How do i unlock these ?

Hey... { @SpitOnMyMinchia }

Login to Battlefield 1 Companion, go to LOADOUT and find the Light Tank..

[Am not working for EA, If is answer good pls give me XP or accept as solution.]

Thanks for using ANSWERS HQ!

 Another option works like this: join the game and wait in deployment screen until tank/plane becomes available. Once it does, click on it and click "Customize" in deployment screen. You will be sent to customization screen, where you will be able to use war bonds to buy new vehicle loadouts.

Also, just so you know, the loadouts you mentioned are Howitzer for light tank, Flamethrower for heavy tank and Bomber Killer for fighter. Just keep in mind that Howitzer's turret has a limited turn angle and Bomber Killer's rockets are not really effective against ground targets (although they are capable of killing infantry if aimed well) - they deal massive damage to planes and usually can damage wing with 1-2 hits though. Flamethrower tank replaces two side guns for gunners with flamethrowers with 25m range.

@SpitOnMyMinchia

If you'r in a game in the Spawnscreen, if there appear a Vehicle symbole(Tank/Plane) byside you'r Base symbole, then if you switch the cursor on it you should see the option for "Costumize Loadout". There you can switch between all the Tanks and Planes then, and Buy/Equip other Loadouts for it.

Greets,
Travis

( Please Leave XP and accept it as Solution if it helped you) Thanks