A quick solution may be to install a shock cord, externally mounted at the rear of the rocket. That way, it descends nose first.
__________________
__________________
Lawrence William
SAM #0422
Reply With Quote
  #7  
Old 06-09-2012, 06:25 PM
mwtoelle's Avatar
mwtoelle mwtoelle is offline
Flying since 1977
 
Join Date: Oct 2010
Location: Middle TN
Posts: 452
Default

Quote:
Originally Posted by dk54321
Here's what I'm puzzling over: When the fin broke off, the glue joint didn't fail. The fin came off complete with glue joint, both fillets, and a layer of body tube. I believe the dowels snapping off is protecting the fins from snapping off. Gluing the dowels back on is easy, but I can only glue the fins back on so many times before I run out of layers of body tube. The dowel is apparently the strongest piece in the system, at least, it's the one part that has never broken.

It looks like I need to find a way for the landing leg to absorb the impact without breaking. The designs I've seen for sprung landing gear appear to absorb longitudinal forces, but not lateral forces. I'm thinking I need to replace the dowels with something flexible and springy.

There's not much room for a larger chute in the upper tube—BT-55 in the upscale, BT-50 in the original. I usually fly at Bong with WOOSH. One thing I like about this rocket is that it doesn't weather**** or drift, but that means it usually lands on the gravel runway instead of in the soft, tall grass. (If I were building a new Ion Pulsar, I could use TTW construction to strengthen that joint, and it might break somewhere else.)


My Estes Super Vega has the same problem as your Ion Pulsar with dowels/landing pods breaking fins during landing. One way that I can think of to stop them from breaking is to catch the rocket before landing. Another method would be to rig the model so that body tube is horizontal during descent.

Even TTW construction has its limits. The fins can still break during landing and then you will really have a hard time repairing it.
__________________
'Til next time,

Mike Toelle

NAR 31692 L1

SAM 0373
Reply With Quote
  #8  
Old 06-10-2012, 02:24 AM
mycrofte's Avatar
mycrofte mycrofte is offline
Trust me, it'll work!
 
Join Date: Mar 2009
Location: Illinois
Posts: 1,840
Default

Might build T - slots on the tube so the fins can be replaced easier.
________________
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 06:07 PM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2024