Speed,Combat,Scale,Racing > Speed Talk

Electric Speed Rules

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Mike Palko:
If anyone is interested here are the 2007 electric A speed and B speed rules. I posted them in the electric forum also, but you might miss them because they are buried in a thread.

3. Control Line.
3.1. General Specifications. The use of gear boxes and multiple motors
is permitted. Folding props are not permitted. No electrical power may
be transmitted through the control lines. The use of radio control is
not permitted. All applicable sections of Control Line General and
Control Line Speed shall govern model and line construction and the
timing of flights. There shall be no loading requirements for Electric
Speed models.
3.2. Class A Control Line Speed
For event 606.
Any motor(s) allowed but the battery pack is limited to a maximum of 8.4
volts nominal of any battery type.
The model must successfully pass a 25G pull test prior to flight.
The flight speed will be calculated based on the ten (10) laps of the
circuit following three complete laps in the pylon.
Two (2) control lines, solid steel, shall be used and they shall be 42
feet long. Multistrand lines are not permitted. The minimum diameter of
each line shall be .012 inches.
The CD will determine whether hand launches are permitted.
3.3. Class B Control Line Speed
For event 607.
Any motor(s) allowed with the battery pack limited to a maximum of 42
volts nominal of any battery type.
The model must successfully pass a 25G pull test prior to flight.
The pair of solid steel control lines must be at least .018 inches in
diameter and not shorter than 60 feet in length. Multistrand lines are
not permitted. Maximum weight shall be 60 oz.
Flight speed will be calculated based on seven (7) laps of the circuit
following three (3) complete laps in the pylon.
The CD will determine whether hand launches are permitted.

dynasoar1948:
Mike,

Again, the AMA site, which claims to present present rules, still shows NiCad only for the  electric CL Speed classes.  I am right at the "assemble the battery pack" phase of building my new B Speed ship and guess I'll have to call AMA and try to find someone to clarify the situation.

As background, my present setup uses 18 1100Ma SCR cells to drive an Aveox 1415/2Y BDC motor thru an early commutation module, which has proven to be the weak link in the system.  The flight prop is a wood 8/8 Tornado copy and turns about 20500 RPM early in the flight. (This prop would wipe out the FETs in the commutation module unless unloaded in flight, as I learned to my cost.)  The weight comes in at 59.5 Oz, and 8-inches of prop diameter are necessary to match aircraft drag and provide for reasonable acceleration on the dolly. 8-inch pitch is a perfect match to motor loading.  I don't have my notes within reach, so estimate that, using a cut-down prop for static testing, this RPM draws about 86 Amp.  Early laps are about 125MPH, with the 7-lap AMA record 119.63 MPH.

The switch to other than NiCads (I have to buy new cells anyway, for a competition battery, since the NiCads I'm now working with are the best of my old ones, to make a battery for flight testing and early contests)

I'm open to suggestions re new cell types for this application, to duplicate an unpushed 18 cell NiCad battery (I time it out after 36 seconds) to use the same commutation module or alternativly, with a new module, the maximum that can be packed into a 30-32 Oz battery.

Will Stewart

Mike Palko:
Will, Here is my response from the electric forum.

   Since I'm toying with the idea of building a speed ship, I contacted the AMA about any future rule changes so I don't build an obsolete airplane/power system. Steve Kaluf replied with the following rules for 2007. He said the AMA web site should be updated by the 18th or 19th of January, but I guess they are a little behind.
 

   If you want some suggestions on batteries I would be glad to help. NiCd's are ancient technology in the R/C world. NiMH cells are still pretty hot and new cells are being developed about every 6months. For the best performance (see most expensive) you can use Li-Poly cells.

   For me it's a toss up between NiMH cells and Li-Poly cells. I haven't flown enough speed events to know what saving a few ounces will do for performance. Also, the fact that I would only fly the airplane a few times a year makes me want to stick with NiMH cells. At least for now......

   Thanks for the info on your power system. BTW did you get my PM?

dynasoar1948:
Hi Mike,

Read your PM and will look thru my files for photos or sketches that may be helpful.

About cell type:  Looked briefly at LiPo, LiIon and LiManganese, and was deterred by price and need to obtain a new charger.

The remaining unknown tonight is whether NiMh offers any advantage over old fashioned NiCd in my nearly completed new ship. Since I'm limited to the existing old style Aveox commutation module, and would be out of business if I smoked it, I'm proceeding with caution. (If anyone has a source for early Aveox modules, please let me know.) Since I don't dare increase voltage, the battery characteristics I'd like to get are decreased weight and/or less voltage dropoff during the 30 sec run.

I believe that my new ship should handle and groove far better than my now retired high pitching moment "Flying Pencil".  Am looking for about 130MPH, which would mandate an increase in line diameter to 0.020-inch.

Mike Palko:
Hey Will,
   I think you will see a performance increase by switching to NiMH cells, especially if your cells are getting old. NiMH cells will also offer a few other advantages like little to no memory, slightly higher energy density and the fact that they are still available...... I don't think 1000mah SCR NiCds are made anymore?

   To give you an idea of what is available in your weight range I will list a few.

1) GP2200 2200mah 1.62oz and measure 1.32" long x .89" dia.

2) GP2000AFHR 2000mah 1.23oz and measure 1.68" long x .66" dia

3) Elite1500A 1500mah .81oz and measure 1.13" long x .66" dia.

   I also listed them in order of performance. As a rule of thumb the larger the cell the higher the voltage will be under load. I couldn't find any specs on the 1100SCR cells so I couldn't directly compare them to the NiMH cells I listed. I would imagine the 1100mah cells you are using now, must be taking a beating (80C discharge). The voltage drop under load must be pretty high. How many cycles do you have on them? How do you feel the performance is compared to when new? 

   You can always go with what you have (batteries) and upgrade later if you are not satisfied with the changes you already made.

   

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