[1.0] Is it normal for my rockets to always "catch on fire" during ascent?

[A_name]

Practically all my rockets begin showing reentry effects during ascent and by the time I reach Ap >70km they will have become a huge fireball. Seems a bit odd since this doesn't happen to real rockets, but maybe I'm doing something wrong. Is this normal?

Edited April 30, 2015 by A_name

[arkie87]

Practically all my rockets begin showing reentry effects during ascent and by the time I reach Ap >70km they will have become a huge fireball. Seems a bit odd since this doesn't happen to real rockets, but maybe I'm doing something wrong. Is this normal?

how fast are you going and at what altitude (not Ap)

[WOODY01]

Practically all my rockets begin showing reentry effects during ascent and by the time I reach Ap >70km they will have become a huge fireball. Seems a bit odd since this doesn't happen to real rockets, but maybe I'm doing something wrong. Is this normal?

You are just going to fast in the lower atmosphere. Real rockets and planes will heat up if traveling fast enough in an atmosphere.

[EtherDragon]

Speed kills, slow down a bit on your ascents!

[Starwhip]

Short answer: Yes.

Long answer: You're probably going a wee bit too fast. Mach effects are OK, not sure about reentry effects.

[Blu_C]

Most likely your rocket is simply traveling too fast for the altitude it is at. Above around 10km (sea level) Mach effects turn into re-entry effects. So long as parts aren't actually exploding due to heating you are fine.

If it is bothering you try throttling back slightly, as you may be over-thrusting. It isn't a huge problem, but does make your ascent less efficient due to drag losses (ideally your craft travels at exactly terminal velocity while in atmosphere, though in practice such precision isn't at all necessary for most KSP rockets).

[Anquietas314]

Mach effects are OK, not sure about reentry effects.

In my experience on default settings reentry effects during launch mean you're getting dangerously close to exploding. I have had a few rockets make it with minor flames, but so far none survive when it gets more severe.

[A_name]

Thanks for your replies.

Do we know what the terminal velocity is in 1.0?

[xXIndestructibleEVAXx]

It depends on the object. Terminal velocity is when gravity is equal to drag, so a feather has a higher terminal V than a hammer. That's the only reason a feather falls slower than a hammer.

[Gaarst]

Thanks for your replies.

Do we know what the terminal velocity is in 1.0?

You can use Kerbal Engineer for 1.0, I guess the terminal velocities have been adapted to the new aerodynamics. But from what I remember, terminal velocity gets very high very fast. You can get "reentry effects" at 30% of terminal (according to Kerbal Engineer)

[Anquietas314]

Do we know what the terminal velocity is in 1.0?

Since 1.0 has a much more realistic aerodynamic model, there is no single terminal velocity - it depends on the shape/orientation/etc of a given rocket; the pointier the nose, the faster it can fall under gravity .

[NathanKell]

AeroGUI can estimate your terminal velocity in your current orientation.

[FlipNascar]

Since 1.0 has a much more realistic aerodynamic model, there is no single terminal velocity - it depends on the shape/orientation/etc of a given rocket; the pointier the nose, the faster it can fall under gravity .

Actually... Not necessarily. You want a tear drop shape, that in principle is the most drag efficient. Of course cross sections blah blah blah. Why else does water fall in that shape? Here's what Nasa has to say: http://exploration.grc.nasa.gov/education/rocket/shaped.html

[Anquietas314]

Actually... Not necessarily. You want a tear drop shape, that in principle is the most drag efficient. Of course cross sections blah blah blah. Why else does water fall in that shape? Here's what Nasa has to say: http://exploration.grc.nasa.gov/education/rocket/shaped.html

That's the way it sometimes works in the real world, yes, however we're talking about KSP's aero model. I set up a simple test rig:

Test rig:

The airbrakes are there to stop the rig from getting too far out of the atmosphere - we're after terminal velocity, not re-entry effects! Also the SRB's throttle limiter is set at 50% - just to stop the thing exploding on the way up

Basic nosecone (roughly tear shaped):

This one made it to about 20km before burning out, after separating on the way down it peaked at around 255m/s:

Advanced nosecone (more pointy):

This one peaks at around 30km without the airbrakes, and on the way down reached just over 322m/s, making it the clear winner:

Both tests reached terminal velocity prior to taking the screenshot - they'd started slowing down due to increasing drag from the atmosphere. There is of course the slight detail that the pointier nosecone is quite a bit heavier, but given the pointier nosecone gets higher on the way up I don't think that matters much here.

Edited April 29, 2015 by armagheddonsgw

[A_name]

Thanks you guys!