Low-Bypass Solid Boosters For Reusable First Stage

I had previously wrote about my idea to have bypass canals around the solid boosters too improve on the specific impulse. (Low-Bypass Solid Rocket Booster) The idea can be combined with the modular rocket design I had proposed. (Modular Hybrid Reusable Rocket) The solid boosters of the first stage can have the bypass canals around them. The first stage of the rocket would climb up to 70km altitude and that is where the atmosphere would contribute positive to the thrust of the boosters. In later stages this approach would not work. The solid boosters slick design improves on the feasibility compared to liquid rockets. Different bypass ratios can be tested for optimal efficiency. The larger diameter of the first stage due to bypass canals may or may not positively help the descent of the reusable first stage. It has to be taken into consideration as well.