Something wrong with aerodynamic drag in 1.04

[Amorto]

Hi everyone! I did a little bit of aerodynamic testing yesterday. And my test results are confusing.

For testing purposes I used very simple craft as shown on this image. Parts in the vehicle: 1 RT-10 "Hammer" Solid Fuel Booster, 4 Basic Fins and 1 Probodobodyne OKTO2 (hidden inside booster with offset tool). I used almost stock version of the game w/o any gameplay tweaking mods. I verified game cache before tests and everything was fine.

Results (approximate with margin of error about 3-5%):

[TABLE=class: grid, width: 500]

[TR]

[TD]Delta-v

[/TD]

[TD]TWR(surf)[/TD]

[TD]Drag[/TD]

[TD]Altitude (km)[/TD]

[TD]Nose part

[/TD]

[/TR]

[TR]

[TD]2466\2828[/TD]

[TD]6.35[/TD]

[TD]1641[/TD]

[TD]49[/TD]

[TD]No cone

[/TD]

[/TR]

[TR]

[TD]2420\2776[/TD]

[TD]6.30[/TD]

[TD]1879[/TD]

[TD]26[/TD]

[TD]Aero cone[/TD]

[/TR]

[TR]

[TD]2355\2702[/TD]

[TD]6.23[/TD]

[TD]1580[/TD]

[TD]42.6[/TD]

[TD]Adv. aero cone[/TD]

[/TR]

[TR]

[TD]2450\2811[/TD]

[TD]6.34[/TD]

[TD]1440

[/TD]

[TD]69

[/TD]

[TD]Small nose cone

[/TD]

[/TR]

[TR]

[TD]2195\2581[/TD]

[TD]6.02[/TD]

[TD]1357

[/TD]

[TD]46[/TD]

[TD]Tail connector type A

[/TD]

[/TR]

[TR]

[TD]2428\2785[/TD]

[TD]6.31[/TD]

[TD]1634[/TD]

[TD]44[/TD]

[TD]Shock air intake (open and closed results are the same)

[/TD]

[/TR]

[TR]

[TD]2242\2572[/TD]

[TD]6.09[/TD]

[TD]1488 [/TD]

[TD]39[/TD]

[TD]Protective shell 1.5m (pointy shape)

[/TD]

[/TR]

[/TABLE]

Isn't it strange that rocket had a better perfomance without nose cone? And why small nose cone is so effective?

[Red Iron Crown]

Welcome aboard!

On such a small rocket the mass of the nosecones trump the reduced drag (except for the very lightest nosecone). Try adding some inert payload so that initial TWR is 3 or less, you'll see bigger benefits from the other cones.

Another factor is that such a high TWR rocket will get out of the thick atmosphere quite quickly, meaning that drag effects are not as significant. An alternate test might be to put the rocket on launch clamps at 45 degrees and see which ones go the furthest, that way the atmospheric effects are more significant.

[Right]

Old post I know, but the pretty chart deserves the best possible answers.

The reason this is happening is because you're mounting you're nosecone to a Probodobodyne OKTO2 (0.625m radius). As a result, the only nose cone with a 0.625 radius that you tested yielded the best result. This is because of the way drag occlusion works. Even if you used the offset tool to get the cone right on top of the booster, the drag acts like you didn't offset anything.

Repeating you're tests with a 1.25m radius probe core would furnish more realistic results.