Side Access into carbon fiber at mach 1.45?

[IceBerg]

I was hoping to get some opinions on side access avionics bays past mach. I am concerned that a large cut away in a 6 inch diameter carbon fiber tube would compromise structural integrity of the airframe. What are your thoughts?

 

[Nytrunner]

How large are you talking exactly? And what sort of hatch are you designing (hinged,vs pinned panel)

Since I assume you're accessing an internal bay, running threaded rods between the bulkheads with collars could turn them into compressive structural elements.
If a pinned panel is used, you're transmitting some load back through the panel.

 

[IceBerg]

I was thinking about a decently large pinned panel. (Enough space to get my hand in) Good idea on the threaded rods for the compression ill definitely put that into practice.

 

[tfish]

Also to take into account...

How fast (load on the air frame) is the planned flight?
And sealing the hatch, other then the required altimeter vent holes, from the air stream so you don't spoof your electronics.

I've seen ebays built into coupler tubes that have an opening cut into the side. This opening is for access to batteries and altimeters. It's held in place by machine screws. This would maintain most of the body tubes integrity other then the screw holes.


Tony

 

[rfjustin]

Um... why is this needed?

 

[TimothyG]

I’m doing a 2x3” hatch on my 4” fiberglass airframe for level three. I have three flight computers and three cameras that are going to be activated through the hatch by two position switches. Plan is to also have the hatch cover contain a switch locking plate that ensures switch’s can’t move under acceleration. The rocket Utah state university built a decade back had enormous cut out access hatches for accessing internals for fine tuning. Think 5.5” airframe with 8x6 hatch.

 

[G_T]

I double walled the bay on mine.

Instead of a single large cutout, consider minimally sized access holes for controls and connectors.

Gerald

 

[DavidMcCann]

However you cut it, I think accessing it at that speed will be difficult.

 

[Igotnothing]

Not sure about that David. I think a hand would go right through most carbon airframes at Mach+.

Removing the carbon slivers will be a PITA.

 

[JimJarvis50]

However you cut it, I think accessing it at that speed will be difficult.

Well actually, I got a picture of my P-motor booster, under thrust, at about that speed. Wasn't all that hard.

But seriously, I suspect that with the bay providing support, that it would probably work. That said, I'd find another option.

On my 3-stager, I cut "slot antennas" in the sides of the 2nd and 3rd stages to allow wifi to pass into the bays in the carbon air frames. They were vertical, 3-inch slots. Those air frames survived the flight at much higher speeds, but not as much air frame removed.

Jim