Firebird

[Neil]

Well, I got designing on rsim again... I gotta stop doing this... Im gonna make myself go broke if I keep designing these things!


Well, as usual, I designed the rocket, and fell in love with it. Now I just *HAVE* to build it... Im sure yall know what I mean by that

Its going to have a PML nosecone, PML 4" quantum tubing, 54MM motor mount, and all that good stuff. Weight is about 4# according to rsim. I have a few questions about working with PML Quantum Tubing. I have used it several times in kits, but I have never tried to slot it before... Will a standard cut-off ring on a Dremmel tool work on QT? thats what we use on our mailing tubes nowadays, and it works great on them. Will it do QT too? Does it give off any funny dust or react to the heat from the dremmel too funny? I know this stuff cant take transonic speeds or really high temps from motors, but will the Dremmel do anything funny to it if I am just making light passes?

I plan on using quarter inch plywood on this bird... Unless... Can you cut G10 with a jigsaw? I wouldent think so... Can you? If you could, I might as well use G10 fins... If they arnt too expensive...

I would like to keep this under $60. Thec omponents (shockcord, nosecone, launch lugs and body tube) come to about $53, plus shipping would be about $60. So thats just about perfect. I dont want a piston system, though. I think ill order all this from Magnum and buy a heatshield as well.

Heres a .rkt of the rocket... What do you think? I dont have the $$ to do this right now (I still owe my mom $30 from the shipping charges of my Polecat Nike Smoke), but maybe in a month or two, I will be able to buy the parts.


(OBTW... I know its a little short, but I tried it with the 48" tube and it didnt look right. I guess this ones gonna be stubby, folks )

 

[Neil]

Its just 3" shorter than the Quarter Scale Patriot, BTW. With a bigger MMT, of course

 

[daveyfire]

Looks good. Yes, you can cut G10 with a jigsaw, it's how I make G10 fins for my rockets! Wait until you get the Nike built and all your other projects finished, and then dive right in.

One suggestion I have is to make the noseweight system adjustable, using allthread and cast lead shot (or washers). That way, you can fly higher on smaller motors, but if you ever get the itch to put in a K700W, you can...

 

[Neil]

How exactly does that work? Ive never quite figured that out... I dont think ill want to fly it on anything too small (I got all these Hs and Is sitting around, I might as well burn the things... ), so I think ill just stick with what I know, and put a pound in there, and if it needs more i can give it more, if it dont need more, I can leave it alone.

But, if its easy to do it another way, I might as well learn how...

By the time I have $60, I will have built, painted, and maybe even flown my Nike Smoke I dont make money that fast...

 

[daveyfire]

Here's what I do:

1. Cut off the base of the nose cone, so it's nice and straight across the bottom and you have a full-diameter hole in it.

2. Scrape up the inside of the tip of the nose cone a lot using some sort of sanding deelie. 60 grit sandpaper works well. This is important so the nose cone holds together. Also, sand around the inside lip of the shoulder of the cone.

3. Take a piece of allthread (I use 1/4-20 as a standard on rockets down to 3" diameter) and thread a tee-nut, or a nut and a washer, onto the end.

4. Cut two bulkheads to fit inside the shoulder of the nose cone. These should be a good slip fit into the base. Pick a bulkhead and cut a reasonably large hole in it (this doesn't have to be precise, but IMHO the annulus left should be no more than 1/2").

5. Epoxy the brand shiny new ring into the base of the nose cone at a depth of the thickness of the first bulkhead plus about 1/8" (this doesn't have to be exact, just so you're comfy with it -- but it should be level!).

6. Drill a hole in the center of the other (solid) bulkhead to fit your allthread.

7. Place the end of the all-thread with the tee nut on it into the tip of the nose cone. Pour a bunch of epoxy around it to cover the nut and the allthread to a depth of about 1/4". Get a bunch of epoxy in there.

8. Slide the drilled bulkhead onto the allthread and seat it on the preglued ring. If the epoxy has a tendency to exotherm, put the nose cone in a bucket of water.

9. Wait for the epoxy to cure.


It sounds really complicated, but it's very logical and it's easier than it sounds. Basically you are anchoring a piece of allthread in the tip of the nose cone and putting a removable bulkplate on the other end. That way, you have access to the inside of the cone for adjusting noseweight, mounting trackers, etc. Slide the weights onto the allthread and back them up with a nut and washer.

A nifty tip I learned was that if you grease the end of the allthread before epoxying it, you can unscrew it after you're done. That way, it's easier to load the noseweight onto the allthread with a nut to hold it in placce (you don't have to thread it on deep in the nose cone tip).

I'll attach a drawing to (hopefully) help out a little bit.

 

[lalligood]

Neil,

Although I have never slotted QT, I have cut it before (had to cut a damaged section off my Phobos once) with a hacksaw. Surprisingly it cuts *very* easily. It may burr up like other plastics typically do when cutting them with a Dremel cutting wheel, but it's nothing a little sanding wouldn't take care of! Ultimately, just be careful because the Dremel will make short work of your slots.

And most importantly: MEASURE TWICE; CUT ONCE

 

[Neil]

Interesting system... I might have to try that! I will have to try that!

But... How do you cut the end off? Dremmel tool (man, these things are very usefull, aint they? )?

So... now I just gotta make me some more money...

 

[BlueNinja]

I would use a hacksaw.

 

[Steward]

Originally posted by daveyfire

It sounds really complicated, but it's very logical and it's easier than it sounds.

A question for Daveyfire....(or anyone else...)

I guess depending on the size of the nosecone... and the availability of the materials needed...

Could this be done using a long(er) eyebolt? That way you could use the eye at the tail of the cone to attach the recovery line...???

Just wondering...out loud...!!!

Steward

 

[lalligood]

I apologize...I don't think I was very clear in my previous post. What I meant to say is that QT is surprisingly soft to cut (as I learned with cutting it with a hacksaw by hand). I've never slotted QT but I would think that a Dremel (it has my vote for being the most versatile power tool on the planet) would make quick work if you used a cutting wheel.

Slightly OT: If using a Dremel to cut/slot phenolic tubing, I definitely recommend using a reinforced cutting wheel, not a standard cutting wheel--it chews 'em right up!

Whew! And don't forget safety glasses regardless of what material you're cutting with a Dremel <- protective shades

 

[BHP]

Steward asked:

Could this be done using a long(er) eyebolt? That way you could use the eye at the tail of the cone to attach the recovery line...???

Yep - I've done it many times. The key is to really rough up the interior of the NC. I use a 60 g sleeve on a sanding drum for the rotary tool. After having a couple of epoxy 'slugs' fall out (but never on a flight) I make a conscious effort to really score the plastic well to give the epoxy some tooth to hang on to.

All but one of my HPR rockets and several mid-power rockets use this technique. One of my favorite flyers - OSCAR - uses this type of attachment. One highly weathercocked flight deployed the drogue at a high enough speed that it blew apart the Cert 3 SkyAngle drogue 'chute (which they kindly repaired) yet the eye-bolt/plywood bulkhead attached this way held up to the deceleration stress.

I like this method also because it opens up the NC and creates some usable payload space. In fact, last fall Oscar carried a bottle of Crown Royal Whiskey to about 8000' riding on an EX M2000. The whiskey is now gone but it was merrily consumed as the re-dubbed Mach One Whiskey. Check out a video of the flight here:

Whiskey Ride Click on the Oscar M2000 link.

BHP

 

[gerbs4me]

Oscar is a great flying rocket, seen it fly a couple of times, wish I could seen on the EX M2000

The Dremel is an amazing tool, don't know what I'd do w/o it. I used the Dremel to sand the inside of my V2 NC,

I used the pill bottle with weight inside of it, instead of the threaded rod. I'm thinking of making a new NC for "I'm too Sexy for my Cert" since its made of foam I just glued in some BB's inside the foam.