Hi Guys,

I am new to the sport, thus the beginner post...

I started on a 4 CH motorized glider (400 brushed) last year. I think I have the hang of it and really enjoy it.
Last month I bought the VMAR Bird Dog ARF and i need some help setting it up.

It is 43 inches span, 29OZ. The recc motor is a 100-180 Watt Outrunner. I picked up a 178 Watt / 3800 RPM motor.

questions:

1. Only some engines that are forsale provide power in watts. How do I find a similar power engine with different ratings? Should I get less RPMs for this plane?

2. How do I select a good prop for this bird? I am thinking more power and time aloft than speed.

3. Radio question: when buying a radio does the receiver and TX have to be the same MHZ, then jsut swap crystals to change freq?

Looks like an interesting plane.

First, a couple of links, which you may find useful if you haven't seen them.

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=771]RC Universe Review[/link]
[link=http://www.wattflyer.com/forums/showthread.php?t=969]WattFlyer discussion thread[/link]

Your questions.
1. If the motor specs list maximum current (Amps) for the motor, you can easily figure watts. Power (watts) is current (Amps) multplied by voltage (Volts). Since you generally know what kind of battery you will be using (and therefore its voltage) multiply by the Amps specification of the motor to get watts.

Are you saying that your motor has a kV of 3800? That's much too high for direct drive on a plane of this type.

The actual RPM depends on which prop is used, but almost any motor suitable for this plane will have a kV much lower than 3800, but an actual RPM significantly greater than 3800. I haven't read the review or the discussion thread in detail. Perhaps they contain some discussion of the proper motor specs for this plane.

2. The RCU reviewer used a Master Airscrew 8 x 5 Narrow Electric Prop, which was apparently supplied with VMAR's power pack combo. I have no idea if that's really the best prop.

3. The receiver and transmitter must be the same MHz (megaHertz) and on the same channel number. A basic transmitter comes with a channel already assigned, and you can not change it without returning the transmitter for professional service. More elaborate synthesized transmitters can be moved to any channel. The channel of a receiver can be changed by changing its crystal.

Technology update! With a Spektrum 2.4 GHz radio system, you don't have to worry about channels. The transmitter and receiver automatically find unoccupied channels.

- Jeff

Thanks Jeff. Very helpful.
I'll keep the motor I have for a sport plane once I get more experience and move up in th eworld of RC flying.

For now, I just want a good high wing plane with good power, but easy to handle.

How do the specs on this motor sound?

Kv: 924rpm/v
Operating Current: 6A ~ 14A
Peak Current: 17A
Suggested prop: 11x5.5 E-prop
Suggested Battery: 1300~2200mAh 3S1P
Weight: 59g
Dimensions: 27.6 x 32mm
Shaft Size: 3.175mm

with an 1800 3cell battery.

Once again, its a 29oz Bird Dog, 43 inch span.
I'll have to see about a prop.