Hello gentlemen,

first some info about my current project:

I got myself used Energic hotliner, its 2450mm wingspan and I am looking at 2200g AUW.
Previous owner cut the nose a lot so I will need 40mm diameter spinner now.
I want to use geared scorpion outrunner HK-3026-1400KV which has 5mm shaft. That is why I am thinking about using Reisenauer Super Chief gearbox which is made in various gear ratios from 4:1 to 8:1.
They are already selling combos and have very interesting measured(?) data which are unfortunately very different from calculation I can do in eCalc.

http://www.reisenauer.de/artikeldetails.php5?aid=1113

I want to get into 100-130A range at 8S with some easily availaible carbon prop (which for me here means only RFM prop I am afraid).
My question is what gear ratio I should choose to get similar performance with my 1400KV scorpion as they get with 1900KV and 6:1 gearbox?
I know that just mathematically I should get to 4:1 but 1400KV scorpion is 10poles with different winding than its faster 1600KV and 1900KV brothers.

Here are numbers for 1400KV hyperion but with 6:1 superchief gearbox

http://www.reisenauer.de/artikeldetails.php5?aid=1461

and the results are IMHO too low/slow for me and the prop used have to be too big as with the shorter nose on my Energic I am limited to smth like 19inch folder prop. (RFM biggest square prop is 16in anyway)
All these components are not really cheap so I wish to nail it good with the first shot.
Please can someone experienced give me advice if I can get away with 4:1 or if 5:1 would be enough for my expected 3kW+ and as fast as possible drive but still with enough of static thrust for easy launch?

Thank you

ok. seems like nobody went this way yet making me sort of pioneer, right?

anyway there is one more thing which puzzles me with the scorpion motors.
it is labeled 1400KV but when I measured it with eagletree rpm sensor and then again opticaly with laser tach I got in both cases almost ideantical 1580KV on both motors.
I did try from 2S to 4S but the result was always the same.

is this normal or did I do smth wrong?

I remember, there was a bunch of wrong labeled 3026 a while ago.
Check out the poles, the 1400 is an 8 Pole, the 1600 is a 6Pole.

Andy Reisenauer mesures all his drives at a Dyno which is quite accurate, but with square or oversquare props static tests may give some differences.

Usually i get some higher logreadings in amp and power than the dyno gives,but i usually preheat my lipos to 40°

There is a new smaller reisenauer gearbox which may be able to handle your powerlevels,
But its only available in 5:1 and with 3,2mm shaft.

I shortened a 3026 to 3020 for this gearbox( but did not try it yet),its simple to change the shaft to a stepped 5-3,2 mm shaft,Andy may be able to help you if necesary.

Yello

Thank you for valuable info.

number of poles = number of magnets in rotor, right?

I did check my motors and both of them has 10 magnets so it should be 1400KV.
so dunno why I measure more.
(actually the 1600KV and 1900KV versions are 8poles and 1400kv is 10poles)

with the new gearbox you meant the new micro edition 4plus with the square front?
I read about it some time ago but it did seem so tiny, but... up to 4kW for 5sec is more than plenty for me.
It is cheaper too and it doesnt have the oval 6x7 output shaft which was giving me headache when thinking about other than reisenauer yoke.
Overall it is looking good as to machine the 5mm shaft to 3.2 should be easy here.
I cant find proper flange and pinion belonging to this one though.

I will ask the shop by email directly.

thanks again

3+kw seems an awful lot for a 3026. A drive like this is not very common, so that's probably why you're not getting much help here.

I dont know anything about the "hole distance" of the scorpion but the first thing thats comes to my mind if i read 5mm shaft is the Axi PG433 4:1 gearbox. With 1400KV and 4:1 u wont end up with such a large number of cells too

Recodring to ecalc.ch I would use this setup as a starting point:
7S 2500 , 3026 1400KV / 4:1 AXI PG433 , 16x16 , 0° RFM Spinner
= 9700g Thrust , 4000kg Stall Thrust , Eta : 77% , 2,6kw in 2kw out
I know that u want to hit the nail in one step but if you are really the first one to test u have to test different props and cell numbers..

Originally Posted by Steve C

3+kw seems an awful lot for a 3026.

Not really,
I use the 3026-1400 at 2,2 Kw in a speeder up to 50sek.
I also use the 2221 (which is less than half the weight) and 5:1 geared with up to 2,5Kw in standard version and over 3Kw custom winded for short hotliner bursts.

I am more worried about the rpm at 8S than at the watts.

Yello

A friend just ran one in a speeder with good cooling at about 1000 watts and after landing the motor was 176F. I'm surprised the thing can handle so much more, but I'll take your word for it.

And how was the motor mounted? Like the german speedguys do it or behind the firewall?

The number of cells is what I choose cuz I want the power it can deliver without the enormous current surge. There is enough space in the fuse for the batts as well.
In another words I wish to stay within ESC current spec and at the same time I dont want to spend fortune on branded 200A+ ESC either (and I am not far enough to flash chinese 200A ESC with special F5B fw yet).

When they can get away with 5sec on 8S at HK3026 with 1900KV it should be easier with 1400KV. The ESC I have is rated at 240kRPM for 2poles so with 10poles I should be ok up to 48kRPM and 8x3.8x1400 (even my measured 1580) makes 42560RPM (48032) but thats completely unloaded. OK, it is close but should work IMHO.

Anyway my original and probably naive idea was to make that drive from 6s to 8s capable. Light 6s for more soaring and heavy fast at 8s using combinations of 3s and 4s batteries.

Honestly when my HV ESC arrived week ago I could not fit it into fuselage without mods so maybe I will end up with small 100A ESC at 6S only.

The mounting holes on the motor are 25mm so the axi pg4/33 would fit perfectly and its really cheap but at the same time its written to be up to 1200W.
I know its still better than NO number on KPG gearbox but isnt it too little? What will happen when the gearbox give up?

I dont think eCalc is good for oversquare props. In this I will trust more to the measured data from reisenauer.de.

Other thoughts:
when the idea of step down shaft appeared here.. I can even use the KPG25 I have already and see what happens, just need another pinion and flange for kira500/600. On the other hand I can not find any info (not even here on RCG) how much power KPG gearboxes can withstand.

Decisions, decisions...
when I get tired from overcombinating I will settle down with 6S small 100A ESC step down shaft and KPG 5.2:1

but Thanks for input guys

Hey!

I miss your ESC Specs i think it should be a CC Ice 120HV or something like that?
The chinese GX200A /Red Brick 200A aren't that bad without FW flash. Mine works without a flaw at 2kw same as the AXI Gearbox. The only thing that destroys a Gearbox for sure is hard brake with big props. You should simply avoid that.
The older Axi GB could take more abuse but the newer ones dont I heard but I think at 3KW with soft brake it should hold up. The axi gb's normally die because the tooths shear off. Its clear that you should install a seperate RX battery at these powerlevels to avoid a total loss.

I'll test some new configs with 8S and let you know later.

The only two hig performance RFM screws that fit a 40mm spinner i know are the 16x16wide and 16x17S. I'd go for the Wide prop because the S allways generate noise through vibration and are not very efficient.
With the 16x16w you have 2 options:
1.) You go 8S with a KPG 4,2:1 (I hope you can find one) or Axi PG433. Current recording drivecalc will be around 112A. So this setup gives you about 3Kw , 180kmh vpitch and sufficient thrust.
2.) You go 8S with a KPG 5,2:1 or Microedition. This setup will be less powerful but much longer run times. You can fly longer and dont have to watch at the 3S max Motorruntime.

Remember these are theoretical calculations. This can differ much from flying results but you have a guidline. I think both will be much fun and if this is your first real composite hotliner they will be more then sufficient for a grin on your face :P

Originally Posted by Tzeentech

And how was the motor mounted? Like the german speedguys do it or behind the firewall?

It was mounted about 20mm back from the firewall, with cooling inlet in the bottom/front and exit behind on top. I know the cooling worked ok because the temperature rose up on the outside of the motor about 30F after landing.

I didnt want to mention the ESC here but when you ask... I have the chinese YGE knock off so its rated 4-14S, 120A continuous and 140A peak... and its really huge

I was thinking about the mystery/redbrick 200A but after what happened to my last airplane I would like to play it more safe this time.

Even with the shortened nose I am still thinking about going back to 38mm spinner, I already made CAD drawing for special metal firewall which will extend the nose a bit and get me from 40mm back to 38. I am looking for someone who will do it on lathe now. Dunno if its a good idea when comes to structural integrity but I could not come with anything better when I wanted to use the special RFM spinners as only with them you can use the oversquare props in 17'' and 18'' diameter.

Bad is that I have to buy all the props I want to test the drive with as the only local seller of RFM (I know of) dont have them in stock unless someone order it. And as you mentioned those number are only calculations and I believe I can get more than 50% away from it IRL. Still have to start somewhere, right?

This is really valuable info so I have to be careful with the brake setting too. I have extra LiFe RX battery prepared though it will be with separate BEC as I couldnt find wing servos in reasonable price range which would be precise, good centering, slop free and 6.6V capable at the same time.

To get KPG 4.2 is easy, for example here http://horejsi.cz/Pages/DetailProduk...?objcislo=1844 which is about 5min away from my office.
My question is which gearbox is better for higher power loads if AXI or Kontronik.

Probably will go for the drawer stock which means KPG5.2 and RFM15x15 to get some inflight data first and then see where to move cuz only the RFM spinner and prop is almost 2kCZK.

I have to think it over once more so I will know more in the morning

Originally Posted by Tzeentech

1.) You go 8S with a KPG 4,2:1 (I hope you can find one) or Axi PG433. Current recording drivecalc will be around 112A. So this setup gives you about 3Kw , 180kmh vpitch and sufficient thrust.
2.) You go 8S with a KPG 5,2:1 or Microedition. This setup will be less powerful but much longer run times. You can fly longer and dont have to watch at the 3S max Motorruntime.

I could not get those number out of my head.

In the morning I have downloaded drivecalc which should be much better than the web ecalc I was using till now.
But as first time user I could not get any result for the first combination. It gives some reasonable numbers for 5.2:1 but not for 4.2:1 probably thinking it is way out of spec just as ecalc does.

How did you do it?

Lol I also have exactly those two ESC's. The YEP will be tested in my Speeder which will be powerd by a Powercroco. Did you get any manual with it?

Hmm thats what people do if the want high pitch props on the FVK Kamelot because it also has a 40mm Spinner.
I looked closer at Reisenauers configs and i cant reconstruct them. They differ by far. If i calculate his HK3026 1900kv with 6:1 setup with 3,5/cell I get almost 20A more than him.

You can abuse that YEP with 140A for a few seconds. I would really start with the 16x16W and then look for used props on ebay or forums to prop up. If you want to save money mount the 17x18 5° with 5,2:1 KPG should work but throttle on a switch and not more then 2-3Secs Motorruntimes. And remember cooling phases between throttle phases!