Yes that was exactly what I was doing - only lower periapsis enough to aerobreak into a very high Eve orbit. Sorry if it wasn't clear.
I thought I might include a previous craft of mine (craft B) to explain why I am puzzled at this latest one's performance (craft A). The craft is of similar design: fairings ahead and deployable airbrakes (made with wings facing the airstream attached to robotics hinges). It was a proven design so I was pretty confident before sending my kerbals to their destiny.
I sent both to Eve-Kerbin transfer at the same window (couples of hours apart to switch control), so entry profile should be very similar. I got craft B to an even lower aerocapture periapsis (75km) than craft A (77km). Here is craft B's performance:
- At 84km and 4628m/s (slightly higher than craft A), the fairing barely heats up: https://imgur.com/0CdJqlv
- At periapsis (75km) and 4552m/s (almost the same as craft A at 84km), the foremost fairing heats up significantly but nowhere even near maximum temperature like craft A at 84km: https://imgur.com/tQRqgBi
Craft B made a safe aerocapture to Eve. I am puzzled on why the thermal performance is so drastically different?
- Is it because craft B is composed of 3 fairings instead of one big one?
- Craft A is heavier (46 tons) compared to B (16 tons). But with similar entry speed and altitude, shouldn't atmospheric heating be the same? The majority of drags should occurs at the airbrakes (craft B only have 3 airbrakes, while craft A has 4, and each has larger break area to account for increased mass)
- I had previous design with heat shield before, and could get them to much lower aerocapture periapsis (60-70km) to get captured by Eve. From previous experience, without heatshield the fairings will overheat at periapsis of 71km or below. I experimented with the deployable airbrake design using robotics hinge because:
A/ it always allow aerocapture at 77k periapsis or above, well above the fairing tolerance range, so I don't need heat shield
B/ can be scaled up for higher vessel mass
C/ Much finer altitude control in the final circularizing aerobreak
That's why I can't understand how craft A's fairing heats up so rapidly to maximum temperature at 84k altitude - fairings were only in danger zone at 71km or below before, and heating happened slowly over the entire trip, not so rapidly in 3-4s like this.