Hi Don
Yes you are correct the GL is a grenade dicharger, with the proviso that the grenade has to have a propulsive charge attached to its bottom making it remarkably similar to a mortar bomb.
If you were to compare it to a 'bona fida' grenade launcher, say the M79, we find some important differences, The GL bomb has to be dropped down the barrel rather than loaded at the other end. As the bomb is a loose fit you cant fire it at less than horizontal, it will slide out again, and at anywhere near horizontal you are risking a missfire as the bomb may have moved back up the barrel. You also have to fire it with the base against something solid not your shoulder.
But it does make quite a good little mortar heres why.
From
http://members.shaw.ca/nambuworld/t89pix.htm
"the weapon is always held at a 45 degree angle to the ground, and some even had a
spirit level sight to let you know when you were at exactly 45 degrees"
The GL changes the -length- of the barrel (not the angle of the barrel as in a 'true' mortar) to alter the velocity of the projectile and so its range. This is important because as your not changing the angle of the barrel you dont -need- a bipod to adjust tube angle you just need it to support the GL barrel at 45 degrees. The Japanese decided that it was better to just train the operatot to hold it at 45 degree and save the weight of a support/bipod.
Id wager that the GL is calibrated/designed so that at 45 degrees the bomb travels to exactly the range you set on the range scale using the range adjustment knob. So firing blind you can lob the bomb to whatever distance you want, if you can just hold it at 45 degrees(note some have spirit levels). So you can use it to hit preregistered or 'known distance' targets. ie you can use it accurately against a target without having the target in view, the critical difference I would think between a grenade discharger and a mortar.
If you have a spotter you dont need to have it at 45 degrees anyway, you just have to hold it at the -same- angle throughout the "shoot" and it performs exactly the same as any other small mortar. The spotter, say crewman No. 3 is the only one who needs to be in LOS of the target. He calls the correction and the firer, crewman No. 1 adjusts the range on the scale using the "range adjustment knob". The loader, No. 2 is arming the bombs and dropping them down the barrel. Once zeroed, all No. 1 does is hold the GL steady and pull the trigger. ie
No. 1 is the bipod. Its a very Japanese idea. Note Wiki states it has a 3 man crew, like any other light mortar.
The range scale goes from 120 to 650 m. ie The GL has a minimum range owing to its plunging trajectory and inability to shoot at shallow angles, like all mortars.
So what can a brixia or any other light mortar do that the knee mortar cant?
Also from
http://members.shaw.ca/nambuworld/t89pix.htm,
"The Type 89 was extremely accurate in the hands of a skilled operator"
This is because unlike regular mortars it has a barrel instead of a tube, ie rifling (another source of confusion with grenade dischargers no doubt along with the trigger). Though the bomb will fall out if you point the barrel down, once fired a copper band expands giving a seal and engaging the rifling, rifling equalling better accuraccy when compared to a typical mortar.
As a matter of semantics, this site calls the GL's bomb a mortar round.
http://www.inert-ord.net/jap02h/knee/index.html
Note also that the bomb has a mortar type impact fuse rather than the grenade discharger timer fuse.
Though your Wiki quote does say that it isnt a true mortar it doesnt say why. Your quote says that its similar to a grenade launcher but only because of its "lightness and general handiness" not because of its method of employment. The link also says,
" ...knee mortar... braced against the ground when shooting, in this respect resembling the conventional mortar family"
Looking at some of the units currently in the game,
USA formation 223 "Infantry Co" has 3 60mm indirect fire mortars range 40 hexes
USSR formation 009 "Rifle Company+" has 3 50mm indirect fire mortars range 16 hexes
Italy formation 104 "Co Fanteria 40" has 3 45mm indirect fire mortars range 12 hexes
Germany formation 433/434 "Inf Kp (GrW)" has 3 50mm indirect fire mortars range 10 hexes
So why cant the Japs have theirs?
Though Mobhack said there will be no rifle platoons with silly little tiddly-mortars inside of the rifle platoons The German fomations above do contain silly little tiddly-mortars inside of the rifle platoons. Also Mobhack called them silly little tiddy -mortars-, not silly little tiddy grenade dischargers, Mobhacks service is I believe in mortars.
The reason I persist with this is because I consider that modeling GL as a Grenade discharger rather than an indirect fire light mortar is an error in your OOB. Changing it to such would be a great way to add a lot of interest to the Japanese OOB, exactly because the Japanese have so many of them.
Well sorry for any offence caused intentional or not. I will try not to abuse anyone further or adopt a sarcastic tone.
I hope that I have brought something to the table that you were unaware of.
Best Regards Chuck