[SS2S-Main] Successful Rosetta launch

  • From: "flint hapirat" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "flinthapirat@xxxxxxxxx" for DMARC)
  • To: Sugarshot <sugarshot@xxxxxxxxxxxxx>
  • Date: Mon, 15 Dec 2014 08:22:46 +0000 (UTC)

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...  

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