ParkHawk Motors

[BillBird]

Originally posted by Shawn Palmer
Ed,

Will you have your PH out @ the fly-in tomorrow?

Jim and I are planning to come down and play, It'd be nice to see it since I'm considering getting one.

anyone tried BL in one yet? (H~L 280size or baby Hacker?)

Shawn Palmer
RC Groups Sales/Marketing Mgr.

I was thinking about using the new AXI MINI AC1215/16 with a Carbon Fiber Case. Its supposed to have Speed 400 power with Speed 280 Size and weight. Its a brushless so i'm thinkng I might be able to get longer run times with the right Pinion gear. I don't know what pinion gear to use since I can't use Motor/prop charts. I think the main final gear runs at about 360 RPM (6 Flap cycles/sec) at max. power.

The AC1215/16 has a 3,800 RPM/V spec. and is made for 6-8 Cells and its max efficiency (79%) is between 5-10 AMPs.

The SPEED 300 that comes with the ParkHawk is rated at 6V but in the ParkHawk it is running over rated voltage so it can't be running very efficient.

[hvberk]

The "6v" is just a label from the marketting department.

A motor does not have a "voltage", but only limits:
- Too much RPM that it mechnically fails (voltage)
- Too much heat it burns. (total power)
- Too much current for the brushes to handle. (current)

All this for the desired lifetime.
Some people are quite happy to use the sp300 at 8 cells an 10A, although this burns up the motor in 10, 20 (maybe more if you prepped your motor) flights.
Efficiency and lifetime endurance are not the same.
Most motors are killed by too much current, not voltage.

In general, efficiency actually gets better with higher volgtage when you keep the current the same or lower.

[eflyer1234]

If you are considering changing the motor....

There are a couple of things to keep in mind. This bird flies because of the kv rating of the motor in association with the voltage. In English, this bird flys because of the number of revolutions of the motor. If you want good performance, you must shoot for a simular number of revolutions.

That said, some other motors that may work well on the bird are;

Simprop speed 300
GWS EPS 300C
Jamara Pro 280
Kyosho Lemans DCM20BB
Hacker B40 9S

Others have the ratings but start getting too heavy. Any change to the motor drive system of course is at the owners own risk.

-Jeffrey

[BillBird]

Thank you for the excellent information!

Is the number of revolutions required due to the motor acting like a fly wheel to carry the drive train through to the next power cycle of a Flap?

If your fly wheel weight (ie the motor rotating inertia) is too light in relation to number of RPMs then it won't carry the drive train to the next power cycle as effectively. A very finely tuned machine...

Sounds like a much different way of thinking than electric prop planes.

There is much to discover and learn about this new type of R/C flying.....

[BillBird]

Would the Hacker B20-12L work:?

Hacker B20-12L
kv - 4629 (RPM/V)
Wt. - 58g

It does look like the Graupner Sp300 #3306
With:
kv - 5660(RPM/V) Latest test data
Wt. - 51g

As listed at:
http://www.slkelectronics.com/ecalc/graupner.htm

has the best RPM/V for the money and the weight.

It would be nice to find a lighter brushless version of the Speed 300 with better (RPM/V) Specs.

I found a motor that might fit the bill:

Lehner Motors supposedly have a super high RPM/V range.
I found these at:
http://www.rumrunnerhobbies.com/10_series.htm
Seems like I should be able to spec out a super light weight 40g Brushless Motor that has a (RPM/V) Rating of upto 9231.

Looks like the 1010/19 Lehner Brushless motor with an (RPM/V) of 6319 might work. My thinking is that the lighter weight might necessitate a higher RPM at least in the non-power flap cycle.

I am not sure about the armiture weight of the speed 300?

The site motor calulator recommended a 1010/21 at 8.8V for 49810 operating rpm (8.8vx Speed300 5660) @ 8amps
Optimize for RPM.

Could opt for the 1015/15 model which is 50g?

[BillBird]

After looking at some of the specs for Lehner motors it seems like they are specifying the RPM/V value using a Delta Configuration instead of a wye configuration since they can be hooked up either way. This gives the impression that they are rated at a higher RPM/V but at what efficiency price?

Does any one out there know wether Lehner specs their motors using a delta configuration instead of a wye config?

[BillBird]

Originally posted by eflyer1234
If you are considering changing the motor....

There are a couple of things to keep in mind. This bird flies because of the kv rating of the motor in association with the voltage. In English, this bird flys because of the number of revolutions of the motor. If you want good performance, you must shoot for a simular number of revolutions.

That said, some other motors that may work well on the bird are;

Simprop speed 300
GWS EPS 300C
Jamara Pro 280
Kyosho Lemans DCM20BB
Hacker B40 9S

Others have the ratings but start getting too heavy. Any change to the motor drive system of course is at the owners own risk.

-Jeffrey

I was wondering if you had recommendations for a Brushless motor thats lighter than the Hacker. The motor you list here is over twice the weight of the Speed 300. Can you use a larger pinion gear on the motor or is it very sensitive to the moment of inertia of the rotating motor weight at RPM instead of a constant motor torque?