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I have been flying a Sundancer 330 using a 2808/12 Tower Pro motor (1800 rpm/v), 7×5 APC-E prop, ZTron F/F timer, a micro servo for D/T, and Enerland 700 XG and 800 XP 3cell batteries. 10 sec runs result in 2 minute maxes generally.
I notice that it is best to burn off the first run to get the dip in voltage out of the way. Then, I start putting up flights. I usually fly 3 flights on the battery and then change to a fresh one. This works OK.
My question is, what do you all do-fresh bat each flight? Advice from the contest flyers would be appreciated. I have never tried running the cells down because I want to baby them.
Do any of you know of other brands of cells that will perform as good as Enerlands (Polyquest)?
desertflyer, Yes, I usually have a fully charged battery for each contest flight. Not so for test flights, but even there I never run off more than about 25-30% of a battery’s capacity. I have two batteries for each plane…also have two chargers, plus a field booster battery to supply one of the chargers, so it’s not hard to have fully charged batteries ready. The chargers can also discharge. After the flying session is over, I discharge all batteries to 3.85 volts per cell for storage.
You are correct to briefly run the battery before flying. This warms the battery. A warm lipo has lower internal resistance and can delivery more voltage to the motor. However, there is a point of diminishing returns. Pre-run too long and the battery will begin to deplete. Also, the benefit is partially offset by heating of the motor coils, which raises their resistance and reduces power. The best of all worlds is to have a heater box for the batteries, to keep them warm before flying. I haven’t got to this point yet.
It seems that new and better lipos are coming out all the time. It’s best not to stockpile one brand, because they will soon be out-gunned. Right now I’m using Fusion-Pack 3S and 4S 800 mah 25C packs. They have lower internal resistance per cell than my Enerland 700 4S. They are also cheaper.
Dick
In my post above I mis stated my motor. It is a Tower Pro A2208/12, not a 2808 as stated. oops!
Hi desertflyer, I looked up the TP A2208/12 motor … yikes, the price is only $9.80 … and the weight only 36 grams. It is cool what the Chinese can do with low cost manufacturing. The size of the motor seems well suited for your airplane.
I think you could get by with a smaller battery, say 600 mah, and save a bunch of weight. Just a suggestion, but check out this battery: https://fusion-pack.com/productdetail.aspx?id=166&cat=86
Dick
I don’t feel bad that I bought my motor for 15.95 from BP Products. I thought I was getting a deal! Electric Free Flight in Fresno sell this same motor for 16.95. This motor turns a 7×5 APC E Prop at 13K but I don’t remember the wattage. Now BP Products has an Ultra version that is good for 200 watts. I have one but haven’t tried it yet.
Desertflyer, Last year I flew with the Axi 2208/16 a CAM 7 X 5 folder and a 700 mah PQ 3 cell. On 10 sec. motor runs I could get 3 motor runs that would provide a max before going to a new battery. Like Dick, I use 2 chargers on the field. If we go to 5 sec. motor runs I will charge every flight. I agree with Dicks comment about battery technology but I am still brand loyal to known quality product. I am one of those quality is cheaper guys.
I have begun a pre-flight routine that helps ensure the battery is good. These controllers will shut down the motor at one second if the battery has a problem. Now, when I load a battery, I’ll do s ashort (more than one second ) burst. Launching a start a start-on-release plane system that shuts down at one second results in bad things. That’s why I need a new fuselage for the Marval!
Every contest flight that I’ve cared about has been with a fresh-charged battery. My mentor Jim explained it—volts=rpm.
What is the all-up weight of the Sundancer 330 with your rig?
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