Modular Expendable Launch Vehicle (MELV) Family

[sturmstiger]

I'd like to share my ELV designs, which was created with the following goals:

1.Simple: a few parts as possible. The heaviest variant which lifts 100 tons to LKO has only 57 parts.

2.Modular: use only a few common stages to build a versatile family of launchers. The common stages allows (in RL) reduced per-unit R&D and manufacturing cost.

3.Reliable: by minizing part count and staging events. They are also very stable to fly, and require no additonal struts from most payloads.

4:Realistic: the ELVs should look and perform not too different from real world ELVs.

The result is a family of light, medium and heavy ELV configurations covering LKO capabilities from 3 tons to 100 tons, built from 4 common stages:

1. Medium Liquid Booster (MLB): 2.5m core and (in heavy configurations) strap-on boosters. Using a single 1300KN, hydrocarbon, ground-start engine. Crossfeed capable. 3 parts and 86 tons. This can be duplicated with 2x36ton tank + 1x18ton tank + main-sail for a stock-only stage with similar performance.

2. Light Liquid Booster (LLB): 1.25m core and (in medium configurations) strap-on booster. Using a single 230KN, hydrocarbon, ground-start engine. 3 parts and 11.5 tons.

3. Medium Upper Stage (MUS): 2.5m upper stage for medium lift configurations. Using 2x120KN hydrolox engines. 6 parts and 11.3 tons.

4. Light Upper Stage (LUS): 12.5m upper stage for the small launch vehicle. Using one 120KN hydrolox engine. 2 parts and 5.6 tons.

The configurations are labled similar to some real life ELV (Delta IV / Atlas V) naming systems: CMLU-T, where C = class, M = #MLBs, L = #LLBs, U = #upper stage engines, T = capability to 75ton circular orbit. For example, M142-25 means a medium lift vehicle with 1 x MLB core, 4 x LLB strap-on boosters and 2 x upperstage engines that lifts 25tons to LKO. The max payload mass came from Mechjeb autopilot ascent tests using the same ascent profile: start turn at 10km, end at 50km, turn shape 50%, end turn angle 5 deg, auto-throttling, auto-staging with 0.5sec staging delay. No need to disable gimbal if use Mechjeb or is reasonably at flying rockets. 1~4 ton margins, proportional to the lift capacity, were substracted from the max payload rating (for piloting errors, payload fairing weight, etc), e.g., H700-100 were tested to lift 104+ tons to orbit, and M102-15 can lift 16+ tons. The part count & LV mass given belows does not include payload fairing or launch clamps.

The heavy lift variants are simply 7, 5 and 3 MLBs strapped together with fuel cross-feeding. Below are my main lineup, including the L011 light launch vehicle, the M102, M122 and M142 medium launch vehicles and the H300, H500 and H700 heavy launch vehicles. Other configurations may be used when there're special needs, including the M140 (M142 without the upperstage rocket for launching all my Duna outpost missions), L011+ (L011 strapped with 2 small solids for Trinity mun missions) and M101 (low cost launcher for robotic interplanetary missions).

H700-100 : 100+ tons to orbit. 57 parts, 3 stage, 603 ton.

H500-74 : 74+ tons to orbit. 39 parts, 3 stage, 430 ton.

H300-42 : 42+ tons to orbit. 19 parts, 2 stage, 258 ton.

M142-25 : 25+ tons to orbit. 36 parts, 3 stage, 145 ton.

M122-20 : 20+ tons to orbit. 24 parts, 3 stage, 122 ton.

M102-15 : 15+ tons to orbit. 12 parts, 2 stage, 98 ton.

L011-3 : 3.5 tons to orbit. 6 parts, 2 stage, 17.35 ton.

Subassembly craft files:

Can be opened directly on 0.20+. Best used as subassembly with Subassembly Loader or Subassembly Manager.

https://www.dropbox.com/s/i5yfzi28nfptos9/MELV-H700.craft

https://www.dropbox.com/s/jzqdglnvleh9ndl/MELV-H500.craft

https://www.dropbox.com/s/xbib4n0j0rxwj5b/MELV-H300.craft

https://www.dropbox.com/s/bypqq4d2i7etc5y/MELV-M142X.craft

https://www.dropbox.com/s/ikdlc711sbwj6km/MELV-M122X.craft

https://www.dropbox.com/s/n03z7f3ju2z7tn7/MELV-M102X.craft

https://www.dropbox.com/s/yk40i0mv9gk7b5q/MELV-L011.craft

Edited July 23, 2013 by sturmstiger

[sturmstiger]

And here are the stock-only versions of the heavy ELVs. They are pictured with interplanetary tugs as payloads.

SR500-76: 76+ tons to orbit

SR300-42: 42+ tons to orbit.

For new players, this shows how to build fairly powerful and very reliable rockets with very few parts. For example, SR500-75 consists of 35 parts:

5x Medium Liquid Boosters, each built from 1 full-sail engine, 2 orange tanks and 1 18-ton tank, vertically stacked.

4x TT-70 Radial Decouplers, attaching the 4 strap-on MLBs to the core. Attaching at the upper orange tanks reduces the weight load on the lower tanks.

4x struts from strap-on booster to the core at the 18-ton tanks, and another 4x struts from lower orange tanks to the core's upper orange tank. For long or fat payload add a set of struts from the payload to the strap-on boosters, to prevent payload from wobbling.

4x sepratrons at the top of strap-on boosters, pointing at the core, fired during strap-on booster separation.

4x launch clamps holding the strap-on boosters, attached at the same height of the decouplers.

4x fuel lines from strap-on boosters to the core, for fuel crossfeeding (aka "asparagus staging"): all engines firing at liftoff, and strap-on booster separation once their fuel runs out. Another scheme of crossfeeding involves 2 boosters feeding the other 2, which in turn feed the core - this creates two booster separation events for a small increase in performance.

Craft files:

https://www.dropbox.com/s/9lnffrwxkwm96pt/SR2_42.craft

https://www.dropbox.com/s/o2p3ts5n7rsycwx/SR2_76.craft

Edited June 6, 2013 by sturmstiger

[sturmstiger]

SR700-100: 100 tons to orbit, 61 parts, 3 stage, 660 tons self-mass.

And here's the second stage of SR-700 with its dubiously useful 100 ton test payload. If it looks like SR-300 it's because SR-700 second stage is a SR-300.

Edited June 6, 2013 by sturmstiger

[pinolallo]

Nice work. I'm going to try that lifter for the 3MB

[wasmic]

Hmmm, nice, do you perchance have a rocket capable of lifting 205 tons into orbit? That's the weight of a full large spherical fuel tank with expanded ring.

[sturmstiger]

Hmmm, nice, do you perchance have a rocket capable of lifting 205 tons into orbit? That's the weight of a full large spherical fuel tank with expanded ring.

Unfortunately this family of ELVs currently does not have Super Heavy Lift configurations. Have you checked out PolecatEZ's Mammoth Rocket Family?