The Great Piston Engine Thread

[klond]

13 hours ago, Azimech said:

and certainly never capable of powered flight.

Challenge accepted!

aaaaand challenge failed :-(  Damn near 10 m/s.  It will spin alot of propellers, but they just add weight :-/

If gearing wasn't so inefficient (for the reasons Az mentioned above) we could convert this nice torque to speed.

Edited September 10, 2016 by klond

[Majorjim!]

4 hours ago, klond said:

aaaaand challenge failed :-( 

As Edison would have said, you only have to find one way to make it work!

 Keep at it man.

[klond]

 K, dudes are posting cannons on kerbalx from 1.2.0.  Can someone explain what's propelling their cannonballs?  I'm interested if this could be is a new power source for engines? *rubs hands together

[Azimech]

38 minutes ago, klond said:

 K, dudes are posting cannons on kerbalx from 1.2.0.  Can someone explain what's propelling their cannonballs?  I'm interested if this could be is a new power source for engines? *rubs hands together

Isn't it just a rocket/jet engine? Can't imagine anything else.

But I'll check.

[Majorjim!]

6 hours ago, klond said:

 K, dudes are posting cannons on kerbalx from 1.2.0.  Can someone explain what's propelling their cannonballs?  I'm interested if this could be is a new power source for engines? *rubs hands together

Something to do with landing legs me thinks. From that stream recently. It will likely be patched out though.

[fourfa]

I think I watched all the relevant DasValdez streams.  One cannon design uses vector engine (or 2 or 5) with a small fuel tank, and a projectile attached to its lower attachment node.  If you use docking ports and offset the engine-side port just behind the thrust transform origin, the port will remain there and can be reloaded.  You can use the hollow airplane fuselage as a barrel but it's strictly cosmetic.  I saw this shell the island runway from KSC, or shoot 40km completely over the island.

There is also a landing leg trick you can use involving legs that are clipped into a projectile while deployed, then undocking the projectile.  Can also yield extreme dV/ range.

Edited September 17, 2016 by fourfa

[Colonel Cbplayer]

7 hours ago, fourfa said:

I think I watched all the relevant DasValdez streams.  One cannon design uses vector engine (or 2 or 5) with a small fuel tank, and a projectile attached to its lower attachment node.  If you use docking ports and offset the engine-side port just behind the thrust transform origin, the port will remain there and can be reloaded.  You can use the hollow airplane fuselage as a barrel but it's strictly cosmetic.  I saw this shell the island runway from KSC, or shoot 40km completely over the island.

There is also a landing leg trick you can use involving legs that are clipped into a projectile while deployed, then undocking the projectile.  Can also yield extreme dV/ range.

The question is... How do we build a Orion style rocket propel this way?

Edited September 17, 2016 by Colonel Cbplayer

[Rath]

Wow, it's been this long!

 

[fourfa]

Addendum: I didn't watch in the wee hours of the morning, by which time the physics of compressed landing legs (which apparently impart impulse with no physical constraints?) had produced an orbital bombardment cannon with 156km/s of delta-V.  Try from about the 12 hour mark on

https://www.twitch.tv/dasvaldez/v/89258144

Edited September 18, 2016 by fourfa

[klond]

Not 'real world,' but slapping some small pistons around inside a tube is close enough for me.

stock functional V8.  Nice small tight package.  Each piston reaches top dead center at a different time, just like real life.

I tried a design without the center crankshaft bushing, but the long, unsupported crankshaft flexed too much under full power.  Unit would be a little more compact without it.\

It is self-starting tho, so I'm pretty happy.  You guys like the dual quad "carburetors"?  Ain't that crank just smooth as butter?

Edit: modified the intake plenums.

KerbalX

 

Edited October 30, 2016 by klond

[Azimech]

Looks cool klond! If you install VOID you'll know the max rpm it produces.

[Majorjim!]

7 hours ago, klond said:

stock functional V8

Damn dude.. A KSP first. That's rare, awesome work on this man.

 

[klond]

 Thanks guys!  I'm really happy with the look of the whole piece.

 We should try to put this into something.

 Is VOID ready for 1.2?

[klond]

1.2 has been good to me.  Some parts, like thermometers, can be stretched and floated far away (infinite?) from their parent part.  It has allowed me to do new stuff like this.

 

Lil baby go kart engine!  Had to make my own cylinder.  It's nice we can kinda see thru it.  I had to pick a rounded object for the piston (I think it's a RCS Anywhere port) - a flat object had more thrust but the edges would catch on the cylinder walls.  'Had to use SAS for 'electric start'  :-).   Unit probably doesn't have any extra usable power.  I'm surprised each pulse gives enough momentum to go 360 degrees.  Historically I've had to use multiple cylinders to provide oomph to get the others in position.

I like watching the counterweights go round.  Majorjim technology engaged!

 

Edited November 8, 2016 by klond

[life_on_venus]

On 30/10/2016 at 8:51 PM, klond said:

 Thanks guys!  I'm really happy with the look of the whole piece.

 We should try to put this into something.

 Is VOID ready for 1.2?

I'll download your V8 sometime and watch as it melts my drivetrains to pieces 

Seriously though I think that you could mount it transversely. Use a 3:1 gearing or something to connect it to a driveshaft that runs below it, with a wheel on each end. Cheap, powerful drivetrain for an RR layout car. V8 kerbal Porsche anyone?

Ooh, on a different note, has anyone got a regular transmission to work yet? I tried building a 2 speed the other day but failed

Edited November 8, 2016 by life_on_venus
Transmission

[V7 Aerospace]

So if I'm right, the largest piston engine we have is a V8, surely a V12 is just around the corner then.

After that, what next? Is anyone trying any other layouts apart from V's and flat engines? Or are these layouts the only ones possible as of now.

It'd be great to see some massive engines in the future, like the H-24 Napier Sabre (one of my favourites from WWII)

Edited November 8, 2016 by V7 Aerospace
Finally got the image

[Majorjim!]

57 minutes ago, klond said:

1.2 has been good to me.  Some parts, like thermometers, can be stretched and floated far away (infinite?) from their parent part.  It has allowed me to do new stuff like this.

Lil baby go kart engine!  Had to make my own cylinder.  It's nice we can kinda see thru it.  I had to pick a rounded object for the piston (I think it's a RCS Anywhere port) - a flat object had more thrust but the edges would catch on the cylinder walls.  'Had to use SAS for 'electric start'  :-).   Unit probably doesn't have any extra usable power.  I'm surprised each pulse gives enough momentum to go 360 degrees.  Historically I've had to use multiple cylinders to provide oomph to get the others in position.

I like watching the counterweights go round.  Majorjim technology engaged!

 

Nice work dude! I am always happy to see my thermo hinges put to good use! Looks like you could have placed the thermos on those Ibeams and not really needed much in the way of offset. Same for the cubic struts.

[life_on_venus]

1 hour ago, V7 Aerospace said:

So if I'm right, the largest piston engine we have is a V8, surely a V12 is just around the corner then.

After that, what next? Is anyone trying any other layouts apart from V's and flat engines? Or are these layouts the only ones possible as of now.

It'd be great to see some massive engines in the future, like the H-24 Napier Sabre (one of my favourites from WWII)

Yep, we have V engines and Inlines so we could do W engines (of both types) and H engines I suppose. The difficulty with H engines is keeping both crankshafts from slipping at speed. That, and the torque might overpower any clutches we built

[Azimech]

I'm still waiting for Infernal Robotics to be updated, then I'll continue development of Kerbal Piston Engines.

[klond]

1 hour ago, Majorjim! said:

Looks like you could have placed the thermos on those Ibeams and not really needed much in the way of offset

 You're right, but I had to think about this for a minute.  I guess the only reason I didn't is to gain leverage with more offset.  See technical document below.

[Majorjim!]

20 minutes ago, klond said:

 You're right, but I had to think about this for a minute.  I guess the only reason I didn't is to gain leverage with more offset.  See technical document below.

Why do you need leverage for the thermometers?

[klond]

You just want more art  :-)

NO

Fragile little antennas (antenni?) need all the help they can get.

 

 

[Majorjim!]

Just now, klond said:

You just want more art  :-)

Huh?

Just now, klond said:

Fragile little antennas (antenni?) need all the help they can get.

 

But offsetting them further form the connected part decreases the strength of the connection.

[klond]

 Less twisting and pressure.  Like having a longer lever.

[Majorjim!]

Just now, klond said:

 Less twisting and pressure.  Like having a longer lever.

Yeah I understand the concept of a lever dude. Did you try it with them not offset as far because the further you move them from the attached part the less stable they become that's just a fact of the game mechanics. Looking at the design it seems that was your only choice, to offset them quite far, lucky you can do that in a stock editor. Have you tried the no offset limits mod? It's a real part saver on more complex designs.