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  1. H

    Molecular mass of He+MON and He+MMH

    But why to take the average and why not the sum of all three?
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    Molecular mass of He+MON and He+MMH

    Dear all I have a case. I have two tanks, one is filled with Helium gas and monomethylhydrazine(MMH) and another tank with Helium gas and Dinitrogentetraoxide(MON). Both tanks are at 47degC so they are in gaseous form. I want to know what will be the Molecular Mass of the gas. The...
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    Area under the curve of a roll data of satellite

    No meaning of degree seconds that I think of
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    Area under the curve of a roll data of satellite

    Dear Members, I would like to ask if we plot the Roll data of a satellite in degrees vs. the time, and if we take the area under the curve of this roll will give something meaningful? Looking forward for your reply. Regards,
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    Reaction wheels

    What i want to know is that a satellite having a spinning momentum wheel on 1 axis with constant angular velocity doesn't cause rotation on the satellite itself? But if the wheel speed is increased or decreased it will cause satellite to rotate. Is it explainable with any equation?
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    Reaction wheels

    But for a geo satellite it has an angular velocity equal to earth's rotation,right? So the angular velocity is not zero but constant. This angular rotation is provided by the wheel?
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    Reaction wheels

    Dears, I would like to know a basic thing, why does the Satellite doesn't rotate with the spinning wheel momentum wheel inside it?
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    How to get longitude from Two Line Element (TLE)

    Dear All I want to know the formula to extract the longitude of the satellite from the TLE below. I hope someone can help. Thanks 1 24652U 96063A 97251.85429118 .00000144 00000-0 00000-0 0 568 2 24652 0.0850 104.0202 0008355 303.2059 279.6585 1.00288964 3492
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    Difference Between Plasma and Radiation

    Yes normally when we look at the two effects we talk about plasma and radiation. But another thing I don't understand is Van Allan Radiation Belt. The name says its a radiation belt but it is a constituent of plasma. And then there is another plasma sheet which trails at the dark side of the...
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    Difference Between Solar proton event and Coronal mass Ejection

    Hi All Whenever there is a solar activity two things are mentioned, SPE, CME and X-ray. Does anyone know the difference between SPE and CME? I couldn't find a descriptive or convincing answer on these two. What particles are associated with CME, is X-ray a part of CME? And what effects could...
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    Difference Between Plasma and Radiation

    Hi all In general sometimes we talk about plasma effects on satellites and radiation effects on satellites. Can someone tell the difference between the two? Thanks and Best Regards Hamza
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    Silicon solar cell degradation due to solar fluxes

    I am trying to find the Absorbed dose for Silicon cells on a geostationary satellite from a period of (1996 to 2005) The Equation I have is: D(rad) = 1.68e-8 *((1/ρ)*dE/dx) * Phi Where: D is absorbed dose and units are (100 ergs/g or 0.01 J/Kg) (1/ρ)*dE/dx = (MeV*cm^2)/g...
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    Full Motion Antenna motors designing problem

    Thanks for your reply. I am a satellite engineer basically but I do have some mechanical background. And this is my first time to work on motors. Initially I can keep a accuracy of about +/- 1 degrees. I just want to know how can i theoretically design a motor for the required movement of...
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    Full Motion Antenna motors designing problem

    Dear All I want to design a Full motion Antenna. But I want to start from the scratch. Suppose I have a 1m parabolic Antenna and I want to install two motors (Elevation and Azimuth) The motors should be DC. And I want to know how to calculate all the parameters required to move the...
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    Thermal Resistance at a single point

    wow..pretty interesting to know this.
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    Calculating the force at a single point of contact

    Thanks again vk6kro.. I had done similar calculations, but wanted to confirm if it was the right way. I thought some tensor matrix might get involved. Thanks and Regards
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    Thermal Resistance at a single point

    Thanks for the descriptive explanation :) will try out some different techniques for sure. by the way, what is your specialty field? Still my problem remains. That how can I calculate theoretically the resistance require to reach around a 150 degree C temperature with a 1.5 A current through...
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    Thermal Resistance at a single point

    Yea, I have found some local shops here in germany and I will order them soon. And that is my concern now that if I only hook it up to nichrome wire then it might get cut. So i'm planing to pass it through 2 hooks and wrap the nichrome wire around it. I can use a washer like thing, but I am...
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    Calculating the force at a single point of contact

    Hi all May be someone can help me with this problem. There is a isa-chrome60 wire (d=0.5 mm, tensile strength=600 N/mm^2) which is held at both ends using end connectors ( length of the wire = 20mm). And there is a nylon wire (d=0.5 mm) which is under tension (because of torsion spring)...
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    Thermal Resistance at a single point

    Actually fishing line is commonly used in cubesats for their antenna deployments. So low temperature is not a problem for it. The link was of great help, but i think its in US. And it takes a long time to ship to europe and the cost of shipment would be far more than the item's. I was...
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    Thermal Resistance at a single point

    I don't know if dipping in nitrogen would be of anyhelp in this case. I am interested in using a resistive wire instead of a resistor. So the re-defined constraints now are that a voltage of 4V and a maximum current of 1.5A can flow through it. So with that in hand the resistance should be 2.66...
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    Thermal Resistance at a single point

    Although using an actuator is the best solution but its expensive for space applications.
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    Thermal Resistance at a single point

    Hi Thanks for the bundles of ideas. But the thing is that system has to be kept simple somehow because it is only one time operation. Therefore i proposed that the fishing line is hooked up to a small resistive wire under stress and the the fishing line is melted *somehow* the solar panels...
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    Thermal Resistance at a single point

    Hi vk6kro Thanks for your reply. Well the reason I cannot use a scissor is that the fishing line would be in space (on a satellite) :) I actually want to use it to hold the solar panels for a small satellite (CubeSat) and for the antennas. So you suggest to use a Nichrome wire for this purpose?
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    Converting Thermal Conductivity to Thermal Conduction/Resistance

    Thanks all... very much appreciated. I have a further query now which I have posted separately. hxxp://www.physicsforums.com/showthread.php?t=330491
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    Thermal Resistance at a single point

    Hi All I am having a design problem. I want to melt a fishing line which is in contact at a single point with some material. The problem is that I have a 5 V of supply and Power should be between 1-3W. Some other constraints are that the material to which the fishing line is connected should be...
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    Converting Thermal Conductivity to Thermal Conduction/Resistance

    Hi all I want to convert thermal conductivity to thermal conductance. The problem is with the units. for thermal conductivity the units are [W/(m.K)] and for thermal conductance the units are [W/K] For E.g for copper thermal conductivity is 400[W/m.K] how can I convert it to thermal...
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    Design Problems- Solar Panel design

    Dear Nvn and Gary350 Thanks a lot to both of you for your great replies. I will try working out what nvn suggested and then I will further ask. Gary 350 I have one more query regarding torsion springs. When the torsion springs are compressed their internal diameter would also...
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    Design Problems- Solar Panel design

    Thank you Danger. I do have the same views but the only thing that is bothering me is that as you might have seen from the figure that the lever-top part to which the panel is attached is only 2 mm thick. I want to know if that could hold the weight and open the panel. I have set the applied...
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    Design Problems- Solar Panel design

    Hi All I am designing the solar panel deployment mechanism using torsion springs for a satellite. I have a few questions to ask here and appreciate if someone could help: 1. How can I calculate the Force required by torsion spring to open the panel? ( mass of panel= 92.35 grams and...
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