Well since I should be getting my hulls some time in the next month I should be looking at a radio. I do plan to make a submarine or two so I want to get a 75MHz before they go the way of the Dodo. The 2.4 do not penetrate the water for use in submarines. So I was looking at the Hitec Laser 6.. www.trossenrobotics.com/hitec-laser...ystem.aspx It states that the 3rd channel has end point adjustment. Could that be the throttle adjustment? I figured it would be better to get the 6 channel coming out of the gates.. for 134 sounds like a good deal. So should I go and do it then?
you might consider trolling rcgroups for a used eclipse 7, as sometimes the extra channels can come in handy. I sold mine last summer for 50$.
Does 2.4 GHz really not penetrate the water? Just curious...I was thinking about getting one of them for all my projects (including a finished submarine)
Hello, My Futaba CAP9 will not work with my ship under less than two feet of water standing less than six feet away. I put the Fasst 2.4 conversion module on my CAP9 which was originally on 75. Other brands of radios on 75 may have 2.4 modules that can be added that way you could switch back to 75 for your sub. RiverRaider
2.4 definately does not penetrate water well. For submarine use, you definitely want to go with an HF band radio. For any other surface use, I would highly recommend 2.4 ghz. IRT the fasst module for your CAP9, do you have any more information on this? I have a skysport 6 that I LOVE and would gladly convert it to 2.4 ghz. I already have 1 fasst radio (which I also love), but prefer the "feel" of my old skysport 6.
Hmm that's interesting. David Merriman recommends teh 2.4ghz radios for the subs. He's dive tested his subs to 5 and 10 ft with no issues penetrating the water. I'm using a Futaba 2.4ghz for my Gato and Seaview.
According to the following article: http://en.wikipedia.org/wiki/IEEE_802.11 "The other major factor in performance is absorption by water and moisture. 2.4GHz is very close to the O-H bond frequency. Water is full of O-H bonds so it tends to really absorb 2.4GHz WiFi signals. Higher and lower frequencies have less of a problem with this." Also, your radio choice is important: http://www.stevenswater.com/telemetry_com/spectrum_info.aspx IIRC, the Spektrum radios use DSSS, while the Futabas use FHSS. FHSS would have better penetration characteristics, so you can't assume that all 2.4's will be equal. Another thing to remember is that the Navy uses VLF (Very Low Frequency) to communicate with submarines...because lower frequencies have better water penetration characteristics. HF radios are FAR lower then the microwave 2.4 radios (S-band). While I was in the Military, I spent some time doing airborne radar imagery (ARL-M platform), and when I got out, I worked for the company who built the planes as a trainer/technical writer. I've shot a lot of radar images with both Ku and X band radars, and my experience with how microwave RF tends to interact with water makes me a bit leery about trying to use a microwave radio in a sub. I'd by far trust HF technology over microwave for that use.
How does it work for fresh water? I know Salt water reduces the signal significantly but what about fresh water?
I'd imagine there is little to no noticeable difference between fresh and salt water. He's a blurb from the following site which gives the basics of the standard RF ranges: (http://www.astahost.com/info.php/Frequency-Types_t633.html) It's been a long, long time since my RF theory class, but it essentially looks correct "A microwave oven uses a magnetron microwave generator to produce microwaves at a frequency of approximately 2.4 GHz for the purpose of cooking food. Microwaves cook food by causing molecules of water and other compounds to vibrate. The vibration creates heat which warms the food. Since organic matter is made up primarily of water, food is easily cooked by this method." While we aren't trying to cook food, the basic principle from how the RF and the water interact is the same. With our ships there is an awfully large amount of water for our transmitters' signals to cause to vibrate....which uses some of the energy from the RF, and impacts how deep the signal gets before it runs out of energy. With a surface ship this isnt a problem, because the ships get a clean signal from the air, before it has to start penetrating water. For a sub though, the signal has to punch through to the depth of the sub, while still maintaining enough energy to carry it's signal....while the medium, water, USES the energy of the original signal from the transmitter.
Thats interesting... I had heard about the UHF transmitters the navy uses but I didn't realize all that about the microwaves. Would it be better to get a new Futaba set or an old fashioned FM radio and just change the crystals?
2.4 is great if you are running a surface ship, no reason to not use it. It's only submarines or firing guns after the ship sinks (to create bubbles to locate the ship with) that might be problematic. I'm changing all my ships over to 2.4 ghz eventually, and don't plan on building any subs.
