Aegolius13 Posted July 13, 2019 Share Posted July 13, 2019 With the BG hinges, it seems like now we can emulate the function of the AIRBRAKES with basically any part, which means the potential for bigger sizes and much better heat resistance. On the other hand, since robotics tend to be a bit floppy in the best of times, the extreme aero forces could do some odd things. I got to thinking about what parts might work well, and was wondering if anyone else has experimented with this, and what the results were in terms of effectiveness and survivability. Untested thoughts: Heat shields - obviously very high temperature tolerance, not all that heavy when emptied of ablator, cheap. But still quite a bit heavier than an AIRBRAKE. The regular ones seem like a better fit than the inflatables, since the latter are still bulky when retracted. Wing pieces - cheap, could generate lift while retracted if designed correctly, BigS parts can store liquid fuel. Structural panels - dirt cheap, excellent crash tolerance (there may be potential for some kind of combination aero surface / landing gear as in one of the Starship designs). Engine plates - pretty light for their size, excellent heat tolerance. Increasing the node count might increase drag? Inflatable airlocks - excellent heat tolerance, retractable, can store extra Kerbals for a wild ride. Static radiators - very good heat tolerance, theoretically able to cool themselves and their parent part. But not terribly large. Quote Link to comment Share on other sites More sharing options...
Snark Posted July 15, 2019 Share Posted July 15, 2019 I've been playing with this, and it works great! On 7/13/2019 at 7:51 AM, Aegolius13 said: Heat shields - obviously very high temperature tolerance, not all that heavy when emptied of ablator, cheap. But still quite a bit heavier than an AIRBRAKE. The regular ones seem like a better fit than the inflatables, since the latter are still bulky when retracted. Here I am using it on a Duna probe: This is a life support resupply vessel (I'm using TAC-LS), and it needed to get to Duna in a hurry, so it arrives going around 6 km/s relative to Duna when it hits atmosphere. See those two rows of 1.25m heat shields protruding from the aft end? Robotics. Each of those arms is a G-00 square hinge (i.e. the little one) with a long row of cubic octagonal struts attached to it. The heat shields are mounted on the side, and protect the hinge and the cubic struts. When I launch the craft, those arms are folded down flat against the sides of the ship, and create fairly minimal air resistance. (The big 2.5m heat shield in front has a disposable nose cone atop it at launch.) When it hits atmosphere, those arms sticking out to the sides are great for adding drag. :-) I aerobrake at 6 km/s down to an altitude of 17 km or so. Max deceleration hits around 30G! And with those things trailing out behind, it is rock-solid aerodynamically stable with the big flat heat shield in front. To stop the hinges from bending under those tremendous strains, I set the outermost of the small heat shields to "autostrut: root part". After extending those side arms, I turn on the hinges' "lock" function, which allows the autostrut to go from the radial heat shield to the probe core at the center of the ship, holding the arms firmly in place. Another use of robotics in this picture: note that the solar panels are mounted on extended pistons. I've put both "toggle solar panel" and "toggle piston" into the same action group, so it's one key press to both retract the panels themselves and pull them in snug against the body of the craft, so that they're protected by the heat shield. On 7/13/2019 at 7:51 AM, Aegolius13 said: Wing pieces - cheap, could generate lift while retracted if designed correctly, BigS parts can store liquid fuel. These make great airbrakes for rockets. I mount them so that they're folded down flat against the sides of the craft at launch (similar to what I've done with the heat shields in the above example), then I spread them as shown above for reentry. Works fantastic, generates tons of drag. (Though limited in temperature tolerance, compared with heat shields, of course-- so no 6 km/s reentries that way!) Again, though, need to use hinge locking to hold them stiff, otherwise the motors in the hinges aren't strong enough to keep them forced open against the incoming airflow. I've also had good luck using helicopter blades from 1.7.3. Here's a super compact and cheap LKO rescue vehicle: Does a powered landing on a Spark, no parachutes involved. Works great. Quote Link to comment Share on other sites More sharing options...
Aegolius13 Posted July 16, 2019 Author Share Posted July 16, 2019 On 7/14/2019 at 6:25 PM, Snark said: Does a powered landing on a Spark, no parachutes involved. Works great. Does it spin? I hope it spins. Quote Link to comment Share on other sites More sharing options...
Snark Posted July 16, 2019 Share Posted July 16, 2019 1 hour ago, Aegolius13 said: Does it spin? I hope it spins. Considered it, but rotational stability can be tricky. In particular, it's not gonna spin unless I turn off SAS, and then it has to be dynamically stable while spinning, which is tricky. So I just have the blades flat-on against the airflow, no spinning. At some point I may try an autorotating lander, but haven't had the gumption yet to tinker enough to make one work. Quote Link to comment Share on other sites More sharing options...
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