I am getting back into RC gliders after almost 17-18yrs. My first was the Sophisticated Lady (T-Tail Goldberg - they apparently quit making that kit)... (she died a horrible death when flying in less than ideal wind conditions) so, my next endeavor is the Gentle Lady. I have everything done except covering it and final tail section (tail, stabilizer etc...). I won't have a lot of time to devote to this, but, will give me an alternate outlet - other than the many computers I have in my basement.
In preparation for a really nice, calm day, I would like to order the radio. I am looking at a 6CH 72Mhz Futaba - like the LXRXF6. Yeah, I only need 2 for the glider (well maybe 4 - for when I add those booster rockets :) ). I don't want to spend an arm and a leg, but also want to get something descent should I want to try something a bit more challenging (like maybe a A10 inducted-fan or something :))
I suggest that you look into a 2.4 Ghz radio instead of 72 Mhz. 2.4 Ghz is becoming the standard for a variety of reasons, not the least of which is that you don't have to be concerned about channel control. Using 2.4 Ghz allows you to fly with any number of other folks without concern for interference. You can get basic 2.4 Ghz radios starting at $100 and go up dramatically from there, depending on how many channels and bells/whistles you want/need.
I won't discuss used because that can be all over the place. I will only comment on new radios.
First question: Are you flying alone, in the middle of nowhere or are you flying at a club?
Are you going to use standard sized servos or will you be using micro servos up in the nose to save weight?
For the lowest cost for transmitter, receiver with standard servos, there is a Futaba 3 channel AM radio. Works fine, but not my first choice. About $55
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**&P=ML For lowest cost with micro servos and receiver, HItec Neon FM 3 channel:
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**&P=7 If you are only going to have one plane and it will be R/E or RES or R/ E motor, these will get the job done.
Four Channel FM - available for $100 to $115, depending if you want standard or micro servos- Hitec Laser
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Spektrum DX5e 5 channel 2.4 GHz - $100 + servos
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If you are going for lowest cost for new equipment, those are my recommendations, but I would not suggest you buy one of them. They work fine and are good values. I always recommend going to 2.4 GHz to eliminate channel conflict, among other benefits.
I always assume you will have more than one plane and will move into more complex planes. I recommend computer radios and at least channels
Hitec Optic - $160 to $220 depending on the model
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2.4 GHz Spektrum DX6i - $200 plus servos
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Airtronics 8 channel 2.4 GHz with 2 receivers$229 - plus servos
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We can go on for pages about the merrits of 2.4 GHz, but it is enough to say that it is the current standard. 72 MHz is fading out. In this month's Model Aviation, the President of AMA talks about being unsure how long we will be able to hold onto 72 for hobby use.
Futaba early sets, some sets could be reprogrammed to be on logical channel '0' so they all interfered with each other. Just switching on long enough to read the battery voltage and then switching off would do it.
This was never formally admitted as a problem by Futaba,..
Futaba chipsets are only rated to about 55-65C. In hot sun in a closed fuselage some sets have packed up completely. This has been independently tested by a modeller and established beyond my reasonable doubt. Futaba don't admit to the problem.
Early spektrum receivers would, if a servo drew enough power to drop the avionics voltage below 3v, take up to 30 seconds to reboot, which is handy if you have just pulled up the undercarriage and lose control. Later sets will reboot in a couple of seconds. After JR held their hands up to that one... `With a 72Mhz set if ou lost control for half a second due to a low voltage, you would be fine immediately the voltage rose..just a short glitch maybe.
What else? Mmm. *Some* chipsets draw about 50-70mA. A typical HF set is
5-10mA. Doesn't sound like a lot, but its CONTINUOUS and has been a possible cause of BEC overheating in electric aircraft, and somewhat shorter pack duration in people using them with separate batteries.
XPS sets have been shown to simply not do what is claimed, and have been associated with several shootdowns..no one ever really go to the bottom of that one. Some people have had trouble free operation with them too.
Simpler cheap sets like Assan, which we have used, definitely slow down when used in a 'busy' 2.4Ghz environment. Their response to interference is to discard frames so only the odd one gets through. This is not fatal, but its a tad unnerving 'My plane just felt sluggish: I dont think I wanted to fly it' was the comment from my friend on that one...
2.4Ghz antenna are very short. This is wonderful if you have a small balsa or glass fuselage - no more dangly antennae hanging out the back like its the wrong time of the month for the model, In a CARBON fuselage is an utter disaster. Carbon is opaque to 2.4Ghz. So you need a receiver that has the capability - or you have to concoct - a way of mounting a remote dipole (or two if the set is twin RF like Spektrum). You cant just tape the antenna on the outside of the fuselage (that actually isn't a good idea even on 72Mhz).
So whilst shootdowns*, and glitches are gone forever, a whole new set of issues to do with voltage stability, heat, and the issues of antenna placement have occurred instead.
I want 2.4Ghz like mad. But its costly..no 3rd party receivers since every manufacturer uses a different modulation system. And there are still issues with ALL of the sets currently o the market.
If I were coming back into the hobby, as a solo or remote site flyer, i'd pickup a dirt cheap 72Mhz set, especially if it had an RF module.. because its cheap, its good enough, receivers are cheap, and 3rd party are avaialable. THEN you maybe can think about slotting a 2.4GHz module in the back later on.
But I wouldn't be in a hurry.
There are more sets coming out from different manufacturers, who have waited, and looked at the problems of the early sets, and solved them.
except the Futaba ZGUID issue, and some anecdotal XPS issues. Don't buy XPS..there are better sets at the money.
I agree very much with NP's post. Get a 72 MHz of a brand that you like the feel of. I use Futaba but have a JR that feels really good. Buy a flight pack with micro servos for the sail plane. The Berg 4 channel is a full range Rx and very light. I personally love Expo and dual rates but you may not need them. mk
So most of the problems relate to early models and/or to cheaper radios. While I can't argue with the suggestion of buying a 72 Mhz set if he isn't going to be flying with other folks, it still seems to me that it isn't the best way to go in the long run.
No. The futaba/heat issue is still unresolved. The issues of 2.4Ghz propagation are ubiquitous. As are the issues of rebooting and resynching after momentary power loss.
Im not syaing te stuff is crap -= far from it, but there are still resolvable issues - so wait till they are!
and learn to live with the unresolvables, as we had to live with metal to metal interference, rusty wire syndrome and other multipath, and peg on board systems.
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