Cool canards

[splashboom]

I built an SSTO and could not make it stable without a pair of canards on the nose. However I was sure they were gona fry on reentry, since they look rather flimsy and are at the very front (it enters kinda like the space shuttle). To my surprise they never even got an overheat bar. The nose, cabin, and some of the engines did overheat - no more than 3/4 bar - but never the canards, in more than 10 reentries now.

Is there a reason(aerodynamic?) why they should stay cool? The max temp on them is 2400, less than the 2700 on the cockpit, which in turn did get overheated.

Thanks!

[eddiew]

IIRC, thermals get distributed in KSP; the canards may be dumping their heat into the cockpit.

Logically they also have a very high surface area to volume ratio and should be able to radiate more efficiently than a cylinder/cone. And I guess they present a relatively small profile to the airstream, especially if you're coming in prograde. The cockpit has a 1.25m radius, no matter how streamlined it is. The canard is a knife edge.

[splashboom]

@eddiew, you make good points. It is not exactly prograde, rather 20 degrees from~. My understanding of hypersonics is that a layer of plasma forms around blunt objects, the blunter the further away. So the cockpit would keep the radiating plasma further away(and deal with the radiation) while any smaller and aloft parts might be closer to it, or right in it. So I doubt Starship would get away with having something like that 'in the wind' .. but who knows. Then again not sure how much of the physics are modeled in ksp (see lift mechanics for instance). Regardless, the re-entry flames are a show to watch

[eddiew]

7 hours ago, splashboom said:

My understanding of hypersonics is that a layer of plasma forms around blunt objects, the blunter the further away.

You are quite possibly right for reality; but I'm not sure KSP does this. It isn't the most realistic of atmospheric sims. I remember the days of drag cubes and how it didn't really matter whether you put a nose cone on your rockets 

But if you're looking for the most realistic behaviours, you might want to try FAR:

 Side note; I think your SSTO is unstable because it seems to be quite short and wide. Your trailing control surfaces don't have a lot of leverage distance from the CoM, and likely don't give you very much assistance. Adding canards at the front feels like brute forcing the aerodynamics with control authority. Which often works 

[Rocket Witch]

Many aircraft parts have higher-than-normal emissive constants set in their configs, which lets them radiate heat away more quickly. I think the default value is 0.6. Wing surfaces (like your canards) and radiators have 0.95; Mk3 bodies have 0.9; Mk2 bodies and rocket engines have 0.8. Mk1 bodies don't have a nonstandard emissive constant.

Crewed parts have relatively low internal max temps. With all other things being equal, the overheat warning always appears earlier for them based on heat transferring to the inside of the part and reaching a higher fraction that lower max temp value. This isn't realistically a concern unless you construe a scenario that maintains a specific heat load (enough to cook the crew, but not enough to destroy the part from the outside) for a long time.

Edited December 5, 2021 by Rocket Witch

[Mahnarch]

On 11/27/2021 at 8:55 PM, splashboom said:

 Regardless, the re-entry flames are a show to watch

The re-entry flames are how I sold a couple of friends on the game.