Hellicopter Crashes

[Daemion]

Something about how the standard rules treat rotor destruction on VToLs just didn't sit right with me. Still doesn't. For one thing, you have an aircraft that is subject to momentum. When the rotor is gone, they don't just drop out of the sky. Every helli crash that I've seen a video of, real or otherwise, generally shows a VToL generally careening in a wild manner before impact, and while 100 feet may seem pretty big, most modern VToLs take up a large fraction of that space.

The same can even be said for other VToL like units, like AirMechs.

So, I ended up brainstorming the following to give a little more realism to VToL crashes.

It's a simple matter of scatter.

For each level that the VToL drops, roll a d6 and compare with the BattleMech facing after a fall diagram (or artillery scatter diagram). If the VToL was using a Cruise or Flank Movement mode that turn, it only moves into one of the three hexes in it's front arc. Treat a rearward (4) result as forward, and the appropriate side directions go into the 2 or 6 hex respectively.

For resolution purposes, if the VToL was in a Stationary or Cruise movement mode, turn the VToL to face the hex it enters, since the next potential result can still swing it back the way it came. For Flank mode, it retains its facing at the end of the movement mode when moved into a new hex.

This keeps happening until the VToL crashes into something.

When it finally hits the ground, roll on the BattleMech facing after fall table to see which side takes the brunt of the impact, and resolve damage as normally described for falling units. (While we may have resolved with turns in the air, remember that it was still careening, most likely due to the stabilizer spinning the craft around as it went down.)

I'll come back with examples a little later.

[worktroll]

The sort of crashes you're describing come from loss of tail rotor control - the VTOL loses directional stability, and staggers drunkenly. Such in theory can't happen to VTOLs that don't use rotor blades (eg. the Yasha).

In the case of losing the rotor blades completely - eg. failure of the Jesus nut, or due to removal by enemy fire - the vehicle proper will follow a ballistic arc downwards.

It's possible that (at a scale well below TW rules) a VTOL loses only part of a rotor - but the high revolutions and imbalanced rotation will pretty soon lead to catastrophic loss of all rotors.

Question for real-world tech-heads- where a VTOL uses coaxial rotors to avoid need for tail rotors & the like, is it likely/possible to achieve a situation where one rotor fails, but the other keeps turning?

[Empyrus]

Pretty sure the failure of one rotor doesn't affect the other rotor. Depending on how it fails, of course. Like, blades shot off, no effect on the other...

If there is one engine, it drives both rotors. If there are two engines (and there typically are, for redundancy), each engine alone can drive both rotors.
No comment on axle jams or the like, it seems multi-rotor systems are pretty complex...

That said, i'm not quite sure what happens if one rotor fails in a two-rotor craft. In a co-ax arrangement, logically the helo would start spinning since it relies on the other rotor to provide counter-torque. A tandem arrangement is usually used for heavier helos, and i doubt one rotor alone is enough to keep it flying.

Do note, this is just from some light reading and logic (my logic, doesn't mean it is real). I take no responsibility if your helo fails somehow.

[worktroll]

And BT VTOLs may be immune from the effects of momentum ;)

Pretty sure twin-rotor jobbies like the Chinook can't deal with loss of one rotor issues ...

[Empyrus]

Even if a Chinook could stay up with one rotor, i'd imagine the torque issue would make it spin, though probably slower than other helos due to its mass and bulk.


Technically the game simulates attacks and damage happening on the move over 10 seconds, rather than at the target hex. Hence the TMMs and AMMs. So the end result is that a crashing VTOL probably does have momentum but it is not intuitively apparent, eg the rotor is lost midway through its movement and the momentum carries it to the final hex where it crashes.

[RunandFindOut]

Little complicated.  Far as it goes helicopter crashes tend to be quick but also involve a distinct lack of directional control.  I've played at a table where the following house rule was in play for VTOL crashes.  Roll two d6 of different colors, one represents which way the crashing VTOL traveled the other represents which way the VTOL is facing when it impacts, both relative to it's original facing.  It impacts the  ground a number of hexes equal to half it's speed at the time of the crash from where the crash was initiated.

[Daemion]

Even if a Chinook could stay up with one rotor, i'd imagine the torque issue would make it spin, though probably slower than other helos due to its mass and bulk.


Technically the game simulates attacks and damage happening on the move over 10 seconds, rather than at the target hex. Hence the TMMs and AMMs. So the end result is that a crashing VTOL probably does have momentum but it is not intuitively apparent, eg the rotor is lost midway through its movement and the momentum carries it to the final hex where it crashes.

Thanks for pointing that out. It's easy to forget that. Although, in my case, I don't see weapons fire happening during the entire 10 seconds because of recharge and reload times. But, a couple seconds worth in the turn, probably near the end of the movement phase might be just enough for such an assumption. I still think the direction it lands should be random.

The sort of crashes you're describing come from loss of tail rotor control - the VTOL loses directional stability, and staggers drunkenly. Such in theory can't happen to VTOLs that don't use rotor blades (eg. the Yasha).

In the case of losing the rotor blades completely - eg. failure of the Jesus nut, or due to removal by enemy fire - the vehicle proper will follow a ballistic arc downwards.

It's possible that (at a scale well below TW rules) a VTOL loses only part of a rotor - but the high revolutions and imbalanced rotation will pretty soon lead to catastrophic loss of all rotors.

Question for real-world tech-heads- where a VTOL uses coaxial rotors to avoid need for tail rotors & the like, is it likely/possible to achieve a situation where one rotor fails, but the other keeps turning?

You've never played with any self-launched helicopter toys, have you? Does anyone else remember the GI Joe hand launched one man copters? I had a couple, and they would spin, although not at the same speed as the blade itself. Now, if they had worked a twin-blade counter rotational rig into the toy, it would have been much more stable.

When I was envisioning a VToLs rotor destruction, I was thinking that there would be partials left before it hit the ground. You only need to clip one to send it to the ground. Secondly, when the rotor isn't providing resistance for the stabilizer, the stabilizer is going to spin the craft in the other direction. And, the rotor only does that when it's treading air, and not riffling it with fast spinning stumps.

And, as far as the Yasha is concerned, you can't glide her to the ground on a single engine like you can a wwII bomber. That displaced lack of counter-thrust is going to spin the craft, but in vertical spin, cartwheeling the craft.

Other than that, yeah, Balistic arc is right. That's why I decided to narrow the direction of travel if it used a movement mode. But, I can still see spin and air currents causing drift in random directions before it hits the ground.

Little complicated.  Far as it goes helicopter crashes tend to be quick but also involve a distinct lack of directional control.  I've played at a table where the following house rule was in play for VTOL crashes.  Roll two d6 of different colors, one represents which way the crashing VTOL traveled the other represents which way the VTOL is facing when it impacts, both relative to it's original facing.  It impacts the  ground a number of hexes equal to half it's speed at the time of the crash from where the crash was initiated.

It really isn't that complicated. You're rolling a d6, checking to see where it goes, check to see if it impacts the ground where it moves to, and then repeating the process.

Examples still pending.

[Daemion]

Example one: Stationary Copter

A Warrior Copter is practicing the art of not being seen, parking itself at level 5 above a 3 level hill in front of a light woods hex on an adjacent 3-level tall hex. There's one more hex that's three levels tall, (hex 5 if you placed the facing after a fall diagram on the Warrior's hex aligned with its nose) and all the rest fall away one level at a time.

It was stationary this turn (bad initiative roll), and was caught by surprise when a Harasser Hovercraft came flying in past the lake. The SRM barrage was enough to take the rotor out, and now it's time to kiss the dirt. According to the rules, the controller rolls a d6 and consults the BattleMech Facing After a Fall table to find out which way the Warrior drifts in its fall. Since it was stationary that turn, it could potentially go anywhere.

If he rolls a 4, it will immediately drift into the woods causing an auto crash in that hex. Any other result gives it at least one extra roll before it hits the ground. In this case, the controller rolls a 6, sending the Warrior into the forward left hex, which happens to be a level two hex, and the VToL drops one elevation level. It is now at level 4. It's facing has now changed to one to the left from its original orientation. It hasn't crashed yet, but it will.

This happens again, another roll of six. From it's original position it is oriented two hexes to the left, just out beyond the clear level 3, and it is now at level 3, above a clear level 2. It looks like it's circling that one level three hex.

The next roll is the last roll, as the controller rolls a 5, sending the Warrior backward and left onto the level 3. As it would drop to a level 2 it is below the hill line and crashes in the hex. The controller rolls 1d6 and gets a 3, which means the VToL takes damage from the fall on its right side. It only fell 2 levels before crashing, so the Controlling player modifies the falling damage accordingly, then applying it all to the left side armor and internal location.

[Daemion]

Y'know what, Worktroll. I think you're right. It does look like this should be from a combination stabilizer hit and rotor destruction. The reason I came up with the above is I wanted a little hex-by-hex wobble in the fall.

What I originally had in mind was using the Target or Attacker movement mod as a basis for distance traveled in a fall. So, A Cavalry attack hellicopter can move 10/15, and is armed with short range armament, requiring it race into close range of a target. It can generate a 5 TMM while either under cruise or flank.

So, instead of having multiple rolls, just one roll for direction? In the case of generating anything other than a 1 for being airborne, roll a d6, consult the facing after a fall chart? Or would people prefer the modified artillery/bomb scatter chart where 1-2 is left, 3-4 is forward, and 5-6 is right? What I had in mind for the facing after a fall chart is that 3 would count as 2, forcing the VToL to the forward right, while 5 would count as 6, forcing it to the forward left, while 4 would count as 1, effectively folding the chart onto itself.

Then, the TMM is the number of hexes traveled. And another d6 to find out which body location takes the brunt of the damage via the facing after a fall chart.

I personally still want a little wobble in the fall, and want to see a bit of decline in elevation, to allow for early crashes, should it encounter something along the way, like a combat unit. ;)

So, maybe it moves AMM number of hexes before dropping an elevation, and still have a slight potential for drift, left or right.  And like a stalled aircraft, it resolves the crash in the next movement phase, instead of at the end of the weapons fire phase. I suppose if it's just rotor destruction, it's pretty predictable and is resolved first before everything else moves, giving units a chance to get out of the way with a PSR, and finish their move. If it's a whirly stabilizer damage fall, then it should move completely last, being completely erratic and unpredictable.

Yes, I'm just pitching out ideas here. What I have currently is easy to do, but it's still not as logical as I'd hoped. But, I hate the static scatter charts and want a little more wobble in a VToL's fall.

So, if you have something that you can throw at me to convince me on a direction, (pun not intended, but feel free to cringe, anyway) by all means.

[worktroll]

Part of the issue is that any game's necessarily an abstraction. The level of detail one person finds sufficient won't satisfy another, and vice versa.

So while I'd just say "it crashes", there's nothing wrong with you wanting a more cinematic ending ;) Just I don't feel the need for the level of additional detail, for me.

W.

[RunandFindOut]

yeah I'm somewhere between the two of you.  Just saying "it crashes" and having it drop straight down on the spot doesn't quite work for me.  But his rule is much to complicated and takes too long to resolve for what should be a fast mechanic.  I rather liked the simple roll to determine which direction it crashed in and which direction it was facing when it hit the ground and moving it half whatever movement speed it had in that direction.  Quick, easy to resolve, but gives a more satisfying result than, it drops to the ground right on that spot.  Even if it may have been hundreds of meters up and traveling faster than a sprinting locust at the time.

[Daemion]

I actually agree with you, Run, about the complexity. Although half the speed it used is a little much. I'm thinking the target movement modifier the copter generated, and it'll be based off the facing of the copter at the time of rotor destruction. That value is based of the number of hexes the VToL traveled, after all, and is easily references with little extra math.

I'm thinking I want to resolve it like an aircraft going out of control in the air portion of the game: It resolves the crash during the next movement phase, and can potentially run into somebody. Ballistic arc means it should probably resolve first, giving any potential collision targets the chance to get out of the way if they're capable.

Ooh. Fun thought, it travels up to its TMM of the prior turn, and skids on the ground a number of hexes equal to it's AMM of the prior turn.