Engine basics > Engine set up tips

Reduction drive

(1/2) > >>

ash:
When I finaly get around to doing a Hawker Typhoon for F4B scale, it will almost certainly have a geared reduction drive system to turn a near scale sized prop in the scale direction at the correct speed for flight.

With some of these huge engines now emerging under the new rules, we're seeing 16" props at under 7000rpm. I suspect a small engine with a reduction drive might be able to acheive the same thing with a possible weight or cost advantage.


Assuming weight and cost are not a detriment, does anyone have any thoughts on the viability of the idea in stunt?

RC Storick:
I usually won't reply in this section but I will this time. Engines are designed to develop peak HP at a given RPM. While true you could run gear reduction system on a engine but it will more that likely cause some problems with the application that we use our engines in. The prop pitch acts as a gear box. De pitching the prop to get the model speed where needed while still attaining peak HP for the given RPM range, Clear as mud!

Maybe Randy will post and clear the watter.

Louis Rankin:
Rather than use reduction gearing I would go 4 stroke or diesel.  Diesels will swing amazingly large props at lower RPMs.  Diesels also have a realistic sound like 4 strokes.

phil c:
building a sturdy, reliable reduction setup to a weight is hard.  You'll notice many have come and gone over the years in the RC world.   Almost always a small motor with a reduction gear is heavier than just simply using a larger motor.

Detune an ST91 or OS 91 or get one of the super zoot ones with the crank cut for left hand rotation.  They all should swing a 16 in. prop for a scale ship.

RandySmith:
Gear reduction drives are not a good idea  and  do not work very well on our single cylinder  motors, (There is a lot of banging going on in there)
The motors  we  use  are  very  hard  on  metal gears  and I can tell you from first hand experience  they do not last long.
If you did something like this, it would be  better  to use a  belt drive, maybe use one of the tiny aramid fiber drive belts.
Or best solution  just use a mild timed BIG engine to turn the prop.

Randy

Navigation

[0] Message Index

[#] Next page