My prostate was removed a little over a year ago, due to early stage prostate cancer. Now, I can get a useable erection via a pump system and cock ring. I don't need to use chemical aids. In fact, as part of my post-op therapy, I used the pump around 15 minutes a day, every day, and it worked quite well at gaining and maintaining an erection.
If you don't want to use chemical aids (Is there a reason we can't say the brand names?), try a pump. About the only unpleasant side effect we've encountered is that it makes the girth of my penis large enough to cause my wife discomfort upon penetration, although lube does help quite a bit with that.
It only takes a few minutes to get pumped up, and the erection lasts for as long as you leave on the ring (although it's not recommended you leave it on for long -- 30 minutes, I think -- due to the lack of blood flow.
Since I now ejaculate urine, not semen
, I've tried using a condom after pumping up. When I did, the condom put enough pressure on to push blood back through the ring's constriction and cause my erection to flop. So, if you depend on condoms for birth control, they may not work with a pump.
Filbert