Author Topic: Kerbal Space Program (Read 12344 times)

Molly · « **Reply #60 on:** April 17, 2014, 11:49:01 am »

visitors can't see pics , please register or login

Thomek · « **Reply #61 on:** April 17, 2014, 12:46:42 pm »

Whats funny is that not even the folks at NASA understood orbital mechanics properly in the 60's..

"First attempt failed[edit]
The first attempt at rendezvous was made on June 3, 1965, when US astronaut Jim McDivitt tried to maneuver his Gemini 4 craft to meet back up with its spent Titan II launch vehicle's upper stage. McDivitt was unable to get close enough to achieve station-keeping, due to depth-perception problems, and stage propellant venting which kept moving it around.[3] Mostly however, the Gemini 4 attempts at rendezvous were unsuccessful largely because NASA engineers had yet to learn the orbital mechanics involved in the process. Simply pointing the active vehicle's nose at the target and thrusting won't do. If the target is ahead in the orbit and the tracking vehicle increases speed, its altitude also increases, actually moving it away from the target. The higher altitude then decreases velocity, putting the tracker above and behind the target. The proper technique requires changing the tracking vehicle's orbit to allow the rendezvous target to either catch up or be caught up with, and then at the correct moment change to the same orbit as the target with no relative motion between the vehicles.[4]

As GPO engineer André Meyer later remarked, "There is a good explanation for what went wrong with rendezvous." The crew, like everyone else at MSC, "just didn't understand or reason out the orbital mechanics involved. As a result, we all got a whole lot smarter and really perfected rendezvous maneuvers, which Apollo now uses."

—[4]"

Kafein · « **Reply #62 on:** April 17, 2014, 05:50:12 pm »

In their defense, orbital physics are unintuitive, which is 90% of the fun in KSP.

Armpit_Sweat · « **Reply #63 on:** April 19, 2014, 03:47:17 pm »

visitors can't see pics , please register or login

(click to show/hide)

3 x Propeller Engines
3 x Jet Engines

Max crew: 1
Wet Mass: ~25.000
Liquid fuel: 1820
Cruising speed at low altitude: ~350 m/s
Cruising speed at 10km: ~600 m/s
Top speed at 20km: ~1300 m/s

(click to show/hide)

----------------------------------------------------------------
Mods used ( all compatible with latest patch 23.5 ):

Ferram Aerospace Research

Kerbal Aircraft Expansion

Procedural Wings

EDIT:

Sad news in Kerbin Space Center: Bill passed away in tragic accident during a flight-test of an ultralight single engine propeller aircraft.

visitors can't see pics , please register or login

visitors can't see pics , please register or login

22 G was few Gs too much for poor Bill...

Kafein · « **Reply #64 on:** April 21, 2014, 11:42:13 am »

I hope cleaning the interior afterwards wasn't too painful. Dying of 22G must have fabulous consequences.

BlindGuy · « **Reply #65 on:** April 28, 2014, 06:44:07 am »

I could totally work for NASA after I safely got Jeb Kerman to all the major planets and moons ( and back of course, that drop back to the surface is the nectar in this sweet game). Orbital link-ups? no problem! Docking even as we plummet together with the parent craft into a planet? No problem. Jeb safely rides the parachutes back to safety clutching samples from all over the solar system? NO problem! This was before the asteroids tbh, havent played in years. Jeb Kerman for president tho, he is a hero whose valour and confidence never even wavered.

Armpit_Sweat · « **Reply #66 on:** February 06, 2015, 06:13:06 am »

Have been grinding Temperature Measurement and Kerbin Exploration missions, so had to make an efficient aircraft capable of long distance flights to get EVA reports and surface samples, along with ability to climb 20km+ to get Crew reports.

Sounds easy enough, but using Ferram Aerospace Research mod makes larger aircrafts very unstable in thin atmosphere, and smaller planes burn fuel long before reaching their target.

After many attempts, various engine combinations and tedious balancing i have finally achieved my goal! This hybrid jet/rocket aircraft was capable of completing every mission of the two types mentioned above, has shown a remarkable flight stability even in a x4 speed mode, has a perfect balance of center of lift and RCS Torque against wet/dry mass, along with a simple and cheap construction.

It is somewhat sensitive to "maneuver-stress" in lower altitudes at high speeds, but it is to be expected of a craft with its weight and length ratios.

visitors can't see pics , please register or login

RCS Torque 0.002 kNm
Wet/Dry center of mass offset 0.05m

visitors can't see pics , please register or login

visitors can't see pics , please register or login

Rocket engine is used to rapidly climb to high altitudes, as a standard jet engine has way too little thrust. A plane of this size is unable to reliably use the lifting force of it's wings above ~15km, so stalling was always a risk even with minor control mistakes when i was using jet engines alone. RCS is needed for reliable maneuvers at peak altitudes.

visitors can't see pics , please register or login

Landing gear and wings are made of parts from Kerbal Aircraft Expansion, Jet engines taken from Karbonite mod, RCS thrusters are from RLA Stockalike mod, and the rest of the parts are stock.
I hate stock wing selection, they seem to have different textures and do not match well together... These jet engines have similar stats to stock jets, but can be mounted at 90' and save me some money, along with making the weight balancing easier. I like these custom RCS thrusters because they have fewer nozzles, and save me fuel by not expanding it in useless directions ( i only need them for pitch and roll control, so forward and backward nozzles would be wasting the gas ).

I have used a "struted" version for the missions, but it looks uglier

Thomek · « **Reply #67 on:** February 06, 2015, 03:43:45 pm »

Just installed FAR, but haven't tried it yet.

My best non-FAR ssto:

(click to show/hide)

Armpit_Sweat · « **Reply #68 on:** February 06, 2015, 09:01:20 pm »

Quote from: Thomek on February 06, 2015, 03:43:45 pm

Just installed FAR, but haven't tried it yet.

My best non-FAR ssto:

(click to show/hide)
visitors can't see pics , please register or login
(click to show/hide)
visitors can't see pics , please register or login
(click to show/hide)
visitors can't see pics , please register or login

Looks nice and clean!

Can you drop the ship's file, so i can test it with FAR and Deadly Re-entry?
I expect to burn through most of the fuel before even leaving the atmosphere... May be if i switch the cargo-hold with a fuel tank?..

Is it easy to land? TBH i have never made a successful FAR SSTO without using any staging

I am was only able to make a vertical launch and "normal" aircraft landing, while dropping the used rocket stage when reaching space.

Btw, do you have any other moded parts on it? Or only the "utilities" like that Air-intake balancer and K-Engineer?

EDIT:

THe cargohold is from a mod, right?..

Thomek · « **Reply #69 on:** February 06, 2015, 10:24:38 pm »

I managed to save over the successful version with a less successful (8 engine..)version..

The cargohold is in stock game!

I don't think I used any special mods for this. Ah yeah the nose cone is from a mod, I think "MK IV Spaceplane System". I like a challenge

Tested FAR today though.. uhm.. Harder

I don't think it would work with FAR.

But the design is simple:

* Place wings a little high so the engines come more in-line with center of thrust.
* Engine "unit" have just an aviation tank and a small rocket tank.
* Keep the main body as light as possible. No tanks on it.
* Do use a strut under each wing connected to the engine units! Their weight counteract a lot of wing bending, but need some support on the ground and extra stiffness.
* I try to have 1 lift per tonne.

I tried and tried and tried, to make a next one capable of carrying an orange tank (36t) to orbit, but it always fell apart. You'll need more thust (More engine units), much larger wing (to carry extra engines + cargo), and I just couldnt make it.

For stock, I think this is a fairly clean practical design. Didn't try to land it, but I landed one of the prototypes. It flies ok, but needs love at high altitudes and speeds.

Some numbers I figured out:

Try to have about 1 lift per tonne.
Each "Rapier Engine unit" can support around 10 tonnes of your total mass to orbit.

I'll try to play a bit with FAR now.. but I doubt it will be feasible. Perhaps less tonnage? We'll see.

Armpit_Sweat · « **Reply #70 on:** February 07, 2015, 12:25:18 am »

Quote from: Thomek on February 06, 2015, 10:24:38 pm

I managed to save over the successful version with a less successful (8 engine..)version..

It's a great shame, but i know your pain! Did it many times myself, so now i always make a new save after each successful test-launch.

Quote from: Thomek on February 06, 2015, 10:24:38 pm

* Place wings a little high so the engines come more in-line with center of thrust.
* Engine "unit" have just an aviation tank and a small rocket tank.
* Keep the main body as light as possible. No tanks on it.
* Do use a strut under each wing connected to the engine units! Their weight counteract a lot of wing bending, but need some support on the ground and extra stiffness.
* I try to have 1 lift per tonne.

Interesting. Hmm, what is the theory behind the light body/fuselage?..
I don't know anything about real-life aircrafts or even engineering in general, but ( my ) common sense suggests keeping all mass in front of the center of thrust. In other words i try too have all the weight as close to the center of my craft as possible, while having engines as far behind as possible. ( excluding landers, rovers and other specialized stuff )
The sum/vector of all the thrust is in the center anyways, or that is not how physics works?.. I honestly don't know. Just having a "gutfeeling" that heavy wings and light body will make it spin and shake at some point.

Quote from: Thomek on February 06, 2015, 10:24:38 pm

For stock, I think this is a fairly clean practical design. Didn't try to land it, but I landed one of the prototypes. It flies ok, but needs love at high altitudes and speeds.

Some numbers I figured out:

Try to have about 1 lift per tonne.
Each "Rapier Engine unit" can support around 10 tonnes of your total mass to orbit.

I'll try to play a bit with FAR now.. but I doubt it will be feasible. Perhaps less tonnage? We'll see.

I will try to make one now! Going to smoke a joint and dedicate the next 4-5 hours to this task. I will probably end up making a 100t 10 engine monster, and get it exploded in the upper atmosphere over and over until I GTX

Will post pictures before going to sleep.

EDIT:

ragequit gets auto-changed to GTX

EDIT2:

visitors can't see pics , please register or login

What a fruitless pursuit that was! 5 hours went by, and i haven't even passed 15km altitude.

(click to show/hide)

This one was my last hope. I managed to make it fly, but it lacks acceleration and stalls as soon as air gets thin. I will try gluing a rocket on it's ass tomorrow, though it will disbalance everything...

(click to show/hide)

Besides, burned half of my fuel under 15km

This will not do.

Thomek · « **Reply #71 on:** February 07, 2015, 11:28:26 am »

Quote from: Armpit_Sweat on February 07, 2015, 12:25:18 am

Interesting. Hmm, what is the theory behind the light body/fuselage?..
I don't know anything about real-life aircrafts or even engineering in general, but ( my ) common sense suggests keeping all mass in front of the center of thrust. In other words i try too have all the weight as close to the center of my craft as possible, while having engines as far behind as possible. ( excluding landers, rovers and other specialized stuff )
The sum/vector of all the thrust is in the center anyways, or that is not how physics works?.. I honestly don't know. Just having a "gutfeeling" that heavy wings and light body will make it spin and shake at some point.

Ah a simple mistake on my part. I meant center of thrust more in line with center of mass (center of mass= center of drag, in stock physics afaik..) Keeping the thing light is generally sensible no?

Anyway, I took the challenge and made something that barely works in FAR!

(click to show/hide)

I barely made it up there, have to transfer fuel from internal tank to the external engine tanks while coasting to apoapsis for circularization. Anyway I had tons of liquid fuel left, so I removed about 2.8 tonnes of it in the craft file.. Meaning the thing should have 2.8 tonnes of payload, at least.

Heres the craft: https://dl.dropboxusercontent.com/u/486399/FAR_ssto_mkIII_A.craft

Further development plans:
I need to tinker more with wings, as they seem much more powerful in FAR. Also, the engines don't need as much intakes as in stock I think. I'm considering trying to center at least 2 engines with the CoM, or even all of them. I can only use about 25% power when I switch to closed cycle without veering off. There might also be gains to simply installing a centerline engine at the back for orbital insertin and circularization, idk.. perhaps it will be too heavy, too far back.

There is also the small chance that the 40 liters of fuel in the in-line intakes is enough in an efficient climb. That would facilitate removing the liquid tanks entirely..

Anyway, the concept is proven

Try to keep around 120m/s vertical velocity through the climb. You should be at 30.000m and have ground velocity of 1400m/s when initiating orbital burn. (Press 1 to close intakes and switch to closed cycle) Be very careful with the throttle then, but point the aircraft as much up as you dare without stalling. You need to get out of the atmosphere quickly!

After getting an apoapsis of around 85k, start moving fuel from internal tank to outboard tanks. (press alt on outboard tanks, then internal, the move fuel OUT from internal tank.)

GL

Kafein · « **Reply #72 on:** February 07, 2015, 12:26:02 pm »

Play without mods you pussies, like real rocket scientists without a calculator

Thomek · « **Reply #73 on:** February 07, 2015, 03:19:35 pm »

Spaceplane so much easier without the FAR mod Kafein..

Argh I made a better, simpler one.. Estimate it can take 5-6 tonnes useful load to LKO, perhaps more. It does need more fuel than is stored in the back though.

https://dl.dropboxusercontent.com/u/486399/FAR_ssto_mkIII_B.craft

(click to show/hide)

edit: Made the best I can.. final one

10 tonnes to orbit, with FAR. This is the new truck to Orbit and beyond!

(click to show/hide)

.craft: https://dl.dropboxusercontent.com/u/486399/FAR_ssto_mkIII_C.craft

Armpit_Sweat · « **Reply #74 on:** February 08, 2015, 03:11:02 am »

Quote from: Thomek on February 07, 2015, 03:19:35 pm

edit: Made the best I can.. final one 10 tonnes to orbit, with FAR. This is the new truck to Orbit and beyond!

(click to show/hide)
visitors can't see pics , please register or login
.craft: https://dl.dropboxusercontent.com/u/486399/FAR_ssto_mkIII_C.craft

(click to show/hide)

In my first attempt I barely made it off the ground and spin-crashed about 200 m from the space center, because i over-pitched and lost too much speed...

(click to show/hide)

On the second run I reached around 22km, but overheated the engines so they popped one by one. Otherwise it was rather stable this time, but i snapped a pair of small winglets on the nose, cause I prefer as little manual effort as possible

I removed the cargo and adjusted c.o. mass and c.o. lift accordingly, to ease the test-runs:

(click to show/hide)

This time i got to 85 km but sadly had no fuel left to stay in orbit. Had otherwise a very positive experience! Never got so far on anything i have built myself

I am also impressed by the functional simplicity of your design, as it's often very hard to achieve in KSP. A surprisingly flawless performance of the single pair of RCS thrusters! I'm used to 4+4 "pattern", and expected a pair to be insufficient for such a large aircraft.

(click to show/hide)

Attached 27 t of rocket fuel, and re-adjusted wings according to the new weight. Wet and dry mass matched almost perfectly without my assistance!

And so, on my 4th test-run, i was finally able to achieve a "full orbit" on a 100% reusable craft with a horizontal take-off and landing! ( FAR + Deadly Re-Entry )!

visitors can't see pics , please register or login

In this great day, all of Kerbin is celebrating the genius of Thomek the Father of Kerbal SSTO development, and naming all the future series of SSTO crafts in his honor!

P.S.

Now i need to get them 3 Kerbals back to Kerbin

EDIT:

Have little fuel left, so landing would demand precision and careful planning. Having no chutes forces me to take a careful path of sending a rescue mission instead

Author Topic: Kerbal Space Program (Read 12344 times)

Molly

Re: Kerbal Space Program

Thomek

Re: Kerbal Space Program

Kafein

Re: Kerbal Space Program

Armpit_Sweat

Re: Kerbal Space Program

Kafein

Re: Kerbal Space Program

BlindGuy

Re: Kerbal Space Program

Armpit_Sweat

Re: Kerbal Space Program

Thomek

Re: Kerbal Space Program

Armpit_Sweat

Re: Kerbal Space Program

Thomek

Re: Kerbal Space Program

Armpit_Sweat

Re: Kerbal Space Program

Thomek

Re: Kerbal Space Program

Kafein

Re: Kerbal Space Program

Thomek

Re: Kerbal Space Program

Armpit_Sweat

Re: Kerbal Space Program