EZ-DD Build

[Art Upton]

That's a sordid tale filled with sighs. In the first rocket, I missed the part in the instructions where two strips of Scotch tape is used to keep the NC from separating. I instead added masking tape to the shoulder. The recovery was fine except it landed on the road and then disappeared. I imagine whoever took the rocket was inspired and will try to figure out how to use it.

I bought two kits because they're $100 each. I built the second rocket before XPRS and launched it twice. I forgot to bring Scotch tape with me so bought a roll at Walmart in Fernley. I then forgot it in the trailer at the RV park so used blue tape with perforations. It worked fine with the first launch, but the main charge blew open the NC. For the second launch, I put too many perforations in the tape but was a beautiful recovery in the desert (with a borrowed Leviathan NC). I repaired the NC with a bulk head.

Yes, sheer pins are the preferred method. Cris told me he doesn't believe the tube can take the sheer force. It's possible to strengthen the tube with thin CA, maybe.

I did all my first DD with simple masking tape on the shoulder with no problems, even on a 5.35" LOC rocket as well as the 4" later. You make the fit tighter, the charge is going to be close by

But then moved to 2-56 nylon screws. Yes I would CA the holes in the Estes tubes, I never bothered in the LOC tubes.

 

[Ronz Rocketz]

The BMS tubes are 0.035" thick. I can't bring myself to trust a cardboard tube with shear pins, even with CA, and especially one that's thinner than typical high power tubing. I fiberglass shear plates of 0.005" stainless steel shim stock into the break points of cardboard DD rockets, and onto the shoulders of light plastic nose cones like the BMS cone too. (Looking at heavy plastic high-power nose cones like those from LOC, I doubt they need anything but a hole drilled.)

I'm planning to get an EZ-DD at some point and build and fly it stock to see how well the tape method works, but I'll probably install plates at some later point (will also mod the nose cone to fly an Eggtimer Mini).

I was gonna strap an Ion to the battery holder but changed my mind and just relied on the beeps.

I would like to see someone show pics of installing sheer pins and have it work successfully at least once. I'll give it a try with a F50 or something.

 

[Art Upton]

I was gonna strap an Ion to the battery holder but changed my mind and just relied on the beeps.

I would like to see someone show pics of installing sheer pins and have it work successfully at least once. I'll give it a try with a F50 or something.

I bought 2-56 screws, more like tiny bolts at the hardware store. I drilled 2 2-56 holes in the tube with the nose cone on.

After ready to put the nose on ready for flight I would push the 2-56 pins into the holes (2 of them, not three) and then cover them with small piece of masking tape to keep them from falling out.

Sometimes after recovery I would have to push the plastic still left in the nose cone's hole into the cone to make room for the next one.

Some folks then ground test the "Chute Cannon" with the Laundry and Pins in it. Would be a good Idea. Just wire the e-match charge outside the Cannon and use your Electron Beam controller to fire it.

 

[Art Upton]

Edit: sometimes on cardboard chute cannons, the charge expands the tube slightly and the nose slides out of the pins forward instead of "shearing" them. No big deal, it still works.

You will notice that if the pin is still in the tube with the masking tape holding it from falling out.

 

[lr64]

Anyone ever try round toothpicks? (This is just an idea.)

Just how much force trying to dislodge it is a nose cone likely to experience? I imagine that if part of the inside of the body behind the nose cone was vented only to a small, backwards NACA duct at the point of lowest pressure on the nose cone, shear pins would not be required. It would create a little extra drag, I suppose. Plus the altimeter would have to be in its own enclosure with its own vent. One could use a smaller eject charge.

 

[Art Upton]

Wood is a bad idea. Nylon tends to shear not splinter and then get stuck

 

[Art Upton]

Anyone ever try round toothpicks? (This is just an idea.)

Just how much force trying to dislodge it is a nose cone likely to experience? I imagine that if part of the inside of the body behind the nose cone was vented only to a small, backwards NACA duct at the point of lowest pressure on the nose cone, shear pins would not be required. It would create a little extra drag, I suppose. Plus the altimeter would have to be in its own enclosure with its own vent. One could use a smaller eject charge.

That is a solution that such a problem does not exist. Nylon shear pins work

 

[cwbullet]

Nylon shear pins work

Any they are cheap. Going cheaper is asking for trouble.

 

[lr64]

So people HAVE tried wood shear pins?

 

[kjhambrick]

The BMS tubes are 0.035" thick. I can't bring myself to trust a cardboard tube with shear pins, even with CA, and especially one that's thinner than typical high power tubing. I fiberglass shear plates of 0.005" stainless steel shim stock into the break points of cardboard DD rockets, and onto the shoulders of light plastic nose cones like the BMS cone too. (Looking at heavy plastic high-power nose cones like those from LOC, I doubt they need anything but a hole drilled.)

I'm planning to get an EZ-DD at some point and build and fly it stock to see how well the tape method works, but I'll probably install plates at some later point (will also mod the nose cone to fly an Eggtimer Mini).

No images on my laptop so short -n- sweet.

I have never used nylon screws as shear pins.

All I have ever used is 1/16 inch polystyrene rods:

You'll find them in the model train dept ( even Hobby Lobby carries them ).

I use one on my 1.9 inch Aerotech-based T'Pring's P'Toy, one on my 2.26 inch Vulcanite, two on my 2.9 inch Glass Nocturnal Missions and I used to use four on my 4-inch Cardboard IRIS.

I've set up my 3-inch BMS School Rocket, HEDLEY for two pins because the av-bay and c-rings made the nose cone pretty heavy ( 205 grams ).

I used to CA aluminum beer can material inside my cardboard tubes to prevent the holes from wallering out but I swear, aluminum cans are ( a lot ) thinner than they were in the 1990's.

I'll try some of that K&S stainless steel shim stock on HEDLEY instead,

Thanks Stephen !

-- kjh

EDIT: attached image as a phone edit

EDIT: Styrene rods work for me ... YMMV ...

 

[cwbullet]

So people HAVE tried wood shear pins?

I can't say I have seen a successful flight. I read about someone testing it on REDDIT. I do not remember the results.

 

[kjhambrick]

So people HAVE tried wood shear pins?

Yes. I have used flat wooden toothpicks but I shook a nose cone free way up there once and went back to 1/16 styrene rods.

 

[SolarYellow]

All I have ever used is 1/16 inch polystyrene rods:
View attachment 668345
You'll find them in the model train dept ( even Hobby Lobby carries them ).

They're about six feet from the rocket stuff in most of the HL stores around here.

They're also great for anchoring NC ballast in PS/HIPS nose cones (all Estes, AFAIK). Just drill some 1/16 holes across the tip, poke these through and wick in some solvent adhesive. Then sand. Nice and lightweight, sands just like the cone, super secure. Not like brass rods that need epoxy or something else to hold them in and are more difficult to sand/fill/hide/etc. Then when you mix your ballast with epoxy, just pour it in and the rods ensure it won't let go under boost.

 

[lr64]

Yes. I have used flat wooden toothpicks but I shook a nose cone free way up there once and went back to 1/16 styrene rods.

Round ones would be stronger, I should think. But styrene rods sound like a good idea.

 

[Art Upton]

No images on my laptop so short -n- sweet.

I have never used nylon screws as shear pins.

All I have ever used is 1/16 inch polystyrene rods:
View attachment 668345
You'll find them in the model train dept ( even Hobby Lobby carries them ).

I use one on my 1.9 inch Aerotech-based T'Pring's P'Toy, one on my 2.26 inch Vulcanite, two on my 2.9 inch Glass Nocturnal Missions and I used to use four on my 4-inch Cardboard IRIS.

I've set up my 3-inch BMS School Rocket, HEDLEY for two pins because the av-bay and c-rings made the nose cone pretty heavy ( 205 grams ).

I used to CA aluminum beer can material inside my cardboard tubes to prevent the holes from wallering out but I swear, aluminum cans are ( a lot ) thinner than they were in the 1990's.

I'll try some of that K&S stainless steel shim stock on HEDLEY instead,

Thanks Stephen !

-- kjh

EDIT: attached image as a phone edit

EDIT: Styrene rods work for me ... YMMV ...

Those work as well. I just like the "heads" on the nylon Screws/Bolts

 

[mtnmanak]

Next is to figure out the decals, I have the waterslide decal material to print my own but need an inkjet printer to do so. Not wanting to purchase a new printer just to print this decal set so looking into places that will let me use their printer for a nominal fee. I have a contact at the local makerspace that has said she may let me use theirs even though it is not really intended for patrons.

Have you considered https://stickershock23.com/ ? Mark could get those done in vinyl pretty quickly.

Well, I got impatient and sprayed the green. This green is very unforgiving and very hard to get even. 

If you use a white primer as the base coat, those neon green and orange colors go on much more even. Something like Kilz works great since it goes on thick and dries quickly.

Yes, sheer pins are the preferred method. Cris told me he doesn't believe the tube can take the sheer force. It's possible to strengthen the tube with thin CA, maybe.

The BMS tubes are 0.035" thick. I can't bring myself to trust a cardboard tube with shear pins, even with CA, and especially one that's thinner than typical high power tubing. I fiberglass shear plates of 0.005" stainless steel shim stock into the break points of cardboard DD rockets, and onto the shoulders of light plastic nose cones like the BMS cone too. (Looking at heavy plastic high-power nose cones like those from LOC, I doubt they need anything but a hole drilled.)

If you use the method @Banzai88 outlines in this thread, it is not too difficult to add some metal shear plates:

https://www.rocketryforum.com/threads/shear-pin-shear-plates-in-your-cardboard-tubes.136706/

 

[Simon Auty]

Doing an Orange Doorknob type paint job on mine it’s now completed.
Will post once I’ve finished the paint.

In the meantime has anyone done a RocSim file?
Tried converting the Open Rocket file but it corrupts everytime

 

[Ronz Rocketz]

If you use the method @Banzai88 outlines in this thread, it is not too difficult to add some metal shear plates:

https://www.rocketryforum.com/threads/shear-pin-shear-plates-in-your-cardboard-tubes.136706/

You do realize there's math and a Dremel involved, right? Just kidding. Thanks for sharing.

 

[Sterk03]

I have 2 flights so far on my EZ-DD. Both were great. First one was at LDRS42 as they launched it just seconds before the wall of rain arrived. It was about 2 hours later in the mud picking up my rocket and the altimeter was chirping away the altitude. Cleaned the mud off it and dried it out and good to go. The second flight 2 weeks ago and the video of that flight I attached. Works as advertised. The only complaint I have is I called a while back to Eggtimer to buy some more plastic plugs to attach the sled to the body tube and have not received any feedback at all about that. They are different then your typical ones and I would like to find some of them from someone. Other then that just need a larger field to try some larger motors. I have not had any nosecone problems. Cheers, Sterk03

 

[Ronz Rocketz]

I have 2 flights so far on my EZ-DD. Both were great. First one was at LDRS42 as they launched it just seconds before the wall of rain arrived. It was about 2 hours later in the mud picking up my rocket and the altimeter was chirping away the altitude. Cleaned the mud off it and dried it out and good to go. The second flight 2 weeks ago and the video of that flight I attached. Works as advertised. The only complaint I have is I called a while back to Eggtimer to buy some more plastic plugs to attach the sled to the body tube and have not received any feedback at all about that. They are different then your typical ones and I would like to find some of them from someone. Other then that just need a larger field to try some larger motors. I have not had any nosecone problems. Cheers, Sterk03

@WillMarchant bought some from Amazon but not available anymore so he mailed me some. Those things like to go flying. For the second flight, I covered them in tape so they don't pop off.

Great flight. Did you bother putting a drogue chute on? Don't think it really needs it. Did you use full or half charge in the wells? Half charge is all that's needed.

 

[Art Upton]

@WillMarchant

Great flight. Did you bother putting a drogue chute on? Don't think it really needs it. Did you use full or half charge in the wells? Half charge is all that's needed.

Here in the Midwest, most go drogue-less. When our group flew at XPRS, they wondered why we flew without Drogues. Trees were the answer. Small drogues do help a bit to spot a rocket really , really up high.

When I flew my Avatar rocket, they said, "Is there a drogue in there?" I said No, No Drogue. It came down quicker and landed close by.

Without drogue, the rocket tends to come down flat, the two tubes doing a "Dance" on the cord.

 

[kjhambrick]

I have 2 flights so far on my EZ-DD. Both were great. First one was at LDRS42 as they launched it just seconds before the wall of rain arrived. It was about 2 hours later in the mud picking up my rocket and the altimeter was chirping away the altitude. Cleaned the mud off it and dried it out and good to go. The second flight 2 weeks ago and the video of that flight I attached. Works as advertised. The only complaint I have is I called a while back to Eggtimer to buy some more plastic plugs to attach the sled to the body tube and have not received any feedback at all about that. They are different then your typical ones and I would like to find some of them from someone. Other then that just need a larger field to try some larger motors. I have not had any nosecone problems. Cheers, Sterk03

Thanks for the videos, @Sterk03 !

NICE !!

What motors did you fly and how high was apogee ?

Thanks again.

-- kjh

 

[WizardOfBoz]

The loss of the plugs confirms my idea that cutting off 1/2" of the body tube for a switchband (even if the big hole for the switch is further forward than the band) is not a bad idea.

Cris's and BMS's designs are really, really efficient. Kind of fun to note the clever details. Regarding the plugs, the holes are about 0.25". The snap rivets that Apogee and Loc sell are 0.155" (about 4mm). If worst came to worst and you wanted to keep the rivet design, you could drill 4 new holes and use smaller rivets. Or, I believe that the "plugs" are actually push rivets with the push pin removed. Something similar to Essentra SVRO-6060B (which is sold by Digikey, among others).

I had the same questions as @kjhambrick. What engines did you use? For my EZ-DD I was thinking F50, G40, or (if I'm feeling like a long walk) a G80.

 

[WillMarchant]

@WillMarchant bought some from Amazon but not available anymore so he mailed me some. Those things like to go flying. For the second flight, I covered them in tape so they don't pop off.

Great flight. Did you bother putting a drogue chute on? Don't think it really needs it. Did you use full or half charge in the wells? Half charge is all that's needed.

The bag-o-100 rivets are back at https://a.co/d/31AnMrZ if anybody still needs them. I'll plan to bring a handful to the next NOVAAR launch.

 

[WizardOfBoz]

Ah, I see that @WillMarchant has provided the proper rivet to get.
Serendipitously, I was finishing up some of the rigging (putting Brummel lock loops on the shock cord) and I dropped one of my plugs. Thought I was going to have to buy some but I found it.

 

[Sterk03]

Doing an Orange Doorknob type paint job on mine it’s now completed.
Will post once I’ve finished the paint.

In the meantime has anyone done a RocSim file?
Tried converting the Open Rocket file but it corrupts everytime

If this is the LOC Doorknob they have on on the web site.

 

[Sterk03]

@WillMarchant bought some from Amazon but not available anymore so he mailed me some. Those things like to go flying. For the second flight, I covered them in tape so they don't pop off.

Great flight. Did you bother putting a drogue chute on? Don't think it really needs it. Did you use full or half charge in the wells? Half charge is all that's needed.

No Drogue chute on mine as Chris says not really needed and I put the match in the well and then filled to the top level and its worked fine each flight.
Sterk03

 

[Art Upton]

I never used rivets, I screw small screws into my payload tubes and couplers. Generally 2 or 3 on Kraft tube rockets. Some smaller rockets only one.

One fiberglass payload/chute cannon I used way too many. There are two holes in the tube on each side for the screw in switches. You can spot one on the left between the screws holding the payload to the coupler. Also piece of masking tape over shear pin to keep it from falling out on the orange.

 

[Sterk03]

Thanks for the videos, @Sterk03 !

NICE !!

What motors did you fly and how high was apogee ?

Thanks again.

-- kjh

1st flight was G79W-6 1250 feet and second flight was a G74W-4 785 feet. I need to check if the altimeter will deploy the main chute
if it does not reach 700'. I was close to it. Rocksim says 935 feet with the G74 but my rocket is heavy 813g/28.6oz I think I overdid the fillets for the motor
tube.

Cheers,

Sterk03

 

[kjhambrick]

I need to check if the altimeter will deploy the main chute if it does not reach 700

Great Q for @cerving !

Inquiring busy-bodies like me want to know too

-- kjh

EDIT: p.s. Thanks for the motors and flight stats @Sterk03