realseek

You are amazing! Thank you for making this badge, I love it

Here is my solution to this SSTO challange - it was difficult... Enjoy!

Thank you, Kergarin for the kind words and compliments! It all started for me when a friend gifted BG to me because I did not want buy it initially... it made my stock propeller designs from before seem like toys My first attempt in related crafts were a staged Eve lander, which used propellers for pure vertical ascend, and a Kerbin SSTO with rotating ducted propellers for VTOL. I learned a lot from those. To answer your questions: There are 16x R25 blades on each EM-64S motor. The motor is set to 60% power and a max RPM of 400. Testing at 16km on Eve showed that this rpm produced the most thrust, for some reason... The whole motor assembly is placed once in the front and back to help with weight distribution and aerodynamic stability. In total, this is 7 tons of dead weight for the electric stage. Sounds like a lot, but in the end its only 12% of the dry mass... Aerodynamics optimization and TWR become the most important part once you ignite the rocket engines. Ideally you fly prograde most of the time and let the wings lift the craft out of the atmosphere while gaining decent horizontal speed. For me, the best wing incidence was at 3.5 deg. If your initial TWR is too low, then much fuel is wasted just breaking the sound barrier and climbing above 20km where the air gets thinner. Too high TWR might cause yout to accelerate quickly in the thick atmosphere just to throttle down later, or carry to much engine weight. I have tried a single engine type before, but could not reach enough dV -- diminishing returns due to high dry weight -- without beeing too heavy to fly up to a decent altitude on electric power. In the end, it is very tricky... It is possible to end up in a "local maxima" of a design without reaching orbit yet, where the only way to make it any better is to make big breaking changes. Best of luck with your Eve SSTO attempts! Here is a gallery of my SSTO that shows some more details: https://imgur.com/gallery/afVyAv1 I will upload a craft file later, once I had time to do a complete mission.

I love finding these "impossible" challanges here in the forum. Trying to proof somebody wrong is a fine motivation, don't take that away from us, EvermoreAlpaca Anyhow, this one is actually possible! If anybody is still interested in the solution I could upload a video. The trick is to design for very high L/D at 20km and bounce of the atmosphere multile times while accelerating to orbital speed... Easier said than done

Thanks! This post was very helpful and a big inspiration. I was already playing around with stock propellers before, but seeing what @EvermoreAlpaca had to go through with his Eve propeller design made me quit... Since Breaking Ground this became viable again because electric motors are so much lighter than dozens of reaction wheels.

After weeks of tuning and design work, I humbly submit my own creation in this topic: A Single Stage To Orbit that can take off from Eve at sea level. This is made possible by using propellers from Breaking Ground to first climb out of the thick atmosphere. The SSTO is fully functional, contains ISRU, seats for two Kerbals, science equipment and two LV-Ns for interplanetary travel. It can land fully fuelled and has infinite range inside Eve's atmosphere. No modded parts, clipping or aerodynamic trickery was used. Leaving a small amount of LF in orbit around Eve and refuelling on the surface, it should be possible to do a full round trip from Kerbin to Eve's oceans and back. Hope you will find this interesting, as this is the first time I made a video to share! https://www.youtube.com/watch?v=FSzZ4CYb0LE