Adding an ejection charge to a D12-0

[BDB]

[Disclaimer: I know that adding an ejection charge to a stock motor like a D12-0 would not be allowed at a NAR launch. I would either fly this under TRA experimental rules or in a private launch and personally assume potential liability.]

I recently built an Estes Ventris and attached two boosters to it that were designed to fall off mid-flight. The mechanism for separation is similar to the Apogee Component's design, where the motor's ejection charge initiates the separation. Consequently, the boosters stay attached to the rocket during the delay portion of their engine's burn--i.e. when loaded with a D12-3, the boosters stay attached to the rocket for an unnecessary 3 seconds.

Can I make a motor with a shorter ejection charge? Has anyone tried adding an ejection charge to a D12-0 or adding a thin delay followed by an ejection charge to effectively create a D12-0.5?

 

[kuririn]

I have flown the Apogee strap on boosters in my Flying Machine using B6-0 motors. The pressure of the burn through gases popping out through the propellant wall is enough to deploy the streamer and nose. You may want to do a static test using a stock D12-0 and see if it is sufficient to pop your laundry in your scratch booster pods.
Edit: PS I would also take precautions against zippering in your booster tubes.

 

[waltr]

I was thinking the same thing, Burn through creates enough pressure.
I have a three motor rocket like your but without detachable pads. Run -0 delay motors and first did not get tight enough friction fit. Both ejected at burn-thru.

 

[James Duffy]

The pressure of the burn through gases popping out through the propellant wall is enough to deploy the streamer and nose.

Can confirm that this is the case. We flew Bumper WAC FAI scale altitude models like this for years with great success.

Be aware that the model does not get too terribly high before the ejection event occurs, and that the event will not be gentle.

 

[cerving]

Just plug the end of the motor with wadding and use electronic ejection.

 

[rharshberger]

Won a shortest duration egg loft event using a D12-0 in a Enerjet Aero-Dart clone (bt 70)...12 seconds from first movement till grounded, chutes popped about 30' or less after take off.

 

[BDB]

We’ll this sounds waaaay easier than I thought….

Thanks!

 

[Steve Shannon]

One thing. Black powder research motors are prohibited at Tripoli launches.

 

[BDB]

Thanks to everyone who suggested just using a zero-delay motor. D12-0 motors in the boosters worked great!

The next phase of this project is to upgrade to AP motors, which means I'm going to probably have to take @cerving 's advice to use electronic ejection. Fortunately, I have a few of his Quantums laying around my rocket workshop.

 

[georgegassaway]

It is allowed to use BP for homemade ejection charges (normally fired electrically), or to add to the existing ejection charge of a motor in order to assure chute ejection of a large volume rocket.

So, given that, MY take is that adding BP directly to a booster motor for the sake of a SAFE ejection is OK.

To NOT add it, and count on the very wimpy pressure of a regular booster motor, is risking safety. One of those "crash caused in the name of Safety" kind of things.

 

[gldknght]

Something else. Estes motors designated with a -0 have no delays. When you look at the top end (opposite the nozzle) you are looking directly at the top of the propellant charge. When that burns through in a single stage rocket, the burning propellant pressurizes the rocket body tube. Often this overpressures the body and causes a disintegration of the rocket. I've personally witnessed this twice, the only two times I've seen a -0 motor used in a single stage rocket.

So merely adding some BP to the top of a -0 motor will not result in a slightly longer delay. No D12-0.5. You must add a "delay element" to prevent the flame front from reaching the added BP. That delay element must be structural enough to contain the pressure from the burning propellant, but burn fast enough to ignite the ejection charge.

 

[georgegassaway]

Something else. Estes motors designated with a -0 have no delays. When you look at the top end (opposite the nozzle) you are looking directly at the top of the propellant charge. When that burns through in a single stage rocket, the burning propellant pressurizes the rocket body tube. Often this overpressures the body and causes a disintegration of the rocket. I've personally witnessed this twice, the only two times I've seen a -0 motor used in a single stage rocket.

If it was a fast-flying model when the booster made the nose come off at maximum speed, then most likely the model broke up from aerodynamic reasons. I have never seen a booster motor have the kind of forward kick that would "disintegrate" a rocket just from a wimpy booster forward poof, as though that would have also made the rocket disintegrate even if it had stuck on the pad or been static fired.

The weak forward "poof" from a booster motor is relatively wimpy compared to a real ejection charge, It should never be expected to act like a real ejection charge. True, a model can be special designed to TRY to use a normal booster motor to kick out a recovery system, but it all has to be very loose, in a limited tube volume, with a very loosely packed chute that may not get blown out anyway (not much to blow it out), inviting other issues.

Again, my take, is add some BP to the top of the booster, to create a real ejection charge. That would be the SAFEST way to fly it (I'm not going to count the risk of loading BP as a safety issue, for the same reason that making up custom BP charges for electronically fired charges is not considered "unsafe", and is allowed. Gotta be careful with BP, always.).

I dunno whoever implied that adding BP to a booster motor would add a delay, that's certainly not true. It all goes off at the same time at burnout, BP or no BP, no delay.

 

[gldknght]

If it was a fast-flying model when the booster made the nose come off at maximum speed, then most likely the model broke up from aerodynamic reasons. I have never seen a booster motor have the kind of forward kick that would "disintegrate" a rocket just from a wimpy booster forward poof, as though that would have also made the rocket disintegrate even if it had stuck on the pad or been static fired.

The weak forward "poof" from a booster motor is relatively wimpy compared to a real ejection charge, It should never be expected to act like a real ejection charge. True, a model can be special designed to TRY to use a normal booster motor to kick out a recovery system, but it all has to be very loose, in a limited tube volume, with a very loosely packed chute that may not get blown out anyway (not much to blow it out), inviting other issues.

Again, my take, is add some BP to the top of the booster, to create a real ejection charge. That would be the SAFEST way to fly it (I'm not going to count the risk of loading BP as a safety issue, for the same reason that making up custom BP charges for electronically fired charges is not considered "unsafe", and is allowed. Gotta be careful with BP, always.).

I dunno whoever implied that adding BP to a booster motor would add a delay, that's certainly not true. It all goes off at the same time at burnout, BP or no BP, no delay.

I can only tell you what I've experienced flying booster motors in a single stage rocket. Did it twice, many years apart, blew up the rockets both times, at motor burn out, never saw the nose come off either rocket.

Never ever had anything like that happen with sustainer motors.

 

[Daddyisabar]

I have added a modicum of BP to the top end of red labled cluster motors many times, topped off with a plug of dog barf. Such practice is clearly indicative of the Dark Arts where one is circumventing established rules in order to fly the rockets they love. Beware of the Dark Side. Only the most vile rocket designs require a 0 delay. Needless amounts of weight or drag resulting from fundamentally poor design, or silly fall away boosters, are at play and are subject to RSO judgment with extreme prejudice! Multi tiered review of Master Jedis is required, not just Top Men wanting to see something interesting or betting on the severity of the upcoming crash. A zero delay required to make your rocket fly safely? Balderdash. Put them on the far far away pad to learn their lesson.

 

[lakeroadster]

[Disclaimer: I know that adding an ejection charge to a stock motor like a D12-0 would not be allowed at a NAR launch. I would either fly this under TRA experimental rules or in a private launch and personally assume potential liability.]

I recently built an Estes Ventris and attached two boosters to it that were designed to fall off mid-flight. The mechanism for separation is similar to the Apogee Component's design, where the motor's ejection charge initiates the separation. Consequently, the boosters stay attached to the rocket during the delay portion of their engine's burn--i.e. when loaded with a D12-3, the boosters stay attached to the rocket for an unnecessary 3 seconds.

Can I make a motor with a shorter ejection charge? Has anyone tried adding an ejection charge to a D12-0 or adding a thin delay followed by an ejection charge to effectively create a D12-0.5?

View attachment 534938

View attachment 534939

Thanks to everyone who suggested just using a zero-delay motor. D12-0 motors in the boosters worked great! The next phase of this project is to upgrade to AP motors, which means I'm going to probably have to take @cerving 's advice to use electronic ejection. Fortunately, I have a few of his Quantums laying around my rocket workshop.

Let's not bail on this adding a delay just yet.... spit balling here:

Why couldn't a fuse be used on top of the motor, the fuse runs through some wadding, then when the burning fuse exits the top of the wadding it ignites the BP ejection charge?​

​

​

 

[Daddyisabar]

One thing. Black powder research motors are prohibited at Tripoli launches.

The worst thing you could do is to put a neophyte BP charge on top of an already highly regulated, expolsive black powder rocket motor. Super illegal for the idiot teaming masses. Got to be a crazy Pyro with an explosives license and magazine to even think of such a dangerous modification. To do otherwise is to invite the guys in black SUVs to drive up with their blue jackets with yellow letters on the back and take you away, never to be seen again. Love the ways of the old country. They will keep you safe!

 

[Charles_McG]

I’ve also put a little loose BP on top of the -0. No delay, just enhancing the body tube pressure. That was on my Titan IIIe.

But it makes for a high speed deployment that’s hard to manage, recovery-wise.

So on my 1:100 Shuttle, I spring loaded the boosters and tether them to the main fuel tank with fishing line -thru- the tank. An Eggtimer Quantum sits inside to hot-cut the line, freeing the boosters so they can slow down and deploy more reasonably with a normal delay motor.

 

[Daddyisabar]

Let's not bail on this adding a delay just yet.... spit balling here:

Why couldn't a fuse be used on top of the motor, the fuse runs through some wadding, then when the burning fuse exits the top of the wadding it ignites the BP ejection charge?​

​

​

Adding an ancient technology fuse makes it even worse! Just stubborn old dudes who can not make the leap out of the nifty fifties October Skies to the latest, 21st century, awesome modern electronic deployment! Probably a very naughty boy shooting spit balls and dunking the curly long hair of the girl in front of him in the ink well! Olde tyme days the millennials can not fathom.

 

[lakeroadster]

Adding an ancient technology fuse makes it even worse! Just stubborn old dudes who can not make the leap out of the nifty fifties October Skies to the latest, 21st century, awesome modern electronic deployment! Probably a very naughty boy shooting spit balls and dunking the curly long hair of the girl in front of him in the ink well! Olde tyme days the millennials can not fathom.

Sometimes, some of the old ways are still good.

Never did the ink well thing... to busy making ramps to jump my banana seated, cheater slicked, ape hangered, Huffy bike over.

 

[Daddyisabar]

Let's not bail on this adding a delay just yet.... spit balling here:

Why couldn't a fuse be used on top of the motor, the fuse runs through some wadding, then when the burning fuse exits the top of the wadding it ignites the BP ejection charge?​

​

​

Yeah Mr. RSO. I have a lot of left over red lable booster motors I want to build a delay and ejection charge into. I'm really good with Canon fuse, used it all the time as a kid. I can get more accurate delays than the commercial motors from the hobby shop!

FIVE ONE FIVE O, BETTER CALL THE PO PO!

 

[kuririn]

Never did the ink well thing... to busy making ramps to jump my banana seated, cheater slicked, ape hangered, Huffy bike over.

With the playing cards stuck in the spokes.

 

[Daddyisabar]

Sometimes, some of the old ways are still good.

Never did the ink well thing... to busy making ramps to jump my banana seated, cheater slicked, ape hangered, Huffy bike over.

Yeah, you have to be a REALLY OLD DUDE to have used ink wells learning that obsolete cursive writing style. The modern two thumb text typing thing on the fancy phone is way beyond me. Fingers too fat and eyes too bad. My daughters laugh at me writing text on the phone!

Nothing can stop you from riding a wheely on your old banana seat Schwinn Sting Ray, until you wake up from the dream!

I would always ride no handed, clutching the Estes Range box, all the way to the corn field at the edge of town. Going to launch a diamond pack of B14 motors...dream on! Good old days!

 

[lakeroadster]

Yeah, you have to be a REALLY OLD DUDE to have used ink wells learning that obsolete cursive writing style. The modern two thumb text typing thing on the fancy phone is way beyond me. Fingers too fat and eyes too bad. My daughters laugh at me writing text on the phone!

Nothing can stop you from riding a wheely on your old banana seat Schwinn Sting Ray, until you wake up from the dream!

I would always ride no handed, clutching the Estes Range box, all the way to the corn field at the edge of town. Going to launch a diamond pack of B14 motors...dream on! Good old days!

Schwinn Sting Ray, oh, you're from that side of town... jk

As a country kid, I fondly remember packing up the range box and strapping it to my 5-speed Huffy, and riding 5 miles to my buddy Tracy's house. We'd launch in the tilled field across from his house in the spring and fall. Good times for sure.

 

[Daddyisabar]

Schwinn Sting Ray, oh, you're from that side of town... jk

As a country kid, I fondly remember packing up the range box and strapping it to my 5-speed Huffy, and riding 5 miles to my buddy Tracy's house. We'd launch in the tilled field across from his house in the spring and fall. Good times for sure.

My father was an avid bike collector. Still have the utilmate Huffy Dream Boat from the Sears catalog. Original mint condition.

 

[lakeroadster]

View attachment 539281
My father was an avid bike collector. Still have the utilmate Huffy Dream Boat from the Sears catalog. Original mint condition.

What year is this from? Looks like a knock off. Nothing like this was on the street back in the day.

 

[Daddyisabar]

Schwinn Sting Ray, oh, you're from that side of town... jk

As a country kid, I fondly remember packing up the range box and strapping it to my 5-speed Huffy, and riding 5 miles to my buddy Tracy's house. We'd launch in the tilled field across from his house in the spring and fall. Good times for sure.

There in lies the secret. Show up with a Hot Rod, ride up to the RSO table on a 5 speed Screamer, pull out a 3 stage Astron Fireside or a mighty D Colossus and the old dudes will be so inthralled with your awesome toys you can launch a zero delay with a fuse and no one will even notice!

 

[Daddyisabar]

What year is this from? Looks like a knock off. Nothing like this was on the street back in the day.

It is the real McCoy. Same era as the Schwinn Krates so 1968ish to '72. Muscle bike era. These were mainly on the "mean" streets of the big cities. No one in my small town had one or even a Schwinn Krate which were even more expensive. "OH DADDY, CAN I LAUNCH MY MIGHTY D OVER BY THE CADDY SHACK?" Just keep it in the fairway son!

P.S. I think this one is the last model from 1972. I will have to find dad's old notes on the serial numbers. In '72 I was more into GI Joe at six years old. So these bikes were more for late era baby boomers.

 

[lakeroadster]

It is the real McCoy. Same era as the Schwinn Krates so 1968ish to '72. Muscle bike era. These were mainly on the "mean" streets of the big cities. No one in my small town had one or even a Schwinn Krate which were even more expensive. "OH DADDY, CAN I LAUNCH MY MIGHTY D OVER BY THE CADDY SHACK?" Just keep it in the fairway son!

P.S. I think this one is the last model from 1972. I will have to find dad's old notes on the serial numbers. In '72 I was more into GI Joe at six years old. So these bikes were more for late era baby boomers.

So ye ole interweb says that bike is a Sears Screamer, built by Murray. And it's worth a small fortune... to the right buyer.

 

[BDB]

I’ve also put a little loose BP on top of the -0. No delay, just enhancing the body tube pressure. That was on my Titan IIIe.

But it makes for a high speed deployment that’s hard to manage, recovery-wise.

So on my 1:100 Shuttle, I spring loaded the boosters and tether them to the main fuel tank with fishing line -thru- the tank. An Eggtimer Quantum sits inside to hot-cut the line, freeing the boosters so they can slow down and deploy more reasonably with a normal delay motor.

@Charles_McG - I really need to give you credit for this project. I remember that you put boosters on a Ventris years ago, and it has always had me wanting to do something like that. Now you are going to make me want to do something with the spring/hotwire idea.

 

[Charles_McG]

@Charles_McG - I really need to give you credit for this project. I remember that you put boosters on a Ventris years ago, and it has always had me wanting to do something like that. Now you are going to make me want to do something with the spring/hotwire idea.

Just a reminder. I can take close up photos if you like.

https://www.rocketryforum.com/threads/lpr-space-shuttle-build-just-for-neil_w.143731/