no receiver battery???
08-31-2003, 02:50 PM
#1
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no receiver battery???
I have been into powered flight for a couple years. But.......I have been wanting the GP Spectra ARF sailplane.
I am lost on electric........ but am learning. I still don't understand the power source for the receiver in the Spectra ARF or RTF.
I think there is some kind of device that "taps" regulated power from the motor battery.
MY QUESTIONS: Is this device part of the speed control or???? Nothing is explained about this that I could see. What if the motor battery goes dead???
Can I use 4.8V pack .... or will that create too much weight for this plane.
PS........ ALSO.... I have a 7 channel receiver and standard servos. Can this be used in this sailplane???
Thanks in advance........ lownslo...
I am lost on electric........ but am learning. I still don't understand the power source for the receiver in the Spectra ARF or RTF.
I think there is some kind of device that "taps" regulated power from the motor battery.
MY QUESTIONS: Is this device part of the speed control or???? Nothing is explained about this that I could see. What if the motor battery goes dead???
Can I use 4.8V pack .... or will that create too much weight for this plane.
PS........ ALSO.... I have a 7 channel receiver and standard servos. Can this be used in this sailplane???
Thanks in advance........ lownslo...
08-31-2003, 03:16 PM
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no receiver battery???
I was about to post a similar question when I found the explanation on Tower Hobby's website. I too am looking at the Spectra, because I already own the Spirit, which is the non-electric version of the same glider. The Spectra appeals to me because it would give me some redundant parts between the two gliders. Plus I learned the other day that there's another company that makes alternative wings for the Spirit/Spectra.
What I learned about the power requirements, is that there are speed controls that also power the receiver. They listed one unit called the ElectriFly C-30:
http://www2.towerhobbies.com/cgi-bin...?&I=LXUR96&P=M
It provides a power tap for the receiver, and then the motor battery drops to 4.8 volts, it automatically shuts down the motor so that you can still control the glider for landing.
I'm probably going to order my Spectra this week. I fly at an airfield where there are days when there are just too many powered planes aloft, and I'm afraid of clothes-lining someone with my high-start. I'm not getting the stick time on my glider because of this. I started to build a power-pod for my Spirit that would use a Norvel .061 glo engine, but decided that I would rather have an electric for the ease of use.
Good luck!
What I learned about the power requirements, is that there are speed controls that also power the receiver. They listed one unit called the ElectriFly C-30:
http://www2.towerhobbies.com/cgi-bin...?&I=LXUR96&P=M
It provides a power tap for the receiver, and then the motor battery drops to 4.8 volts, it automatically shuts down the motor so that you can still control the glider for landing.
I'm probably going to order my Spectra this week. I fly at an airfield where there are days when there are just too many powered planes aloft, and I'm afraid of clothes-lining someone with my high-start. I'm not getting the stick time on my glider because of this. I started to build a power-pod for my Spirit that would use a Norvel .061 glo engine, but decided that I would rather have an electric for the ease of use.
Good luck!
09-02-2003, 10:45 AM
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no receiver battery???
The thingy you're looking for is called BEC (for Battery Elimination Circuit). There has been a lot of argument about BEC, some people love it and some people hate it.
The BEC circuit (built into the speed controller) taps into the flight battery and draws off 4.8v which it feeds to the receiver. As soon as the battery pack gets low on volts, the power to the motor is cut off while power to the receiver is maintained. The load of the receiver and two servos is nothing compared to driving an electric motor up front, so as soon as the motor is shut off the voltage recovers and gives you plenty in reserve for the receiver.
Points for BEC:
- You don't have to carry a separate receiver battery on your plane.
- You know your receiver battery is freshly charged with each flight.
- As long as the motor is running, you know the receiver battery isn't about to go flat.
- Looking after one battery is a lot easier than looking after two separate systems in the same plane.
Points against BEC:
- If something goes wrong with the flight battery, the receiver stops as well and your plane crashes. With a separate receiver battery, you could still land your plane if the motor pack failed.
- In a glider, people generally want to stay up as long as possible. If you climb until the motor cuts out, your batteries are already low and if you stay up too long, you can still flatten the battery and crash.
- Drawing your receiver power from the same supply as the motor is a good way to pick up interference.
- A fresh 7-cell pack generates about 9v, and your receiver only needs 4.8v. The rest of the power is thrown away as heat, and a bad setup can cause overheating and shutdown of the whole speed controller (including the reciever power tap, so the plane crashes).
That last point is not usually a problem with the sort of plane you are looking at. When people start using 10+ cells there is a lot more heat to be dissipated, which can cause problems. Also, more servos will put more strain on the BEC circuit. If you are talking about 7 cells and 2 servos you shouldn't have any problems at all, many people fly this way already. If you have 10 cells and 6 mini servos, BEC is a very bad idea because the poor circuit is going to be working a lot harder than the manufacturer ever intended. Note that mini servos usually draw a lot more current than standard servos, for that brief instant when they start moving. So if you have 4 mini servos in your plane and you move them all at the same time, the load will almost certainly exceed what the BEC was designed for. A separate receiver battery pack only weighs one ounce.
For low power applications (7-8 cells and 2 servos), BEC is pretty safe and you shouldn't have any problems at all. Most small electric flyers use BEC every day for their Sp400 planes. Stay within the limitations of the equipment and it should work fine.
The BEC circuit (built into the speed controller) taps into the flight battery and draws off 4.8v which it feeds to the receiver. As soon as the battery pack gets low on volts, the power to the motor is cut off while power to the receiver is maintained. The load of the receiver and two servos is nothing compared to driving an electric motor up front, so as soon as the motor is shut off the voltage recovers and gives you plenty in reserve for the receiver.
Points for BEC:
- You don't have to carry a separate receiver battery on your plane.
- You know your receiver battery is freshly charged with each flight.
- As long as the motor is running, you know the receiver battery isn't about to go flat.
- Looking after one battery is a lot easier than looking after two separate systems in the same plane.
Points against BEC:
- If something goes wrong with the flight battery, the receiver stops as well and your plane crashes. With a separate receiver battery, you could still land your plane if the motor pack failed.
- In a glider, people generally want to stay up as long as possible. If you climb until the motor cuts out, your batteries are already low and if you stay up too long, you can still flatten the battery and crash.
- Drawing your receiver power from the same supply as the motor is a good way to pick up interference.
- A fresh 7-cell pack generates about 9v, and your receiver only needs 4.8v. The rest of the power is thrown away as heat, and a bad setup can cause overheating and shutdown of the whole speed controller (including the reciever power tap, so the plane crashes).
That last point is not usually a problem with the sort of plane you are looking at. When people start using 10+ cells there is a lot more heat to be dissipated, which can cause problems. Also, more servos will put more strain on the BEC circuit. If you are talking about 7 cells and 2 servos you shouldn't have any problems at all, many people fly this way already. If you have 10 cells and 6 mini servos, BEC is a very bad idea because the poor circuit is going to be working a lot harder than the manufacturer ever intended. Note that mini servos usually draw a lot more current than standard servos, for that brief instant when they start moving. So if you have 4 mini servos in your plane and you move them all at the same time, the load will almost certainly exceed what the BEC was designed for. A separate receiver battery pack only weighs one ounce.
For low power applications (7-8 cells and 2 servos), BEC is pretty safe and you shouldn't have any problems at all. Most small electric flyers use BEC every day for their Sp400 planes. Stay within the limitations of the equipment and it should work fine.
09-02-2003, 11:14 AM
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no receiver battery???
Thanks guys, Steve.... your reply was well written and "understandable". I thank you both!!
I think I am going to order mine today from the LHS. (she matches "the big boy's prices).
I think the final choice is the Hanger 9 Aspire..RTF (HAN1950). The only problem is that it has a 6 cell 1500 Mh battery instead of the preferred 7. I would build one, but I am a slow builder. I got the "bug" to fly now!!
(to my knowledge, this plane does not come in an ARF version where I can select the parts). I have 4 powered craft so this plane is to try and get my wife into the hobby, and do some "relaxed flying" 
Right now I am not looking for top notch power, just average, to try out this apsect of R/C flying. MAN...... I got the "sickness"!!! ....lownslo....
Bob
I think I am going to order mine today from the LHS. (she matches "the big boy's prices).
I think the final choice is the Hanger 9 Aspire..RTF (HAN1950). The only problem is that it has a 6 cell 1500 Mh battery instead of the preferred 7. I would build one, but I am a slow builder. I got the "bug" to fly now!!
(to my knowledge, this plane does not come in an ARF version where I can select the parts). I have 4 powered craft so this plane is to try and get my wife into the hobby, and do some "relaxed flying" Right now I am not looking for top notch power, just average, to try out this apsect of R/C flying. MAN...... I got the "sickness"!!! ....lownslo....Bob
09-02-2003, 11:41 AM
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no receiver battery???
Originally posted by lownslo
The only problem is that it has a 6 cell 1500 Mh battery instead of the preferred 7
The only problem is that it has a 6 cell 1500 Mh battery instead of the preferred 7
09-02-2003, 05:54 PM
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no receiver battery???
This is a bit off the original question, but I wanted to throw in my 2 cents worth on the Spectra and the Aspire.
I own both. They were each very marginal performers with the stock motors in the direct drive configuration. The Spectra, which has well over 1,000 flights has a Magnetic Mayhem motor with a Master Airscrew gearbox (3.0). It swings the Master Airscrew folding prop; the 12 x 8. A 7 cell 1800 nicad gives me 5/6 climbs to a comfortable altitude.
The Aspire has the same setup, but the motor is the one that comes with the Master Airscrew conbo. Perhaps 200 flights on the Aspire.
I find the Spectra a little more stable in the air. It "groves" with very little input. If it crashes, I will buy another!!
2120 - I support the idea of redundent components. If you break a wing; just put the Spirit wing on. Could you tell that source you mentioned on alternate wings? Would appreciate it.
I own both. They were each very marginal performers with the stock motors in the direct drive configuration. The Spectra, which has well over 1,000 flights has a Magnetic Mayhem motor with a Master Airscrew gearbox (3.0). It swings the Master Airscrew folding prop; the 12 x 8. A 7 cell 1800 nicad gives me 5/6 climbs to a comfortable altitude.
The Aspire has the same setup, but the motor is the one that comes with the Master Airscrew conbo. Perhaps 200 flights on the Aspire.
I find the Spectra a little more stable in the air. It "groves" with very little input. If it crashes, I will buy another!!
2120 - I support the idea of redundent components. If you break a wing; just put the Spirit wing on. Could you tell that source you mentioned on alternate wings? Would appreciate it.
