Jam Jar Car Fun

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Jam Jar Car Fun

Post by PyroJoe » Mon Jan 03, 2011 2:39 pm

Hi all,
Was lucky enough to find someone willing to allow a few runs in their facility. We had to run the AC to reduce the temperature from 76 down to 70 degrees F. (Yes it was 76 degrees here on Dec. 31!)

The runs were a little over sixty feet.
Probably had enough fuel remaining to go twice this distance.
Used cardboard insulation/cradle to keep the combustor from melting the plastic vehicle. ha

Weight is a important design note, as well as airflow, both the vehicle and cradle have multiple holes cut out. Almost a swiss cheese effect.

3" diameter combustor has a steel bottom and aluminum top glued together with automotive black RTV silicone.

http://www.youtube.com/watch?v=tvfF-6Atz4A

http://www.youtube.com/watch?v=FuTUc3D5mFQ

good fun, hope everyone has a great new year!

Mark
Posts: 10692
Joined: Sat Oct 11, 2003 10:14 pm

Re: Jam Jar Car Fun

Post by Mark » Wed Jan 05, 2011 12:04 am

Not bad. Cute design too. Interesting in the second video how the initial whoosh provides no real thrust but the reving that follows does. I like the first few revs, how they speed the car up in pulses. Definitely entertaining. Clever about the air conditioning factor, I can relate to that.
Presentation is Everything

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Jam Jar Car Fun

Post by PyroJoe » Wed Jan 05, 2011 5:45 pm

Yeh, that slow run I didn't let it recover completely from a previous run, the mild initial whoosh setup up a reduced cycle. It finally started building during the last 3 or 4 feet of the run.

I wish I could find several hundred feet of runway. :wink:

As the fuel is used up the car becomes lighter and there is a stronger cycle, just as the last of the fuel pool is turned to vapor.

Mike Everman
Posts: 4894
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Jam Jar Car Fun

Post by Mike Everman » Sat Jan 08, 2011 5:26 am

Those vids are so fun!
First one to make a helicopter wins!
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

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

Re: Jam Jar Car Fun

Post by Johansson » Sat Jan 08, 2011 9:08 am

Ha ha, great fun! :D

ganuganu
Posts: 340
Joined: Tue Dec 14, 2010 7:31 am
Antipspambot question: 125
Location: india
Contact:

Re: Jam Jar Car Fun

Post by ganuganu » Tue Feb 22, 2011 2:37 pm

good design sir,what is the fuel used to drive the car..

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Jam Jar Car Fun

Post by PyroJoe » Tue Feb 22, 2011 3:28 pm

Thanks,
The fuel used is methanol. Ethanol works also if it is high proof alcohol. The total weight of the car and combustor are minimal. :wink:

ganuganu
Posts: 340
Joined: Tue Dec 14, 2010 7:31 am
Antipspambot question: 125
Location: india
Contact:

Re: Jam Jar Car Fun

Post by ganuganu » Thu Feb 24, 2011 2:59 pm

i wanna make a carjar like yours..can i use an axe deospray can as pulsejet and methanol as fuel.. :)

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Jam Jar Car Fun

Post by PyroJoe » Thu Feb 24, 2011 5:26 pm

This one is easier to build:
http://www.youtube.com/watch?v=9adWpZJi ... ture=feedf

If it can be done safely, I don't see why not.

ganuganu
Posts: 340
Joined: Tue Dec 14, 2010 7:31 am
Antipspambot question: 125
Location: india
Contact:

Re: Jam Jar Car Fun

Post by ganuganu » Fri Feb 25, 2011 3:58 am

can you say me what is the hole size in the can....

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Jam Jar Car Fun

Post by PyroJoe » Fri Feb 25, 2011 2:25 pm

For methanol fuel, approximate hole size is typically the diameter of the can multiplied by 0.151

a 75mm diameter can would need:

75mm x 0.151=11.325mm size hole

Mark
Posts: 10692
Joined: Sat Oct 11, 2003 10:14 pm

Re: Jam Jar Car Fun

Post by Mark » Sat Feb 26, 2011 5:16 am

Sometimes the temperature and the humidity will affect your jam jar. In summer in a humid climate, a smaller hole size will do fine but in cool weather it may be too restrictive and cause sudden flameouts. One time I had a very hard time trying to get a jar to run in the summer, they become so sluggish. As the temperature goes up, so does the vapor pressure of methanol. Cooler air is more dense. I would like to see some experiments at higher elevations just to see what the results are.
http://www.engineeringtoolbox.com/air-a ... d_462.html
Presentation is Everything

Ghrey
Posts: 286
Joined: Fri Feb 15, 2008 8:41 am
Antipspambot question: 125
Location: Studio City, California
Contact:

Re: Jam Jar Car Fun

Post by Ghrey » Fri Apr 04, 2014 1:28 pm

That looks like great fun. I've got to try it.

I do have an ATV in the works, ( Aquatic Test Vehicle ), I'll be back.....

When I have fuel and time again.

Cheers.
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Jam Jar Car Fun

Post by PyroJoe » Thu Jul 13, 2017 9:24 pm


Ghrey
Posts: 286
Joined: Fri Feb 15, 2008 8:41 am
Antipspambot question: 125
Location: Studio City, California
Contact:

Re: Jam Jar Car Fun

Post by Ghrey » Fri Jul 14, 2017 3:24 am

Always a crowd pleaser.
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

Post Reply