http://www.air-space.us/sci.aeronautics/22/1/ The science of aeronautics & related technology. (Moderated) en-us Mon, 15 Mar 2010 23:27:02 -0400 info@air-space.us http://www.air-space.us/ http://blogs.law.harvard.edu/tech/rss/ http://www.air-space.us/sci.aeronautics/22/Supersonic-diffuser-article358.htm http://www.air-space.us/sci.aeronautics/22/Supersonic-diffuser-article358.htm igt; I want to design a supersonic diffuser for a supersonic wind tunnel. i/i igt; would like to know some bibliography about diffusser efficiency,/i igt; entrance angle, second throat length . Can anyone help me. Thanks/i igt;/i Also look at Shapiros book on compressible fl .. Tue, 30 Jan 2007 21:18:00 -0500 http://www.air-space.us/sci.aeronautics/22/Supersonic-diffuser-article357.htm http://www.air-space.us/sci.aeronautics/22/Supersonic-diffuser-article357.htm igt; I want to design a supersonic diffuser for a supersonic wind tunnel. i/i igt; would like to know some bibliography about diffusser efficiency,/i igt; entrance angle, second throat length . Can anyone help me. Thanks/i igt;/i There is some discussion about supersonic wind .. Tue, 30 Jan 2007 21:16:40 -0500 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article356.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article356.htm igt; Think normal car differential with the power input at the wheel/i igt; shafts and power output at the quot;input shaftquot;./i igt; /i Considering the sync portion of the question: The problem here is to provide for load sharing without a tendency of the two engines to .. Tue, 30 Jan 2007 21:14:18 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article355.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article355.htm igt; gt; And someone tell us how to explain how circulation induces lift/i igt; gt; to a budding pilot./i igt;/i igt; Track the path of a single air particle as the airfoil approaches and/i igt; passes. It will move, roughly, in a circle (aka circulation). A particle/i .. Tue, 30 Jan 2007 21:13:12 -0500 http://www.air-space.us/sci.aeronautics/22/About-Spoilers-on-cars-article354.htm http://www.air-space.us/sci.aeronautics/22/About-Spoilers-on-cars-article354.htm igt; what do you think about the spoilers mounted on the rear window/i igt; Id like to install one on my Audi A3 (for the aesthetics effect) but/i igt; Im insecure about his effect on boundary layer./i igt; Do you think it can raise the drag/i Short answer: Yes. The questi .. Tue, 30 Jan 2007 21:12:03 -0500 http://www.air-space.us/sci.aeronautics/22/What-is-the-difference-between-total-and-stagnation-pressure-article353.htm http://www.air-space.us/sci.aeronautics/22/What-is-the-difference-between-total-and-stagnation-pressure-article353.htm igt; Im an aeronautical engineering student who is thoroughly confused/i igt; about the difference between total and stagnation pressures in a flow/i igt; (if any). When do we measure total pressure and when do we measure/i igt; stagnation pressure in a given flow Why do we nee .. Tue, 30 Jan 2007 21:11:14 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article352.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article352.htm igt; My feeling is that there is no full circulation because it stops at the/i igt; stagnation points where there is upwash at the leading edge and downwash at/i igt; the trailing edge BECAUSE of Bernoullis theory, however Bernoullis theory/i igt; alone does not explain lift .. Tue, 30 Jan 2007 21:10:14 -0500 http://www.air-space.us/sci.aeronautics/22/American-Society-of-Aeronautic-Engineers-article351.htm http://www.air-space.us/sci.aeronautics/22/American-Society-of-Aeronautic-Engineers-article351.htm I am researching professional societies in aeronautics. I am aware of the start of the IAS in 193032, I was also aware that the SAE has an aerospace division. In reading the history of the later, it turns out there was an American Society of Aeronautic Engineers that was merged in the SAE in 191 .. Tue, 30 Jan 2007 21:09:39 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article350.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article350.htm If you are able to get very close to the approach end of a runway serving heavy jets (727 and up) you can usually see the downwash effect on the smoke trail as the airplanes quot;cross the fencequot;. AMAF if you can get very close to the centerline of the runway you can usually feel the downwas .. Tue, 30 Jan 2007 21:08:51 -0500 http://www.air-space.us/sci.aeronautics/22/About-Spoilers-on-cars-article349.htm http://www.air-space.us/sci.aeronautics/22/About-Spoilers-on-cars-article349.htm igt; what do you think about the spoilers mounted on the rear window/i igt; Id like to install one on my Audi A3 (for the aesthetics effect) but/i igt; Im insecure about his effect on boundary layer./i igt; Do you think it can raise the drag/i Maybe, maybe not. The devil i .. Tue, 30 Jan 2007 21:08:11 -0500 http://www.air-space.us/sci.aeronautics/22/UAVs-article348.htm http://www.air-space.us/sci.aeronautics/22/UAVs-article348.htm igt; Can anyone recommend me any book on UAV design or guide to build/i igt; one from scratch or experience doing them starting from the sizing/i igt; equations to the final prototype Thanks/i igt; /i The laws of aerodynamics do not change depending on whether there is a pi .. Tue, 30 Jan 2007 21:07:29 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article347.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article347.htm igt; I choose not to teach the circulation theory to my students because I/i igt; dont think it exists in the manner the term suggests it does. I understand/i igt; what people are trying to explain by using the term quot;circulationquot; (basically/i igt; upwash and downwa .. Tue, 30 Jan 2007 21:06:54 -0500 http://www.air-space.us/sci.aeronautics/22/KuttaJoukowski-theorem-in-compressible-flow-article346.htm http://www.air-space.us/sci.aeronautics/22/KuttaJoukowski-theorem-in-compressible-flow-article346.htm Is Kutta Joukowski theorem still applicable in compressible (subsonic) flow In other words, does the same circulation produces the same lift at 0.2 and 0.8 mach (V being the same, of course) Marco Tue, 30 Jan 2007 21:06:06 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article345.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article345.htm igt; I choose not to teach the circulation theory to my students because I/i igt; dont think it exists in the manner the term suggests it does. I /i igt; understand/i igt; what people are trying to explain by using the term quot;circulationquot; /i igt; (basically/i .. Tue, 30 Jan 2007 21:05:23 -0500 http://www.air-space.us/sci.aeronautics/22/Jet-engine-noise-suppressor-article344.htm http://www.air-space.us/sci.aeronautics/22/Jet-engine-noise-suppressor-article344.htm igt; Can anyone tell me how a noise suppressor for a turbojet engine works/i Most of the noise from a turbojet comes from shearing between the highspeed hot exhaust jet and the stationary cool ambient air. Most of the noise suppressors (aka hushkits) are designed to promote rapid mixing .. Tue, 30 Jan 2007 21:04:39 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article343.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article343.htm igt;Unfortunately, there IS no simple explanation of the effect of airfoil/i igt;camber without getting into advanced fluid mechanics and differential/i igt;equations. I liked the explanation of a former sci.aero moderator,/i igt;Mary Shafer action of the quot;lift daemonsquot .. Tue, 30 Jan 2007 21:04:00 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article342.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article342.htm igt;gt; And someone tell us how to explain how circulation induces lift/i igt;gt; to a budding pilot./i .... igt;A particle /i igt;going over the wing will initially move forward and up due to positive /i igt;pressure from the leading edge, then get pulled back and down /i .. Tue, 30 Jan 2007 21:03:17 -0500 http://www.air-space.us/sci.aeronautics/22/Circulation-control-technique-article341.htm http://www.air-space.us/sci.aeronautics/22/Circulation-control-technique-article341.htm I have just done my Msc thesis on circulation control of a marine propeller duct. It also proposes a new type of non ducted propeller that can utilise the effect. It may be of interest to some people now or in the future so just in case anyone is interested you can find it here: http://www.geoci .. Mon, 11 Dec 2006 13:27:11 -0500 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article340.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article340.htm Think normal car differential with the power input at the wheel shafts and power output at the quot;input shaftquot;. Mon, 11 Dec 2006 13:26:02 -0500 http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article339.htm http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article339.htm I use a commercial flight simulator that is also available for home use. It is call Xplane and is developed by Austin Meyer. It comes with quot;planemakerquot; software, and if you know the drag coefficient of the components, you can put them in easily. Adam Mon, 11 Dec 2006 13:24:21 -0500 http://www.air-space.us/sci.aeronautics/22/About-Spoilers-on-cars-article338.htm http://www.air-space.us/sci.aeronautics/22/About-Spoilers-on-cars-article338.htm Hi, what do you think about the spoilers mounted on the rear window Id like to install one on my Audi A3 (for the aesthetics effect) but Im insecure about his effect on boundary layer. Do you think it can raise the drag Thanks. Francesco. Italy. Mon, 11 Dec 2006 13:23:18 -0500 http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article337.htm http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article337.htm igt; Can anyone suggest aerodynamics simulation software that will allow me/i igt; to simulate the entire aircraft (and not just airfoil) including/i igt; fuselage, wings, tail, canards, etc. In essence, I want to design a/i igt; 3D aircraft using this tool and then simulate it .. Mon, 11 Dec 2006 13:21:34 -0500 http://www.air-space.us/sci.aeronautics/22/Jet-engine-noise-suppressor-article336.htm http://www.air-space.us/sci.aeronautics/22/Jet-engine-noise-suppressor-article336.htm Can anyone tell me how a noise suppressor for a turbojet engine works Mon, 11 Dec 2006 13:20:11 -0500 http://www.air-space.us/sci.aeronautics/22/UAVs-article335.htm http://www.air-space.us/sci.aeronautics/22/UAVs-article335.htm Can anyone recommend me any book on UAV design or guide to build one from scratch or experience doing them starting from the sizing equations to the final prototype Thanks Mon, 11 Dec 2006 13:19:35 -0500 http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article334.htm http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article334.htm igt; Can anyone suggest aerodynamics simulation software that will allow me/i igt; to simulate the entire aircraft (and not just airfoil) including/i igt; fuselage, wings, tail, canards, etc. In essence, I want to design a/i igt; 3D aircraft using this tool and then simulate it .. Mon, 11 Dec 2006 13:18:17 -0500 http://www.air-space.us/sci.aeronautics/22/Supersonic-diffuser-article333.htm http://www.air-space.us/sci.aeronautics/22/Supersonic-diffuser-article333.htm I want to design a supersonic diffuser for a supersonic wind tunnel. i would like to know some bibliography about diffusser efficiency, entrance angle, second throat length . Can anyone help me. Thanks Mon, 11 Dec 2006 13:17:00 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article332.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article332.htm igt; Someone tell us how to explain how circulation induces lift/i igt; to a budding pilot. Bernoulli is easier to understand and demonstrate./i igt; Oh, yeah, FWIW, a supercritical wing produces lift because its at an/i igt; angle of attack, just like a symmetrical or plane surf .. Mon, 11 Dec 2006 13:16:26 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article331.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article331.htm igt; Well. I cant add to the Bernoulli discussion because its over 30 days/i igt; old or has been closed by the moderator. (Remove it from the list,/i igt; then). And someone tell us how to explain how circulation induces lift/i igt; to a budding pilot. Bernoulli is easier to un .. Mon, 11 Dec 2006 13:15:16 -0500 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article330.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article330.htm igt; Flowwise Circulation is a pure mathematical model, for correcting the/i igt; Potential flow field/i igt;/i igt; Its very easy to see that in real flight there is no flowwise/i igt; circulation around the wing, only the spanwise circulation in/i igt; connection wit .. Mon, 11 Dec 2006 13:14:35 -0500 http://www.air-space.us/sci.aeronautics/22/A340-article329.htm http://www.air-space.us/sci.aeronautics/22/A340-article329.htm igt; Do you have any recommended website or text book about A340,/i igt; particularly about its wing structure. i am a student who is doing/i igt; about wing structure of A340. Thank you for your helps....../i What do you need to know about it Airbus uses pretty much the same str .. Mon, 11 Dec 2006 13:13:39 -0500 http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article328.htm http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article328.htm igt; Can anyone suggest aerodynamics simulation software that will allow me/i igt; to simulate the entire aircraft (and not just airfoil) including/i igt; fuselage, wings, tail, canards, etc. In essence, I want to design a/i igt; 3D aircraft using this tool and then simulate it .. Mon, 11 Dec 2006 13:06:25 -0500 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article327.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article327.htm igt; And someone tell us how to explain how circulation induces lift/i igt; to a budding pilot./i Track the path of a single air particle as the airfoil approaches and passes. It will move, roughly, in a circle (aka circulation). A particle going over the wing will initially move for .. Mon, 11 Dec 2006 13:05:49 -0500 http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article326.htm http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article326.htm igt; Can anyone suggest aerodynamics simulation software that will allow me/i igt; to simulate the entire aircraft (and not just airfoil) including/i igt; fuselage, wings, tail, canards, etc. In essence, I want to design a/i igt; 3D aircraft using this tool and then simulate it .. Mon, 11 Dec 2006 13:05:08 -0500 http://www.air-space.us/sci.aeronautics/22/Saabs-early-regional-jet-design-of-60s--70s-article322.htm http://www.air-space.us/sci.aeronautics/22/Saabs-early-regional-jet-design-of-60s--70s-article322.htm A couple of months ago I saw a web page giving information about an early regional jet project of Saab aircraft. Even there was a drawing of the projected aircraft. For the last two days, Ive been searching for the same site and other web sites regarding Saabs early regional jet design, but I am .. Tue, 10 Oct 2006 17:53:19 -0400 http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article321.htm http://www.air-space.us/sci.aeronautics/22/The-Wronger-Bernoulli-etc-article321.htm Well. I cant add to the Bernoulli discussion because its over 30 days old or has been closed by the moderator. (Remove it from the list, then). And someone tell us how to explain how circulation induces lift to a budding pilot. Bernoulli is easier to understand and demonstrate. Oh, yeah, FWIW, a .. Tue, 10 Oct 2006 17:52:42 -0400 http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article320.htm http://www.air-space.us/sci.aeronautics/22/Aircraft-simulation-software-article320.htm Can anyone suggest aerodynamics simulation software that will allow me to simulate the entire aircraft (and not just airfoil) including fuselage, wings, tail, canards, etc. In essence, I want to design a 3D aircraft using this tool and then simulate its flight dynamics to see if it is airworthy .. Tue, 10 Oct 2006 17:51:07 -0400 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article319.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article319.htm igt; is there any information about combining gearboxes. If two engines/i igt; power say one rotor how can this be acomplished without total/i igt; synchronization of the engines/i igt;/i igt; Thanks a lot/i igt; Achilleas/i I seem to recall our X18 VTOL at Edw .. Tue, 10 Oct 2006 17:50:26 -0400 http://www.air-space.us/sci.aeronautics/22/A340-article318.htm http://www.air-space.us/sci.aeronautics/22/A340-article318.htm Do you have any recommended website or text book about A340, particularly about its wing structure. i am a student who is doing about wing structure of A340. Thank you for your helps...... Tue, 10 Oct 2006 17:11:58 -0400 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article317.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article317.htm igt; gt; is there any information about combining gearboxes. If two engines/i igt; gt; power say one rotor how can this be acomplished without total/i igt; gt; synchronization of the engines/i igt; /i igt; The strength of the shafts automatically quot;synchronizesquot; .. Tue, 10 Oct 2006 17:11:29 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article316.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article316.htm igt; gt; All new airliners of Airbus or Boeing make and all top bizjets, have/i igt; gt; low drag quot;supercritical wingsquot;, with almost flat upper surface and/i igt; gt; curved lower surface (to host wing beam and fuel)/i igt; gt;/i igt; gt; I have never seen Sci .. Tue, 10 Oct 2006 17:10:48 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article315.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article315.htm igt; gt; All new airliners of Airbus or Boeing make and all top bizjets, have/i igt; gt; low drag quot;supercritical wingsquot;, with almost flat upper surface and/i igt; gt; curved lower surface (to host wing beam and fuel)/i igt; gt;/i igt; gt; I have never seen Sci .. Tue, 10 Oct 2006 17:09:58 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article314.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article314.htm igt; Bernoulli equation seems to very misunderstod by americans, even/i igt; respected universities and Professors should know better about the/i igt; physics/i Everybody seems to want to be an aerodynamicist, and explain Bernoullis Theorem. See todays quot;Overboardquot; .. Wed, 23 Aug 2006 14:16:38 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article313.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article313.htm igt; gt; gt; A recent issue of Scientific American carries a mind virus :)/i igt; gt; gt;/i igt; gt; gt; In the quot;Working Knowledgequot; column, the author presents an incorrect and/i igt; gt; gt; longdebunked explanation of how wings work:/i igt; gt; gt;/i .. Wed, 23 Aug 2006 14:15:22 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article312.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article312.htm igt; All new airliners of Airbus or Boeing make and all top bizjets, have/i igt; low drag quot;supercritical wingsquot;, with almost flat upper surface and/i igt; curved lower surface (to host wing beam and fuel)/i igt;/i igt; I have never seen Scientific American explain .. Wed, 23 Aug 2006 14:05:27 -0400 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article311.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article311.htm igt;is there any information about combining gearboxes. If two engines/i igt;power say one rotor how can this be acomplished without total/i igt;synchronization of the engines/i A limited slip diff with a freerwheel, one idly supposes Brian Whatcott Altus OK Wed, 23 Aug 2006 14:04:39 -0400 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article310.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article310.htm igt; is there any information about combining gearboxes. If two engines/i igt; power say one rotor how can this be acomplished without total/i igt; synchronization of the engines/i The strength of the shafts automatically quot;synchronizesquot; the engines. The engines cannot tur .. Wed, 23 Aug 2006 14:03:55 -0400 http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article309.htm http://www.air-space.us/sci.aeronautics/22/Combining-gearbox-article309.htm Hello there, is there any information about combining gearboxes. If two engines power say one rotor how can this be acomplished without total synchronization of the engines Thanks a lot Achilleas Tue, 08 Aug 2006 11:53:15 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article308.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article308.htm igt; gt; A recent issue of Scientific American carries a mind virus :)/i igt; gt;/i igt; gt; In the quot;Working Knowledgequot; column, the author presents an incorrect and/i igt; gt; longdebunked explanation of how wings work:/i igt; gt;/i igt; gt; quot;becau .. Tue, 08 Aug 2006 11:52:40 -0400 http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article307.htm http://www.air-space.us/sci.aeronautics/22/The-wrong-quotBernoulliquot-explanation-in-Sci-American-for-April-2005-article307.htm Some interesting info for interested readers: http://user.unifrankfurt.de/weltner/Flight/PHYSIC4.htm http://user.unifrankfurt.de/weltner/Mis6/mis6.html http://amasci.com/wing/airfoil.html http://www.aa.washington.edu/faculty/eberhardt/lift.htm Tue, 08 Aug 2006 11:51:52 -0400 http://www.air-space.us/sci.aeronautics/22/X29-article306.htm http://www.air-space.us/sci.aeronautics/22/X29-article306.htm igt; Does anyone know if it was Lear or Honeywell who built the flight/i igt; control computers for the X29 /i Pretty sure it was Honeywell. I was working at Honeywell at the time and the company made a big thing about it. Tue, 08 Aug 2006 11:51:20 -0400