Great Planes Big Stick 60 to Electric - RC Groups
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Mar 27, 2009, 07:00 AM
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Gwalch's Avatar
Yippee!

Great Planes Big Stick 60 to Electric


I have finished converting a Great Planes Big Stick .60 to electric.

And since I did a lot a research on these forums I have decided to share the gained knowledge with everyone in case they want to do something similar.

It's not going to be a build thread as such.. as it is already finished.. but merely a repository for information.

The intention is to use this plane as a Tug for smaller gliders.

http://www.greatplanes.com/airplanes/gpma1220.html
Big Stik 60 ARF
Stock Number: GPMA1221
Wingspan: 66.5 in (1690 mm)
Wing Area: 1000 inē (64.5 dmē)
Weight: 6.5 lb (2.95 kg)
Wing Loading: 15 oz/ftē (46 g/dmē)
Fuselage Length: 59 in (1500 mm)
Engine Required: 2-stroke .60-.91 cu in (10-15 cc) or 4-stroke .91-1.20 (15-20 cc)
Radio Required: 4-5 channel w/5 standard servos

I have purchased a Scorpion S4020-16 motor
http://www.scorpionsystem.com/catalo...s40/S-4020-16/
which is the equivalent of a .60 glow motor.

For a staggering amount of information and support in relation to these fantastic motors.. have a look at:
FAQ - Scorpion Motors: Questions and Answers....
https://www.rcgroups.com/forums/showthread.php?t=660918
The people on this particular thread are more than helpful. (as are the majority of people on these forums)

I also have the Hyperion 80A Opto ESC
http://aircraft-world.com/shopexd.asp?id=5199
(I know I know.. it's Hyperion but it's what I had sitting spare)

The motor and ESC are mounted on a motor mount for Hyperion Z40 Series motors, or any other motor/gearbox with 25mm mounting pattern and M4 screws.
http://aircraft-world.com/shopexd.asp?id=3663

As for batteries.. I am using 2 x 3S packs joined in Series to make a 6S pack.
This is mainly because I have a heap of 3S packs lying around and also the ESC will only take up to 6S and I cannot justify buying another ESC whilst I have one that works perfectly well.

So far I have tried two props.
The 14x7E prop and the 13x8E.

The 14x7 prop gives me roughly 8-10 minutes flight time full throttle and going generally silly with manoeuvres, and has heaps of thrust.
Where as the 13x8 prop gives me a heap more speed but naturally sacrifices flight duration for speed.

I have been using the Scorpion Calc software to work out all my figures and it is rather good.
http://www.innov8tivedesigns.com/pro...roducts_id=507

I will get some figures together and post the results here at a later date.

Have attached some pics.

That's enuff for now... it's bed time.

Gwalch
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Mar 30, 2009, 12:16 AM
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Gwalch's Avatar
As I said in the previous post I have been using the Scorpion Calc software to work out all my figures.
http://www.innov8tivedesigns.com/pr...products_id=507

I have attached a couple of shots of the program running using my variables.
Eg: 14x7 and 13x8 props.

The figures shown on Scorpion Calc are pretty much spot on for the figures gained when using an E-Meter.

Hopefully this week we will try this plane out as a tug.


The tail has been fitted with an anti foul line, which is just a price of heavy duty fishing wire fed through and tied off.


As for the tow release, I picked up one of the Graupner Aero-Tow Cable Sets.

I have placed the plastic head part on the back of the fuselage at the trailing edge of the wing. See attached pics.

We glued this in place with epoxy and then put some carbon fibre around it in an attempt to make it stronger.

The only modification we have done is not use the tow release cable and sheath. Instead we just mounted a Hitec HS81 servo directly underneath the plastic head. Mainly because we had so much room in the servo tray and we figured go a direct pull down instead of pulling a cable on the angle.

The tow release works perfectly on the ground and we have put a fair bit of pressure on it in testing.


All we have to do now it try it all out in action.

Hopefully in a couple of days (weather permitting).
Apr 07, 2009, 11:20 PM
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Gwalch's Avatar
Well.. it works as a tug.
We took it out the other day and did 6 tows of a mates CMPro Ventus. 2.6M wingspan.
No worries at all.

Once we worked out what we were supposed to do it was nice and simple.
Plenty of power.

Batteries were 2 x 3S 2200mAh pack wired in series to make 6S pack.

Did 5 tows on the first pack.. then on recharging they only took 1700mAh
so pretty happy with that.

The tow line was bright yellow bricklayers string. 30M long with a breaking link of fishing line at the end.

Towed glider up.. released... did a low pass overhead to release the tow line and then landed.

All nice and simple really.

YAY!!


1st Aerotow (0 min 19 sec)
Last edited by Gwalch; Oct 22, 2011 at 08:13 PM.
Apr 09, 2009, 10:57 PM
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Gwalch's Avatar
Some more towing done today and a couple more photos.

There was a nice 10kt or so,. head wind and the sun was shining beautifully on our backs as we were playing.

We tried a different way of towing.. and that was to take off and then just climb on about a 45 degree angle. Plenty of height nice and quick.

The tug really needs a larger prop or else go to 8S batteries as when the wind picked up it struggled a little. But we still managed to get plenty of height and the glider pilot was getting up to 10 minutes worth of flying out of 1 tow.

Will try a couple of larger 15" props and see how we go with that.
Apr 11, 2009, 04:52 PM
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panzerd18's Avatar
Very very nice. Its great you're getting around 10 minutes from 2200mah.

Instead of going to an 8S I would definitely try a 15x6 prop or even get a 16" and see how many amps it is pulling. Your calc shows on 25 amps, you have heaps of headroom to run a bigger prop. You will probably run out of prop clearance before you reach the motors limit/ESC limit.
Apr 12, 2009, 05:17 AM
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Gwalch's Avatar
Quote:
Originally Posted by panzerd18
Very very nice. Its great you're getting around 10 minutes from 2200mah.

Instead of going to an 8S I would definitely try a 15x6 prop or even get a 16" and see how many amps it is pulling. Your calc shows on 25 amps, you have heaps of headroom to run a bigger prop. You will probably run out of prop clearance before you reach the motors limit/ESC limit.
Curse the Easter break in which all the shops close ... how dare they!!!
How am I supposed to buy new toys to play with!??

Roll on Tuesday, I shall go and get me some new props to try out.
Apr 24, 2009, 06:27 PM
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Gwalch's Avatar
Oh my word!!!

We have tried the 15" props and all I can say is.. WOW

After checking the Scorpion Calc software.. we decided to give the 15x10 a go.

Naturally we have had to sacrifice flight duration for performance.. but I tell ya what... who cares!!!!!

Short take off.. the glider was up in the space of 2 meters.. and then we just climbed out on about a 45-50 degree angle until it was hard to see the planes.. released.. and then the tug landed.

All in the space of about 70 seconds.

In that time we got to the roughly the same height we were getting out of a 3 minute tow with a couple of turns thrown in.

Absolutely amazing the difference.

Ended up only doing 3 tows out of 1 pack.. and used about 1600mAh out of the 2200mAh pack.

After a few more packs.. the glider pilot decided that the fence, rather than the ground, was a nicer place to land the glider.

So.. that of course meant that I just simply HAD to use the rest of the packs in a little bit of fun.

For a bigger plane.. which is quite simple in design.. damn that thing is fun when you crank it up.

Batteries exhausted.. pilot grinning like an idiot we called it a day.

These Scorpion motors are brilliant.
Do yourself a favour and try one out.
Apr 25, 2009, 01:48 AM
Xtreme Nut
I got the 40 sized one and she will go EP too. Been always dying to own a stick but never got around to doing it. Now, I only need to purchase the nose gear bracket.
Apr 25, 2009, 09:43 PM
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Gwalch's Avatar
Quote:
Originally Posted by tIANcI
I got the 40 sized one and she will go EP too. Been always dying to own a stick but never got around to doing it. Now, I only need to purchase the nose gear bracket.
Go for it.. you will not regret it at all.. they are so nice to fly.
Apr 26, 2009, 04:32 AM
Xtreme Nut
I am sure they fly fine, these are the planes that paved the way to 3D. I love how they look ever since the 80's but somehow never got to buying one. Will go look for the nose gear bracket first at the LHS. I can prob use the WM mount, that lines up with my motor radial mounts. Shall put my conversion up here.

I think my set up will be as follows:

Motor - Plettenberg Orbit 25/18 or AXI 4120/18
ESC - Turnigy 60A
Batt - 5S 4,900 mAh
Prop - 13x6E

I wanted to build a hatch like what you did but I realised that on the 40 sized plane, there is a bulk head between the firewall and the main former where the wing LE rests. Does your Big Stick have that?

No more covering coming off and oily mess on the plane!
Last edited by tIANcI; Apr 26, 2009 at 04:59 AM.
Apr 26, 2009, 07:03 AM
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Gwalch's Avatar
I just cut the top skin to make the hatch.. and the bracket you can see in the photo had a shaped section to conform with the fuel tank.. so I just removed the arched bit, left the rest.. and the batteries just slide in there nice and neat.

It is so nice just being able to land.. remove that hatch.. batteries out.. batteries in.. and away you go.

I used to hate the constant cleaning after glow fuel, then the filling of the tank.. glow drivers.. dodgy glow plugs.. tuning the motor... ewww

I ccould never go back to glow motors now.
Apr 26, 2009, 08:56 AM
Xtreme Nut
Aaaaaahhh ... its the same. So you cut it all out and then made a new hatch since that former is glued to the top portion. I don't mind removing the wing to replace my batt but I need to build a nice batt platform and be able to securely strap the batt down. Access to the ESC is also an issue.

I am thinking, 14" prop! Then we can talk unlimited vertical ... pull huge loops all day. Heheheheehe ...

I am all EP but of late I went back to GP for racing planes. EP will not cut it, it lacks duration. I bought a nice Jett Q500, a TT46 and a Rossi 53, so I can safely race against the GP guys without fear for killing my batt and also have the duration. I am enjoying flying my Great Planes Viper 500.
May 02, 2009, 04:53 AM
Registered User
Quote:
Originally Posted by Gwalch
After a few more packs.. the glider pilot decided that the fence, rather than the ground, was a nicer place to land the glider.

In my defence the tug pilot had a dodgy battery pack on board and we had to abort take of with very limited height. I was doing well at recovery until a pesky wire fence loomed up larger than life.
Thankfully not too much damage
May 27, 2009, 11:57 PM
Xtreme Nut
I finally started on my Big Stick 40 conversion. The build was easy but I was so lazy that its taken a whole week to do a few things. I got the motor installed with ease once I realised that I can just hack off the motor mount. The DuBro nose wheel brackets were too large.

I had to change the blind nuts to 3mm ones and that was an easy job. Here are some pics of her. The motor is a Plettenberg Orbit 25/18. Will be using a Turnigy 60A ESC and fly her on Rhino 5S 4,900s. I think a 12x10 or 13x8 should be just about nice.

Will maiden her this weekend.
May 28, 2009, 12:56 AM
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Gwalch's Avatar
Top Work!!
Will be interesting to see how the finished product turns out.

Keep posting your updates.


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