Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Basic Training - Airframe question
#1
Is anyone using Blue Tube?  I'm wondering how the dimensions match up with the LOC 4" (3.9ID) airframe tubing.  Can I take one of the Blue Tube airframes and a LOC 4" Electronic Bay and graft it onto a BT-3.90, or is the Blue Tube material too big/small?
Dale Stoyer - L3
NAR #91256
TRA #13499
Reply
#2
it should interchange just fine. The only issue i have found you might encounter is the LOC tubes do swell with humidity you may have to sand it a bit. blue tube is great stuff just a bit pricey but like your Grampa always said "you get what you pay for"
Bill Clune L2 | NAR#88583
MARS Club|SRC|METRA|MDRA - Forever
Reply
#3
There is a SLIGHT difference between PML 3.9" and LOC 3.9" tube.  Probably within the tolerance of both.  I would send an email off to Randy at http://www.alwaysreadyrocketry.com be be sure.

Like Bill said I suspect BT to be interchangeable with LOC.  There 5.5" stuff is.  I have some.
John Derimiggio
Reply
#4
Thanks for the advice.  I debated too long though and opted to add the LOC E-bay instead as it was around the same cost as the BT alone.  That leads me to the follow-up question.  I need to 'ventilate' the bay if I intend to use a baro altimeter - but how much ventilation is needed?  I have another payload that will require a 1/4" port in the tube - is that too much for the baro sensor?  How much do I need to worry about the increased drag the port may cause?  On a related note - any tips for mounting rail buttons?  Waiting on mine now from railbuttons.com and have no experience with them.

Dale
Dale Stoyer - L3
NAR #91256
TRA #13499
Reply
#5
Let me be more specific.  I plan to use 3 pressure vents in the bay 120[sup]o[/sup] apart centered between the fins (three fins on the LOC kit) to balance the airflow turbulence created.  Based on the premise that 1/4" venting is sufficient for 100 cubic inches of volume in the bay, my rusty math skills suggest a port size of 3/16" (x3) is sufficient for the 8" E-bay.  That said, I have an onboard camera that I think I can mount to obtain a decent image through a 1/4" opening in the airframe.  I'd like to minimize the perforation of the airframe so I am considering enlarging one or more of the pressure vents to perform double duty.  I guess I am mostly wondering how much venting is too much venting, or if it is not a significant factor in flight dynamics.

Any thoughts?

Dale
Dale Stoyer - L3
NAR #91256
TRA #13499
Reply
#6
In conflict with what you may here from other sources almost any vent hole size and configuration will work fine.  What is more important is what is upstream of the vent hole.  If nothing then anything will work. 

---john
About thirty flights on a rocket with a single 1" vent hole.
John Derimiggio
Reply
#7
Thanks, John.  I prefer that practical to the theoretical.  I'm going to try this camera mount without and external shroud/mirror arrangement, so there should be no problem with upstream turbulence.  Unless you think I should rethink the construction cone based nosecone?  ;D

Dale
Dale Stoyer - L3
NAR #91256
TRA #13499
Reply
#8
John, I like this Dale guy 8)

Also thanks for the hole info
Bill Clune L2 | NAR#88583
MARS Club|SRC|METRA|MDRA - Forever
Reply


Forum Jump:


Users browsing this thread: 1 Guest(s)