Would this work? Project: BenJet XL 0.1

Moderator: Mike Everman

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Would this work? Project: BenJet XL 0.1

Post by BenJet » Wed Feb 10, 2010 5:32 pm

One little introduction:

Hello everyone, I am new to the forums. And this is my first post. :roll: I accidentally found the PulseJet Engine by actually googling for an Yamaha motorbike I wanted to buy. :oops: Afterward I started looking at (I can't remember how many) youtube videos and I found this so interesting that I first canceled buying this motorbike and investigate more about this fabulous old technology. I'm glad that the Germans found some use (not a very humanitarian use at all :shock: ) to it and made it popular. Now I am hooked to it. :D

About the project:
So, I've been looking around. Taking notes, writing down useful tips I've found over the net. And keeping ideas of other people's PulseJets (thanks for all the videos and info that is being shared).

I started drawing some PulseJet... Some might work, some might not. One of them I am going to show you now...

Here are the plans:

As you can see. The air enters in the front, so that the (4) air intakes can get some fresh air, the (10) augmentators over them will contribute to thrust, rest air will cool the components inside flowing around the (5) chamber and the (6) exhaust finally exiting the (8) overair/cooling whatever u wanna call em holes. (13) could be some sort of heat resistant noise damping material. fuel is being heated before it enters the combustion chamber :wink:

Image

Front and back view.

Image

Looking forward to read some tips and suggestions, or just read what you think about this project. I am not even sure if this will work. I really would like to build some kind of engine I could use to attack it to something. Still looking where I can get good materials (still not sure what to use) and someone who has the machinery to help with bending tubes and all that stuff.

Thanks
Ben
Everman, give us forum avatars!

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Re: Would this work? Project: BenJet XL 0.1

Post by BenJet » Wed Feb 10, 2010 9:07 pm

Any ideas? or is this thing completely useless as "propulsion engine" ?
Everman, give us forum avatars!

Johansson
Posts: 1161
Joined: Sun Nov 21, 2004 9:42 pm
Antipspambot question: 0
Location: Northern Sweden

Re: Would this work? Project: BenJet XL 0.1

Post by Johansson » Wed Feb 10, 2010 9:56 pm

Hi and welcome to the forum!

No offence but you just made the "Beginner Mistake 1A" by starting to figure out a groundbreaking new and completely untried engine without any previous experience. I´ve seen it on many different forums and I´ve made it myself once or twice before I started reading up on the subject. :mrgreen:

Without anything to say about the engine design you posted I think that your first step should be to read the stickys and find out more about pulsejet engines, then select a simple valveless engine like the FWE, a pipejet or any other simple engine that you can build with the tools you have at home. When you have gained some experience and run time you can give your engine a go, but to start with such a project now would be a one way road towards failure I think.

hinote
Posts: 1241
Joined: Sat Oct 04, 2003 1:54 am
Antipspambot question: 0
Location: Central California

Re: Would this work? Project: BenJet XL 0.1

Post by hinote » Wed Feb 10, 2010 10:41 pm

Johansson wrote:Hi and welcome to the forum!

No offence but you just made the "Beginner Mistake 1A" by starting to figure out a groundbreaking new and completely untried engine without any previous experience. I´ve seen it on many different forums and I´ve made it myself once or twice before I started reading up on the subject. :mrgreen:
Hello:

I second Johansson's remarks here; a good way to approach something as complex as a good-running pulsejet is to say to yourself, "if it hasn't already been done it probably CAN'T be done either!"

To answer your question more specifically, contained pulsejets usually don't work because the outer shroud interferes with the acoustics that operate the motor. I believe that either SNECMA or Lockwood found that a volume of something like 50x that of the motor was necessary in the outer shroud to reduce this effect--making it essentially useless.

Bill

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Re: Would this work? Project: BenJet XL 0.1

Post by BenJet » Wed Feb 10, 2010 11:49 pm

Thanks a lot for your answers, It's good, I accept critics if they help to improve. You probably saved me some money too, I did not know that putting a pulse engine in a enclosure would harm its functioning.

I was already working on a new project, but now I will do as you say. But starting with an Ecrevisse/Lockwood, I want something that blows.

Even if its useless I uploaded the pics of what I was doing just in case someone was interested. Maybe I give someone ideas... who knows.

The idea was to put 4 Ecrevisse/Lockwood engines into one enclosure.

The beginning of a new engine.
Image

The big air intake.
Image

The internals, I wanted to make a quad Ecrevisse engine. You can see combustion chamber (i was about to make it bigger), and air intakes. and the exhaust pipe part. curve part is missing.
Image

The back with all exhaust.
Image

Thanks for the info, as I said before.
Im going to start small like you advised.

EDIT: But I'm definitely going to build something like this sometime this year (after experimenting with single ones), even if its going to be a big FAIL. The best thing to see if it works if doing it :lol:

Thanks
Ben
Everman, give us forum avatars!

Johansson
Posts: 1161
Joined: Sun Nov 21, 2004 9:42 pm
Antipspambot question: 0
Location: Northern Sweden

Re: Would this work? Project: BenJet XL 0.1

Post by Johansson » Thu Feb 11, 2010 8:39 am

BenJet wrote:But I'm definitely going to build something like this sometime this year (after experimenting with single ones), even if its going to be a big FAIL. The best thing to see if it works if doing it :lol:
That´s the spirit! :D

It makes wonders for the confidence to build an engine that is known to work first before you start on a project of that magnitude, the worst scenario is that you only get loads of flames and a couple of bangs and then it is great to have a working engine that can cheer you up again before you start building the BenJet MK2.

Viv
Posts: 2158
Joined: Sat Oct 04, 2003 2:35 pm
Antipspambot question: 125
Location: Normandy, France, Wales, Europe
Contact:

Re: Would this work? Project: BenJet XL 0.1

Post by Viv » Thu Feb 11, 2010 2:27 pm

Hi Ben

I like the creativity you are bringing to the subject, that is to be encouraged I think but also tempered by the experience you will find here on the forum, that experience and knowledge will save you going down some dead ends and wasting time and money.

Think about your engine core as an acoustic resonator (musical instrument) that is powered by the heat release of the burning fuel (that's ya thermobollocks bit), now looking at your design I would ask you to think about how the shroud would make the sound change and how the heat release from the burning fuel would be affected, those are some of the key factors.

As Anders and Bill suggest, try building a smaller engine from a known good set of plans and get some hands on experience, it will help you a lot with your designs.

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

Viv's blog

Monsieur le commentaire

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Re: Would this work? Project: BenJet XL 0.1

Post by BenJet » Thu Feb 11, 2010 11:20 pm

Johansson wrote:
BenJet wrote:But I'm definitely going to build something like this sometime this year (after experimenting with single ones), even if its going to be a big FAIL. The best thing to see if it works if doing it :lol:
That´s the spirit! :D

It makes wonders for the confidence to build an engine that is known to work first before you start on a project of that magnitude, the worst scenario is that you only get loads of flames and a couple of bangs and then it is great to have a working engine that can cheer you up again before you start building the BenJet MK2.
Haha, yeah. But well, if everything goes right soon you will see the BenJet MK3/Blaster. If it works or not :P
Viv wrote:Hi Ben

I like the creativity you are bringing to the subject, that is to be encouraged I think but also tempered by the experience you will find here on the forum, that experience and knowledge will save you going down some dead ends and wasting time and money.

Think about your engine core as an acoustic resonator (musical instrument) that is powered by the heat release of the burning fuel (that's ya thermobollocks bit), now looking at your design I would ask you to think about how the shroud would make the sound change and how the heat release from the burning fuel would be affected, those are some of the key factors.

As Anders and Bill suggest, try building a smaller engine from a known good set of plans and get some hands on experience, it will help you a lot with your designs.

Viv
Hey Viv, thanks for your answer.

I am working on "another" :roll: new design that makes more sense and does not require much materials at all. The good thing is that I found some guys over here (Lanzarote, Canary Islands. Spain) that are willing to help with bending tubes (I don't have the machinery) and cutting and soldering, another guy who donated his motorbike so I have already a vehicle to attach it to :D :D

I will create a new post when "we" (now that we are a little group) finish building this engine, will take a lot of pictures with my d.reflex cam of the assembly and luckily hd videos if a mate of mine lends me his fullhd video recorder. :o

By the way, I've never seen anyone using a "decent" :) control panel for their PulseJets, here is the one I'm going to build for my testings.

Image
There still a lot of things to improve, like 2 pressure gauges, one before throttle control and another one after. Or one pump for each fuel connection. Etc..
Maybe you even wanna put a solar panel in the optional section :P

Things are getting started... I'm exited. :D :D :D

Just noticed at a mates house, that the pictures of the previous posts are not shown completely for people with lower resolutions, right click and "view image" for complete pic.

Greets
Ben
Everman, give us forum avatars!

Kool
Posts: 115
Joined: Wed Oct 01, 2008 7:39 pm
Antipspambot question: 125
Location: The Netherlands

Re: Would this work? Project: BenJet XL 0.1

Post by Kool » Fri Feb 12, 2010 9:53 am

I am inquisitive, it seems that you gonna be seriously :)

On the second sketchup drawing it seems to me that you using a converging cone(reducer?). Probably you have copied this from turbine engines. This is not very common with pulse-jets. Although I am not very experienced with pulse-jets, I think it is better to use an so called augmentor/ejector. How this will work can be read here http://www.aardvark.co.nz/pjet/augmentors.shtml
...It's better to generate heat efficiently, than recover it efficiently...

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Re: Would this work? Project: BenJet XL 0.1

Post by BenJet » Fri Feb 12, 2010 1:54 pm

poech prut wrote:I am inquisitive, it seems that you gonna be seriously :)

On the second sketchup drawing it seems to me that you using a converging cone(reducer?). Probably you have copied this from turbine engines. This is not very common with pulse-jets. Although I am not very experienced with pulse-jets, I think it is better to use an so called augmentor/ejector. How this will work can be read here http://www.aardvark.co.nz/pjet/augmentors.shtml
Thanks for your interest, I've not progressed with this particular design since I'm working on something smaller as some people have recomended to start with.

The final version should have looked somehow like this inside, you have to put a little imagination tho. Its 4x Lockwoods in one enclosure.
Image

I am currently gathering the eletric parts for the ignition/control station for the "new" design, you will like that one better. Yesterday at 4am I finished the measurements plan for all the pieces. The name of this project is hopefully: BenJet Beast. If it complies with what it promises. PulseJet Engine with fly direction air intake, you will see...

Greets
Ben
Everman, give us forum avatars!

Viv
Posts: 2158
Joined: Sat Oct 04, 2003 2:35 pm
Antipspambot question: 125
Location: Normandy, France, Wales, Europe
Contact:

Re: Would this work? Project: BenJet XL 0.1

Post by Viv » Fri Feb 12, 2010 2:31 pm

Hi Ben

Here's some thing for you to read ;-)

Viv
Attachments
05189875_001.pdf
(574.39 KiB) Downloaded 270 times
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

Viv's blog

Monsieur le commentaire

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Re: Would this work? Project: BenJet XL 0.1

Post by BenJet » Fri Feb 12, 2010 5:31 pm

Viv wrote:Hi Ben

Here's some thing for you to read ;-)

Viv
That is a nice piece of engineering, but it has one problem. :twisted:

It is has moving parts! That's a pain in the ass to change valves every x times. And personally I think I could not afford making that engine out of complete stainless steel or titanium. Because I will not work my ass off in designing/building an engine with crappy materials and see it engulfed in flames the first day of usage! Because I'm going to pwn it with massive fuel! And it must withstand. :D :lol: :lol:

I have to go to Switzerland in March and visit the parents of my girlfriend :shock: ... That money could have been inverted buying some nice stainless steel plates for my current project. :D :lol:

The start of building of the current project will be delayed 5 days, because one of the team members (one of the the metal guys) had to leave to France. He will come back next Friday :cry: . Patience, my friend... patience. I do not have patience!!!! Well at least I have time to finish the control panel :)

No, seriously now. Building that thing is over my level and possibilities, it was a nice read and it might help me for future projects. But now, wait until I get my current project done. :P

Greets
Ben
Everman, give us forum avatars!

Jutte
Posts: 332
Joined: Wed Aug 22, 2007 11:01 am
Antipspambot question: 0
Location: NZ

Re: Would this work? Project: BenJet XL 0.1

Post by Jutte » Fri Feb 12, 2010 11:59 pm

OK - wrote a big reply but my computer ate it - so will give it another go.
Just a few ideas...for the sake of the following consider a basic straight pulse jet - not a folded one.
OK - its a given that an outer shroud casing will stuff up the acoustics etc.
But what if you "retune'( shorten) the tail pipe so it resonates within the shroud
and still runs - ( a problem would be the returning hot gas piston - enough to produce thrust
within the shroud and enough to return for reignition etc...and what to do with the intake etc)?
In one of my experiments I sucessfully ran an enclosed shroud without retuning of the pulse jet.
The experiments had nothing to do with what Ben suggested but they were successful ( yes you can silence/quieten
a pulse jet to keep neighbours happy - the good wife happy ...the mother inlaw relatively impressed AND happy
{bonus points there guys} :lol: )
Another idea - why not a preforated barrier ( eg: as in a rijks tube but axially) that the pulse
jet sees it as a 'resonance barrier' but still enables the use of an outer shroud as Ben suggests.
I can't really do much experimentation now as I have recently rejoined the student world - and with
a family it changes things a bit.
However still managed to fire up the LPG Cylinder quiet pulse jet so the kids could toast
marshmellows . :D
OK just ideas - feel free to shoot down etc.

Viv
Posts: 2158
Joined: Sat Oct 04, 2003 2:35 pm
Antipspambot question: 125
Location: Normandy, France, Wales, Europe
Contact:

Re: Would this work? Project: BenJet XL 0.1

Post by Viv » Sat Feb 13, 2010 1:40 am

BenJet wrote:
Viv wrote:Hi Ben

Here's some thing for you to read ;-)

Viv
That is a nice piece of engineering, but it has one problem. :twisted:

It is has moving parts! That's a pain in the ass to change valves every x times. And personally I think I could not afford making that engine out of complete stainless steel or titanium. Because I will not work my ass off in designing/building an engine with crappy materials and see it engulfed in flames the first day of usage! Because I'm going to pwn it with massive fuel! And it must withstand. :D :lol: :lol:

I have to go to Switzerland in March and visit the parents of my girlfriend :shock: ... That money could have been inverted buying some nice stainless steel plates for my current project. :D :lol:

The start of building of the current project will be delayed 5 days, because one of the team members (one of the the metal guys) had to leave to France. He will come back next Friday :cry: . Patience, my friend... patience. I do not have patience!!!! Well at least I have time to finish the control panel :)

No, seriously now. Building that thing is over my level and possibilities, it was a nice read and it might help me for future projects. But now, wait until I get my current project done. :P

Greets
Ben
Hi Ben

The general idea was to give you a pointer towards the USPTO office and their very excellent search function, you can spend many happy hours there researching what has already been published on the subject ;-)

Melenric is a good place to start but try Dunbar and Bodine too ;-)

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

Viv's blog

Monsieur le commentaire

BenJet
Posts: 33
Joined: Wed Feb 10, 2010 4:59 pm
Antipspambot question: 125
Location: Spain

Re: Would this work? Project: BenJet XL 0.1

Post by BenJet » Sat Feb 13, 2010 5:25 pm

Okay guys, this is some serious piece of art. :twisted: :twisted: :twisted:

It's name is: BenJet - The Beast.

I thought to wait until the construction of this engine is done before publishing the plans. But for now I let you have a sneak peak of the current design. :)

The engine is 1,60 meters (59 inches) long and has an max diameter of 30cm (11,8 inches) at the combustion chamber.
The fuel pipe goes from the back top of the through the chamber. But I don't know how to make that damn wielding in Sketch-up. :roll:
Multiple intake design to enrich the fuel with air, and flame holder is missing right after the air intake that is attached to the cc, to be designed...
Image

Glad I wanted to start with a small project.

Info: If you don't see the whole picture, right click and "View Image" in Firefox.

Greets
Ben
Everman, give us forum avatars!

Post Reply