terryg
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Did the flash pan method used have just a layer of black powder or were tubes used to direct the flames into each engine?
Black Powder High Power
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Did the flash pan method used have just a layer of black powder or were tubes used to direct the flames into each engine?
A pie tin with an even layer of BP. I've not heard of tubes being used. That sounds explosive...
Sooner Boomer
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An example of using a flash pan for cluster ignition:
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I guess it is a thing. Learned something new. Probably not the best method for lighting 50+ motors.
For straight ahead flash pan ignition, one thing @kramer714 taught me before the Pumpkin Pi flight was to coat the pan in a very light layer of grease. The grease holds the BP where you want it if a breeze comes up.
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lr64
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That would depend, in part, on the strength of the tubes. Anything permanent might benefit from a disposable blow out panel, maybe just paper or cardboard. Maybe you could use drinking straws for tubes.
Fireworks guys have something they call quick match, which is just black match style fuse with paper wrapped around it or in a paper tube. Apparently, the tube makes the fuse inside burn far faster. Black match, as I recall, is just cotton string that's been run through a slurry of black powder, water, and maybe a little dextrin. There are other things you can use instead of dextrin, but it's traditional. Anyway, I think they have the simultaneous launch thing figured out. I could see running quick match from some central charge up into the nozzle of each motor. The quick match could be held in place with a bit of flammable glue. This way, even if the rocket lifted off with only some of the motors lit, the others might be carrying quick match that would light them in short order.
Notice that I didn't say anything about the composition of the black powder.
shockie
High Plains Rocketeer
Anybody got a close up shot in slo-mo of flash pan ignition? 4F BP?
Rocketjunkie
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This is how I did it in 2003. Each motor had a short fuse and a few grains of BP. Now I'd just use MJG BP motor starters in each motor.
Clear packing tape covered with BP and Estes starters to light the BP which lit the fuses.
Clear packing tape covered with BP and Estes starters to light the BP which lit the fuses.
Wish me luck.
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Good luck, friend!
User name checks out...
shockie
High Plains Rocketeer
Not real sure of the purpose of these perforated discs, but it's my understanding they are blown off at motor ignition. The photo is from Europe.
Sooner Boomer
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Wish I could see those go off! Take videos!
I hear about flash pan, I assume it is reasonably reliable. I think it is also mentioned even in the old versions of Stine's book. I used to wonder if some kind of little funnels would help to direct the flame up into the nozzles but it would be tedious to build.
I used brass tubes in a spider inspired configuration to light 30 C6-5 engines. Very high success rate with it.
PLEASE
All good.
Turns out printing these motor cartridges in PETG made them single-use. That actually simplifies things for me in the future, but it does mean I'm done flying black powder high-power for the weekend. Tons of fun was had!
According to ThrustCurve.org > Compare C6 and F15 ...
22 Estes C6 motors would have a TMT designation: 194H102
And 8 Estes F15 motors would be in TMT-ese: 397I113
Wow !
Talk about Black Powder High Power !
Congrats @bad_idea !
-- kjh
22 Estes C6 motors would have a TMT designation: 194H102
And 8 Estes F15 motors would be in TMT-ese: 397I113
Wow !
Talk about Black Powder High Power !
Congrats @bad_idea !
-- kjh
Thanks, Konrad! Glad you made it up to Seymour again.According to ThrustCurve.org > Compare C6 and F15 ...
22 Estes C6 motors would have a TMT designation: 194H102
And 8 Estes F15 motors would be in TMT-ese: 397I113
Wow !
Talk about Black Powder High Power !
Congrats @bad_idea !
-- kjh
The dozen E12s actually made for my favorite flight of the three, but they were all a lot of fun.
Thank you, Stephen !
Shucks ! I missed your flight with a dozen E12's ( hmmm ... let's see, that would be TMT designation 326I136 )
EDIT: Please post videos if you have them ( thanks ) !
Yes-sir-ree-bob !
It was nice to actually fly a rocket at Seymour
I am trying to figure out what the violent wiggle was when "T'Pring's P'Toy" went transsonic ...
Will follow up with a launch report when I have some plots and an idea or two ...
Thanks again -- I'll be back !
-- kjh
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I caught usable video only of the third flight, of eight F15-8s. It will take some time to get that video in a state to upload.
The great Harry Spears caught photos of the 22xC6-7 and 8xF15-8 flights:
The great Harry Spears caught photos of the 22xC6-7 and 8xF15-8 flights:
OMG !
Beautiful pics !!
Harry is a magician
-- kjh( how does he DO that ? )
Beautiful pics !!
Harry is a magician
-- kjh( how does he DO that ? )
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Looks like your fins were successful. Post up somewhere about that.
Does that smell like old fashioned gun powder in the morning?
terryg
Well-Known Member
Very cool!
What did the cartridges look like after you removed them?
What did the cartridges look like after you removed them?
Harry is an amazing photographer. Rockets, eclipses, clouds, astronomy, etc., all his photos are fantastic.
They were nothing particularly special. Used the hull trick you clued me in on because I wasn't completely happy with the available fin generator scads. 1mm radius on the leading and trailing edges, a hair over 7mm thick at the center of the root, a hair under 3mm thick at the center of the tip. Printed in PETG with leading edge up, four perimeters, 50% gyroid infill, 0.4mm nozzle, 0.15 layer height.
Tough but flexible. Not bad for subsonic flight. They survived being bounced and drug hard along the ground by wind gusts after one of the landings. Not that it's relevant to fin strength itself, but I fully expected a fin or two to be detached when I recovered that flight, as the fins are simply surface mounted to cardboard. Was pleasantly surprised to find the fins intact.
Indeed!
I'll have to find where I put them and grab a photo. They're heat warped on the sides, and the plastic seemingly flowed into the channels for the retention bolts and seized them solid. Tried to remove one of them with pliers and sheared off the head.
I could perhaps get them to hold up better if printed in polycarbonate, but I think I'm just going to embrace their single-use nature. In the future, I plan to print the motor cutouts slightly smaller for a few layers at the bottom, insert the motors from the top with some additional friction fit in case those bottom layers soften too much to retain the motors, and then epoxy motor blocks in place above the motors.
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