fredhappy Posted May 11, 2013 Posted May 11, 2013 These are two girandola's I've made recently together with a friend of mine. We like building these things on a saturday evening, then shooting them around midnight. They are a lot of work!! For pressing the endburners I've used a press sleeve made by my pyro friend. This is a great tool, it enables me to press larger increments with a much higher pressure. The fuel core is very evenly supported by the press-sleeve, as opposed to those terrible hose clamps I was using before. Also, with a press sleeve work times are much faster. The first one had 8 drivers. It did not have any horizontal drivers. 2 small steel fountains were attached. Due to the fact that we'd pressed metal in the endburners, the steel fountains were a bit washed out. http://www.youtube.com/watch?v=KqVPLhuIP34 Also, the lack of horizontal drivers resulted in a somewhat curved flight path. The sound of these girandolas is just amazing, like some sort of weird jet engine taking off...very very cool, I absolutely love them. http://www.youtube.com/watch?v=fyFL9GKQrck The second one was better imo. It had 3 drivers, 2 horizontal drivers and 1 glitter fountain attached to the side. I really like horizontal drivers on girandolas. They make a very cool beginning effect, and the liftoff is always a bit of a surprise. This one flew straight as an arrow, the gyroscopic effect of the horizontal drivers had a profound influence on the stability and flight trajectory. Best is not to add any metals to the egines , and use fountains/comets as special rising effects. fred
VikingPyrotechnics Posted May 11, 2013 Posted May 11, 2013 I love the 2ndYep, the sound of Dolas is great. Nice Dolas, looking forward to the next ones VP
pyrokid Posted May 11, 2013 Posted May 11, 2013 Very nice work, Fred! I think you have inspired me to attempt some girandolas.
WonderBoy Posted May 13, 2013 Posted May 13, 2013 Nice Fred! Those were great. Now it's time for a little heading WB
fredhappy Posted May 14, 2013 Author Posted May 14, 2013 #all : thanks for your comments guys, I really appreciate. #wonderboy : I did attach a little 3"header on another 4x1lb dola with rather cataclysmic results...... http://www.youtube.com/watch?v=WbK7S_mLM4wspintest, all looked well.. http://www.youtube.com/watch?v=sVQwPup52EA The dola started nicely with slowed down horizontal drivers +coarse Fe/Ti. But my new and "improved" method of fusing the engines resulted in two engines firing slightly earlier then the other two.After liftoff the dola continued an almost perfect horizontal flight at about 20 meters....I was pretty rattled by this and even forgot to capture the header going off..it did go off though, so on the positive side, nothing was wrong with my way of fusing the header....
VikingPyrotechnics Posted May 14, 2013 Posted May 14, 2013 With a header on it, it is harder to keep the Dola stable.I think a few more 1lb motors would help there?! anyway, very nice try. VP
fredhappy Posted May 14, 2013 Author Posted May 14, 2013 #viking: thrust was not an issue. I use super hot 70-18-12 for my endburners, they can really lift stuff. The issue was not igniting all the engines at once. This is very important with dolas. I tried fusing the two horizontal drivers with 2 engines each. This was a bad idea. I always carefully weigh down all my increments for my drivers/rockets etc. However, there was some variation in burntime, somewhere in the range of 0.5 seconds , even when you press the exact same amount of fuel in the driver. So, best is to have one ignition point for all the engines. Otherwise, be sure to duck...these things like to go horizontal with a vengeance.
Recommended Posts