Behavior Of Police Helicopters In Car Chases Options

[Squire]

[Herald of Verjig...]

A while back I saw an article about the specs of the "New and Improved" Commanche helicopter design. I remember it having a large array of stealth options including ways to avoid IR detection, radar, and I think a way to minimize the engine noise. I have been unable to find the information online, but maybe someone can find the relevant numbers.

[Daishi]

Before the local airshow a couple weeks back, I would watch from my backyard as planes and choppers fly over head on approach. Older birds that were obviously two bladed were noisey as all hell. The newer 5 bladed choppers that I could identify, I only noticed because I was in the backyard and it was otherwise quiet.

For canon rules, I believe the perception target number is the chopper's sig, modified by distance, other noises and distractions. I'm infering this from the comment in rigger3 about smart materials adding +1 to the sig of a chopper for listening perception tests.

[grendel]

Out in an open field, still air, you can hear a chopper coming from a ways away, probably close to four or five miles. Maybe more if you have exceptional hearing. In an urban or forested environment, though, the ambient noise combined with the reverberation and redirection of the helicopter's noise can allow it to sneak up on you quickly. Also, you may not be able to determine the direction of approach until its very close, within a mile.

Given a proper masking structure, a helicopter moving at 120 kts can be on top of you almost before you know it.

Five bladed systems are inherently more quiet than four or two bladed systems, and certain rotorhead bearing designs can reduce noise as well. Most rotors feature blade tips that are swept between fifty and seventy degrees. This is for noise attenuation as well.

As for the Comanche, the helicopter has five blades with swept tip caps and a fan in fan style tail rotor. Both of which are designed to reduce noise signature. Exhaust from its engines is funneled through passive IR suppressors, basically a large number of vents along the extended tail boom. This reduces their heat signature to within about thirty to forty percent of ambient air temperature. The Comanche's skin is composite RAM and sculpted with an eye for stealth.

[Ed_209a]

I think Seattle's Lonestar security forces would rely almost entirely on drones. Drones for surveilance, drone s for pursuit, drone gunships if needed.

[Kurukami]