how do you design a good glider?

[endl]

ive read the thread by keptin in regards to basic aerodynamics but it doesnt really mention much about what makes a good glider, is there a general rule about how much wing spread you need, or does KSP have some king of magic ratio that will determine how much lift you get just from the wings?

Edited September 22, 2014 by endl

[Alshain]

Are you using any of ferram4's addons? Gliders in KSP stock are well, different. Not so much gliders as much as they are infinite propulsion devices or infini-gliders. If you use FAR or NEAR it removes the ability to create such devices that break the laws of physics.

[Redshift OTF]

Each wing part or control surface has a lift rating you can see by right clicking the item in the VAB/SPH. The total of all these parts is used in a calculation with the weight to give you your lift rating for the craft although I have no idea what this calculation is.

[endl]

Are you using any of ferram4's addons? Gliders in KSP stock are well, different. Not so much gliders as much as they are infinite propulsion devices or infini-gliders. If you use FAR or NEAR it removes the ability to create such devices that break the laws of physics.

stock aero

Each wing part or control surface has a lift rating you can see by right clicking the item in the VAB/SPH. The total of all these parts is used in a calculation with the weight to give you your lift rating for the craft although I have no idea what this calculation is.

i know about the lift rating, im after the calculation or a best guess estimate of the mass to lift ratio

[GoSlash27]

Not so much. It's all about lift vs. drag and mass. Unless you're looking for an infiniglider, in which case the rule is "moar control surfaces".

Lift is a fixed coefficient for each wing. Drag is composed of 2 parts; induced and parasitic. Induced is fixed, while parasitic is a function of mass (and almost nil for most wings).

Mass is like any other part.

The key to efficient gliding is high lift/drag and careful balancing of the CoG. There's no sweet spot in there AFA lift/mass ratio. The higher the better.

Best,

-Slashy

Edited September 21, 2014 by GoSlash27

[endl]

Not so much. It's all about lift vs. drag and mass. Unless you're looking for an infiniglider, in which case the rule is "moar control surfaces".

Lift is a fixed coefficient for each wing. Drag is composed of 2 parts; induced and parasitic. Induced is fixed, while parasitic is a function of mass (and almost nil for most wings).

Mass is like any other part.

The key to efficient gliding is high lift/drag and careful balancing of the CoG. There's no sweet spot in there AFA lift/mass ratio. The higher the better.

Best,

-Slashy

so is there a preferred ratio for lift/drag or do you just want to be in the positive? in which case is there a mod that tells you total drag?

[Laie]

Mechjeb can display somehing with drag; and I bet KER can, too. But I never really bothered. Every plane I ever built also happened to be a good glider, in the sense that I needed to actually FORCE them down for landing.

[Geschosskopf]

ive read the thread by keptin in regards to basic aerodynamics but it doesnt really mention much about what makes a good glider, is there a general rule about how much wing spread you need, or does KSP have some king of magic ratio that will determine how much lift you get just from the wings?

If you mean a plane that glides a long way without power of any kind, as opposed to the glitch/cheat "infini-glider", then what you want is the best L/D you can get. This is basically the slope of its descent path because that's what gliders do---they go down. To maximize L/D, you want as much lift and as little weight as you can put into 1 plane of practical size. That's pretty much all there is to it, apart from the usual balancing of CoM and CoL.

Be aware that there are no air currents in KSP, so you can't climb in thermals like real gliders do. Thus, any glider needs some form of propulsion to get up in the air to start with. This can be a conventional engine or, if playing stock, the glitch/cheat "infini-glide" thing.

Also be aware that there are no stock airbrakes or spoilers so planes that glide very well can be difficult to land. They just don't want to quit flying and you have to force them down, but this can inadvertently cause some "infini-glide" propulsive effect from the repeated control inputs. If you use FAR, you can't infini-glide even accidentally, and you can put spoilers on the plane to force it down without it gaining speed.

[endl]

yea i just wanted to get a more accurate measure of how much wing i need so that i can land without engines.

[GoSlash27]

so is there a preferred ratio for lift/drag or do you just want to be in the positive? in which case is there a mod that tells you total drag?

You just want to be in the positive, the more the better. I'm not aware of any mods that give total drag.

Best,

-Slashy

[mhoram]

stock aero

i know about the lift rating, im after the calculation or a best guess estimate of the mass to lift ratio

You might find some info on that issue in this thread:

http://forum.kerbalspaceprogram.com/threads/29788-How-to-calculate-lift

so is there a preferred ratio for lift/drag or do you just want to be in the positive? in which case is there a mod that tells you total drag?

In Stock KSP drag is directly proportional to the mass of the ship, so you do not have a big influence on the mass/drag ratio.

Edited September 22, 2014 by mhoram

[Scarecrow88]

In the stock game, I have found that all of my aircraft designs fly perfectly well with the engine off, or at least the ones that fly well with the engines on do. I've never bothered looking at any of the data for my craft, so have no idea what the typical mass or lift numbers are. If you design a well balanced craft that flies well under power, you shouldn't have any problems with it when you turn the engines off.

[endl]

In the stock game, I have found that all of my aircraft designs fly perfectly well with the engine off, or at least the ones that fly well with the engines on do. I've never bothered looking at any of the data for my craft, so have no idea what the typical mass or lift numbers are. If you design a well balanced craft that flies well under power, you shouldn't have any problems with it when you turn the engines off.

thats not really true, the total glide power of your craft results in an extended landing range and allows for a more controlled approach speed