(Breaking Ground) Serious Help Needed for Getting R121 Turboshaft Engine to Work

[Mars-Bound Hokie]

The title's self-explanatory, but here are the details.

 

I recently acquired Breaking Ground and want to try the new R121 Turboshaft Engine. However, none of the tutorials I find seem to work out for me. Even my most successful attempts turned out to be failures.

 

• First attempt as it accelerates on the runway.

 

• After taking off at ~60 m/s, it rose for a bit then took a nosedive.
• Eventually, I crashed into the ocean.

 

When I installed the KAL-1000 controller and tried to follow the instructions from the tutorial videos, it seems like it made things WORSE - and, apparently, wrecked all subsequent attempts to correct this error. My second prototype for testing a propeller didn't help out either.

 

Below are the craft files of both of my failed attempts.

• https://mega.nz/file/TeAhwJwD#VQhNdFvCKejmi4nUusIjLx38ZOdLN_9mbQCVBWsGxzY
• https://mega.nz/file/yD40HTSa#sE2O_GRCPjaeAGSaIgDsw5YjQo_ET1Fcu8A014L21gw

 

Any ideas where I went wrong? Was it due to poor aerodynamic design or improperly setting up the propeller? How can I get the propeller to work?

• And do I really need the KAL-1000 controller? Sure, the second prototype failed, but initial performance without it seemed promising for the first thirty seconds.
  • WITH the controller, the plane was barely moving at all.
• Is there a written set of instructions I can reference - one that actually works?
  • And does these rules apply to electric propellers too?
• I'll test whatever answers are given and let you all know how they work out.

 

Thank you very much. If I can get this to work, then I can build USAF aircraft replicas and luxury vehicles for Laythe tourism.

Edited September 26, 2022 by Mars-Bound Hokie
Just realized that a gas-powered turbine with an air intake is useless on Eve and Duna.

[18Watt]

Screenshots showing the PAW (part action window) open for the engine, and one of the propeller blades, would be helpful.  There are too many possible things that could be going on to troubleshoot your issue without seeing the PAWs for the engine and propeller blades.

You do not need the KAL controller to make propellers work.  I never use KALs on propellers or engines.

If your first plane accelerated well down the runway, but crashed after takeoff, you are likely having aircraft design or aerodynamic problems.

Also, working with single propeller designs in KSP is extremely difficult.  The reason for this is the ridiculous amount of torque that the KSP engines produce.  The torque effects are extremely difficult to overcome.  One easy way to counter torque effects is to use two counter-rotating engines.

 

[Echo__3]

How you place the propellers, and their exact deployment angle are very important. 
I made this little tutorial to get players started with building and flying prop planes.

 

[18Watt]

Well, I am laughing right now at @Echo__3!  I was going to link his tutorial in this thread.  But he has already done that!

One of the most important points in @Echo__3's excellent video is to reduce rotor size as much as possible.  I can't emphasize that enough.  Reduce the rotor size!

A common question I hear is that in real life, there are lots of single-engine planes, and they work just fine!  Why is torque so difficult to work with in KSP?  There's a few answers to that:

• Rotor engines in KSP produce orders of magnitude more torque than their real-world counterparts.  
• Real-world aircraft have subtle aerodynamic elements designed to help counteract torque.
• In the real world, excess torque would result in excess RPM.  In KSP, the RPMs stop at 460, but the excess torque is still present.  Beyond 460 r.p.m. you are wasting fuel, AND generating excess torque which is doing you no good.

The answer is to control your torque.  You don't need as much torque as the engines can provide, so reduce their size and output in the SPH.  Also, monitor your RPMs.  If you are at or near 460 RPM, it's almost certain that you have excess torque which is doing you no good at all, and is in fact generating excess torque which will make a single-engine plane very difficult to control.

Start small and simple!  Make a simple plane work first, before jumping into supersonic propeller airplanes.  (Yes, that is possible in both KSP and in the real world too..).  

I'm considering writing a propeller tutorial.   However, the video by @Echo__3 is excellent, I don't think I can improve on that.

Edit:  BTW, @Echo__3's video can be found in the tutorials section here:

 

[Mars-Bound Hokie]

4 hours ago, 18Watt said:

Screenshots showing the PAW (part action window) open for the engine, and one of the propeller blades, would be helpful.  There are too many possible things that could be going on to troubleshoot your issue without seeing the PAWs for the engine and propeller blades.

And here you go. Below are the screenshots of my second attempt with the PAWs open for the engine and the propeller blades

 

 

 

4 hours ago, 18Watt said:

If your first plane accelerated well down the runway, but crashed after takeoff, you are likely having aircraft design or aerodynamic problems.

For this prototype, I may actually agree with you. However, when I mounted a three-blade engine on the back of my Baykar Bayraktar drone replica, I ran into worse problems. I know for sure it's not just poor aerodynamic design that's the problem since:

• This B.B. prototype didn't make it past 2 m/s on the runway, no matter which propeller direction I tried.
  • I didn't know if I needed to change it since it was a rear propeller.
    • If I can master this, then I can make a B-36 Peacemaker
• The engine was silent (as usual).
• Even if the plane was able to take off, it should have flown just fine since a different B.B. prototype of the same exact design EXCEPT FOR THE AFTERBURNER IN THE BACK was able to.

 

I tried reducing the motor size as you and @Echo__3 said, but that didn't seem to work.  Here are the screenshots I have of my latest attempt at this (and a true replica of its namesake)

• https://mega.nz/file/LOIXmB4I#_2fruOJo05Xv-CIWR7eOTE6Z3VdJSYXDkICJkQuTTtU - craft file if you want to try it out to see what went wrong.

 

• Apparently, reducing motor size didn't work out.

 

How do you recommend I get this baby airborne? If I can fix the problem with this prop, then I can make functional aircraft replicas that won't depend too heavily on electric charge.

[Echo__3]

@Mars-Bound Hokie, I worked with your UAV. You need to make sure when you place propeller parts, that the striped side is facing forward. I will use the absolute rotate tool to make sure that this is set correctly. This is so that the deployment angle will always be referencing the same point. The second thing when working with a pusher plane like this is to invert the direction of the motor (it's a setting under rotation direction) because the motor is facing backwards.

The aerodynamics and center of mass needed lots of adjustment. The center of mass would shift well behind the center of aerodynamic pressure as fuel is used. In the future, try to keep your wet and dry centers of mass in almost the exact same location. So, be aware of the differance between full and empty fuel load.

I switched out the propeller blades for fan blades but keep the motor size at 10% I added an action group (translate forward/backward) to control the deployment angle of the blades, but 22-23 degrees was working very well. I topped out over 120 m/s.

The tail needed work. Those little wing don't work well as elevators, but I tried to keep the same aesthetics.

https://1drv.ms/u/s!AgX4yLy61s3KqR5KrU9Bc5F0s78V?e=KFo6UV Here is my version of your craft

Edited September 27, 2022 by Echo__3

[18Watt]

1 hour ago, Echo__3 said:

@Mars-Bound Hokie, I worked with your UAV. You need to make sure when you place propeller parts, that the striped side is facing forward.

In your last example, your blades were facing the wrong way.

 

1 hour ago, Echo__3 said:

The second thing when working with a pusher plane like this is to invert the direction of the motor

This isn't always required, and not required at all in a single-engine design.  Just need to make sure the blades are facing the correct direction for the rotation of the motor.   This becomes critical when using twin-rotor designs.

1 hour ago, Echo__3 said:

The aerodynamics and center of mass needed lots of adjustment.

The COM (center of mass) and COL(center of lift) markers in the SPH should be taken with a large grain of salt.  Just because the markers look like they should in the SPH does not mean they are OK!!  You need to do some flight testing to determine if they are in the correct location.  That is a whole different subject.

1 hour ago, Echo__3 said:

In the future, try to keep your wet and dry centers of mass in almost the exact same location.

Amen brother!

1 hour ago, Echo__3 said:

I switched out the propeller blades for fan blades

Yes.  All the BG props and engines are overpowered,  For a light aircraft, you don't need the big stuff.

Keep working at it!  It's worth it!  I had never recovered a crew from Eve until I learned to use the BG props.  There's an insane amount of things you can do with props.

 

[Echo__3]

@18WattI do generally take the VAB and SPH indicators with a large grain of salt, especially since they do not factor drag. I spent some time working with and flying his craft. So, I know that it works well now.
And yes, I do understand how the rotor direction works. For simplicity, if I use the invert motor option for pushers. That way my blades and motors will be using the same clockwise/counterclockwise configuration. It can help when I'm copying and pasting parts around.

@Mars-Bound Hokie, in addition to understanding how to use the props, it is also important to have a good grasp on the fundamentals of airplane design. I have made a video tutorial based largely on the work of @keptin. Some things in the game have changed - like how drag is calculated - since his work was first published.

 

[Mars-Bound Hokie]

@Echo__3

Thank you so much for helping me with my problem, and especially for sending me a link with a modified version to work with.

 

Test run with your version

Spoiler

• Why do you have an oversized Mk. II probe core?
  • The regular sized probe core is mine for size comparison.
• Upon launch, the wings were flimsy and the tailfins fell off.

 

• After some modifications to the airframe and some strut connectors holding the tailfins, I managed to get this bird flying.

 

• Safe landing after about 11 minutes of flight time and 319 LF units to spare.

 

I will complain that your version is quite nose-heavy. However, apart from the range, its real-life counterpart didn't really brag impressive performance stats. At least I got this bird to fly and land in one piece.

• And I only built the replica for showing off to my friends since we were talking about it the day before (no, we're not Turkish).

 

Once I took it to the SPH, I opened the fuel tank PAWs so I can see how the weight was distributed. After that, I opened the engine and propeller PAWs and checked the main throttle action group.

• Apparently, the RPM limit may have been an inhibitor in my performance.
• I do have some questions regarding the motor size and output setting:
  • What made you decide 10%? Is that standard for all your propeller motors?
  • What are the absolute minimum and maximum motor size percentages I should heed if I expect the aircraft to fly?
    • Depending on the size of the aircraft (e.g. electric open-cockpit plane vs B-36 bomber), I'll have to adjust as necessary.

 

I then took your engine and blade adjustments under advisement and returned to my original B.B. craft file. Below you will find how I adjusted the Lf+Ox setup, the engine, and the blades.

• To be honest, I don't remember why I used 20% in the motor size and output instead of 10. I think it was because the aircraft was bigger and heavier than yours. 
• Either way, this design worked out great for me.

 

• My B.B. prototype with the new prop engine successfully flying over the KSC

 

• Perfect landing.

 

I'll need to get my MJ autopilot to work on keeping it level without sending it into an endless spiral first, but otherwise I'm impressed with the results. Thank you so much for your help.

 

@18Watt

1 hour ago, 18Watt said:

Yes.  All the BG props and engines are overpowered,  For a light aircraft, you don't need the big stuff.

Okay. Would the BG props and engines be fine for, let's say, a DC-3 - or something of medium-large size like a VC-118?

 

1 hour ago, 18Watt said:

I had never recovered a crew from Eve until I learned to use the BG props.  There's an insane amount of things you can do with props.

I haven't even put kerbals on Eve yet, so crew recovery missions will be a while. However, I should be able to send a drone in the meantime to collect science. Since Eve has no usable atmosphere for the air intakes, I'll have to use the electric motors - which is another bonus, since I should use solar panels and RTGs to charge it.

• I'll just need to test the drone on Kerbin first. After that, it's a matter of sending the drone to Eve's surface without blowing up.
• A couple of questions:
  • For an unmanned science drone on Eve, should I go with the ducted fan blades or the regular propeller blades? 
    • I plan to carry:
      • Thermometer
      • Atmospheric GCMS
      • (Maybe) a scanning arm
      • Seismic accelerometer
      • Gravioli detector
      • Barometer
      • Surface scanning module
  • Would this work on Duna too?

 

Again, thank you all so much for your help. Can't wait to fly old-school.

[Echo__3]

@Mars-Bound HokieIt looks like the craft didn't transfer well from my save to yours. I didn't resize any parts or even do anything with the probe core. So here are the basics of what I did.

I changed out your rear wings and control surfaces because they were too small.
I used RCS Build Aid to balance your center of mass so that it wouldn't shift as fuel is used. This means that I added some mass to the nose of the craft and moved all of the fuel to the rear.
The main wings were adjusted to increase their angle of incidence for better lift and give them a dihedral angle for stability.
I repositioned your rear landing gear. I attached them to the fuselage instead of the wing. This let me adjust the wings and gear separately and make sure the gear is placed perfectly straight.

You used I-beams for your tail booms. I didn't change this, but in general I prefer to use the radially attached air intakes instead because they are a lot lighter. Using the I-beams shifts the center of mass further back and make balancing the fuel harder.

As far as the motor size goes, reducing the size in the hanger also decreases its mass. In testing, I found that 10% was just enough to keep the rotors spinning at full RPMs. So, any larger would just have been a waste.

7 hours ago, Mars-Bound Hokie said:

I haven't even put kerbals on Eve yet, so crew recovery missions will be a while. However, I should be able to send a drone in the meantime to collect science. Since Eve has no usable atmosphere for the air intakes, I'll have to use the electric motors - which is another bonus, since I should use solar panels and RTGs to charge it.

Eve is closer to Kerbol, so solar panels work even better there than at Kerbin. The fan blades in general just seem to work better than the regular propeller blades even though the produce more drag. You will not need as many blades to fly as on Kerbin (or to spin the rotors as fast), but you will need more motor torque because of how thick the atmosphere is.

7 hours ago, Mars-Bound Hokie said:

Would this work on Duna too?

Prop planes can work on Duna, but barely. They only are flyable in the very low atmosphere. A nice thing though, is once the plane is on a suborbital trajectory, you won't need any other parts to assist in landing.

Here is a plane I made for Duna. I've also made an Ingenuity inspired craft as well.

 

[18Watt]

15 hours ago, Mars-Bound Hokie said:

Okay. Would the BG props and engines be fine for, let's say, a DC-3 - or something of medium-large size like a VC-118?

It's very hard to compare real world engines to other real world engines, and even more difficult to compare KSP engines to real world engines.   For planes, we are really only concerned about thrust produced.  However, with electric motors or piston or turboshaft engines, we have no way of directly measuring thrust.  All we can really measure directly is the torque output, and from that determine how much power the engine is producing.  But torque and power do not produce thrust.   A lot of 'educated guesses' are involved in estimating thrust produced from propeller airplanes.  

Keep in mind, the max speed of a DC-3 was about 105 m/s.  The DC-6 could cruise at 140 m/s at altitude, and probably (guessing) was able to safely hit 150-160 m/s before parts started getting blown off.

The KSP turboshaft engines probably produce about 4 times the power you would need to fly a DC3.  I'm not familiar with the VC-118, are you referring to the military designation for the DC-6?  If so, probably the same thing.  That's a bigger plane, but uses 4 engines.  Not sure about the VC-118, but if it's the DC-6 then I'm pretty sure all the production DC-6's had water injection available.  

Instead of starting with a nerfed engine(s), here's another approach you could take:  Put the full size engine on your plane.  Tie torque to the main throttle- so you are controlling torque.  Instead of going full throttle during testing (which is what we all do in KSP ), start out at say 10-25% throttle.  You can play around with throttle settings to see how much torque you really need.  Once you figure that out, you can go back to the SPH and scale back your engines.  

Or just keep flying the plane at a reduced torque (throttle) setting.

For unmanned drones on Eve, the BG props work fantastically well.  For the size of drone you have in mind, I would use the smallest electric rotor.  I would consider using a twin-rotor counter-rotating design so the torque cancels out.  And I suggest using the smallest ducted fan blades.  The small ducted fan blades will be more than adequate, and the shorter blades make it easier to keep them from hitting the ground.

As near as I can tell, the ducts that you can put around the ducted fans are purely cosmetic- they do not affect the performance of the blades at all.  Maybe they would help keep Kerbals from walking into the spinning blades, but you can always just hire more Kerbals if that happens..  Anyway, you don't need to use the ducts themselves, that's a purely cosmetic option.

If your Eve plane uses variable-pitch propeller blades (which I recommend if you can figure that out..) then you don't need very good brakes on your plane.  With the rotors turning, if you set the prop pitch to zero the plane will stop almost instantly.

One additional suggestion for building a drone for Eve, or any type of surface vehicle-  Whatever size landing gear looks like it will work, use the next bigger size.  You'll regret not using beefier landing gear on Eve if your wheels keep breaking..

[Mars-Bound Hokie]

@Echo__3

19 hours ago, Echo__3 said:

You used I-beams for your tail booms.

Like I said earlier, I only made that plane for show. Apart from maybe posting on KerbalX, I have no further uses for the B.B.

 

19 hours ago, Echo__3 said:

Eve is closer to Kerbol, so solar panels work even better there than at Kerbin. The fan blades in general just seem to work better than the regular propeller blades even though the produce more drag. You will not need as many blades to fly as on Kerbin (or to spin the rotors as fast), but you will need more motor torque because of how thick the atmosphere is.

After watching Matt Lowne's video on a science plane to Eve (see video), I decided to give it a try myself with some modifications of my own. More specifically, my version is:

• Completely unmanned
  • Right now, Eve's surface is a one-way trip. I'd rather not send anybody there until I've established that two-way travel is possible.
• No goo or materials
  • Which is related to the first major difference in my design.
• More energy storage

 

When it came to making the twin engines, I found that if I make one good forward-facing prop engine in the back as usual and then added the engine+blade combo symmetrically in the front (as Matt did here), the engines work out great. Trying to change the direction and blade orientation of the two engines individually didn't work.

 

After confirming that my design works on Kerbin (despite being nose-heavy), I teleported it to Eve's surface and waited for a signal. Here are the screenshots of my Eve test run.

• Almost looks like I'm going faster on Eve than I am on Kerbin.

 

• Not bad.
• Still have to constantly pitch up to keep it level, not to mention it just loves to keep rolling 
  • And the roll hold is completely useless if not treasonous.
• Took a total nosedive when the signal broke, signaling the craft's doom.
  • I promise you that my career save will have better coverage once this drone is finalized.

 

• My first Eve drone prototype in the SPH
• The front tanks are empty while the rear one is full.
  • I fear that, if I fill up the front tanks, the craft will get even more nose-heavy.

 

20 hours ago, Echo__3 said:

Prop planes can work on Duna, but barely. They only are flyable in the very low atmosphere.

Well, if it's that risky, then I probably won't be using aerial drones on Duna often if at all. I already have the Dirtblood and a quite popular mobile base, so I'm pretty much all set in exploring Duna. Thanks to you, though, I would have general guidelines for making a VTOL drone when it comes to exploring the canyons.

 

 

@18Watt

13 hours ago, 18Watt said:

Keep in mind, the max speed of a DC-3 was about 105 m/s.  The DC-6 could cruise at 140 m/s at altitude, and probably (guessing) was able to safely hit 150-160 m/s before parts started getting blown off.

I checked the Wikipedia pages for both planes, and they're not exactly impressive stats. At least they'd be good places to start when making larger and/or more practical aircraft.

 

13 hours ago, 18Watt said:

I'm not familiar with the VC-118, are you referring to the military designation for the DC-6?  If so, probably the same thing.  That's a bigger plane, but uses 4 engines.

Holy crap, you're right. At the time I posted on here, I had no idea that the VC-118 was the military counterpart for the DC-6. All I knew was that the VC-118 was the second Air Force One. Now I know what to go for when making that replica.

 

13 hours ago, 18Watt said:

For unmanned drones on Eve, the BG props work fantastically well.  For the size of drone you have in mind, I would use the smallest electric rotor.  I would consider using a twin-rotor counter-rotating design so the torque cancels out.

If you scroll up on this post, you'll find that I did make a twin-engine drone. I didn't use the small electric rotors since I was unsure on how much thrust I'll need due to Eve's increased gravity (and Matt's recommendation, but I think it was mainly because his model weighed more). Maybe I could still fly just fine with the small rotors like you said.

• Also, like I said earlier, when I tried making counter-rotating individual rotors, the plane couldn't take off. I just followed Matt's instructions, and they seemed to work out fine for me during testing.

 

13 hours ago, 18Watt said:

Whatever size landing gear looks like it will work, use the next bigger size.  You'll regret not using beefier landing gear on Eve if your wheels keep breaking..

Thank God for Alt+F12 and Sandbox Mode for test runs, both on Kerbin and Eve. I'll just need to teleport some more relays.

[Echo__3]

2 hours ago, Mars-Bound Hokie said:

Still have to constantly pitch up to keep it level, not to mention it just loves to keep rolling

Your Center of mass is very far forward compared to your center of aerodynamic pressure. You could use straight wings instead of swept wings to move the center of pressure forward. This will help the plane fly more level.

Your roll issue is caused by having both of your rotors spinning in the same direction. In the SPH, click on one of the rotors and remove it from symmetry, then change the direction from clockwise. Then you also need to change the propellers on that rotor to counterclockwise. With two rotors spinning in opposite directions, this should cancel out their torque.

[18Watt]

Just wanted to show you a few examples of unmanned propeller planes for use on eve.  In all cases, I'm using two of the smallest electric rotors, each having 6 of the smallest ducted fan blades.

Example 1:

Spoiler

I intentionally made this one clunky and un-aerodynamic.  It should be easy to build something much more efficient than this one.  I included pretty much all the science experiments, although without a scientist on board the Materials Bay and Goo canister are kind of useless.

I got it up to 5 tons by adding a couple of full ore tanks.  Note that I have sized the rotors to 80% of their max torque.

Sitting on Eve, ready to go.

Hitting 110 m/s in level flight.

Here's another, more optimized model:

Spoiler

This one uses girders for a frame, and everything is encased in a fairing.  Still has all the science stuff, except for the Materials Bay and Goo.  Small rotors are set to 100% this time.

On Eve.  I need to disable the Comm Net..

In flight I hit speeds of 180+ m/s.  I'm using 94% of the available torque.  (Rotors are 100% this time).

Landed.  These planes all fly just fine at 35 m/s or less on Eve.  Landing is easy.  Note I'm using the larger (2-wheeled) landing gear.

And here's another, possibly more practical version:

Spoiler

This one doesn't use fairings.  I have 3 1.25m cargo bays to store equipment in.  I have most of the science stuff in the middle bay, mounted on a structural panel.  Both rotors are set to 100% torque, with 6 blades small ducted fan blades each.

This one hits 200+ m/s no problem.  I'm at 96% torque.  In good sunlight, the two big solar panels are plenty to keep the batteries charged.

Like the other two examples, this one also flies and lands fine at 35 m/s.

@Mars-Bound Hokie, your P-47 style plane is really cool looking.  However, there's a few reasons to go with a narrower design.

• Launching a plane with a big wingspan is very difficult.  Keep in mind, ya gotta get it to Eve somehow..
• Getting anything from Eve orbit to the surface is also difficult.  Everything will need to be protected by a heat shield, and possibly encased in a fairing too.  Wide airplanes are difficult to protect for an Eve atmospheric entry.

Eve's atmosphere is so thick that you need far less wing area, compared to what the same plane would need on Kerbin.  Even just a MK2 fuselage with no wings will fly fine on Eve.  

 

[Mars-Bound Hokie]

18 hours ago, Echo__3 said:

Your roll issue is caused by having both of your rotors spinning in the same direction. In the SPH, click on one of the rotors and remove it from symmetry, then change the direction from clockwise. Then you also need to change the propellers on that rotor to counterclockwise. With two rotors spinning in opposite directions, this should cancel out their torque.

You know what happened when I did that? My drone wasn't nearly as nose-heavy and it started to actually stay straight and level.

• Actually, it's still a bit nose-heavy when gliding. Nothing a little throttle won't fix, though.
• I didn't adjust the wing structure because I wanted to test ONE ADJUSTMENT AT A TIME. And since the engine modification alone worked out great so far, I decided to keep the wings as they are.
  • If I need to modify the airframe for Eve operation/transport, I will.

 

• It was dark when I took off. With 18,015 units of electric charge ready, I think I was okay.

 

• Once I got the drone to a safe altitude (I did 5 km) and kept it level, I just left it alone.
• It may have descended approx. 1000 m before rising back up on its own, but otherwise not bad.
  • That's why I took it so high.
• Its cruising velocity averaged at 120 m/s.

 

• Mid-flight, I realized that I was wasting electricity by cruising full throttle.
  • I reduced speed to 1/2 to 1/3 throttle, and the airspeed stayed the same while the plane still maintained a (somewhat) level flight without my help. 
• Note-to-self: when you get your flight path set, reduce throttle.

 

• Those bottom lights are more powerful than I thought. They really came in handy when landing on a hilly grassland peninsula and my drone was nearing 5,000 units left.
• After minutes of some bouncing touch-and-gos (unintended), I brought the plane to a complete stop.

 

• It took me almost 1.25 days for the plane to be recharged to maximum capacity.
  • It probably would have gone a lot faster if I remembered to extend the tailfin panels. In my defense, I was too chicken to press the button since the last time I hit it was when I meant to turn on Kerbnet mid-flight and the panels flew off.
• After that, I took off up the east hill and started flying towards the sunrise.

 

• Check the surface info tab and you'll see the general area where I had to make a pitstop.
  • If I took off early in the morning instead of the middle of the night, I would have made it a lot farther.

 

• For the next few hours, I'll be flying without risk of a battery drainage.

 

Since it was getting boring watching a plane fly with pretty much no problems over the ocean, I decided to entertain myself with some math. Specifically, how fast I would have to go at minimum to keep up with the sun if I was to maximize my solar charge time. Below are the velocities that the planets revolve around their respective axes in m/s.

• In addition, since the sun rises in the east and sets in the west, I'll have to fly RETROGRADE (west) to stay with the sun.

• KERBIN: There is no way I can reach that velocity with that drone, so I'll have to time my takeoff to have as much sun time as possible. More specifically, I'll need to take off shortly before sunrise so that I can get a head start on the sun and have plenty of charge left over by the time the solar panels start charging.
  • Then again, why would I need to use that drone? If I need to collect data on Kerbin, I have a whole collection of jets that can do the job for way less than a sixth of the time and half the money.
• EVE: If I can match that velocity at a safe altitude without losing control (due to going too slow) on Eve, then I can practically keep my drone airborne FOREVER.

 

@18Watt, although I'll be paying attention to Matt's video on how to pack and move my current drone prototype, I'll keep your designs in mind in case bringing it to Eve is not possible. Thank you.

• FYI, the Republic P-47 Thunderbolt is actually a single-engine fighter. Are you actually referring to the P-38 Lightning (not to be confused for the F-82 Twin Mustang)?
  • My drone's stats are not as impressive as the P-38's, but at least I got a general structural design going for when I make that replica.