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-   -   Advise for coverting a GP Fokker DR.1 ARF (http://www.rcuniverse.com/forum/glow-electric-conversions-132/2325556-advise-coverting-gp-fokker-dr-1-arf.html)

westridge 11-07-2004 09:08 PM

Advise for coverting a GP Fokker DR.1 ARF
 
I am planning on ordering a Great Planes fokker DR.1 ARF. and covert it to electric, I would like to know if someone has already done this and or can offer me some advise. The power plant that i will be using is a
FUN500-27 Brushless Motor, Jazz 40-6-18 Speed control, 14 x 6" 13X6.5E wooden prop, (Brushless Set 5000 )

I would like to go LP for batt but I would like one that does not take hours to charge yet gives me atlest 20 mins of flight.

Thanks

Matt Kirsch 11-09-2004 02:49 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
You left out the most important piece of the equation, the battery. The battery, NOT the motor, is where the power comes from. It doesn't matter what motor you have up front, as long as it can handle the power from the battery. However, if you don't put enough battery in the plane, it won't matter how big the motor is or how big the prop is, it won't fly well.

Let's start at the beginning. We're mostly interested in the weight of the plane to figure out how much power it needs. So how much is the plane supposed to weigh according to the box?

As far as LiPolys go, 20 minute flights on a plane this large will be EX-PEN-SIVE. You can get the power, save some weight, and save some money too, as long as you're willing to live with 10 minute flights rather than 20.

LiPolys don't necessarily take "hours" to charge. That's just a result of poor planning. LiPolys can be charged at 1C, meaning a one-hour charge rate, meaning it really takes about 90 minutes for a complete charge of a drained pack. Normally we don't drain them right down, so it will usually take less than an hour to charge. Unfortunately, that's as fast as they can be charged, due to the fact that voltage can't exceed 4.2 Volts per cell. As long as you get a charger, or combination of chargers, that can handle the cell count and capacity at 1C, you can charge in about an hour.

westridge 11-10-2004 12:35 AM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
The plane is 9.1 lbs. I also dont mind putting out money for a good batt.

Greg Covey 11-11-2004 09:29 AM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
Westridge,

I feel that your FUN500 power system is not a good choice for converting the [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXAUC3&P=ML]GP Fokker Dr.1[/link] to electric power. The 9lb tri-plane will require more power to fly properly.

You will want a power system capable of delivering over 1000 watts and the Kontronic Brushless Sets do not currently offer this.

Matt Kirsch 11-11-2004 10:03 AM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
Unfortunately, you can't go by the physical size of the motor, or the diameter of the prop it spins as your only criteria. Your Fun 500 might turn a 14x6 prop, but it doesn't turn it at near the RPMs a .91 4-stroke would. A .91 4-stroke turns a 14x6 at nearly 10000 RPM. The Fun 500 probably only turns it at around 5000 RPM. At full throttle on the motor, you're only slightly above an idle on the .91 4-stroke. You go from 2-stroke to 4-stroke to spin a bigger prop at a lower RPM for better efficiency and less noise. With electric, you take it one step further. You want to spin an even BIGGER prop at an even LOWER RPM than a 4-stroke.

Just IGNORE the motor completely until the very end. Believe me, that is the best way to approach it. It's a tough thing for people with glow experience to get out of that, "it's bolted to the nose, therefore it's the source of the airplane's power," mentality. Get your Watts figured out first, then the Amps and cells, then figure out the motor.

Greg's right on with his estimate of 1000 Watts, IMHO. Triplanes have tremendous drag, and need to have plenty of power to overcome that drag. You also want to spin the largest prop you can to maximize thrust and efficiency. What's your prop clearance? You'll want at least an inch when the plane is "tail-up" on its takeoff roll.

1000 Watts in NiCd terms is 20 cells, 50 Amps. This translates directly into 6S for LiPoly, with as many P as necessary to handle the current and give you the duration you want. The P depends on the cells you choose.

So, you're looking for a motor that can handle 20 cells at 50 Amps. That's as easy as looking at a catalog. Remember, it doesn't matter which motor you get, because they can always be geared down if they don't spin the right size prop.

If a manufacturer offers several that fit the cells/Amps criteria, take a look at their weights, and how much weight you'll need to balance the plane. For the Dr.1, you'll need some extra nose weight, so look for a heavier motor.

Manufacturers that provide application tables with their motors make your choices easiest. For example, modelmotors.cz provides application tables for nearly all their AXi outrunner motors. It's as simple as looking up on a chart which motor is right for your plane. For an AXi, the 4130/16 is rated for 20-24 cells, and can handle peak currents of 50 Amps. The chart, and a little basic knowledge about propellers will allow you to pick the right prop to make the motor draw 50 Amps at full throttle.

Trinut 11-11-2004 04:02 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
This conversion was covered at www.ezonemag.com.
Great Planes aslo lists recommended gear for this electric conversion.

westridge 11-11-2004 06:41 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
The Motor combo I have mentioned is the motor that was recomended by Great Planes, check it out in thier we site. I also think that this plane is way to big for me, I have just seen some pics of it and it is way too big. I am currently working on My Model Tech P51 ARF and it is working out well, almost have all my goodies for it.

Greg Covey 11-12-2004 01:33 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
I understand that point. My point is who do you go to for advice on electric flight; Tower Hobbies or RCU? Buyer beware!

Greg Covey 11-12-2004 01:38 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
I understand that point...that's my point.

westridge 11-12-2004 02:32 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
Good to know you can on the Manufacture to steer you right

Matt Kirsch 11-12-2004 04:11 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
As my boss's boss's boss's boss (i.e. the CEO of the company) says, "Trust, but verify." I can't say whether or not a Fun500-27 will handle 900-1000 Watts or not. All I know is that you'll need around 100 Watts per pound to overcome the tremendous drag of three wings and the big round flat nose.

westridge 11-12-2004 09:45 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
Yes, but what if Mr Newbie does not know about RC forums and is trusting what he is told to buy to later find out it is not good, whould they return his purchase for a more suitable power plant ? No, but what in fact they should do is test whith what they are posting as the best choice. Let me plain simple it

"Items needed to convert this plane to electric
Motor ESC Power/Battery Aeronaut Prop APC Prop Drive Set
FUN500-27 (KONG2461) Jazz 40-6-18 (KONM3100) 38A at 14 cells (16.8V) 14 x 6" 13X6.5E (APCQ3065) Brushless Set 500 (KONG5040 "

That what is reads. It should read Items that may or may not work to convert this kit is "

Anyway I do really like this plane and would love to do the conversion but it is to big, I already have some nice kits and my wife would kill me if i tried to hang this one above the TV. (:

westridge 11-12-2004 09:47 PM

RE: Advise for coverting a GP Fokker DR.1 ARF
 
Please delete.


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