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Old May 10, 2014, 05:16 PM
Jet-Set !
xenon20's Avatar
United Kingdom, Clevedon
Joined Dec 2013
149 Posts
Help!
Choosing fan/motor/battery/esc for my air frame

Hi all

I'm building a 90mm Saab Viggen from D_Fast's plans in the EDF scratchbuild forum.

I'm afraid I don't know where to start with this. I did some calc's last night and reckon that my empty finished model will be about 1.5kg. I tried to estimate the AUW based on an 8S battery (?) which I estimated at roughly 3.7kg.

I am looking to fit a 90-100mm unit with a fairly realistic turbine sound. I already have 3x 4S 2200mah 35-70C lipo's which I would like to use if possible to save some cash.

What is the first step towards choosing a fan / motor / battery / esc combo ?

Lost on this so any advice is greatly appreciated

Thanks

Paul
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Old May 10, 2014, 05:29 PM
Registered User
cbear's Avatar
jacksonville florida
Joined Feb 2005
377 Posts
Gary at e flux is who I went to, lots of choices. I, went with a jetfan 90 and het 700-68-1400 for my jet, figured I could use this on 8 or 10 c with a yep 120 hv speed control with the option to move to another jet in the future, some people go a different route, if you click on the jetfan 90 page on his sight it shows charts for each cell count and thrust, kind of put you in the ball park
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Old May 10, 2014, 05:32 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,402 Posts
jetfan 90
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Old May 10, 2014, 06:05 PM
Jet-Set !
xenon20's Avatar
United Kingdom, Clevedon
Joined Dec 2013
149 Posts
Unfortunately I don't think the jetfan 90 is available in the UK ?
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Old May 10, 2014, 07:43 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,402 Posts
Get it right from Rainer.

http://shop.ejets.at/en/Ducted-Fan

Austria can't be to far away!
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Old May 11, 2014, 03:10 AM
Jet-Set !
xenon20's Avatar
United Kingdom, Clevedon
Joined Dec 2013
149 Posts
I was on there last night but wasn't sure if they would deliver to me, so you own one ? What else have you owned and how does it stack up? What is it about it that makes you have so much praise for it? Please convince me to buy one !

Many thanks

Paul
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Old May 11, 2014, 05:04 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,402 Posts
Quote:
Originally Posted by xenon20 View Post
I was on there last night but wasn't sure if they would deliver to me,
Can't see why not? He has shipped to the USA.

so you own one ? Yes, and I will need one or two more

What else have you owned and how does it stack up? Dynamax, sold it to buy a Jetfan, decided to stick with 90mm sized fans. I never considered any other fan.

What is it about it that makes you have so much praise for it?
Excellent quality and workmanship for a fair price!

Please convince me to buy one ! Convince yourself, at least read the last 20 pages-- http://www.rcgroups.com/forums/showthread.php?t=1504718.... New JETFAN-90, or " The sound of silence?"

Many thanks

Paul


Cooler
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Last edited by CoolerByTheLake; May 11, 2014 at 05:11 AM.
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Old May 11, 2014, 06:18 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
5,402 Posts
Paul,
Check out the videos in these posts, planes are a touch bigger than your Viggen, but you get the idea.

http://www.rcgroups.com/forums/showp...&postcount=545

http://www.rcgroups.com/forums/showp...&postcount=628

http://www.rcgroups.com/forums/showp...postcount=1506


You also mentioned ESC and Batteries. A lot of guys have bought this ESC, I have 2 myself. (Good price couldn't help myself.)
Hobbyking YEP 120A HV (4~14S) Brushless Speed Controller (OPTO)

http://www.hobbyking.com/hobbyking/s...ler_OPTO_.html

Check here for a buddy code and save a few bucks. http://rcsearch.info/hobbyking/buddy/?strSearch=yep
You need to be signed in first to see discount price!!!


As for lipo's, you should be closer to 4400/5000mAh on 8s
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Old May 11, 2014, 08:15 AM
Jet-Set !
xenon20's Avatar
United Kingdom, Clevedon
Joined Dec 2013
149 Posts
Thanks for the links.

So would my two 4S 2200mah packs (8S 4400mah total) not be up to the job then?
You mean I would need 2x 4S 5000mah (8S 1000mah total) ?

Ok so lets assume the following:
3.2kg AUW
Jetfan90-V2
HK YEP 120A HV controller
HET 700-68-1500 motor

So how do I calculate what battery is required?
Been looking at fancalc, motocalc etc but confused
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Old May 12, 2014, 07:26 AM
Registered User
MagnusEl's Avatar
Sweden, Gävleborg County
Joined Jan 2004
851 Posts
With two 4 cells 2200 packs you can not get 8s 4400, only 8s 2200 if you put them in series, or 4s 4400 if you put them parallel.
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Old May 12, 2014, 01:10 PM
Jet-Set !
xenon20's Avatar
United Kingdom, Clevedon
Joined Dec 2013
149 Posts
Hi

Ok I've done a bit more research and I'm a (little) bit more clued up now.

I have done a new fancalc calculation (see attached) based on 2 4S 2200 packs connected in series to make an 8S 2200 35-70C pack.

I don't understand all the results but I was playing around with battery and motor combinations to see what would give me a thrust-weight ratio
of around 1:1. It seemed by uping the pack capacity to higher mah ratings were not making much difference to the thrust-weight ratio.

Could all you experts advise me what the most important data is when looking at my fancalc results, and whether the attached setup looks ok ?

Many thanks

Paul
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Old May 15, 2014, 12:26 AM
Aircrafting is noisey...what?!
charlieoneseven's Avatar
United States, CA, Long Beach
Joined Dec 2005
585 Posts
The higher mah gives you longer flights and higher cell count makes the jet faster at wot.
Have fun what ever you go with. The nice thing is everything is swap able so if you don't like one try another. The jet fan is the coolest thing going out here as well but others are still spitting out plenty of sky.
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