Updates...

[Joshua F Thomas]

If you're using the 3.7v, you'll have to choose between 3 in series ( = 11.1 v ) or 4 in series ( = 14.8 v ). How useful any of these are depends on the wiring you're using and the length of your launch cord. If you have a really long cord from the batteries to the pad, use the higher voltage.

My suggestion is to get a battery holder and build that into your kit. Take a look at this: https://www.ebay.com/itm/26650-Dual...-2-pcs-Brass-SMD-clip-US-Seller-/132490043800

Those are for 26650 sized cells; choose a holder for the correct size. Perhaps Battery Bill has something appropriate? In my controller, those holders are superglued to the bottom of the case. 14g wire is soldered between the terminals to put them all into series. To recharge, just remove the batteries and put them in your charger.

The 3500mAh are more than sufficient. You need peak discharge, not total capacity. Look for the CDR rating of the battery. 10A is what you want minimum. 15A is better, and beyond that is overkill unless you're going for large cluster launches.

 

[Ronz Rocketz]

I'll get that. I forgot to check if they were the 26650 size or not. They have pandemic measures in place so had to meet the salesperson in the parking lot with a facemask and explain what I was looking for who then retrieved it from the store. It felt very drug dealish.

If you recommend 14ga, should all of the wiring be 14ga including the wire to the rocket?

Eventually, my controller will look like this but in my version, you have to enter a code to cancel the launch but the timer would still count down to 1.0.



After that will be a launcher using tritium as a power source.

 

[Joshua F Thomas]

If you don't mind me saying, those controllers are.... aggressively complicated. If you are asking questions like "what size wire should I use" and "do I need resistors on an LED", you need to start with *much simpler* launch controller design. Get it simple, and solid, before a bells-and-whistles version.

Wire is always a trade off between size (thickness), ease of use (how stiff is it) and how much current it can carry. Thicker wire carries more current and has less voltage drop, but is harder to work with and takes more space. Your main question becomes "how much current/voltage do I need this wire to carry?".

If you're using a design where the power source (batteries) are a long distance from the launch pad, for example they are together with your launch button, then you're going to need much thicker wire to prevent voltage loss to the igniters on the pad. You can use this calculator to play around with different options: https://www.calculator.net/voltage-drop-calculator.html (make sure to select DC voltage).

18 AWG will drop about 0.75 volts over 30 feet if your load is 2 amps. The actual current to fire the igniters may be lower, but choose a bad case to be conservative. That 0.75 volt drop isn't terrible if you're using 12 volts, but it's a lot worse if you use 6 volts. 14 AWG will drop only 0.3 volts.

You can probably get away with 18 AWG if your voltage is high (12v+) and your length is 30 ft or less. For greater length you'll need a beefier wire or more voltage. Note that for connections where you expect a lot of momentary current - like directly between two batteries - using hefty wire is always a good idea.

You can avoid many of these problems by using a two-part system, where the battery box and launcher are two seperate devices. The battery box sits at the pad and is controlled by the launcher, connected by wire. The launcher can use thin wire as it only sends a signal to the battery box to enable a relay, which switches the batteries directly to the igniter. The distance is very short and you have almost no voltage drop. This is particularly important if - like me - you're doing clustered launches where you need to reliably light three or more igniters all very quickly.

The design I went with (see this thread: https://www.rocketryforum.com/threads/my-12v-cluster-launch-controller-build.160168/) is that type. It's based off Harry Stine's Handbook of Model Rocketry and a design by the late Micromeister forum user. It's fairly uncomplicated, as these things go.

 

[Ronz Rocketz]

The winds calmed to 10mph and the City is closing the parks tomorrow for three weeks so decided to venture out. I may end up sneaking on the local park, or not.

I finally got a decent 16ga speaker wire for the DIY launcher which works great. I tried the suggestion of using wadding in the motors instead of plugs to hold the starter/igniter, but failed miserably so went back to the plugs. Could be the launcher but doubt it...

The GoPro3 is old so bought a cheap replacement on Amazon to try. So far, the quality looks like crap. It can run at 240fps/720p which is nice but the picture is grainy and the sound is awful. I figured out that the audio has a buzzing at 240fps and 120fps. I brought the GoPro with us as backup but used an old 8Gb SD card which doesn't seem to be working so would only run for 12 seconds.

Several of the rockets had rough landings. Not sure what happened with the Lunar Scout's A10-0T motor, It seemed to fall out somehow just after launch. I forgot to add the streamer to the Galaxy Rescue. One fin cracked but might be from colliding with the NC instead of the ground. The Orion Shuttle flight improved with more weight in the NC.

After losing the Bull Pup 12D, I decided to build a XL version with a BT-60. It also has a home made baffle inside. The B6-4 worked fine so decided to try again with a C11-3, but the parachute got a small tear and I swapped it with another 9" chute. However, the second chute got shredded and the rocket cracked three fins on the hard landing. I chose the smaller chute because the sim was showing it landing 50m from the launch site, and I didn't want it doing a DC/SAM into the golf course. It probably could use a 15" chute instead.

The scratch built Goblin BT-60 worked great except the parachute got tangled with the swivel. Fortunately, no damage.

 

[kuririn]

Ron, the A10-0 might have prematurely blown through the front of the propellant.
I have been seeing mini engine CATOs recently. Never saw those before.
Yeah, renewed lockdown SUCKS. I was prepping some MicroMaxx rockets for launch and the next day the guv made the announcement. But understandable, I hope they get this surge under control.
At least the Koko Head Range is still open.
Laters.

 

[Greg Furtman]

My next project. Turns out the button I ordered is latching and not momentary. I’m thinking of using it anyways.

You need one of these.

https://www.ebay.com/itm/12V-19mm-P...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

[Ronz Rocketz]

At least the Koko Head Range is still open.
Laters.

Yeah, thinking of going there tomorrow. They probably were able to prove they can maintain social distancing at the tables.

You need one of these.
https://www.ebay.com/itm/12V-19mm-P...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

Tempting but shipping from China has been very dubious lately.

 

[Joshua F Thomas]

After losing the Bull Pup 12D, I decided to build a XL version with a BT-60. It also has a home made baffle inside. The B6-4 worked fine so decided to try again with a C11-3, but the parachute got a small tear and I swapped it with another 9" chute. However, the second chute got shredded and the rocket cracked three fins on the hard landing. I chose the smaller chute because the sim was showing it landing 50m from the launch site, and I didn't want it doing a DC/SAM into the golf course. It probably could use a 15" chute instead.

If you're worried about 50m of horizontal drift, you really need a bigger field, or lower flying birds.

 

[Joshua F Thomas]

Yeah, renewed lockdown SUCKS. I was prepping some MicroMaxx rockets for launch and the next day the guv made the announcement. But understandable, I hope they get this surge under control.

You guys need to come to the east coast where we have this under control.


I kid, I kid....

 

[Ronz Rocketz]

The field is 150m wide. That's as big as the parks get here. I usually set up about 50m in to avoid the monkeypod trees. Plus wind, doesn't give much leeway.

 

[Ronz Rocketz]

My resistors arrived today. Now I have resistors for the next 5 generations.

 

[Joshua F Thomas]

Resistors are dirt cheap. There’s no good reason not to just keep a good supply on hand.

There are a few weird cases that you need in high power circumstances, like 10W power resistors, that can be bought as-needed. Those are larger and more expensive.

 

[Ronz Rocketz]

Resistors are dirt cheap. There’s no good reason not to just keep a good supply on hand.

There are a few weird cases that you need in high power circumstances, like 10W power resistors, that can be bought as-needed. Those are larger and more expensive.

I’m 52 years old and this is the first time I’ve said in my life, I need a resistor.

Regarding USPS and shipment problems, I ordered a new GoPro 8 to “retire” my GoPro 3. I ordered it from Costco and UPS delivered two days later. I paid $11 for shipping.

Ive lost several Amazon packages over the past months and they just send me a replacement. I wonder if there’s a big hole somewhere where they collect the lost packages or if they eventually make it back to Amazon.

 

[Ronz Rocketz]

Home Depot switched to the Paint+Primer line and a dollar cheaper.

 

[Joshua F Thomas]

I've had ok success with those. I'm mostly using the regular Rustoleum stuff, or this, whichever is less expensive.

 

[OverTheTop]

We are seeing lots of Rusto 2x downunder now. Seems to work well if I keep the coats thin. Is getting a bit rare at our hardware shop currently. Must be lots of spray painting during lockdown.

 

[Cape Byron]

We are seeing lots of Rusto 2x downunder now.

I've tried the Rustoleum 2X a few times and hated it sooo much. Nasty reaction after 3 weeks between coats (busy farmer) on my Apex repair.



It's the main reason I'm going back to airbrushing. YMMV.

 

[Ronz Rocketz]

The spray paint ship arrived and Walmart was fully stocked. Picked up a couple high gloss paints.

Newest rockets are an 18mm Hi-flier, ASP V-2, and Apogee’s Green Vortex.

 

[kuririn]

I would be very interested in a flight report on the Green Vortex.
Saw the plans in the Apogee newsletter.

 

[Ronz Rocketz]

I was wondering if it spins. Favorable winds tomorrow but nowhere to launch.

The plans call for 8’ of Kevlar. I did 1’ of Kevlar and 4’ of elastic. I also paper fin’d and CA the edges.

 

[125cc]

Rockets ready to fly...

View attachment 426859

Mind if I ask what model the one on the right is? Looks pretty cool!

 

[Ronz Rocketz]

Mind if I ask what model the one on the right is? Looks pretty cool!

Estes Cobra. Picked it up from the LHS. I’ve been afraid to fly it until the winds die down (and the parks reopen). It has cool sidewinder missiles on the back. Closest thing I’ve built to a model.

https://www.acsupplyco.com/estes/7228_estes_cobra.html

 

[125cc]

Nice one! Thanks. Might give one of those a go!

 

[Old School Doug]

The spray paint ship arrived and Walmart was fully stocked. Picked up a couple high gloss paints.

Newest rockets are an 18mm Hi-flier, ASP V-2, and Apogee’s Green Vortex.

View attachment 429063

Started on the Green Vortex as well. Got the fins cut and started filling and sanding when I discovered I had no BT55 tubes on hand. Looks like I'll be at the mercy of the USPS before I can resume the build.

 

[Ronz Rocketz]

The completed Green Vortex and ongoing SWAT clone. I papered the fins with Avery label sheets, sanded the edges, and sealed the edges with thin CA. I like it.

 

[mo2872]

Miss my SWAT.......perished in a shop fire.......RIP

 

[Ronz Rocketz]

While priming the SWAT, I noticed one of the back fins was loose. Mistakes were made. I used thin CA along the primer crack. I made the fillets from wood filler instead of epoxy.

After a bit, I applied two coats of RO 2x high gloss but the area around the loose fin wasn't right. A day later, I used a steel wool to the area and lightly down the side. I tried a third coat of high gloss and got orange peel along the side of the rocket.

I think I got (day old) CA residue on the steel wool which reacted with the high gloss. I'll wait a day, sand it down, and try another coat of HG.

Update: Just tried to paint the HG on the cone and got the same result. Perhaps it's the weather. I'll have to sand down the NC also and try again tomorrow. Today is not a good day for painting.

 

[Ronz Rocketz]

Sanding and repainting worked great with the same rattle cans. Current theory is the humidity. Several of my house doors are sticking.

I underpowered the rocket. I only had screw locks and only the 18mm would fit in the rear nozzle. OR say 150’ with C5-3. If it lawn darts instead, I’ll cut off the nozzle and install a proper MM. I did end up taking liberties with the paint and decals.

 

[mo2872]

Man, where’d you find a SWAT in Hawaii???

 

[Ronz Rocketz]

Jimz...