Altimeter Circuit Board measured only 1-1/2" long x 1" wide x 1/2" high and weighs just 12 grams.
|Sample Rate:||1 or 5/second|
|Recording Time:||up to 4.5 hours|
|Weight w/sep LiPo power supply:||18g|
|Accuracy:||within < 1 ft.|
|Computer Connection:||RS232 or USB|
|Power Supply Voltage:||3.3-10v|
|Stabilization Time at Boot-Up:||2 minutes|
|Available From:||Soaring Circuits|
If youíre like me Iím sure youíve wondered more than once just exactly how high your RC aircraft is. It doesnít matter if youíre flying a small little park flyer or a 4 meter scale sailplane Ė itís fun and informative to know what your altitude is. Well, now the answers are available.
This review is about the Recording Altimeter for Models, otherwise known as the RAM. It was designed and is produced by Soaring Circuits. The RAM system is much more than just an electronic altimeter. It is a complete hardware/software package. The system consists of the altimeter circuit board, a cable that connects between your computer and the altimeter, a CD containing the system software, plus a very complete set of instructions. Itís capable of logging a complete record of your flight, and can do so for over 4.5 hours!
You can then download this information to your computer using the supplied system software, FlightView. I found this software to be easy to use and an invaluable tool for testing different combinations of motor/battery/props, clearly helping to identify the combination that yields the optimum rate of climb.
When I first opened the package I was very pleasantly surprised at how small and light the RAM circuit board was.
Due to itís small size and weight it can be used in virtually any plane. I used it very successfully in everything from an ultra light Park Flyer and HLG (Hand Launch Gliders) up to large sailplanes. It worked great in every plane I tried it in.
Using an on board jumper, the user is able to change the number of sample rates to either 1 or 5 samples/second. I left the jumper in the 1 sample/second rate. This setting allowed me to achieve 4.5 hours of recording time. I saw no advantage to gathering 5 samples per second, although the option is there if someone wants to utilize it.
The manufacturer claims the altimeter resolution is accurate to less than 1 foot. This is based on the accuracy of the transducer used and there was no reason for me to doubt this.
The interface to the computer for data downloading is done using the supplied cable, which was in my case a RS-232 connection. Soaring Circuits is now also offering a USB connection.
One thing I was concerned about when I first received the unit was how much power the RAM would use. Since I had initially planned on powering it solely from my radio system battery, I didnít want to use a lot of battery powering the Altimeter. I was especially worried about this when I used it in the Cub, since the battery capacity of this plane was small. It turned out my worries were completely unnecessary.
I was very surprised to learn how little power the RAM consumes Ė typically less than 20ma. The power supply voltage can range anywhere from 3.3 to 10 volts. The RAM design uses low power/low voltage components that allow it to be powered by anything from a single LiPoly cell all the way up to a standard 9 volt battery. I used several different power sources as I tested the unit in multiple planes. All worked well.
To allow the RAM to easily be moved from plane to plane without having to disconnect the power connection, I eventually settled on a 170ma LiPO cell. This battery was capable of powering the it for over 6 hours, although I never tested it quite that long. In this configuration the complete airborne package weighed less than 18 grams!
I like new toys as much as anyone does - maybe even more than most. When I first received the RAM I was anxious to begin playing with it as quickly as possible. I had initially been interested in using the RAM primarily when I flew my sailplanes; however, after looking the package over for a few minutes I realized how quickly I could install it in my GWS Cub, walk down to the park and be in the air within a very short period of time. So I did just that.
The RAM fit easily in my GWS Cub. Itís wrapped in the supplied open cell foam. I used the system flight battery for power, plugging the RAM into an unused channel of the receiver. After powering it up and waiting the required 2 minutes for the transducer to stabilize, it beeped 3 times to let me know it was ready, and then once a second as it began collecting data. I hand launched my plane and off it went.
After flying around for awhile I returned home to upload and examine the flight data. It only took a few minutes to plug in the cable to an open RS-232 port on my computer and load the supplied system software. The installation couldnít have been much easier.
I found that downloading flight data to the FlightView software was extremely easy and intuitive.
Using the FlightView software was easy and fun. I could easily set cursors using a simple drag'n'drop to look at rate of climb and the time duration to achieve it. Using the available controls, it was easy to zoom in and out and pan left or right. Using the mouse, I could place a marker to show the altitude anywhere on the plot. All the data was there for me to evaluate.
I found one of the most powerful things for me personally was that once I had converted the altimeter to a stand-alone configuration using the LiPO cell for power, I just left the altimeter on all day. Once I got home I uploaded the data and had a wealth of information to review.
I next used it in a small hand launch glider. As shown in the picture below, the fuselage was narrow but I still managed to fit it in while still providing a wrap of foam around it for protection. I also faced the interface jack up so I could easily download the data without having to remove it. I flew the HLG a number of times with the RAM installed, and found the RAM to be very useful in evaluating my launches. Itís a great tool for reviewing launch techniques and what did and didnít work.
I should mention that with the RAM installed in the HLG I made a less than optimum ďlandingĒ. Some might even call it a crash. Probably most would, since it was inverted when it finally reached the ground. I was very relieved to find the RAM was completely undamaged. The plane, however, was not. Thank goodness I had wrapped it in the foam. Although I wouldnít recommend crash testing a RAM such as I did, it is important to note it survived a relatively violent crash unscathed.
Iíve found the RAM to not only be a great deal of fun to use but also a valuable tool in evaluating my flights. The performance of my planes and my launch techniques of both Hand and Winch Launch Gliders were easy to evaluate using FlightView. Although my primary reason for wanting an altimeter was to log my sailplane flights, Iíve been very pleasantly surprised to find I use it for much more.
The designer of the RAM shows how well thought out this product is in just about every way possible. It is very easy to install, and up and running in just minutes after first opening the package. In all the time I used it I never once experienced a single problem. It performed flawlessly for me throughout my testing, even after my ďcrashĒ landing.
The construction and soldering of the circuit board is very high quality, as is the system cable. The product is well thought out and easy to use. The software is easy to use and very intuitive. Itís versatile and allows the user to easily manipulate the data to examine either the entire recorded flight or just certain portions.
I feel the RAM package is an excellent value, especially considering itís low cost. Itís both fun to use and a serious tool to evaluate your planes performance. I would recommend it to anyone who desires to evaluate their flight data or just wants to know how high they fly.
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