Hi Howard,
I am EXPERIMENTING with the motors and batteries combinations for my plane.
The Plettenberg Orbit 15-20 is too light having in mind the length of the nose of MP Bee.

I will use it anyway just to test the flight performance but, with 6S and 5S, it will need extra lead weight at the tip of the nose.
This is exactly what I had to do having Cobra 3515/18...I added more than 1.8 oz. of lead to avoid hunting.

This extra lead weight, needed to keep the C.G where it is with MVVS, will effectively make the entire exercise redundant.

Simply put: To use EFFECTIVELY Plettenberg Orbit 15-20 and 5S TP, I need a model with LONGER nose - like the original Igor's Max Bee I am building.

I will let you and everybody else know how the flight tests with Cobra, Pletty and, possibly, also AXI F2B went.

Cheers,
M

I am EXPERIMENTING with the motors and batteries combinations for my plane.
The Plettenberg Orbit 15-20 is too light having in mind the length of the nose of MP Bee.

I will use it anyway just to test the flight performance but, with 6S and 5S, it will need extra lead weight at the tip of the nose.
This is exactly what I had to do having Cobra 3515/18...I added more than 1.8 oz. of lead to avoid hunting.

This extra lead weight, needed to keep the C.G where it is with MVVS, will effectively make the entire exercise redundant.

Now there's ballast!

Hello Matt,

I can understand Pascal's response to some extent. BTW: Was it Pascal Meyer from Plettenberg in Baunatal, Germany?

When I still flew my Kontronik Kora15-16, also a very compact, very light-weight and high-end motor, I looked at attached graph and saw that at 11,000 rpm the motor would easily do its job and not overheat. You see that with more rpm the higher the power can be. This motor had an integrated fan, very comparable to the Orbit 15 Heli Expert that was recommended by Plettenberg to me but which I never purchased. With more rpm, the cooling increases and you can load the motor better.
So I would say that it rather depends on your target prop and target rpm and of course how it is cooled.

Christoph

.

Orbit Heli Expert motors have too high Kv. Nobody will competitively fly the full size F2B plane with motors having 1300-1555 Kv.

Regards,
M

You can get the cooling fan put on any of the 15 series motors.
You can buy the motors in Canada from Icare. (They have to order from Germany, so there is some wait time)
http://www.icare-icarus.com/
email Etienne with your request ( front shaft/back shaft/ wind/ cooling fan)

Well, Matt, I am not surprised they are silent. First of all they had company holidays. Second I also often do not know what to answer you, since your questions usually contain "your" answer, so maybe that was why they answered that is "does not work" :- ))

Actually it does and I wrote you in mail why you _I think_ you what you got, because I know our way of flight, while they do not have any clue what you do :- )))

So I will write it also here,

Spin DOES store maximal current. However that current is based on "some" resistance inside the ESC, so you cannot expect 0.5% precision. The current is measured really as MAXIMAL current, not as maximum from flight. It means Spin stores that current in case that ESC runs for some time for full throttle, and that is something we do not do normally since we have governor which should not go to maximal throttle.

RPM is also measured and stored. You wrote me that it was larger than maximum set in ESC, I wrote you that there is PID which can have overshooting. Plus MAX and MIN has some "atomization" so it can easily be that real max during work is some % more than what you set as parameter.

It works to some extent, but it is not mentioned to measuring device, it is tool for troubleshooting, not for power analyze.

I am happy that they make those ESCs for us (only for us) as they make money on something else than C/L flyers and currently I am waiting for new box (because they have really lot of work after holidays), so I am not surprise about answer "forget it, does not work" or simply silent :-  ))))))

Hello,
I have promised the comparison of the pitching moment of inertia for different motors and batteries and the first comparison is presented below.

My latest assumption was that the changes in the Pitching Moment of Inertia (PMI) caused by using the motors and batteries having different weights, must be calculated considering the PMI of the entire, RTF, model.

My tests show that this assumption was correct.

Configuration 1: MVVS 8.0 Kv=680, weight 228 grams and 6S ThunderPower 2800 mAh battery, weight 362 grams with EC3 connector.

Configuration 2: Cobra 3520/12 Kv=820, weight 216 grams and 5S ThunderPower 2800 mAh battery, weight 302 grams with EC3 connector.

The attached shows the details. The prop., spinner and prop. adapter were the same in both cases.

Red wide arrow: unchanged location of the C.G.
Blue wide arrow: 6S C.G.
Green arrow: 5S C.G.

The formula used: I (PMI)=(m x g x L x T^2) / 4x PI^2 where:
m=mass of the RTF model (1.844 and 1.774 Kg. respectively)
g= earth gravity (9.81 m/s^2)
L=distance from the point of suspension (please see the explanation below) to the RTF model C.G. = 1.47 m.
T=period of small oscillations in seconds (please see the explanation below).

After repeating the tests five times for each configuration and averaging, the PMI for the configuration 1 is
4.6050 kg x m^2 and for the configuration 2, 4.1730 kg x m^2.

Explanation: MPBee has been hung using the piece of string in such a way that the entire hanging model became the inertial pendulum with the nose pointing down. Small oscillations mean the amplitude of less than 3" what makes the sin ALPHA =~ ALPHA. The effect of aerodynamic drag was the same in both cases and is, therefore, irrelevant.

After using the Steiner's rule, the PMI about the model's C.G is 0.625 kg x m^2  for the first and 0.622 kg x m^2 for the second configuration.

This simply means that the corners will be the same in both cases, assuming of course the same input.

Happy Flying,
M