skysfallin

My Feedback: (10)

I'm putting together an Aerworks YAK 50cc and want to make sure I get this right the first time. Running all Hi Tec MG 5985 servos. Airtronics RDS 8000 and reciever. Smart Fly Fiber Optic cut off switch and a Smart Fly Power Expander Sport. I am a little unclear on the set up. Does the power expander supply a seperate power feed to the RX and another to the servos to eliminate surges to the RX. Is there a benefit to running two RX's ? If so what and how would that set up work. AS far as the engine goes is there any shielding that has to be done other than making sure the plug wire is protected from chaffing. Running Super Switches and all heavy duty silicone servo extensions. Am I missing anything? This is my first gas plane so I'm trying to aviod any heart aches from th wrong setup. I'm open to any advice and appreciate all. Thanks in advance.

BuschBarber

My Feedback: (2)

Redundant Rx's help prevent losing the aircraft if one of the Rx's should fail. Generally, you would split the load between the two Rx's, especially putting one Aileron half, Elevator half, etc., on each Rx so if you loose half of a Control Surface, you still have the other to land.

Power Expanders ensure separate Voltage Regulation to all channels and allows you to set up Redundant Batteries and Switch Harnesses so if one breaks down, you still have the other. It allows you to use separate Batteries to the Rx and the Servos.

I fly 50cc gas planes and I have not used a Power Expander, but I have used Redundant Rx batteries by connecting the second Switch Harness to a Servo Channel port using a Y harness. Perhaps, for a 100cc or above, I would, but it doesn't hurt if you want to add that to your 50cc bird. It comes down to how much do you have invested in your aircraft and what risks are you willing to take.

If you are using a 2.4Ghz radio, you are less likely to suffer from RF noise and with the short Antennas, less likely to break an antenna or cut it short. You can Bind each Rx to the same Tx and Model Memory.

I use a Smart Fly Fiber Optic Kill Switch, as well. Much more reliable than a Choke Kill. If you have ever had to land a Hot Bird or Ditch on Takeoff because your Throttle failed, you will appreciate a Tx operated Kill Switch.

skysfallin

My Feedback: (10)

Forgot to add, the ignition battery is 2000mah and the RX battery is 3600mah. Is it better to run two 2000mah and can you run them parallel or run them seperately?

BuschBarber

My Feedback: (2)

When you run two batteries and switch harnesses off the same Rx, they are running in Parallel, which means that the Voltage stays the same but the Capacity doubles. Fromeco and Duralite, to name a couple, sell 4cell Lith Ion packs as 2S2P, for the Rx. This offers some Redundancy and saves weight. I do not remember seeing someone use Redundant batteries for Ignition.

flatspinjim

My Feedback: (3)

Setting up a 50cc plane really isn't that much different than setting up a 1.20 size glow plane. You're not adding a bunch of servos so there really is no need for a power expander. The servos you are using will use more amperage though so make sure you use a good battery. My personal setup would be one 2300mah A123 battery going into a Smart-Fly Super switch. A deans connector going from the battery to the switch and 2 JR type leads coming out of the switch going into the reciever. If you wanted redundency you could run 2 1100 mah A123's through their own switch.
On my 100cc planes I run the same setup only I use 2 2300 mah A123's.
A single 4.8 volt 1200 mah nicad will be plenty for the ignition. Most ignitions will fail eventually with more than 6 volts.

skysfallin

My Feedback: (10)

Thanks for the replies, all good stuff. I just found one of my brand new so called super switches bad. Only turning on when you wiggle the switch. You try to buy good equipment and you always have to double check everything. I totally understand redundent systems.

JOHNS3D

My Feedback: (5)

i dont know if you have already order the stuff, but a power expander for a 50cc is useless, you dont need it, maybe for a 150cc and more, but including a 100cc is just fine a dual battery pack with a wolverine switch from fromeco for example.

If you want good battery pack and just need to be sure, get a A123 or li-ion from Fromeco, or hangtimes.com aslo have amazing packs. You can visit http://www.rcuniverse.com/forum/forumid_110/tt.htmyou will find much more info there.

StevL

You just made me think... Why land a hot bird? I have flown a couple planes (both glow) that either the thottle linkage, servo, etc. failed. As long as everything else is working I just flew the plane until it ran out of fuel, kept it at the down wind side of the runway so I would be ready to land into the wind, not a big deal.

Now ditching on take off, would you please explain? I vision a dead stick on take off, why would I need to kill it?

To be honest I've never figured out why we put alternate ways to shut down a gas engine but not a glow?

Steve

BuschBarber

My Feedback: (2)

I mentioned takeoff because until you get some altitude, you do not want the engine to sag. I would rather Kill the engine and land. I have had situations where the Throttle servo stuck or quit at a low Throttle setting where the plane was going too fast to land but too slow to gain altitude and just looking to stall.

As far as Glow engines, that is what Throttle Cut is for, but if the servo fails, that will not help you. Only a device to shut off the fuel line would help or some kind of Choke.

StevL

Got it...thanks!

Steve

ARF WRECKER

I dont agree with the not needed power xpander on 50cc craft. some have many functions i.e. flaps retracts smoke etc. gives you the ability to if you dont have digital programable servos the ability not to have to reverse one, also some have built in regs and dual power inputswith a fail on input switch(powerxpander sport plus with optical kill for gas) I find this a very good solution for non y harnessing controls and redundancy do not weigh much and offer many plus. I agree is not a must have item but can simplyfy programming on a lot of levels a good constant source of power and manny optional ports for your gear.

skysfallin

My Feedback: (10)

The main reason I went for the power expander is just to make sure there is clean power to the RX and the servos at all times. As mentioned before its probably overkill but it this is my most costly plane to date, so if I can reduce some mechanical issues the expiration date may be extended. Hopefully.........However I really appreceiate everyones input.