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Technical Reports Contra Drive Rotating System of Brenner Sharp Since fall 2011 the Contra Drive Rotating System of Mechanical Set Up A Contra Drive Rotating System consists of a spinner and two propellers. One of the propellers rotates to the right the other one to the left. Therefore the resulting sum of torque of the propellers is nearly zero. No right and down thrust is needed.
Figure 1: The installed Contra Drive Rotating System The two propellers are linked via a special gear, so that they can rotate independent of each other. This avoids vibration effects and leads to a high efficiency of the complete engine. The system is designed for Hacker- or Neu-Motors. Special adapters are available. There are 3 different types of gear boxes and several different sizes for the front and rear propeller available. This leads to a lot of different setups and allows adjusting the setting to the personal way of flying. In case of maintenance or repair a very detailed description is attached, so that a Do-It-Yourself action is possible. Every spare part can be ordered and is received in Overall, for design adjustment, several different coloured anodized Spinners are available. Flying The most important advantage of this system is the decelerating effect in the downwards passages in F3A programmes. It is possible to fly slower and with a perfect constant speed. The energy efficiency is high, a windy F13 program needs a recharging capacity of about 3.1 Ah with a 10S battery. Summary Over all the Contra Drive Rotating System of
Figure 2: The new Wind S Pro Full Composite with a Foil Design by Kalligraph
New LiPo Top Fuel 3800 Eco X from Hacker Motor About four weeks ago I got the new LiPo Cells Top Fuel 3800 Eco X from Hacker.
Figure 1: Top Fuel 3800 Eco X After assembling the two 5S packs to one 10s (stick form) the cells were formatted by charging and discharge them (down to 33V), in both cases with 2.5A. The new cells were compared with Top Fuel 4000 Light, because of similar capacity and application. The values found for 10S each are shown Table 1.
Table 1: Technical Data
Capacity value was measured by discharging down to 33V. The inner resistance was measured shortly after the cells were completely charged, that means immediately after the charger Schulze isl 8-936g stopped. For this measurement a Robbe Ri-Meter was used.
Concerning weight, this 10S stick shape packs might be a little bit heavier than two 5S side by side mounted packs.
All values in table 1 are averaged over two sets of both types and over several measurements.
Conclusions:
Both types have almost the same capacity at low current.
The higher inner resistance of the ECO X series is due to the lower weight and was expected because the 4000 Light are 30C and the 3800 Eco X are 20C. But the value of 19.4 mΩ is still a very good one for a 10S of that capacity and was expected to be more than good enough for the planned F3A application.
During flight tests, that means in P-13 or F-13, no significant difference between the two types could be notified, with the restriction, that the 4000 Light had already 50 flights each more than the 3800 Eco X.
Capacity seems to be sufficient with the engine I’m using (Brenner Sharp Contra Drive with Hacker C50XL Competition). After a strong wind F13 program 3.1 Ah had to be recharged, with 4A current and the mentioned charger.
So for low current applications like F3A the 3800 Eco X is the cell of choice, because of the good performance and the low weight.
Above all price is competitive.
A report about Cycle Stability will follow, as soon as there is more experience.
Table 1: Measured Values
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