Post by thread:[OT]: Modern Pulse jet enginedevelopment

NZ based man developing a modern pulse jet with some original ideas. Bruce is a competent engineer and has had substantial success in other areas of endeavour. A must see site for anyone with any sort of interest in pulse jets or amateur built aero engines of any sort. http://www.aardvark.co.nz/pjet/ IMHO his attention to personal safety appears inadequate for systems with this level of danger. An example engine has 100 pounds thrust in an easily man-portable unit that looks something like a fattish Bazooka. He has used it to power a Go-Kart. ___________ Site ref from David L -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On Mon, 27 Jan 2003, Robert Ussery wrote: *>This guy really gets around! *>He posted on the Soaring Usenet group on Google (rec.aviation.soaring), *>suggesting that his designs be used to power some of the lighter sailplanes. *>Yeah right! Hey, you could use a V1 engine instead and get more credibility (and tinnitus). That Hiller trombone device has very low compression ratio so its efficiency is low. But so has the V1 engine ... there was someone on this list who said he flew a pulse jet model airplane some time ago, maybe they want to chip in on this thread. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> *>This guy really gets around! > *>He posted on the Soaring Usenet group on Google (rec.aviation.soaring), > *>suggesting that his designs be used to power some of the lighter sailplanes. > *>Yeah right! > > Hey, you could use a V1 engine instead and get more credibility (and > tinnitus). That Hiller trombone device has very low compression ratio so > its efficiency is low. But so has the V1 engine ... there was someone on > this list who said he flew a pulse jet model airplane some time ago, maybe > they want to chip in on this thread. One working model of Bruce's engine produces about 100 lbf thrust. The V1 produced about 600 lbf. Bruce uses his to power a gokart. Apart from the terrible noise it would be an entirely practical sailplane motor. The V1 carried a 1 ton payload and travelled at about 400 mph. As air drag rises as the cube of velocity a V1 size craft might be expected to exceed 200 mph with Bruce's engine in level flight !!!!!!!! ((600/100)^0.333 ~= 1.8) A smaller craft would go faster. A jet or rocket engine of any sort has the interesting attribute of producing more effective power with increasing speed due to the P = V x F relationship. (At standstill it delivers no true power at all - only force. At 200 mph a 100 lbf motor produces about 30,000 ft-lbf/sec or about 60 horsepower. Entirely adequate for a small craft. Takeoffs would be another matter. The V1 had the same problem and used a peroxide powered steam catapult to do the honours. In the case of a sailplane the time honoured alternative is a car with a tow rope. Once airborne the pulsejet would take it to altitude with ease. A photo shows Bruce holding the 100 lbf unit and its not overly large on the Go kart. V12 consumed 3.5 lb of fuel per lb thrust per hour. Bruce's is, presumably, more efficient. Russell McMahon -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Russel I think that it's the power requirement that goes up with the cube of velocity. Force goes up with the square ?? Still works out at 163mph however! Richard Russell McMahon <apptech@PARADI To: spam_OUTPICLISTTakeThisOuTMITVMA.MIT.EDU SE.NET.NZ> cc: Sent by: pic Subject: Re: [OT]: Modern Pulse jet enginedevelopment microcontroller discussion list <PICLIST@MITVMA .MIT.EDU> 28/01/03 13:43 Please respond to pic microcontroller discussion list > *>This guy really gets around! > *>He posted on the Soaring Usenet group on Google (rec.aviation.soaring), > *>suggesting that his designs be used to power some of the lighter sailplanes. > *>Yeah right! > > Hey, you could use a V1 engine instead and get more credibility (and > tinnitus). That Hiller trombone device has very low compression ratio so > its efficiency is low. But so has the V1 engine ... there was someone on > this list who said he flew a pulse jet model airplane some time ago, maybe > they want to chip in on this thread. One working model of Bruce's engine produces about 100 lbf thrust. The V1 produced about 600 lbf. Bruce uses his to power a gokart. Apart from the terrible noise it would be an entirely practical sailplane motor. The V1 carried a 1 ton payload and travelled at about 400 mph. As air drag rises as the cube of velocity a V1 size craft might be expected to exceed 200 mph with Bruce's engine in level flight !!!!!!!! ((600/100)^0.333 ~= 1.8) A smaller craft would go faster. A jet or rocket engine of any sort has the interesting attribute of producing more effective power with increasing speed due to the P = V x F relationship. (At standstill it delivers no true power at all - only force. At 200 mph a 100 lbf motor produces about 30,000 ft-lbf/sec or about 60 horsepower. Entirely adequate for a small craft. Takeoffs would be another matter. The V1 had the same problem and used a peroxide powered steam catapult to do the honours. In the case of a sailplane the time honoured alternative is a car with a tow rope. Once airborne the pulsejet would take it to altitude with ease. A photo shows Bruce holding the 100 lbf unit and its not overly large on the Go kart. V12 consumed 3.5 lb of fuel per lb thrust per hour. Bruce's is, presumably, more efficient. Russell McMahon -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

----- Original Message ----- From: "Russell McMahon" <.....apptechKILLspam@spam@PARADISE.NET.NZ> > terrible noise it would be an entirely practical sailplane motor. The V1 > At 200 mph a 100 lbf motor produces about 30,000 ft-lbf/sec or about 60 A sailplane at 200mph??? Whats the max speed on most sailplanes?? I would have thought most would not enjoy 200mph for very long.... Ben -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

From: "Benjamin Bromilow" <btbromilowKILLspamLINEONE.NET> > A sailplane at 200mph??? > Whats the max speed on most sailplanes?? > I would have thought most would not enjoy 200mph for very long.... Nope, they wouldn't. Most of them won't do more than 150. With the fairly negligable thrust produced by a pulsejet standing still, it would be necessary to launch them with a winch or auto tow. Also, most sailplanes spend the majority of their time thermalling at speeds from 50-60 mph. I'm not sure if a sailplane flying at 150 would climb at all, either, both because best climb speed is usually near 60 mph and because the angle of attack would be so low at that speed that the sailplane would be dropping like a rock already and hardly producing any lift. With the pulse jet, it might be able to maintain altitude, but I doubt it would be able to climb. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

Hi Robert, Why are you saying the AOA would be so small? There shouldn't be anything to stop the pilot from raising the nose and increasing the AOA, as far as I see it. Do sailplanes have a "best climb" speed? I thought that was for powered airplanes only, as a compromise between engine power, lift, and drag. AFAIK, a sailplane cannot perform a sustained climb relative to the air around it, so technically there is no such thing as a sustained climb for a sailplane. A thermal just means that the air around the sailplane is rising faster than the sailplane is falling in it. Sean At 09:57 AM 1/28/2003 -0700, you wrote: {Quote hidden}>From: "Benjamin Bromilow" <.....btbromilowKILLspam.....LINEONE.NET> > > A sailplane at 200mph??? > > Whats the max speed on most sailplanes?? > > I would have thought most would not enjoy 200mph for very long.... > >Nope, they wouldn't. Most of them won't do more than 150. With the fairly >negligable thrust produced by a pulsejet standing still, it would be >necessary to launch them with a winch or auto tow. Also, most sailplanes >spend the majority of their time thermalling at speeds from 50-60 mph. >I'm not sure if a sailplane flying at 150 would climb at all, either, both >because best climb speed is usually near 60 mph and because the angle of >attack would be so low at that speed that the sailplane would be dropping >like a rock already and hardly producing any lift. With the pulse jet, it >might be able to maintain altitude, but I doubt it would be able to climb. > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

From: "Sean H. Breheny" <EraseMEshb7spam_OUTTakeThisOuTCORNELL.EDU> > Why are you saying the AOA would be so small? There shouldn't be anything > to stop the pilot from raising the nose and increasing the AOA, as far as I > see it. AOA is directly related to airspeed for a given AOA, the glider will fly at a given airspeed. This is a property of the airfoil used and cannot be changed (except for w/ flaps and other devices that adjust the shape of the wing). If the pilot raises the nose, he will increase the AOA and slow down. This is all dependant on the power to weight ratio of the aircraft in question, of course. Aircraft with lots of power may maintain a given AOA at a high pitch angle. For sailplanes, however, a given AOA (and pitch angle - without power, they're equivalent) will result in a given airspeed. > Do sailplanes have a "best climb" speed? I thought that was for powered > airplanes only, as a compromise between engine power, lift, and drag. > AFAIK, a sailplane cannot perform a sustained climb relative to the air > around it, so technically there is no such thing as a sustained climb for a > sailplane. A thermal just means that the air around the sailplane is rising > faster than the sailplane is falling in it. There are two "performance" speeds in gliders. You have the minimum sink speed (usually 5 or so knots above stall) which the glider uses to stay in the air for the longest period with a given altitude. This is equivalent to maximum climb angle in a power plane (Vx, I think). The second speed is best L/D speed, the speed at which the lift to drag ratio is greatest. At this speed, the glider will travel the greatest distance over the ground for a given altitude loss. This is equivalent to best rate of climb in a power plane (Vy?). Minimum sink is used for thermalling because it permits a tighter circle in the thermal. Best L/D is used between thermals or on long cross-country runs. Your definition of a thermal is correct, in that a positive rate of climb relative to the surrounding air is impossible. However, minimum sink speed results in the least altitude lost per unit of time in the thermal and thereby permits more efficient use of the rising surrounding air mass. The lower the glider's sink rate, obviously, the higher the rate of climb in a thermal, when compared to a glider with a higher sink rate. - Robert -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.