After months of serious flying around with the B737NG, I thought I knew every surface feature by heart.Then I noticed something strange.When the wheels are raised, they go into the aircraft belly. But unlike other commercial jets (PSS Airbus 319 for example), the wheels remain visible. There is no round plate to cover them.I don't get it. If the aircraft skin is not continuous and flush smooth, isn't this going to create a lot of drag?What about the -60C temps at FL350. Doesn't that affect the tire rubber and the hydraulic system moving the wheels?Eytan Ornstein

Hello Eytan,You'd have ask the Boeing engineers that one. I'm sure there is a good reason for it.Cheers,Bryan

Hi EytanI have flown 737's from their early days and none have gear doors over the main gear wheels. There is a reinforced rubber blade petal seal between the tyre and fuselage effectively sealing the gap. Also the outer wheel on each main gear has a faired hub cap to ensure a smooth profile. You must also remember that without a door and closing mechanism weight is saved. The 737 main gear wheel well is very limited in space and I doubt there would be any space for such a mechanism. The system is simple and works very well. Boeing must have done wind tunnel tests to measure drag and one must assume they found that the extra drag, if indeed there is any, is sufficiently negligible to justify the system they use.RegardsChris

Thanks Chris for the info. Just goes to show how similar demands create different engineering solutions. That's human igenuity at work!Eytan

I remember reading about this, granted im no Boeing expert but...The gear mechanism adds a lot of weight, as does other "cool" things like the Optional AirStairs. Boeing decided to increase orders by reinforcing the seals and picking good tires. The lightened load, means more passengers, which means more $$$.