Where can I go on the Internet to learn about gap staging?
TIA
Andrew From Texas
Where can I go on the Internet to learn about gap staging?
TIA
Andrew From Texas
Will gap staging work with 1/2a to D size engines?
Andrew
Black powder booster motors do not have ejection charges or even delays. A booster motor just contains the very hard slug of highly compressed propellant and a clay nozzle.On a similar note, is the ejection charge from a motor with a standard delay sufficient to ignite a second stage, or the ejection charge different in motors intended to be used as boosters?
I would of course make sure that the rocket would still be traveling at a high enough velocity when the second stage lights, but it could make for an awesome effect, looking like an air-start.
Why not go to the source "the Hand book of Model Rocketry" G. Harry Stine was the innovator of the method back in the 60's. Its contained in the chapter on Staging which has all ya need to know in any edition you might come across.
EVERY rocketeer should own that book, imho. :2:
Worked like a charm. I've used gap staging now on several rockets without a problem.
True, but the guy did ask for online sources of information.
What kind of mess did the residue leave? I'm getting a bird with gap-staging ready to go, if our field ever dries out, and I was kinda wondering about that.
Heh, not bashing. Just stating.
Oooh I bet that is interesting. Any ideas why? Safety?
To go into a little more detail, an ejection charge is composed of grains of BP that are lightly tamped into the motor. At ejection, these grains break up into individual small grains, giving it a ton of surface area and allowing it all to burn almost instantly, creating a lot of gas. The particles burn up before traveling very far. It's more than just flame to ignite an upper stage, because you will see a flash of flame sometimes when motors eject. It's the burning (flaming) particles with some mass to them that do the trick.
The propellant part of all motors starts out as powder, but is compressed into one solid slug and burns from one end to the other. When the booster burns through, what's left of the slug breaks into several large chunks that have enough momentum to travel up the rocket and into the nozzle of the sustainer. The chunks are also big enough that they won't burn up before getting there.
Ejection charges won't reliably ignite upper stage motors. I remember reading about someone testing it years ago and they did get ignition occasionally, but the percentage was very low. Think of it this way. Had you rather quickly pass your hand over an open flame, or had you rather get hot coals dumped on you? :y:
Don't forget the sudden release forward of the thrust chamber pressure, acting as a piston to drive the remaining propellant straight at the sustainer's nozzle. With dozens, perhaps even hundreds, of flaming bits of propellant being flung at the nozzle throat with some force, I would think that the odds of at least one bit (and probably more like many bits) entering the nozzle ought to be pretty good. Think about a couple of analogues: flash pan ignition and the so-called spider ignition aid for clusters. Both methods require that when a small quantity of black powder is burned, enough flaming bits or sparks will randomly work their way across a gap and into the nozzles of a set of motors positioned nearby to achieve near simultaneous ignition of every one of those motors. Pulling that off seems, at first glance, like it would be a pretty tall order, with a high failure rate. Yet that's exactly what happens; both methods are known to be quite reliable. It seems reasonable to conclude that a similar process takes place within the enclosed confines of a stage gap (or even in a totally open gap, such as in Intruder's Aerobee), where the sparks or bits only need to find their way into one nozzle (while getting a big push from behind, to boot). The standard description of this process seems like a no-brainer to me.Several decades of research by many in the hobby and professional rocketry on the subject have provided inconclusive results; We DO NOT KNOW what causes upper stage ignition, but it's fairly obvious staging would not be nearly as reliable as it is, if it were left to random chance a chunk of burning propellant to hit those small nozzle openings alone to do the job....
Back to igniting those upper stage motors; It could be any one or combination of Heat, Radiation, and hot particulates that bring the cold BP up to combustion temperature. I'm presonally in the heat & radiation camp bringing the BP up to temp as these travel more or less in a straight line where particulates are more subject to pressure (Burst or burn through) release changes and venting.
It is not only possible to use a standard delay/ejection charge motor to reliable ignite upper stage motors It can be very helpful in some long coast phase optimum mass models IF and I say again IF all the math as been done and choosing a motor delay combiniation that matches up with the most high speed forward coast time of the model. This was done this year at Naram winning the event.
but it's fairly obvious staging would not be nearly as reliable as it is, if it were left to random chance a chunk of burning propellant to hit those small nozzle openings alone to do the job.
You guys crack me up LOL!!!
I'll be waiting to see your test results, and report Can't wait to be enlightened.
I'm sure it would also make you uneasy to know many a competitior has used red labled booster motors in very small upper stage models to deploy a recovery system or streamer. Manufacturers have purposely been quite broad in their scope as to what is and is not allowable with there products.
Booster motors are intended to be used for just that, Boosting lower stages or in clusters along with delay and ejection charge fitted motors. It's not a hard concept, almost common sense one would think. The motor has a RED lable marked "Booster" motor, Let's use them as the manufacturer intended.
Now let's get back to the subject of clustering Estes SR-71.
All that considered, What I'd like everyone reading this thread to understand is This:
"Booster motors ARE NOT INTENDED by the Manufacturer, to be used to deploy a recovery system...PERIOD".
The motor manufacturers make this FACT very clear. We as responsible modelers should NOT be promoting a process or proceedure that is a direct contridiction to the manufacturers intended and expressed insturctions. Can this be expressed any more clearly? Booster motors are NOT to be used in place of single or upper stage motors at have a delay train.
Pretty sure he meant that the concept of gap staging will work for 1/2A through D engines, not a 1/2A lifting a D...
Still, an interesting concept. If I could get my hands on a few A10-0 or A8-0, it could make for a seriously awesome flight with a D on top. Lifting up 10-20 feet, dropping the booster, and then shooting off for the stars.
On a similar note, is the ejection charge from a motor with a standard delay sufficient to ignite a second stage, or the ejection charge different in motors intended to be used as boosters?
I would of course make sure that the rocket would still be traveling at a high enough velocity when the second stage lights, but it could make for an awesome effect, looking like an air-start.
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