To use a switch or twist and tape?

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markkoelsch

markkoelsch

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Hello, after literally a several year delay I am finally starting work to finish my L3 rocket. I had started a thread about it back on Rocketry Planet, but I might well recreate the thread here.

I am debating whether to use switches or twist and tape for the altimeters. I was planning on, and have, the Schurter switches from Missileworks. I have in the last year used twist and tape on a couple rockets. In a way I really like the switches, but on the other hand I like the simplicity and hard to mess up twist and tape.

Thoughts?
 
Twist and tape can put weird power glitches into the electronics and can be hard to disarm if needed, especially if you tuck the wires in after arming. I've used it without issues, but for a cert flight I would go with switches.
 
I've done both. Twist and tape (I tape to the outside of the rocket so I can disarm easily) takes a little longer on the pad, but is much simpler to assemble when building the av bay.

The switches are much faster at the pad and make the rocket took cleaner, but I alway have in the back of my mind that there are more failure points. The switch, the solder joints, the connectors I add for easy av bay removal, etc.
 
You already have the switches. Use them. They give a nice, solid, "click." It is handy to just flip the switch on and off as you are testing the system or if you need to abort.

As the previous poster mentioned, wire twisting can bobble the power. My first altimeter from 1999 blew the drogue charge as I was twisting the wires at the pad. Scared the hell out of me. Today's altimeters may not be as prone to that anymore, but I don't chance it.
 
I have used both with no problems. Conceptually, I prefer a switch because it is very positive, more "professional," and you can disarm easily. In reality I've really liked the simplicity of twisting the wires together.
 
rocketed said:
I have used both with no problems. Conceptually, I prefer a switch because it is very positive, more "professional," and you can disarm easily. In reality I've really liked the simplicity of twisting the wires together.
Click to expand...

Ed, as a former member of TAP, have you tap'd any rockets using twist and tape? That is where I am coming from.

Now, if we are discussing switches, other than the Schurter do we have any other recommendations?
 
cwbullet said:
Simple is better in my book. There is less to fail.
Click to expand...

Chuck, I tend to agree with you here. That is why the way I am setting it up there are no wires outside of the bay, no terminal strips- all deployment charges direct connected to altimeters.
 
mikec said:
Twist and tape can put weird power glitches into the electronics and can be hard to disarm if needed, especially if you tuck the wires in after arming. I've used it without issues, but for a cert flight I would go with switches.
Click to expand...

He said twist and TAPE, not twist and TUCK. I believe 100% in the former, not the latter. This is the ONLY method I use, and disarming is effortless. Every one does it their way, this is mine.
 
I started using switches and did through my L3. Subsequently, I have eliminated switches and terminal strips (now wire charges directly to altimeters). As others have said...less to go wrong.
 
Last edited:
"Twist and tape" is a switch. It may be simpler than dedicated switches, but I don't think there's any objective evidence that it's more reliable. Now if you did twist and wire nut, that I think would be more reliable, but also more bulky.

I personally favor switches.
 
JohnCoker said:
"Twist and tape" is a switch. It may be simpler than dedicated switches, but I don't think there's any objective evidence that it's more reliable. Now if you did twist and wire nut, that I think would be more reliable, but also more bulky.

I personally favor switches.
Click to expand...

John, I understand that- I do have an Associates in Electronics.

What switches do you use, John?
 
Mark
All of us old guys at Bong have used twist and tape method for years. I used the method on my L-3 flight. It has never failed me. Why add another part to fail? Plus I have used twist and tape on at least 4 different brands of altimeters with no problems.
 
I used one of the 110/220 voltage switches. I set it up and I could never get the switch to work. I still do not what was wrong with that switch. I pulled it and used a twist wire.
 
crossfire said:
Mark
All of us old guys at Bong have used twist and tape method for years. I used the method on my L-3 flight. It has never failed me. Why add another part to fail? Plus I have used twist and tape on at least 4 different brands of altimeters with no problems.
Click to expand...

Gary, I am thinking this is the answer too.

I find you statement funny. I am an old guy at Bong...been flying there since 1996.
 
My take on L-3 flights:

Not the time to change up flying technique, do what ever you have been using in past.[as long as "it" has been working successfully]
Look at it like just another flight.

If you do wish to change, fly that way a while before attempting cert flight.

But why change what has been successful for you, for years? [what ever "that" may be] Especially at cert time.
 
CJ, I have done both methods, hence the question. A week ago I was at Bong, and Tim Lehr was doing a TAP inspection of a friends rocket in prep of his cert flight. He was looking at his setup, which uses the same switches I have been using on rockets for more than a decade, and was questioning the switch quality. It got me thinking a bit hence the discussion.
 
I have tried many different switches and always go back to twist and tape. Brown masking tape works just fine even at Mach 2+.
 
Mark you look like a young guy. How old were you when you started to fly at the Bong. 96 was the year I came to my 1st Bong launch.
 
Another $0.02 from a young-ish old Bong guy.... I used to use switches because I liked the cleanliness of having a "real" on-off switch. Then I tried twist and tape; used a mix of twist n tape and switches for years. I had a screw switch fail on me, causing a lawn dart....that's when I stopped using switches.

One failure isn't enough for me to make blanket statements; but I sure do pay attention when recovery fails. In this case, one scary failure was more than enough for me to stick with twist and tape!

-Eric-
 
If I have time to build a sled and line up a switch with vent hole, I'll do it. If space is tight, or it's the night before a launch and I remember I don't have a sled built for the altimeter I want to use... twist and tape it is!
 
crossfire said:
Mark you look like a young guy. How old were you when you started to fly at the Bong. 96 was the year I came to my 1st Bong launch.
Click to expand...

Gary, I will be 47 in early May. So, I guess that would 28 or so at my first launch at Bong.
 
I have been using the featherweight magnetic switches, no holes to drill or align, no wires sticking out of the rocket, no g-force issues (within reason) to deal with, easy to arm on the pad. My latest altimeter uses two of them at each end of the AV bay for dual altimeters.
 
JohnCoker said:
The Schurter voltage selector switches are currently the standard. I'm not sure how the community decided they were the best, but somehow we did. (It sounds like something begging to be tested.)

Schurter SWA1
Click to expand...

Some may believe the Schurter type selector switch to be the standard, I prefer screw type arming switches... I started out using twist and tape, (L-3 done with twist & tape), and moved on to high quality slide switches, key switches, push-push switches and just about every other type switch that I believed would work...

The reason I changed to switches: I was using a Transolve P-2 altimeter using twist & tape... During one prelaunch arming process I experienced both apogee & main charges firing during that arming process... After that big surprise, and doing a bench check of the unit that ops checked good, I had a conversation with John Fliesher... That is when he explained to me about how some altimeters, (his in particular), were susceptible to switch bounce and; how twist & tape if not done carefully, could cause switch bounce and also why he recommended using a good quality switch... The reasoning for this and why switch bounce would be a problem, is that barometric altimeters in particular require re-initialization after the power circuit is broken, in this case, more than likely by switch bounce... If the period of time is to short between power off and re powering up, there is still voltage available in the storage capacitor, etc. During the re-initializing system check, one of the processes is to check for the presence and continuity of electric matches in the circuit. If there is still sufficient voltage/current remaining because not enough time has passed between power off and re-power up, that residual voltage is immediately applied to the apogee and main charge in sequence... Boom-Boom out goes the lights! For those of you that have never had the experience of standing on a ladder next to a 50 lb. rocket when two 5 + gram charges fire in immediate sequence, it is a few seconds of terror, until you realize all your parts are still attached and you can clime off the ladder or pick yourself up from the ground, all in one piece...:eyepop:

For me, I now use switches exclusively, screw type arming switches in particular or in a pinch a good quality DPST/DPDT switch ganged together... Your mileage may vary...:2:

As a TAP member I would caution but not disapprove the use of "twist and tape"...
 
Frederocket said:
Some may believe the Schurter type selector switch to be the standard, I prefer screw type arming switches... I started out using twist and tape, (L-3 done with twist & tape), and moved on to high quality slide switches, key switches, push-push switches and just about every other type switch that I believed would work...

The reason I changed to switches: I was using a Transolve P-2 altimeter using twist & tape... During one prelaunch arming process I experienced both apogee & main charges firing during that arming process... After that big surprise, and doing a bench check of the unit that ops checked good, I had a conversation with John Fliesher... That is when he explained to me about how some altimeters, (his in particular), were susceptible to switch bounce and; how twist & tape if not done carefully, could cause switch bounce and also why he recommended using a good quality switch... The reasoning for this and why switch bounce would be a problem, is that barometric altimeters in particular require re-initialization after the power circuit is broken, in this case, more than likely by switch bounce... If the period of time is to short between power off and re powering up, there is still voltage available in the storage capacitor, etc. During the re-initializing system check, one of the processes is to check for the presence and continuity of electric matches in the circuit. If there is still sufficient voltage/current remaining because not enough time has passed between power off and re-power up, that residual voltage is immediately applied to the apogee and main charge in sequence... Boom-Boom out goes the lights! For those of you that have never had the experience of standing on a ladder next to a 50 lb. rocket when two 5 + gram charges fire in immediate sequence, it is a few seconds of terror, until you realize all your parts are still attached and you can clime off the ladder or pick yourself up from the ground, all in one piece...:eyepop:

For me, I now use switches exclusively, screw type arming switches in particular or in a pinch a good quality DPST/DPDT switch ganged together... Your mileage may vary...:2:

As a TAP member I would caution but not disapprove the use of "twist and tape"...
Click to expand...

Fred, are you talking about the screw type switches like the ones sold by Aerocon, and we're used on the Altaccs?
 
markkoelsch said:
Fred, are you talking about the screw type switches like the ones sold by Aerocon, and we're used on the Altaccs?
Click to expand...

Yes, the ones sold by Aerocon, identical to those used on the first version of Scott Bartel's ALTACC. I have also made a screw switch version of my own, using a screw, two blind nuts, a block of wood with a hole drilled through two sides, then soldering a wire to each blind nut then mounting the blind nuts on opposite sides of the wood block. When you screw through one blind nut and the screw makes contact with the opposite blind nut, it completes the switch circuit... Tightening the screw snugly/tight ensures a bounce free contact/connection, no matter how high the G-force is....
 
With a switch, there is 0% chance of the tape coming off and the wires separating. Just a thought.
 
Yes I did Tap several rockets that used twist and tape and several that used switches. Since there was no "rule" on it, and both worked fine for me, I left it up to the candidate. I asked the candidate specifically if the electronics had been tested. I always tested my altimeters with a home-made vac chamber with the same ematches I was going to use on the flight the night before. I even made sure the ematches were from the same batch and volt-meter checked them all before testing or for flight. Might want to test your electronics and see if you can "bobble" the power and light an ematch. -Ed (old guy from Bong)

markkoelsch said:
Ed, as a former member of TAP, have you tap'd any rockets using twist and tape? That is where I am coming from.

Now, if we are discussing switches, other than the Schurter do we have any other recommendations?
Click to expand...
 
Bat-mite said:
With a switch, there is 0% chance of the tape coming off and the wires separating. Just a thought.
Click to expand...

The tape is not holding the wires together, just holding them against the side of the rocket. Or at least it better not be doing so!
 

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