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e-Electric Conversions > Help with conversion!

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Hello!

can anyone help me out with which engine to use in a converted
60 sized Graupner agusta, orginally the heli was run with a 60 Os
Im planning to run it with 10-12 cells lipo and the flying weight is gone end up with approx 6kg, been in contact with graupner in germany due to to the purhase of their Skalarmechanics but as I see it they just want to sell without any support.

Thanks

/Jack

10-18-2007 06:50 PM

garyl
Senior Heliman
Location: taxachussetts

Try this calculator. There are alot of variables which will determine what motor and batteries you will need.

[url=http://www.scalerchelis.com/phpBB2/viewtopic.php?t=6071]

10-18-2007 07:23 PM

JKos
Elite Veteran
Location: Town of California in the state of Maryland

I bet an Actro 32-3 on 10S is a good place to start.

- John

Protos -- Logo 14 -- Logo 10

10-18-2007 07:39 PM

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Thank Guys

tried to download the calculationsheet but gettin a error messagen when trying to close it and wonder if this ok, for now I must use ctrl,alt delete to close program and windows is asking if to sent a error message?

Cheers Jack

10-19-2007 05:39 PM

garyl
Senior Heliman
Location: taxachussetts

Did you try the Excel spread sheet SRCH_Eflight_excel_V1[1].6.xls file?

The other file is a .zip file for downloading a program.

10-19-2007 07:07 PM

fergus
Veteran
Location: Ireland

Instead of the calculators you could do the maths yourself. It helps when trying to understand how the figures are arrived at:

If you can give more specific details of your setup then I could try and illustrate the figures for you.

Main gear count?
Gear ratio?
Required headspeed?
Weight (Both for 10s and 12s)? Just quote your current heli weight without engine or clutch.
Required flight time?

With this information then your options can be easily laid out and you can make a more informed decision. If you have this information I will try to explain further.

Regards

Fergus

10-19-2007 07:34 PM

fergus
Veteran
Location: Ireland

Ok jack,

I just did some checking on the mechanics you are using and it shows gear ratios of 6.75:1 or 7.71:1.

The manual shows two motor pinion gears:

part no. 4475.07 28teeth
part no. 4475.08 32teeth

With this info you can now establish what motor KV you require for either 10s or 12s

12s seems out as for either pinion gear your headspeed will be way too high for a scale setup

10s:

37volts * 415 (Kv of Actro 32-4)= 15355 (motor RPM) / 6.75 (gear ratio) * 0.8 (efficiency)= 1820RPM

This is too high for a scale setup. The Actro 32-3 has a Kv of 555 which would give an even higher headspeed of 2400!

Really for a 10s setup a smaller pinion is needed if you want to use an actro motor. Either that or lower the cell count.

In considering the cell count option you must factor your amp draw as this will effect flight time for a given capacity and also generate heat and if this is too high you will burn out components!

Allowing a peak of 130watts per Ib for scale flying. 13Ib (6kg) means 1690 watts peak

watts = Amps * volts

For 10s 1690watts/37volts= 45.9 amps peak.

100watts per Ib hover = 1300watts

10s 1300/37=35.1 amps average

Thats about 6 minutes flight time for a 5000mAh pack. Much higher amps will reduce this flight time so I think 10s would be the best option.

I think you should enquire about other pinion gears with lower teeth counts before you decide on a motor and power setup!

I am not familiar with the Graupner mechanics so maybe someone else will chime in with the answer on availability of other pinion gears.

Regards

Fergus

10-19-2007 09:57 PM

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Thanks Fergus for yours detailed answer, last days have been "learning" days and for now im hunting a motor that will fit, as you say a pinionchange is not out of question, did a search here on RR and found a post wherea chap had a converted 60 Agusta with
Graupner Uni mechs and a Kontronink Tango 45-06, Kw 600 way out to much for mine pinion so for now im searching for lower Kw,s.

Thanks again Guys!

Cheers Jack

10-20-2007 06:43 AM

fergus
Veteran
Location: Ireland

Jack if you went 10s with the actro 32-4 as per the previous example then you could govern it down to an acceptable level. 1800rpm is not excessive but would not give a very scale like performance.

To do this I would only use a Kontronik ESC as they have a great governor mode. The Jazz 55-10-32 would do the trick nicely.

I have been able to run headspeeds all the way from 1300 to 1850 on my Joker 2 on 10s lipos using this ESC. It is not something I would advise with other ESCs as most need to run near 100% but the Jazz does not seem to be bothered by using a lower %.

If you do a search here on the Jazz governor mode you will see what I mean. Still a motor pinion change would be a better option than using the electronics to vary the headspeed but you may have no option.

Also check the diameter of your motor shaft before you buy as the actros come in two sizes.

Best of luck

Fergus
p.s here is another motor pinion calculator if you need it:

http://www.bladebusters.com/calculator.html

10-20-2007 01:03 PM

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Fergus!

Did some counting

With the 28t pinion the Gear ratio is 7.71

54/28=2,7 x 60/15=4 2,7 x 4= 7.71 Gear Ratio

37x415 (Kv of Actro 32-4)= 15355/7.71 = 1991 X 0.8 = 15925 Rpm

or have I done something wrong with mine calc, 1600 rpm seems fair
for a 60 scale or im I thinking wrong here?

Cheers Jack

10-20-2007 06:49 PM

fergus
Veteran
Location: Ireland

Good catch Jack I had divided by the other gear ratio of 6.75 and never thought to check the 28tooth ratio for you.

That would be a respectable headspeed which if used with a Jazz ESC you could lower slightly to get a more scale like performance.

Looks like you found your motor!

Regards

Fergus

10-20-2007 06:58 PM

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Thank for that fergus, now mine evening is done

could you maybe point out where to buy here in europe, germany, England or other country?

Cheers Jack

10-20-2007 07:02 PM

fergus
Veteran
Location: Ireland

Revolutionmodels in England stock the Actros

http://www.revolutionmodels.co.uk/acatalog/Actro.html

Also Gerd at minicopter has them if you prefer euro

www.minicopter.de

Make sure you get the correct diameter motor shaft for your pinion (8mm or 5mm)

I am sure there are more but I have dealt with both of these suppliers and find them great to deal with

Regards

Fergus

10-20-2007 07:19 PM

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Thank you Fergus, another"problem" ouestion.

supplied with the skalarmechs from Graupner was a motor pinion holder, the problem or maybe not is that the graupner motorsshafts are 6mm, when assembled with the adapter and the hexagon nut the dia is about 5,60mm, when the nut is unscrewed the dia is slightly over 6mm,designed for the original graupner shafts, as I understand the Actro comes with 5 or 8 mm shafts, as I see it 5 should be to small even when the nut screwed on to the maximum and 8mm is to thick, is it possible to get 6mm shafts to the Actro or could there be another solution to this, would greatly like to use the original pinionholder as it is designed for the pinion supplied with the mech.
Also noticed that the 32-4 comes in a "Max"version and are a little more expensive.

Cheers Jack

10-20-2007 08:09 PM

fergus
Veteran
Location: Ireland

Maybe PM the guy who had the Kontronik Tango motor fitted in the same mechanics which you refered to earlier. They also have a 5mm motor shaft so he may have faced the same problem!

Have you considered one of the Graupner motors you mention instead of the Actro? I don't know anything about them but might solve alot of headaches. I checked the site but nothing springs to mind.

I don't think the Actros are available at 6mm. I have no experience of the max version of the Actros I'm afraid.

You could contact Graupner again and you might get a more helpful employee who could advise you better! Ask what motor they advise for this heli.

https://shop.graupner.de/webuerp/servlet/AI?ARTN=4475

This seems to be a pod and boom with your mechanics set called the WP ELEKTRO SKALAR. The motor options seem to be for 5/6s packs though.

If you post the same question about the pinion in the Scale or motor section here you might get more help. I find things can be a bit slow in this section at times.

Regards

Fergus

10-20-2007 09:12 PM

fergus
Veteran
Location: Ireland

Jack you could send Sandy at v-east a mail. He sells Graupner in the USA and is meant to be great to offer advice and help

http://www.v-eastonline.com/

Regards

Fergus

10-20-2007 10:00 PM

Jack Söderberg
Senior Heliman
Location: Gothenburgh, Sweden

Thanks Fergus, have been in spoke with a friend that is a mechanical
guru with lots of tools and machines and he told me that the 8mm shaft
can be adapted to the origin pinion holder with a special machine that are rotating(dont know the name in English)down to 6mm.

think this gone end up well in the end, do you maybe know the diff betveen the max versions of the Actros (called 32-4 helimax and some moore expensive)compared to the 32-4?

Cheers Jack

10-21-2007 07:02 AM

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