[amsat-bb] Re: Path to HEO
Hi James et all Thanks for the very nice comments. Here are some additional thoughts 1. The Van Allen belt radiation might be our toughest challenge so let think about an orbit 16000 KM 2. IF we were to put 3 sat up this would give us nice coverage and longer operating time 3. There are flight heritage reaction wheels that consume 2 watts 4. We a little luck we can start from 600 KM orbit 5. If we are really clever we might have a sat to sat relay to extend time and range coverage. nick -Original Message- From: James Duffey [mailto:jamesduf...@comcast.net] Sent: Sunday, April 28, 2013 10:35 PM To: Franklin Antonio Cc: James Duffey; Nick Pugh; Amsat-bb@amsat.org Subject: Re: [amsat-bb] Re: Path to HEO Well I did a rough back of the envelope calculation for the time required to accumulate the energy necessary to get from LEO to HEO, but there are a lot of details that still need to be calculated. And the devil is in the details. But this will get things started The difference in orbital energy between a LEO and GEO is about 25 MJ/kg. So, for a 10 kg nano sat, we would need to supply at least 250 MJ. Now I suspect that when all is said and done, it cannot be done for that, but I haven't done any detailed orbital transfer calculations. OK, suppose we have Nick's 50 Watt solar panel, and lets also say that initially half of that power can be put into propulsion, the other half being needed for navigation, housekeeping, comm, and telemetry. You could probably get away with more for propulsion. So say we need to generate at least 250,000,000 (it is probably more) Joules of energy to get from LEO to HEO. The solar panel can supply 25 Watts or 25 Joules per second. so it will take 10,000,000 seconds to generate the 250MJ required. Now the satellite is only illuminated for roughly half an orbit, so we need to double the time to 20,000,000 seconds on orbit. Now there 31,536,000 seconds in a year, so it would take 231 days to accumulate the minimum amount of energy to get to GEO. Well, I neglected inefficiencies in the system, such as the ability of the ion-thruster to convert electricity into thrust and how efficiently the batteries or capacitors can be charged and store energy. I also ignored the drag at lower latitudes, which may be considerable. I suppose that one could only operate the thrusters while the spacecraft is illuminated and that would eliminate the storage problem. Say the whole system is 50% efficient, and I am guessing here, that would make it 462 days, or 15 months. I suppose that whether or not that is a long time, depends on your point of view. I'll bet if the transfer burn strategy is calculated it gets even worse. Things seldom get better. You can't do a simple Hohmann transfer, but would need to do multiple burns, or a continuous burn over the illuminated part of the orbit. I suppose that would produce an orbit that is not really circular at any given time but it might all average out over all the burns. A constant burn may be more efficient in terms of energy use that a Hohmann; I don't remember. I do remember that one wants to burn at apogee to get the biggest bang for the buck, and I suspect that the illuminated portion of the orbit is not always at apogee, so the energy will not be used efficiently. Now a GEO orbit, while a desirable goal, is not necessarily what is needed for amateur radio communication. Something short of GEO, and even elliptical would still be useful and only require repointing of the antenna from day to day, and perhaps hour to hour at Apogee. Orbits significantly higher than LEO, but lower than GEO are also very useful. Compare for example the available time per pass between ISS and AO-7, and for that matter the RS10, 11, 12 and 13 birds. One would need to plan how to go through the Van Allen belts, as with such a slow burn one would spend a lot of time where the radiation is high. All of this is not meant to be a rigorous calculation, but rather just an indication of whether it is reasonable, and if it is worth pursuing further. It does to seem to be within the realm of possibly, and probably should be pursued further, at least until a real show stopper shows up. - Duffey KK6MC -- KK6MC James Duffey Cedar Crest NM On Apr 28, 2013, at 3:34 PM, Franklin Antonio anto...@qti.qualcomm.com wrote: At 11:14 AM 4/28/2013, Nick Pugh wrote: I have just returned from a satellite conference and I think new technology will now give us a path to HEO. I've thought for a long time that ion engines (small thrust pushing for a long time, powered by electricity) could be of great value to us. Has anyone done the calculation to see how long it would take to go from LEO to HEO with an achievable ion engine? This seems like the first thing to calculate. If it takes less than 1 year, it seems worth serious investigation. There are many other hurdles, of course, such as attitude control (keeping
[amsat-bb] Re: Path to HEO
--- On Mon, 29/4/13, Stefan Wagener wagen...@gmail.com wrote: maybe I didn't make myself clear: LEO (low earth orbit) from 400 to 2000km or something like that HEO (high earth orbit) 2km Going from 310 to 700km in a year is not doing us anything. Romit-1 and the other CubeSats testing ion engines will definitely give us something - proof that it works in practice or an opportunity to learn from any problems / design issues that arise. Given that Space is a demanding environment I'm sure not all the ion motor CubeSats currently being developed will work as planned when deployed, it'll be a learning experience. Going from a 310 to a 700 km orbit in a year using the limited solar power generated from a standard 2U CubeSat will be a major step forward. It follows that to get up to 7200 km or even better 2 km will take years but could be speeded up by having CubeSats with large fold-out solar panels and more powerful motor. I say CubeSats rather than Microsats because of cost, a 35 kg microsat could cost $1 million just to get into LEO. I hope the various groups that have developed ion motor CubeSats are eventually successful is getting launches to LEO to test them out. 73 Trevor M5AKA ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: G5500 Rotor motor Question
Oh, I didn't measure the rotation speed of the motor during my rebuild, unfortunately. In all the research I did prior to the rebuild (=scrambling to find an equivalent motor) I didn't see any published specs on the unit either. I'd think Domenico's calculations would probably be the closest, since it is a simple 2-pole AC motor. 73! Dave KB5WIA On Sun, Apr 28, 2013 at 2:31 PM, Gregory Beat gregory.b...@comcast.netwrote: You could ask Dave Palmer, KB5WIA if he noted that spec., when he rebuilt his Yaesu motor last year (March 2012) http://kb5wia.blogspot.com/2012/03/yaesu-g5500-rotator-motor-repair.html w9gb == From: Mike Hoblinski To: amsat-bb@amsat.org Subject: [amsat-bb] G5500 Rotor motor Question Anybody know what the rpm of the AC motors are. I know from the Yaesu specs that after all of the gear reduction they list EL as 67 seconds for EL and 58 Seconds for AZ. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Observations From ESA's Herschel Observatory End
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=51550 73s Bernhard VA6BMJ @ DO33FL ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Successful Powered Flight For SpaceShipTwo
http://www.newspacejournal.com/2013/04/29/spaceshiptwos-first-powered-flight-a-success/ http://spacecoalition.com/blog/spaceshiptwo-en-route-for-projected-first-powered-flight 73s Bernhard VA6BMJ @ DO33FL ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] What birds
Thanks to everyone that answered. Hope to work you on one of them one of these days. Thanks again Nels W0TUP North Dakota ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
Thanks Bob, That's why it is important to read the complete conversation. This is NOT about Cubesats, staying in orbit, etc. It is about getting into an HEO beyond 2km. On Mon, Apr 29, 2013 at 1:34 PM, Robert Bruninga bruni...@usna.edu wrote: Going from 310 to 700km in a year is not doing us anything. Im not following this closely, but that statement misses the most important reason for doing this... *to*stay*in*orbit! The lifetime of a cubesat at 310km is only a few weeks at most. The life time at 700km is tens of years. The minimum requirement then for an ION thruster, then, is to be able to at least be slightly greater than the loss on every orbit. Then it is worth its weight in gold! Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] More On SpaceShipTwo's Flight
http://www.parabolicarc.com/2013/04/29/pictures-of-spaceshiptwos-first-powered-flight/ http://www.parabolicarc.com/2013/04/29/spaceshiptwo-completes-first-powered-flight/ http://www.virgingalactic.com/news/item/virgin-galactic-breaks-speed-of-sound-in-first-rocket-powered-flight-of-spaceshiptwo/ 73s Bernhard VA6BMJ @ DO33FL ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: G5500 Rotor motor Question
Has anyone measured the gear reduction used in the rotor to compute the raw speed of the motor. I have always been a fan of checking theoretical calculations with actual measurements to make sure we stay within the ballpark. Fortunately I have never had to take my G5500 apart so have never checked the gear ratio. W9KE Tom Doyle On Mon, Apr 29, 2013 at 11:29 AM, David Palmer KB5WIA kb5...@amsat.orgwrote: Oh, I didn't measure the rotation speed of the motor during my rebuild, unfortunately. In all the research I did prior to the rebuild (=scrambling to find an equivalent motor) I didn't see any published specs on the unit either. I'd think Domenico's calculations would probably be the closest, since it is a simple 2-pole AC motor. 73! Dave KB5WIA On Sun, Apr 28, 2013 at 2:31 PM, Gregory Beat gregory.b...@comcast.net wrote: You could ask Dave Palmer, KB5WIA if he noted that spec., when he rebuilt his Yaesu motor last year (March 2012) http://kb5wia.blogspot.com/2012/03/yaesu-g5500-rotator-motor-repair.html w9gb == From: Mike Hoblinski To: amsat-bb@amsat.org Subject: [amsat-bb] G5500 Rotor motor Question Anybody know what the rpm of the AC motors are. I know from the Yaesu specs that after all of the gear reduction they list EL as 67 seconds for EL and 58 Seconds for AZ. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb -- Sent from my computer. tom ... ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
Going from 310 to 700km in a year is not doing us anything. Im not following this closely, but that statement misses the most important reason for doing this... *to*stay*in*orbit! The lifetime of a cubesat at 310km is only a few weeks at most. The life time at 700km is tens of years. The minimum requirement then for an ION thruster, then, is to be able to at least be slightly greater than the loss on every orbit. Then it is worth its weight in gold! Bob, Wb4APR ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
--- On Mon, 29/4/13, Stefan Wagener wagen...@gmail.com wrote: Thanks Bob, That's why it is important to read the complete conversation. This is NOT about Cubesats, staying in orbit, etc. It is about getting into an HEO beyond 2km. It's the same thing, what gets you from 310 to 700 km can also get you to 7200 or 2 km. But first the technology needs to be proved in Space CubeSats like Romit-1 will do that if they can get launches. Bob, on the topic of extending orbit lifetime there's a UK company, a University of Southampton spin-off, who are doing some interesting work in this area. Mars-Space Ltd have developed a Pulse Plasma Thruster for a 1U CubeSat designed to extend orbit lifetime which was shown at a recent CubeSat Workshop, details at http://www.mars-space.co.uk/Pages/MicroPPTforCubesats.aspx They are also working on Ion Motors. 73 Trevor M5AKA ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] EL94
Looks like I'll be on Marathon in the Keys Weds night to Friday early morning. If you need EL94 on satellite let me know and we'll make a schedule. 73, Drew KO4MA ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
One thing that would seem to be a concern to me is how to keep the attitude steady while the ion engine is firing. Yes, not much thrust, but to make the most of it, you want it pointing in as close to the ideal direction as possible. I don't know how the various probes like Hayabusa and Dawn do it.. Cold gas? Gyro? I would not think a bar magnet would be good enough (certainly not for deep space probes, but even for earth orbit). Starting to get more complicated. Another thought about the really cool energy analysis done by KK6MC: Besides the duty cycle imposed by wanting to be out of eclipse, there is another duty cycle imposed by the starting orbit and the desired eccentricity. For example if you were starting from a highly elliptical GTO and you want to get to high circular, you need to thrust mainly at the apogee in order to raise the perigee. If you are circular and you want to be elliptical with perigee equal to the starting height, you thrust at what will be the perigee to raise the apogee. (Of course you probably want to raise both ends some, and you may want to change the plane too but that's the general idea.) Thanks for bringing this up...great thought experiments, and that's how real projects begin! Burns, W2BFJ ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Sat32PC
I need some advice. I have been trying to run Sat32PC to track satellites with my G5500 rotor and LVB Tracker. It seems I am running into one problem after another. Many times the program stops working when I get towards a lower elevation while tracking the satellite. I get most of the pass and then everything stops. I cannot park the rotor and must reboot the computer as restarting the program gives com errors. This afternoon Sat32PC was tracking a ghost. It clearly thought something was flying above. The only satellite I had selected was FO-29 and it definitely was well past a fly over. In fact, I could not find an amateur satellite that was anywhere that the program should be tracking. I would really like to get the bugs out as I plan to use my Panasonic Toughbook in a portable operation. I am using the XP Professional operating system with the USB communicating with the LVB Tracker. I also have a Macbook and MacDoppler has operated flawlessly. It does what it is suppose to do and does it well. Please no flame wars over Mac vs PC. I use both and basically am happy with both. On Sat32PC, the Keps are updated so I am not feeding the controller wrong info. On the screen, the satellite position is visibly correct. On the bottom of the screen the Azimuth / Elevation were wrong when it was tracking the ghost. I have two Toughbooks and both exhibit the same problem. Has anyone had the same or similar problems? 73, -james W5AOO ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
Even if the technique required 5 years to advance to HEO it would be a positive step since the amateur launch opportunities directly to HEO are measured in decades and the cost in 10's millions of dollars. This reminds me of a commercial payload that failed to make GEO. The folks at AGI (STK Satellite Toolkit) devised a path circling the moon which used the lunar gravity to accelerate and return the satellite to its intended GEO position without depleting much of its limited station keeping fuel. -- Joe Leikhim Leikhim and Associates Communications Consultants Oviedo, Florida jleik...@leikhim.com 407-982-0446 WWW.LEIKHIM.COM ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Dayton, Satellites, Fun !!!!!
I am gathering up my clothes for my trip to Dayton. I hope to see and meet as many satellite folks as possible! I have my name in the hat to work at the AMSAT booth. I worked last year and had the best time! I keep seeing many emails about what satellites are operating. It seems many think that none are working. Well I can tell you that I am having a blast working FO-29, SO-50 , VO-52, and grandpa AO-7. I do admit that AO-7 has a bit of a stutter step when too many get on or someone cranks their power up too much. Take a look at the link Bob, W7LRD, posted regarding active satellites: http://aar29.free.fr/sat/indexlogin.php Each contact is so exciting. OMG, I worked Brazil last night too! FO-29 sounded just like 20 meters last night! It is so nice to hear those making their first contact and so nice to renew old friendships. Hope to meet you or at least work you! 73, -james W5AOO ...still excited about amateur radio after being active for 50+ years! ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Relay Turksat3usat Posting
Any further updates ? Did not copy TurkSAT3USAT on 2 passes over US today 16:47 and 18:25 Did copy CubeBUG both passes, still just a carrier, no packet Dave W0DHB Original Message- From: amsat-bb-boun...@amsat.org [mailto:amsat-bb-boun...@amsat.org] On Behalf Of JoAnne Maenpaa Sent: Sunday, April 28, 2013 6:16 PM To: 'amsat-bb' Subject: [amsat-bb] Relay Turksat3usat Posting Some on amsat-bb are not on Facebook. The Turksat3usat Team posts most of their updates on Facebook. Here is a copy/paste from Turksat3usat Fan Club on Facebook today: Turksat3usat Fan Club Önemli: TURKSAT-3USAT uydumuz bu gece Türkiye üzerinden yüksek açıda geçecek. Radyo amatörlerinden ricamız tekrar duyuru yapılana kadar sadece beacon sinyalini izlemeleri ve olabildiğince yüksek kaliteli (ve sıkıştırma yapmadan) ses kaydı yapmalarıdır. Kayıtlarınızı doğrudan turksat3u...@tamsat.org.tr adresine gönderebilirsiniz. Sinyal kaydınız ne kadar düşük olursa olsun tüm kayıtlarınızı gönderiniz. Teşekkürler. - Important: TURKSAT-3USAT uydumuz from Turkey will be high angle tonight. Radio beacon signal until the announcement again please only amatörlerinden monitor, and high-quality as possible (and without any compression) audio recording make bids. Records directly to turksat3u...@tamsat.org.tr. No matter how low the signal records all records. Thanks. (Translated by Bing) - AMSAT-NA and AMSAT-DL also have Facebook groups. -- 73 de JoAnne K9JKM k9...@amsat.org Editor, AMSAT Journal ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
schrieb Stefan Wagener on 2013-04-29 01:29: LEO (low earth orbit) from 400 to 2000km or something like that HEO (high earth orbit) 2km Going from 310 to 700km in a year is not doing us anything. We need a highly elliptical orbit (Apogee ~6km, Perigee 900km) similar to AO-40 to allow for cross continental communication. Let's check with some maths (*): Energy at 300 km: - Total Energy = kinetic energy + potential energy E_kin + E_pot = (m*v^2)/2 + m*g*h For simplicity, we choose mass as 1 kg, h = 300km, v = 1st cosmic velocity =~ 7100m/s 1*7200² + 1*9.81*300x10^3 = 2.8148x10^7 [Joule] Potential Energy is some 10% of the total energy. As this is for one kg of mass, and m goes linear in the above equations, you can scale with the mass of your satellite. Energy at 36000 km: --- Speed from radius and time for one orbit (1 day=84600 sec) v = 2*r*pi/t = 2*36x10^6*3.14159265/84600 = 2673.7 m/s E_kin + E_pot = (m*v^2)/2 + m*g*h = 3.57x10^6 + 3.53^8 =~ 3.56×10^8 [Joule] Now kinetic energy is only about 1% of the total energy! A LEO has about 8% the energy of an GEO. The satellite needs 3.29x10^8 J/Kg Energy to get from LEO to GEO. Lets say it's 10kg and has 50 W of power for thrust. 3.3x10^8 * 10 = 3.3x10^9 J thrust 1 Joule is 1 Watt / 1 second, 1 Watt second = 1 Joule 1 Watt day = 84600 Joule = 8.46x10^4 Joule Our 50 Watt ion drive can increase the energy by 4.23x10^6 Joule a day. How much days will LEO to GEO take: We have some 10^8 divided by some 10^6, it's a matter of months, the calculation says 77.8. But we should be satisfied to get an order of magnitude after the rough assumtions and estimations made before. If I made a mistake above, maybe this is off by an factor of 10, then it's 2 year. Still fine! Of course you have to count in the gas you want to ionize, which reduces the weight over time (but I was really bad at differential equations and would not get that right), and maybe the weight and power estimations are not very realistic, and using steady thrust instead of short impulses decreases efficiency in orbit changes, and changing from polar to equatorial orbit takes extra energy, and maybe an elliptic orbit takes less energy, and maybe some inaccuracies more. But this does not matter: In the end, it seems that changing from LEO to GEO or HEO is possible in sensible time. Regards Patrick (*) Disclaimer: This is High School maths, please double check and correct my calculations -- Engineers motto: cheap, good, fast: choose any two Patrick Strasser patrick at wirklich priv at ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
On 04/29/2013 03:50 PM, Patrick Strasser wrote: Speed from radius and time for one orbit (1 day=84600 sec)... Uh, 86400 sec... But the difference isn't particularly significant. -- 73, de Gus 8P6SM Barbados, the easternmost isle. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Path to HEO
Thanks, I like simple math. A 3U Cubesat can have deployable solar cells which will give you between 45 and 70 watts of power. That should drive an ion engine. Will need an active attitude control system and should start at the right orbit. Getting +-3kg to GTO is a $100.000? Don't know what the satellite would cost but we are now in a $ range that could be funded. Thoughts? Stefan On Mon, Apr 29, 2013 at 2:50 PM, Patrick Strasser patr...@wirklich.priv.atwrote: schrieb Stefan Wagener on 2013-04-29 01:29: LEO (low earth orbit) from 400 to 2000km or something like that HEO (high earth orbit) 2km Going from 310 to 700km in a year is not doing us anything. We need a highly elliptical orbit (Apogee ~6km, Perigee 900km) similar to AO-40 to allow for cross continental communication. Let's check with some maths (*): Energy at 300 km: - Total Energy = kinetic energy + potential energy E_kin + E_pot = (m*v^2)/2 + m*g*h For simplicity, we choose mass as 1 kg, h = 300km, v = 1st cosmic velocity =~ 7100m/s 1*7200² + 1*9.81*300x10^3 = 2.8148x10^7 [Joule] Potential Energy is some 10% of the total energy. As this is for one kg of mass, and m goes linear in the above equations, you can scale with the mass of your satellite. Energy at 36000 km: --- Speed from radius and time for one orbit (1 day=84600 sec) v = 2*r*pi/t = 2*36x10^6*3.14159265/84600 = 2673.7 m/s E_kin + E_pot = (m*v^2)/2 + m*g*h = 3.57x10^6 + 3.53^8 =~ 3.56×10^8 [Joule] Now kinetic energy is only about 1% of the total energy! A LEO has about 8% the energy of an GEO. The satellite needs 3.29x10^8 J/Kg Energy to get from LEO to GEO. Lets say it's 10kg and has 50 W of power for thrust. 3.3x10^8 * 10 = 3.3x10^9 J thrust 1 Joule is 1 Watt / 1 second, 1 Watt second = 1 Joule 1 Watt day = 84600 Joule = 8.46x10^4 Joule Our 50 Watt ion drive can increase the energy by 4.23x10^6 Joule a day. How much days will LEO to GEO take: We have some 10^8 divided by some 10^6, it's a matter of months, the calculation says 77.8. But we should be satisfied to get an order of magnitude after the rough assumtions and estimations made before. If I made a mistake above, maybe this is off by an factor of 10, then it's 2 year. Still fine! Of course you have to count in the gas you want to ionize, which reduces the weight over time (but I was really bad at differential equations and would not get that right), and maybe the weight and power estimations are not very realistic, and using steady thrust instead of short impulses decreases efficiency in orbit changes, and changing from polar to equatorial orbit takes extra energy, and maybe an elliptic orbit takes less energy, and maybe some inaccuracies more. But this does not matter: In the end, it seems that changing from LEO to GEO or HEO is possible in sensible time. Regards Patrick (*) Disclaimer: This is High School maths, please double check and correct my calculations -- Engineers motto: cheap, good, fast: choose any two Patrick Strasser patrick at wirklich priv at ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
[amsat-bb] Re: Dayton
Hi Jim! I'm also starting to get my things together for the Dayton Fest. I think hands down AMSAT has the best demo there. You can see and hear guys actually work the birds, see the setup and ask questions. Hope to see you there! Mike/N8GBU. ___ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
