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DD ignorence
Dave post them anyway! I love your terrible av bays  Heart

Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
here's a pile of stuff for 2 3" bays
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DD supply box-
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MARSA54 on a sled.... little tight-
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a 54mm bay showing an inner coupler to hold the bulkheads-
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54mm bluetube bay-

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some 4" bays-
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a 2.6" bluetube bay
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The cheapest DD altimeter available is the DDC22 from Adept Rocketry.  It only does DD, and will not tell you how high your rocket went or record any flight data whatsoever.  It is $35, plus $6 shipping.

You can buy some small plywood sheets from Hobby Lobby to make your sled and bulkheads.  To cut the bulkheads, you will need to have a hole saw.  Or you might be able to get them in Estes sizes from Balsa Machining.

Keep in mind that Estes rockets do not adhere to the standard phenolic and fiberglass tube diameters; so your supply of customizable materials is limited.

Swing by your local library and see if they have Modern High Power Rocketry 2 by Mark Canepa.  It explains everything you'll need to know in pictures and detail.

Locate a gun shop near you that sells FFFFG black powder (FFFG is also okay).  You usually can only get it in a one pound can, which costs about $25 and requires you to sign a registration form.

At this point you are at $75.  Now, as said, you need e-matches or igniters.  You can get cheap ones on Amazon for about $30/100.  You will also need charge wells, or rubber gloves to cut off the tips for powder holders.  You will need some allthread (Home Depot), nuts and bolts, forged or steel eyebolts.

Now you are up to about $110, give or take.  You might be able to use a 9V battery. but depending on the size of your Av bay, you might need a smaller Lipo battery.

And you need wiring.  Radio Shack or an electronics store can help with that.

You will need recovery harnesses that won't burn, and you should invest in a couple of swivels to keep your chutes from tangling and crashing your now expensive rocket.

Finally, you need a way to keep the AV bay in the rocket.  There are two methods:  one is to epoxy it in, and slide your AV bay down the payload tube until it snugs in.  This proves to be challenging, because the payload tube starts to pick up powder residue over time.  The better way is to use pop rivets, or screws to hold the bay in the payload tube.

Depending on what choices you make, you're now at about $140 just to do DD.

Supposing you borrow some BP, and you already have some allthread and HW and plywood around the house, you are still looking at over $100.
John S.
NAR #96911
TRA #15253
Level 1, 2014-Mar-15 -- Aerotech Sumo, H133BS
Level 2, 2014-Jun-21 -- Giant Leap Vertical Assault, J240RL
Level 3, 2016-03-12 -- MAC Performance Radial Flyer, M1101WH, 13,028 feet
(07-16-2015, 06:08 PM)wclune Wrote: Dave post them anyway! I love your terrible av bays  Heart

I just picked up one of Landru;s sleds, an RRC2+, a Lipo and a screw switch for a 4" 38mm bay.    Gonna see what "doing it right" is like Smile

Gonna chop a mini Eagle Claw in half and stick an H268R in it.   ZOOM.    Gonna make a tracker bay in a FW NC for it too.

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(and Ive got a go devil coming....I want what kind of 38mm motor I wanna put in an MD :Smile )

Bill Clune L3 | NAR#88583
Been a launch Director
Founded a Club
MARS Club|SRC|MDRA - Forever
It's not that I can or can not afford it.
I have a way of getting funds if I really want something.
Bottle deposits, Scrap metal, sell something I have in storage, etc.
Nothing illegal.
But I don't have a whole lot of time where my eye sight will be good enough.
Diabetes is in my eyes and vision is going.
It's something I would like to do, I guess you could classify it as on my bucket list.
So is level one, but I don't hold much hope on that.
I can solder, but would rather have it done so I know it works on the egg timer.
The local gun shop owner was a VN Vet and served on the Honor Guard at my fathers funeral.
My father was a WWII Marine in the Pacific Theater so I know I have access to black powder.
He runs a reload shop and his brother shoots only BP shotguns and rifles. History buff.
I'm not looking for altitude out of this, just want to do a DD before it's too late for me.
Grab an RRC2+ $45 bucks and they're simple to fly and use.

Get a coupler and some bulkheads. 4-40 screws and nuts to mount the alt to the board. Some thin plywood will work here. eyebolts, bent wire bolts will work. forged are much better....but not necessary. a length of 1/4-20 all thread and 4 nuts, various washers and two wing nuts.

I recommend either cutting some body tube and glueing it inside the coupler as a stop for the bulkhead, or use two bulkheads a side, one inside the coupler, and oneslightly bigger that still fits inside the bodytube, but not coupler,.

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Forget crazy switches for now.   just twist two wires to arm it.   then tape to the body.

held on this one to 850 mph
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The RRC2 sounds more like what I'm looking for.
I was thinking about a toggle switch hanging outside the av bay to arm it. (have a few on hand)
Like I said earlier, not really interested in getting altitude, just doing a DD.
If I have a successfull flight to 1000' with main at 300' I'd be happy enough to crap my shorts!
I just never did any electronics work before and it's a little scary doing something I haven't done before.
Venturing into the unknown without guidance. (No clubs any where's near me)
I learn better hands on than reading. (not a good reader and understanding)
Toggle switches outside the rocket is bad. Your recovery train can hang up on it and turn your junk off, then you won't have a main. If you can slide your hand up or down the side of your rocket and turn on/off a switch your shock cord can to.
Some altimeters do not tolerate twist and tape replacement for a switch.
I use the RRC3 and program it with the supplied LCD.
Using twist and tape when giving power to the RRC3 results in consistent poor results as seen on the LCD.
The RRC3 will not power up properly when twisting the switch wires together.

The 2 posts below support the need for using a switch and avoiding twist and tape.

From TRF
"I have heard that some (particularly older) electronics do not like the bounce that can be introduced in the circuit by the initial twisting motion - contact can go on and off a couple of times if you aren't careful. I have never seen this in practical terms on my Missile Works RRC2X that I have used it on. I don't think I have used it on my Missile Works Mini or my old Olsen FCP-M2 that I used to have.
I've had bounce from screw switches, as well.
With twist and tape, the key is to immediately press part of the wire together, and hold it there, in tight contact, while you twist the ends.
With screw switches, use a screwdriver with a swivel base on it; use a finger to apply constant pressure to the screw, while you turn it, so that it can't make contact, then drift back out of contact.
Switch bounce can be an annoying pain in the keister."

also from TRF a great post by Fred Wallace

"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...

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...

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

Fred Wallace
TRA 5763, TAP
MDRA Lifer
I need a Kevlar wrap for my truck..."

the entire TRF thread re twist and tape goes into more detail and is found here....

I conclude...with the information avalable to review... that using a switch and not using twist and tape is safest for altimeters.

Tom C.
Tom Cohen

MARS...Geneseo N.Y.

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