Flashpan

[ELBRAZ]

I decided I'd better do a subscale of the 60 "C" motor cluster Warloc I'm doing for the OKC Triploli Regional Launch at Sayre OK this April. Made a three inch 19 A10-3 motor subscale to try out the rear ejection system and my first flashpan ignition. The wind was a problem but we finally got the bird launched. Flashpan works great! Puff of smoke and the critter was OUT OF THERE! Attaching a picture of the rocket on the messy workbench, cause I pooched the .avi file of the flight.

 

[ELBRAZ]

got to resize the file...
-braz

 

[ELBRAZ]

Finally (maybe), a view of the business end of the critter. Lost a fin when the chute didn't deploy...

 

[Ryan S.]

wow that is cool, and man is that alot of motors

 

[marvSRG]

Sweeeeeeeet

 

[Adam Selene]

Originally posted by ELBRAZ
Finally (maybe), a view of the business end of the critter. Lost a fin when the chute didn't deploy...

that is a lot of motors. very cool!
how do you use a flashpan anyway?

 

[Ryan S.]

did you glue those motors in? or make alot of little motor tubeS?

essentially flashpan is a bunch of BP under the rocket, when it ignites it flares up into all the motors. I will let ELBRAZ explain though, since he did it with such great results

 

[tbzep]

The trick is to have the right amount of BP in the pan to be able to get all the motors to ignite without ruining the paint job on the bottom third of your rocket.

tim

 

[Adam Selene]

care to share any hints about how one goes about doing that?

 

[marvSRG]

Usually if you just line the bottom of the pan with one layer of BP you will be fine. Another good method is taking aluminum foil, and shaping it to the motor cluster and lining it with a thin layer of BP. Then you just tape this directly to the motors. It definately takes away from the flash effect as most of it only flashes under the rocket, and not under and up around it, but it is very effective.

Hope it helps...

 

[ELBRAZ]

Ryan - I glued the motors together and cut 3/16" foam centering rings to hold the whole mess in a 3" coupler. I don't want to trust even 60 Motors to pressurise the full scale Warloc body, so I made a rear ejection system that drags out a drogue chute to deploy the main.
I launched in the usual Oklahoma conditions, 10-15 mph winds, so getting the bp to stay in the pan was a trick. I'll make a wind-shade for the full scale, you betcha.
-Braz


bonus pic: 3-stage toilet paper roll rocket.
(I've got some good scale pics, whats the best way to compress em?)

 

[tbzep]

Originally posted by Adam Selene
care to share any hints about how one goes about doing that?

I'm probably not the one to answer that... I like lots of smoke and fire, so that's the way I rigged the only flash pan launches I've done. I built a disposable cluster rocket and burned the thing pretty good but it flew just fine and looked great coming out of the smoke and fire on launch. I finally lost the rocket and haven't done any more flash pan ignition flights since.

tim

 

[Adam Selene]

nice tease!
that sounds like at least some cool pics but how di d you do it?

 

[tbzep]

Pretty much like marvSRG said. Use something flat underneath the rocket that you can spread a thin layer of BP over. It's not terribly important how close you have the pan to the nozzles, but I would keep it within an inch or three. I've never experimented on how far away it can be, so YMMV.

Use your normal launch system to ignite the powder and it will flash up into the open motor nozzles. If you use too much it can knock the rocket up the launch rod a few inches before the motors come up to thrust and it will scorch the rocket. It looks really cool, like I mentioned before, but don't fool with trying get a perfect paint job if you plan on using this method of ignition.

tim

 

[Adam Selene]

how thin is a thin layer of black powder?

 

[marvSRG]

An even layer about 1mm thick across the pan (or at least the area under the cluster) should do. However, for more dramatic effect, more can be used. Doing this, however, does begin to exchange the looks of the rocket with the looks of the launch. Choose what you want. I've done both. I built a really crappy 13 motor cluster rocket only only intended for use once (it was recoverable but just built for a demo) and I used plenty of BP on that one...more for effect and the fact that 13 motors is much more than usual. It worked perfectly and worked without a problem. Well, for ignition, anyways. In building it I left gaps in the motor mount and the flashpan popped the nose cone. Oops...it was still cool. For my nicer rockets such as my 11 motor to 1 motor two stager, or my 1-19 motor capable Wonderboy, I have been a bit more sparing with BP. Especially on the Wonderboy- it's a nice rocket, and yet, I've still scarred the paint a bit. The two stager wasn't fully painted, so I just used the right amount of BP not to damage it. Paint wasn't an issue there. So, back to your question (man I ramble a lot) 1mm spread across the board and covering the cluster area should be fine, but for increased effect (and sacrificing paint) more can be used. And use your head...don't be rediculous and put a 1-2cm thick layer in there--that's insane and threatening to the rocket, and therefore bystanders. But a layer of a few millimeters may mess up paint, but make a better looking launch. Ok...I'm done! Check out the pictures at my site and at www.geocities.com/mcrocketprojects under the joint projects section.

Hope it helps

 

[Adam Selene]

cool!
thanks marv! now i get it!
btw- where is weddington? i'm in calabash right now. will you be at TRF 2004?

 

[marvSRG]

Great! Glad I could help. Weddington's not near Calabash...which, if my memory serves me right is near the NC/SC border. I'm outside of Charlotte...Union County. Near Monroe.

Glad I could be of some help.

 

[ELBRAZ]

I've prepped the motors for the clone WarLoc. 60 C6-5's built into a 7.5 inch coupler tube for a rear-ejection system.

 

[powderburner]

You are officially crazy.

Keep us posted on how well this works!

 

[wwattles]

So lemme get this straight... you're going to have 60 BP motor casings all falling from the sky at once from the rear ejection? Or do you plan to have a single casing-holder free falling??? I'd like a heads up on that launch, so I can be in my car and driving very far away from the drop zone!

WW

 

[ELBRAZ]

See that little hole in the middle of the cluster? That's where the half inch forged eyebolt goes. The recovery bridle is attached to that. When the 60 ejection charges wake up and the whole module goes south, it will deploy a 24" square drogue that will extract the five foot main chute. Probably.

 

[ELBRAZ]

Since I finally figured where the re-size funtion was, here's a post-flight pic of the 19 motor bird.

 

[marvSRG]

Awesome, awesome, awesome!!! Can't wait to see and hear the flight results of this one!!! Good luck, dude! And PLEEEEAAAAAASE take pics.

Great job.

 

[ELBRAZ]

Here's the airframe for the clone Warloc, 7.5 inch concrete form and 1/2 inch foamboard fins with balsa leading edges and basswood trailing edges and caps. Filets are going on today, and the fin roots get some glassing tomorrow.

 

[ELBRAZ]

...and here is the nosecone. It's made of carbon prepreg by Larry Ortega, aka AKAZILLA on the forums. This was a test run for the tooling, his current ones don't need any filler and are beautifully gel-coated. Dang strong since they are bagged and cured at about 250 degrees. It can be real handy living down the street from a glass and composite master.

 

[ELBRAZ]

Here's the full size 60 motor Warloc clone. Thank goodness the picture is low res, cause I had to hurry. The glass on the fin roots and around the end of the tube look like cake-frosting, but it will fly(I think). I had trouble peeling the inside of the tube properly, so I put a bulkhead in with one inch finishing nails, about ten of them through the body tube. Sealed the rim with Gorilla glue. The bulkhead is only there to keep the 'chute and recovery bridle up front, so it should be OK. Fins are framed half-inch foam project board. I love that stuff, you can make nearly anything out of it. I take it to the OKC Tripoli regional at Sayre, OK this Saturday. If you in the area and have a Warloc, bring it to the dragrace. Should have seven or eight flying on anything from J350's on up.

 

[marvSRG]

Cooooool! Awesome, bro! Pleeeeeaaaaase take and post pics!

 

[dvldrmmr]

60?! And I thought 19 was alot. You're crazy! I'd think it'd be hard to get them all to light at the same time, but with the flashpan method it'd probably work, never tried it though. I think you win the "Over-the-top" rocket award, at least in my book. Awesome rockets - keep it up...

dvldrmmr

 

[ELBRAZ]

The cluster flew at the second annual Sayre Shootout this weekend. 49 out of 60 motors ignited, and the flight was successful. I'm working on a failure analysis for the ignition problem, but I think the bird was too close to the flashpan. Tinker Hruby, famed photog, got the lift-off pic.
thanks, Tinker!