I have just refilled my tank but I don't think I am getting full pressure out of it because when I went to get it filled the guy messed up or something because it took forever to fill and acted like it needed to be re-purged.
I have most standard sizes of brake line from 1/16, 1/8, 3/16 and 1/4. But it is easy to change the diameter with a drill. I have a rig that clamp on the exhaust pipe and allows me full freedom to how deep the injectors go. I am going to put airlines on the set up as well to ease starting.
Thanks for the help and can't wait to see the new design. I hope you will also post information on the new design as well. I will surely have to build it. Every jet I build seems to look nicer then the last so I can't wait.
Nanosoft
Nanosoft: New Chinese Project
Moderator: Mike Everman
-
milisavljevic
- Posts: 855
- Joined: Sat Oct 04, 2003 9:36 am
- Antipspambot question: 125
re: Nanosoft: New Chinese Project
Hello Mikhail,
That is great news about your adjustable fueling rig. I think that you will find that optimum injector placement is a function
of not only engine type (e.g., Chinese, Escopeta or Lockwood), but also the characteristics of the engine itself (e.g., peak
pressure ratio across the inlet plane, operating frequency, etc.). In other words, given two similar engines, e.g., Chinese,
injector placement will be the same at a coarse level (e.g., intake-fed), but different at a fine level (e.g., feed depth 15%
versus 25%) due to small differences in the two ducts' internal characteristics. This implies that fuel injection is properly
considered as part of a duct's overall "tuning"; in fact, it may be the only type of post-construction tuning ever needed.
I will perform a preliminary sizing for your injectors, based upon the anticipated performance of your revised duct. Thrust
is expected to top out at 5 kgf, at a SFC of 2.3-3.0 kg/kgf/hr; therefore, maximum fuel flow should be less than 15 kg/hr.
Of course, I do not recommend that you run continuously at full throttle! "Typical" fuel flow may be be calculated, by the
use of a slightly lower thrust setting, e.g., 4.5 kgf * 2.2-2.4 kg/kgf/hr = approx. 10-11 kg/hr. I will post the results later.
With respect to the new engine, I will post explanatory text, and answer any questions - if I know the answers. The new
duct is an extension from your original, where all dimensions were permitted to change in order to optimise performance.
I simply attempted to find out just how much thrust may be extracted from a twin-intake Chinese-type duct, constrained
to an overall legth of 838 mm (33 inches), while retaining good-to-excellent acoustic performance, at an acceptable SFC.
Best regards,
Störgröße M.
__________________
Doughboy writes, "Be civil, or be gone." To which I say, "Put up, or shut up." Oh, to hear the jackboots of our pink dictator!
That is great news about your adjustable fueling rig. I think that you will find that optimum injector placement is a function
of not only engine type (e.g., Chinese, Escopeta or Lockwood), but also the characteristics of the engine itself (e.g., peak
pressure ratio across the inlet plane, operating frequency, etc.). In other words, given two similar engines, e.g., Chinese,
injector placement will be the same at a coarse level (e.g., intake-fed), but different at a fine level (e.g., feed depth 15%
versus 25%) due to small differences in the two ducts' internal characteristics. This implies that fuel injection is properly
considered as part of a duct's overall "tuning"; in fact, it may be the only type of post-construction tuning ever needed.
I will perform a preliminary sizing for your injectors, based upon the anticipated performance of your revised duct. Thrust
is expected to top out at 5 kgf, at a SFC of 2.3-3.0 kg/kgf/hr; therefore, maximum fuel flow should be less than 15 kg/hr.
Of course, I do not recommend that you run continuously at full throttle! "Typical" fuel flow may be be calculated, by the
use of a slightly lower thrust setting, e.g., 4.5 kgf * 2.2-2.4 kg/kgf/hr = approx. 10-11 kg/hr. I will post the results later.
With respect to the new engine, I will post explanatory text, and answer any questions - if I know the answers. The new
duct is an extension from your original, where all dimensions were permitted to change in order to optimise performance.
I simply attempted to find out just how much thrust may be extracted from a twin-intake Chinese-type duct, constrained
to an overall legth of 838 mm (33 inches), while retaining good-to-excellent acoustic performance, at an acceptable SFC.
Best regards,
Störgröße M.
__________________
Doughboy writes, "Be civil, or be gone." To which I say, "Put up, or shut up." Oh, to hear the jackboots of our pink dictator!
-
milisavljevic
- Posts: 855
- Joined: Sat Oct 04, 2003 9:36 am
- Antipspambot question: 125
re: Nanosoft: New Chinese Project
Hello Mikhail,
Here are the suggested sizes for your fuel injectors. The unknowns here are: (a) the pressure in your propane bottle;
and (b) the ambient temperature. There is also the question of using each tube for direct injection, or drilling smaller
holes in each tube, and then sealing off the ends, i.e., "swizzle sticks". So, I have included "advice" about this type.
Please note that the attached "advice" is specifically intended, i.e., sized, for your current project. I hope this helps.
My recommendation is that you keep it simple, and use direct injection, i.e., one (1) opening at the end of each tube.
BTW, I have the drawing ready for the improved duct; I just need to find time to write up the explanatory text for you!
Best regards,
Störgröße M.
__________________
Doughboy writes, "Be civil, or be gone." To which I say, "Put up, or shut up." Oh, to hear the jackboots of our pink dictator!
Here are the suggested sizes for your fuel injectors. The unknowns here are: (a) the pressure in your propane bottle;
and (b) the ambient temperature. There is also the question of using each tube for direct injection, or drilling smaller
holes in each tube, and then sealing off the ends, i.e., "swizzle sticks". So, I have included "advice" about this type.
Please note that the attached "advice" is specifically intended, i.e., sized, for your current project. I hope this helps.
My recommendation is that you keep it simple, and use direct injection, i.e., one (1) opening at the end of each tube.
BTW, I have the drawing ready for the improved duct; I just need to find time to write up the explanatory text for you!
Best regards,
Störgröße M.
__________________
Doughboy writes, "Be civil, or be gone." To which I say, "Put up, or shut up." Oh, to hear the jackboots of our pink dictator!
Last edited by milisavljevic on Sat Dec 31, 2005 3:23 pm, edited 1 time in total.
-
milisavljevic
- Posts: 855
- Joined: Sat Oct 04, 2003 9:36 am
- Antipspambot question: 125
An enhanced, twin-intake Chinese-type pulsejet
Hello Mikhail!
Here it is, the dimensioned drawing that I had promised to post. Please note, that there are four (4) pulsejets depicted:
1. Your "original", twin-intake, Chinese-type pulsejet;
2. The revised version that you now have under test;
3a. and 3b. "Enhanced" models, fully re-dimensioned, and optimised to develop the maximum sustainable thrust output.
(note: the only difference between 3a. and 3b., is that version 3b. features a constant diameter "straightaway", and so
will be somewhat easier to fabricate; however, an expanding straightaway is preferable, as dimensioned in version 3a.)
In the spirit of Next Year's forthcoming "Great Chinese Pulsejet Shootout", I first followed your performance weightings:
(a) highest weighting - develop maximum static thrust;
(b) second weighting - incorporate optimum acoustics;
(c) last weighting - minimum specific fuel consumption.
However, the physics of better pulsejet design dictate that items (a) and (b) exchange positions, thus making the goal
to obtain maximum sustainable thrust from a well-balanced, smooth-running duct. After all, if the acoustics are "hash",
then the result is either a duct that will not self-sustain, or a noisy, under-performing duct, destined for the scrap heap.
The limiting constraint, as given in this contest's ad-hoc rules, is the maximum allowable length of 838 mm (33 inches).
This will then constrain the tailpipe's effective length-to-diameter ratio, and therefore, its maximum diameter and profile.
Of course, these limits will in turn constrain fore and aft pressure biases, and therefore, reduce maximum static thrust.
Given that your original layout was a twin-intake Chinese-type pulsejet, I had hoped to attain an integer thrust multiple
of the "classic" Chinese-type pulsejet, first popularised on this forum from an inaccurate schematic, drawn by DE Laird.
The "Laird" Chinese can develop about 2.0 kilograms of thrust; therefore, a 3x or 4x OA improvement looked attractive;
however, 3x (6 kgf) was too easily attained, and 4x (8 kgf) looks a bit dicey with respect to the tailpipe's acoustics, so
I finally settled for the design attached below: a 3.5x improvement over the "Laird" Chinese that develops a full 7.0 kgf.
(note: if the 5.0 kgf revision that you now have under test is _completely_ successful, then I will re-attempt the 4x goal)
Here are more of the calculated performance specifications, in addition to maximum static thrust, for ICAO standard day:
(a) maximum continuous static thrust rating > 7.0 kgf (15.5 lbf);
(b) fore-aft thrust distribution at maximum thrust = 24% x 76%;
(c) characteristic resonant frequency = 282 Hz (+/- 2, at 600 K);
(d) primary acoustics suite: n1, e2, and e3 = 5:1, 4:3, and 15:1;
(e) step ratio and forward pressure bias: s1, s2 = 2.7 and 1.55;
and last, but not least... (f) SFC = 1.85 < wf < 2.45 kg/kgf/hr, at maximum thrust (equivalence ratio = 0.95 < ER < 1.30).
(a lower SFC was possible; however, the primary goal was to extract maximum thrust, and not maximum fuel economy)
Of course, if anyone else wishes to build this pulsejet, for amusement and|or testing, please do so. To the extent of my
time and ability to answer questions, I will. However, only serious builders will receive serious answers; no bait-cutters.
And lest I forget... HAPPY NEW YEAR!!!
Best regards,
Störgröße M.
__________________
"Back of the envelope calculation? Try a back, front, and inside-out of the envelope calculation. Or a napkin." -- Störgröße M.
Here it is, the dimensioned drawing that I had promised to post. Please note, that there are four (4) pulsejets depicted:
1. Your "original", twin-intake, Chinese-type pulsejet;
2. The revised version that you now have under test;
3a. and 3b. "Enhanced" models, fully re-dimensioned, and optimised to develop the maximum sustainable thrust output.
(note: the only difference between 3a. and 3b., is that version 3b. features a constant diameter "straightaway", and so
will be somewhat easier to fabricate; however, an expanding straightaway is preferable, as dimensioned in version 3a.)
In the spirit of Next Year's forthcoming "Great Chinese Pulsejet Shootout", I first followed your performance weightings:
(a) highest weighting - develop maximum static thrust;
(b) second weighting - incorporate optimum acoustics;
(c) last weighting - minimum specific fuel consumption.
However, the physics of better pulsejet design dictate that items (a) and (b) exchange positions, thus making the goal
to obtain maximum sustainable thrust from a well-balanced, smooth-running duct. After all, if the acoustics are "hash",
then the result is either a duct that will not self-sustain, or a noisy, under-performing duct, destined for the scrap heap.
The limiting constraint, as given in this contest's ad-hoc rules, is the maximum allowable length of 838 mm (33 inches).
This will then constrain the tailpipe's effective length-to-diameter ratio, and therefore, its maximum diameter and profile.
Of course, these limits will in turn constrain fore and aft pressure biases, and therefore, reduce maximum static thrust.
Given that your original layout was a twin-intake Chinese-type pulsejet, I had hoped to attain an integer thrust multiple
of the "classic" Chinese-type pulsejet, first popularised on this forum from an inaccurate schematic, drawn by DE Laird.
The "Laird" Chinese can develop about 2.0 kilograms of thrust; therefore, a 3x or 4x OA improvement looked attractive;
however, 3x (6 kgf) was too easily attained, and 4x (8 kgf) looks a bit dicey with respect to the tailpipe's acoustics, so
I finally settled for the design attached below: a 3.5x improvement over the "Laird" Chinese that develops a full 7.0 kgf.
(note: if the 5.0 kgf revision that you now have under test is _completely_ successful, then I will re-attempt the 4x goal)
Here are more of the calculated performance specifications, in addition to maximum static thrust, for ICAO standard day:
(a) maximum continuous static thrust rating > 7.0 kgf (15.5 lbf);
(b) fore-aft thrust distribution at maximum thrust = 24% x 76%;
(c) characteristic resonant frequency = 282 Hz (+/- 2, at 600 K);
(d) primary acoustics suite: n1, e2, and e3 = 5:1, 4:3, and 15:1;
(e) step ratio and forward pressure bias: s1, s2 = 2.7 and 1.55;
and last, but not least... (f) SFC = 1.85 < wf < 2.45 kg/kgf/hr, at maximum thrust (equivalence ratio = 0.95 < ER < 1.30).
(a lower SFC was possible; however, the primary goal was to extract maximum thrust, and not maximum fuel economy)
Of course, if anyone else wishes to build this pulsejet, for amusement and|or testing, please do so. To the extent of my
time and ability to answer questions, I will. However, only serious builders will receive serious answers; no bait-cutters.
And lest I forget... HAPPY NEW YEAR!!!
Best regards,
Störgröße M.
__________________
"Back of the envelope calculation? Try a back, front, and inside-out of the envelope calculation. Or a napkin." -- Störgröße M.
re: Nanosoft: New Chinese Project
Today I will do some more testing. I am sure that it will run with a little work. Hopefully all will go well. I post pictures later.
The new design looks awesome. I will start construction probably next week. I think I am going to go buy some stainless sheet to build this new one because I am running out. What thickness do people recommend? I have never bought any before I just use what I find laying around which is usually pretty thick (.035 inches or .9mm).
Nanosoft
The new design looks awesome. I will start construction probably next week. I think I am going to go buy some stainless sheet to build this new one because I am running out. What thickness do people recommend? I have never bought any before I just use what I find laying around which is usually pretty thick (.035 inches or .9mm).
Nanosoft
-
Mike Everman
- Posts: 5007
- Joined: Fri Oct 31, 2003 7:25 am
- Antipspambot question: 0
- Location: santa barbara, CA
- Contact:
re: Nanosoft: New Chinese Project
go guys! Faaaascinating. May all your predictions be true, M.
I'd stick with the .035 material personally. It's got the right mix of formability/weldability/snippability.
I'd stick with the .035 material personally. It's got the right mix of formability/weldability/snippability.
Mike Often wrong, never unsure.
__________________________
__________________________
-
milisavljevic
- Posts: 855
- Joined: Sat Oct 04, 2003 9:36 am
- Antipspambot question: 125
re: Nanosoft: New Chinese Project
I would take Mike's recommendation. Bill Hinote has had a lot of success with mild-steel sheet in the 0.030-0.035 inch range.
Obviously, 0.035 inch stainless will be better than mild-steel in this type of application. You can always go "thinner" later on.
Please, let's get your current engine proved out before you move on to the next one! There's real learning to be had there.
Have a happy and safe New Year's Eve, one and all.
Best regards,
Störgröße M.
__________________
"Back of the envelope calculation? Try a back, front, and inside-out of the envelope calculation. Or a napkin." -- Störgröße M.
Obviously, 0.035 inch stainless will be better than mild-steel in this type of application. You can always go "thinner" later on.
Please, let's get your current engine proved out before you move on to the next one! There's real learning to be had there.
Have a happy and safe New Year's Eve, one and all.
Best regards,
Störgröße M.
__________________
"Back of the envelope calculation? Try a back, front, and inside-out of the envelope calculation. Or a napkin." -- Störgröße M.
-
milisavljevic
- Posts: 855
- Joined: Sat Oct 04, 2003 9:36 am
- Antipspambot question: 125
Request for sound file.
Hello Mikhail,
I have a request for you: before you complete whatever tasks may be necessary to bring your revised duct to self-sustaining
operation, please close off an inlet, and use an air source to bring the duct into resonance, just as you did with your original.
Make a sound recording of the engine, again, just as you did before, and then post the file to this thread. Please include the following information, if available: (a) temperature; (b) air pressure; and (c) humidity at your test site (a local airport will do).
This information will be quite helpful, as I can "drop" it directly into my model, and then compare it to the original simulations.
This will also help me evaluate the enhanced duct that I posted yesterday; it will be interesting to see if it needs another go.
Thank you in advance!
Best regards,
Störgröße M.
__________________
"Back of the envelope calculation? Try a back, front, and inside-out of the envelope calculation. Or a napkin." -- Störgröße M.
I have a request for you: before you complete whatever tasks may be necessary to bring your revised duct to self-sustaining
operation, please close off an inlet, and use an air source to bring the duct into resonance, just as you did with your original.
Make a sound recording of the engine, again, just as you did before, and then post the file to this thread. Please include the following information, if available: (a) temperature; (b) air pressure; and (c) humidity at your test site (a local airport will do).
This information will be quite helpful, as I can "drop" it directly into my model, and then compare it to the original simulations.
This will also help me evaluate the enhanced duct that I posted yesterday; it will be interesting to see if it needs another go.
Thank you in advance!
Best regards,
Störgröße M.
__________________
"Back of the envelope calculation? Try a back, front, and inside-out of the envelope calculation. Or a napkin." -- Störgröße M.
re: Nanosoft: New Chinese Project
Well sorry for the wait. It will be a little longer; life keeps getting in the way. I am doing last minute college apps and lots of studying for finals. I have lots of projects to work on and I will get back to pulsejets when I have time. At the moment I have my motorcycle stripped to the fame for painting cleaning and adjusting for a big motorcycle race. I also have been doing lots of work on my truck (Installing Banks Turbo and Exhaust system, Add-a-leaf kit, and other misc. things). I will post more info relating to jets when I get some more testing done.
Nanosoft
Nanosoft