On Jul 16, 9:00 pm, wrote:
Hi,

I have noticed by watching the videos athttp://www.fulldeflection.com
, that the radial engines of the Sukhoi etc, allow more vertical
penetration, but all the Red Bull Air Race planes have boxer engines.

I would have thought that the radials would have more engine torque,
thus pulling the planes around the course quicker.

I look forward to some expert input on this.

Superdoof.

Horsepower is a function of torque and RPM. Radials often
generate their HP at lower RPM so would need higher torque at the
lower RPM to get the same overall HP out of them. The radials you see
doing aerobatics are often the Russian ones, and they're geared so
that the engine runs at a higher RPM to produce more HP from a smaller
engine, while the prop turns fairly slowly and loses less energy to
drag and also allows a larger prop diameter and therefore better
vertical performance. The radial's drawback is its higher frontal drag
that limits forward speed, as someone already mentioned.

Dan