BaseSync: what is "diff"?

[rocketman768]

I was going to use BaseSync to help me land at brighton beach. My orbit passes right over the beach, so I thought when I brought up BaseSync, it would have the normal "Time: Dist: Heading:" stuff with the lowest entry in the "Dist:" column being close to zero. However, all I have are 2 columns that say "Time: Diff:". What the heck is "Diff:"? It lists degrees also instead of meters, and the entries in that column are 74.92, 73.85, 72.77, 71.70 (all with a degree sign).

What the heck is this?

 

[rocketman768]

And also as a side note, I can never use aerobrake mfd for descending to the moon. Whenever it's pulled up and I start to do the retrograde burn, orbiter crashes.

 

[mrspacely]

And also as a side note, I can never use aerobrake mfd for descending to the moon. Whenever it's pulled up and I start to do the retrograde burn, orbiter crashes.

i believe you need an atmosphere for aerobraking...

 

[rocketman768]

i believe you need an atmosphere for aerobraking...

Um, aerobrake does more than help you with aerobraking...but thanks for the extremely patronizing comment anyway.

 

[Andy44]

Aerobrake has a bug which causes it to crash if you use it on an airless body. I've tried it myself. Base Sync works better for that.

 

[tblaxland]

Aerobrake has a bug which causes it to crash if you use it on an airless body. I've tried it myself. Base Sync works better for that.

I noticed that the author, Gregorio Piccoli, was kind enough to provide source code so I had a bit of a look.

The AtmBrake::Update function is a monster (1243 lines!) and the comments are in another language (Italian, I think) but I think I tracked the error down to a divide by zero that is not being caught:

void AtmBrakeMFD::Update(HDC hDC){
//...
      double dynp=Ship->GetDynPressure();
//...
      double SCl=Ship->GetLift()/dynp;
//...
}

Other places there is code to check for dynp>0 or some similar parameter.

I can't test this right now because I don't have my compiler here setup for debugging but I'll try and have a look at it over the weekend. If anyone else wants to have a look in the mean time, feel free .

Does anyone know if the author still active? Also, I noticed jarmonik is listed as the original developer and there is also code included from Chris Knestrick (presumably just for the attitude control since he was the original author of AttitudeMFD). A twisted history, this MFD has...

 

[pattersoncr]

I was going to use BaseSync to help me land at brighton beach. My orbit passes right over the beach, so I thought when I brought up BaseSync, it would have the normal "Time: Dist: Heading:" stuff with the lowest entry in the "Dist:" column being close to zero. However, all I have are 2 columns that say "Time: Diff:". What the heck is "Diff:"? It lists degrees also instead of meters, and the entries in that column are 74.92, 73.85, 72.77, 71.70 (all with a degree sign).

What the heck is this?

"Diff" shows the difference in longitudte at the place where your orbital plane crosses the latitude of the landing site. This is what BaseSynch displayes when you have it set for "Lattitude" mode as described on pg 2 of the manual. What you want is "Closest Passage" mode, as described on pg 3. you switch between modes using [Shift-E] Just like it says on pg 1.

 

[ar81]

And also as a side note, I can never use aerobrake mfd for descending to the moon. Whenever it's pulled up and I start to do the retrograde burn, orbiter crashes.

I use Map MFD for that since it is airless.

If atmosphere is present impact point will not be the impact point that is shown in Map MFD, for air will make you brake.

 

[Andy44]

Map MFD doesn't have fine enough resolution. And Aerobrake MFD will indeed show you the impact point by modeling zero drag (provided the /0 error gets fixed).