Best way to attach shock cord wire?

[grimlock3000]

I have Estes Big Daddy kit that I am going to start building tonight. After reading some reviews and feedback on the kit, I picked up some picture hanging wire to replace the shock cord that mounts on the engine centering rings (see stock attachment method here, thanks shockwaveriderz: https://www.geocities.com/sandhawk.geo/Pics/2162-4.gif). I am sure the picture wire will hold up much better than the shock cord since it is that close the ejection charge. I am going to attach the stock shock cord at the end of the wire.

Should I use the same method to mount the wire to the ring and use some epoxy to reinforce it? Or is there a better way to use mouth the wire to the rocket?

 

[shinbone]

With mine, I ran the wire through a hole in the fore centering ring and "tied" the wire around the mm tube, then epoxied it in place. I ran the wire to the end of the BT, then made a loop in it to which the cord was attached. Worked real well, though the wire is much stiffer than kevlar.

 

[grimlock3000]

I could not find Kevlar cord anywhere around here, so I went with the picture wire for now. Once I order some more stuff rocket online, I am going to get some Kevlar cord and use it in all of my kits from now on. I am thinking the wire will not be an issue in the large body tube, but I would not want to try cramming the picture wire into a smaller body tube at any point.

I have been unable to find cellulose insulation as well. I am going to have to use a whole bunch of recovery wadding for each flight if I can not come up with something else to use with the Big Daddy.

Anyway, I am really excited to finish and fly this Big Daddy, it will be my first D powered launch. I launched my Baby Bertha on two C flights earlier this week, and I was like "WOW!" So this D launch will be something special. One good thing about being a newb is that I am very easily impressed (for now)

 

[rocketkid88]

One good thing about being a newb is that I am very easily impressed (for now)

yep... just wait till you see your first mpr/hpr launches the first time i saw a mpr rocket was a G35... i had never seed a composit motor fire b4... did i jump

Also the D12s are nice, but make sure you don't put hte engine block in for the D12 length... either just leave the engine block out and use friction or put it up another inch (i'm not sure if there is room for this in the stock tube tho) so you can get an E9 in there.... i *love* the long burn of an E9!

 

[grimlock3000]

At some point in the future I am going to pick up a Apogee Aspire and use a G80 to try to go supersonic. I need to upgrade my other launch equipment as well, but it is definitely going to happen

 

[shinbone]

Cellulose insulation should be available at any of the big home improvement stores like Lowe's and Home Depot.
I bought a bale o' barf three years ago and have hardly made a dent in it. Compared to standard TP wadding, it's a huge bargain, particularly when flying larger diameter birds like the Daddy.
And you're right, I had no problem using picture hanging wire, but I wouldn't try it in a rocket much smaller in diameter.
I modified my second Big Daddy to take the Estes E motor, and had some real nice flights 'til she drifted away. Spill hole recommended!

 

[grimlock3000]

The local home improvement places do not have the cellulose insulation. Might be some sort of local regulation, or the Home Depots are weird

 

[grimlock3000]

I finished building the Big Daddy, I tied the picture wire around the motor mount and epoxied it there, it is never coming loose now. Then I ran the wire out of the body tube a couple inches and made a loop, which I also epoxied. I attached the stock shock cord to the end of the loop. I do wish there was a bit more space in the body tube between the motor mount and the nose cose though.

I kept looking for cellulose insulation at some hardware stores. I got a response of "No one around here sells it, and we can not order it" DOH!

 

[Fore Check]

To get mor room in your Big Daddy, you can try the following:

Trim out the bottom of the shoulder of the nose cone substantially so that you can access the interior of the nose cone for storage space.

Pack most of the shock cord up in the "tip" of the nose cone, and then put your parachute in the nose cone after the shock cord.

At ejection, with the shock cord up there behind the parachute, it will pull the chute out and it really does work! It also places more weight to the tip of the rocket, further enhancing stability.

 

[grimlock3000]

How do you attach the shock cord to the nose cone after you cut the bottom off it? More epoxy?

 

[Karl]

If you didnt cut the bottom off , this is the way I did it .
Thread the shock-cord through the 'L' shape hole in the NC , loop it , (Not tie it) , And CA the shock cord to the peice of shock cord . Its hard to explain , Ill post a piccy for ya'!

I launched my Big Daddy on Saturday and I've got fed up of having to use a 12" 'chute in it because the 24" wouldn't fit! The reason it doesn't fit is because the shoulder of the NC sits on it and wont go all the way down. So I thought about cutting the shoulder to leave a 2-3" shoulder instead , and adding a ply wood bulkhead , with a Screw-Eye to tie the shock cord to
In fact im going to and do this right now
-Karl

 

[kenobi65]

Originally posted by grimlock3000
The local home improvement places do not have the cellulose insulation. Might be some sort of local regulation, or the Home Depots are weird

If you can't find it there, you can usually find someone selling it in smaller bags on eBay for a couple of bucks. That's where I bought mine, as a couple of one-gallon bags of the stuff is probably approaching a lifetime supply for me....

 

[Fore Check]

Originally posted by grimlock3000
How do you attach the shock cord to the nose cone after you cut the bottom off it? More epoxy?

I'm sorry - should have been more clear. Only trim off the bottom *below* or *at the bottom of* the shoulder of the cone. This leaves the portion of the shoulder with the loop that you attach the shock cord to normally. You attach the shock cord to the nose cone loop normally; you just pack it differently (inside the tip of the cone, rather than in the airframe.)

 

[Karl]

The pictures wont send , everytime I goto send a pic' it says 'This page cannot be displayed' :S
-Karl

 

[grimlock3000]

What exactly is the shoulder of the nose cone? Is that the area where the cone stops going straight along the body tube and angles in? I am fairly certain I know what to do now, but it is a big nose cone to be screwing up if I do the wrong thing. And a big rocket to have the chute deployment fail so I want to get this right

Anyone feel free to email a pic to me at [email protected] if you are having trouble with the forum.

 

[Karl]

Right the shoulder is the part what slides into the Bodytube to keep it in place . Ill send you some more pictures as I am going to cut my shoulder and add the bulkhead right now
Cya l8r
-Karl

 

[Karl]

Here we go :

https://rocketrygallery.tripod.com/

 

[grimlock3000]

Well that makes a lot of sense now, thanks I lack the power tools required to really do it the way you did, but if I find something good to use at the bulkhead I might try it.

I may go with Fore Check's suggestion and cut enough off the bottom to be able to stuff the parachute up into the nose cone.
If I understand it correctly, I would be cutting off the "D"-shaped area at the bottom of the nose cose, everything cut would be below the eyelet used for shock cord attachment.

 

[Karl]

Yep it's the 'D' Shaped part that you should be cutting away . Remember to paint your bulkhead in Varnish , as any damp would make the wood swell ,widen the nosecone , and it resulting in your nosecone not fitting. You dont need the power-tools to do that . You just need some wood , a stanley knife , and a steady hand , then just sand by hand till it fits!
-Karl

 

[grimlock3000]

*newb mode on*

When the ejection happens, does ejection charge smack the nose cone off, or does the increase in air pressurse blow off the nose cone? Is the noce cone method prone to fail, or is it OK as long as you pack the cord in FIRST so it pulls out the shoot? One of days I am going to put a rocket in a vise and set off the engine to check out everything up close.

*newb off*

 

[grimlock3000]

Would it also be a good idea to attach the parachute a few inches down from the nose cone on the shock cord? Like so...

[body tube] cord-cord-cord-cord-cord-cord-cord-cord [parachute loop] cord-cord-cord [nose cone]

 

[Karl]

Well ejection is basicly a lump of Gunpowder that gets ignited when the Delay eliment ( Smoke ) has burnt away . The ejection is ignited and a ball of flame shoots forward (Thats why you need wadding) , and increases pressure , the flame also touches the bottom of the nosecone , and escapes when the nosecone is realeased.
Heres the way you should 'prep' your rocket for flight .

Add the right amount of wadding needed for the dia of the rocket your using , and prod it all the way down the bodytube so it sits on the mmt.

Attach your 'chute to the shock-cord using a slip-knot. Make sure all the shrouds at attached.

Lightly fold your 'chute so it will fit in the BT .

When its folded , lightly wrap the shrouds around the 'chute.

Place the 'chute into the Bodytube , and make sure it's not to tight.

Place the nosecone in it's place , and off you go!

-Karl

 

[grimlock3000]

I actually thought the ejection charge was a "cap" on the gunpowder that shot forward through the rocket, so I just learned something good there

How many sheets of wadding should I use in the Big Daddy? 15?

 

[Karl]

lol , you could do that , but the way I like to do it is to tie it threw the eye let in the nosecone , or a couple of inches down the shock cord. What you want to avoid is , tie'ing the 'chute so that the nosecone hangs around the fin area , this could damage fins.
-Karl

 

[Karl]

Erm , It says use 5 but it ISN'T right! I used 10 and the 'chute was still slightly damaged , so 11 or 12 will do just fine

No it isn't a cap , the grey cap is a clay retainer that keeps it in place , and to stop it getting damaged , it is so thin that when the ejection ignites , the cap smashes into tiny bits (You might find these in the bottom of your bodytube , sitting on the centering rings)
-Karl

 

[grimlock3000]

When I read the insturctions that said to use 5 sheets of wadding, I assumed it was talking about some huge D+ sheets of recovery wadding I had not seen before. I spend an awful lot of time looking for where to get the bigger sheets of recovery wadding before realizing it did not exist

Should I lay in the sheets somewhat flat, or crumple them into loose balls?

 

[Karl]

What I do is , cover the top of the mmt with 2 sheets of flight wadding , then put 8 or so slightly crumpled balls on top. Also when you fold your 'chute , before you put it in place , put another sheet at the bottom of the 'chute for extra 'insurance' that it wont get damaged. You might also want to lightly dust your 'chute with talc , so that you have a 99.9% chance of it opening fully.
-Karl

 

[Fore Check]

Originally posted by grimlock3000
Well that makes a lot of sense now, thanks I lack the power tools required to really do it the way you did, but if I find something good to use at the bulkhead I might try it.

I may go with Fore Check's suggestion and cut enough off the bottom to be able to stuff the parachute up into the nose cone.
If I understand it correctly, I would be cutting off the "D"-shaped area at the bottom of the nose cose, everything cut would be below the eyelet used for shock cord attachment.

You are correct, grimlock - that D-shaped area *below* the regular attachment loop is what gets trimmed away. Essentially, your just making that hole that's already in the bottom of the nose cone a lot bigger, so you can easily access the inside of the nose cone for storage space.

Make sure you roll your parachute into a somewhat cylindrical shape, and don't pack it up "above" the lip that remains on the inside of the cone (the lip that is there to make space for the regular attachment ring.)

Just put the chute inside of the shoulder and poking up into the cone.

Go ahead and trim the cone as we are discussing here (it won't hurt anything if you decide not to pack your chute this way in the end) and then practice packing the shock cord up in the tip of the cone, followed by the chute. Insert the cone into your rocket, and then pull it out quickly to satisfy yourself that the chute will deploy.

As far as where to attach the chute, I recommend first attaching the chute to swivel clip (I get mine in the fishing department at Wal-Mart, cheap) and then "clipping" the chute to the rocket. Then, you can experiment with your attachment point. For most rockets, I hook the chute to nose cone at the same point as the shock cord (that loop or eyelet.) In this modified stowing / deployment method, you might try tying a loop in your cord at a location similar to the one you describe a few posts above this one to ensure that the chute gets pulled out of the nose cone when the shock cord reaches full extension.

Just make sure that you don't leave so much distance or length of shock cord between the chute attachment point and the nose cone itself such that when you grab the shock cord at the attachment point and then lift the rocket and nose cone (with the nose cone now hanging downward towards the rocket) that the nose cone *hits* or touches the rocket airframe when doing this.

 

[grimlock3000]

Ok, I finally got around to the Big Daddy last night. First, I tried going with the method of having the chute tucked into the nose cose. In my experimenting around, I could not get the chute to reliably pull out of the cone. I was having visions of watching another rocket fall from altitude with no chute. Then I just went for broke and cut off the bottom section of the nose cone to go with a bulkhead setup.

Once I had the cone cut open, I epoxied two nickels all the way in the front of the nose cose. Thise should help with stability, or at least I hope it will. The two nickels and epoxy weigh just about half an ounce. Then I epoxied six small pieces of balsa on the inside of the nose cone, right where the shoulder meets the cone, these were put here to make sure the bulkhead sits flat in the cone. While that was hardening, I cut two circles from 1/8 inch balsa and glued them together with the wood grain crossed so it would be stronger. I drilled holes in the balsa, and put a zip tie through the bulkhead as the chute attachment point and epoxied that as well. After some quick sanding, the bulkhead fit right in the nose cone and sat level thanks to the balsa bits inside the cone. I epoxied around the outer edge of the bulkhead to hold it to the nose cone.

Now I have MUCH more room inside the body tube! Thanks for all the help, I feel much better about flying this rocket now

 

[astrowolf67]

Grim, one thing when you go to the home improvement stores looking for cellulose wadding, ask for "blow insulation". They will know what that is.

Also, when I use sheet wadding on my Big Daddy, I crumple and stuff one sheet into the upper end of the motor mount, then lay a couple of sheets in flat, then about 8 very loosely crupmled sheets, and I also wrap the chute in a sheet of it's own. One other suggestion I've heard of, but not tried, is using something like an aluminum foil baking cup to hold the bulk of the shock cord, and chute.