Hiding Schurter switch

Why can't the Schurter 110/220 Switch be hidden "under" the Sustainer and coupler joint? What I mean to say is pull the 2 halves apart slightly to gain access, arm switch and push together. I see most rockets have a switch band and don't really see the purpose. Or they have them on the end of the Ave-bay. Just asking to learn. Maybe I am missing a need.

I've never used a switch band. Just a hole where the two halves meet so each side has a half hole. That's for the altimeter port as well as an internal screw or pushbutton switch but I don't see any reason why you couldn't do a similar thing with your switch. My $.02...
-Ken

When you push the halves back together there is a chance to increase the pressure in the bay and when that pressure leaks back out... apogee detection goes off and you have an unhappy day

You definitely want the switch exposed in some fashion, the rocket should only be armed once it's loaded on the rod/rail. Plus, as junkyard mentions, once you've turned on the switch & armed your electronics you run the risk of triggering something with the pressure sensor on your altimeter no matter how gently you try to push the halves back together. Safety first and all that jazz.

Ok, makes sense sort of. Wouldn't the pressure compensation vent holes take care of 1/2 inch of "compression" as you put them together? With the bottom of the Ave-bay part sealed to protect against gases how could pressure be added to it (Ave-bay)?I am talking about turning the switch on after rocket is loaded on rail. I ask why not to doubt but to understand.

On my first DD build I used a small toggle switch inside the AV bay that was accessed via a hole in the lower section of the coupler. Basically the same set-up that Lance is asking about. It has worked fine...and I will not use this method again.

I don't see how there is any possibilty of a pressure spike affecting the altimeter. Some pressure might build up momentarily in the booster tube below the AV bay when you are sliding the coupler back into place, but that will be relieved by the vent hole in the booster. If pressurizing the booster tube affected the pressure in the AV bay, you would have a whole lot of problems (like where all that gas would go when the black power charge goes off :eyepop

My reason for not using this method again is that it's not as direct as switching from the outside - it is much easier to go through a vent hole than to lift the upper half of the rocket. Especially as the rockets get bigger/heavier. And if you are going to use shear pins on the lower section (something that I've started to do on bigger/heavier rockets), it makes separating the sections on the pad unfeasible.

Good points, thanks.

I prefer to not use a switch band and for me there are advantages to placing the switch in the sustainer/payload seam.

- It is easy to do the split hole and there is no switch band to futz with. A Dremel with a 1/2" sanding tube gets it started and a fine 1/2" rat tail file to finish and the body tubes are done. It takes a little practice, but its easy.
- There is no switch band to paint and have match.
- There is more coupler length to lay into the sustainer.
- The switch makes a nice "key" to keep the two halves aligned and your paint job aligned
- It is one less part (Body Tube) to sand so it matches/aligns flush with the other body tubes. When I have them aligned, the key keeps them that way.
- The switch is recessed and almost flush with the tube. Even with a switch band I will enlarge just the outer body tube hole so the switch is recessed - best done before glueing the coupler/switch band tube.
- and, I like the way it looks - clean and functional.

To each his own...

My last build, I used a LOC av-bay. These have their stiffy--quarter-inch thick paper. The thickness let me recess the switches into the av-bay itself, with corresponding holes drilled in the airframe.

So, this:

And then, this:


N.b: The screws were eventually countersunk prior to final painting.



Later!

--Coop

This is what I am trying to explain (green dot represents the switch). I have in the past trimmed the outer lip off the switch to see if it would fit flush with the airframe. I think I could do the same and have it flush with the coupler, then when I put the 2 halves together it would be under the sustainer.
I like all the solutions listed above and am just thinking if there is another way.

Order a 3D printed sled from Landru or build your own and mount your switch inside your av-bay and save yourself the headaches.

Put the switch on the electronics board and drill a small hole through the sustainer and coupler that are aligned with the switch. Use the hole as a vent or tape it if not a vent. If you do not like tape, tap the hole and use a screw.

waywayanda said:

I prefer to not use a switch band and for me there are advantages to placing the switch in the sustainer/payload seam.

- It is easy to do the split hole and there is no switch band to futz with. A Dremel with a 1/2" sanding tube gets it started and a fine 1/2" rat tail file to finish and the body tubes are done. It takes a little practice, but its easy.
- There is no switch band to paint and have match.
- There is more coupler length to lay into the sustainer.
- The switch makes a nice "key" to keep the two halves aligned and your paint job aligned
- It is one less part (Body Tube) to sand so it matches/aligns flush with the other body tubes. When I have them aligned, the key keeps them that way.
- The switch is recessed and almost flush with the tube. Even with a switch band I will enlarge just the outer body tube hole so the switch is recessed - best done before glueing the coupler/switch band tube.
- and, I like the way it looks - clean and functional.

To each his own...

View attachment 256891View attachment 256892

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This is exactly what I was trying to get at! Looks awesome Bill!
-Ken

accpool said:

Ok, makes sense sort of. Wouldn't the pressure compensation vent holes take care of 1/2 inch of "compression" as you put them together? With the bottom of the Ave-bay part sealed to protect against gases how could pressure be added to it (Ave-bay)?I am talking about turning the switch on after rocket is loaded on rail.

Click to expand...

Ah, yeah you (and Dad Man Walking) are right - the key piece that wasn't clarified was that if a switch band is used then usually the altimeter sampling holes are also on the band. I had gotten it into my head that you were putting the sampling holes underneath as well, I'm going to assume that's not the case. If indeed your altimeter sampling ports are below (as in 'below-further-aft-on-the-tube', not 'below-underneath') the coupler joint then there shouldn't be any problem.

accpool said:

I ask why not to doubt but to understand.

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No worries, always good to ask questions. Exactly as you say, that's how new methods are discovered.