I took the Better Half's Boxster S on a long, top down errand by the shore. Cloudy but warm and very gusty so I kept the top down through some light showers but got caught in some highway stop and go traffic when a downpour hit so I raised the top in motion (crawl speed, handbrake up just enough to light the light and allow top movement), but the top cover didn't fully retract, remaining open about 1 inch. No big deal, I figured i'd drive like this until the next exit. I do not typically do things like this, but we are talking maybe 3 miles.
Traffic cleared and I accelerated watching the cover to make sure it wasn't buffeting, which it never did. Then as I accelerated through ~70, the car started to feel very light and twitchy, completely unlike how it typically drives. The feeling increased with speed. Wasn't ight at the nose or tail, the entire car felt light. Then a crosswind gust hit that really caught my attention, enough that I slowed way down and pulled off at the next exit. The felt instability was very noticeable and, for the GA pilots here, felt very similar to the few seconds before rotation where the wing is starting to produce significant lift and the plane is light on its wheels and feels like it is skipping (it is not) down the runway. Fun in a Cessna...not so much on Rt 95.
I walked around the car with the cover still slightly raised and then it dawned on me. The Boxster has a small spoiler that raises at ~70mph and I assume that the slightly raised cover was smoothing the airflow from the top over the rear and also shrouding the rear spoiler, essentially causing the car to generate a considerable amount of lift...very effectively.
I built a wing.
I have even more respect for the engineers and aerodynamicists in Stuttgart to design a car and system like this. Less respect for me for disrupting it
Rather impressive demonstration though and another lesson learned.
Traffic cleared and I accelerated watching the cover to make sure it wasn't buffeting, which it never did. Then as I accelerated through ~70, the car started to feel very light and twitchy, completely unlike how it typically drives. The feeling increased with speed. Wasn't ight at the nose or tail, the entire car felt light. Then a crosswind gust hit that really caught my attention, enough that I slowed way down and pulled off at the next exit. The felt instability was very noticeable and, for the GA pilots here, felt very similar to the few seconds before rotation where the wing is starting to produce significant lift and the plane is light on its wheels and feels like it is skipping (it is not) down the runway. Fun in a Cessna...not so much on Rt 95.
I walked around the car with the cover still slightly raised and then it dawned on me. The Boxster has a small spoiler that raises at ~70mph and I assume that the slightly raised cover was smoothing the airflow from the top over the rear and also shrouding the rear spoiler, essentially causing the car to generate a considerable amount of lift...very effectively.
I built a wing.
I have even more respect for the engineers and aerodynamicists in Stuttgart to design a car and system like this. Less respect for me for disrupting it