[KSP/RSS/Stock+DLC] Single stage, unrefueled mission to Venus and back with a 13.1t electric ssto.

[moar ssto]

   From my previous experimence with rapier-nerv ssto on Earth, I though that venus ssto, of any kind (I assumed prop-nerv conventional wing craft), was impossible, due to how hard it is to go past beyound 10000m/s on lvn while still having decent twr. However couple months ago, I saw that some people were discussing that some parts were capable of generating a lift/drag ratio of hudreds, so I searched through the parts and found the magic parts( an specific arrangements of certain parts, dm me for detailed construction, since Stratzenblitz75 has a lot cooler mission ahead that will explain the working of magic wings in detail, so I won't spoil it), we will call this setup the "magic wing" from now. I put this aside for a while, since I was not able to resolve the misterios torque this setup was producing, and hence completely unable to control my craft. However recently, I discovered that the solution was remarkebly simple, by simply putting the Col instead of the geometric centre of the "magic wing" exactly below the craft dry and wet com( which coincide with each other), I got close to 0 aerodynamic torque, hence I was able to control the vehicle with only reaction wheel, which means I can get craft l/d really close to the theoretical maximum l/d ratio of "magic wings",  after resolving the issue with takeoff and landing, I made a prototype electric ssto that can get into LEO with about 3000m/s of margin and about 7% of LEO payload fraction and only consuming 7900m/s of dv. This low dv use meant that I can reduce my twr a lot further, and hence put in a lot more xenon gas and having more dv. So I decided to do this mission, and the craft has following stats: 13.1t takeoff mass, 23500m/s of vacuum dv, 0.03 of initial vacuum twr, 2 ion engines powered solely by RTGs, 2 small dlc rotors, each with 6 R25 ducted fan baldes. To leo dv usage was about 8200m/s ,which leaves us with 15300m/s of dv, and the effective payload fraction was 33.9%, counting unused xenon tanks as payload. 

    Earth launch:https://imgur.com/a/Wx0L5eE

Edited October 4, 2020 by moar ssto

[moar ssto]

Transfer: while this craft has the dv to do a direct transfer to Venus, it doesn'y have the twr, to do it efficiently and accurately due to the large size of the final ejection burn of at least 300m/s. So what we did here was firts raising the opbit by using about 30 periapsis kicks, then get a lunar assist, which will throw us into a 1:1 resonnat orbit to Moon, then we will eject the Earth-Moon system with another moon assist, which will make us come back to Earth exactly one year later, encouneting Moon again in a retrograde orbit, and throwing us into another 1 year heliocentric orbit with a higher relative velocity to Earth. We will continue this process two more times, which will give us enough relative velocity to earth to allow as transfer to venus. However, neither our ejection direction or the phase angle of earth is correct, so the last Lunar assist will throw us into a resonnat orbit with earth, coming back several years later, which will raise our orbit such that we will intersect Earth at another position in the orbit, and a final assist will send us to Venus. To avoid nightime reentry and landing, we did another assist off of Venus into a Venus resonant orbit, that allows us to land in the daytime when coming back again (Still not perfect, and light was a bit dim when landed). TLI costs us 3160m/s in total, and TCM was less than 0.2m/s. https://imgur.com/a/POpLutX

Edited October 4, 2020 by moar ssto

[moar ssto]

Venus aerocapture, reentry and landing: Before aerocapture, we opened the cargo bay and deployed the blades to 0 degrees, so that it will be perpendicular to the airstream, acting as airbrakes. This was quite necessary, since otherwise the craft is baically dragless and we won't be able to capture into venusian orbit. The prop bades are thermally shielded by the heat shields and the crago bay, and the fairing is and the bay were were shielded by the heat shields. After the aerocpature, we will go straight for landing. During the decent, we point prograde and roll belly up or down to control direction of lift, hence decent. After getting to low speed, we float down close to surface with the cargo bays open. Just before landing, we started the rotors on low throttle, and reverse deployed the baldes, so that it generated upward thrust(backwards) allowing us to slowly touchdown, bakcwards.https://imgur.com/a/tiy8388

 

Edited October 4, 2020 by moar ssto

[DA299]

@moar ssto this is really impressive!!

Edited October 4, 2020 by DA299

[moar ssto]

24 minutes ago, DA299 said:

@moar ssto this is really impressive!!

Thank you so much!

[moar ssto]

Venus ascend: Taking off from Venus is usually considered one of the hardest things you can do with terrestrial bodies in RSS. However, for our craft, this is not true and the Venusian ascend is more or less an easier version of earth ascend, since our craft has props, so doesn't care about the superhigh pressures, and also our craft doesn't depend on intake air, like those more traditional rapier-nerv powered stock sstos for RSS. So the lessend orbital speed, gravity, increased twr due to fuel drainage and the steeper pressure profile of Venus really made this easier than Earth ascend. There are some cavietts though. Ascend starts by rising backwards as a helicopter just like on Earth, however we will start at a much lower rotor torque, hence rpm to ward off aero kraken, and also stop the craft from flipping due to it's naturaly stable orientation is going forwards and not backwars, due to prop and payload bay placement, as well as fairing orientation. We slowly increase throttle as air thins out, but the craft still flipped several times. Lucky, this didn't cause the loss of the vehicle, and we were able to fix it by letting it dive down by killing the throttle, then arrest the dive by going on high throttle then lowering the throttle to limit speed to safe level. After reaching one atm of pressure, we flip the baldes just like on earth, and the rest of the ascend onwards is fairly similar, there are some differences though: first, we got past m1 slightly due to Venus' lower speed of sound , hence lower bladepitch is required,  however, the lower speed of sound means we also needed to throttle down the rotors a bit, since if we push the balde airspeed too far beyound speed of sound, it will suddenly loose thrust (seems like a behavior built into the lift-mach curve of dlc ducted fan blades, so nothing you can do with that, only throttling down.) Anoter difference seems to be due to a typo in RSS Venus cfg, there is a negative sign missing from one line of the atmo curve, as a result, the craft entered wild wave like motion, luckily, this made us stuble into a better ascend trajectory(during testing phase, it got us into a worse trajectoty, so we were lucky this time). Orbit was reached with more than 4400m/s o dv, more than enough to tansfer home, with a margin of 1100m/s. dv usage was 7700m/s, with ignition twr of 0.04 and time to orbit was about 5 hours in game and more than 23 hours in real time.  https://imgur.com/a/7xIu8zS

Edited October 4, 2020 by moar ssto

[moar ssto]

Venus departure and transfer to Earth: While our craft has enough dv for a direct transfer, we still want to save dv and do things efficiently. However, unlike departing from Earth when  we had the Moon to help us, there is no gravity assist available for direct dv savings, so what we will do is to use resonnat orbit to split up the final ejection burn into two burns, which would be close to 300m/s if done all at once, hence could result in some losses and also more dv for correction. Also our inclination is not ideal to strat with, so doing resonnat orbits with Venus decreases dv usage, by allowing as to have final assist slingshotting into a trajectory closer to ideal, insted of using dv to get there, this saved us about 100m/s. The transfer plan was this: Firts using multiple periapsis kicks to eject into heliocentric orbit with 1:1 resonsnce with Venus, then when coming back to Venusian periapsis, we do the second part of the final ejection burn, which will eject us in the wrong direction, so instead of going to Earth, we well enter a 6:5 resonant orbit with Venus,  and the next assist will then slingshot us back to Earth.https://imgur.com/a/TAVTmAi

Edited October 4, 2020 by moar ssto

[moar ssto]

Earth aerocapture, reentry and landing: We aerocpature in a very similar way as at Venus, this time enetring a one day eliptical orbit after aerocapture and we renter. Reentry is different in that this time we are aiming for ksc, so we need to control our decend more carefully, at first, ksc was quite far away from out orbital path, so we roll the craft sideways to use it's lift to bend our trajectory north quite signifianctly, we also control decend by controlling belly pointing up or down just as with Venus, but with more care. We also open and close the cargo bay to actively control the drag this time, if we overshoot, then dive and open the bay, undershoot and rise and close tha bay. For some resons though, the terrain, which should really be green, appeared blue, so I had a hard time spotting Hainan from the ocean, nearly missing ksc if not checked the map view directly. When above ksc, we dive straight down until very close to ground and fired up the props moments before hitting the ground. The craft oscilated up and down for a while, before finally stabilising out and we carefully maneuvered the craft to the top of the Control tower( VAB top is far too bigger, so too easy), and landed with a bit of adjustment, then Bill evad out and paraglided back to the Astronaut complex. Due to the intense piloting, some parts of the flight have screenshots not taken, but video was recorded.https://imgur.com/a/N9aoNir

Edited October 4, 2020 by moar ssto

[moar ssto]

As a sidenote, accoridng to a testings on Eve and Jool in the stock system, without any modification, this carft can land and return from Laythe, Jool and Eve in one mission without refueling, with thousands of m/s of dv to spare. It has the dv to add a Duna landing, but it's prop baldes are insufficnet from preneventing it crashing into dunaian surface. So this is not only a RSS Earth and Venus ssto, but also a stock Eve and Jool ssto.

This mission has ended successfully, and videos hopefully will be soon released.

Edited October 4, 2020 by moar ssto

[moar ssto]

Next, I will test if this same craft can ssto from Saturn (just to LSO). Note that the RSS gas giants are technically landable, unlike jool.

Edited October 5, 2020 by moar ssto

[moar ssto]

After few days of test, it turned out that this craft can be a Saturn sea level ssto, with about 7km/s of margin.

[king of nowhere]

On 10/4/2020 at 1:46 PM, moar ssto said:

   From my previous experimence with rapier-nerv ssto on Earth, I though that venus ssto, of any kind (I assumed prop-nerv conventional wing craft), was impossible, due to how hard it is to go past beyound 10000m/s on lvn while still having decent twr. However couple months ago, I saw that some people were discussing that some parts were capable of generating a lift/drag ratio of hudreds, so I searched through the parts and found the magic parts( an specific arrangements of certain parts, dm me for detailed construction, since Stratzenblitz75 has a lot cooler mission ahead that will explain the working of magic wings in detail, so I won't spoil it)

 

i've been looking for efficient wings for an eve ssto of my own, and I have been hugely frustrated by the lack of available informations. I posted repeatedly in the "help" section and I got very little useful information. most people seem to think i shouldn't even try to look for solid aerodinamic data before designing a plane!

so i'll take this chance to ask someone who obviously knows it: what are those magic parts? how do i tell them from the others?

[moar ssto]

6 minutes ago, king of nowhere said:

i've been looking for efficient wings for an eve ssto of my own, and I have been hugely frustrated by the lack of available informations. I posted repeatedly in the "help" section and I got very little useful information. most people seem to think i shouldn't even try to look for solid aerodinamic data before designing a plane!

so i'll take this chance to ask someone who obviously knows it: what are those magic parts? how do i tell them from the others?

I used a mod called kerbal wind tunnel (correct CoL, also a aero analyser mod, should work as well), which displays lift to drag ratios of your crafts in the vab or sph at different simulated mach number and aoas. I distinguish magic wings as parts that have a better supersonic/hypersonic lift to drag ratios than conventional wings at certain aoas, which I remember is 3.15 @M1.15( the "real" sound barrier in ksp), 5.1@M3, and 3.15@Minfinity(>=M25). There is no systemetic way so far I found that can be used to distinguish magic wings from other parts, since they have different mechanism of work. Some are from broken drag cube, some are from hardwired drag reduction ,while others are from node occlusion eliminating most of the body drag. Just try with different parts by slapping them onto a low drag fuselage( node occluded cylindrical fairing), rotate te part of interest by 45 degrees, which usually is the angle where most magic wings peaks, and see which part works (use aoa curve display, and vary your speed to be >M3). It's not suprising that you won't get help from others, since magic wing is a topic known by only a handful of people, espiecially this kind I am using.

[Pds314]

L/D of *Hundreds* 

[moar ssto]

1 hour ago, Pds314 said:

L/D of *Hundreds* 

for the particluar setup, l/d starts with 100 ish at transonic, 600 ish at M5 and 400 ish above M25. The limiting factor is really the sonic barrier, right after ion ignition.

 

[camacju]

On 10/14/2020 at 8:25 AM, king of nowhere said:

what are those magic parts?

If you're still wondering how to use magic wings, there are actually better options than the "standard" magic wing which uses heat shields. The flat flag, if pointed upward at an angle of 45 degrees, gives enormous lift/drag ratios. I've gotten L/D in the hundreds of thousands with the right angle of attack. If you point the flag just below 45 degrees to prograde, you'll actually point the drag component forward, and create negative drag while still creating positive lift. You can infiniglide all the way to escape velocity using this trick as long as you have enough control to keep it stable.

[moar ssto]

On 1/26/2021 at 12:16 AM, camacju said:

If you're still wondering how to use magic wings, there are actually better options than the "standard" magic wing which uses heat shields. The flat flag, if pointed upward at an angle of 45 degrees, gives enormous lift/drag ratios. I've gotten L/D in the hundreds of thousands with the right angle of attack. If you point the flag just below 45 degrees to prograde, you'll actually point the drag component forward, and create negative drag while still creating positive lift. You can infiniglide all the way to escape velocity using this trick as long as you have enough control to keep it stable.

Yes, they do have good l/d, infinite in fact, but when you have a curved trajectory, ksp's rotation plysics will have a hard time keeping track of the lift,and what happens is that you will have positive or negtaive(in this case, thrust) induced lift. Flags also have very great l/m ratio, infact, better than convetional wings. The only drawbacks they have are being not heat torerant, there are ways to get around that, and one of them doesn't add any drag.