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MythBuster TV Show (Jetcat P-60SE project)
12-13-2010, 08:31 AM
#51
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RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: roger.alli
Like others have stated, I think it will obey Newtons third law and travel in the opposite direction of the airmass flow.
Which direction it that is, will depend on how effective the “sail” is at directing the air mass. If the majority of the airmass flows back towards the turbine, the skate board will travel sail first. If the majority flows around the sail, it will travel turbine first. If there is an even split it will stay still.
I suspect it will travel sail first.
I would like to see the same experiment using a proper aerofoil section shape sail, with the air directed to flow over the sail.
Roger
Like others have stated, I think it will obey Newtons third law and travel in the opposite direction of the airmass flow.
Which direction it that is, will depend on how effective the “sail” is at directing the air mass. If the majority of the airmass flows back towards the turbine, the skate board will travel sail first. If the majority flows around the sail, it will travel turbine first. If there is an even split it will stay still.
I suspect it will travel sail first.
I would like to see the same experiment using a proper aerofoil section shape sail, with the air directed to flow over the sail.
Roger
Your answer it really good.
If the sail block off the all the thrust.
It will cancel both movement and stand still.
If the sail are more effecient.
Than it move forward.
If the sail less effecient.
It will move barkward.
It can move both direction depend on the power input.
If the sail got burn throught.
Than it move bardward.
But I already give a hint the sail hold together one of my post.
Becare not let the pictures fool you. I can easy edit flipping the pictures.
12-13-2010, 09:46 AM
#52
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RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: tamjets
Your answer it really good.
If the sail block off the all the thrust.
It will cancel both movement and stand still.
If the sail are more effecient.
Than it move forward.
If the sail less effecient.
It will move barkward.
It can move both direction depend on the power input.
If the sail got burn throught.
Than it move bardward.
But I already give a hint the sail hold together one of my post.
Becare not let the pictures fool you. I can easy edit flipping the pictures.
ORIGINAL: roger.alli
Like others have stated, I think it will obey Newtons third law and travel in the opposite direction of the airmass flow.
Which direction it that is, will depend on how effective the “sail” is at directing the air mass. If the majority of the airmass flows back towards the turbine, the skate board will travel sail first. If the majority flows around the sail, it will travel turbine first. If there is an even split it will stay still.
I suspect it will travel sail first.
I would like to see the same experiment using a proper aerofoil section shape sail, with the air directed to flow over the sail.
Roger
Like others have stated, I think it will obey Newtons third law and travel in the opposite direction of the airmass flow.
Which direction it that is, will depend on how effective the “sail” is at directing the air mass. If the majority of the airmass flows back towards the turbine, the skate board will travel sail first. If the majority flows around the sail, it will travel turbine first. If there is an even split it will stay still.
I suspect it will travel sail first.
I would like to see the same experiment using a proper aerofoil section shape sail, with the air directed to flow over the sail.
Roger
Your answer it really good.
If the sail block off the all the thrust.
It will cancel both movement and stand still.
If the sail are more effecient.
Than it move forward.
If the sail less effecient.
It will move barkward.
It can move both direction depend on the power input.
If the sail got burn throught.
Than it move bardward.
But I already give a hint the sail hold together one of my post.
Becare not let the pictures fool you. I can easy edit flipping the pictures.
12-13-2010, 09:51 AM
#53
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RE: MythBuster TV Show (Jetcat P-60SE project)
If the sail block off the all the thrust. It will cancel both movement and stand still.
.http://www.youtube.com/watch?v=MqUJb...eature=related
12-13-2010, 11:19 AM
#55
RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: basimpsn
Ok i'm making a small change. On startup to running mode, there should be a small reaction towards engine thrust (skate board free wheels). Then as the power increase the air deflect from the sail to the side just enough to reverse its direction. lets make it interesting $$$.
http://www.youtube.com/watch?v=MqUJb...eature=related
If the sail block off the all the thrust. It will cancel both movement and stand still.
.http://www.youtube.com/watch?v=MqUJb...eature=related
The sail appears to have the same effect as a clam-shell thrust reverser.
12-13-2010, 06:19 PM
#56
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RE: MythBuster TV Show (Jetcat P-60SE project)
where the sail captures 100% of thrust directed towards it,
However, check out this you tube video...... single engine jets taxing with drag chutes deployed,,,
[youtube]http://www.youtube.com/watch?v=RjOoFN7Ufz8[/youtube]
12-13-2010, 07:46 PM
#58
RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: Pete737
[I feel you, but even in an ideal scenario, where the sail captures 100% of thrust directed towards it, it cannot derive 100% of the net energy from the turbine or the system. In this example, the usful energy (thrust) will be converted mostly to thermal energy as the air heats and expands. Ideally, even if the sail absorbs 100% of the the thrust it will not be able to utilize the losses through air to air friction, The excitement of air molecules as well as the excitement of the sail material. The net tempature rise of the system is an energy loss that can only be removed from the ''sail side'' of the equation.
[I feel you, but even in an ideal scenario, where the sail captures 100% of thrust directed towards it, it cannot derive 100% of the net energy from the turbine or the system. In this example, the usful energy (thrust) will be converted mostly to thermal energy as the air heats and expands. Ideally, even if the sail absorbs 100% of the the thrust it will not be able to utilize the losses through air to air friction, The excitement of air molecules as well as the excitement of the sail material. The net tempature rise of the system is an energy loss that can only be removed from the ''sail side'' of the equation.
I think you might over complicate the issue a bit. Turbines are simple reaction engines. They work buy ejecting a mass in one direction, which pushes the engine in the opposite direction. Granted the mechanics used to eject the mass involves some complicated thermal dynamics and energy conversions within the turbine system. These conversions are not 100% efficient and lots of energy is lost due to friction etc, but the end result is an airmass being squirted out the back.
A reaction engine can eject hot air or cold, water, rocks or even pelicans, so long as the ejected material has mass, the push will be in the opposite direction.
In this case the engine is a system which includes both the turbine and the sail as they are connected. The direction of push will be opposite to the direction that the sail directs the airmass. The sail simply redirects the moving airmass, much like a clam shell reverser. Same principle really as a variable thrust nozzle used for steering and 3D maneuvers. (Which I think is silly on a jet)
Roger
12-13-2010, 08:36 PM
#59
RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: roger.alli
The direction of push will be opposite to the direction that the sail directs the airmass. The sail simply redirects the moving airmass, much like a clam shell reverser.
The direction of push will be opposite to the direction that the sail directs the airmass. The sail simply redirects the moving airmass, much like a clam shell reverser.
Typically after a show is filmed, it takes 2 to 3 months to air...Soooo, I'm more than half tempted to strap a jet/ airframe and all to a skateboard or the like (I haven't had/used a skateboard in well over 30 years
) with a sheet of Uncle Bob's heat blanket for a 'sail' and give it a go.I do believe the contraption will travel forward (the direction a jet normally travels).
... Or I could wait for the show to air. [&:]
12-13-2010, 08:39 PM
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RE: MythBuster TV Show (Jetcat P-60SE project)
It seems like it should be a fairly simple test for anyone with a jet turbine a sail and a skate board to do. I wish I had one to try it but I dont. Im now very interested in figuring out what the results will be.
12-14-2010, 06:38 AM
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RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: roger.alli
Hi Pete
I think you might over complicate the issue a bit. Turbines are simple reaction engines. They work buy ejecting a mass in one direction, which pushes the engine in the opposite direction. Granted the mechanics used to eject the mass involves some complicated thermal dynamics and energy conversions within the turbine system. These conversions are not 100% efficient and lots of energy is lost due to friction etc, but the end result is an airmass being squirted out the back.
A reaction engine can eject hot air or cold, water, rocks or even pelicans, so long as the ejected material has mass, the push will be in the opposite direction.
In this case the engine is a system which includes both the turbine and the sail as they are connected. The direction of push will be opposite to the direction that the sail directs the airmass. The sail simply redirects the moving airmass, much like a clam shell reverser. Same principle really as a variable thrust nozzle used for steering and 3D maneuvers. (Which I think is silly on a jet)
Roger
ORIGINAL: Pete737
[I feel you, but even in an ideal scenario, where the sail captures 100% of thrust directed towards it, it cannot derive 100% of the net energy from the turbine or the system. In this example, the usful energy (thrust) will be converted mostly to thermal energy as the air heats and expands. Ideally, even if the sail absorbs 100% of the the thrust it will not be able to utilize the losses through air to air friction, The excitement of air molecules as well as the excitement of the sail material. The net tempature rise of the system is an energy loss that can only be removed from the ''sail side'' of the equation.
[I feel you, but even in an ideal scenario, where the sail captures 100% of thrust directed towards it, it cannot derive 100% of the net energy from the turbine or the system. In this example, the usful energy (thrust) will be converted mostly to thermal energy as the air heats and expands. Ideally, even if the sail absorbs 100% of the the thrust it will not be able to utilize the losses through air to air friction, The excitement of air molecules as well as the excitement of the sail material. The net tempature rise of the system is an energy loss that can only be removed from the ''sail side'' of the equation.
I think you might over complicate the issue a bit. Turbines are simple reaction engines. They work buy ejecting a mass in one direction, which pushes the engine in the opposite direction. Granted the mechanics used to eject the mass involves some complicated thermal dynamics and energy conversions within the turbine system. These conversions are not 100% efficient and lots of energy is lost due to friction etc, but the end result is an airmass being squirted out the back.
A reaction engine can eject hot air or cold, water, rocks or even pelicans, so long as the ejected material has mass, the push will be in the opposite direction.
In this case the engine is a system which includes both the turbine and the sail as they are connected. The direction of push will be opposite to the direction that the sail directs the airmass. The sail simply redirects the moving airmass, much like a clam shell reverser. Same principle really as a variable thrust nozzle used for steering and 3D maneuvers. (Which I think is silly on a jet)
Roger
Yes sir they are simple reaction engines and as you mentioned there are losses due to friction, heating etc..
What Im saying is that in this particular case, The end result is measured in movement, The vehicle either moves forward or backward. The energy used to accolmplish this is thrust, The opposing force when the airmass is driven, As you said earlier.
You mentioned that the dynamics involved as gas is ejected from the turbine are not 100% effecient, from the turbines perspective, Of course. The effectiveness of the thrust is continually reduced as the gasses expand and move away from the turbine, using up kinetic energy, or thrust from one molecule to the next. Once the gas has exited the turbine, subsequent energy loss encountered (through the interactions you mentioned) only impact the sail. Obviously energy is always conserved but the usable energy in this experiment, thrust, is impacted on the sail side only.
12-14-2010, 06:55 AM
#63
RE: MythBuster TV Show (Jetcat P-60SE project)
I know the answer !!! I know the answer !!!!...... I set the same thing up in my driveway. The whole damn thing went up in flames after chasing me around the front yard, set the shrubs on fire, neighbors call the fire department and cops !!!! What a mess !!!!.... Like they say on all those other stupid idea TV shows, Don't try this at home !!!!!
Danno[8D]
Danno[8D]
05-09-2011, 12:50 PM
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RE: MythBuster TV Show (Jetcat P-60SE project)
I just saw the advertisment for the "blow your own sail" mythbusters episode. They say it will air this Wednesday at their usual time. I am now excited to see this episode.
David
David
05-09-2011, 03:46 PM
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RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: Woketman
There are many different Mythbusters episodes airing on Wednesday evening on Direct TV. I am assuming that the one that interests us is the one entitled ''Blow Your Own Sail'', correct???? Thanks guys......
There are many different Mythbusters episodes airing on Wednesday evening on Direct TV. I am assuming that the one that interests us is the one entitled ''Blow Your Own Sail'', correct???? Thanks guys......
05-11-2011, 05:36 PM
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RE: MythBuster TV Show (Jetcat P-60SE project)
ahh! Its true, at least the small scale so far. They really did blow their own sail with the model jet engine on the skateboard.
05-11-2011, 05:40 PM
#73
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RE: MythBuster TV Show (Jetcat P-60SE project)
ORIGINAL: basimpsn
Ok i'm making a small change. On startup to running mode, there should be a small reaction towards engine thrust (skate board free wheels). Then as the power increase the air deflect from the sail to the side just enough to reverse its direction. lets make it interesting $$$.
http://www.youtube.com/watch?v=MqUJb...eature=related
Ok i'm making a small change. On startup to running mode, there should be a small reaction towards engine thrust (skate board free wheels). Then as the power increase the air deflect from the sail to the side just enough to reverse its direction. lets make it interesting $$$
.http://www.youtube.com/watch?v=MqUJb...eature=related
