Orbiter-Forum [Challenge] Varuna intercept
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 09-21-2016, 10:10 PM #16 JonnyBGoode Sky Marshal I'm getting back up to speed on my orbital mechanics first. :p I noticed... my Varuna is almost 90 degrees to the ecliptic? That can't be right. Varuna is supposed to be on the same inclination as Pluto. Last edited by JonnyBGoode; 09-21-2016 at 10:17 PM.
 09-22-2016, 05:18 AM #17 downloaderfan Orbinaut Quote: Originally Posted by JonnyBGoode  I noticed... my Varuna is almost 90 degrees to the ecliptic? That can't be right. Varuna is supposed to be on the same inclination as Pluto. Yes, when I started planning for this challenge in TransX, Quaoar & Varuna both looked almost 90 degrees inclined to the ecliptic, way more inclined than any other rock I had in orbiter. I looked at wikipedia for their ecliptic inclinations and found that they were around 8 & 17 degrees respectively. So I shrugged this off as some anomaly which I just didn't understand & continued with my planning. But, by the time I was done with my planning, it became very clear it was actually inclined to the ecliptic by somewhere around 90 degrees. Checked using the scenario editor, yup, it was 96 degrees. Even quaoar is inclined by 96 degrees with a different LAN. Both made by the same dev. The polar inclination of Varuna is what differentiates this challenge from a typical sling challenge and makes it somewhat more difficult. As I've already said, this challenge takes place in a parallel universe so you can think of Varuna actually being in a polar orbit around the sun in that universe. Weird meshes, weird inclinations. Yes, we have it all in this challenge brothers. Last edited by downloaderfan; 09-22-2016 at 05:38 AM.
 09-22-2016, 06:42 AM #18 JonnyBGoode Sky Marshal Oddly, the config file says "Inclination = 17.158", though it says the units are radians. Which might be the problem. 17 degrees would be about 0.3 radians. 17 radians is like 974 degrees.
 09-22-2016, 07:02 AM #19 downloaderfan Orbinaut Quote: Originally Posted by JonnyBGoode  Oddly, the config file says "Inclination = 17.158", though it says the units are radians. Which might be the problem. 17 degrees would be about 0.3 radians. 17 radians is like 974 degrees. True, changing the inclination & LAN to Code: ```Epoch = 2016.57905544148 ; SemiMajorAxis = 6442950279469.6591797 ; meters Eccentricity = 0.05052422717173251 Inclination = 0.2997823783734367975 ; rad LongAscNode = 1.6982957103063498483 ; rad LongPerihelion = 0.1165669506359328922 ; rad MeanLongitude = 1.9904093660688890743 ; rad``` in Varuna.cfg fixes the incorrect LAN & inclination of Varuna. But don't do that until you complete this challenge. Last edited by downloaderfan; 09-25-2016 at 07:24 AM. Reason: Added LongPerihelion & MeanLongitude
 09-22-2016, 07:15 AM #20 JonnyBGoode Sky Marshal So I'm thinking the best way to approach this challenge is to approach Jupiter from the poles; that would give you a 90 degree plane change pretty easily I should think?
 09-22-2016, 07:30 AM #21 downloaderfan Orbinaut Quote: Originally Posted by JonnyBGoode  So I'm thinking the best way to approach this challenge is to approach Jupiter from the poles; that would give you a 90 degree plane change pretty easily I should think? Try, I'm afraid I won't help you unless you've posted some detailed information here indicating that you've tried really hard.
 09-23-2016, 01:28 AM #22 JonnyBGoode Sky Marshal Quote: Originally Posted by downloaderfan  Checked using the scenario editor, yup, it was 96 degrees. Even quaoar is inclined by 96 degrees with a different LAN. Both made by the same dev. I'm wondering if Makemake is similarly inclined. Same dev... gonna go look... ---------- Post added at 06:28 PM ---------- Previous post was at 06:20 PM ---------- Answer: Yup!
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 09-23-2016, 08:01 PM #23 downloaderfan Orbinaut Ok, when I posted this challenge, I set the fuel amount & time limit based on some rough estimates. Today, I just flew this challenge and would like to share some information here. First of all, assuming you have the right plan, the fuel spent in MCCs will differ from person to person depending on what MFD they use & when they perform the MCCs. So, to minimize the fuel used in MCCs, I use the following technique. I'll use an example of a ship going from Earth to jupiter, then slings jupiter to get to Uranus. When to perform the MCCs? It's generally a good idea to perform a MCC when the time after orbit ejection/time after Previous MCC = Half the time left to reach your target. This means, let's say it takes 80M(million) seconds to get to jupiter, this means I would perform a MCC when time left to reach jupiter = 40M, 20M, 10M, 5M & so on until the I get close enough to jupiter for the PeA value to stop fluctuating. I guess most people already know this from Blixel's videos. Now, what tools to use to perform the MCC? I first set up the plan to reach jupiter along with the sling to Uranus in TransX and transfer the ejection burn values to IMFD using the deltaV program. This allows me to use the highly accurate Map program of IMFD. Then, I set up the plan in IMFD to get close enough to jupiter & execute the burn. When the time left to reach jupiter has halved, I correct the outward angle & Inclination angle in transX to reduce my Cl. App. value with respect to Uranus. Once that's done, I perform a MCC using transX, to get the R Inc value to 0 & Pe Ratio value to 1. Then, I open the IMFD map program & use the following settings. Now, I target Uranus in IMFD map program & even though I'm only halfway to Jupiter, I'm able to see my encounter at Uranus. Due to our MCC executed using transX just earlier, the PeA value at Uranus won't be way off. Then, I use the deltaV program of IMFD to perform corrections as per the IMFD map program, to correct my jupiter sling to uranus. This way, we can use the IMFD map program to execute slingshots planned using TransX more accurately. Now, back to this challenge, after 3 1/2 hours and patiently planning & executing more than 20 MCCs throughout my journey, I was able to get to Varuna without using the scenario editor to skip to the future. I even auto centered manually to save some RCS fuel. I still had a total of 160 dv left after the fly by. Time of flight was 19.85 years which is just under 20 years, even though my plan in TransX said it would take 19.55 years. I guess it's not surprising that transX was off by some 0.2 - 0.3 years, especially for long flights such as this one. The way we perform our MCCs affects our time to reach our target in that 0.2 - 0.3 year range. I think my TOF limit is just too tight, you'll need to know the optimum launch date as well as the optimum fuel to be burnt to achieve something like this. So I'm revising my TOF limit to 22 years. Also, 10 km altitude at Varuna seems too low, I went inside Varuna's mesh & came out of it from the other side. So I'm also revising the fly by altitude to 100 km. No change in the fuel limit because I'm allowing the use of scenario editor to skip to the future. Original post updated. Last edited by downloaderfan; 09-23-2016 at 08:27 PM.
 11-07-2016, 09:49 PM #24 flytandem Tutorial Publisher Saw this a few days ago but was busy over the weekend and couldn't get to it. Last night I gave it a try for a couple hours but was definitely going down the wrong path. I was thinking it was going to be something really exotic and ended up giving up. So about 30 minutes ago I started again and went at it in a much simpler manner. The KISS principle. I am pretty sure I know what downloaderfan has created. I like it. The reason I think I know is that I am pressing into both the fuel and time constrants at the same time. My current plan has a fairly comfortable fuel margin as long as I am careful with corrections, and comes in about 9 months before the 22 year limit. The tweaking of the plan that I did in the last couple of iterations showed a time savings that I believe that with further tweaking I could do an initial ejection burn a bit stronger and make the fuel remaining tighter yet still doable and it would cut more time off the plan meaning it might get under the 20 years as downloader wrote about. It is just too coincidental to not be very much like (or identical) to what the author planned and flew. I might fly it later this week but I much more enjoy just planning than flying.
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11-08-2016, 05:30 PM   #26
Orbinaut
The solution!!!!!!

Alright, now that flytandem has flown his planned trajectory and completed this challenge successfully,(I received a pm from him) I'm posting the solution scenarios. Inside the zip file is also a word file which consists of some explanation regarding the solution. Scenarios after all of my 24 MCCs are included, I know that's probably overkill, but it doesn't hurt either.
Attached Files
 Varuna intercept.zip (900.9 KB, 2 views)

 11-08-2016, 11:47 PM #27 flytandem Tutorial Publisher Doing pretty much the same thing. I opened your doc file and compared to my flight. When I flew it last night I took a screencapture of going across a saturn pole. Here's the dropbox link to the image... https://www.dropbox.com/s/pmo19prauy...16.16.png?dl=0 edit, a couple more images shwoing the arrival... I decided to aim directly at the center of Varuna. https://www.dropbox.com/s/pmnmb2nd9u...31.10.png?dl=0 It basically smacked into it and stuck in place. I did drop the gear and rotate level just before impact. https://www.dropbox.com/s/r7f8xbhf2f...36.25.png?dl=0 LOL Last edited by flytandem; 11-09-2016 at 12:00 AM. Reason: adding images
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 11-09-2016, 12:43 AM #28 boogabooga Bug Crusher Quote: Originally Posted by downloaderfan  My orbiter days are pretty much over by now... While I don't have Orbiter installed on my laptop any more... Oh my goodness, why? Even if you have limited time, was it necessary to remove from your laptop? It's a shame. You have such talent for trajectory planning.
 11-09-2016, 03:21 AM #29 downloaderfan Orbinaut Quote: Originally Posted by boogabooga  Oh my goodness, why? Even if you have limited time, was it necessary to remove from your laptop? It's a shame. You have such talent for trajectory planning. lol, while it's true I don't have orbiter installed on my laptop but...... My entire custom orbiter installation is stored in a rar file in google drive which means it's just a 15 minute download away from me. It's less of a time problem & more of an addiction problem. You can't get this good in trajectory planning without being badly addicted to it. I'm pretty sure that even flytandem was addicted to orbiter at some point, but since he's almost thrice my age, he has better addiction control capabilities than I do.(Not that addiction control has too much to do with age, it just differs from person to person) I can completely ruin my sleep & my entire next day if I find something good to work on for hours at night time in orbiter. So I try to stay away from it. Fun fact: I just downloaded orbiter again to reply to one of flytandem's trajectory on pm.
 11-09-2016, 06:41 PM #30 flytandem Tutorial Publisher Addiction? Guilt as charged. Night before last my wife asked me what I was doing. "Orbiter" I replied. "What?" she said. "You haven't done that in years." I do lurk the forum on occasion. It was nice to stumble onto this challenge. Thanks for creating and uploading it. cheers Last edited by flytandem; 11-09-2016 at 06:42 PM. Reason: grammar
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