Frequently Asked Questions - 2008/01
Bob Aberle | [email protected]
Hobby Lobby International's Balsa Stripper
Q329: “I recently read an article about a balsa stripper and like always, now I can’t find it. Can you help me out?”
A329: A balsa stripper allows you to cut sticks from sheet balsa. You could do this with a simple X-Acto knife and a steel straightedge, but a stripper can do the job more easily and accurately. One advantage to cutting your own sticks is that you can match the balsa’s hardness and grain. I’m sure there are several balsa strippers on the hobby market. The one I’m familiar with is the Balsa Stripper from Hobby Lobby International (item HLH625) that sells for $19.90. Spare blades for it are available for $1.50 each.
This tool can handle 36- and 48-inch lengths of balsa sheet up to 1/2 inch thick. It includes a 36-inch-long extruded-aluminum guide channel that assures a straight cut, even when the sheet-wood edges are irregular.
This stripper is a basic tool you should have in your shop. Even if you don’t scratch-build aircraft, it will prove to be a big help when you’re cutting wood to odd sizes to repair ARFs and RTFs.
Q330: Servo tester
Q330: “I recently placed an order with FMA Direct for one of their servo testers but was told that they were no longer selling this product. I understand that this tester had many special features that were desirable and wonder if you can furnish me with information on a comparable tester.”
A330: I’ve seen many servo testers offered through the years. They range from basic units that simply drive the servo without the need for the RC system to sophisticated and expensive testers with all kinds of features. Some of these units cost as much as a complete RC system.
When I want to try a servo to see if it works, that the gears aren’t worn, or that the resolution is acceptable, I use an available RC system. But for those who want a dedicated servo tester, there are still some on the market.
Vexa Control Inc. of Ocala, Florida, sells a ServoXciter EF, which the company claims is a precision servo driver and tester. It is a handheld device that costs a reasonable $69.95.
You can use the ServoXciter EF to test servos or break in new servos. It can allow you to set up control linkages in your aircraft for the first time. It is claimed to be able to verify receiver pulses and check for glitches. It can also check onboard battery voltages.
Also included in this column:
- Servo tester
- Voltage regulator
- Brushless-motor timing
- Follow-up to Velcro-tape convention (Q/A 302)
- Follow-up to converting from fuel to electric power (Q/A 314)
- Follow-up to plans-soaking idea (Q/A 317)
Q331: Voltage regulator
Q331: “I understand that there are regulator devices available on the hobby market that will reduce a higher airborne operating voltage down to a safe and usable level to operate an RC system. Why would I want to do this and where could I buy such a regulator?”
A331: A voltage regulator reduces a higher voltage level to a lower level to customize it for specific applications. The BEC circuits included in most current-day motor ESCs are essentially voltage regulators. You feed in something such as 7.0–12.0 volts on the battery end and the BEC provides a regulated 5.0-volt output to operate the RC system from the same battery pack.
But keep in mind that voltage regulators are also sold as stand-alone items. Their sole job is to reduce and regulate voltage.
Fromeco Scale Avionics LLC, the company that sells the popular TNC tachometer, also offers the Regulator. It is a small device, weighing just 1.2 ounces, and sells for $40.
The Regulator can handle input voltages up to 10.0 volts DC, so you can use a power source of five to seven NiMH or Ni-Cd cells or two Li-Poly cells. Either way, the regulated output can be adjusted between 4.9 and 6.2 volts and at current levels of up to 9 amps. Being able to adjust the output voltage is a real plus for this regulator.
The higher voltage will cause your servos to travel faster, while the converse is true as you get close to the 4.9-volt minimum. But the choice is yours to tailor the servo speed to exactly what you want for each particular aircraft. You can also use the regulator with a five-cell NiMH or Ni-Cd battery pack and still select the exact output voltage for your needs.
Because of the high current rating, this regulator can easily be used for giant-size model aircraft and large helicopters.
Q332: Brushless-motor timing
Q332: “I have noted in certain brushless motor literature that they can be ‘timed’ or adjusted to optimize performance. Outrunner type brushless motors seem to employ different timing than the in-runner variety. I’m curious about these motor adjustments and would like to find out more information.”
A332: Until recently the subject of brushless-motor timing has been somewhat limited and rather vague. Some people say that outrunner-type brushless motors need a “timing advance,” while inrunner motors prefer more of a “retarded” timing. I did a literature search and have come up with several references that might help you.
The company simply known as Air Craft, located in Japan and operated by David Radford, has an excellent DataSheet on the subject of brushless-motor timing. Although this info is specific to certain types of motors and ESCs, it is still extremely helpful.
I found another excellent reference in an article published in the August 2007 issue of Ampeer: the popular national electric-power newsletter that is edited by Ken Myers of Walled Lake, Michigan. Ampeer is sold by subscription for an annual fee of $10. I'm not sure if back issues or copies of that specific article are available, so you should ask Ken.
The September and October 2007 Ampeer issues contained excellent articles about selecting electric power systems, which is always important information for the electric-power flier.
Follow-Up to Q/A 302 (July 2007 MA, page 75)
It was suggested that when using Velcro hook-and-fastener tape you place the hook side on the battery pack and the "fuzzy" side on the aircraft. If all your fellow club members did the same, it would be easy to swap battery packs if the need arose.
Paul Thoms wrote in and indicated that he placed pieces of the hook side and the fuzzy side back to back and cemented them together. This essentially makes an adapter you can keep in your field kit.
With this suggestion it doesn't matter what your choice is for the hook or fastener (fuzzy) side. Just install the adapter between your battery pack and the aircraft. The slight extra thickness should not be any bother.
Follow-Up to Q/A 314 (September 2007 MA, pages 87–88)
I mentioned several manufacturer/distributors that offer help when you are converting a model from a fueled to an electric power system. They can also recommend electric power systems if you provide the size and estimated weight of your proposed aircraft.
As I suspected, many companies now provide this kind of service. I was recently informed that Hobby Lobby International's senior technical representative, L.A. Johnston, provides this same kind of service with regards to the company's product line of motors, ESCs, propellers, and batteries.
The conversion table I referenced in that Q/A was accidentally omitted during the editing process. A copy has since been published in MA. In case you didn't see it, please drop me an e-mail and I will reply immediately with an attachment of that table. My apologies for any inconvenience that may have caused.
Follow-Up to Q/A 317 (October 2007 MA, page 92)
Charlie Reich noted my suggestion of using mineral oil as a plans soaker to see the wing outline on the reverse side. He indicated that he has used another popular chemical to do the same job: WD-40 spray oil.
It is easy to use because it comes in a spray can and is readily available in all kinds of stores. It dries after a day or so and doesn't deteriorate the plans or paper in any way.
Now you have two ways of doing the same job!
Sources
- Balsa Stripper:
Hobby Lobby International (615) 373-1444 www.hobby-lobby.com/planer.htm
- Brushless-motor DataSheet:
Air Craft 81 948 21 1045 www.aircraft-world.com/prod_datasheets/ac-esc.htm (The character between "prod" and "datasheets" is an underline—not a space!)
- Brushless-motor timing reference:
Ampeer [email protected] (810) 679-3238
- Fuel-to-electric-power information:
L.A. Johnston [email protected]
- ServoXciter EF:
Vexa Control Inc. Box 830301 Ocala FL 34483 www.vexacontrol.com
- The Regulator:
Fromeco Scale Avionics LLC (503) 766-3261 www.fromeco.org/aregulators.htm
Transcribed from original scans by AI. Minor OCR errors may remain.
