If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
Uzytkownik "robert arndt" napisal w wiadomosci om... (WaltBJ) wrote in message . com... [snip...] A pulsejet is a form of ramjet except that the combustion is intermittent rather than continuous. The pulsejet uses spring loaded shutter valves that open and close for the imtermittent pulse... but is still a ramjet that has to be launched into the air by some means other than the engine for it to work. No way! They have different thermodynamical cycles! A pulsejet uses constant volume combustion cycle while ramjet uses constant pressure combustion cycle. Since constant volume combustion cycle is a little bit more effective (in thermodynamical terms) then exist some rocket motors using this cycle. Are these rockets ramjets or pulse jets? A pulsejet motor can be started at ZERO ground speed when you supply sufficient airstream. Once started pusejet will wor fine when you cut this additional airstream. You can start ramjet in the same way, but when you stop auxillary airstream ramjet will cease to work. When in high school I attended two semesters of aeroengines. I recall one lesson when we started a pulse jet in the way described by Keith. It took 15 min to ignite the motor but then it worked fine. What a noise!!! The Germans had both the As044 and Jumo 226 pulsejets under development at the end of the war- both were investigated by the Russians from '45-'47. Rob Regards JasiekS Warsaw, Poland |
#22
|
|||
|
|||
"robert arndt" wrote in message om... Alan Minyard wrote in message . .. On 16 Jan 2004 22:22:15 -0800, (robert arndt) wrote: (WaltBJ) wrote in message . com... Eyeballing those pictures of the As044 and the Pabst ramjet - IMHO the AS044 is a pulse jet (else why the square grilled inlet?) and the Pabst ramjet is a neat way to convert fuel into smoke and noise. Its specific fuel consumption (Kg fuel/newton/hr) must have been very high indeed. I believe the ramjet fighter as pictured would have had a range even less than that of the Me163b. (Little volume for fuel.) Doubtless why it never made it off the sketch board. Walt BJ Walt, As for the Fw Ta 283 range question: the plane had enough fuel (1000+ liters) for 40 minutes of sustained flight. It's climb would have been around 17,500 fpm using the Walter rocket motor in the tail plus the two ramjets. So you would have less than two minutes of climb to get over the bomber stream and then dive down for the attack. I doubt the escort fighters would have been able to do anything about it until the Ta 283 had to land. More of the aircraft would have probably been lost to ground accidents as the Ta 283 had very narrow track landing gear. Rob Well, the V-1 used the same type of pulse jet, and they were routinely shot down. The pulse jet was a dead end technology. And it is NOT a form of "ram jet". Al Minyard snip Third, the pulsejet IS a form of ramjet, with intermittent combustion vs continuous. It cannot operate until it reaches a certain airspeed. In the Ta 283 this would be accomplished by the Walter rocket in the tail. Not true. Pulse jets can begin operation at zero-airspeed. Interesting photo of one doing so on this page: http://www.aardvark.co.nz/pjet/ I'd be reluctant to call a pulse jet a "form of ramjet", being as the latter DOES require tremendous forward airspeed and usually relies on no external ignition source for the development of thrust other than the compression of the airflow. Brooks Rob |
#24
|
|||
|
|||
"Kevin Brooks" wrote in message t...
"robert arndt" wrote in message om... Alan Minyard wrote in message . .. On 16 Jan 2004 22:22:15 -0800, (robert arndt) wrote: (WaltBJ) wrote in message . com... Eyeballing those pictures of the As044 and the Pabst ramjet - IMHO the AS044 is a pulse jet (else why the square grilled inlet?) and the Pabst ramjet is a neat way to convert fuel into smoke and noise. Its specific fuel consumption (Kg fuel/newton/hr) must have been very high indeed. I believe the ramjet fighter as pictured would have had a range even less than that of the Me163b. (Little volume for fuel.) Doubtless why it never made it off the sketch board. Walt BJ Walt, As for the Fw Ta 283 range question: the plane had enough fuel (1000+ liters) for 40 minutes of sustained flight. It's climb would have been around 17,500 fpm using the Walter rocket motor in the tail plus the two ramjets. So you would have less than two minutes of climb to get over the bomber stream and then dive down for the attack. I doubt the escort fighters would have been able to do anything about it until the Ta 283 had to land. More of the aircraft would have probably been lost to ground accidents as the Ta 283 had very narrow track landing gear. Rob Well, the V-1 used the same type of pulse jet, and they were routinely shot down. The pulse jet was a dead end technology. And it is NOT a form of "ram jet". Al Minyard snip Third, the pulsejet IS a form of ramjet, with intermittent combustion vs continuous. It cannot operate until it reaches a certain airspeed. In the Ta 283 this would be accomplished by the Walter rocket in the tail. Not true. Pulse jets can begin operation at zero-airspeed. Interesting photo of one doing so on this page: http://www.aardvark.co.nz/pjet/ I'd be reluctant to call a pulse jet a "form of ramjet", being as the latter DOES require tremendous forward airspeed and usually relies on no external ignition source for the development of thrust other than the compression of the airflow. Brooks Rob The Germans defined the ramjet as a propulsive duct or athodyd motor. The As044 is defined as an intermittent propulsive duct motor (translation: intermittent ramjet). - from "Jane's Fighting Aircraft of World War 2" Rob |
#25
|
|||
|
|||
"robert arndt" wrote in message m... "Kevin Brooks" wrote in message t... "robert arndt" wrote in message om... Alan Minyard wrote in message . .. On 16 Jan 2004 22:22:15 -0800, (robert arndt) wrote: (WaltBJ) wrote in message . com... Eyeballing those pictures of the As044 and the Pabst ramjet - IMHO the AS044 is a pulse jet (else why the square grilled inlet?) and the Pabst ramjet is a neat way to convert fuel into smoke and noise. Its specific fuel consumption (Kg fuel/newton/hr) must have been very high indeed. I believe the ramjet fighter as pictured would have had a range even less than that of the Me163b. (Little volume for fuel.) Doubtless why it never made it off the sketch board. Walt BJ Walt, As for the Fw Ta 283 range question: the plane had enough fuel (1000+ liters) for 40 minutes of sustained flight. It's climb would have been around 17,500 fpm using the Walter rocket motor in the tail plus the two ramjets. So you would have less than two minutes of climb to get over the bomber stream and then dive down for the attack. I doubt the escort fighters would have been able to do anything about it until the Ta 283 had to land. More of the aircraft would have probably been lost to ground accidents as the Ta 283 had very narrow track landing gear. Rob Well, the V-1 used the same type of pulse jet, and they were routinely shot down. The pulse jet was a dead end technology. And it is NOT a form of "ram jet". Al Minyard snip Third, the pulsejet IS a form of ramjet, with intermittent combustion vs continuous. It cannot operate until it reaches a certain airspeed. In the Ta 283 this would be accomplished by the Walter rocket in the tail. Not true. Pulse jets can begin operation at zero-airspeed. Interesting photo of one doing so on this page: http://www.aardvark.co.nz/pjet/ I'd be reluctant to call a pulse jet a "form of ramjet", being as the latter DOES require tremendous forward airspeed and usually relies on no external ignition source for the development of thrust other than the compression of the airflow. Brooks Rob The Germans defined the ramjet as a propulsive duct or athodyd motor. The As044 is defined as an intermittent propulsive duct motor (translation: intermittent ramjet). - from "Jane's Fighting Aircraft of World War 2" I guess all four folks who have corrected you are somehow wrong, eh? Who gives a rat's ass what the Germans "defined the ramjet as"? You said the pulse jet could not be operated "until it reaches a certain airspeed"...but the run them on test stands without a continuous pressurized air feed. "A pulse-jet engine delivers thrust at zero speed and can be started from rest..." (conceptengine.tripod.com/conceptengine/id17.html ), but the ramjet does indeed require a high inlet velocity for *both* startup and continuous operation. The ramjet has no need for moving parts--the old German pulse jets needed inlet and outlet valves (only later would the valveless pulse jet be developed, with little practical purpose demonstrated thus far). Oddly enough, the pulse jet can only operate up to around 600 mph; the ramjet can generally only operate *above* that speed. The German pulse jets, IIRC, required an ignition source; ramjets typically do not. Now what are all those reasons that you decided the pulse jet is a ramjet? Brooks Rob |
#26
|
|||
|
|||
"Kevin Brooks" wrote in message et...
"robert arndt" wrote in message m... "Kevin Brooks" wrote in message t... "robert arndt" wrote in message om... Alan Minyard wrote in message . .. On 16 Jan 2004 22:22:15 -0800, (robert arndt) wrote: (WaltBJ) wrote in message . com... Eyeballing those pictures of the As044 and the Pabst ramjet - IMHO the AS044 is a pulse jet (else why the square grilled inlet?) and the Pabst ramjet is a neat way to convert fuel into smoke and noise. Its specific fuel consumption (Kg fuel/newton/hr) must have been very high indeed. I believe the ramjet fighter as pictured would have had a range even less than that of the Me163b. (Little volume for fuel.) Doubtless why it never made it off the sketch board. Walt BJ Walt, As for the Fw Ta 283 range question: the plane had enough fuel (1000+ liters) for 40 minutes of sustained flight. It's climb would have been around 17,500 fpm using the Walter rocket motor in the tail plus the two ramjets. So you would have less than two minutes of climb to get over the bomber stream and then dive down for the attack. I doubt the escort fighters would have been able to do anything about it until the Ta 283 had to land. More of the aircraft would have probably been lost to ground accidents as the Ta 283 had very narrow track landing gear. Rob Well, the V-1 used the same type of pulse jet, and they were routinely shot down. The pulse jet was a dead end technology. And it is NOT a form of "ram jet". Al Minyard snip Third, the pulsejet IS a form of ramjet, with intermittent combustion vs continuous. It cannot operate until it reaches a certain airspeed. In the Ta 283 this would be accomplished by the Walter rocket in the tail. Not true. Pulse jets can begin operation at zero-airspeed. Interesting photo of one doing so on this page: http://www.aardvark.co.nz/pjet/ I'd be reluctant to call a pulse jet a "form of ramjet", being as the latter DOES require tremendous forward airspeed and usually relies on no external ignition source for the development of thrust other than the compression of the airflow. Brooks Rob The Germans defined the ramjet as a propulsive duct or athodyd motor. The As044 is defined as an intermittent propulsive duct motor (translation: intermittent ramjet). - from "Jane's Fighting Aircraft of World War 2" I guess all four folks who have corrected you are somehow wrong, eh? Who gives a rat's ass what the Germans "defined the ramjet as"? You said the pulse jet could not be operated "until it reaches a certain airspeed"...but the run them on test stands without a continuous pressurized air feed. "A pulse-jet engine delivers thrust at zero speed and can be started from rest..." (conceptengine.tripod.com/conceptengine/id17.html ), but the ramjet does indeed require a high inlet velocity for *both* startup and continuous operation. The ramjet has no need for moving parts--the old German pulse jets needed inlet and outlet valves (only later would the valveless pulse jet be developed, with little practical purpose demonstrated thus far). Oddly enough, the pulse jet can only operate up to around 600 mph; the ramjet can generally only operate *above* that speed. The German pulse jets, IIRC, required an ignition source; ramjets typically do not. Now what are all those reasons that you decided the pulse jet is a ramjet? Brooks Rob 1) I only said that the pulsejet was a FORM of ramjet (primitive at that) 2) the pulsejet is an athodyd (aero-thermodynamic-duct) motor also since it has no compressor nor turbine 3) the V-1 had to reach 250mph off the ramp for the pulsejet to operate independently, the V-4 with Pabst ramjet also was ramp-launched but with a rocket pod underneath the track to get it up to operating speed 4) main difference is only intermittent combustion vs continous combustion, otherwise they are two stovepipe engines 5) Valveless pulsejets were experimented with after the war, another athodyd Rob |
#27
|
|||
|
|||
On 18 Jan 2004 17:56:31 -0800, (robert arndt) wrote:
"Kevin Brooks" wrote in message t... "robert arndt" wrote in message om... Alan Minyard wrote in message . .. On 16 Jan 2004 22:22:15 -0800, (robert arndt) wrote: (WaltBJ) wrote in message . com... Eyeballing those pictures of the As044 and the Pabst ramjet - IMHO the AS044 is a pulse jet (else why the square grilled inlet?) and the Pabst ramjet is a neat way to convert fuel into smoke and noise. Its specific fuel consumption (Kg fuel/newton/hr) must have been very high indeed. I believe the ramjet fighter as pictured would have had a range even less than that of the Me163b. (Little volume for fuel.) Doubtless why it never made it off the sketch board. Walt BJ Walt, As for the Fw Ta 283 range question: the plane had enough fuel (1000+ liters) for 40 minutes of sustained flight. It's climb would have been around 17,500 fpm using the Walter rocket motor in the tail plus the two ramjets. So you would have less than two minutes of climb to get over the bomber stream and then dive down for the attack. I doubt the escort fighters would have been able to do anything about it until the Ta 283 had to land. More of the aircraft would have probably been lost to ground accidents as the Ta 283 had very narrow track landing gear. Rob Well, the V-1 used the same type of pulse jet, and they were routinely shot down. The pulse jet was a dead end technology. And it is NOT a form of "ram jet". Al Minyard snip Third, the pulsejet IS a form of ramjet, with intermittent combustion vs continuous. It cannot operate until it reaches a certain airspeed. In the Ta 283 this would be accomplished by the Walter rocket in the tail. Not true. Pulse jets can begin operation at zero-airspeed. Interesting photo of one doing so on this page: http://www.aardvark.co.nz/pjet/ I'd be reluctant to call a pulse jet a "form of ramjet", being as the latter DOES require tremendous forward airspeed and usually relies on no external ignition source for the development of thrust other than the compression of the airflow. Brooks Rob The Germans defined the ramjet as a propulsive duct or athodyd motor. The As044 is defined as an intermittent propulsive duct motor (translation: intermittent ramjet). - from "Jane's Fighting Aircraft of World War 2" Rob No one cares what the Nazis called it, they lost. It was not a ram jet. Al Minyard |
#28
|
|||
|
|||
On Sun, 18 Jan 2004 14:15:02 -0600, Alan Minyard
wrote: What current aircraft utilize a "pulse jet" engine?? A pulse jet is not, rpt not, a ram jet. look it up. You are 100% correct. Pulsejets use a completely different operating cycle to ramjets and have significantly different operating characteristics. Anyone seeking further clarification can check out these pages on my website: http://aardvark.co.nz/pjet/ramjets.htm and http://aardvark.co.nz/howtheywork.shtml -- you can contact me via http://aardvark.co.nz/contact/ |
#29
|
|||
|
|||
On 16 Jan 2004 22:11:46 -0800, (robert arndt) wrote:
A pulsejet is a form of ramjet except that the combustion is intermittent rather than continuous. The pulsejet uses spring loaded shutter valves that open and close for the imtermittent pulse... but is still a ramjet that has to be launched into the air by some means other than the engine for it to work. Not true at all. A properly designed pulsejet will run without forward movement through the air and produce static thrust in the process. The Argus V1 engine was designed to produce its maximum thrust at around 380mph which meant that its static thrust was about half the rated figure. The diffuser intake system was optimized for high-speed use so the engine was effectively somewhat choked at lower speeds. The reason the V1 used a launch ramp was because it was a craft with a decidedly poor power to weight ratio and a fairly high stall speed. This was mainly due to the high fuel load required to feed that gas-guzzling pulsejet engine. With all that weight of fuel onboard, plus a ton of HE, there's no way these things could have taken off under their own power in any sensible length of runway -- and besides which, the task of keeping them tracking straight during take-off would have required even more complexity in their design. A chemically powered launch ramp was a very practical solution to the problem -- although, having said that, a goodly number of V1s crashed reasonably close to the end of that ramp. I've got quite a bit of interesting footage of such events. -- you can contact me via http://aardvark.co.nz/contact/ |
#30
|
|||
|
|||
On Sun, 18 Jan 2004 12:20:55 +0100, "JasiekS"
wrote: A pulsejet motor can be started at ZERO ground speed when you supply sufficient airstream. Once started pusejet will wor fine when you cut this additional airstream. You can start ramjet in the same way, but when you stop auxillary airstream ramjet will cease to work. When in high school I attended two semesters of aeroengines. I recall one lesson when we started a pulse jet in the way described by Keith. It took 15 min to ignite the motor but then it worked fine. What a noise!!! You are correct -- but some pulsejets don't even require forced air to start. You can see a video of my self-starting pulsejet on my website by clicking on the link under all the flames at http://aardvark.co.nz/pjet/ -- you can contact me via http://aardvark.co.nz/contact/ |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Australia to participate in US missile defence program | David Bromage | Military Aviation | 40 | December 13th 03 01:52 PM |
AIM-54 Phoenix missile | Sujay Vijayendra | Military Aviation | 89 | November 3rd 03 09:47 PM |
Poland: French Missile Report Was Wrong | Michael Petukhov | Military Aviation | 8 | October 7th 03 10:54 PM |
Surface to Air Missile threat | PlanetJ | Instrument Flight Rules | 1 | August 14th 03 02:13 PM |
Rafael's AIM-AIR IR Missile Countermeasure | JT | Military Aviation | 8 | July 13th 03 03:41 AM |