WattFlyer RC Electric Flight Forums - Discuss radio control eflight

WattFlyer RC Electric Flight Forums - Discuss radio control eflight (https://www.wattflyer.com/forums/index.php)
-   Power Systems (https://www.wattflyer.com/forums/forumdisplay.php?f=17)
-   -   Newbie; power system for H9 Funtana X 50? (https://www.wattflyer.com/forums/showthread.php?t=39746)

HugoW 10-05-2008 07:31 PM

Newbie; power system for H9 Funtana X 50?
 
Hi,

I'm new here, this is my first post, although I've been reading quite a bit the last weeks. I posted this q on RCGroups, but then I thought, why not join the dedicated forum! So here we go (if the question seems familiar, you've probably read it on RCG. I copied/pasted...)

Here's the deal:
Plane (Hangar9 Funtana X 50) weighs 1600 grams without powerplant (so no engine/prop/spinner, no tank, no throttle servo, no linkage). To fit the .91, fuel it up, etc, takes about 1100 grams. So flying would be at 2700 grams. Hangar9 says 1.8 - 2.5 kg, but that's with a smaller engine and no fuel.

Electric, I was told 350Watts per kilogram would make a decent 3d performance. Estimating a flyweight the same as the .91, I need 945 Watts. Because the plane isn't built for electric, I think about using 2 3S packs in series, so I can place the batteries more easily than one 5S or 6S pack. 6S is 22.2Volt (right?), so I need the motor to pull 43 amps. Using a 3300mAh pack, that means a WOT time of 4.5 minutes. Now let's look for the bits, and their weight.

- I found this motor, TGY AerodriveXp SK Series 42-50 650Kv / 1150w. With 6S and 52 amps as in the second review, that would be 1154 Watts. It weighs 250 grams.
- Then I found this ESC, TURNIGY Plush 80A w/ UBEC Speed Controller. Should be able to handle the motor, weighs 120 grams.
- Let's say prop, spinner, mounting stuff, etc is about another 250 grams.
- Last but not least, 2 batteries; ZIPPY-H 3300mAh 3S1P 20-30C Lipoly Pack, each weighing 300 grams.
So, adding things up, the powerplant would weigh 1220 grams. With the plane, it would be a take-off weight of 2820 grams, with 1154 Watts, 409 Watt/kg.

Now for the 64k dollar question:
Did I understand it all correctly? Is the above correct and can I go electric (mild) 3D with this?

Oh, btw, I read Hacker makes nice motors and stuff, but I really don't have that much cash...

Thanks,

Hugo

EDFrules 10-05-2008 10:42 PM

Here's an my old X50 thread for reference:
http://www.wattflyer.com/forums/show...ght=Funtana+50 Use Himax 5030-390 motor specs as a reference for your system, should be in the ballpark.
Regards,
Jason

HugoW 10-06-2008 05:59 AM

Wow, that's one big motor. Mine is 250 grams, yours 390! But your set-up puts out 1250 Watts, mine 1150, so I shouldn't be too far off and saving a few grams. BTW, I see you use only 2100mAh packs, what flight time do you get with that?

Thanks for the input so far!

Cheers,

Hugo

EDFrules 10-06-2008 07:05 AM

If your motor will swing a 16 x 8-10 or 17 x 8-10 APC e-prop that should do the trick. Mine would hover @ about 1/2 throttle with plenty of pullout power. KV on your motor seems a little high for swinging a good sized 3D prop(?) Might want to check on a lower KV motor and see what prop sizes it will swing.

Jason

HugoW 10-06-2008 02:44 PM

Uh, side-step: 390kV * 22.2V = 8.658 rpm, right?

Take this motor:
http://www.himodel.com/electric/660K...ype_A4120.html
And reduce the RPM by gearing (almost) 2:1. Straigth gears shouldn't cost too much power, should they?

Or am I showing signs of beginners-stupidity now?

[EDIT]And what ever happened to '200W/kg' is enough to fly 3D'? I'd say with a 3 kg plane, 750 Watts would be plenty. But I read set-ups of over 1.5kW, here![/EDIT]

Thanks,

Hugo

EDFrules 10-06-2008 07:55 PM

I'm not a big fan of external gearboxes. That much more that can go wrong and crash your plane. If you don't get the lashing just right it will chew some teeth, usually when your plane is in a bad spot and...well you know the rest. Your motor on 6s would be swinging a small prop, not good for 3D work without the gearbox. I might reccommend rethinking the powerplant for this bird. This one looks like more in line with 6s packs:
http://www.himodel.com/electric/380K...ype_A4130.html

HugoW 10-06-2008 08:01 PM

Hey, good timing... I was just looking at this one:

http://www.himodel.com/electric/320K...ype_R4130.html

Swinging a 16x10 at 6S. I'll make a little set-up with the motor you recommend.

EDFrules 10-06-2008 09:01 PM

Yup, either one would probably work well. The slightly higher KV motor will have a little more RPM's to help get out of those bad spots. 5s on this plane is nice but with an outrunner I think you'd get anemic power. However I've seen other flyers use a Hacker inrunner on 5s with great results. Probably the best and lightest setup on this airframe but pricey. For value flying go with 6s/outrunner setup and you'll have plenty of power to spare. For me-hovering @ 3/4 +throttle is not an option. 1/2 throttle is where I like to see my planes hover. Less stress on the power system too. My .02

Regards,
Jason

HugoW 10-06-2008 09:04 PM

I'm ordering the motor, 16x10prop and 70amp ESC now. I don't do BEC, leave the little NiMH pack in place. I will go 6S, probably order some Zippy packs, they are popular here in the Netherlands. What flight times did you get with your small packs?

EDFrules 10-06-2008 10:09 PM

If you can switch to 900mah+7.4v lipos for lighter weight. NImh packs are getting a little heavy for this size airframe. I prefer BEC for smaller planes, a lot lighter weight. I was getting about 9-10min of hard 3D work out of 4200mah packs(6s2p-4 x 2100mah 3s packs). Still a little heavy. 3700 sized would probably be optimum weight with about 6-7min of 3D. The weight piles up pretty quickly on airframes:(

HugoW 10-07-2008 05:10 AM

I have a 2000mAh NiMH pack to use, at 114 grams. I'll look into the LiPo version, later, how do you tune the voltage back to 6V?

For power I'm looking at 6S 3300mAh packs, 569g, at US$ 93 each. I'll make a mock-up of the battery first, to determine placement and CG before I buy. http://www.hobbycity.com/hobbycity/s...idProduct=6419

I'm also thinking about cooling. The motor and ESC will get wind from the prop, but I'm considering to close of the air exits of the cowl, and dril some holes in the firewall. Then the air goes through the fuse, exiting at the servo holes at the back. I fitted small hipower servo's, the servo hole is still partially open with the servo fitted.

ministeve2003 10-07-2008 05:48 AM

d

EDFrules 10-07-2008 07:45 AM

Castle Creations makes a switching regulator that weighs 11 grams. http://www.castlecreations.com/products/cc_bec.html
Can be hooked to main pack or seperate power source. I've used a Medusa voltage reg as well in the Funtana hooked to main packs with no problems. For a plane this size a seperate RX power source is kind of overkill. Just extra weight for the power system to struggle with. By adding the switching reg to the main pack you save quite a bit of unwanted weight.
See the Funtana thread pics for some cooling tips. I drilled some holes in the firewall and cut out some covering at the rear of the fuse. That's on of the problems with the Funtana-no real cooling for packs and no battery hatch:(. Hope that helps.

Jason


Originally Posted by HugoW (Post 486432)
I have a 2000mAh NiMH pack to use, at 114 grams. I'll look into the LiPo version, later, how do you tune the voltage back to 6V?

For power I'm looking at 6S 3300mAh packs, 569g, at US$ 93 each. I'll make a mock-up of the battery first, to determine placement and CG before I buy. http://www.hobbycity.com/hobbycity/s...idProduct=6419

I'm also thinking about cooling. The motor and ESC will get wind from the prop, but I'm considering to close of the air exits of the cowl, and dril some holes in the firewall. Then the air goes through the fuse, exiting at the servo holes at the back. I fitted small hipower servo's, the servo hole is still partially open with the servo fitted.


HugoW 10-07-2008 09:12 AM

Ah, thanks for the cooling pics. Seems a little surgery is in order... The BEC is a good idea, saves another 100 grams, and setting it to 6V will boost the servo's a bit, too. I'm also looking into Amp monitioring devices, seem a neat thing to have.

HugoW 10-07-2008 12:15 PM

How about these packs:
http://www.hobbycity.com/hobbycity/s...idProduct=7638
Not very light, but 4000mAh and only 75 buck each.

EDFrules 10-07-2008 01:46 PM

If they are true 20c packs should do OK. Just monitor the heat after flights to see if you're not taxing them. I'm liking Fusion-Pack.com's 25c packs. They are good price and hold up really well.

HugoW 10-07-2008 02:02 PM

I'm finding these:
https://fusion-pack.com/productdetai...id=158&cat=116

But they are over a 100 bucks more and 700mAh less. Undoubtebly better quality, but I doubt the difference is worth it.

Or am I looking in the wrong direction?

Cheers,

Hugo

EDFrules 10-07-2008 08:48 PM

I can't say I've used the packs from Hobbycity, but it's been my experience you get what you pay for. Now that 25c is the norm that's all I'll be buying now, or 30c min too. I've swelled a few packs of lesser quality and had to throw them away so it was money not well spent. Fusion packs have done me right so far and they're less than Thunder Power so I'm sticking with the medium priced packs. With batteries sometimes it's better not to cheap out, you'll just be cursing them after a few flights! 3D especially is hard on power systems so I tend to try and get the best stuff I can afford so I don't end up having to re-buy items later or worse yet end up re-kitting a plane because of power failure. I think the rule is: Pay up front or pay a lot more later!:eek:

Originally Posted by HugoW (Post 486536)
I'm finding these:
https://fusion-pack.com/productdetai...id=158&cat=116

But they are over a 100 bucks more and 700mAh less. Undoubtebly better quality, but I doubt the difference is worth it.

Or am I looking in the wrong direction?

Cheers,

Hugo


HugoW 10-08-2008 07:17 AM

Well, I've taken a bit of a gamble. Since I needed an assortment of other bits and bobs of them, I ordered one pack allong. I'll put it through it's paces on the bench and see what we have. Worst case I spent 74 bucks on a battery I can use to poodle around with (the Funtana on low rates would make a nice sunday-afternoon-in-the-park flyer). If they turn out to be fully useable (20C @ 4Ah is 80A discharge capacity, right?) I might order some more.

For bench testing; would it be safe to say rigging the motor/prop/esc/etc up statically makes it run higher loads then in flight? I think I read that somewhere, but I'm not sure.

Cheers,

Hugo

EDFrules 10-08-2008 12:43 PM

Bench testing is fine for reference sake but you'll find that once it's up in the air and you start 3D'ing it, the system will start to heat up a lot more. During hovering and high alpha stuff there's a lot less airflow over your components than during level flight. Things tend to get hotter quicker. A quick temp check after the first few flights should reveal how the system is reacting. Good luck and keep 'em flyin'!

Greetz,
Jason

HugoW 10-08-2008 01:01 PM

Ah, OK. I'll set up the bench test such that I can keep the LiPos out of the airflow, see what happens. Eagle Tree is tempting...

Oh, and before I forget; thanks for all the input! I really learn a lot, and injoy it.

Cheers,

Hugo

EDFrules 10-08-2008 02:07 PM

Just make sure you don't run the entire pack sitting on the bench. Saw someone do that and he wondered why his packs were so swollen and useless. ????15-20sec. is about the most you want to try full throttle without any good airflow over system. Should give you a basic picture on your wattmeter. The best test is to just fly it!

Greetz,
Jason

HugoW 10-08-2008 03:09 PM

I learned that in a similar project; fitting a turbo to a car. The tech I was working for bench-tested the engine I built at full throttle for a full minute, and blew the engine in a rather spectacular way. And in real life, if you go hit full throttle you'll run out of RPM in say 15 seconds...

I'm looking at the Watt's up meter:
http://www.rc-electronics-usa.com/am...amp-meter.html
wondering whether I can ditch the housing in clear shrink tube to save some grams.

Cheers,

Hugo

EDFrules 10-08-2008 09:44 PM

Save some grams? This wattmeter is just for ground testing, doesn't record inflight data. Eagle Tree would be the best for inflight testing. Or you can use a Hacker Spin ESC, it records inflight data recoverable on the optional Spin Box. I use a Spin 99 on my Extra but everyone says it's not very accurate. I just use it for reference sake. Eagle Tree is the way to go for inflight data recording. That's where the rubber hits the road, or should I say the prop beats the air....

HugoW 10-09-2008 05:57 AM

Well, my main objective was to check max amps, and see how much was drawn from the pack. Both are recorded on the Watt's Up. But the Eagle does look interesting, too. I would like to optional screen, though, carrying my PC and monitor to the field (with a looooong extension cord) woul'd become tiring after a while, I guess.


All times are GMT +1. The time now is 06:15 AM.

Powered by: vBulletin
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.05130 seconds with 7 queries