Identification of Chinook Type

Two of the easiest visual giveways to differentiate between 46s and 47s are the number of landing gear struts (three on CH-46s, four on CH-47s) and the fuel pods/sponsons.

On 46s, the fuel cells are located in what resemble stub wings located on either side just forward of the ramp. On CH-47s the fuel cells are located in pods faired into both sides of the aircraft and run the length of the fuselage from the ramp to the crew door on the starboard side and just short of the forward cabin window/escape hatch on the port side.

As Darin mentioned the interior is somewhat smaller and the fuselage has more of a curve to it whereas on '47s the interior is bigger and has a square-ish appearance.

A model: tail pylon was not squared off blades were symetrical.
B/C model Tail pylon was squared off. droop snoop blades bigger engines fuel capacity was ibcreased by 2000lb.
Don't know the D.
Flew them a while back in SE Asea

Lot of folks (media types, in particular) confuse the CH-46 Sea Knight (Phrog) with the CH-47 Chinook.

I saw video on TV from NOLA that showed -46s working, and they kept saying "these Marine Chinooks.." (and my wife just glanced in my direction with that "mind your outburst, the kids are in the AO" look. She knows. Hell, she can tell the differences nearly as well as I can..)

Without going into all the minute differences, which, for the uninitiated pax might go unnoticed (ie. You can say "Engines on the inside, or outside?", and if the pax didn't look up while getting on the aircraft he might never have noticed), here are a couple of "gotchas" that are easily recognizeable for a passenger:

When you got on the ramp, did you have to duck? I'm 6' tall, and with an SPH-4 helmet and boots on and the ramp down I didn't really have to duck my head (although the first time you skid your helmet off the aft xmsn chip detector, you'll think twice about ducking a little just in case..) in the ramp area of a CH-47, nor in the cabin. In a CH-46, however, I seem to recall having to kind of hunch my neck to keep my head off the soundproofing.

When seated on either side of the cabin, was there enough room in the middle to walk without bumping people's knees, or would people have to move their legs to one side or another so the crew chief could go fore & aft in the cabin? A CH-47 will take a Chevy pickup/blazer (M-1008 or M-1009) inside with the seats up, so its still pretty wide with the seats down. You can pile kitbags & rucksacks in the middle with little loss of pax legroom. On a -46 it was a little tighter, and I seem to recall that if you had a full boat of pax, they'd be "knee-to-knee" in the center of the cabin such that you'd have a tough time walking up the middle. A -46 might take an M-151 jeep, but I was pretty sure it wouldn't take a 1008 or 1009.

These are a couple of the differences right off the bat. Of course, if it was a side-loading single-rotored aircraft, it definitely wasn't a CH-47 or CH-46, anyway..

CH-47D Chinook: