Problems with drag

[Alshain]

I feel like there is still an issue with drag, I just can't track it down. In the past I thought the new aero was fine, but I'm starting to have doubts. Those of you who are familiar with me, know I'm a rather successful FAR user in pre-1.0, so I know how to launch a rocket. However, the drag seems a bit, unpredictable in 1.0.2. I've had plenty of rockets work just fine that were un-aerodynamic pieces of trash, and then a streamlined rocket like this one won't even go straight up without flipping over. I just feel like it just isn't as intuitive as it should be, certainly not as intuitive and predictable as FAR. With FAR if you didn't go too far off the prograde and didn't have too much forward drag then the rocket would do fine, but with 1.0.2 it just doesn't seem to be the case. An aerodynamic rocket should not flip when it is pointed at a perfect prograde, but it does.

I'd love to figure out a reason this occurs, has anyone figured anything out as to why a seemingly well built rocket won't fly when others do just fine? Are fairings actually shielding from the air? That is kind of what it feels like, as if the drag from the cargo was pulling it around.

EDIT: (Oops, this was supposed to be in Gameplay)

Edited May 25, 2015 by Alshain

[Hcube]

The thing that bothers me most with drag now is how it is modeled in relation with part occlusion. Try making a cluster of a few LV-T30 under a 2.5m core (say an orange tank) and activate the aerodynamic vectors overlay. You will get a ton of drag due to cubic octagonal struts and engines, and you won't need any fins even if your rocket is very un-aerodynamic and not streamlined. you can have just a few orange tanks, a big cluster, and a HUGE bulky and fat fairing on top, and it'll fly straight.

EDIT : about your question about the fairings : they actually add more drag than what the average payload inside would add if left unshielded. That could answer some of your problems. Not to mention they are crazy heavy !

But let's not start another fairing complaint thread here

Edited May 25, 2015 by Hcube

[Alshain]

EDIT : about your question about the fairings : they actually add more drag than what the average payload inside would add if left unshielded. That could answer some of your problems. Not to mention they are crazy heavy !

But let's not start another fairing complaint thread here

Not a complaint, that is good to know and I didn't realize that, but it is unfortunate since making streamlined rockets fly right is what most people who wanted new aero were excited about. So it sounds like we aren't much different than 0.90. Leave the nose cones and fairings off, they make it worse.

EDIT: Yep, removed the fairing and it flew right into space. That is just really unfortunate.

Edited May 25, 2015 by Alshain

[Eric S]

One thing I see about that rocket that stock aero doesn't handle well is that fairing base (or decoupler?) that's smaller than the rest of the craft. Basically, the only occlusion that stock aero handles is fairings/cargo bays and the stacked parts, and it is aware of it if you stack a small part on a large part (wasn't the case in 1.0, that changed in 1.0.1 I think). So the stock aero basically sees the back of the fairing as creating turbulence because it's almost a flat cutoff (the back of a craft has aerodynamics, not just the front), and then down below it, you've got a 2.5 meter fuel tank where only a quarter of it is occluded, so even more drag. nuFAR wouldn't have a problem with that since it won't see airflow between the two "flat" surfaces, but stock aero does.

[RocketPilot573]

The thing that bothers me most with drag now is how it is modeled in relation with part occlusion. Try making a cluster of a few LV-T30 under a 2.5m core (say an orange tank) and activate the aerodynamic vectors overlay. You will get a ton of drag due to cubic octagonal struts and engines, and you won't need any fins even if your rocket is very un-aerodynamic and not streamlined. you can have just a few orange tanks, a big cluster, and a HUGE bulky and fat fairing on top, and it'll fly straight.

EDIT : about your question about the fairings : they actually add more drag than what the average payload inside would add if left unshielded. That could answer some of your problems. Not to mention they are crazy heavy !

But let's not start another fairing complaint thread here

This, basically all complicated craft have huge amounts of drag, shape is 100% ignored, literally.

[Alshain]

One thing I see about that rocket that stock aero doesn't handle well is that fairing base (or decoupler?) that's smaller than the rest of the craft. Basically, the only occlusion that stock aero handles is fairings/cargo bays and the stacked parts, and it is aware of it if you stack a small part on a large part (wasn't the case in 1.0, that changed in 1.0.1 I think). So the stock aero basically sees the back of the fairing as creating turbulence because it's almost a flat cutoff (the back of a craft has aerodynamics, not just the front), and then down below it, you've got a 2.5 meter fuel tank where only a quarter of it is occluded, so even more drag. nuFAR wouldn't have a problem with that since it won't see airflow between the two "flat" surfaces, but stock aero does.

Aerodynamically, that makes no sense. The fairing base is the same size as the tank below it, the only difference is the probe core. But there isn't another choice in probe cores because Squad put all the more appropriate cores end of the tech tree instead of with the sized parts they belong to (2.5m in this case). Either way, it shouldn't matter, even turbulence doesn't make 90 degree turns, that fairing base is close enough to the tank below it that it shouldn't be caught in the air. If it is, that is broken and it is pretty much the same as 0.90 where all parts on the craft create drag regardless of where they are.

[The Yellow Dart]

It looks like that rocket goes down to 1.25m before going back up to the 2.5m fairing. I think the game registers that a basically putting a 1.25 nosecone on an orange tank, ontop of the drag of the fairings above it. Have you tried flying it without that gap?

[Alshain]

It looks like that rocket goes down to 1.25m before going back up to the 2.5m fairing. I think the game registers that a basically putting a 1.25 nosecone on an orange tank, ontop of the drag of the fairings above it. Have you tried flying it without that gap?

As I mentioned, not possible because we don't have appropriate probe cores until endgame (or end tree anyway). I don't think that is the problem anyway, I removed the fairing and the problem went away. The cargo above it is 2.5m.

[Vanamonde]

Moved to gameplay, by (implied) request.

[Alshain]

Moved to gameplay, by (implied) request.

Thank you.