Are you sure about that, because i seem to recall in Homestead episode it does extend its nacelle
I saw this one not long ago. I didn't see it extend its warp nacelles, but it did show off it's pop-out impulse thrusters if I remember right. The second Flyer had fixed nacelles (seen well here), but did have two extendable impulse engines on each side.
Both versions of the Delta Flyer featured retractable warp nacelles, but while the first version only featured a standard impulse drive, the second version employed retractable impulse thrusters that greatly increased the vessel's impulse speed when deployed.