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Hello Karl
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Discussion Forum
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Jul 8 2008, 12:57 PM EDT by
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Thread started: Jul 4 2008, 8:00 PM EDT
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Hi Karl, I am one of your Metca 2007 students and I would like to know how to fill my profile. Do I need to sign in? Thanks
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RE: Hello Karl
By: ,
Jul 8 2008, 12:57 PM EDT
Yes you need to register and then sign in.
Regards, Karl
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Dart's expansion chamber
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4. Concepts and Comparisons
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Jun 28 2008, 6:32 AM EDT by
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Thread started: Jun 28 2008, 6:32 AM EDT
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The Wankel engine is an Otto cycle engine. The expansion volume is equal to the compression volume. The D.A.R.T. engine uses a form of the Atkinson cycle, where the Expansion volume is greater than the compression volume. The Wankel's combustion chamber extends across the rotor face thus the expanding gases will not drive the rotor in only one direction if it was not for the inertia of the rotating masses. A Diesel engine can certainly achieve 50% efficiency. The size of the engine also contributes to the efficiency percentage. The volume of an engine increases by the cube of it dimensions, whereas the surface area only increases by the square of it dimensions. Large normally equates to increased efficiencies, the Airbus 380 would be a good example of its capacity to drag ratio. The same is true with engines when comparing volumetric efficiencies. Therefore the relative size of the engines must also be taken into consideration. I hope this clarifies the claims (White-Smoke)
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Anonymous |
DART's expansion chamber
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4. Concepts and Comparisons
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Jun 20 2008, 1:23 AM EDT by
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Thread started: Jun 20 2008, 1:23 AM EDT
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Above, you state that the Wankel gets low efficiency due in part to, "a long and narrow combustion chamber". However, the Wankel has a significantly smaller area to volume ratio than any DART diagram or animation (including the ones on Wikipedia).
I can certainly see and agree with Wankel's lower compression ratios causing greater inefficiency. (BTW, I should point out that on average, the Wankel's compression ratio compares favorably with other gasoline engines out there; remember, the higher the ratio, the more octane, and hence expense!, the gasoline needed!).
However, I call into question your singling out the Wankel's area-to-volume ratio.
Also, a diesel engine does not get 50% efficiency. Carnot's limit is 50% -- to claim higher efficiencies for a thermodynamic system would be equivalent to an over-unity device. A diesel gets 30% to 35% efficiency, while gasoline engines get only 15% to 25%. Some Stirling-cycle devices have achieved 45%, but they're engineered by NASA, so it's not likely we'll be seeing these any time soon.
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Anonymous |
Steering Effects
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Angulo, Juan Jacobo
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May 24 2008, 2:44 AM EDT by
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Thread started: May 21 2008, 4:07 PM EDT
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Hello Karl, how are you. This is Jacobo Angulo writing (METCA 2007). How is the METCA this year? Hope you are still having a good time there.
I have a question regarding steering effects on the tire load variation. I'm programming a little simulator for my final project and I need to model these effects. I couldn't find the link to change my profile and post my question there, so I'm doing it here as a thread.
How do you calculate or model this change in load due to steering (with caster)? I know exactly how much each wheel moves up or down, but I can't find an easy way to calculate the change in load. I was starting to program a full multi-body dynamics simulation, but it would take me very long. I was wondering if you have an idea for an easier way to model this.
Thanks a lot in advance,
Jacobo
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RE: Steering Effects
By: ,
May 24 2008, 2:44 AM EDT
Hi,
Nice to hear from you. What are you doing at the moment? Do you have my lecture notes still? If you do then my way of calculating weight transfer will allow you to add the steering effects. As you have stated, when you steer one front wheel moves up and the other down. This changes the angle of the virtual front axle. This in turn will change the dynamic corner weights front and rear. From my calculations you will see that the front and rear of the car are not connected in the first stage of the process. We have separate virtual axle angles front and rear, so the additional front axle angle due to steering can be added at this stage. When the front and rear are joined together in the last stage of the calculations the steering weight transfer is automatically taken into account. We can compare this with the weight transfers with no steering to see what additional weight transfer has occurred due to steering the front wheels. I hope this helps.
Regards, Karl
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Anonymous |
aaa
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Angulo, Juan Jacobo
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May 21 2008, 3:54 PM EDT by
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Thread started: May 21 2008, 3:54 PM EDT
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aaa
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white-smoke |
Quick comments and questions to White-Smoke
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Contact Information
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May 2 2008, 5:30 AM EDT by
white-smoke |
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Thread started: May 2 2008, 5:30 AM EDT
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If you have a quick comment or question on a particular page then please start a thread on that page. General questions can be posted here, or use the visitors page.
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Your Profile
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VIDAL MARTÍNEZ MATEO
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Apr 29 2008, 10:33 AM EDT by
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Thread started: Apr 29 2008, 10:33 AM EDT
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Please fill in this profile page and add a photograph of yourself. You can edit and add to this page however you like. If you have a question, then add a comment for me. The possibilities are endless and only limited by your imagination.
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Your Profile
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UNAI VILLAMERIEL REVILLA
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Apr 29 2008, 10:33 AM EDT by
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Thread started: Apr 29 2008, 10:33 AM EDT
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Please fill in this profile page and add a photograph of yourself. You can edit and add to this page however you like. If you have a question, then add a comment for me. The possibilities are endless and only limited by your imagination.
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Your Profile
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THOMAS RENAUD
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Apr 29 2008, 10:32 AM EDT by
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Thread started: Apr 29 2008, 10:32 AM EDT
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Please fill in this profile page and add a photograph of yourself. You can edit and add to this page however you like. If you have a question, then add a comment for me. The possibilities are endless and only limited by your imagination.
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SERGIO GARCÍA JIMÉNEZ
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Apr 29 2008, 10:32 AM EDT by
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Please fill in this profile page and add a photograph of yourself. You can edit and add to this page however you like. If you have a question, then add a comment for me. The possibilities are endless and only limited by your imagination.
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LUIS DIAZ
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Apr 29 2008, 10:31 AM EDT by
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Please fill in this profile page and add a photograph of yourself. You can edit and add to this page however you like. If you have a question, then add a comment for me. The possibilities are endless and only limited by your imagination.
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JORDI MASALÓ CODINA
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Apr 29 2008, 10:31 AM EDT by
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Please fill in this profile page and add a photograph of yourself. You can edit and add to this page however you like. If you have a question, then add a comment for me. The possibilities are endless and only limited by your imagination.
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JESSICA SOODEEN
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Apr 29 2008, 10:30 AM EDT by
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JAVIER OVANDO
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Apr 29 2008, 10:29 AM EDT by
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JAVIER DE JUAN GUTIERREZ
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Apr 29 2008, 10:29 AM EDT by
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IÑAKI PEY IBARBIA
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Apr 29 2008, 10:28 AM EDT by
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IELTXU MENDIZABAL
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Apr 29 2008, 10:28 AM EDT by
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FRANCISCO GARRIDO GUZMÁN
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Apr 29 2008, 10:28 AM EDT by
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ESTEVE JOSA FARRAN
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Apr 29 2008, 10:27 AM EDT by
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DARÍO ENDIKA IDIGORAS FERNANDEZ
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Apr 29 2008, 10:27 AM EDT by
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