Our drum corps has Yamaha 18-22-24-28-32.
We would like to go away from the 32 only because of not having someone to carry it (well) at this point.

I was thinking shifting up one drum and adding a smaller #1.
we may end up back with the 32 but until #5 can build some strength we may go the smaller drum setup.

(14 or 16)-18-22-24-28

I personally like 18-20-24-28-32 in a drum corps setting. In smaller open class or senior corps I could see have smaller drums because you don't need as much sound to balance the hornline.

A 16 will almost always get lost in the hornline and a 14 is useless for sound production outside.

The current sizes you have are unusual intervals; most teams will use a tighter grouping up top and space them out between 3/4 and 4/5.

For HS, I like 16, 18, 20, 24, 28.

For corps, my preference is 18, 20, 22, 26, 30.

Outdoors, I personally wouldn't use anything smaller than an 18" drum. In your situation, I'd slip in a 20" drum as your #2 and go 18-20-22-24-28.

I'm using this exact setup with a high school right now. You won't get the same thunder you'd get from a 32" bottom, but these sizes work pretty well for situations where you can't march a 30+ bottom.

I'm liking that 20" idea. 18-20-22-24-28 for now.

Then eventually go to: 18-20-24-28-32?

I love 18-20-22-26-30, if you tune them right.

yes, use that for now. the 28 bottom will suck, but oh well. OR ditch the 22 and 28 and get a 26 and 30.
the BEST sizes would be 18, 20(or22), 24, 28, 32

have there been any groups marching a straight interval of 4 inches? 16 - 20 - 24 - 28 - 32?

Citations? I was in Citations 1967-71 !!!

i'm sure there have been some. but, 16"ers are just too small. i don't think they get the job done outdoors at ALL