And do yourself a huge favor....never rush the landing with this plane tell you have it wired,leave enough lipo on the first flights to go around 5 times if you have to for a cherry drop in....She does not like hot landings with a cartwheel at the end but once you get the hang of it,it will land soooooo easy.....Remember,this thing was built LIGHT and will take any stress you give it in the air...but it does not like doing battle with the ground.

Originally Posted by Ben D Wing

Quite a big difference in 3 or 4s set ups with regard to speed. If you are a very experienced pilot then go straight for 4s, otherwise 3s is highly recommended. The most popular motors are either a HET 2W-20 or a Mega 16/15/3 as both are happy on 3 or 4s and are both an excellent choice with the Mega being the better quality. I'm using the Mega on 4s with an APCe 5.1 x 4.5 and it goes like stink! Circa 150 MPH? The HET can be pushed more and one UK show pilot claimed about 180 MPH with a HET on 4s, but I'm not sure what prop size he was using. Any idea Feefo?

On motor or prop?

An idea I'm floating about is returning my 16/15/3 and having it changed to a 16/15/2.5R, kv would be 3500kv, Mega rates it at 40a.

A motor calc gives estimates of 41a, 31989rpm, 144mph pitch on a 3s with a 4.75x4.75.

On 4s and a 4.1x4.1 then the calc reckons 38a, 44518rpm and a pitch speed of 172.8mph.

Motor calc claims efficiency to be around 85% on 3s and 88% on 4s. Not sure...

But the volts under load is a little low on the calc, max it predicts is 10.5v, personally I'd expect a litlle higher, especially if using a high rated C pack so the figures could be out. Not too much prob with a 3s pack as you could lower the prop size to compensate, but you might not have anywhere to go on 4s, although it's a Mega and should be fine.....

I guess the HET 2W-18 is the copy of the 16/15/2.5R.

Other than that my opinion would be the 16/15/2, run on either 2s or 3s. I like the idea of a lighter setup with a 2s, which makes squeezing everything in easier. But the 16/15/2 seems to need better packs (and a bigger esc...) as amp draw is that little bit higher over the 'predicted figures' of the 16/15/2.5R.

Awesome guys, thanks for the input ! Looks like I am going with a Mega16-15-2 on 3S , 1250 mAh Thunderpower or larger... This one is for a friend, mine will also have the same
setup ! I'll keep you all posted !

The maximum sized 3s I managed to shoe horn in to the Voodo was a 1600mAh. The largest 4s is only a 1000mAh. It really is tight in there so good luck with the build!

Tim, have you built yours yet?

Did you buy the Zippy Compact 1500 3s and does it fit? Any chance you can measure the wing saddle plz? Battery choice is the only thing holding me back.

Originally Posted by feefo

Tim, have you built yours yet?

Did you buy the Zippy Compact 1500 3s and does it fit? Any chance you can measure the wing saddle plz? Battery choice is the only thing holding me back.

What measurement would you like to have done? I might be able to help you.

/Håkan

Feefo, I can get a Zippy compact 1000mAh 4s in, or a 45-95C 3s Nano-Tech 1300mAh.
Both only just fit as my ESC sits on top of the battery.

Such itty little batteries.


Click the view attachments thing (under thread tools - top right) and look at the pics of previous builds, its possible to get much larger packs in. 1800 Vx G3 3S hyperion packs fits easily for instance, one guy was running a 3S 2100

EDIT

Itty little batteries equal a light weight plane with superior acceleration and better slow speed handling qualities.

Originally Posted by feefo

Tim, have you built yours yet?

Did you buy the Zippy Compact 1500 3s and does it fit? Any chance you can measure the wing saddle plz? Battery choice is the only thing holding me back.

I've got it mostly built up, servos are in, there's really not a lot to do. Just waiting on the Mega 16/15/3 to turn up now to finish it. I've used 3 Hitec HS 5035 HD servos which are miniscule and only 7.6mm thick. They've got good centering, no play in the gear train and are quick compared to the D47 which I was going to use for the ailerons, couldn't find any of the quicker D47S in stock in the UK. The control surface areas and deflections are tiny so not worried about the in flight loads on them. Will post a couple of photos soon.

I've got a couple of the Zippy Compact 1500 3S. Fit very easily with the servos in the standard location as they're only 14mm thick. Also got some 35C 1000 mAh 3S which I'll use for the first flights. You just need to keep the battery thickness below 18ish mm if you using the standard servo location.

I made a mock up of a Mega 15/7 motor at 48 grms to see if it would balance OK with a 3S 1000 mAh and it's fine provided the battery is under the ESC and pushed well forward. I'm still half tempted to try a 15/7 Mega in it for an ultra quick turning, very light set up, should be less than 350 grms.

Fantastic quality airframe, I forgot to say.

Originally Posted by hakank

What measurement would you like to have done? I might be able to help you.

/Håkan

Length of opening, width of opening at TE and width of wing bolts, Thanks if you can.

Originally Posted by jackosmeister

Such itty little batteries.

Click the view attachments thing (under thread tools - top right) and look at the pics of previous builds, its possible to get much larger packs in. 1800 Vx G3 3S hyperion packs fits easily for instance, one guy was running a 3S 21000

Checked attachments and looked at photo's many times, inc your post of the 4 batteries and your conclusion that even with resoldered wires it was difficult to get some in. The G3's you used look ideal, just looking at HK alternatives.

I'm not trying to stuff in the biggest battery in I can, but would like something that will give me enough run time depending on what motor I decide to go with. I'm not convinced the 16/15/3 will satisfy my needs on 3s, if it would, battery choice would be easier.

Originally Posted by Ben D Wing

Itty little batteries equal a light weight plane with superior acceleration and better slow speed handling qualities.

I know....


Cheers for the info Tim, I've used the Zippy Compacts in other planes, the 4500mah 4s 35c I have holds it voltage under load really well, I've been impressed with them.

just ordered 2x zippy 4s!
its gonna be fffffast!!

Originally Posted by feefo

Length of opening, width of opening at TE and width of wing bolts, Thanks if you can.

111mm, 31mm and 28mm (smallest distance between sides, not wing bolt centres). I think those measurements aren't particularly critical as you have to tilt the batteries over to get them in. It helps if the batteries are narrow as well as thin (33mm or less is good) so they sit closer to the bottom of the fus.
Maybe a good idea to wait until you've got the fus in your hands and play with some mock ups if you're looking at putting in some biggish batteries.

Cheers Tim, the 33mm wide bit is useful.