[Issues with Kerbalized SpaceX]

On 7/27/2018 at 3:48 AM, infinite_monkey said:

You might want to try Tundra Exploration

Does it not have the Kerbalized SpaceX dependency?

[KER Suicide Burn Readouts]

On 7/27/2018 at 9:53 PM, HebaruSan said:

If you're interested, there are some details about how and why these numbers are faulty here:

 

Thanks a lot for directing me to this post. It answers many questions I had of the readouts, and how to interpret them. I'll be on the lookout for future updates and in the meantime, use my haphazard way of doing the suicide burns. 

Been trying a few Falcon booster landings without kOS, and it's real tough. 

[KER Suicide Burn Readouts]

I consider KER a very essential add-on to the game. However, I do encounter the occasional frustration while using it.

Specifically, the suicide burn functionality. In the readouts, I have suicide altitude, distance and dV all showing in my surface tab. I use the suicide burn distance to judge when I begin my suicide burn, am I right in doing that? In atmospheric landing, the velocity cancels out much quicker than my reaching the ground (usually cancels at around 500m). And for non-atmospheric landings, the suicide burn distance goes into the negative although I've started my retro-burn, causing me to crash (very frustrating)

I resort to you kerbonauts for help, since I would love to get a handle on the suicide burns. Right now, I just have the vessel acceleration readout, and I get the maneuver burn time readout. Creating a maneuver node at the approximate landing spot to cancel velocity, I know how much dV I'll approximately need. The 'Time to Surface' readout gives me a baseline for when to begin my retro burn, giving between 5 and 7 seconds delay between the 'maneuver burn time' and the 'time to surface' depending on the engines I have aboard to get close to doing one perfectly.

 

[Issues with Kerbalized SpaceX]

Okay, so I've been using Kerbalized SpaceX, Kerbal reusability expansion and FMRS to simulate some Falcon 9, Falcon Heavy and BFR launches. My first issue has to do with visuals, the second is about the deltaV readings, and the other is just a peeve that bothers me.

1. When using any of the parts with inbuilt, or placed RCS thrusters from the mod, (SuperDraco RCS, the Dragon capsules, BFR tank), the RCS exhaust is far too large and bright, and also points in the wrong direction. Has anyone else encountered this problem and have they solved it?
2. The delta V readings (KER) I get from using the SuperDraco engines from the mod are erroneous. They show a much higher value than should be if following the rocket equation, and I experienced the readings from KER show 2800 m/s in space, and with a 700 m/s manuever, the total readout dropped to around 500m/s
3. The mass of engines: specifically the Merlin Cluster, and the BFR engines. The mass of the Merlin cluster is 4.0 t (equivalent mass of 9x IRL Merlin 1D engines) , and provides around 9000kN of thrust, which sounds like a ridiculously high TWR for the engine. However, the most powerful stock engine, the Mammoth (15.0 t and 4000kN of thrust). Meanwhile, the Merlin vacuum engine in-game weighs 6.5t for 1000kN of thrust. I just want to know the proper mass of the engines so I don't feel like I'm cheating the game.

 

[Interplanetary Gravity Assist Tutorial]

Hey. Novice kerbonaut here.

I've been meaning to try my hand at efficient interplanetary travel for a while, and look on in awe as people continue to post their crazy trajectories to Eeloo and others.

So I'm looking to practice interplanetary gravity assists , to get a better instinctive feel for planning future missions. Can anyone post some flight paths that would enable me to learn? For example: A braking gravity assist at Duna to get to Eve OR using an Eve gravity assist to change inclination to match Dres or Jool to drop back down to Duna. A series that would acclimate me to understanding what assist I should use to get where i want. 

Right now, I have a basic idea of how gravity assists work, but know nothing about planning them for efficient transfers.

Any help is appreciated.

P.S. I know this is a tall order, and my phrasing of the question may not be entirely accurate. In which case I'd be glad to clarify what I mean.

[Does an Asteroid's class change if you mine it]

26 minutes ago, bewing said:

No. The class is more determined by the physical size of the asteroid, and that doesn't change when you mine it. It'll still be class E, even when it's hollow.

Thanks a lot @bewing. Look forward to your other posts ☺

[Does an Asteroid's class change if you mine it]

Hey. Novice kerbonaut here.

I took on a contract that required me to capture a class E asteroid around Minmus. Many brave kerbonauts have tried and failed. (6 to be exact, 2 died whilst performing an aero braking maneuver, far too early along the tech tree) in trying to maneuver a 1900 ton monster of a rock which could be used as an orbital refinery. 

At this point I'm a year away from failing the contract, and the encounter occurs in 200days. I figured I'd mine the ore out of it and capture into Minmus. But the question remains. If I mine an asteroid to its empty mass, does that change its class? 

Any answers are welcome

 

[Space plane design help]

Thanks for the reply. 

9 hours ago, Ohm is Futile said:

...but as much as overdoing #5 may compromise #1, not following tip #5 may compromise #3, which is why the only SSTOs I bother with tend to be rockets and not planes.

Yes, #3 has to be followed. The majority of my spaceplanes are cargo lifters to a station at 200Km LKO. I've poured hours into honing my Mk2 spaceplanes for tiny probe launches and I had to move into Mk3 to avoid the cargo from getting stuck in the cargo bay. I've designed one Mk3 spaceplane that way, and it works, the only issue I face is the constant fight i put up with sas to keep the nose steady and pumping fuel around to maintain control. (Not a huge problem, but I like simplicity). 

And on another note, I haven't yet built my first rocket SSTO. I also believe those would be much simpler than spaceplanes, only that I haven't yet worked out the math yet. I do have one returnable rocket, carries an orange tank and a half to the same station. Only expenses are on 6 Kickbacks and fuel.

9 hours ago, Ohm is Futile said:

That said, #5 shouldn't be that hard, you only really need to make sure your fuel tanks are either already centered on the CoM or that you spread the mass around your plane equally. It does get harder when you need a bunch of heavy engines at the back, though...

Yes, that would be the ideal solution, but cargo bays make that a problem. One solution was using ballast equivalent to the dry mass of each half of a spaceplane, which as you go bigger becomes a huge problem on the engines. I keep my spaceplanes from 0.65 to 0.75 TWR to try and maximize payload fraction. And I tend to use only Rapiers and a Ramjet or two for large vehicles. NERVs are for celestial travel only.

9 hours ago, Ohm is Futile said:

...but there's a limit on how big your plane can get if you don't build radially, otherwise you will get spaghetti just like any rockets... or rapid unscheduled disassembly due to drag and G-Forces tearing your plane apart the moment you touch the controls (or your CoM moves too much due to burnt fuel).

#4 is so simple yet so smart, I might have to try building spaceplanes again... can't believe I didn't think of that.

Thanks for that tip. I haven't built quite that large yet, like Matt Lowne's Argus class spaceplane. I'm starting to prepare my fleet of Duna and back spaceplanes myself. But I expect building radially will become a neccessity soon.

You may thank GoSlash27 for #4, helped me loads. I've actually studied aerodynamics and a fair amount of aeronautical engineering but didn't think to apply it *facepalm*

I happen to draw a lot of inspiration from KSP tubers like Mark Thrimm and Matt Lowne. My whole tryst into spaceplanes was merely due to the long drawn out waiting times between maneuvers of craft waiting for ejection or on interplanetary trajectories. 

[Space plane design help]

Hi, novice kerbonaut here.

I've successfully designed and created multiple SSTOs of all classes that are Mun and Minus capable, thanks to many of the topics here and KSP tubers. 

Some important tips are:

1. Low drag is better than high thrust (Thank you GoSlash27 and Warzouz)

2. Control surface placement is key (Thanks to physics)

3. Centre of mass ahead of centre of lift (Just try and see what happens if not)

4. Static incidence in wings, i.e. tilt your wings to include a little angle of attack while level so that thrust in prograde can still generate positive climb without control surface drag losses.(GoSlash27 at God level IMO)

5. Try to ensure dry center of mass remains within 5% deviation from its initial position (preferably at the center for maximum aerodynamic control authority)

Tip number 5 is where I struggle with. I try optimising my vehicles by messing around with fuel placement, but can never seem to keep track centre of mass within those limits. (Sorry, will not be attaching craft files just yet).

Most of the time, this shift is unavoidable until I use radially placed fuel tanks and engines, which comes into direct contradiction of tip 1, and tip 1 always gets more preference for efficiency purposes.

So to conclude, I'm asking for tips about how my designs can incorporate that last shred of increased efficiency through smooth control.