ajburges

Actually, you want to light rockets when you lose speed. Aerobic engines have thrust multipliers in two curves: velocity and altitude. There is a speed were jets hit peak thrust (1000 m/s for turbos, 1300 m/s) the longer you linger there on jet power, the more thrust you get from your hyper efficient engines, and the less dV you expend to orbit. Going faster than this while your engines run wastes rocket fuel. As far as parabolic arc, good space plane ascent transfers from aerodynamic flight to ballistic trajectory as max speed is reached (and the lift surfaces can efficiently alter trajectory). For a mass optimal craft, you actually want to enter a gravity turn where you circularize between 50-60 km and the rest of orbital insertion is a Hohmann transfer. This minimizes the thrust of your orbital insertion burn and this OMS/ascent rocket mass. My goal is to have prograde at least 20° above horizon when I light my rockets.

A slower landing can actually be a detriment. A slope means you are landing off vertical. Even just 6 degrees of slope means you have 10% horizontal thrust. Worse, that thrust takes you away from the ground. A better bet is to hover a meter above land, then touch down with .4-.7 TWR and stability SAS. The minimal thrust will relax thrust cutoff timing requirements and a hover before touchdown reduces the forces that make landing on a slope hard. This method does waste fuel though. Your often better avoiding slopes period.

I'm hoping that 25 degree thrust offset (and a boom of 5 Modular Girder Segment XLs to the mining pod) is enough to avoid that issue. That angle still allows 90% thrust efficiency. I can't find hard data for E class radius though. The reason I'm even limiting myself to 900 kN is that I prefer the aesthetics of the 16 nuke array. Pushing that to 24 would require the use of the top and bottom of the Mk3 body and push part count of this design to dangerous levels. Plus, I'm as of yet unsure if just 2 small thermal control systems will be enough to manage the heat for 16 nukes attached to low thermal mass parts.

Anyone have any observations on the max force you can pull a claw with before you encounter more problems than normal? I'm designing an asteroid puller and would like to know if the almost 900 kN of engine thrust I'm giving it will be an issue.

If most of your lifting surfaces have the same incidence you should have a craft that's just as predictable. Be careful of Mk2 fuselages though. Lift surfaces only generate lift force if they have an AoA to prograde. Wing incidence increases AoA which increases lift. However, since it has a greater AoA than other surfaces, it will also stall earlier. Furthermore, since it has a different AoA than other surfaces, CoL will migrate depending on craft AoA! In fact, migrating CoL is one way to visualize how control surfaces give control authority.

For atmospheric flight, dV is a horrible indicator of range. The lower and/or faster your flight profile, the more dV you lose to drag a second. I only use it to ballpark SSTO performance since that follows a standard flight profile. To judge plane performance, map out the fuel expenditure of different flight modes. Learn how much fuel is needed to reach cruise speed and altitude, the average fuel economy of cruise, and the fuel (if any), needed for landing. Given the reduced size, mass, and pressure of Laythe you should need less plane than Kerbin. Still Kerbin circumnavigators are relatively easy to build if you know planes and they only take little more than a hour of game time to go around. A little planning and you can fly most of that at 4x time.

Indeed. You need a touch over 4 fuel cell arrays to power 3 drills and an ISRU at full bore. The number of drills needed to supply a ISRU fully will vary with with ore percent, but the mass does not scale well.

Check your profiles. If they overheat on ascent, you are spending to long to low. Check your ascent path. You want to hit max airspeed then use aerodynamic flight to start a climb to initiate a gravity turn to orbit. If you go beyond max thrust speed, climb faster. If they overheat on reentry, you are coming in too steep. I have yet to see any orbit with a Pe of 45 km leave the atmosphere again. That is your baseline reentry profile. You never use a intersecting trajectory to reenter atmospheric worlds. That is a waste of fuel and won't even buy you much time. RCS blocks hit 70% of critical temperature on reentry for me. That isn't even concerning. Only worry when the heat bar is red (85% of critical temperature)

Good point. Combining roles does reduce operational complexity. Mining operations get fuel for free so drill baby drill! I had some unstated assumptions: > You would keep the lander easy to fly (massive would realise some efficiency gains on its own from reduced overhead, better tanks, and more efficient, larger engines) > You had the piloting skill to consistently land the tanker within a klick of your minner. You need to be somewhat acetate to hit the good site anyway. Particulars of your operation may be defined by resource distribution. My survey results came back that the optimal Minmus resource node was in a flat that needs at least 9° of inclination to fly over. An optimal launch window every 11 hours does not sound good for on demand refueling though. I can place a fuel refinery that can be rendezvoused with as normal for refueling and run Ore to that periodically. I understand that the flats make for a good spot to rocket rover so I am toying with the thought of giving my tankers landing wheels and driving to optimally placed mine heads upon landing. Using fuel cells on mine heads is a no brainer to avoid concerns about visiting the site during the night.

If you follow optimal transfer, it's not much worse than Minmus return. Hint: aerobrake velocity is approximately ejection velocity (without braking manuvers). By the same token, Duna aerocapture is also pretty safe.

That's the catch. Lifter rockets run at circa 300 s. Getting ½-ⅆyour orbital acceleration with 3000 s engines will always win. OTOH, the margins get much tighter when you can only leverage that efficiency for ⅛ of your orbital acceleration and need to lug that extra mass for the remainder. Still SSTO is of dubious benefit in general once you leave the fun size system. Imagine where our space exploration would be if we could make the Blackbird an SSTO with a few JATO rockets! Isp: > The SABER engine peaks at 3500 s and goes to Mach 5.5! > RR Olympus (Concorde) peaks at 3000 s and reaches Mach 2 > P&W J58 (SR-71) peaks a 1800 s and hits Mach 2. The RAPIERS seem more "realistically" modeled than some other engines. However, a nerf to Whiplashes would make them as obsolete as Whesleys.

Crikey, I thought a take-off jet TWR of .6 was slightly over powered! Once you break 450 m/s air breathers give plenty of thrust. All my designs use discrete high efficiency vacuum engine arrays, so I also use them for the double duty of punching the sound barrier. High TWR designs do need less dV in all cases. Problem is that your average fuel per dV goes up due to the extra engine mass (and the tyranny of the rocket equation). Because of this, the most efficient vehicle is often the one with the lowest TWR that can still do the job.

[stupid mobile view deleting my posts then detecting false duplicates] The major fuel expenditure is the lander. That determines your efficiency. Ruthlessly cut the mass from it. I am convinced that the mass optimal transport for a mining system is the following: >Ore lifter with dV for just ascent (minner and station refuel it for every leg) and choice of landing gear. (Large ore tanks have best dry ratio of all tanks) > Orbital refiniery (bonus: can refine on just panels or RTG without penalty) > Mobile minner with ISRU, fuel cells, and horizontal claw/docking port. Either have enough tanks to mine a full load at optimal site before lander rendevous or mine at landing site.

BTW: torque per tonne is much less useful than torque per moment of inertia. That is angular acceleration. It is truly a personal preference. Folks have different tolerances. Too little and turns take too long and can be overpowered by engine torque. For example: my heavy space plane lifter takes over 10 seconds to turn 90° without thrust. Worse, I need to do the manuver without SAS as it can't correctly make the turn. The feedback mechanism does not consider angular momentum! That lack of consideration also means SAS can't control a ship with too much torque. For ships with a higher moment of inertia, you may want to use reaction wheels as a damper and rely on RCS for attitude control. Large ships tend to wobble. Having enough reaction wheel torque to turn them quick trends to induce oscelations.

Bleh! That far away, I am still progressing based on orbital period. Though KAC doe make it trivial to adjust course. Just accelerate along prograde until the closest encounter distance stops shrinking. Then correct inclination and wait a quarter orbit to intercept to fine tune further. I can always get and encounter within 10 m of my target this way. KAC also makes multiple orbit phase changes more accurate to.

Not that I'm against a Weasley buff, but most VTOL craft in real life use thrust vectoring. What we really need is either a "thrust vectoring" engine that steals thrust from other jets or specialized radial mount VTOL jets that have huge TWR but flame out before Mach 1. While several jets have greater than unity TWR, few exceed a ratio of 1.15 for the range of a continent and very little payload. Contrast that to the thrust monsters you can make in game.

Pedantic: gliders want CoL and CoM to be the same point. Using control surfaces creates drag. You want to maintain a glide slope without control surface use to maximise range. In fact, if you can't align, you want CoL ahead of CoM so your tail plane is creating upwards force to maintain positive AoA. After I finish reentry, I redistribute fuel so my pitch plane needs no trim to maintain course.

Soon the cult of the RNG will have numbers near the cult of the Kraken. Very soon...

A drill and an ISRU can be run at full capacity (with change) for just 3 fuel cell arrays. 4 arrays can almost power 3 drills and that ISRU at full bore. Solar Panels are for bootstrapping you contraption and mining Asteroids. Use fuel cells for everything else.

Also, the funds spent recovering them may outweigh the gains. Kickbacks should be a few hundred klicks downrange from KSC. We're talking 80% recovery. The break even point is 4000 credits for recovery equipment; any more, and you lose money from recovery! You also need to further reduce that number as adding recovery features will reduce lifter mass efficiency meaning you need more fuel. Just let the SRBs go. Focus on recovering the core of your lifter. My rocket fleet has no SSTOs, but plenty of 2STOs SRBs for launch TWR then the core does the rest and returns to KSC.

Map mode does not represent planet rotation. I see massive divergence of body fixed trajectory even on Mun and Minmus. If you are doing target ladings, overdo the thrust but plan to land on â…†throttle. Having buffer allows corrections.

I am waiting on the 1.25 m core to unlock, but my plan for an asteroid capture system is such: > 1 mine head: Drills, ISRU, solar, battery, claw, and a docking port sr. Nothing else. > 4 control nodes: claw, large reaction, wheel, probe core, battery, solar, RCS, normal docking port. > Power plant. 4 Nukes, 1 cabin (for engineer), 1 LF tank (limited to one to work around ISRU bug), port to attach to mine head, and ports to store confirm nodes. Absolutely no control authority. The control nodes are solely responsible for attitude, the tug is just a "dumb" thruster limited only by alignment. As a bonus, on delivery the tug detaches to be replaced with the remaining modules of a base! The rest of the modules are needed regardless.

Possibilities: Align the ports for massive craft along the normal Axis. This allows you an approach that is clear of obstruction and you can use ascending/descending nodes to plot arrival (you want intercept between the two at near 0 inclination) Once you rendezvous, don't dock. instead use RCS to establish a circular orbit of matching period to your station. Since you have the same period, your craft will proceed to dance around each other without much change is distance. Since the don't rotate in orbit, your desired port will face you within an orbit! Create an RCS tug (or pair) to properly manhandle you tanker into position.

if you want a dynamically unstable craft you want CoL ahead of CoM. Problem is you can't control such a craft without a fly by wire system (and significant control authority). Stock SAS is woefully insufficient as a flight control system for such craft. Control surfaces use a different AoA from the wing to create torque. You get control authority when that torque overcomes the torque of the CoL (whose strength is based upon the moment of inertia, the lift coefficient and the distance between the centers). In an aerodynamically stable craft (CoL behind CoM), that torque resists deviation from prograde with negative feedback. In a dynamically unstable craft, that force deviates from prograde with positive feedback. Need some info to help with repulsors. Are they modeled as a thruster or are they negative mass in operation. Still you want those to do most the lifting, so put control surfaces in the back for stability and forget about it. (or skip aero surfaces and use reaction wheels alone for control authority)

Ya, the Weesley was really hit hard by the Nerf Bat. Even ASL it has the same TWR as a RAPIER and 2/3 that of a Whiplash. Still, its the only jet engine that can be occluded by a Mk2 bay. Drag is king in the jet realm. If you can't occlude the jet, there is not much point to using high thrust power plants. The drag will really kill any performance. There are a few extra concerns for VTOL design: > CoM, CoL, and CoM become a maddening dance. - You need CoL set for traditional stability - You want CoM to be within a hairs breadth of VTOL CoL at all flight stages. - Jet's offset mass will throw your CoM way high! Mount the wings high for added stability and consider offset/rotated main engine mounting to reduce low fuel engine torque > You will want some hefty reaction wheels for VTOL attitude control. A few centimeters of CoL to CoT misalignment can create tens of kNm of torque! > You will want more pitch control than normal to fight engine torque in flight mode. Even when you do those. Adding VTOL systems creates a huge mass penalty that is proportionate to craft mass. Getting global (or better) range is tough. Mk2 becomes unwieldy at the needed sizes. I've resolved that a carrier jet is the more sane solution. I am waiting on scientist and engineer return to test a Mk3 mining jet with a reuseable rover. Should be able to land at a safe site and refuel as the rover fetches the survey sites. The rover has VTOL rockets to allow it to re-dock with the jet (as an added plus, it can sip up to half its fuel with a fuel cell to save battery weight). Heck, the on site refinement should remove the need to return to KSC after a survey. If you want to stick to VTOL craft. I recommend a STOVL (Short Takeoff Vertical Landing) or a pure STOL. If you only have the power to hover (1.1-1.2 TWR) at half fuel, you drastically reduce the VTOL engine requirements. Wings still give a surprising amount of lift at post stall speeds, they just need some help to prevent gravity from progressing the stall. You can also make your jet into a paraglider for much less mass. Being limited to 10-20 m/s at full throttle makes precision landing easier as well.