Helicopters can't take off from landing pads or most places - how to change?

How is the interaction between helicopter rotors and the environment handled? Is it hard coded, or is it determined by a JSON factor that I’m not seeing? The reason I’m asking is because, as of right now, trying to take off or land your 'copter with even a simple rose bush nearby will cause your 'copter to shed rotors like autumn leaves, guaranteeing it will never fly again. This also means that 'copters beyond the 2-seater civilian model may not be able to land at heliports, which are designed for helicopters to take off and land from. This is annoying, at best, and while I know this has to be part of the same issues that cause vehicles with the mass of an 18-wheeler with full trailer to stop cold when running into a stunty sapling, it’s much less easy to work around.
Looking at the JSON:

  • I noticed that rotor diameter is defined, so lowering that might cut down the effect, but AFAIK the math that CDDA runs to let something fly is hardcoded. I don’t know if the rotor diameter is a minimum for a given type of helicopter to be able to fly, or if it only goes into determining if you shred your rotors like soft cheese if a pesky shrub sneaks up on you.
  • Cranking up the durability of the rotors leads to comedy (Apache helicopters make the best mass gardenscapers in all CDDA if you do that), but doesn’t stop them from flying to the four winds.
  • There doesn’t seem to be a vehicle flag that would solve this, at least that I can find. Haven’t pored through the general flags to a degree that would be helpful.

So is it possible to mod this to be less restrictive? If so, how? Or was this fixed on a later experimental build than I’m currently using (#10603, out of personal taste and because nested containers doesn’t look like much fun right now)?
(I have tried to track down helicopter related PRs for more info as to how this works, but I’m not good with finding things on GitHub)

There was a bug where rotors had twice the radius they should have for a bit, and I’m pretty sure it’s fixed on a build after yours.

Helicopters should drift a few tiles/turn randomly, which would encourage people to not land near obstructions without arbitrarily doubling the size of their rotors.

Use at least build 10640 to have rotor area fixed.

Thank you all for the information. Either I’ll update or just live with it, no fix with JSON here as it’s all C++ and therefore beyond my capabilities.