Motor and Propeller

There's only a minor issue to add regarding a pusher or puller scheme. In planes, a pusher one has the potential to go forward and hit the vehicle and/or occupants in case of failure. So, a puller is always safer, because it will just go forward. Ok, safer for the vehicle, bad for those not wise enough to keep (a good) distance. Dynamically, the puller is always more stable, has more undisturbed air as mentioned. But I'm used just to airplanes, so, ... , why don't you just try? Ah! Ok! A pusher will look better, I guess. So, go pushing!

Does anyone know why there are no pusher boats (airboats excepted)?

Cruise ships and some pleasure craft use, "Pods," that use propellers at the front of the pod. The pod itself can be steered (Rotated) to allow very exact steering.

Volvo markets a system. They use a joystick for control.

I've seen those systems used for docking and other close maneuvering, but not for primary propulsion.

GA!

Thanks Chris.

Do a search for Volve Penta IPS / Forward facing, swiveling system Lots of You Tube videos from various boat companies.

Have you never been to Florida everglades? There are 1000s of pusher boats....

Here is one for example:-

??? Virtually all boats have pusher props (if you are referring to the underwater props).

There are! Have a look, I prepared this one for the kids earlier.

The cage was to pick up a propeller engine but the girls in the team convinced the petrol head that less can be more. It ended up being a space for a beach ball. In the surf it would be pushed by waves coming from behind and by this, the tip would be raised.

In a road situation I think pulling could be an advantage but weight distribution would come into it, I think. Experimenting would be on my cards.

Have fun, Ky.

I'm not sure I understand your question.

Nearly all small boats are pushers. The prop is at the rear of the hull, below the keel. Most larger vessels also have props at the rear.

Interestingly, I came across this beauty today, while browsing the web...

but as I consider my own fan powered roadable craft, I think that the air flow causes turbulence for the vehicles following it.

Chris

Nice. I suppose it's just like a little RC hovercraft with proper hulls. I think a full sized fan powered car would be a great idea. Mine is only a model and is only A3. I hate to think what the price of it all would be though, mine is already costing me £50 for a decent motor and RC system etc. If it were full size you wouldn't have the RC system but would probably find some other costs. Try making a dune buggy sort of thing.

Check out the cost of using a motor off a hand held brush cutter. They have strong crank shafts and with a bit of tuning, ie inlet port, exhaust porting and a tuned exhaust they put out good power and are very reliable, specially off a STIHL brush cutter or weed eater. Over here the RC Model shops are very expensive.

I don't know how you are steering, mine worked best with front wheel steering and an angled rudder to provide high speed cornering stability. You are also going to learn all about gyroscopic precession.......quickly. And like a hovercraft you will find that the braking from the prop is virtually non existent. So you will need brakes as well. Mine did about 65mph and made a big enough dent in the side of my dad's Dodge for him to notice and.....take corrective action against my backside!

Building and sorting out my R/C and full scale Hovercrafts was a lot less hassle than the darn prop driven car. So good luck and happy engineering.

Getting old....

Go with pusher, less thrust but better control, you want cleanest air off the prop against the rudders. Also install a good size cowling around the prop with vanes to straighten the air as much as possible. A swirling wash off the prop wrecks any handling you may dream of achieving. I also sacrificed weight and installed bigger battery pack for the R/C as low as possible to help compensate for the high centre of gravity the prop motor causes. My mate who built off my mistakes installed his motor low in the chassis and used a little toothed belt to drive the prop. (Off his mother's vacuum cleaner) Have fun!

PS. Of all the things I built, that darn car got me into the most trouble with everybody of authority within a two mile radius!!

Why do you want to use a propeller on a car. This is most inefficient.

In France about 70 years ago they were made, but even for thoise times too inefficient!!!

Andy if I had not had so much fun annoying my parents with mine , I would support you comment. This was my best-est-est makes no logic adolescent project that made a lot of noise and at my command on the joystick did exactly as it liked. That sir, is all the reason you need to do it.

OK!

Hi Bondy111,

A tractor propeller location will have the advantage of clean air for the propeller, but the overriding disadvantage of high forward thrust line. A more practical location is at the rear of the 2nd axle where the thrust line will tend to keep the front axle planted on the ground for better vehicle control.

Regards,

Luther M

You are using air as a reaction mass so you have to use newtons third law.

GA!

on another note, I have question... If turbo fans use many blades in a ducted propeller configuration, why do we not see piston powered many-blade propellers? and maybe have a slim duct integral, attached, and rotating with the blades?

similar to the following (engine fan and coooling fan)

thank you.

GA. Thanks

GA

in your case a ducted fan PUSHING would be more efficient, but frankly with a car, having the motor drive the wheels rather then a propeller would be even more efficient. I do not know wether you are building a full size car or a model, if a model I suggest going to some of the model vendor sites such as Hobby Lobby or Hobby People and see what they offer ( if a full size vehicle you are more or less on your own I can't help you there but frankly, you are going to get a lot more efficiency and control having the motor drive the wheels rather then using a propellor )

shows the experimental Bennie Railplane.

Nice!

my gut says pulling from the front lends better straight-line motion (horse/carriage). Pulling would also produce additional drag on vehicle. A pusher prop will be faster but possibly unstable.

shade tree