Are the last two fields the min and max transit time in days?

It's not working for me. Is it Java?

It works for me the first time I hit "Plot C3". If I change some parameters and hit that button again it doesn't work right (doesn't update the image). I'm using Chrome on Windows 7.

I've made several attempts but haven't been able to get it to work.

I was trying this on iOS and it didn't work, which isn't a surprise. I'll try it with a real computer.

Quote from: Hop_David on 01/18/2014 05:17 pmI've made several attempts but haven't been able to get it to work.Which OS/Browser are you using? Which steps did you take and/or where/how did it fail? (to be sure; you had valid input data in all fields?)

Quote from: kfsorensen on 06/09/2011 02:13 pmI've just been playing around with the trajectories and see a few interesting things--when you look "down" on them as we're used to doing, they look wrong. Very non-Hohmann transfer. But when you look at them obliquely you can see why--they always "want" to arrive when Ceres is crossing its "line-of-nodes" which is where its orbital plane intersects with the Earth's orbital plane (the ecliptic).The earth at departure, Ceres at Arrival, and the sun form the corners of a Lambert space triangle. The transfer ellipse must be coplanar with this triangle.A Hohmann transfer traverses 180 degrees. Since Ceres' orbit isn't coplanar with the earth, this forces the transfer orbit to be at right angles to both earth's orbit and Ceres' orbit.This geometry that forces a polar orbit is what I believe accounts for the diagonal streak through pork chop plots.I tested this notion by clicking on the diagonal on one of your pork chop plots and looking at the trajectory:It does indeed look like the departure and destination are 180 degrees from one another which forces a polar orbit at 90 degrees to both departure and destination orbit.I believe it's much better to depart on a Hohmann coplanar with earth's orbit. Then at the line of nodes, do a plane change burn and continue onto the destination:I like to call this a folded Hohmann transfer. Depending on where the line of nodes folds the earth to Ceres Hohmann, plane change can range from 6.7 km/sec to 2.4 km/sec.The 6.7 km/sec plane change is at perihelion of the Hohmann. This is the 10.5 degree plane change between two 36 km/sec vectors. But the perihelion is at earth departure. So V infinity would be the difference between a 30 and 36 km/sec vectors at 10.5 degrees to each. You would also enjoy an Oberth help if you're launching from LEO. So there is a benefit if your launch is at the line of nodes.However, I believe your application exaggerates the benefits of launching at the line of nodes since it doesn't allow for midcourse plane changes.

I've just been playing around with the trajectories and see a few interesting things--when you look "down" on them as we're used to doing, they look wrong. Very non-Hohmann transfer. But when you look at them obliquely you can see why--they always "want" to arrive when Ceres is crossing its "line-of-nodes" which is where its orbital plane intersects with the Earth's orbital plane (the ecliptic).

I moved my mouse about until hovering over approximate Hohmann departure and arrival dates: March 12 2016 and November 27 2016. As expected, this was in the middle of a dark diagonal stripe. Arrival velocity was given as 20635m/s. As expected, the chart seems to say steer clear of Hohmann windows.

I've made several attempts but haven't been able to get it to work.I have a general complaint against apps based on Lambert iterations. For a Hohmann orbit the departure and arrival points of a Lambert space triangle differ by 180º. If inclination of destination planet isn't zero, this forces the heliocentric transfer orbit to be polar. This transfer orbit is at 90º to earth's orbit and usualy around 90º to the destination planet's orbit.A 90 degree plane change is huge. So usually pork chop apps like this discourage Hohmann transfers.The 90 degree plane change can be largely mitigated by a midcourse burn or a broken plane transfer. I wish online pork chop apps would have this caveat. I talk about this more at Deboning the Porkchop Plot.

If I understand you correctly, the lamberts method does not handle the Hohmann edge-case, however the areas outside the black stripes are still correct? Then I should have a notice of this limitation.

However, does it matter, at least in case of earth->mars? I have a question for you; would the total delta-v requirement for your proposed 'ideal' trajectory be less than the alternative trajectories around the stripe? 6.7 to 2.4 km/s plane change sounds a bit expensive?Looking at NASAs MAVEN, they seem to have followed a trajectory given by solving lamberts problem, rather than a Hohmann transfer.

What is the advantage of your proposal, to also consider Hohmann transfers?

I wish online pork chop apps would have this caveat. I talk about this more at Deboning the Porkchop Plot.

The app is correct. It's just that a two burn ballistic trajectory often is far from the least delta V path. If the line of nodes is distant from launch, 3 burns (Departure burn, mid course plane change, arrival burn) can give a path with a substantially lower delta V budget. See this broken plane transfer pdf.

The virtue of a Hohmann is that the transfer orbit is tangent to both departure and destination orbits. With parallel velocity vectors, no direction change is needed only speed change.Mars' orbit is noticeably elliptical. So a transfer orbit tangent to both earth and Mars orbit sometimes differs from an 180 degree Hohmann from one circular orbit to another.

From the Spaceflight 101 Maven Mission Profile here is a pic of the Maven path:Notice the transfer orbit is tangent to departure and destination orbits. Little or no delta V is needed for direction change, only speed change.Also the launch window for this tangent orbit was pretty close to Mars. ascending node: 50º. Earth crosses Mars' ascending node in early to mid November.

Quote from: malu5531 on 01/19/2014 01:05 amWhat is the advantage of your proposal, to also consider Hohmann transfers?An 8 month Hohmann transfer is only an approximation based on the simplifying assumption of a circular Mars orbit. Since Mars orbit is an ellipse, tangent transfer orbit can be shorter or longer than 8 months. The transfer orbit can be more or less than 180 degrees, but in that neighborhood. The advantage of tangent transfer orbits is less delta V.

I guess in general it's important to make sure arrival velocity is tangential to the destination orbit?