OK, somehow I thought Flint's 'specialty' was nozzleless motors. I must have missed the caseless project :-\ Richard On Wed, Dec 17, 2014 at 10:49 AM, Redacted sender monsieurboo@xxxxxxx for DMARC <dmarc-noreply@xxxxxxxxxxxxx> wrote: > IIRC Flint's caseless motors were a sugpro project and have flown > successfully. If I can find the history in my archives I'll pass it along. > > Cheers, > Mark L. > > > > -----Original Message----- > From: Richard Nakka <richard.rocketry@xxxxxxxxx> > To: sugarshot <sugarshot@xxxxxxxxxxxxx> > Sent: Wed, Dec 17, 2014 11:44 am > Subject: [SS2S-Main] Re: Successful Rosetta launch > > Thanks for posting the update on your work, Flint, and congratulation > on the successful Rosetta flight. If I understand correctly, your > motor was a core burner, with cast-in-place propellant? > Your proposed "tubeless" rocket motor sounds cool, it'd certainly be > interesting to hear how that turns out. > cheers, > Richard > On Mon, Dec 15, 2014 at 2:22 AM, flint hapirat > <dmarc-noreply@xxxxxxxxxxxxx> wrote: >> Hi All, >> Had a launch (after 2+ years!) last week. >> Apart from the regular spin burner (nice! - I'm still in love with those >> Jimmy!!!!) and nozzless "regular" KNSB motors, it was a first successful >> Rosetta launch. >> The Rosetta flight was very pleasing - using a single ematch all 3 cores >> ignited instantly and the motor took off but reached a fairly low apogee >> (not measured). >> Longer cores will be used next time to have it reach a higher apogee. >> Also, >> a larger mold for these motors will be used (approx 50mm OD, with 7 cores) >> I did take a video but except for the initial launch, the liftoff sound >> and >> a bright reddish-yellow spot in the sky you don't see much... so I'll skip >> it. >> So far it's the heaviest motor I've ever made to lift off the pad - approx >> 200gr (yes, I know it's peanuts to most of you guys... but remember where >> I >> live... restrictions and all that). >> >> Specs below in case you are interested - >> The Rosetta grain had 3 cores 4mm OD, 110mm long each, it was 30mm OD >> total >> and 150mm tall. A 5mm thick cardboard tube was used as a body. >> The propellant was Serge's KN-NaN-Sb (sorbitol) with 1% RIO and was molten >> at 220c, and poured easily into the mold. >> The mold was filled up to the top of the core rods and a cardboard hemi >> was >> placed over the cores - forming a void above the cores, thus connecting >> them. >> Once the fuel cooled a bit the motor was filled again to the end of the >> cardboard tube thus forming the plug at the top of the motor. >> The grain was ignited using a single e-match that is 155mm long. Prior to >> ignition a small amount of BP grit (can't recall the mesh size) mixed a >> small amount of with fine Mg grit (roughly 1:10 Mg:BP). The same mix was >> used for the e-match (mixed, added to the ematches and finished during >> launch - not stored!!). >> >> For the next motor a triangular connection of all the core rod tips will >> be >> done using quick match. This will allow me to pour the KNS and fill the >> entire motor tube in one go. This will also provide a stronger structure >> (not weakened by the dome structure I've used this time. Also, the next >> motor will be tube-less (i.e. no nozzle, no tube, no cap - just a solid >> propellant grain). >> As a side note I'll add I'm also thinking of adding a pre-cast grain of >> KNS-Ti to this motor so the video will show something more interesting >> than >> a tiny red spot in the sky. >> If all goes well and there is an interest in this project - I'll post a >> report. >> Hope you guys find this interesting/useful... >> Cheers, >> Flint >> http://www.pyrosystems.com/flint/ >>