In Hugin, I want my panoramic photos to be warped around a sphere, so the output is an equirectangular stitched image. However, when I align them, they appear in the preview as a connected strip, warping around the sphere, but leaving black space at the top and the bottom. I think I need an equirectangular projection with Hfov and Vfov of 360 and 180 degrees, respectively. Obviously I've tried to match these settings in the projection tab. I've tried to scale the images, crop the canvas and a lot of other stuff. The result is always wrong so at this point I have no idea what to do.
You don't have sufficient scene coverage for an equirectangular. 360x180 coverage means you took enough photos and stitched to cover the entire sphere. If you didn't point your camera straight up and straight down at any point to take a member image, you have no coverage of the zenith (top) and nadir (bottom) of the sphere, which is why those areas are black when you try to reproject.
Just to give you an idea, an 18-55 kit lens, @18mm, requires roughly 30-40 images (about 4-5 rows of 5-6 images each) with enough overlap for stitching to cover a sphere. It's much more shooting than most beginner pano shooters realize.
Reprojecting a pano does not create missing data. Stretching/warping a cylindrical pano with less than 180° vertical coverage just gets you weird zenith/nadir seams.
You could try resizing your pano to a 2x1 rectangle and pretending it's an equirectangular when you bring it into Hugin (set lens type to
equirectangular and HFOV to
360), but I doubt you'll like what you get.