Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
May 29, 2020, 10:18:53 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Electric power for Scale Models  (Read 421 times)
0 Members and 1 Guest are viewing this topic.
vintagemike
Silver Member
****

Kudos: 9
Offline Offline

United Kingdom United Kingdom

Posts: 201

Topic starter


Ignore
« on: April 01, 2020, 07:31:17 AM »

Hi Guys, this might have been asked before if so sorry. My question, is there an electric motor set up, ie fairly complete so that an idiot like me can use it that provides the same power as a DC Dart .5cc diesel and can swing similar size props. I am thinking of building something from the Aeromodeller plans catalogue but want to go different with the power. UK based so preferably available over here. Thanks, Mike 
Logged
alset
Bronze Member
***

Kudos: 2
Offline Offline

United States United States

Posts: 73



Ignore
« Reply #1 on: April 01, 2020, 11:54:01 AM »

I don't know the answer.  But the three biggest problems I see when converting a plane to electric are
1) What electric power to use?
2) What prop?
3) Where is the balance point?
If there is a source for these I would like to know. Experienced builders, of course, just have a knack for knowing these things.
Logged
ironmike
Platinum Member
******

Kudos: 89
Offline Offline

United States United States

Posts: 1,184



Ignore
« Reply #2 on: April 02, 2020, 09:19:05 AM »

I fly a lot of e powered scale.

What I have found is:

CG is located about the same as rubber power would be located.
most effective models are in the 24"-36" span.
I prefer using the GWS stick geared motors (KP-02) since they allow a range of props, also cheap.
Props are in the range of 6"-8" dia
Down and right thrust needs are usually less than that on similar rubber models.
If available I use small ni cads rather than other battery types. Easy  to control engine run times.
5 to 6 ni cad cells (6-7.2) volts
Short nose WW1 type models love electrics
Logged
3view
Silver Member
****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 211



Ignore
« Reply #3 on: April 02, 2020, 11:44:28 AM »

Hobbyking 18-11 2000kV (10g) brushless outrunner
6A brushless speed controller
250mAh 2s Lipo
KP time and speed controller
7x3.5 electric prop

You'll need a lipo charger if you haven't already got one and and connectors to suit.
Logged
charlieman
Gold Member
*****

Kudos: 5
Offline Offline

United States United States

Posts: 283



Ignore
« Reply #4 on: April 04, 2020, 10:08:54 AM »

Don't want to twist anyone's knickers Roll Eyes, but I've asked this question a number of times, over last 10-20 years.  It's been my observation that there is a bit of snobbery, from E practitioners. Seems to me they go off on weights and formulas, well beyond the ken of this modeler(65 yrs experience).  I don't want to be a rocket scientist or re-invent the wheel. I only want a simple recommendation of a motor/prop/battery and possibly an esc for a given type and size model.  Sure seems to me that the E crowd has benefited greatly from the gas/rubber scale tradition and experience, but apparently doesn't want to explain basics to  old school guys like me.  Grin



Logged
billdennis747
Palladium Member
********

Kudos: 60
Offline Offline

United Kingdom United Kingdom

Posts: 4,031



Ignore
« Reply #5 on: April 04, 2020, 11:18:05 AM »

I've pm'd you the text and a couple of photos for the system I use in a 33" model which I might otherwise have used a 0.5 diesel. These were in Aeromdeller August or September 2019.
I haven't a clue about electrics and this was the sole result of help from a friend who knows his stuff. I suggest you follow this but you will find that the products seem to change every time you look on Hobbykings website.
Here's a video to show how it flies

https://www.youtube.com/watch?v=FDmMjmT5Sio

Bill
Logged
3view
Silver Member
****

Kudos: 15
Offline Offline

United Kingdom United Kingdom

Posts: 211



Ignore
« Reply #6 on: April 05, 2020, 03:55:42 AM »

Don't want to twist anyone's knickers Roll Eyes, but I've asked this question a number of times, over last 10-20 years.  It's been my observation that there is a bit of snobbery, from E practitioners. Seems to me they go off on weights and formulas, well beyond the ken of this modeler(65 yrs experience).  I don't want to be a rocket scientist or re-invent the wheel. I only want a simple recommendation of a motor/prop/battery and possibly an esc for a given type and size model.  Sure seems to me that the E crowd has benefited greatly from the gas/rubber scale tradition and experience, but apparently doesn't want to explain basics to  old school guys like me.  Grin

Things were a lot easier when we could get Nicads.  Nicads/ brushed technology was perfectly adequate for our needs.

Shall we start a new thread that could be made a sticky? That lists proven electric setups suitable for free-flight?

Steve

Logged
vintagemike
Silver Member
****

Kudos: 9
Offline Offline

United Kingdom United Kingdom

Posts: 201

Topic starter


Ignore
« Reply #7 on: April 05, 2020, 06:37:55 AM »

OK thank you for all your answers, it seems that this is a harder question than I first thought. Ideally what I wanted was an equivalent to a KP, basically just screw it into your model and charge up, seems that is not the case. Bill, does your Caproni use a rubber type construction or slightly more robust for power? I am guessing your rubber power Jungmann will be closer to what I looking for, how close to Eric,s original structure is it?
Logged
billdennis747
Palladium Member
********

Kudos: 60
Offline Offline

United Kingdom United Kingdom

Posts: 4,031



Ignore
« Reply #8 on: April 05, 2020, 07:34:35 AM »

OK thank you for all your answers, it seems that this is a harder question than I first thought. Ideally what I wanted was an equivalent to a KP, basically just screw it into your model and charge up, seems that is not the case. Bill, does your Caproni use a rubber type construction or slightly more robust for power? I am guessing your rubber power Jungmann will be closer to what I looking for, how close to Eric,s original structure is it?
You are right - electric FF scale would be more popular if there was an off-the shelf solution, but there isn't. However it does seem that there is a lot of leeway as far as power goes; just add more electricity. The system I used is very well-suited to the Caproni, which is 33" mean span and 200g - a converted rubber model.
My Jungmann is a 30" reduction of Eric's plan with rubber construction eg basswood tail outlines. I'm sure it would also suit the same electrics, as should my 32" Strutter
Bill

PS If you don't have the August or September Aeromodeller, I can send you the details of the system if you pm your email
PPS If you intend to enter any BMFA events, keep it under 200g or you will need to buy some radio control to turn it off
« Last Edit: April 05, 2020, 07:47:09 AM by billdennis747 » Logged
Jack Plane
Platinum Member
******

Kudos: 41
Offline Offline

United Kingdom United Kingdom

Posts: 1,784




Ignore
« Reply #9 on: April 05, 2020, 07:57:17 AM »

Mike

I don't have any experience of electric for outdoor free flight, but I've had good success with Atomic Workshop kit for indoor scale.  Its a learning-curve but not a steep one, and once you've done your first installation the rest are easy.

Their Voodoo motors  range from the V10 direct drive (10g thrust for very light models up to 20g) through the 15 geared (max 30g, used with a 130mAh LiPo on my 28g Peanut Bristol Scout both indoors and out), V25 geared (up to 50g AUW) and V45 twin geared (90g).  I don't know what kind of AUW a 0.5cc DC Dart would normally power (*) but the Voodoo 45 Twin with its 6" prop and fueled with a 220mAh LiPo should easily cope with a mid-sized outdoor model.

(* The last model I built for diesel outdoor FF was around 1976: Gordon Whitehead's 24" all-sheet Bristol Scout from the free plan in my original copy of Nov 1975's Aeromodeller, described as suitable for 0.3-0.5cc motors.)

The third component in the electric 'power-train' is the flight profiler.  Atomic's is called the Zombie and is a wizard piece of kit.  There are four tiny potentiometers:  the first pair control the first flight phase (power and duration) while the second pair the second phase, each phase can be up to 60 seconds.  Also, by setting the second phase power to zero, instead of there being a step-change in power after the first phase's timer ends, the second phase just gradually reduces in power from whatever it was in the first phase down to zero, over whatever length of time you've set the final pot to.

Charging LiPos is easy, and you don't need to use or adapt the sort of kit one would normally buy for electric RC.  I use a small 12v 3.2Ah lead-acid brick to power the tiny charger via croc-leads.

Atomic Workshop website here (run as a micro-business as a sideline by Jonathan Crossley, Richard's brother):  http://www.atomicworkshop.co.uk/catalog/

13" Bristol Scout video at 4:40 here (see also Richard's Consolidated flying boat powered by similar Atomic kit at 0:40): https://youtu.be/ZHOemtsah78?t=279

Currently building a 16" Pilatus Porter float-plane as part of the Walt Mooney Cook-Up, to be powered by the same Voodoo 15 as the Scout, see Reply #676 here:  https://www.hippocketaeronautics.com/hpa_forum/index.php?topic=25052.msg256266;topicseen#new

If you'd like any more help, then PM me your phone number and I'd happy chat you through things in more detail... got plenty of time at the moment !!

Jon
Attached files Thumbnail(s):
Re: Electric power for Scale Models
Logged
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!