RC Groups

RC Groups
    High Performance
        F5B on the cheap

#1 Bernie Wolfard Sep 22, 2003 01:35 PM

F5F on the cheap
 
I know the title is an oxymoron. However . . .

I have inherited a broken but fixable Surprise 10. My problem is I cannot afford a full blown 10 cell power system. This seems likes the biggest bang for the buck for around $270 minus batteries witch I can get cheap.

1. Mega 22-30-2
2. 5.5 to 1 reduction which I already have
3. CC 80 amp controller which CC says will work on a 100 amp system for brief periods like F5B.
4. 16 X 15 prop

This system will pull around 100 amps static according to MotoCalk. I am looking for blessing for this system or suggestions for a comparatively priced system that might be better. I already know I should spend more but my goal is to be able to fly and learn not win. Any more $$ and I donít fly.

Bernie

#2 soholingo Sep 22, 2003 02:15 PM

Look for a used competition system. I had that exact same setup, and for the mega to produce the numbers you are looking to get you will need a lot of cells. Your controller will only handle up to 20 cells. I just sold my mega setup. Youi will also need to turn a bigger prop. I ran the numbers and 100 amps looks extremely optimistic.

Some of the best cheap setups are used aveox f10 f12 f27 with the responding controller...

#3 davidleitch Sep 22, 2003 02:52 PM

Bernie

One of the guys I sold an FVK Absolute to here in Australia put a very similar system in and reported being very happy with it. Provided the gearbox is reliable at that power I think your only issues will be a bit higher weight than desirable and a bit less efficiency.

#4 soholingo Sep 22, 2003 02:55 PM

David,

How many cells and which prop with the mega 22/30/2 setup? The kv is 1700 or so, and with 5.5 reduction the prop is spinning slowly....

Man, I just sold that setup, if it's a winner, I am going to be miffed...

Jay

#5 Bernie Wolfard Sep 22, 2003 03:00 PM

Two answers two diametrically opposed responses. Gotta love electricís.

David, you hit quickly on my weak link. I do not know what watt rating my gearbox is good for or if can handle the load. But then, whatís the worst that can happen (famous last words). The Surprise 10 has a big wing and can handle the weight. As to efficiency, that is one of the things you give up with low cost. But if it flies good enough to finish a F5F task I will be happy.

Soholingo, what did you run your numbers with. I now Motocalk is only for a baseline but I can easily go with a steeper pitched prop if I donít pull enough amps originally.

#6 Bernie Wolfard Sep 22, 2003 03:03 PM

Soholingo, I could special order a 22/30/1, Kvm estimated at 3600 :rolleyes:

#7 Bernie Wolfard Sep 22, 2003 03:30 PM

Just looked up the Kv of a Hacker B40 F5F, it is 5k. Perhaps you are correct Soholingo. I will see if I can get a 22/30/1.

Bernie

#8 soholingo Sep 22, 2003 03:37 PM

Flutterbug,

I did a ton of research on this. And I thought the mega would be a good motor for my f5b and 16 cells, but at 5:1 the rpms are too low, UNLESS I used a 20 inch prop...

http://www.rcgroups.com/forums/showt...highlight=mega

http://www.rcgroups.com/forums/showt...highlight=mega


check out these threads....

also the setup is .5 ozs heavier than a comparable b50 setup that I ended up keeping...

Jay

#9 Bernie Wolfard Sep 22, 2003 03:51 PM

Thx Jay. I think I will look for a 1 turn motor, but they might be made from pure unobtainium.

Bernie

#10 WimH Sep 22, 2003 05:10 PM

Re: F5F on the cheap
 
Quote:

Originally posted by Flutterbug
I
2. 5.5 to 1 reduction which I already have
3. CC 80 amp controller which CC says will work on a 100 amp system for brief periods like F5B.

I'd try getting a Mega 22/20/1 ( KV around 6000). This will be quite ok with your 5.5:1 geardrive ( if it's strong enough...)

Start with an Aeronaut 14*10 prop and work your way up. If not flying competition, try7/8/9 cells. Bear in mind there's not all that much difference in performance between an 80A and a 120A setup. But the 120A or more will demand the best cells. If I were you, and not flying competition, I'd use 7 GP3300 or GP3000 cells, shoot for about 80-100A (adjust with prop, again; there's not that much difference between 14 and 18 inch props ( in F5F the best are using 17*18 by the way), it's much more important to have one that suits the plane and your flying style.

Wim ( who just totalled his prebroken/fixed Surprise 7 in this weekends comp on lap 22)

#11 davidleitch Sep 22, 2003 05:21 PM

Wim that is bad news on the Surprise. How did you manage that?

#12 davidleitch Sep 22, 2003 05:39 PM

Hi Bernie

I haven't used the geared Mega setup, so my opinion ain't worth much.

I reread Shawn's setup in his absolute and he finally settled on:
Quote:

calc programs, adding the $$, readding the dollars and talking to various people in person on the phone and through ezone. With all that done I've taken the plunge and have just ordered from Nippon Dave the motor, speedy, prop and spinner. Setup is going to be

Mega 22/20/2
Aveox 3.7:1 gear box (P37)
14.5x10 Falco carbon prop
Jeti Advance 70 opto
10 CP1700 cells

Figures from both p-calc and e-calc suggest about 60amps draw with 100ounces of static thrust
He reported being very happy with that setup. I can also say that if you have a brushless controller then the Elios 37 with included 3.7 gearbox from www.flyelectric.com at about $US210 will give good brushless performance on a 14x10 prop. I have used that setup. Its not as good as my current setup, but its certainly good for up to 70 amps and probably 80-90 briefly.

Goodluck with your choice

#13 soholingo Sep 22, 2003 06:16 PM

that setup is MUCH different from what flutter bug was proposing... gotta read the small print...

#14 soholingo Sep 22, 2003 07:08 PM

Re: Re: F5F on the cheap
 
Quote:

Originally posted by WimH

Start with an Aeronaut 14*10 prop and work your way up. If not flying competition, try7/8/9 cells. Bear in mind there's not all that much difference in performance between an 80A and a 120A setup. But the 120A or more will demand the best cells. If I were you, and not flying competition, I'd use 7 GP3300 or GP3000 cells, shoot for about 80-100A (adjust with prop, again; there's not that much difference between 14 and 18 inch props ( in F5F the best are using 17*18 by the way), it's much more important to have one that suits the plane and your flying style.

Wim ( who just totalled his prebroken/fixed Surprise 7 in this weekends comp on lap 22)

you say some interesting things here Wim,

1. Not that much difference in 80a and 120a? Is that really true?

2. And when you say there is no differnce in props, you have to explain that better... there is a differnce in going from a 13x7 to a 14x9.5 so going to 18" should be even better.

3. Lastly what happened whith your pre damaged s7? What was the damage? How did you repair it? etc...

Thanks,

jay

#15 Bernie Wolfard Sep 23, 2003 01:24 PM

David, you gave me an idea that got me outside the box. I just email Model Motors in France to get shipping info on their F5F set up. The price is really attractive and it is something different.

Anyone ever used on of these motors and controllers. I saw a thread here with a yes it is not its not argument about the controller being a Jeti but nothing very useful about actual use.

I plan to fly in competition, I just don't plan on winning, at least for awhile. I am closer to the bottom of the learning curve in this area of electric flight, but our local club PASS has a strong F5B/F5F contingent.


All times are GMT -5. The time now is 12:08 PM.