oly_rcer

okay so i've been racing rc trucks and now am trying to fly had a hbk2 and have a trex just bought an estarter to learn how to fly the question i have is i want to go brushless with it but i'm looking at the gearbox and motor.notice that the pinion gear is pressed on and on the motor screws there is no room for adjustment(damn big pinion too)oh yeah its a 400 stock brushed motor that came with it.
so what size motor would be a good fit and any ideas on the pinion gear?thx
oly

AJ1202

Oly when going brushless you will get rid of the gearbox. What you want is a 950 to 1200 KV brushless motor, this way you can swing a prop about the same size a 9X4 or 10X3.8 works great on the ES. one thing your going to find is the ES will come out tailheavy when finished and going BL makes it worse, you will need to pay attention to that and correct it before you try to fly. The ES is a great trainer and a fantastic flying plane, it also can be modded into a much better performing plane later down the road. Make sure you use a CF rod or tube in the wing and go farther out with your spar than in the original build. Also running a thin CF rod inside the fuse from the rear of the cockpit to the tail is a good idea as the tail section is a weak point of the plane.
On mine I built a lite ply firewall to mount the motor, the first bl motor I used had a stick mount so I just used the factory stick mount untill I broke it in a crash, personaly I like the firewall setup better
If your going lipo cut your battery bay all the way to the LG mount and move the batt forward, this will help reduce or eliminate the need for ballast weight in the nose to get CG
Good Luck and I think you will be happy with your new plane

oly_rcer

thx that helps a bit so any idea wha
t rpms these props should turn?

ozrcboy

It depends...

A lot of pretty complicated physics governs how props work but here are some of the basics. If you know the RPM the prop spins at (by measuring with a tachometer, or estimating) you can calculate a pitch speed. So, if your prop turns at 10,000rpm and it is say, an 8x6 (where 6 is the pitch in inches) then you have a pitch speed of 60,000 (6x10000) inches per minute.

Your aircraft is never going to fly faster than pitch speed (well, perhaps in a steep dive) but basically not.

Then you have thrust... your aircraft can't fly any faster once aerodynamic drag overcomes thrust - you've reached an equilibirum point.

Wide diametre (the first number, so 8 inches from the example above) props tend to produce lots of thrust, smaller props tend to produce more pitch speed, with a middle ground between thrust and pitch speed.

Getting the right prop for you model is about:
- Choosing a prop that, when teamed with your motor, draws amps within the system limits
- Suits the style of flying for the model. For a 3d or ultimate bipe, a wide slow flyer prop for lots of thrust. For a warbird, a compromise prop, favouring pitch speed just slightly, for a hotliner, or pylon racer - pitch speed (and a very sleek aerodynamic model).

You might find this useful/interesting:
http://www.oz********.com/2007/05/un...-electric.html