Launch optimal TWR

[Wobbly Av8r]

3 hours ago, CBase said:

Actually what is recovery friendly on Twin-Boar ? I would always consider a Main Sail engine with 2 Jumbo tanks and small control wings more recovery friendly as the performance across all altitudes is better. Personally I added fixed and recovered 1.25m tank and engines to scale performance until I unlocked bigger diameters.

Well, on a head-to-head comparison [ Okto2 probe + battery in 2.5m identical streamlined fairing, Large Advanced Reaction Wheel and an inert Jumbo-64 tank payload, the Twin-Boar vs. Mainsail+Jumbo-64 launched with Radial Out SAS ]

1. The cost for the Mainsail is ~10% more expensive out of the gate;
2. While the Mainsail wins the Isp comparison (285s - 310s) to Twin-Boar's (280s - 300s)...
3. ...the Mainsail produces less thrust (1,379 kN - 1,500 kN) than the 'Boar (1,867 kN  - 2,000 kN), which results in...
4. ...(when launched from KSC with identical payloads) the Mainsail lifts its payload to 73,000m while the 'Boar achieves 79,500m. (~9% higher)
5. The weight distribution/aerodynamics of the 'Boar allow reentry with natural stability, i.e. no airbrakes or such necessary for engine-first descent profile.
6. The entire tank/engine combo of the 'Boar has 20 m/s impact tolerance, the Mainsail combo 7 m/s on either; 2 parachutes (weight & cost) are all that's needed to recover even on land.

On a cost per kg basis, I think the 'Boar wins and the "easier" recovery (required equipment, impact tolerance) seal the deal for my space program which reuses the boosters I use to put my payloads in LKO. I've explored the drag profile of the 'Boar extensively, but not the Mainsail - the 'Boar is interesting in that it has high drag until Mach 1 and then reduces quickly - not sure how that plays into the comparison, but the head-to-head comparison still validates the overall performance of the 'Boar.

Let me know what you think...

Edited September 6, 2020 by Wobbly Av8r
Clarity