First Dual Deploy Attempt - questions???

[jdud]

Well, I'm going to attempt my first DD at our next club launch. The rocket I plan to use is either an upscale Nike Ram I am currently building (based on a Semroc thick walled, 225 tube) or a 2.2" diam. LOC Black Brant X. Both rockets have 29mm mounts, so an H motor should really make them scoot. The altimeter being used is a Missile Works RRC2 mini. I'm trying to keep everything simple for my first attempt.

Question 1: Do the HotWire ejection canisters available at Newtons 3rd work well with the RRC2? If so, will one 9V battery fire them off?

Question 2: Since these are both relatively small rockets for H or I motors, could breaking mach be a problem? I know the altimeter needs to be set differently if breaking mach - but how do I know if it will indeed break mach or not?

Question 3: Could anyone post some pictures of their wired altimeter set up - especially a smaller one like I am trying to put together? A picture is worth a thousand words.

Thanks!

 

[blackjack2564]

1.Don't know on this one. I use e-matches

2.By simply setting the mach delay for 4 seconds, you can aleviate the issue entirely. This will make the alt.immune to the shock waves created during mach transition that cause malfunctions. By the way you don't have to hit mach to have problems, just approaching it can trigger irregularities. A flight approaching .8 mach can be trouble. This is where the shock wave begins to develop actually before hitting mach.

You could also run a simulation in Roc Sim, but I always run a mach delay anyhow just "in case" First thing I do with a new altimeter is set the delay for 4 sec then I never have to worry or remember to do. It is very unlikely you will need a higher setting till you start flying some pretty exotic stuff. 4 seconds in Mach is a long time.
Having seen many people forget or just not know any better, and suffer the consequences, I highly recommend doing it.

3 if you could be a little more specific as to what your trying to do,I have many bays set up different ways, and I'll be glad to post pics and descriptions for you. Is there a specific problem your having?

 

[kandsrockets]

To answer the ejection canister they do work with the mini.

 

[jdud]

Thanks for the help!

Jim, I'd love to see some pictures of your Little Dog set up. This is about the same size ebay I am trying to build. I wanted to see where you mounted your switch and what kind of switch you used. As best I can recall, you had a hole drilled through the ebay and the joint of the airframe sections. This allowed you to get to your switch and lined everything up.

If I go the ematch rout, does Dennis sell ematches at Orangeburg, or should I look into getting a dip kit to bring my own?

 

[kandsrockets]

Here are some pictures of how I have my e-bay for a 2.6" dia rocket. I have my switch mounted on the board that the place for the screwdriver is on the opposite side as the alt.

 

[Pantherjon]

Thanks for the help!

Jim, I'd love to see some pictures of your Little Dog set up. This is about the same size ebay I am trying to build. I wanted to see where you mounted your switch and what kind of switch you used. As best I can recall, you had a hole drilled through the ebay and the joint of the airframe sections. This allowed you to get to your switch and lined everything up.

If I go the ematch rout, does Dennis sell ematches at Orangeburg, or should I look into getting a dip kit to bring my own?

I am pretty sure Dennis has e-matches..You can drop him an e-mail at rocketryzone at earthlink dot net...

 

[Pantherjon]

1.Don't know on this one. I use e-matches

2.By simply setting the mach delay for 4 seconds, you can aleviate the issue entirely. This will make the alt.immune to the shock waves created during mach transition that cause malfunctions. By the way you don't have to hit mach to have problems, just approaching it can trigger irregularities. A flight approaching .8 mach can be trouble. This is where the shock wave begins to develop actually before hitting mach.

You could also run a simulation in Roc Sim, but I always run a mach delay anyhow just "in case" First thing I do with a new altimeter is set the delay for 4 sec then I never have to worry or remember to do. It is very unlikely you will need a higher setting till you start flying some pretty exotic stuff. 4 seconds in Mach is a long time.
Having seen many people forget or just not know any better, and suffer the consequences, I highly recommend doing it.

3 if you could be a little more specific as to what your trying to do,I have many bays set up different ways, and I'll be glad to post pics and descriptions for you. Is there a specific problem your having?

2a: The waves develop at approximately Mach 0.76 to 0.80 like Jim mentions..Lots of turbulence in that region of speed..When the object actually achieves Mach 1.0(or the speed of sound) those waves collapse. This is what causes the 'sonic boom' when surpassing the speed of sound...

I am not an aeronautic guru..But, I think I got that info correct...

 

[Diosces]

Here's some pics on my first 2.6 Dia Ebay i made. I had some issues with charge size and canister alignment using both newton's third and pratt canisters. I eventually went with PVC pipe fitting for the charge holder and ematch as seen in last pic

Jaguar Ebay initial
Jaguar Ebay final

My recommendation is to thoroughly test ejection set-up with all the final recovery components loaded, saves a lotta of heartache.

 

[blackjack2564]

jdud.......I just twist and tape my switch wire to payload. This covers most flights. If I expect Mach I will tuck it in.

You can mount your switch directly to the coupler and the half hole installation will close right around the switch. OR....increase the hole to 1/4 so a screwdriver will fit through to switch mounted on the sled. This has been done on bays your size, so I now it works.

I used 3/16 hardware to save space and weight.
The fixed eyebolt is on rear of bay, this is the apogee side and the long fall and twisting motion of can't loosen it. This way the removable eyebolt remains in the payload, unaffected by twisting motion after main deploy,at low altitude, where it doesn't matter.
Just cut off eyebolt to fit a coupler nut and a few drops of CA keep it from loosening.

There is no room for a battery box in this configuration. a wire tie holds it in front to back and tape side to side. It will just slide in, a wire tie around the side will NOT fit.
You can drop the rod from center to off center of bp, if you want, giving more room for larger alt.

3 rivets hold bay in. Mounted 1 1/2 in. from edge of tube. 5/32 bit is size needed to drill holes. Vent size is also 1 5/32 hole, but as mentioned 1/4 is fine for reaching a switch.
By the way if you want shearpins in NC 2 # 2-256 nylon screws are the ticket!

The removable eyebolt is held on with washer and lock nut.

The rocket was the prototype for DD little Dog so the payload is 24in rather than 16. and the bulkplates wood instead of G-10
For ejection charge 1.5 grams is used at apogee and 1gr for main.

You will note this design is very simple, allows for the sled to be transferred to any other rocket with the same center rod design, and eliminates all the extra hardware. I use a section of soda straw slipped over the match and taped to it, fill with bp and hooked up direct to the alt. I do not use switches, terminal blocks etc. eliminating all these points of failure. Many due use them successfully but I've seen too many failures due to them. The less that can go wrong......the less that will.

Also you can use mini Xmas lites, I used to and Pantherjon still does and I'm sure he will show you how at the launch. Perfect flite sells a kit on their site.
https://68.178.208.82/cgi/PF_Store/...hispage&thispage=ECK6.html&ORDER_ID=496242992
Our way is a little simpler. Just by a whole string and tape straws to the bulbs instead of the shrink tube.
We make new ones for each flight intead of using a plug in the bulkplate.....more reliable.