Overheating: RAPIERs, LV-Ns, and the TVR-400L

[LordFerret]

I've had a number of problems (failures) in the past using clusters of Rapiers with rocket fuel (LiquidFuel plus Oxidizer) or LV-N Atomic Rocket Motors on the TVR-400L Stack Quad-Adapter ... the motors overheat and explode. I'd found very little on the forums as far as solutions to this problem, aside from the mention of trying Thrust Limiting or adding EAS-4 Strut Connectors; The main point made was the need to dissapate heat. So, I did a few tests. All tests involved 100% throttle static burns, with screenshots taken after overheating stabilized and remained constant. Below are my (unscientific) results.....

Test #1:

LV-N cluster on a TVR-400L (left inset) vs LV-N cluster attached to FL-T100 Fuel Tanks attached to a TVR-400L (right inset)

Overheating reduced about 60%; use of four (4) FL-T100's adds 2.25 tons to mass and 0.8 drag.

Test #2:

RAPIER cluster on a TVR-400L (left inset) vs RAPIER cluster attached to FL-T100 Fuel Tanks attached to a TV-400L (right inset)

Overheating reduced about 5%; use of four (4) FL-T100's adds 2.25 tons to mass and 0.8 drag.

Test #3:

RAPIER cluster on a TVR-400L with one (1) Cubic Octagonal Strut attached to each engine (left inset)

Overheating reduced about 40%; use of four (4) Cubic Octagonal Struts adds 0.004 tons to mass and 0.8 drag.

Test #4:

RAPIER cluster on a TVR-400L with two (2) Cubic Octagonal Struts attached to each engine (left inset)

Overheating reduced 100% (no overheating); use of eight (8) Cubic Octagonal Struts adds 0.008 tons to mass and 1.6 drag.

Test #5:

RAPIER cluster on a TVR-400L with one (1) Small Hardpoint attached to each engine (left inset)

Overheating reduced about 40%; use of four (4) Small Hardpoints adds 0.08 tons to mass and 0.8 drag.

Test #6:

RAPIER cluster on a TVR-400L with one (1) EAS-4 Strut Connector attached to each engine and connecting to the engine on its right (left inset)

Overheating reduced about 40%; use of four (4) EAS-4's adds 0.2 tons to mass and 0.08 drag.

Test #7:

RAPIER cluster on a TVR-400L with two (2) EAS-4 Strut Connectors attached to each engine and connecting to the engine on its right (left inset)

Overheating reduced 100% (no overheating); use of eight (8) EAS-4's adds 0.4 tons to mass and 0.16 drag.

Of course, out in space drag will not be an issue. Based on that, my build preference will follow the path of Test #4. Feel free to comment of course.

[Stargate525]

WHY didn't you post this a week ago? I just had one of my NERVA's detonate on its departure burn to Jool... I'm now limping there on three-quarter thrust. Will definitely be keeping this in mind in the future!

[Starwhip]

Part heating makes no sense.

Hopefully the next update will address it.

[Guest]

IIRC (according to NathanKell) heat temperature transfers from one part center to another so long as the centers are < 4.5m apart, which is why many things directly attached to an orange tank overheat faster (the old "slap a 1/4 over a Mainsail" trick). Having four hot engines attached directly to the four-way connector means they're all transfering heat in while it transfers heat out (but not to the orange tank).

Edited February 13, 2015 by regex

[zekes]

Part heating makes no sense.

Hopefully the next update will address it.

yeah, especially since re-entry's being added... that's a helluva time to find out what heats when.

[Mahnarch]

Interesting.

Good work. Take the rest of the afternoon off.

I'm just going to run over to the paten....errr the ice cream store.

[LordFerret]

WHY didn't you post this a week ago? I just had one of my NERVA's detonate on its departure burn to Jool... I'm now limping there on three-quarter thrust. Will definitely be keeping this in mind in the future!

I had pretty much the same problem, an LV-N cluster (as pictured in Test #1) blew one of the motors on the way out to Jool. The remaining three left the ship unbalanced during the burn, and I had to shut one of them down (keeping it symmetrical). That's what prompted me to do the tests lol.

[Foxster]

The small hardpoints, struts and connectors are all massless. Use as many as convenient.

I usually add octostructs to the bottom of a tank and attach multiple engines to them. This saves the mass and bulk of adapters and overheating is practically eliminated.