SurClaro Flight Simulator Resources

No, this is indeed no tutoral, it is a basic question asked by the Rhythmosaur. You are not dreaming! Embarassed

I feel confused about figuring out my groundspeed:
Ground speed is the speed telling how fast I move related to the surface, not related to the air.

When I watch my GPS, it has a GS indicator that should tell me exactelly about this figure. But when I take a look at my NavLog, I pretty often find much higher numbers there, usually about 100kt more than indicated on the GPS when flying an airliner at cruise altitude.

I already verified that the same units - american system - are used, so it could be no matter of different units. Anyone outthere who could open my eyes?

The Rhythmosaur

Posted: Fri Mar 26, 2004 3:27 am Post subject:

Maybe the NavLog does not calculate atmospheric winds?

Posted: Fri Mar 26, 2004 3:29 am Post subject:

I, the almightly lortiawhak has come to the rescue to open your eyes! Ta Da! Laughing

I have a solution!
Don't look at that GPS incicator nav log thingymagigy.
just look at the airspeed indicator! Shocked

A novel idea!!
As long you are between 0 and 15 knots, you should be fine!
Hope this helps!
I, the almighty lortiawhak superman has just helped another-the Rhythmosaur! I must now go help another fellow simmer in the perilous depths of confusion and question!
So Long!
Tra La La La!

The almighty Lortiawhak

Posted: Fri Mar 26, 2004 5:40 am Post subject:

I have noticed such differenes in the past with older versions of FS. You could fly a known distance in a known time and then figure your ground speed out over the distance. A hundred knots is pretty serious. It should not be hard to figure out which is more accurate. Alternately, if you have a flight computer, (the trusty E-6B, or one of its dirivitives,) you can get a good estimate. Its not 100% accurate, but you would be suprised how close it comes. Shocked

NOTE: This was edited to correct the spelling of "Known distance."

Posted: Fri Mar 26, 2004 5:59 am Post subject:

@ lortiawhak: Rolling Eyes

I am not a great light in physics, indeed my medical studies crashed after missed approach on physics. But the airspeed indicator, you I-just-had-a-clown-for-breakfast-Joker, does NOT show the GROUNDSPEED, but the AIRspeed! That's why they call it AIRspeed indicator. When you face 200kt headwind and your AIRspeed indicator shows 200kt, then your GROUNDspeed is ZERO. The Aircraft flies with 200kt but actually DOES NOT MOVE! You hover! In older days it even happened to some airliner captains that the British Coast they just left half an hour ago just appeared again because they faced headwind and were indeed moving BACKWARDS!

Hope you learned this lesson. Or should I draw you a map on it Twisted Evil

?, almighty?

@Insured Disaster: So you think it's kind of a bug? If so, what data you'd trust more? GPS or NavLog?

The Physi - I mean Rhythmosaur

Posted: Fri Mar 26, 2004 6:22 am Post subject:

Thats why I suggested you test it for yourself. I had some addons for FS2000 that I played with. They had Flight Management Computers (FMC's) and GPS's and they showed different speeds. I cant remember which was more accurate or even if the difference was enough to care. I would probaly go with the GPS for starters, as it is a MS default program, but you might find that the Nav program you have is more accurate. Cant say I know. Perhaps there is another user of both programs out here? Shocked

Posted: Fri Mar 26, 2004 6:49 am Post subject:

The thing is that I want to provide somewhat reliable data when I submit my reviews. Therefore, I need the ground speed.

Posted: Fri Mar 26, 2004 6:52 am Post subject:

Well, in that case, go with the GPS. Even if it is wrong, perhaps being on the same note as the rest of us will keep people from wondering why they can't get the same results as you could. Shocked

Posted: Fri Mar 26, 2004 10:40 am Post subject:

An add-on program that I have used off and on in the past is the Garmin series (there is a 430 and a 530) that seems to be relatively accurate. The downside to this add-on is that it will negatively impact frame-rates and is complicated to learn to use. I don't remember the link I used to find it, but will do a search if anyone is interested. BTW, in the 60's, Air Force pilots used to take off on a windy day in a L-10, throttle back shortly after leaving the ground, and then land back where they started without ever making any turns. Used to drive the controllers nuts.

Posted: Fri Mar 26, 2004 3:37 pm Post subject:

sorry

I didn't mean it
but air speed should be...forget it.
I think its a bug. you should get a new copy.
-lortiawhak

ps: the almighty lortiawhak has died Sad

Posted: Fri Mar 26, 2004 3:58 pm Post subject:

I dont know if it is a "bug" in the typical sense of a PC bug. Perhaps more like a case of improper conversion? What is this program and which rock should I overturn to find it? I would like to try this thing out and see what I get. Is this FS 04 or 02? I only have 04. But neverthe less, I think the author might have, if it is really innacurate, programed some sort of conversion wrong, when it converted airspeed to GS. I dont know though. I would like to try it out. Shocked

By the way, Lortiawhak, do you have your FS realism settings set to display indicated or true airspeed. I think I know what you are saying. True airspeed is the first step in finding the ground speed, then you have to factor in the wind. But the rest of us (me anyway, and mostlikely the Rhythmosaur) are using "indicated" airspeed, for higher realism. For us, ground speed and airspeed are in no way all that close to one another at high altitudes. If you havent already, set the realism settings to "indicated airspeed." Thats the thing that the flying part of a pilot cares about. Its the navigating part of the pilot,(and the passengers too,) that care about groundspeed.

Yes, flyrcoyle, I do have an interest in the program, though I dont know if I would use it much. My FPS is already pretty low. Some of us in pursuit of the highest realism might wish to see if they can handle this extremely expensice piece of equipment. Shocked

Posted: Sat Mar 27, 2004 3:36 am Post subject: Dont know yet,

but I've been playing around with FSFlightmax, as soon as I have discovered all of its jewels I'll try to give a report. It is similar to the Garmins but seems to have more functionality, so far I havent noticed an appreciable drop in frame rates(FS2k2, Athlon1800xp, ATI Rage 128pro, Logitech Wingman Force). Will advise, groundsquirrel out.

Posted: Sat Mar 27, 2004 5:14 am Post subject:

The Garmin instruments may be downloaded by doing a search for "Garmin" or filename fsgarmin. I'd recommend the Garmin search as it came up with a Garmin 500 GPS system.

Posted: Sat Mar 27, 2004 6:20 am Post subject:

try guessing, it might be more reliable than all of your garmin gps navlog indicator stuff. Laughing

assume your right.

Posted: Sat Mar 27, 2004 9:38 pm Post subject:

There is one other way you can find your groundspeed, figure it manually. We used this method for years in the real world. Most pilots use the E6b calculator which can be found in most good pilot supply shops or you can use an online version I found last night(http://www.csgnetwork.com/e6bcalc.html).