Staging Question

[Bruiser]

This has probably been asked before but I couldn't find it

So you can direct stage a black powder to black powder

You can not direct stage a composite to a composite

Can you direct stage a black powder to a composite?

Thanks,
-Bob

 

[kuririn]

Short answer, no because composites ignite from the front of the propellant core, not the back end.

 

[mbeels]

Short answer, no because composites ignite from the front of the propellant core, not the back end.

There are a few exceptions like the Warp 9 and Blue Thunder end burning composites. I wonder if it would work with those motors.

 

[Jmhepworth]

Even if you can, it’s not a good idea. With high power staging you need electronics, both for recovery and for ignition (not in that order). If the sustainer doesn’t light, you need something to put the chute out. And if the sustainer isn’t sufficiently vertical, you don’t want the sustainer to light. And the complexity of high power staging is part of what makes it so rewarding.

 

[Bruiser]

Not really talking high power, more mid power. Just looking at options for staging a Majestic.

-Bob

 

[neil_w]

I don't think I have ever read of someone doing BP->Composite staging. Certainly I have never seen anyone recommend doing it.

Would be interesting to run some static tests to see how well it actually does (or doesn't) work, with different propellants.

In my experience, 24mm composites light pretty quickly but I don't know if it would ever be reliably quick enough, or if the front of the motor would light.

 

[cerving]

Nope. You need electronics and a real igniter to airstart a composite motor, because 1) they light from the head end, and 2) a BP motor's flaming bits aren't enough to light an AP motor. For quick ignition, I recommend using a blue/white type of propellant, and the CTI motors with the BP starter pellet are easier to ignite than Aerotech motors with a pyrogen-coated igniter.

 

[Charles_McG]

Here's the other direction - composite to BP:
https://oldrocketforum.com/showthread.php?t=12147

There are some 24mm and 29mm end burners. I'm thinking of the Apogee E6 and F10. Thing is - they have really small nozzles. At least the F10 does. So that limits the ability for ignition. Maybe a fuse?

Example of ground lit fuse. Maybe the booster could do the lighting.
https://oldrocketforum.com/showpost.php?p=186950&postcount=19
and exactly what might work:
https://oldrocketforum.com/showpost.php?p=205901&postcount=8

 

[cerving]

The problem with composite to BP is that the composite motor doesn't send out any flaming bits to light a BP motor, at least until the ejection charge lights. You can't drill out the delay below the minimum, because doing so might cause a forward closure failure (in addition to making it non NAR/TRA legal). So, the best you can do is to drill the delay to minimum, add the BP to the well, and hope the rocket is still going "up" at a decent velocity when the ejection goes off.

 

[kuririn]

There was a thread on this a while ago, and someone was experimenting on a solution.
I'll see if I can find it.

 

[BABAR]

Here's the other direction - composite to BP:
https://oldrocketforum.com/showthread.php?t=12147

There are some 24mm and 29mm end burners. I'm thinking of the Apogee E6 and F10. Thing is - they have really small nozzles. At least the F10 does. So that limits the ability for ignition. Maybe a fuse?

Example of ground lit fuse. Maybe the booster could do the lighting.
https://oldrocketforum.com/showpost.php?p=186950&postcount=19
and exactly what might work:
https://oldrocketforum.com/showpost.php?p=205901&postcount=8

I can't get the links to work (may be because I am at a work computer on lunch break.) I will see if I have more success at home.
I was wondering this exact question, I understand why BP to composite doesn't work (or at least work reliably) but was wondering about the opposite--- a composite motor in booster lighting a BP motor in sustainer. The problem is, to my knowledge there is no off the shelf zero delay composite motor.
It has been demonstrated that it is NOT particles that light the BP sustainer motor, but PHOTONS/radiant heat (which essentially makes successfully lit black powder sustainers Photon Torpedoes!) Not sure how a composite motor can emulate the zero delay BP motors, with nothing but ignitable propellant sealing the forward end of the booster motor.

 

[Charles_McG]

I think Ted and Doug’s experiments were highly non-NAR. I seem to recall that they modified 13mm motors in to more vigorous delays- but I might be remembering wrong.

And while the fused flight might be okay for EU competition- it’s not kosher stateside. If I had a stack of E6s, it might be a little tempting to try a D12-0 to E6 that way, flying from the orchard instead of the club.

But I’ve stuffed an eggQuantum in BT55 and staged a 24mm CTI. Much better safety-wise.

 

[cerving]

I've stuffed a Quantum in a BT50 (Estes Mongoose with a few minor tweaks) and did a D21/D10... with an Eggfinder Mini in the nose. I needed it... there's absolutely no way I would have found it otherwise.

 

[mbeels]

I've stuffed a Quantum in a BT50 (Estes Mongoose with a few minor tweaks) and did a D21/D10... with an Eggfinder Mini in the nose. I needed it... there's absolutely no way I would have found it otherwise.

I'm curious, what did you do for an igniter in the D10, and what battery fits in a BT50 that could fire it?

 

[BABAR]

Here's the other direction - composite to BP:
https://oldrocketforum.com/showthread.php?t=12147

There are some 24mm and 29mm end burners. I'm thinking of the Apogee E6 and F10. Thing is - they have really small nozzles. At least the F10 does. So that limits the ability for ignition. Maybe a fuse?

Example of ground lit fuse. Maybe the booster could do the lighting.
https://oldrocketforum.com/showpost.php?p=186950&postcount=19
and exactly what might work:
https://oldrocketforum.com/showpost.php?p=205901&postcount=8

Okay, iPad works. Great articles, thanks!

 

[BABAR]

I'm curious, what did you do for an igniter in the D10, and what battery fits in a BT50 that could fire it?

Me too

 

[cerving]

I'm curious, what did you do for an igniter in the D10, and what battery fits in a BT50 that could fire it?

I used an Estes ProSeries II igniter, they fit perfectly in those 18mm D's. The battery was a 300 mAH 2S LiPo from Hobby King... https://hobbyking.com/en_us/turnigy-nano-tech-300mah-2s-35-70c-lipo-pack.html , I used the same battery for the Quantum and the Mini. That's a pretty hefty current draw for such a small battery (about 140 mA), but this was a small rocket and it wasn't going to be sitting on the pad for very long.

 

[Charles_McG]

I wanted to see what Cris said before I chimed in. I use the 45-90C version of that battery. I find it lights the PSII igniters, but a bit slowly. The Aerotech Firstfire Micro (I’m pretty sure it’s not the Mini) fires quicker on the same battery and is ‘sparkier’.

From the published dimensions, I thought the 45C version was supposed to be the same size as the 35C. I find it tight in BT50. So close that it’s battery to battery and maybe trim the outer heat-shrink of the Lipo. The corners are stiff and tend to stick out.

I sometimes wish I lived where I could fly with Cris. Seems like a lot of great flights - and the chance to spy on works-in-progress.

 

[BABAR]

I have only flown one composite motor.

I was looking at the anatomy of single use composite motors on Apogee's site

https://www.apogeerockets.com/Tech/How_Composite_Rocket_Engines_Work

Looks like for the FLYER to modify a single use motor to use as a gap stage igniter for a sustainer (i.e., no electronic staging) would be, let's say, touchy at best.

If the MANUFACTURER replaced the delay grain with regular propellant and left off the ejection charge and paper cap, would this function similarly to a BP zero delay motor? You would want the length of the solid segment of propellent in the previous "delay grain" section to be sufficient to make sure all the main propellant was burned before the "delay grain" section burns through.

Put another way, any chance Quest might come up with a zero delay composite 18 mm booster motor for non-electronic staging? Lots of reason they wouldn't, only one of which is that it could only stage to an ESTES black powder motor.

@Charles_McG post 8 , reading the links was interesting regarding the concept of an ideal delay between booster burnout and upper stage ignition (if you are shooting for optimum altitude), certainly much harder to do withOUT electronics.

 

[Nytrunner]

Composite delays are basically a slow burning apcp formulation. There are instructions not to drill them down below 4 seconds due to the remaining thickness of delay material not being strong enough to contain the chamber pressure.

What I wonder is why fusing isnt allowed stateside, or why the safety code may prohibit it

 

[kuririn]

The current NAR safety code specifies electrical ignition for the launch of all model rockets, but....
There are (were) at least two model rocket kits that I know of that used a fuse to light their second stage.
Modified instructions for the Centuri Black Widow #KB-6 recommend folding Jetex wick (fuse) and packing it into the nozzle of the sustainer motor. And the Heavenly Hobbies Backdraft uses a visco safety fuse to light the upper motor that acts like a retro rocket to minimize drift on recovery. The fuse is necessary because the retro firing motor's nozzle faces away from the top of the booster motor.
https://www.oldrocketplans.com/centuri/cenKB-6/cenKB-6.pdf
(Scroll down to modification instructions).
https://store.heavenlyhobbies.com/01-024-0001.html
So maybe fuses/Jetex/thermite are OK for second stage ignition?
Or maybe they were at one time but no longer?
Or maybe it's a gray area?
Cheers.

 

[Nytrunner]

If everything must be electrically ignited, then all our blackpoder stagers are in trouble

 

[kuririn]

for the launch of all model rockets

 

[Bruiser]

Just me and I'm no lawyer but to me "launch" is liftoff...

-Bob

 

[kuririn]

That's how I read it too.
But the NAR doesn't specifically mention whether fuses for second stage ignition is OK.
I don't think kits would have been put into production if this wasn't allowed, at least at the time.

 

[new2hpr]

Don't confuse thermalite with thermite. Very different stuff. Thermalite fuse is what we wish we could still use. Great for clusters and similar fun stuff. Leave the thermite for the big guys!

 

[kuririn]

Long, long ago, in a galaxy....never mind.
I was musing on a long past thread about putting a fuse in a BP sustainer coupled to a composite RMS booster motor. The booster would have the ejection grains uninstalled and the fuse would run through the hole in the ejection well into the composite motor's delay grain. I don't think this would constitute modification of a motor, as you are merely leaving something out, like when you launch an oddroc that doesn't need an ejection charge.
Anyhoo, if you drill the delay down to the minimum then maybe you could get successful composite to BP staging? Somebody mentioned experiments on this but I can't find the thread. I'll keep digging.

 

[kuririn]

Don't confuse thermalite with thermite.

Sorry, early onset dementia kicking in.
But thermite would be WAY more entertaining.
Laters.