radial engine torque

Hi,

I have noticed by watching the videos at http://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.

On Jul 16, 11:00*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.

I'm no expert but I know that during WW2 the USAAF decided to use only
radial engines on primary training aircraft, even those built with
inline engines were redeveloped with radials. The reason was because
the radial allowed for quicker climbs to altitude because the engines
remained cooler in the climb with all cylinders exposed fairly equally
to cooling air; level flight speed was not important on short training
hops. I would think the radial engined aerobatic aircraft would have
a similar advantage in climb rate but not so much in level flight due
to drag. Over the length of the Red Bull course the inline opposed
engines would have a speed advantage compared to the radials.

John Dupre'

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