10M Inflatable Heatshield

[Reinhart Mk.1]

So (surprise surprise) here's another Eve post, but it's short. I've noticed i dont really have to inflate the heatshield when coming in for rentry (entry?). I'm at a peri of 67 as well... sooo do you not have to inflate it or is it best to inflate it when you're REALLY coming into atmosphere?

[Reinhart Mk.1]

sorry if this is the incorrect section but i have some footage of this

 

[Gargamel]

Moved to Gameplay Q's

This is a new concept to me....

[The Aziz]

Maybe, but when inflated, that thing works like a Mary Poppins' umbrella or something, slowing the craft down waay below terminal velocity in lower atmo, probably saving your craft.

[Aeroboi]

11 hours ago, Reinhart Mk.1 said:

So (surprise surprise) here's another Eve post, but it's short. I've noticed i dont really have to inflate the heatshield when coming in for rentry (entry?). I'm at a peri of 67 as well... sooo do you not have to inflate it or is it best to inflate it when you're REALLY coming into atmosphere?

I did some tests using heat protective cross section solutions for Eve re-entry vessels. My findings are that a deflated 10m heatshield has relatively low drag but more so then a dedicated nosecone or fairing. What I ended up with was not a Eve re-entry vehicle but a long 2.5m stack with a 10m deflated heatshield on the nose.

Heatshields are the most heat protective parts and can withstand up to 3300K of temperatures.

The 10m inflatable heatshield on the other hand does better and can withstand up to 3500K temperatures.

In your case: Then there is the bowshock of the heatblast. Generally parts exposed x meters behind the inflatable heatshield will be heatblasted. Other parts can also increase bow shock like upside down vector engines behind the heatshield...
Because the cross section of the vectors is behind the heatshield it's still protected from overheating.
By all luck the bowshock is such that it overcompasses the wider stacks behind the heatshield.

Sometimes the bowshock gets around, but, if you place a ablative heatshield in between the tanks where the bowshock ends the fuel tanks x meters below the heatshield will also be protected. Remember that you can empty the ablator in which case the heatshield weighs next to nothing. The reason parts below a ablative heatshield within a stack are protected is likely because of the white checkerboard shroud around a heatshield when it's attached within a stack.

Ultimately I ended up with a long 2.5m rocket with 1 LV-N at the back.

Result: I could punch into Eve's atmosphere as low as 50-52km at usual encounter velocities from a hohmann transfer trajectory from Kerbin. Normally a unprotected vessel would rip itself apart several hundred meters below 90km.

I see use for it, in your case it protects the re-entry vessel without requiring to inflate the shield. As a consequence you can inflate later to re-orientate the vessel for landing.
Another use I saw is that because I could use this setup to get deep into a atmosphere I could do more aggressive gravity assists by punching lower into an atmosphere.

A 90km periapsis Eve gravity assist or a 55km periapsis Eve gravity assist. The drag losses are negligble and especially when doing plane changes for destinations such as moho a 55km periapsis eve gravity assist can really achieve a Dv payback.

Edited February 22, 2019 by Aeroboi

[Aegolius13]

Interesting idea.  My experience has been that if your ship is too pointy, you won't slow down enough by the time you hit the really thick atmosphere, and things will get crazy hot.  But doing this, with an inflated heat shield at the BACK of the ship, could be a great way to maintain stability. 

Of course, there's also the issue of covering up all the stuff in front.  And since an uninflated heat shield only covers a 2.5m cross -section, if you never inflate it, you might be better off with the regular 2.5 heat shield.  I imagine it's draggier, plus it can probably dissipate more heat through ablation.

[Reinhart Mk.1]

wow did i actually discover something new or is it just a random effect being that my ship is so pointy and heavy?

[TheTripleAce3]

It does still protect you, look at @Stratzenblitz75 and his videos on land speed records and you'll see he uses them quite nicely with a rotated ablative shield too.

 

That might be fairing though, not quite sure.