Folding Fido (a folding rover) [pic heavy]

[Brotoro]

Replacing some vanished threads:

(For the person who requested the .craft file, that link has been added.)

Folding Fido

In my recently posted "Driving Duna" adventure (where I drove a rover all the way around Duna), one person commented on my photo of the Fido rover sitting on top of its rocket. He was rather displeased that Kerbal Space Program lets you get away with ignoring aerodynamics, and just slapping MOAR BOOSTERS onto something (like my rover with its big "heat shield" plate) and pushing it into space. For the record, he was not complaining about my mission in particular, just in the lack of proper aerodynamics in KSP. The offending image is shown below.

My first thought was, "What must this guy think of the monstrosities used to loft those huge rovers with the giant wheels?" My second thought was, "Don't I at least get points for bothering to include a "heat shield" in anticipation of the time when we will all face the perils of deadly reentry heat?" My belated third thought was, "Well...he has a point..... so how do we go about fixing it?" I wanted the wide wheelbase for the Fido so that it would be very stable and safe for kerbals to drive at high speeds across alien landscapes (because...you KNOW they are going to). So how could I get my wide rover into a smaller living space? By folding it! NASA does this sort of thing all the time. But how to unfold a folded rover? I used the cool Damned Robotics mod. Specifically, the "door hinge" part from that mod pack.

Below is my folded Fido rover with its "heat shield," sky crane lander, and token nose cone. I didn't actually make an aerodynamic shroud for the thing (you can just picture that running from the base of the nose cone to the heat shield. And you can picture the heat shield as nice and round with an ablative coating (instead of something I kludged together from plate structural parts).

First lets get rid of the nose cone. A decoupler and two sepatrons take care of that. You can picture the aerodynamic shroud that you were picturing splitting in half and blowing away, too (you didn't know this thread would involve all this reader participation, did you?). One of the sepatrons is canted sideways by one tick to make sure the nose cone gets out of the way of the rest of the vehicle (it crashed about 500 meters away).

The animated GIF below shows the two sides of the Fido unfolding. I have this action of the hinges controlled by the 0 key (Damned Robotics's little control panel lets you specify what keys to use for a hinge or group of hinges in the VAB). The rover actually appears on the launch pad unfolded, so I needed to fold it up before showing it off or launching it (using the 7 and 9 keys).

Below, four more hinges are called into action with the 8 key to swing out the wheel mounting plates. You must press the key several times for full deployment, since the hinge can be positioned at intermediate positions.

Below is the Folding Fido rover with its wheels fully deployed. The wide wheelbase of my dreams is realized from a more compact package!

You may have noticed that the exhaust blast from the sky crane's engines would impinge on the rover when it is fully deployed...this is true. So the sides of the rover can only be partly deployed under the operating sky crane. Below you can see the sky crane hovering the Fido over the KSC during a test flight. Sure, you could mount the sky crane engines further out to prevent this, but I wanted a sky crane that would fit inside the imaginary aerodynamic shroud, and which would also be protected by the heat shield during reentry. So I'll live with this partial-deployment limitation.

In the next picture, I've dropped the heat shield so I can set the Fido down with the sky crane. I also deployed the wheel mounting end plates fully before dropping the heat shield.

After the Fido is set down in its partially-deployed condition, and the sky crane has flown off, the side pieces of the Fido can be deployed the rest of the way. Note that you do not have to deploy the sides completely: If you are going to be driving over some rough terrain, you can dial in a higher ground clearance (at the expense of a little narrower wheelbase).

Below are two pictures of the fully-unfolded Folding Fido. I was worried that the hinges might not be very strong and the whole thing would just flop to the ground, but the hinges are quite sturdy. You can see them flexing a little when the rover hits bumps, but I was pleased with how well they held the rover in its shape. The Fido is very stable and corners well at speeds of 23 m/s (with its ASAS on). Hmmm...I should have deployed the ladder (it's in the nose of the capsule). And I see that I forgot to remove two of the solar panels from the center plate on the right side (where they would be susceptible to damage by the engine blast...I removed the two on the left side). The Fido has four RTGs and two of the Z-500 battery banks, so it can drive some distance even in the dark (but would need to stop and rest occasionally). The Fido has a couple strategically placed small I-beam pieces on the underside to protect the more fragile parts if the rover gets bonked on the bottom.

Below we see the Folding Fido payload on top of a unnecessarily powerful booster that could probably send it most anywhere in the Kerbin solar system with its nuclear transfer stage. I've already folded up the rover so you can picture the nice aerodynamic shroud enclosing it. Go ahead. Picture it. Smooth. Nice curves. Oh yeah.

For those of you who couldn't bother to play along, below is the "5,000 hours in MS Paint" version.

I haven't sent the Folding Fido on a mission to another celestial body yet, but I did try out reentering it into Kerbin's

atmosphere. Below is the retro burn.

Here are two images of the reentry. All parts of the Fido and its sky crane lander are protected by the heat shield (as long as you keep the heat shield pointed in the retrograde direction). You don't get the blazing white-hotness of an Eve entry, but the heat shield is working well. You can imagine the smell of charred ablative material now if you are still playing along.

Below: dropping the heat shield. I hope everybody at the KSC in undercover, because a toasty-warm present is coming their way.

This is the point where I quickly deploy the side pieces to their partially-deployed angle, and swing the end wheel plates out all the way in preparation for landing.

The animated GIF shows the successful sky crane maneuver, followed by full deployment of the Fido.

I also included two parachutes on the Fido so that it could use the alternate landing sequence below on a body with a sufficiently thick atmosphere (Kerbin, Eve, Laythe... or Jool if you are nuts). In this alternate landing sequence, I separated the sky crane soon after jettisoning the heat shield...

...then popped out the two chutes and began full deployment of the wheels (in progress in the picture below).

Below, the Fido is coming down at about 7 m/s. It landed undamaged...but I think maybe two more parachutes (placed on the two plates attached to the central core) would be better.

Now I just need Kerbal Space Program to include the feature that lets me make any size and shape aerodynamic shroud, and I'll be all set. And a prettier heat shield, of course.

Update

I landed the Folding Fido on Minmus to test it out. Its sky crane is ridiculously overpowered for Minmus... when I separated it after landing the rover, the sky crane spent many minutes thrusting at low power, very slowly tumbling, and it couldn't seem to decide if it wanted to end up in a high orbit around Kerbin, or escape into Kerbol orbit. In the end, it escaped. The Fido worked fine...and I could make it hop upward quite a ways just my partially folding in its wheels.

I made some modifications to the Fido to make the sky crane/heat shield/nose cone arrangement a little more compact and a bit lighter. Below is the modified version folded and unfolded. I also have the .craft file for the payload posted. It requires the Damed Robotics Door Hinge part, and that requires that the MechJeb dll file be installed. The Fido has the hinges set to use the 7 key to fold in the wheel end plates (fold these in until the wheels are close together...it will be a greater than 90 degree fold), and the 8 key to unfold the wheel end plates. The sides of the Fido are folded down with the 9 key (fold them in 90 degrees), and unfolded with the 0 key. You may not want to unfold the sides completely if you want better ground clearance (especially if you want to drive using physical time warp...the hinged Fido deforms downward MUCH more under high time warp than the unhinged Fido KE it's based on). Using 4x time warp will bottom out the Fido even if you have a lot of ground clearance set.

I made the heat shield less dish-shaped. It still has the same coverage, but it lets me mount the Fido closer to the heat shield. Below is a reentry from 1000 km for better reentry effects.

But the most important change was rotating the sky crane 90 degrees and repositioning the rear RTGs... Now the wheels can be fully deployed for landing under the sky crane.

Folding Fido .Craft File

Another Update

I modified the sky crane some more, making it more compact. The Fido rover has been modified to have two capsules in a "push-me-pull-you" configuration.

The sky crane has less fuel than before, but still sufficient to return the Fido from Kerbin orbit, so it can handle a landing on several other bodies.

Below, the sky crane deposits the Fido near the VAB and then heads off to crash. It's definitely a good idea to fold the sides of the Fido down a couple notches before landing since this gives it more ground clearance to survive a bounce if you drop it from a little higher than you should.

Here is the .craft file for the newest update. Remember that it requires the Damned Robotics Door Hinge part.

[Procyon]

very nice concept. maybe they will make movable parts like that for the stock game.

[wooaa]

how fast can you get the rover

[Brotoro]

how fast can you get the rover

I haven't tried this version of the rover as extensively as the non-folding version that I used to drive around Duna (see this thread). The non-folding version cruises over flat ground at between 20 and 30 m/s... but it can reach speeds over 60 m/s going downhill (which I believe is the blowout speed for those wheels).

The folding version is basically the same configuration, so I would expect similar speeds. BUT you must be more careful with the folding version because if you hit bumpy ground, it will flex more than the non-folding version, so you could bottom out and cause damage. Leaving the sides partially folded helps prevent this.

Also, the non-folding version of the rover can be used a 4x physical time warp over sufficiently level ground. But the (I presume bug) that causes rovers to apparently weigh more at time warps will press the more-flexible folding frame downward much more, and can result in damage when it bottoms out. Again, only partially deploying the sides can help, but 4x time warp is too much for this rover even then. So while it may be able to do about the same speeds as the non-folding version, you do not have the option of running it at the highest time warp (so your drive will be longer).

[reptile2001]

I thoroughly enjoyed reading through this. Awesome rover and delivery system as well!

[ThatBum]

Might be able to make an in game fairing with the KW rocketry fairings, or maybe Fairing Factory. I think I'll give it a go when I get back to the gaming computer tomorrow.

[Brotoro]

Fairing Factory

A couple people (such as ThatBum above) have suggested that I try out Fairing Factory to make an aerodynamic shroud to cover my Folding Fido... so I gave it a try. The interface of the Web page for making the fairings was pretty straightforward, but it took me a couple iterations to get the fairing the correct size (and even then it wasn't perfect because I had to mount it a little lower than I intended, since the base piece had to go BELOW the coupler for the second stage...otherwise it produces no thrust; I found this out the embarrassing hard way). Also, the fairing is a bit larger than necessary (and covers the heat shield that is also a bit larger than necessary... but that was lucky since everything was able to still fit after I needed to position the fairing a bit lower.

There weren't any instructions available (since the instructions were just a link to a KSP Forum thread that had evaporated in the recent Great Forum Wipeout). I dropped the .dll file and parts folders for the fairing in the appropriate KSP folders and the parts showed up in my Structural tab... but couldn't figure out how to mount the fairings on the rocket. After several stumbles, I finally noticed the 2-meter base piece that was also now in with the Structural parts, and I was able to connect everything.

Below is the rocket on the launch pad as it first appears. You'll notice that the Fido's wheels (which have not been folded yet) stick out through the thankfully insubstantial fairing. I used the 7 and 9 keys to fold up the wheels. I could zoom in a get a clipped view inside the fairing to see that the wheels were folded in the correct position.

Below is a picture of the liftoff. The rocket looks a lot like a Rocket Propelled Grenade...but it DOES look more aerodynamic. I guess I should have added nose cones to the tops of the boosters instead of leaving them embarrassingly flat. Of course, the fairing is there for aesthetic reasons only; it does not reduce drag in the current version of the program (and it does add weight). But it's there to be pretty. Admire it. Go ahead and complement it on its looks; fairings like to have their self confidence bolstered, too, you know.

The rocket I'm using is my Reusable Rocket that has all of its parts recovered at the KSC. Below we see the side boosters dropping off at 18,000 meters, and then the sustainer can start a belated gravity turn. This is not an efficient trajectory, but fuel is cheap compared to rocket hardware. (Yes, I know those boosters will despawn before they land, but if you were to follow them down they do indeed land safely on KSC property).

Once the initial turnover was complete and the rocket was above most of the atmosphere (at around 45,000 meters), I jettisoned the fairing. As you can see in the image sequence below, the separation leaves a bit to be desired. The fairing halves don't blow away far enough, and they go scraping down the side of the rocket. Luckily the interaction with these ghostly parts has no negative effect on the rocket (other than maybe sending a chill down its spine). The departure of the fairing also reveals the upper stage that will boost the Fido to the Mün, which was covered by the lower part of the fairing.

Below, the rocket has achieved a stable 120-km orbit and the sustainer separates. (The sustainer will go on to retro fire and return to a landing at the KSC; this mission has left plenty of fuel in the sustainer's tanks that it will be able to do a landing on its rocket flame and not need its parachutes.) Meanwhile, the Poodle engine of the upper stage will push the Fido off to the Mün.

Here we see the upper stage firing again to put the Fido into Münar orbit ("Münar orbit insertion? Moi?"). I did the burn somewhat early just for the photo op of having Kerbin in the background. I presume NASA does not necessarily time their orbital burns specifically to allow for good pictures.

Because the far side of the Mün was illuminated, I decided to land near the mouth of the big canyon that juts off the large Mare on that side. The upper stage engine was fired one last time to do the initial deorbit burn (so that it would crash), and then the Fido and sky crane separated. Below we see the Fido coming in along the canyon. The heat shield (useless over the airless Mün) has been jettisoned and can be seen heading off for its own impact.

The next picture shows the Fido just after touchdown as the separated sky crane heads back up under very low thrust.

And the Fido is off to explore the canyon! Driving is certainly easier on the Mün than on Minmus. I was surprised at how hilly the terrain was outside the entrance of the canyon (I couldn't even see the mouth of the canyon from the landing site because of intervening ridges). Note that this version of the Folding Fido has two single-kerbal capsules, but this was an unkerballed mission.

After I was driving along for a few minutes, I heard the (rather obnoxious) noise of the little 24-77 engines of the sky crane. Uh oh...it was coming back in for impact, and was close enough to hear (not that you should be able to hear it on the airless Mün... but there's no uses screaming about that, since nobody will hear that in Space either). I zoomed out and panned around, and I was able to snap the picture below of the sky crane impacting over half a kilometer away. The Fido is the little thing in the center of the picture.

I was generally driving along at about 22 m/s... slower uphill, faster downhill. I jacked up the chassis a little so that I could safely use 2x time warp while driving. Note that you aren't offered the option of using physical time warp on the Mün as you are on Kerbin or Eve, but you can force physical time warp by pressing the Alt and > keys. After several minutes of driving, I topped the last ridge and got a clear view of the canyon. I was a bit disappointed that I didn't see Scott Manley's Mün truck coming along hauling his moonbase structures to their new location...but you can't have everything.

Brotoro's KSP Web Pages.

[ThatBum]

Awesome. That is indeed quite a thing, I feel it would make a good Kethane miner if the capsules were replaced with mining equipment.

The fairings can be separated better with the thrust from sepratrons, as demonstrated in katateochi's

. It seems they have zero ejection force, which is a bit of shame. KW rocketry's fairings eject pretty vigorously, as well as the NovaPunch ones.

And it does look like an RPG. That made me laugh.

Edit: Try it with Ferram. Hah, that will be nuts.

Edited April 21, 2013 by ThatBum

[apoch1999]

so have you tried the plating as a heat shield trick with the deadly reentry mod? i might go do that..i have it installed...wondering if they work ....

[Brotoro]

so have you tried the plating as a heat shield trick with the deadly reentry mod? i might go do that..i have it installed...wondering if they work ....

No, I don't have deadly reentry installed. I just include the plate heat shields as a placeholder for a real heatshield until those become available and necessary. For now I live happily without reentry heat...I expect it will greatly limit our designs when it is implemented.

But I would be interested in seeing the results of your experiment.

[ComradeGoat]

That's incredibly impressive! I hope we get stock hinges.

[apoch1999]

No, I don't have deadly reentry installed. I just include the plate heat shields as a placeholder for a real heatshield until those become available and necessary. For now I live happily without reentry heat...I expect it will greatly limit our designs when it is implemented.

But I would be interested in seeing the results of your experiment.

its not really that bad..have to make sure your oriented correctly or retro burning through the effect to survive without one though...ill post it as soon as i get pics

[GeorgeG]

Looks like a big egglofter.....

- George Gassaway

[Werwolf]

Seeing stuff like this makes all my stuff seem crappy and dingy. Lol, awesome work dude. I want to download it so bad, but I have this.... thing.... where I won't allow myself to use other people's creations. It's absolutely fantastic, though, very impressive! Love your threads, read the one of your trip around Duna. Good stuff man, keep it coming.

[Spektyr]

Probably a stupid question, but how do you launch a capsule built for Kerbals without a Kerbal in it? I've seen people talking about launching empty fuel tanks too, how is that done?

[Brotoro]

Probably a stupid question, but how do you launch a capsule built for Kerbals without a Kerbal in it? I've seen people talking about launching empty fuel tanks too, how is that done?

When you assemble the launch vehicle, you start with one of the probe bodies (not one of the kerballed capsules). Then any capsules you add will not have kerbals in them when you put the rocket on the pad.

For empty fuel tanks, possibly they are using a mod, or possibly they just fire the rocket's engines on the launch pad to use up fuel (and move the fuel out of the tanks they want to be empty and into the tanks it got drained from).

[Procyon]

might have to give that mod a try, just the hinges

[Brotoro]

The ability to fold up a rover is cool... But now that I've been driving one around a lot on Laythe, I wished I would have just sent an non-folding version (like I used on Duna and Eve). The hinges have begun to act a bit strange over time. When I came back to the game after a save one day, the hinges were all a bit off in their connections, and not just in the direction the hinges move... The side parts of the rover are now on a bit crooked, so it's a little duck-footed or pigeon-toed (depending on the direction I drive it). It still works, but this small angle makes it more difficult to control going down hill.

Also, the weakness of the hinges makes running at hugh physics warp impossible, since that phantom extra mass that the rover gains at physics warp causes it to bottom out... So driving long distances is tedious.

It would be nice if my kerbals on EVA could just add some struts to the thing. The again, a lot of my other recent problems (wobbly vehicles assembled in orbit) could also be solved if the devs gave our kerbals the ability to add struts while on EVA.

[Catullus]

You could try quantum struts, but I suspect that adding rigidity to something that's loading slightly crooked would result in fireworks.

[Brotoro]

I don't "get" Quantum struts. If these kerbals had some force beam technology, I figure they'd be using it all over. So the concept looks out of place.

[Spektyr]

When you assemble the launch vehicle, you start with one of the probe bodies (not one of the kerballed capsules). Then any capsules you add will not have kerbals in them when you put the rocket on the pad.

For empty fuel tanks, possibly they are using a mod, or possibly they just fire the rocket's engines on the launch pad to use up fuel (and move the fuel out of the tanks they want to be empty and into the tanks it got drained from).

Thanks! I've been wanting the better torque of capsules but without the responsibility of bringing Kerbals back. Plus if I build something with a capsule in it and leave it on a planet somewhere for years, a later manned expedition can put it to use if need be.