Flash Pan Ignition of 2nd Stage Cluster

[lakeroadster]

Has anybody done a flash pan style ignition of the second stage of a rocket?

This is a 5 cluster motor that has a single motor, with 4 satelite motors. Link to build thread. My thought is the 1st stage center booster motor would ignite the second stage motors, via a staging tube that leads to the flash pan under the second stage motors.

There would be vent holes around the perimeter of the rocket, or maybe even screened openings, to try to minimize the pressure increase when the BP in the pan ignites.

I initially was just going to gap stage each motor via the 1st stage corresponding motor, but since the 1st stage motors will all vary in burn time, I figure that's a bad plan.

Thoughts?

Suggestions?

Are you questioning my sanity?

Thanks!

 

[shockie]

Go for it!

 

[waltr]

Go for it!

And get a Video.

 

[Daddyisabar]

The flash pan build would be totally tubular. High skill level fabricating thin metal pan and nozzle tubes. Listening to tubular bells after being possessed by the idea.

 

[kuririn]

Haven't done it, but others (in Europe) have had success firing clusters with Klima tape match and igniter sticks. Instead of electrical ignition of the tape match you would use the hot gas from the booster. Maybe a piece of fuse sticking into the tape match? Availability in the US is a question mark.
Perhaps you can make your own with gunpowder, tape, and short sections of fast burning fuse. Seems like immobilizing the powder in tape would be preferable to having it loose in a flashpan.
(Just musing here, don't know if NAR rules are being violated, especially the fuse part).
https://www.modelrockets.co.uk/shop...e-match-reliable-cluster-ignition-p-3401.htmlhttps://www.modelrockets.co.uk/shop...er-sticks-for-staging-or-clusters-p-3400.htmlPS Multiple ground tests would seem to be in order.

 

[Daddyisabar]

Time to hang out at the Pyro Club! They make awesome home made match tape. Just don't go too far to the dark side making your own BP motors!

 

[teepot]

I have been trying to come up with a way to do composite to composite ignition. I thought fuse. I have some fuse that is .1 to .3 seconds per foot. I'll try it at home first and then see what the club officers think if it works.

 

[kuririn]

The more I think about it, perhaps the tape match isn't needed, just the fuse igniter sticks. Vent holes near the second stage motor nozzles. Maybe just the blowby from 3 or 4 motors could light up all the motors in the second stage. Worth ground testing, IMHO.

 

[heada]

I have been trying to come up with a way to do composite to composite ignition. I thought fuse. I have some fuse that is .1 to .3 seconds per foot. I'll try it at home first and then see what the club officers think if it works.

If you dip the end in a pyrogen, it can light APCP motors. The issue I've run into is coming up with a zero delay APCP motor. There are some SU motors that have short delays of 2 to 3 seconds, but none that are 0 seconds like there are in BP motors.

 

[Daddyisabar]

If you dip the end in a pyrogen, it can light APCP motors. The issue I've run into is coming up with a zero delay APCP motor. There are some SU motors that have short delays of 2 to 3 seconds, but none that are 0 seconds like there are in BP motors.

Unless you drill them to 0 delay. WHAT GOES ON IN VEGAS STAYS IN VEGAS!

 

[heada]

Unless you drill them to 0 delay. WHAT GOES ON IN VEGAS STAYS IN VEGAS!

I've not had much luck drilling past the minimum recommended by the manufacturer. If you have, then good on you but I generally don't want to risk my rocket turning into a pile of burning bits.

 

[Daddyisabar]

I've not had much luck drilling past the minimum recommended by the manufacturer. If you have, then good on you but I generally don't want to risk my rocket turning into a pile of burning bits.

If you can not live with the vision of your rocket as a burning pile of goo, do not press the button!

Cutting delays. Worked ok once down to a very short delay. The next time...burning goo.

 

[teepot]

If you dip the end in a pyrogen, it can light APCP motors. The issue I've run into is coming up with a zero delay APCP motor. There are some SU motors that have short delays of 2 to 3 seconds, but none that are 0 seconds like there are in BP motors.

In the fantasy motor thread I wished for a composite 0 delay booster motor. Aerotech are you listening.

 

[Neutronium95]

In the fantasy motor thread I wished for a composite 0 delay booster motor. Aerotech are you listening.

That's not really feasible. The delay grain on a composite motor has to contain the pressure throughout the burn. If if was thin enough to burn through at the same time as motor burnout, it would blow through before that. The shortest delays that I've heard of working in composite motors are on the order of 3-4 seconds.

Besides, what's in it for Aerotech? You can't light a composite motor properly with an ejection charge or the burst of fire from a -0 motor, so even if they made these motors, they could only be used with Estes motors.

If you want to stage composite motors, electronics are by far the best option. I've heard of people using fuse, but with the availability and capabilities of modern rocket avionics, I don't think there's any reason to use anything else.

 

[lakeroadster]

Besides, what's in it for Aerotech?

Selling more motors.

You can't light a composite motor properly with an ejection charge or the burst of fire from a -0 motor, so even if they made these motors, they could only be used with Estes motors.

But you can use a fuse dipped in pyrogen....... according to what @heada just posted...

If you dip the end in a pyrogen, it can light APCP motors.

 

[heada]

Selling more motors.



But you can use a fuse dipped in pyrogen....... according to what @heada just posted...

Pyrogen dipped fast paper fuse can ignite APCP motors but it is moot since there are no 0 delay APCP motors and no real feasible option to have them. Electronics are the best way to stage APCP motors, hands down.

 

[beeblebrox]

Unless you drill them to 0 delay. WHAT GOES ON IN VEGAS STAYS IN VEGAS!

You can't do that, they will blow thru early... AeroTech extensively tested that years ago and it was deemed to be too unreliable. The only exception is with end burners like F10's and E6's Those will work. Even AeroTech didn't stay in Vegas...lol

 

[Rocketjunkie]

I see you plan on using BP motors. Get some very fast fuse https://www.skylighter.com/collections/firework-fuse/products/quick-fuse-white-gn1207 Check the nozzles of the motors and make sure you can see the BP grain and it's not covered with clay. Put in a few grains of BP and then a piece of fuse about 1" long. Then flash pan the fuses. An alternative is the MJG BP motor starters. These are small ematches that fit all the Estes motors and your altimeter should be able to fire them directly. They will not light composites without dipping and probably won't fit the nozzle of Q-jets.

 

[Daddyisabar]

You can't do that, they will blow thru early... AeroTech extensively tested that years ago and it was deemed to be too unreliable. The only exception is with end burners like F10's and E6's Those will work. Even AeroTech didn't stay in Vegas...lol

Like I replied it worked once and not the second time. 50% reliable! It was years ago flying the infamous Sunward Umbrella. After many flights on D12 3 I was getting bored and the high power guys were always annoyed at the mere sight of the Drag Oppressed Rocket Kit (DORK). I had just bought a used 24/40 case and was still a relitive reload neophyte. I decided to experiment with drilling F12-5 Black delays down with an Xacto knife. As I remember No drilling tools at that time. The first flight was awesome, the HiPo guys liked it; hey Mikey, they liked it!

The second flight was a few weeks later and it went up, 30 feet off the rod, then ejected prematurely and became a roman candel that landed next to the pad, slowly burning and smoking away. Damage was not that bad on the tough and Awesome Canadian kit, just burning up the top of the body tube. The god awful 3 fold shock cord mount was hibachied. The HiPo guys and RSO were appalled, but still had a good laugh, as my extreme delay drilling overtures were brutally rejected.

Repaired, the ugly ducking was back at the next launch on D12 3 to again annoy the tender sensibilities of the HiPo crowd. Now after 100's of reloads, it stands as my one failure, so embarrassing and shameful. Shame, shame shame! The hole in the forward closure was twice the size but it still worked. But at least I went Big and did not go home! HIPO RULES! VEGAS RULES!

 

[teepot]

One rocket I built early has a booster with 3 29mm mmt's in a 4" tube. The sustainer has a 29mm mmt in a 2.6" BT. When I built it, this is before I started weighing things before they were built. I planned on 3 F15-0's. Unfortunately 3 F15's won't get it of the ground. So I thought 3 G78-4's. ThrustCurve says almost 900' in 8 seconds. But, a big but. How to light the next motor. That's where the fuse comes in .1-.3 seconds per foot. Up the nozzle of the sustainer. When I built this I hadn't considered using electronics. I hadn't tried DD. I built it about 3 years ago. I have a lot of my early rockets that probably couldn't fly. I was ignorant, er, uneducated. Now I wouldn't build those kind of things. OOps. Port-O-Potty rocket. Maybe I still do build those kind of rockets.

I've been here 31 years. No place like Vegas, Baby. Fly in here at night some time.

Dave

 

[lakeroadster]

"The god awful 3 fold shock cord mount was hibachied."

That line right there is worth the price of a yearly membership here...

 

[Daddyisabar]

That line right there is worth the price of a yearly membership here...

I really do love the old school three fold mounts for low power and have had great success with them. Only once have I had a three fold mount pull off on a mid power rocket with craft tubing. I have burned through motor mounted kevlar several times after many flights. I like bashing 3 folds because it is cool with the in crowd, but deep down I love them and keep using them. Sometimes I extol the virtues of the 3 fold to throw a wrench into the bullet proofing narrative and chide the haters.

 

[Rocketjunkie]

Even for high power cardboard rockets, I use a variant of the tri-fold mount. A piece of tubular nylon is glued to the inside of the tube. You can see the puddle of epoxy in the second pic.Fiberglass rockets get the Kevlar strap on the motor mount or stainless cable around the motor mount.

 

[GlenP]

I see you plan on using BP motors. Get some very fast fuse https://www.skylighter.com/collections/firework-fuse/products/quick-fuse-white-gn1207 Check the nozzles of the motors and make sure you can see the BP grain and it's not covered with clay. Put in a few grains of BP and then a piece of fuse about 1" long. Then flash pan the fuses. An alternative is the MJG BP motor starters. These are small ematches that fit all the Estes motors and your altimeter should be able to fire them directly. They will not light composites without dipping and probably won't fit the nozzle of Q-jets.

Could that type of cluster fuse be braided together into a single cord fuse to run along the entire gap in between the sustainer nozzles and boosters, and then split again at the booster side into each ejection/ignition source, instead of a flash pan? That would be more like a flash cord fuse, instead of a pan, I guess. Is that feasible at all? Might hold together better in a spin-stablized rocket, maybe.

 

[Steve Shannon]

Has anybody done a flash pan style ignition of the second stage of a rocket?

This is a 5 cluster motor that has a single motor, with 4 satelite motors. Link to build thread. My thought is the 1st stage center booster motor would ignite the second stage motors, via a staging tube that leads to the flash pan under the second stage motors.

There would be vent holes around the perimeter of the rocket, or maybe even screened openings, to try to minimize the pressure increase when the BP in the pan ignites.

I initially was just going to gap stage each motor via the 1st stage corresponding motor, but since the 1st stage motors will all vary in burn time, I figure that's a bad plan.

Thoughts?

Suggestions?

Are you questioning my sanity?

Thanks!

View attachment 548467

One really important characteristic of flash pan ignition is that it’s completely uncontained. Hot particles and possibly infrared energy are directed upwards toward the bottoms of the motors that you want to ignite, but, there’s no containment.
In your design, the pan and the powder must be contained. I think it could act like a big firecracker.
I’d like to suggest ground testing the interstage coupler with the flash pan. I’d love to see a video.

 

[lakeroadster]

Gentlemen the use of a fast burning fuse to ignite the 2nd stage motors sounds like a more reliable one for this design.

But the flash pan idea sure is intriguing. Thanks to everyone for their thoughts and suggestions.

 

[Daddyisabar]

An interal staging - spider tube flash pan would require an experienced master to build and deploy. Getting the charge and gas flow containment-venting just right to each motor. Easier to use a spider of quick fuse / tape like the pyro guys employ. Spinning the rocket would make things worse. That might require some sort of pan or shield to tape the spider fuse arms to keep them in place and protect the first stage from second stage ignition hibachi.

 

[Daddyisabar]

Gentlemen the use of a fast burning fuse to ignite the 2nd stage motors sounds like a more reliable one for this design.

But the flash pan idea sure is intriguing. Thanks to everyone for their thoughts and suggestions.

Make it really fast because you need the second stage to ignite with enough momentum to keep her going straight up. Need it to ignite at a decent hight off the rod/rail. No nasty oscillations! Big thrust on first stage, just like the real McCoy! You don't watch NASA on TV...you live it!

 

[shockie]

I wonder if the ejection charge(s) from the 1st stage booster would ignite loose BP in a internal spider that sits like an interstage adapter between the 1st and second stages would work?

Videos that I've seen in super slow mo show a pretty pronounced flame front that shoots out.

 

[heada]

I wonder if the ejection charge(s) from the 1st stage booster would ignite loose BP in a internal spider that sits like an interstage adapter between the 1st and second stages would work?

Videos that I've seen in super slow mo show a pretty pronounced flame front that shoots out.

I think the concern is that with the induced spin, any loose BP would be forced towards the outside and may not be in line with either the flame from the booster motor or in line with the sustainer motors. The need is to pass flame from the central booster motor to all 5 sustainer motors nearly instantly and in a way that isn't impacted by the induced spin. I can only think of 2 ways that would do it reliably; 1) electronics (absolutely best way) and 2) fast paper fuse.