How to accidentally build airplane.

[Sharpy]

I was trying to make another version of the rover for Kerbal-Dakar.

Notice the jet engine. It's angled in such a way as to push the rover firmly to the ground. Notice how after closing the ramp, the nose forms a downwards edge meant to push the rover nose down, towards the ground. Notice how I didn't use a single aero part. Just Buffalo rover connector, ramp (for cabin) and small tank (with battery built in), two random structural panels from LLL, which for some reason have 130m/s impact resistance which was the sole reason I picked them, trucky wheels (again very high impact resistance), a subsonic jet engine chosen for CoM being farthest from the actual engine, radial intakes, a tweakscaled small reaction wheel, and a single stock parachute to stop at the flag faster.

 

It ran great through the plains. 140m/s and not a twitch, responding to turning neatly. Then it drove up the hill, expectably jumped when the incline ended... and didn't land back down.

Using the RW I turned it, and it responded. I made a circle over the grasslands, then headed back towards KSP, still gaining altitude. I maneuvered some, made a barrel roll, an alieron roll, a loop, then deployed the chute some 5km over VAB, switched the engine off and tried to land on the roof. Missed it by some 10m, landed unharmed. The first two pics are from that landing.

 

I did everything by the book to build a rover that firmly sticks to the ground. And I couldn't have failed more.

If someone says building airplanes in KSP is difficult, direct them to this thread.

 

Edited January 1, 2017 by Sharpy

[Whisky Tango Foxtrot]

I think that the bottom of your rover is acting as a lifting surface, and the angle of your jet engine is ensuring that there's a good amount of airflow over that surface.

[Scotius]

Welp, you've made a flying car - a Holy Grail of futurists and geeks around the world Congratulations!

[StahnAileron]

I'm actually interested in seeing what the aero-forces on that looked like. Should've hit F12! At least we know body-lift can actually be practical. (I usually have to be going at absurd speeds or horrendous AoA to see the light-blue body lift forces when I'm testing craft.)

[Sharpy]

18 minutes ago, Whisky Tango Foxtrot said:

I think that the bottom of your rover is acting as a lifting surface, and the angle of your jet engine is ensuring that there's a good amount of airflow over that surface.

In one hand - yes, that's probably the reason. On the other hand - nothing is marked 'lifting surface', I didn't do any planning of placing CoM vs CoL, there are no control surfaces, no stabilizing fins, that thing was built with a definite purpose of being NOT AIRPLANE. It's not a glitch though - it's just a weird accident that parts meant to be "not airplane" when placed flat on the ground become "very airplane" when turned 45 degrees. And it flies. And it's controllable. The point is that whoever thinks airplanes in KSP require special skill is plain wrong - airplanes in KSP can happen by accident!

9 minutes ago, StahnAileron said:

I'm actually interested in seeing what the aero-forces on that looked like. Should've hit F12! At least we know body-lift can actually be practical. (I usually have to be going at absurd speeds or horrendous AoA to see the light-blue body lift forces when I'm testing craft.)

Good point. Will do once I catch some zzz.

[Carl]

Quote

airplanes in KSP can happen by accident!

Oh accidental aeroplanes are easy. Deliberate ones can be frustratingly difficult.

[Tex_NL]

@Sharpy's craft has a very high TWR. A big engine on a lightweight craft. With enough thrust ANYTHING will fly.

[Kombat engineer]

is it a rover... is it a jet.... NO ITS SUPER-ROVER!!!

[Sharpy]

6 hours ago, Tex_NL said:

@Sharpy's craft has a very high TWR. A big engine on a lightweight craft. With enough thrust ANYTHING will fly.

what about "This end towards space"? With enough thrust pointed downwards...?

[James Kerman]

But does it even lift, bro?

[joebopie]

1 hour ago, James Kerman said:

But does it even lift, bro?

well. errrrmmm. yes

[Sharpy]

12 hours ago, StahnAileron said:

I'm actually interested in seeing what the aero-forces on that looked like.

Damn. In this thing EVERYTHING produces lift! Even the stupid small tank. Even the intakes! The only parts that produce drag seem to be the Akita seat (which should be occluded by the cargo bay!), the engine, and the wheels (minuscule amount).

[Carl]

At a guess maybe the intakes have lifting body properties?

[Sharpy]

28 minutes ago, Carl said:

At a guess maybe the intakes have lifting body properties?

Not through ModuleLiftingSurface but their flat sides do produce lift bypassing the module, just following the drag model. So do the panels. So does the *trailing* side of the car. So do the large panels on the bottom. Pretty much only the engine, seat and wheels don't.

[LordKael]

17 hours ago, StahnAileron said:

At least we know body-lift can actually be practical. (I usually have to be going at absurd speeds or horrendous AoA to see the light-blue body lift forces when I'm testing craft.

Keep in mind that this is actually exactly what happened... His AoA was 45 degrees, and the TWR was phenomenal. A 100+m/s take off speed for a craft that probably weighs 5-9 tons, max, is absurdly fast. 

[tseitsei89]

5 hours ago, Sharpy said:

Damn. In this thing EVERYTHING produces lift! Even the stupid small tank. Even the intakes! The only parts that produce drag seem to be the Akita seat (which should be occluded by the cargo bay!), the engine, and the wheels (minuscule amount).

Everything produces lift if you go fast enough........ That is why a car might want to fly at high speeds.

 

[samstarman5]

19 hours ago, Sharpy said:

In one hand - yes, that's probably the reason. On the other hand - nothing is marked 'lifting surface', .....

You are right, nothing is marked lifting surface. And yet I've had nosecones refuse to touch ground for the longest time after accidents.

Even with all the work done to improve aerodynamics in the game, one is still likely to find the unlikeliest of parts floating in the wind like they were a kite.  And that's okay.