Duna Winged Aircraft Range Challenge

[OJT]

As we all know here, Ingenuity became the first aircraft to achieve powered flight on Mars. It also became the first rotorcraft to fly on another celestial body.
NASA, however, did consider winged aircraft first. There was ARES proposal that was ultimately abandoned in favor of Mars Phoenix program. There were Earth high-altitude research drones with adorable name "Mini-Sniffers" (pictured below) that could theoretically be adapted for Mars flight. And there is also a prototype solar glider Sky-Sailor developed by ETH Zürich that could be developed into a fully fledged mission if funding is provided

 

Thankfully, we are not limited by either budget or feasibility of such missions in KSP and, therefore, for this challenge, we will develop a Duna airplane

Mission Profile:

The plane will be stored inside a fairing and launched from Kerbin towards Duna. After reaching Duna, the plane will separate from main rocket and enter the planet's atmosphere and glide as far as it can before it either crashes or lands softly on the surface

Construction Rules:

• Only Stock parts are allowed, for both Plane and the Launch Vehicle
• Plane must be able to fit inside a 3.75 meter fairing. Fairing can NOT be made wider than its base, which means you will need to get creative with wing shapes or robotics in order to make the Plane fit
• Plane must be either an unpowered glider or be powered by electric props. Depending on that, your submission will be labeled either Unpowered or Powered
• Plane can be either Manned or Unmanned, that is up to your preferences
• If the Plane is Manned, the Kerbals aboard must survive the landing. Whether you choose to bail out and pull the parachute, attempt a soft landing or use the plane as an impact absorber is up to you, as long as all kerbals survive
• If the Plane is Unmanned, your save file must have CommNet enabled like on Normal difficulty. Don't forget to put an antenna on the Plane and couple of relays around Duna beforehand 
• Plane cannot have any means to recharge its batteries: no solar panels/fuel cells/RTGs and whatnot
• With that being said, you can keep the Plane fully charged for the transfer from Kerbin to Duna. Just make sure all recharging means are discarded before atmospheric flight phase
• Launch Vehicle must use 3.75 meter fairing to store the Plane
• Significant part clipping is only allowed for Plane fuselage optimizations. Minor part clipping of wings and control surfaces of the Plane is allowed, but don't overdo it. No part clipping for Launch Vehicles
• EDIT: I think the thread name already makes it pretty clear, but just in case: the Plane must have wing parts. Wingless gliders won't be accepted

Specific requirements for Powered submissions:

• Plane can only use no more than 100 electric charge to power the props. Rest of the flight must be performed unpowered
• Props can NOT be offset in any way. Prop offsetting can significantly reduce energy usage to the point of actually generating electric charge, essentially making an infiniglider. So, for the purpose of fairness, props can only be placed "normally" without additional fine adjustments

Challenge rules:

• The whole stack must be launched from KSC
• Only the Plane is allowed to enter Duna's atmosphere: non-essential equipment like transfer stages must be detached before atmospheric entry.
• You are, however, ALLOWED to do a braking burn and even enter Duna's orbit altogether if you want to, as long as you don't skim the atmosphere while doing it. As soon as you're ready for the Duna flight, all non-essential equipment must be discarded
• After entering the atmosphere, you are NOT allowed to escape back to space: once you're in - you're gliding through the air until the end
• There will be three scoring criteria: weight of the Plane, weight of the entire Launch Stack and Distance travelled. You must include a screenshot of the first two criteria from VAB/SPH with data shown, some screenshots from the mission itself and a final screenshot of the landing site. Third criteria might be tricky to measure in pure stock KSP, so I recommend Persistent Trails that can track your flight trajectory and distance : just start logging your glide as soon as you hit Duna's atmosphere and then make a screenshot of your travelled distance. Alternatively, you can try out @linuxgurugamer's edit of Persistent Trails: this one will start recording automatically as soon as you enter the atmosphere! Third option, if you prefer to play without mods, is to use KerbNet to mark your entry point and then calculate the distance by hand (check @18Watt's submissions for an example on how to do it)
• Speaking of mods: Mods that affect gameplay (physics changes or new parts) are not allowed. Information mods like KER and graphics mods are allowed

Submissions:

OJT

Unpowered, Unmanned. Plane Mass - 931 kg; Launch Stack Mass - 66.439 tons; Distance - 596.421 km

Unpowered, Manned (2 Kerbals). Plane Mass - 1722 kg; Launch Stack Mass - 62.794 tons; Distance - 754.295 km

Unpowered, Unmanned. Plane Mass - 707 kg; Launch Stack Mass - 61.325 tons; Distance - 24478.43 km

18Watt

Powered, Unmanned. Plane Mass - 804 kg; Launch Stack Mass - 125.562 tons; Distance - 1189.709 km

Powered, Unmanned. Plane Mass - 804 kg; Launch Stack Mass - 125.662 tons; Distance - 1509.905 km

Unpowered, Manned (1 Kerbal). Plane Mass - 1188 kg; Launch Stack Mass - 126.188 tons; Distance - 12593.132 km

Powered, Manned (1 Kerbal). Plane Mass - 1435 kg; Launch Stack Mass - 66.82 tons; Distance - 1946.392 km

linuxgurugamer

Unpowered, Unmanned. Plane Mass - 4330 kg; Launch Stack Mass - 418.639 tons; Distance - 1808.855 km

Unpowered, Unmanned. Plane Mass - 4330 kg; Launch Stack Mass - 418.639 tons; Distance - 2792.045 km

kerbalboi

Unpowered, Unmanned. Plane Mass - 1065 kg; Launch Stack Mass - 235.333 tons; Distance - 9148.058 km

 

 

Good luck! 

Edited January 16, 2023 by OJT

[18Watt]

This looks interesting.  I’m finding it much more difficult than I thought it would be.  

[OJT]

Okay, so I quickly threw something together to get on the board and have something that other potential contenders can compare against

First off is the Plane

Foldable wings, unmanned, unpowered and mass of 931 kg

Here's the Launch Stack

Twin-Boar first stage, Poodle second stage and 66.439 tons of mass

Launch and transfer to Duna is standard, so I'm not gonna get into too much detail

Spoiler

Unfolding the wings and deploying the Plane

Spoiler

As soon as I hit 50km altitude, I engage Trail tracking. Turns out, it does measure the exact distance travelled, so that's a plus!

Spoiler

I went deep into the atmosphere in order to aerobrake enough so that the Plane doesn't skip back into space. After that I just kept the Plane level and tried to carry as much speed as I could

Spoiler

The Plane couldn't carry its glide anymore, so it hit the face of a mountain

Spoiler

Final distance is 596.421 km. Just shy of 600 km, which is also almost 1/3 of the Duna's circumference!

[OJT]

Also, I read through my rules again and decided to slightly adjust some of them

• I realized that if you make a Powered Unmanned Plane with only 100 EC, after the prop motors run out of juice you will lose control of the plane aswell, since probe core will also run out of charge. For that reason, I will allow to carry more electric charge. However, you are not allowed to use more than 100 EC during powered flight: for example, you can initially glide unpowered, then engage the motors, then after using no more than 100 EC disengage the motors and continue to glide unpowered
• Also, Planes are not allowed to have means to recharge the batteries altogether: this requirement is no more limited to Powered submissions only. You are still allowed to keep the Plane fully charged during interplanetary transfer, just make sure that Plane can't be recharged once it decouples from Launch Stack

OP will be updated accordingly

8 hours ago, 18Watt said:

This looks interesting.  I’m finding it much more difficult than I thought it would be.

I guess it is a matter of perspective, but it is easier than you think. As soon as you figure out how to fit the Plane into the fairing bay, the rest is quite easy. The devil is in the details or, in this case, the optimizations 

[18Watt]

2 hours ago, OJT said:

realized that if you make a Powered Unmanned Plane with only 100 EC, after the prop motors run out of juice you will lose control of the plane aswell, since probe core will also run out of charge

Yeah, that is certainly an issue.

2 hours ago, OJT said:

Planes are not allowed to have means to recharge the batteries

My entry is going to be outside the bounds of the challenge.  I'm not going to use solar for the entry, but I'm gping to have solar for the craft.  Also, I'm planning on having 400 EC on the craft.  Actually, 405 EC, the probe core I'm using actually has 5 EC. I'm making a glider, but one which can biome-hop.

This is actually a pretty fascinating challenge!  I'm deviating significantly from the challenge parameters, so my entries will likely be excluded from the leaderboards.  But I'm finding a better way to land on Duna!!

 

[OJT]

19 minutes ago, 18Watt said:

My entry is going to be outside the bounds of the challenge.  I'm not going to use solar for the entry, but I'm gping to have solar for the craft.  Also, I'm planning on having 400 EC on the craft.  Actually, 405 EC, the probe core I'm using actually has 5 EC.

I can't quite understand how your Plane deviates from challenge rules. You can have means to generate electricity on Launch Vehicle, and you can use these means to keep the Plane charged up until it is time for atmospheric entry. From what I understood, your craft seems to be within challenge requirements

As for the charge, my ~600 km unpowered glide used up less than 100 EC, so 405 EC can potentially be a bit of an overkill. But it depends on how long you plan to fly

[18Watt]

11 minutes ago, OJT said:

I can't quite understand how your Plane deviates from challenge rules

Well, I'm celebrating, and not explaining clearly.  

I'm going to have 405 EC on the entry craft, which is over the 100EC limit.  However, the 100 EC limit is (I think) only for powered arrivals.  My lander will have propellers, but I'm not planning on using the propulsion (propellers) for the landing, so I'm probably ok with the extra EC- because my arrival will not be powered.

Also, my craft will have solar panels, which again is kinda forbidden.  However, I think the solar panel prohibition is to limit 'glide' distance.  As before, since I'm not planning a powered arrival, I think the solar panels are OK.  The solar panel on my lander is an extendible one, so not really useful while moving through the atmosphere.

Ahh, you'll see.

I have struggled with this challenge, but when it's all said and done, I think I have a new preferred Duna arrival method.  I had no idea that fixed-wing designs could be so effective on a body with such a thin atmosphere.  Really enjoying this challenge!

 

[OJT]

23 minutes ago, 18Watt said:

I'm going to have 405 EC on the entry craft, which is over the 100EC limit.  However, the 100 EC limit is (I think) only for powered arrivals.  My lander will have propellers, but I'm not planning on using the propulsion (propellers) for the landing, so I'm probably ok with the extra EC- because my arrival will not be powered.

100 EC limit is the usage limit for the prop motors. If your Plane has prop motors and 405 EC total charge, you can only use 100 units out of the total 405 to power the motors. The rest can be kept to not lose control of the probe core

23 minutes ago, 18Watt said:

Also, my craft will have solar panels, which again is kinda forbidden.

That is true, solar panels are forbidden. However, extendable solar panels don't generate charge when they are concealed, so the submission can still be valid "in spirit". I'm actually curious on what you're cooking up

23 minutes ago, 18Watt said:

I think I have a new preferred Duna arrival method.  I had no idea that fixed-wing designs could be so effective on a body with such a thin atmosphere.

Fixed wing aircraft on Duna can be surprisingly viable. Yes atmosphere is thin, but it is not as thin as on Mars (around 10 times denser than Mars Sea Level in fact), and at the same time it is thin enough to make good use of vacuum-optimized engines. The biggest challenge from my experience is inertia: combination of thin atmosphere and lower gravity means that turns are much wider on Duna and if you are, for example, aiming for a landing, you need to make your corrections way beforehand in order to touchdown smoothly. You also need to really increase wing area if you plan to land with sensible speeds, but I think that's a given

Edited December 24, 2022 by OJT

[camacju]

Are ram air turbines allowed to generate electricity? You wouldn't be getting any "free" energy from it, since it uses your plane's forward motion to generate power and creates drag.

[OJT]

11 hours ago, camacju said:

Are ram air turbines allowed to generate electricity? You wouldn't be getting any "free" energy from it, since it uses your plane's forward motion to generate power and creates drag.

No, since it is still a mean to generate electricity, even if a quite creative one. Determining how much EC exactly your Plane needs for the glide phase is part of the design challenge

[18Watt]

Here's my first attempt at a fixed-wing Duna lander.  It should function as a biome-hopper on Duna also.

Launch and Duna arrival:

Spoiler

Here's a shot in the SPH.  One of the design requirements was that the plane fit inside a 3.75 m fairing, without having to bulge out the fairing.

Mounted to a rocket.  Launch cost a little under $50K, but it has far more dv than I actually need to get to Duna.

In the next screenshot, you might notice my staging isn't quite right.  I have the fairing set to deploy after dropping the first set of SRBs, but before the second set.  That was a mistake, I had to redo the launch.  Dropping the fairing at that point is still deep in Kerbin's atmosphere.  Oops.

Here's another launch attempt, this time with the staging set better.

Arrived at Duna, and on a trajectory which puts me in Duna's atmosphere, with a PE of about 20 km.  The solar panels are deployed to keep the batteries charged, but they need to be stowed before hitting Duna's atmosphere, which begins at 50 km.

Landing:

Spoiler

Just entering Duna's atmosphere at 50 km.  Solar panels need to be stowed while moving in the atmosphere.

I forgot to take screenshots of the level-off.  I was actually able to level off at ~32 km, with a speed of around 800 m/s I think.  However, I did not attempt a long glide, because I found a relatively flat-ish area, and dove for it.

The plane actually is able to fly as slow as about 40 m/s on Duna, at least at low elevations.  Duna has some large elevation changes, and I haven't tested the craft at higher landing elevations yet.  Main landing gear is retractable, nose gear is fixed.

Yes, I used almost 100 EC in the short glide from orbit, without ever powering up the propellers.  I do have a small reaction wheel on board, which I think is the biggest power drain.  The plane will actually fly fine with the reaction wheel disabled, but I left it powered on for the entire descent.

Bleeding off speed happens slowly with Duna's thin atmosphere.

Landed.

Solar panel deployed to top off the battery.

Short test flight:

Spoiler

The plane requires a long takeoff run, because it accelerates very slowly.  I have 8 small fan blades per rotor, perhaps adding additional blades would aid in accelerating.

The plane can lift off at about 35 m/s, then slowly gains speed.

The plane can hit much higher speeds than this.  I need to fiddle around with power and blade settings to determine an efficient cruise profile.  The small rotors are set to about 20% size in the VAB, and even then I am only using a fraction of the available torque.  Turning off the reaction wheels should give me more range too.

Landed again after the short hop, deploying the solar panels again.

I didn't really make a good attempt at the challenge, this run was just playing around, proof of concept.  It does seem like a really good way to get things to the surface of Duna.  No parachutes or rocket engines needed, and you have the ability to select your landing site with much more precision than I normally am able to get just doing ballistic entries.

For further testing, I'm curious how much range I can get out of the thing.  The 100 EC limit of the challenge seems very appropriate.

[OJT]

32 minutes ago, 18Watt said:

Here's my first attempt at a fixed-wing Duna lander.  It should function as a biome-hopper on Duna also.

Launch and Duna arrival:

  Reveal hidden contents

Here's a shot in the SPH.  One of the design requirements was that the plane fit inside a 3.75 m fairing, without having to bulge out the fairing.

Mounted to a rocket.  Launch cost a little under $50K, but it has far more dv than I actually need to get to Duna.

In the next screenshot, you might notice my staging isn't quite right.  I have the fairing set to deploy after dropping the first set of SRBs, but before the second set.  That was a mistake, I had to redo the launch.  Dropping the fairing at that point is still deep in Kerbin's atmosphere.  Oops.

Here's another launch attempt, this time with the staging set better.

Arrived at Duna, and on a trajectory which puts me in Duna's atmosphere, with a PE of about 20 km.  The solar panels are deployed to keep the batteries charged, but they need to be stowed before hitting Duna's atmosphere, which begins at 50 km.

Landing:

  Reveal hidden contents

Just entering Duna's atmosphere at 50 km.  Solar panels need to be stowed while moving in the atmosphere.

I forgot to take screenshots of the level-off.  I was actually able to level off at ~32 km, with a speed of around 800 m/s I think.  However, I did not attempt a long glide, because I found a relatively flat-ish area, and dove for it.

The plane actually is able to fly as slow as about 40 m/s on Duna, at least at low elevations.  Duna has some large elevation changes, and I haven't tested the craft at higher landing elevations yet.  Main landing gear is retractable, nose gear is fixed.

Yes, I used almost 100 EC in the short glide from orbit, without ever powering up the propellers.  I do have a small reaction wheel on board, which I think is the biggest power drain.  The plane will actually fly fine with the reaction wheel disabled, but I left it powered on for the entire descent.

Bleeding off speed happens slowly with Duna's thin atmosphere.

Landed.

Solar panel deployed to top off the battery.

Short test flight:

  Reveal hidden contents

The plane requires a long takeoff run, because it accelerates very slowly.  I have 8 small fan blades per rotor, perhaps adding additional blades would aid in accelerating.

The plane can lift off at about 35 m/s, then slowly gains speed.

The plane can hit much higher speeds than this.  I need to fiddle around with power and blade settings to determine an efficient cruise profile.  The small rotors are set to about 20% size in the VAB, and even then I am only using a fraction of the available torque.  Turning off the reaction wheels should give me more range too.

Landed again after the short hop, deploying the solar panels again.

I didn't really make a good attempt at the challenge, this run was just playing around, proof of concept.  It does seem like a really good way to get things to the surface of Duna.  No parachutes or rocket engines needed, and you have the ability to select your landing site with much more precision than I normally am able to get just doing ballistic entries.

For further testing, I'm curious how much range I can get out of the thing.  The 100 EC limit of the challenge seems very appropriate.

The whole concept looks decent in general. And retractable solar panel can't really be deployed during atmospheric flight or it will get ripped off, so your Plane could satisfy the "no recharging during flight" rule in spirit. However I have to be firm, stick to the letter and sadly deny this post as a viable submission

Still, from the looks of it you already have a 99% ready submission for Powered category. You simply need to remove the solar panel and focus a bit more on gliding rather than finding a good landing spot. If you already have a savefile at Duna transfer window, giving it a second attempt shouldn't take very long

With that being said, couple of notes for the future: I need the mass of the Plane alone and I will also need the distance flown after entering atmosphere. I know you like to play the game purely Stock, but it is gonna be very hard for you to calculate the distance. Get yourself Persistent Trails to save yourself the mathematical hassle, link is in the OP 

32 minutes ago, 18Watt said:

 The 100 EC limit of the challenge seems very appropriate

If you're making a self-imposed rule of not using more than 100 EC, it's fine. But I kind of get the feeling that you didn't quite understand the adjusted 100 EC rule. You can have as much electric charge on board of your Plane as you wish. 100 EC limitation is exclusively for powered flight

Let's take your Plane for example: it has 405 EC. You enter the atmosphere and glide. By the time the plane starts to noticeably slow down you have, say, 350 EC left. You engage the prop motors to accelerate and extend your range. Once your charge hits 250 EC, you disengage the motors and continue to glide unpowered

When I wrote the initial version of the rule I had Manned Planes in my mind, and Kerbals can control the winglets and other control surfaces without any EC, so you could have 100 EC to power the motors and then glide the rest of the way. If you were to make a unmanned Drone, the probe core needs charge for basic control, which would make the motors borderline unviable. I imagined the EC limit for Powered Planes as both a range extender AND another avenue for optimization, since now if you wanted to squeeze out more range, you need to play around with motor parameters, prop angles and other things instead of just adding more batteries. Hence, my adjustment to the rule

So you CAN have more than 100 EC on your Plane. You're just not allowed to use more than 100 EC for powered flight. The rest of the glide must simply be done unpowered

Edited December 25, 2022 by OJT

[18Watt]

11 minutes ago, OJT said:

I need the mass of the Plane alone and I will also need the distance flown after entering atmosphere.

I actually have an idea about that, which should give me a rough estimate of distance traveled.  I'll make a note of my lat/lon at entry, and do a great circle calculation based on my final resting place.  Which sounds gloomy after I said it that way.  

 

11 minutes ago, OJT said:

If you're making a self-imposed rule of not using more than 100 EC, it's fine. But I kind of get the feeling that you didn't quite understand the adjusted 100 EC rule. You can have as much electric charge on board of your Plane as you wish. 100 EC limitation is exclusively for powered flight

Aha!  That makes more sense!  My concern with powered flight with a 100 EC battery is that the probe core would go dark after I used up the 100 EC.  The way I understand it (now) is that I can be powered for 100 EC.  Then the rest of the flight needs to be unpowered, but I'm still allowed to have extra EC on board to power the probe core?  That seems much more do-able.  

11 minutes ago, OJT said:

When I wrote the initial version of the rule I had Manned Planes in my mind

Once I get a feel for this, I do intend to build a manned glider as well.

I'll probably do a few more runs tonight.  It appears somebody left some milk and cookies laying around, so I'll have plenty of snacks.

Edit:  Kudos for specifying no prop offsets.  I wish I had added that rule for some of my own past challenges, but sadly I didn't even know about it.  Even so, I suspect you and @camacju will be able to exceed my attempts.  But I'm doing this one for fun, which it indeed is!

 

[OJT]

3 minutes ago, 18Watt said:

My concern with powered flight with a 100 EC battery is that the probe core would go dark after I used up the 100 EC

And that's precisely the reason I adjusted the initial rule. Your current understanding of the rule is correct: have as much charge on board as you want, but only use no more than 100 units to power the motors

4 minutes ago, 18Watt said:

I'll probably do a few more runs tonight.  It appears somebody left some milk and cookies laying around, so I'll have plenty of snacks.

Sounds like a nice holiday morning/afternoon/evening (depending on where you live ). Good luck!

[18Watt]

Well, I'm having a good second attempt.  My estimate right now is my props will carry me an additional 335 km on 100 EC.  I have the EC draw down to 0.04 at about 138 m/s at 8500-9000 m altitude.  The probe core draws 0.03 EC, so I have the motor draw down to roughly 0.01 EC.  But total draw is 0.04, so the batteries are only going to last about 2400 seconds (about 40 minutes) before I'll need to shut the engines off at the 100 EC limit.

Hope I don't crash.  I actually lost com signal for about 3 minutes during the entry, and bled off speed at an alarming rate while without any probe control.  And I even went overboard with relay satellites- I have six relay satellites around Duna, and still managed to lose signal for a few minutes.

 

[OJT]

Another Unpowered submission. This time it is Manned with two kerbals onboard

1722 kg with both kerbals onboard, 1534 kg empty weight

Launch Vehicle turned out to be a bit lighter than in my Unmanned submission, at 62.794 tons

Launch and transfer to Duna

Spoiler

Approaching Duna, decoupling from transfer stage and unfolding the wings

Spoiler

I reentered a bit higher and aerobraking forces were still enough to stay in the atmosphere. There was still decent margin left infact which can noticeably prolong the glide. As always, Flight tracking was turned on as soon as I hit 50km altitude mark

Spoiler

I put landing wheels on my glider, and wing area would be enough to land at sensible speeds according to my calculations. However, I kinda forgot that I have Parallax with colliders on and I was landing at night, so I could barely see where I was landing

Spoiler

As a result, the plane crashed into the rocks. Good news: both Kerbals survived, so this makes the submission legitimate

Final flight distance of 754.295 km, good improvement over my first try

2 hours ago, 18Watt said:

Even so, I suspect you and @camacju will be able to exceed my attempts.  But I'm doing this one for fun, which it indeed is!

Goal of this challenge isn't really in just the lowest weight or furthest distance. The rules are broad enough to allow lots of creativity. You can make very complex wing folding mechanisms, make a passenger carrier, maybe even a cargo glider? Possibilities are endless, I'm curious what people can build up 

[18Watt]

My second Entry:

Launch details:

Spoiler

Plane itself, cost of $9,514, weight of .804 t.

Launch vehicle, with plane inside fairing.  Launch cost $39,136, launch mass 125.562 t.

I'm going to start my glide from a 120X120 km equatorial orbit.

My entry will be from 120 km, with a PE of 30 km.  It will be night at the point I enter the atmosphere.

The Glide:

Spoiler

Here's my entry point, I'll calculate glide distance by doing a great circle calculation.

I managed to level off at 36 km.

I actually managed to climb back up a little.  That was not my intention, probably a waste of kinetic energy.  But I overshot my target of level flight just a tad.  I'm flying the entry with reaction wheels inactive to save EC.

Crikey!  I lost comms!  Thankfully the airplane is stable enough it just maintains pitch.  But my pitch becomes really high, bleeding off more speed than is probably ideal.

You'd think my 6 relay sats in orbit of Duna would be enough to maintain coverage.  Nope.

Phew!  Comms regained.  Let's see if we can salvage this attempt now.

Running out of energy, and the air is getting thick enough to really slow me down.  I will crank up the propellers at about 8 km.

Powered flight:

Spoiler

I start up the propellers at 334 EC.  Note to self, I need to shut off the propellers at 234 EC.  Just to be safe, I'll shut them down when I hit 235 EC.

My initial guess was that I'd get good results between 7 and 8 km altitude.

After a little fiddling, I found I was getting better performance above 8 km.  I got the EC draw down to 0.04, and 0.03 of that is from the probe core!

I was able to cruise at 135+ m/s, with a total EC draw of 0.04.  That should keep me in the air for about 2400 seconds (40 minutes), and at 135+ m/s that gives me an additional 325 km from the 100 EC I'm allowed to burn with engines running.  That's back of napkin math, but should be a pretty good guess.

At 235 EC I shut the engines off.  That puts my EC use at 99 units with engines running.  Notice it's becoming night again, and the terrain ahead doesn't look very flat.  I entered the atmosphere at dark, and will be landing at dark too.  I didn't plan that very well, but I didn't expect to be able to cover this much distance either.

Landing gear extended, lights on.

That's slower than ideal, but I made the landing work.

Well, I kinda made the landing work.  I ended up bouncing around a bit, and broke one of the elevons.  But the rest of the plane is intact, good enough.

Here's the coordinates where I came to a stop.

Result:

Mass of plane:  0.804 t.

Mass of assembled launch vehicle (including plane): 125.562 t.

Distance covered in atmosphere: 820.91 km  1189.709 km  Calculated using great circle formula with start and end coordinates.

Category: Unmanned, powered flight using 100 EC total during powered phase.  (rotors and probe core combined..)

Edit:  I'm sure I could have gone much farther with a higher entry speed.  Just a suggestion, but it might make sense to specify a maximum AP around Duna for the entry, to more easily compare entries.

Edited December 25, 2022 by 18Watt
Calculation Error

[OJT]

@18Watt Looks pretty good! Adding you to the scoreboard now

[18Watt]

@OJT, I have a correction to my previous entry.  I did a great circle calculation, based on my lat/lon entry and landing locations.  Turns out that calculation determines the shortest great circle distance between two points.

However, I actually covered more than 180 degrees of longitude during my glide / powered-glide.

So my actual distance covered is the circumference of Duna (2,010.619 km) minus the short great circle distance between my two points.

So my previous glide actually was 1189.709 km.

I'm currently doing another entry with the same craft, but with a much higher entry speed.  Should be able to go farther, I'll let ya know!

 

[18Watt]

@OJT, here's a new entry.  Unmanned, powered, with a glide distance of 1,509.905 km.

Ship and launch:

Spoiler

Ship is identical to my previous attempt, except I put an antenna which could communicate to Kerbin for a mid-course maneuver to Duna.  I can almost fly to Duna in my sleep now..

For this entry, I'm going retro-grade.  I'm also not capturing at Duna prior to entry- I'm going to enter the atmosphere direct from the transfer from Kerbin.  So I'll have higher speed.

Screenshot showing the only change to my previous attempt- a big 'ol antenna to communicate with Kerbin on the transfer stage.

Atmospheric entry at Duna.  Entered at 0.2S, 60W.  I'm going retrograde (west..).

Glide:

Spoiler

I was able to level off slightly above 30 km.  For several minutes the challenge was keeping enough downforce to keep my plane inside the atmosphere.  Which I did with room to spare.

Eventually I got my AP under 50 km.  I'm safe at this point, don't need to worry about being ejected outside the atmosphere.

After atmospheric capture (PE below 50 km) I had enough energy to climb back up to almost 40 km.

After a very long glide I'm back into the soup, and ready to start the propellers.

Powered Glide:

Spoiler

Starting engines at 345 EC (just after this screenshot..)

I tried using an autopilot mod for the glide, but it just messed me up, probably lost at least 100 km monkeying with the autopilot.  I should have leveled off at about 9 km, but kept trying to make the autopilot work, just messed me up.

Stopped powered flight after 99 EC used.  Again, most of the EC usage was due to the probe core.  I did not fly the entry with the reaction wheels active because the reaction wheels eat up a lot of EC.  I only have 100 EC to use after starting the engines..

Unpowered glide after turning off the engines.  The additional EC draw is (currently) due to turning on the landing lights.  Prior to landing I will also activate the reaction wheels for additional control- but I don't really need the reaction wheels until the actual landing.

Final location- 0.7N, 29.65E.  I covered about 3/4 of the circumference of Duna in the glide.

Results:

Plane stats:  $9,514, 0.804 t.  (Same as my previous run)

Launch costs including plane:  $40,636, 125.662 t.  (Slightly higher than previous run due to an antenna addition..)

Total glide distance:  1,509.905 km.

Notes:

Spoiler

I'm calculating my distance by using a great circle calculation, taking the difference between my location at atmospheric entry and my landing location.  

Since I'm traveling more than half-way around the planet, I subtract the great circle distance between the two points from the circumference of Duna.  Yes, if Duna is not perfectly spherical (I suspect it is not) then there could be errors in my calculation.  However, it should be pretty close, I estimate less than 3% error, probably less.

 

Edit:  I I was going to improve my glide distance, I would probably do two things:  Increase my entry speed, by burning to accelerate just prior to atmospheric entry.  And also I think I could enter with a slightly higher PE and still stay in the atmosphere.  I really did not have much trouble staying in the atmosphere with a PE of 28 km on a direct arrival from Kerbin.

Edit #2:  I think I have an even better plan to maximize glide distance.  But keeping that a secret for now...

[OJT]

18 minutes ago, 18Watt said:

Yes, if Duna is not perfectly spherical (I suspect it is not) then there could be errors in my calculation.  However, it should be pretty close, I estimate less than 3% error, probably less.

From what I know, KSP doesn't simulate flattening of the planets, so I assume that all planets are, more or less, perfect spheres. Your calculations should still work, but like I said, Persistent Trails is still an option if you want to eliminate any errors 

Your latest submission is going on the scoreboard, and I will also correct your previous record. I am, unfortunately, busy with exam preparations so I don't really have time to play a lot of KSP and improve my results, but I am looking forward to seeing further improvements from you and (hopefully) submissions from other players 

[18Watt]

@OJT, I have a new entry.  Manned, Un-Powered.  Glide distance 12,593.132 km.  Roughly 6.25 times around the planet.  In the atmosphere.

Plane and launch deets:

Spoiler

The plane costs $6,919, and weighs 1.188 t.  One lawn chair for the Kerbal, which will be Jeb.  I did not want to have a probe core (they use EC), but I need one for KerbNet access to keep track of how far I travel.  Turns out you can activate KerbNet, then put the probe core into hibernation, and KerbNet will still work.

Assembled launch vehicle.  $41,723, weighs 126.180 t.

Just prior to entering the atmosphere.  I'm basically going to drop into a 51X49 km orbit.  I'll detach the transfer stage prior to atmospheric entry.  Actually, I'll turn and burn to keep the transfer stage out of the atmosphere completely- it has another relay antenna on it, which I want to keep!

The glide part 1:

Spoiler

Atmospheric entry occurs at 85.7E.  (85 deg 40').  I'll pass this spot 6 more times.

I was shooting for a PE of 49 km, but I overshot a tad due to the ejection force on the decoupler being set too high.  In the next screenshot, I'm at PE, and my AP is below 50 km.  That will continue to drop, and will be down to about 49.75 km by the time I get back to the AP.

Here's a shot of the glider.

The glide, part 2:  (Landing gear issues...)

Spoiler

Completed Lap 1.  Each lap ends up taking me roughly 41 minutes.

Lap 2:

Lap 3:

Lap 4:

Lap 5.  My PE and AP are getting pretty low.  Can I make it one more time around?

Yes!!!  Lap 6!!!  And I still have enough energy to go about a quarter around Duna from here!

Thank goodness I'll be landing in daylight.  Turning towards a relatively flat looking spot.

You can't see it, but I have a BIG problem in this next screenshot.  I adjusted the location of the nose landing gear, and didn't bother testing it.  It won't deploy because it's too deep inside the fairing!  And because I think I'm an ace pilot I waited until below 200m to extend the landing gear.  Well this could be a huge problem.

I ended up deploying the fairing, and managed to cycle the gear before touching down.  The less said about that landing the better, it was ugly.  But surprisingly, nothing broke.

 

Final Stats:

Plane:  $9,619, 1.188 t.  Manned (Kerballed), Un-Powered.

Assembled launch vehicle: $41,723, 126.188 t.

Duna's circumference:  2,010.619 km.  6 laps around Duna = 12,063.714 km.

Great circle distance for extra glide (about 1/4 around Duna) :  529.418 km.

Total Glide:  12,593.132 km.

[OJT]

5 hours ago, 18Watt said:

@OJT, I have a new entry.  Manned, Un-Powered.  Glide distance 12,593.132 km.  Roughly 6.25 times around the planet.  In the atmosphere.

Plane and launch deets:

  Reveal hidden contents

The plane costs $6,919, and weighs 1.188 t.  One lawn chair for the Kerbal, which will be Jeb.  I did not want to have a probe core (they use EC), but I need one for KerbNet access to keep track of how far I travel.  Turns out you can activate KerbNet, then put the probe core into hibernation, and KerbNet will still work.

Assembled launch vehicle.  $41,723, weighs 126.180 t.

Just prior to entering the atmosphere.  I'm basically going to drop into a 51X49 km orbit.  I'll detach the transfer stage prior to atmospheric entry.  Actually, I'll turn and burn to keep the transfer stage out of the atmosphere completely- it has another relay antenna on it, which I want to keep!

The glide part 1:

  Reveal hidden contents

Atmospheric entry occurs at 85.7E.  (85 deg 40').  I'll pass this spot 6 more times.

I was shooting for a PE of 49 km, but I overshot a tad due to the ejection force on the decoupler being set too high.  In the next screenshot, I'm at PE, and my AP is below 50 km.  That will continue to drop, and will be down to about 49.75 km by the time I get back to the AP.

Here's a shot of the glider.

The glide, part 2:  (Landing gear issues...)

  Reveal hidden contents

Completed Lap 1.  Each lap ends up taking me roughly 41 minutes.

Lap 2:

Lap 3:

Lap 4:

Lap 5.  My PE and AP are getting pretty low.  Can I make it one more time around?

Yes!!!  Lap 6!!!  And I still have enough energy to go about a quarter around Duna from here!

Thank goodness I'll be landing in daylight.  Turning towards a relatively flat looking spot.

You can't see it, but I have a BIG problem in this next screenshot.  I adjusted the location of the nose landing gear, and didn't bother testing it.  It won't deploy because it's too deep inside the fairing!  And because I think I'm an ace pilot I waited until below 200m to extend the landing gear.  Well this could be a huge problem.

I ended up deploying the fairing, and managed to cycle the gear before touching down.  The less said about that landing the better, it was ugly.  But surprisingly, nothing broke.

 

Final Stats:

Plane:  $9,619, 1.188 t.  Manned (Kerballed), Un-Powered.

Assembled launch vehicle: $41,723, 126.188 t.

Duna's circumference:  2,010.619 km.  6 laps around Duna = 12,063.714 km.

Great circle distance for extra glide (about 1/4 around Duna) :  529.418 km.

Total Glide:  12,593.132 km.

I guess that was the secret better idea of getting more range. I had similar idea about gliding further, but I didn't expect that the difference would be that drastic

Nice work! And I admire your willingness to land the craft intact, even when that isn't necessary for the challenge. I'm, however, curious on why your Launch Vehicle is so heavy? I am getting enough deltaV from my Launch Vehicles with half the mass, and our Planes have similar weights. My transfer stage even has half of its fuel drained because I was getting too much dV, and I would still have enough fuel to eject from Kerbin and even capture at Duna if I wanted to

Edit: One more question. Is Plane mass with or without Kerbal? Command chairs don't have a Kerbal by default, so the mass in SPH might be without Kerbal

Edited December 28, 2022 by OJT

[QF9E]

I think one could pretty much fly endlessly in the upper atmosphere, by making a craft that has a fairing as its root component, and fully occluding the forward and backward nodes - that way it will not generate any drag when flying prograde. As to how to get it into a 49.9 x 49.9 km orbit: from an orbit just above the atmosphere (I started with a 50.001 km circular orbit) lower PE into the atmosphere. While in the atmosphere, fly with the nose pointing in the normal direction (i.e., sideways on, so that the craft does induce drag) until drag lowers AP to 49.9 km and then turn prograde to cancel all drag.

I tried it (although I cheated my craft into Duna orbit) and completed a full orbit in this way without AP or PE degrading noticeably.

[18Watt]

5 hours ago, OJT said:

I'm, however, curious on why your Launch Vehicle is so heavy?

Yes, it is much heavier than needed.  The adapter from 3.75 m down to 2.5 m makes a good transfer stage, but has about 4,000 dv, which is about 3,000 more than needed to reach Duna.   I basically just slapped together a booster underneath it to get to orbit, without optimizing.  Ideally, I would drain at least half the fuel out of the adapter, and build a much smaller booster.

I would add that while it’s heavier than other entries, the launch cost is actually less than most other entries.  
 

5 hours ago, OJT said:

Is Plane mass with or without Kerbal?

Plane mass shown is with a Kerbal and jet pack, no parachute.

Oddly, the mass of the assembled launcher may or may not be with a Kerbal.  I mistakenly thought that when I brought the plane from the SPH to the VAB that the installed Kerbal would come with it.  Nope.  I got all the way to atmospheric entry at Duna before realizing I forgot to add the Kerbal in the VAB, had to start the whole mission over.

But the weight shown in the SPH for the plane does indeed show the Kerbal.  As light as the glider is, the Kerbal weight was required to estimate COM and CL.