Hi Dave, As your are in South Africa, have you heard about the Perendev's magnetic motor? Is that for real? http://www.perendev-power.com/home.htm Mark Jordan On 4 Oct 2004 at 8:54, Dave Smith wrote: > Hi Russell > > I work for BMT Turbine's here in South Africa. I design & manufacture most of the parts used in the turbines. > > Most RC turbines have autostarts which don't really add much to the overall weight, ours weighs 1.6Kg and delivers 12-15Kg static thrust, depending on the rpm u r willing to run it at. The higher the rpm the better the compressor works. > > Our KS120 turbine goes 1 step further by being the first Kerosene start turbine. That is it does not require LPG gas to preheat the combustion chamber. All turbines have their own microcontrollers onboard to monitor temperature (+- 650 - 75deg C) / rpm ( up to 165 000rpm) / pump voltage. > > Fuel consumption is typically around 350 - 400ml per minute. > Spool up time in the region of 3 - 4 sec. Idle rpm +- 35 000rpm. > > > We r currently building a target drone for our Navy with a top speed of 650km/h. It will have 2 20Kg BMT turbines onboard and +- 36L of JetA1 fuel. > > Pictures at http://www.rcuniverse.com/forum/Halcat_%40_mach_0%255%2B/m_2151176/tm.htm > > > U can find more info about our turbines at the website below. > > http://www.bairdtech.com/bmt/BMT120.htm > > > regards > > Dave Smith > Cape Town > South Africa > > ----- Original Message ----- > From: Russell McMahon > To: PIC List > Sent: Friday, October 01, 2004 2:22 AM > Subject: [OT] Small gas turbines > > > Fronm anothe rlist. > Some good links. > > > >>Anyone in the Experimental HPR rocket arena > >>built a turbine first stage? > >> > >>Something like a Hobby Turbine... > >>http://www.robart.com/FunSonic/Turbines.aspx > > There's a whole industry booming up with little jet turbines > like that, single stage centrifugal compressors originally > based on turbochargers, etc. The biggest ones are about > 150 lbs thrust. Cost seems reasonably consistent at $100/lbt > for the medium and larger ones (the Robart one is about $200/lbt, > which is typical for engines under about 35 lbt if I recall right). > > See for example: > www.gtba.co.uk (Gas Turbine Builders Association) > www.microjeteng.com (manufacturer, the biggest engines, up to 150 lbt) > www.artesjet.com (manufacturer) > www.wren-turbines.com (manufacturer) > > Thrust/weight ratios for the low end sizes are generally 5-6, > but the larger ones get better; the Microjeteng HF150 has 150 lbt > and weighs 19 lbs, for a 7.5 ratio, the HF100 is 95 lbt weighing > 10.4 lbs for better than 9, the HF30 with 32 lbt and 3.5 lbs for > better than 9 as well. The HF65 isn't so good. > > >>If I do my Math correctly Thrust to weight of between 5 and 8, depending > >>on how much of the start gear stays on the ground. > >>ISP of > 2000..... > > > >If the engine only has a T/W of 5-8, it is going to be hard to get a > >complete vehicle (let alone an upper stage) with a T/W of at least 3, > > Not as hard as with rockets... the SFC of these engines is as > good as 2.0, which corresponds to an Isp of 1800... engine, > minimal structure for the loads, an intake, fins, and a small > fuel tank... it's just more weight on the way down and > more percentage dry weight. If your rocket has a large mass > ratio then it's an issue, but if it's a moderate mass ratio > then a jet could replace it without too much pain and suffering. > > I've done some design sketches for turbo-boosters, and I can usually > keep the structural weight down to about the turbine's weight. > > For say a HF100 burning 1.4 liters/min (1.15 kg/min), with no > afterburner... > > A Mach 2 ascent requires T/W of about 2.0, so GLOW will be about > 50 lbs allowable. 11 lbs of engine, 11 lbs of structure roughly. > Mach 2 is 680 m/s, about 2200 ft/sec. It will reach 50,000 ft > in less than 30 sec and probably run out of air thereabouts, > or between there and 75,000 ft. Max fuel consumption should > be something like 1.5 liters. Afterburning is definitely the > best option. > > Payload to 50k ft / mach 2 is likely around 25 lbs with HPR grade > recovery systems. You may want to trade payload for better and > more redundant recovery, given the engine will cost $10k or so... > > > A good argument could be made > >that building an actively stabilized platform with COTS turbines may be > >easier than doing it with your own rockets... > > They are reported to spin up relatively rapidly, but I don't know > how fast they are compared to the requirements for active thrust > stabilized flight. > > The one thing that could clearly throttle that fast would be > to tack afterburners onto some of these engines. Which, for > absolute performance reasons, is probably a good idea anyways. > For very short burn times, the system efficiency is optimized by > spending more fuel and getting more thrust per unit engine > core mass. > > > -george william herbert > gherbert@retro.com > > _______________________________________________ > aRocket@exrocketry.net > http://exrocketry.net/mailman/listinfo/arocket > > _______________________________________________ > http://www.piclist.com > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > _______________________________________________ > http://www.piclist.com > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist _______________________________________________ http://www.piclist.com View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist