WIZARD - a "Wonderful Wizard"

I have nearly successfully re-powered an RC plane with electric...but crashed into a post on takeoff run due to a non-steerable nose wheel. It is rebuilt and ready to try again, except I think I'll leave the nose faring for after a successful flight. I just need some good weather.

Add on soldering up my neighbor's twin engine transport, and seeing how he did the engine installs, and having a electric RC plane that I have crashed frequently, and rebuilt a near equal number of times (still not flyable, soon crashes = rebuilds though)

I've looked at a couple electric motors for these things.

The mounting can also go to the front with a ring mount at the nose, with the motor shaft more-or-less reversed. This is supposed to support the engine better for aggressive stunt.

Phil

Cribbs74 wrote:Ian,

I am not surprised the plane balances with the Bee engine. I think you will be OK with the electric setup.

It just depends on what you want to accomplish. If you wish to be re-aquainted with CL then even a heavy plane will fly level laps. If you enjoy it then build another.

It's a shame that you are restricted to electric as I feel that plane would be a real stunter if a TD was used to power it.

Who knows that little electric motor may surprise you!!!

Ron

Ron - see below - a single level lap without falling over isn't much to ask of it. I can time the run from a choice of 10 to 100 seconds (10 second intervals) or 1 to 10 minutes (i minute intervals). (Battery limit will be 4 minutes)

I finished fitting the motor today and trying the best way to route the wires - it would be a lot easier in a built up fuselage. Here is the motor, ESC and timer.



The timer, E-ZEE Control line timer, is simple to set up and use and without boring everyone with my test results -

I found the best set up was with a 3S 1300mah battery and the 7x5 propeller. After various testing, again to make sure that the whole shebang doesn't go up in smoke, I found that I would get 4 minutes out of that battery with a safe margin.

With the current set up - the 7x5 will spin 9,750 revs and the plane will have an all up weight of 342g (12 ounces).

I didn't want to wait for Roddie to complete his torque meter so I resorted to my tried and tested "pullometer".

Place your fingers around the fuselage (easy with this model) just behind the wing. Fire it up (just press the button!). Point it skywards - well, towards the ceiling as it is cold, wet and windy outside today. Steady the wing with the other hand.

Then, slowly release (but not completely!) your grip around the fuselage. If the plane climbs skywards under its own weight from stationery - it will fly!.

The tailplane will assist in stopping it. I must film this one day. Anyway, the Wizard passed and wanted to lift away.

(Roddie - if I had "fish scales", I would just hook them to the fin (  ) and measure the pull)

Now for assistance please.

Here are my questions : -

What line length would you recommend - 1/2 A seems to be 42ft but would this be suitable for the experienced inexperienced. Many, many years since I flew control line - much older, poor eyesight ....... Only ever flew one control line profile model and this was with an 049, smashed it and wrecked the engine! - all my successes were with much bigger, stronger and generally with .15+ diesels. (Not that I think I could handle that now!).

Balance - the battery is the weight monger (102g, 3.6oz) and I can position it for perfect balance. I do not want to perch it above or below the wing and am considering hacking the wing and fuselage to hold and bury most of it.



Now this leads me to a wondering - where the battery is position the C of G is met for a nose to tail balance. But what about wing balance?

Should a control line balance symmetrically like an RC plane with both wing equal? Should one wing be heavier than the other? A 3.6 oz battery is going to throw this out!

If one wing is to be heavier than the other - which one and by how much?

Line length anywhere from 35-42'

I don't know what length to suggest as I have no idea about electric and pulling power. Basically I would try 42' and cut back if you feel the line tension is not where it should be. If it were me I would start at 35' and add length if the plane can handle it. Seeing as it's been a awhile for you then it may be best to start at 42'

1/4 oz is usually the standard tip weight in the outboard wing on 1/2A. The wing will not balance as the outboard wing should be heavier to compensate for line weight. Holding the fuse at the nose and tail the outboard wing should slowly fall.

That is a huge battery!!! Is there any way you can use a smaller one? If not then if possible have it straddle the CG so it will have less effect and as close to the fuse as possible without it affecting the bellcrank movement.

I am surprised Rusty hasn't commented yet. He must be busy.

I am afraid the battery is non-negotiable - for 4 minutes the motor and prop needs the 3s(11.1 volt) 1300mah. I tried 2S (7.4v) much lighter with a variety of propellers. Does not pass the Ian pull test.

Everything is a compromise and I am quite willing to place the battery midships. Just wish I'd thought of it while building. Doh!

I'll second Ron's comment on line length, start on the short side, you'll still have a plane to use longer lines on.

There is a big difference in performance between 11.1v vs. 7.4, but do you need 1300mah for your 4 min flight time?

Turnigy 800mAh 3S 40C Lipo Pack
SKU: T800.3S.40 $10.88 WEIGHT : 122g | IN STOCK

The outboard wingtip should have some weight so as to counteract the weight of the control lines.  I believe the plans indicate a weight, and the amount.  The battery sitting on the wing can count towards this weight.  The tip weight is more important for stunt anyways, if you are going in circles for 60 seconds at a shot it won't matter nearly as much.  You can open the wingtip and add or remove weight later if necessary, if trimming requires, as your skills grow.  Tip weight trim most needed for inverted performance to be equal to upright performance.

Set the fore and aft CG using the battery and put it down with some velcro, as velcro seems to be the standard method.  (I actually haven't done a CL e-power ship yet) A backup rubber band or something  is not a bad idea too.

42 ft lines is good.  35 is what I have usually used with bees, as lower power engines pull around the shorter lines better, longer is nice when the power is available.  Remember you can go to a flatter prop to slow lap time as long as it flies fast enough to remain stable.

I am surprised you cannot get away with a much smaller 3s battery too.

Phil

pkrankow wrote:http://www.ecalc.ch/motorcalc.htm?ecalc&lang=en

I have Ecalc, PCalc, Scorpion and Motocalc. They are good guides to put you on the right track but they don't cover all motors.

I use these to get me in the right ball park but then use a watt meter to measure the current. A slight propeller change can be disastrous. After a one minute run, I apply a battery checker.

When I get the chance (tis New Years Eve - Happy New Year everyone) I will go into more detail with my checking process.

Thank guys - I will make my lines 35 footers.

Good Luck Ian! I thought the same thing about your battery choice.. but I do realize it's a balancing act. It might be worth trying a lighter weight/smaller battery, and alternate props before you do any cutting into the fuse though.

Happy New Year!
Roddie

Hi guys. Sorry I haven't thrown in any ideas, just haven't gotten much screen time lately with extra people in the house and on the computer. I hope I can get around to posting my own flight report from yesterday. Ian, I like your Wizard and it looks like it should be a stable trainer if not even surprisingly more capable than that. Sounds like your weight and wing loading is fine. I am curious, are the rib gussets in the plan or did you add that for extra bracing?

Like the others said, tip weight is mostly to counter balance the line weight. But with electric, you may need less weight than the standard 7g, because the torque of the engine is(usually) turning in the other direction and will help roll the outboard wing down. As was stated, that's the least of your problems for flying flat. But instruct someone on the edge of the circle to watch as the plane approaches and passes as low and level as you can fly it, to follow the lines as a reference and see if the wing continues along that same straight line, or if the outboard is tip-high or tip-low.

As far as lines, I use 40' on some very fast planes, so starting with 35' should be safe for 30 or 60 second test flights. I think velcro for the battery is a good idea for tweaking the C/G. It all looks well thought out and I'm looking forward to your maiden report.

Mark Boesen wrote:I'll second Ron's comment on line length, start on the short side, you'll still have a plane to use longer lines on.

There is a big difference in performance between 11.1v vs. 7.4, but do you need 1300mah for your 4 min flight time?

Turnigy 800mAh 3S 40C Lipo Pack  
SKU: T800.3S.40  $10.88   WEIGHT : 122g | IN STOCK

Thanks for this info Mark - I had to have a second look as 122g for an 800mah seems a little heavy. The 1300mh that I have are 102g.

Strange, me thinks. Then I realised that is the figure HobbyKing uses as the "packing" weight. The 800mah actually weighs 90g.

1300mah - 102g, 800mah - 90g would make a 12g (0.4 ounce saving).

These are my battery measurments with the 1300mah after one minute progressive runs with the 7x5 prop at 9,750 revs.

% remaining

Start 95
1 minute 76
2 minute 58
3 minute 38
4 minute 14

I don't think I would go for the 5th minute!

I had a bit of a disaster with the Wizard.

I was videoing the "Ian Test" and the motor came loose,  whipped around and around, came off and bust the propeller. All over in a few seconds.

I reconnected everything - and replaced the propeller (an APC clone 7 x 5) with an EMP 7 x 5. I didn't riun it through the watt meter and ......... the motor went up in smoke!

Two propellers, both 7 x 5, whopping difference on power draw!

Anyway, you live and learn but be warned!

I have replaced the motor and here are the "Ian Tests".

El cheapo 7x4



APC 7x4E



APC 7x5E



The first and the third video - the pull is marginal, although the planes weight is being held by the motor - you will notice that although my grip is not tight - it does really want to pull up.

The second video - you will see me release grip and let the plane climb against my hands. I am only steadying it.

I do the same thing when doing a thrust test.

I have a question though, why a 7" prop? Can you go down to 5-6"? I wouldn't pitch it over 3 as it may be too fast. On 35' I have to stay at a 2 pitch to keep it manageable.

I know nothing of electric, I am assuming that the motor you have selected is more powerful than a TD? Is that why you chose the 7"?

Anyway, the plane looks great and when you are up for it will be an excellent stunter. Good show Ian!

Ron

Cribbs74 wrote:

I have a question though, why a 7" prop? Can you go down to 5-6"? I wouldn't pitch it over 3 as it may be too fast. On 35' I have to stay at a 2 pitch to keep it manageable.

I know nothing of electric, I am assuming that the motor you have selected is more powerful than a TD? Is that why you chose the 7"?

Ron--

There are probably folks here with more electric experience that I have, but I fly a lot of electrics and all my heli's are electric.

Electric motor efficiency is tied to matching prop size with KV ratings and current levels.  The motor windings (AWG size and turns per pole) will set the RPM based on the battery voltage.  I run an 8x4 on that same motor.  Generally, running a smaller prop requires a higher KV rating.  On a 3s battery, loaded, he's probably looking at around 14 to 15K rpm.  You can run these motors up to their maximum rated speed, but only for a limited time to avoid overheating the motor, ESC or battery.  Generally, except for hotliners, you're better off running a lower KV to conserve battery capacity and couple that with larger prop diameters that we would normally run in 1/2A.

A TD is rated around 80 watts @ 22K.  I've seen this particular motor rated at 99W, but I think a more realistic figure is 80 to 85W.  The ESC will allow fine tuning the RPM to best match the plane, so using a larger prop will give better "hauling" power without having to ramp up the speed.

A perfect answer.

If I were running this on a 2s battery it would have an 8x4 propeller but this is an 049 model that was originally designed for, as Ron has indicated, a 5" propeller. For ground clearance my only option is to drop the size of the propeller and increase the voltage. Everything is trial and error. By error - burning out motors through carelessness.

Interestingly, there are very few motors advertised as being equivalent to 049. One the OS :-

OSMG9505
OMA-3805-1200 (.05 Size)
Rotor Diameter (mm): 38
Magnet Length (mm): 10
kV: 1200
Watts: 250
Weight (oz/g): 2.7 (76)

seems to defy all common sense!

Look at the specs:- (It is the first one)

http://www.osengines.com/motors/motors/motor-specifications.pdf

Recommended propeller is 9x6 to 11x7 ???????????????? Anyway, I bought one to test.

Thanks for the explanation. That is a whole lot to chew on. Way more effort than I would be willing to expend. I admire your ability to work this through.

Ron

Edit: How is John Goddard able to fly nitro engines in London?

John is a member of the Enfield Model Flying Club. They have three sites and they are NE London. I am in SW London.

http://enfieldmodelflyingclub.com/ourfields.htm

Although they are only 20 Miles away, they are on the other side of London and even these sites have restrictions.

20 miles trying to get to the other side of London is probably, at a minimum. one and a half hours drive (unless you travel at night!). A three hour return journey as opposed to a 5 minute walk!

Unless I take a detour - longer journey - it also takes me through the congestion charge zone. That is a £10 charge.

http://enfieldmodelflyingclub.com/members.htm

You may recognise John from the photo!

Used to be able to fly IC control line in Richmond Park (30 years ago) and then it was banned. That was only 15 minutes walk to the site!

That explains it Ian I won't bother you about it again   

I just want to see you get in the air is all. From an outsider looking in it's frustrating to see you have to reinvent the wheel when it would be so simple to bolt up a Cox engine and fly. It's not like you lack engines   

I understand you have limitations though. If you are ever passing through OKC give me a shout and we can fly in my backyard or just about anywhere there is room. Just bring some British sweets for the wife and you are golden!

Hope to see you flying soon pal!

Ron

Edit: John Goddard has an uncanny resemblance to Brad Pitt.