Frequently Asked Questions - 2012/02
Add-on telemetry systems for onboard batteries
Bob Aberle | [email protected]
Please write in with your questions. That is the only way we can keep this column format going. When referring to previously published questions and answers (for follow-ups), always provide the number as a reference.
References to addresses and websites are placed in a group, separate from the text, at the end of this column under "Sources."
Another feature, "Tips," will be provided in addition to frequently asked questions. These tips will be numbered in the same sequence as the questions.
Q540
"I've seen references indicating that several new RC systems now include built-in telemetry devices. These units send signals from the model back down to the pilot holding the RC transmitter on the ground. Information such as onboard battery voltage can then be made available to the pilot while the aircraft is in flight. My RC system is several years old and does not have this kind of capability. Are there any add-on telemetry systems available that would benefit me?"
A540: I know of several such devices, or I should say, I've seen the advertisements for them. Some are available from the original equipment manufacturer and others are truly aftermarket (generic) devices. I saw one such add-on apparatus demonstrated at my local club field, so let me report on that particular system.
It is called the Quanum Telemetry System and is offered by Hobby King. The device includes both a transmitter that goes into the aircraft and a receiver that you attach to your RC transmitter (any type or brand). It sold for $49.99 as of October 2011. The Quanum (that's the way Hobby King spells it, but I think someone forgot the "T") provides real-time voltage, current, mAh, and temperature display information, as well as a low-voltage warning alarm. The display and alarm operate from the special receiver that you mount or attach to your RC transmitter. That receiver is self-powered by an internal 450 mAh Li-Ion battery, which you must charge separately from your transmitter. The large 132 x 64 mm LCD screen is easy to read.
The Quanum Telemetry System will warn you when your battery is approaching 3.2 volts per cell with a variable audio tone. This type of warning will help eliminate dead-stick landings. The radio link from the transmitter to the receiver is on 2.4 GHz DSSS, which claims not to interfere with your primary RC system.
In the photo that I included with this column, the individual cell voltages appear on the receiver screen. This results when you plug the onboard telemetry transmitter into the battery pack's node or balance connector. This will help determine if any particular cell is becoming unbalanced while the aircraft is in flight.
To obtain all the features of this system, you will need to purchase an optional current/temperature sensor, which also goes onboard your aircraft. That sensor cost $19.79.
I've flown this system and I'm impressed with the way it works. One thing I really liked is that I could use half my battery charge and land. Without recharging, I could make a second flight on the remaining charge before the warning alarm sounded. Would that feature interest you?
Q541
AMA member Jim Noffze wrote in and asked where he might find a source for scalelike canopies. His interest is in .40- to .61-size warbirds. These fighters require a decent canopy to look authentic, rather than being simulated with paint. His modeling friends indicated that he should make a plug and vacuum-form the canopies, but that takes craftsmanship and time to do the job correctly. Where can Jim find a source to purchase these canopies?
A541: I did some searching and networked with some of my Scale modeling friends. What I came up with surprised me.
There is an excellent source for scalelike canopies; they can be purchased from a company known as Park Flyer Plastics. The owner of this company is a well-known modeler by the name of Keith Sparks.
You have probably seen many of Keith's designs as construction articles in the various hobby publications. What surprised me were various scalelike items that Keith also sells. I found an entire series of dummy, plastic-molded radial engines. He has painted pilot heads or busts, molded plastic wheel pants, and a selection of 23 model kits with foam and balsa construction. Visit Keith's site and familiarize yourself with his product line.
Tom Hunt published an interesting how-to article on scalelike canopies in the August 2008 Fly RC magazine. The subject of this article was how to dress up your scalelike canopies. In that article, Tom shows how to add detail to a basic vacuum-formed canopy for added realism.
Q542
"I seem to have a heck of a time adding trim to my iron-on covered models. No matter what I do, I get air bubbles between the two layers of covering. I heard that you can use a solvent to add trim pieces without the need for heat. What is that all about?"
A542: Many iron-on covering suppliers offer solvents that let you apply trim pieces of covering material on top of the surface that you have already covered, without the need for heat. These solvents come under many different names, but Jim Minadeo of BP Hobbies told me that the basic trim solvent you need is plain old acetone, which you can find at almost any paint or hardware store.
As soon as I heard this suggestion, I made up a test piece to try it. I covered a piece of balsa sheet using my heat iron. Then I cut out trim strips from a different colored covering material. I wiped the acetone onto the covered surface and applied the trim strip on top of it. I gave the trim and the covering one more wipe of acetone and let it set for a while. To be sure that the trim stayed in place, I applied some heat to the end joints.
The result was a smooth surface free of air bubbles. Best of all, the trim ended up exactly where I wanted it.
Q543
My thanks to Canadian modeler and prolific designer Chris Moes for sharing with me a wonderful, free plans service. The service is known as Outerzone and it originates in the United Kingdom. The site lists more than 1,500 model aircraft plans. You can download any one you like into a PDF file and take it to a printing service such as Staples or FedEx Kinko's and have your plans run off at any size you desire.
There are many types of aircraft, including Vintage RC, Old-Timers, Free Flight (FF), Scale, and rubber-powered models. I found it thrilling to read through the list. Do yourself a favor and check out this site. My thanks to you, Chris!
Q544
"Bob, you were kind enough to send me your listing of all your published designs that you referred to in your August 2011 MA column (QS10). As I was reading through your list, I noted a single RC boat. Did I read that correctly? What was that all about?"
A544: In the late 1970s, longtime modeler Bob Kress developed a ducted-fan system using high-powered, glow-fueled engines, along with specially designed multibladed fans. The fans ran inside a duct or tube.
Bob named the system the Axiflo and created a company to market it, known for many years as Kress Jets, Inc. Bob was an MIT graduate, a Grumman vice president, and one of the principal designers of the Grumman F-14 Tomcat.
At the time, Bob asked me to try out one of the prototype Axiflo ducted fans using a K&B .40 Schnuerle-ported racing engine. I didn't have time to build an airplane for this system, but I did come up with an alternative.
I fashioned a foam surfboard available from Walmart into a boat that I named the Aqui-Duct. It turned out to be more successful than any of us expected. I placed the Axiflo on top of the foam surfboard toward the rear. Behind the duct I arranged a rudder and elevator using RC control.
As I remember, the elevator wasn't effective (it wasn't an aircraft), and the rudder needed more area, but once I enlarged it with the ducted fan passing wind-tunnel-velocity air on the rudder, steering control was very effective.
Nick Ziroli Sr. and I ran the Aqui-Duct at the big Lake Ronkonkoma on Long Island. It moved fast and was fun to operate.
The thought now comes to mind that this boat concept might work today with electric ducted-fan units. There are many now available. I'm sure these foam surfboards are still available as well, but you could cut one out of 1-, 2-, or 3-inch foam slabs.
The original plans for the Aqui-Duct are still available from Carstens Publications as Plan No. CB-11. The construction article for this boat appeared in the January 1979 Flying Models. I hope my readers won't mind this one departure from aircraft into the marine world.
MA
Sources
- Hobby King
(800) 607-5803 www.bit.ly/tz2Pw6
- Park Flyer Plastics
(817) 233-1215 www.parkflyerplastics.com
- August 2008 Fly RC article
- Outerzone
[email protected] www.outerzone.co.uk/index.asp
- Carstens Plans Catalog — Aqui-Duct Plan No. CB-11
(888) 526-5365 www.flying-models.com/catalog/pdf/RCCComplete2011.pdf
Transcribed from original scans by AI. Minor OCR errors may remain.
