bkdavy

My Feedback: (1)

I'm making my first venture into Giant Scale with a 30% Pilot RC Yak 54. The plane will have 5 HD-9150 Servos and one standard servo (probably HS-425). I'm expecting in the neighbor hood of 3-5 amps required to power everything.

Looking at the electronics, I want a highly reliable power source, which means two LiPo batteries. Since the voltage is over the normal 6 volts rated for my reciever, as well as the ignition voltage for the DLE-55, I'm planning on a 6 volt voltage regulator that will power everything. I'm going to build the setup myself, since it only requires a few inexpensive electronic parts. The plan is to run each battery through a MBR1045 Rectifier Diode (rated at 10 amps). The Diodes will ensure the batteries discharge equally. Then I'll use an LM7806 and and MJE2955 Power Transistor to provide a 6v 10amp regulated power for the reciever and the ignition.

Has anyone ever tried something similar? My concern is the high cost of the voltage regulators available commercially. Using this system I can provide redundant batteries and regulators for a small fraction of the cost. Is there something else I'm missing?

Brad

3dsky

My Feedback: (84)

The down side is testing. Isolating you ignition power from the receiver power is another problem. If this is your first time with a gasser it may be better to buy only what is needed for the 50CC size plane to give yourself a chance to see what is required. Minimum setup to me would be a Smart Fly Battery Share and 2 Fromeco 2600 mAh Relion batteries and one Smart Fly regulator. Top it off with a Smart Fly Optical Kill Switch with a 4 cell NiCAD for ignition. This as cheap as I would go. Total cost about $230

I have been using the Smart Fly products with great success. There are others that produce fine power systems for any size gassers. It comes down to confidence I my equipment and spending $250 on a power system to keep my $3000 (plus) plane from killing someone or destroying itself is cheap. Testing, I have a lot of confidence in the products I buy because of the number of installed systems and My first Smart fly was tested for a summer in a smaller low cost plane until I had some confidence in the application. Yes, I could build something cheaper but it would be hard to compete with the research that these guys put into their systems. I just want to fly and I think it is worth it. Yes, I am sure these guys had to start out just like you are and that is great because after several years of testing guys like me just pay & stuff the plane and go fly. Good luck and keep it safe.

latitude777

Im in the same boat as you mate, trying to figure out what setup etc for my first gasser.. DA engines australia told suggested i use the KISS Principal..

Forget voltage regulators etc etc and go with batteries that you can plug straight into the receiver. A123 cells of any description apparently when fully charged only put out just above 6volts. (6.4-6.6 max) but drop quickly to 6 volts operating where they stay for most of their cycle. Most servos on the market can handle this voltage no problem at all.

So just plug one straight into your batt channel on your rx and the second into any spare channel, this means you only have to run 2 smaller batteries 1800-2500mah A123's and the second is your spare (redundancy?!). Then just get a small nicad for your ignition.. theres nothing wrong with nicads and they're cheap and reliable.

Why waste time and money on voltage regulators and other techwiz stuff when this would/should work just fine?!

I've been told even guys running 35% planes are using this setup with no problems also.

Some food for though maybe?!

3dsky

My Feedback: (84)

Not using a regulator is ok if you are using servos and receiver that will take 6.2 to 6.8 volts. The newer stuff will take higher voltages but you should check the specs. KISS is OK but since this is your first gasser I would use a system that has been tested by a club member and you have seen the plane fly more than once.

I never had a regulator go bad and if the system is tested for total current and you use a regulator to handle the full load current of you system I would expect the regulator to last forever. All my 50CC and bigger planes have a power distribution board and a regulator with the (2 packs) LiION or A123 cells. Regulator is set to 5.8 to 6.0 volts. This has been the best for me and this is what I recommend. My A123 packs test out over 6.2 volts even after a flight and when I turn on the switch I see 6.8 volts, I just do not like the peak so I still use a regulator. I am testing an unregulated A123 on a 40-size plane and after a season running that way I will use it in the gassers.

I recommend picking up a Hanger 9 voltage/AMP meter and do your own testing and ask around the field.

JNorton

My Feedback: (2)

I'll comment on using a linear regulator. Yes it will work but at the cost of efficiency. All the voltage above 6 volts is dissipated as heat. Not a good engineering decision from my viewpoint. Your estimate of amperage drawn is too low in my opinion. It will peak much higher.

I would use A123 batteries. Bite the bullet buy a charger and enjoy. These batteries have excellent discharge characteristics. Red Schoefield the battery guru, has an article in this month in the AMA mag about A123 he has used for the last year. Definitely good reading. Use a heavy duty switch too.

John

apalsson

My Feedback: (1)

I would take Scott's advice, he is an experienced flier and a sensible guy.
I use the same setup on all my bigger planes and have never been let down.

jbarnes

Something you might want to think about that I do. I use only A123 packs but on 50cc and less I use one 2300 pack anything over 50cc I use two of those packs. I've been using the Ignition Battery Eliminator's from TBM for the last several months to avoid another battery for the ignition. For $50 you can avoid a ignition battery and have a electronic cutoff via a switch on your radio. This also allows you to avoid a second switch on the plane. I have these installed on three of my aircraft and have had no issues. Jerry.

ACMichael_G

Hey Bkdavy,
I am glad that I found this post but I am sad that I found it too late. I just lost a 35cc aeroworks plane using the HD-9150 servos on ailerons and elevators. I was performing a flat spin and when I came out all the HD-9150s quit. I only had throttle and rudder (on Hitecs) left but I have yet to figure out how to perform a knife edge landing.

I was using a 2S lipo and CC bec 10amp regulator because Futaba Tech Support told me that using the A123 voids the warranty. So maybe by not voiding the warranty I 'voided' the whole plane.

Does anyone know anything about the quality of the hobbycity HD-9150s? If I put another plane together I want to be certain that those servos won't fail me again. I'm not that rich!


Michael

jbarnes

Mike, You need to think of quality over price. In the long run you will lose more by using cheap servo's than you will ever save. You can buy Hitec 5645's for $40 on RCU and they will not fail you. They are a strong metal gear servos. You can run Hitec's on A123's with no issues, been doing it for years. Most all us gas guys are running 123's now because you avoid the possiblity of fire and you need no regulators. Don't spend your money on a quality plane such as an Aeroworks and then take the risk of servo failures by buying cheap HD servo's. Jerry.

FlyM

Michael,

You stated that "all" of the HD-9150 servos quit working. I am guessing there were 4. Did you you ever find out exactly what happened? I am planning on using some of these myself and now I wonder if I should or not??

Loyd

Texastbird

I don't think the 9150 could have gone bad at the same time. It must be something to do with the regulator. I don't see any point in running a regulator with Lifes or A123s. Its very possible the 4(?) 9150s were trying to pull more than the 10 amps coming out of a spin with some extreme stick movements.