"Ohh", says Jack, "I think I have a prototype version of that helmet. Stay here, I'll be right back". He scoots to another room and after a while he comes back, stripped nude, but with a blue helmet. As you see his junk you avert your view, yet still are curious as to how the transformation would look like on someone else.
"Here it is", he continued, "It's an earlier version where the change is still quite rough, but it works". He steps to a spot where he's as far away from any furniture as possible and takes a deep breath before putting on the helmet and flipping down the visor. Almost instantly he spasms contorting his body into impossible shapes. Piece by piece wings engines and control surfaces pushed themselves out as his legs shrunk down the same way as yours. His body extends downwards and to the back becoming the tail of the fighter. His design was sky blue with white stripes, just like the helmet. As the last step his face bulged out, forming the front tip of the jet. He wiggled his tail a bit and faces you, radioing, "Yeah there are some bugs in this one, can't talk normal now". What you see his now your uncle Jack, but as a rather stubby anthro jet fighter.
"Follow me", he radios to you, completely with a course you can apply to your avionics as he waddles out of the room. You follow him waddling to a door. He opens the door and it leads outside to a rather tranquil place. No other humans are to be seen or buildings, just meadows with some hills and mountains in the distance, as you look back you see the door belonging to the only building visible, a small shed. You find this rather odd, didn't you enter the building at ground level, and this clearly isn't where the shop was before. "It's nice to have a place of your own", he radioed to you. Then you realize that there is in deed a long tarmac strip acting as a runway.