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geo8498@mac.com
08-02-2005, 12:23 AM
i've been thining of changing my 4star 40 over to electric. i saw some the listing recommended at hobby lobby for it. not sure if i really want to invest the money in it, but i've been thinking it'd a nice plane to convert. anyone have any thoughts?

Mike Parsons
08-02-2005, 12:42 AM
I member of my club converted his 4*40 to electric. If I recall, he used an AXI 2826. I will see if he can post here what he used. It is a good flying plane.

-Mike

pcphill
08-02-2005, 02:18 AM
That would be me...

I flew my 4* 40 for years with an OS .52 four stroke before the conversion. It now sports an AXI 2826/10 spinning an 11x7 APC prop, Phoenix 45 ESC, and a 3S4P Kokam 1500 lipo. I could have used 3P, the setup only pulls about 30A, but I went for extended flight times.

The power is comparable to the OS .52. You could use a 4S pack and fly it faster than glow, but you'd need to add either an UBEC or RX battery.

Gotta go to work, pics and mods tomorrow.

ragbag
08-03-2005, 11:17 AM
Hobby Lobby has the 4*40 conversion setup ready to be ordered.

Look at this site: http://www.hobby-lobby.com/g2e-sig4star40.htm

They have several conversions listed, we are working on the Kadet LT 25 now. We are useing the AXI 2826-10. Will be starting a thread soon.
George
Gainesville Fl

buzzbomber
08-05-2005, 05:25 PM
pcphill, maybe you can post your modifications when you get a chance? I bought an AXI 2826/10 with the intention of converting a glow plane, and the four star is one of the candidates, so I'd like to see what changes I might need to think about.

pcphill
08-05-2005, 10:47 PM
Sorry, killer schedule this week....

I'll post pictures and comments this WE

geo8498@mac.com
08-06-2005, 02:12 PM
Does anyone know if that setup from Hobby Lobby would work well with a 3300 sub-c NIMH pack of maybe 7 or 8 cells? Not sure if I could invest the money in 2 of those $120 Lipo packs right away.

Mike Parsons
08-06-2005, 02:19 PM
You would want to go with 10 cells. But yes, it will work fine. The only thing that will suffer is flight time. Figure 8-10 minutes depending on throttle usage.

-Mike

Watts up
08-07-2005, 05:54 PM
for that setup you only need one pack.....as far as i am aware. Thats what it says on the HL website http://www.hobby-lobby.com/g2e-sig4star40.htm is this true

Matt Kirsch
08-07-2005, 07:53 PM
HL's website appears to be down, but if it's the pack I'm thinking it was (Kokam 3200mAh), then it'll easily handle the Amps. Kokam 3200 cells are rated for 20C, or currents 20 times the capacity of the pack. 3200mAh times 20C is 64 Amps, way more than the motor and ESC can handle.

geo8498@mac.com
08-07-2005, 09:59 PM
The number of 10 NIMH cells, seems like a fair comparison to the 3 cell Lipo, since we're talking 11.1 volts on lipo and 12 volts NIMH. Granted the equation isn't a true alternative, considering the other factors between the two types. But it makes sense. However, I'm not sure if that would be the same as comparing either to a .25 engine, since Hobby Lobby is recommending the 11.1V with the matching motor. Respectfully.

pcphill
08-08-2005, 12:25 AM
I'll avoid the gas/glow argument going on, except to note my conversion is pulling as well as my OS .52 4stroke on 3 Lipos. Efficiency probably accounts for some of the comparisons seeming skewed.

Back to Business...

Draw a line on your fuselage side 2 inches forward of the glow firewall. If you do this accurately you'll maintain the built in down and right thrust. Mesure the opening and cut a new firewall from at least 1/4 ply. Draw a line across the firewall 1/2" from the top and another 3/4" from the bottom. Draw a line from the opposite corners of the two lines to form an X on the firewall. Center your radial mount on the X, orientation optional and mark you mounting holes and the center hole to clear the motor axle. Drill cooling holes away from the mount.

Cut out the old firewall. A hobby saw is probably easiest. Epoxy in the new firewall along the previously drawn lines and use some triangle stock to reinforce it.

The cliff notes version for the rest:

Cut off the top balsa sheeting in front of the canopy and fabricate a battery hatch. This was the most annoying part of the conversion for me. Add a battery tray to the fuselage. I mounted the ESC beneath it.

Open one of the covered lightening holes aft of the wing to allow airflow through the battery compartment. My motor/ESC/batteries barely get warm.

I'm running out of steam...
If you have any specific problems I'll try to help.

pcphill
08-08-2005, 12:27 AM
Here is my battery, made up of 4 Kokam 3S 1500s paralled with an FMA circuit board....

pcphill
08-08-2005, 12:33 AM
pcphill, maybe you can post your modifications when you get a chance? I bought an AXI 2826/10 with the intention of converting a glow plane, and the four star is one of the candidates, so I'd like to see what changes I might need to think about.


Are you going to buid it or buy the ARF. The changes would be much easier if you're building it. I've heard that one guy who built one specifically for e power managed to shave 2 pounds off by adding lightening holes and substituting balsa for ply in some areas. It's really overbuilt for electric. OTOH, It'll take a lot of abuse as is:D

Cryhavoc
08-08-2005, 02:46 AM
You would want to go with 10 cells. But yes, it will work fine. The only thing that will suffer is flight time. Figure 8-10 minutes depending on throttle usage.

-Mike

Be advised that there are newer 3800mah Ni-MH cells out now. One report I read said that they actually charge up to 4200+mah when new. Besides the weight they would be a nice alternative for those still not wanting to make the switch to Li-pos.

Mike

buzzbomber
08-08-2005, 03:33 AM
Are you going to buid it or buy the ARF. The changes would be much easier if you're building it. I've heard that one guy who built one specifically for e power managed to shave 2 pounds off by adding lightening holes and substituting balsa for ply in some areas. It's really overbuilt for electric. OTOH, It'll take a lot of abuse as is:D
I was actually considering the ARF for two reasons: One, I've had at least one kit on the building boards continuously for the past two years so I'm a little burned-out and I'm looking for something quick-n-dirty, and two, I was hoping to get it in the air before the "flying season" ends for the year. Maybe I'll just relax, plan it out and buy the kit to build when the weather gets cold--we'll see.

pcphill
08-08-2005, 01:04 PM
Don't let me scare you off, the ARF would be fine. It could be done easier than I did it too.

Instead of moving the firewall, you could use the radial mount and use 2 1/2" screws and a 2" section of PVC to make a cheap,quick, and dirty motor mount. (details can be found on the EZone) I can't remember which company, but someone makes an aluminum mount that works the same way with 3 aluminum posts you cut to length.

Cut the hatch on the bottom, where it's flat, and it would be a lot easier. I just wanted it on the top.

You could to the whole e conversion in a single afternoon. It also would help that you haven't started with a 4 year old, multiple patch, fuel soaked dinosaur.

Matt Kirsch
08-08-2005, 05:07 PM
To all:

The so-called "glow/electric argument" has been removed. Sorry for stepping on any toes.

TKG
08-09-2005, 06:34 AM
Bruce Thorpe who designed the 4*40, has his own company now BTE.
He "redesigned" the 4* series and has the Venture 60 kits.
Several times in the past when he makes a run of Ventures he will make a smaller run of the E-Venture 60.
Just in case you have time for a bit larger kit.
Also a lot of 4* are getting their wings clipped one bay and for the more adventuresome try lowering the stab about 1/2" for improved knife edges.

Unbalanced prop
08-09-2005, 02:43 PM
Bruce Thorpe who designed the 4*40, has his own company now BTE.
He "redesigned" the 4* series and has the Venture 60 kits.
Several times in the past when he makes a run of Ventures he will make a smaller run of the E-Venture 60.


What is the :redesigned" 4 *? Is there a link or website or pics or something? Sounds like something I may be interested in.

Doug

Jollyroger
08-10-2005, 06:33 PM
Don't let me scare you off, the ARF would be fine. It could be done easier than I did it too.

Instead of moving the firewall, you could use the radial mount and use 2 1/2" screws and a 2" section of PVC to make a cheap,quick, and dirty motor mount. (details can be found on the EZone) I can't remember which company, but someone makes an aluminum mount that works the same way with 3 aluminum posts you cut to length.

Cut the hatch on the bottom, where it's flat, and it would be a lot easier. I just wanted it on the top.

You could to the whole e conversion in a single afternoon. It also would help that you haven't started with a 4 year old, multiple patch, fuel soaked dinosaur.

The mount you are thinking of is available from Esprit Models. I am using one on my conversion of a Goldberg Tiger 2. I had to add 1/2 " spacers to the mount, but it works very well and looks great I might add.
cheers jollyroger

pcphill
08-10-2005, 07:32 PM
That was it! I knew it was an eflite/glider site and I couldn't track it down.

As to previous posts....

Removing a wing bay would improve the sink rate for sure. I can't tell you how many landings I've aborted because it floats all the way down the runway. I've taken to flying it into the runway instead, although I have an extra wing I'll get around to cutting down one day.

Moving the elevator (and enlarging the rudder) would definely help the knife edge. OTOH this is a sport airplane, not an aerobat. Get all the different couplings built out of it and you'll end up with an Extra, so why not start with one. 4*'s are built for nice relaxed flying.

Tweet
08-11-2005, 03:03 AM
Airplanes only quit flying when they are ready to quit. If you are floating excessively with any airplane your approach speed is probably too high. Airplanes with light wing loadings can approach pretty slow. I had a Four Star 60 (glow) and with extra airspeed it would float forever. However, if I managed my speed on approach I could put it on a spot the same as any other airplane.

TKG
08-11-2005, 04:27 AM
What is the :redesigned" 4 *? Is there a link or website or pics or something? Sounds like something I may be interested in.

Doug

www.btemodels.com

Unbalanced prop
08-11-2005, 01:10 PM
Thanks a lot TKG! :D

Doug

pcphill
08-11-2005, 05:33 PM
Trust me, I've tried to slow it down. It just get into ground effect or something and breathing on the stick pops it up. Getting too close to stall on the final turn to slow much more.

Tweet
08-11-2005, 09:58 PM
Ground effect is real and more pronounced on low wing airplanes since it is a function of wingspan and proximity of the wing to the ground.

On models and full scale you have one airspeed before the turn and another slower airspeed for short final and over the numbers, that way you don't have to worry about stalling on the turn.

You might add a little more expo on your elevator low rates for landing if it is that sensitive.

I'm not saying floating isn't real or is easy to deal with, but there is an airspeed and approach that will let you land it where you want to.

AintQytRite
08-26-2005, 03:48 PM
To mee that motor that Hobby Lobby is suggesting is too small, 350 watts on a 5 pound plane? has anybody put a more powerful setup on a 4 star .40? what would be the better choice for verticle performance, a hacker B5013s on 4 lipo cells or an axi 4120-18 on 4 lipos?

Jollyroger
08-26-2005, 08:17 PM
I ran some motors through Ecalc and found the 4120/14 on a 6S Lipo would provide 160W/Lb. @43 amps w/ a13X8 prop.The 2826/12 would also be a good choice.Would be much better than the 4120/18 which would require more batts to provide the power. Believe me I know, I tried to convert a GP .40 Cub to electric with that motor and it wouldn't produce enough power to reasonably lift the plane off. Stick with the lower wind and you'll have plenty of power. Besides the Axi is a good bargain.
This is a project I have been thinking about for a while now.
A lot of flyers are building the wing with one less bay in each wing.Makes for a more maneuvorable plane with less tendency to float past you and on down the field.
I had a 4*60 with an MDS .68 on it. It was a real burner.
Good luck with your project. John Z.

AintQytRite
08-26-2005, 08:35 PM
reason i was askin is because i already have a hacker B5013S and a Nib axi 4120-18 and i already have 2 4s2p lipos and 2 3s2p lipos, maybe i could go axi 4120 with the 2 3s2p hooked up into a 6s2p fashion

pcphill
08-26-2005, 10:44 PM
I'm only pulling about 300W on mine, and the performance is almost identical to the OS .52 four stroke. Neither of them have unlimited vertical....
My AUW is about 4lb10oz, but I could have shaved a couple ounces on the battery.

If you're going to go with more motor/more prop, figure custom Gear in too. A 12" prop will be clipping the grass!

AintQytRite
08-28-2005, 05:52 AM
Im thinking 900 watts with a hacker with an 18" prop



I'm only pulling about 300W on mine, and the performance is almost identical to the OS .52 four stroke. Neither of them have unlimited vertical....
My AUW is about 4lb10oz, but I could have shaved a couple ounces on the battery.

If you're going to go with more motor/more prop, figure custom Gear in too. A 12" prop will be clipping the grass!

pcphill
08-28-2005, 08:15 PM
Im thinking 900 watts with a hacker with an 18" prop It'll definitely have awesome vertical, but that kind of power is wasted on a four star .40... That would do justice to .60 size. And if you go 18" the gear you'll need'll have you sitting at 45 degrees plus on the ground:eek:

Small mislabeled video of my Four Star last weekend.
http://whodafigured.com/drones/pcphil082105.wmv

Jollyroger
08-29-2005, 05:59 PM
It'll definitely have awesome vertical, but that kind of power is wasted on a four star .40... That would do justice to .60 size. And if you go 18" the gear you'll need'll have you sitting at 45 degrees plus on the ground:eek:

Small mislabeled video of my Four Star last weekend.
http://whodafigured.com/drones/pcphil082105.wmv

I agree. You can get by with a smaller power setup. Actually something in the 500 watts range would be plenty. I would substitute the plywood with balsa ie: formers and fuse sides. That would go a long way in weight reduction, and if you have an unplanned landing, you have the original patterns to use. Cheers John Z.

Unbalanced prop
08-29-2005, 06:22 PM
I agree. You can get by with a smaller power setup. Actually something in the 500 watts range would be plenty. I would substitute the plywood with balsa ie: formers and fuse sides. That would go a long way in weight reduction, and if you have an unplanned landing, you have the original patterns to use. Cheers John Z.

Also...........since I do so much repair work:rolleyes: I have found it is easier to repair balsa then plywood, as long as you pick up all the pieces.;) Balsa breaks cleanly and can be pieced back together, where plywood splinters and is harder to glue back together IMHO. I have a Four * in the box that I plan on making all balsa and cutting a bay off the wing. Gonna try and get it down in the 3 1/2 to 4 pound range.

Doug

michaelkramer11
11-08-2007, 12:09 AM
pcphill,
hey man, ive got a couple of questions about your 4*... i really want to convert one to electric, and was wondering first off if the arf would be a decent choice...with the same axi 2826/10, 11x7 APC prop, two great planes 11.1v 3200mah's in parallel, and the great planes 45 amp esc w/ bec..... i really tried to get pretty close to what you had. also, what kind of flight time do you get off of your setup? are the motor, electric, or esc hot when you bring her down??? and when you said "the setup only pulls about 30A" in your post on the thread, were you referring to the 3p or the 4p pack? thanks a lot for your help man, i'm just really interested into getting one of these converted over to electric pretty quick.

Neko
11-08-2007, 01:21 AM
I was going to go 4*40 and even ordered the ARF from Sig. Then after a week or so of it not arriving I called and they said they are back-ordered until December. So I went to my LHS and bought a Pulse XT 40 instead. Not flying yet, but check the threads here. It is said to be a sweet plane, and much like the 40 in behavior. Same setup more or less, too.

Unbalanced prop
11-08-2007, 01:58 AM
Man I forgot all about this thread. I never did post pics of my 4*. Ended up with a hacker A30 10XL and an APC 13 X 8 prop. Very stable smooth flyer with very good power. I made a couple mods, half the dihaderal, half inch larger control surfaces (rudder, elevator & ailerons) and two aileron servos. My AUW with 3S2P 4200 pack is 47 ozs.

Doug

Dereck
11-09-2007, 12:44 AM
Hi Doug
Maybe a little short of the full span 4* that flew on 8 x 500AR cells a couple of years back - plus a little added lightness - but yours has to be one of the lighter ones.

Mine started nearly years ago now, with 20 x SCRC1700mA Nicads into a MaxCim brushless, built box stock for a kit review / conversion article for a realworld mag. Its last drivetrain was 16 x 3300 NiMh into a Hacker B50/13S / 6.7:1 reduction - 600W into a 15 x 10 prop. By then it had the full range of modifications - clipped wing, larger ailerons, 25% larger tailplane on the fuselage bottom, lots, lots more rudder. Add in all I did to fit the initial huge battery, re-arrange the radio bay to accomodate it and take out a bunch of Liteply, and the only thing left 'original' was the wing section.

Working on it ...

The aerodynamic mods were worked out by Gary Wright - of E3D fame - and a bunch of his clubmates during a season long "One Design" competition series. The electric flight mods, I did after looking at a lot of other Four Stars - I'm happy to claim them!

Looking at the Pulse XT, I do see some evidence of China's national sport - reverse engineering ;-)

Am surprised at your half dihedral. Mine has the stock dihedral angle and, with the lowered, larger stab, can knife edge all day with little rudder or pitch interactions.

Right now, it's hanging off the shop ceiling, minus much of the fuselage covering and with a big wing warp. I spend far too much time swithering between either re-furbishing the old gal, as she's such a great sports aerobatic ride, or building what I idly called "Five Star 16" - which is a snappier name than Five Star 6S A123" ::o but suggests how long since I started the plans... In the interests of continuity, my design uses a Four Star 40 cockpit, as I handily have a spare, and its kinda cute in the right setting.

One day we should start the Four Star Owners Club. Open to any of the 40, 60 & 120 variants - BARFBuyers are in too, as well as the kits and conversions. We really should also canvas the BTE EV60 lot ( I did the conversion drawings for Bruce, BTW) as it really is close to a Four Star 60 Mk2. How's about the odd one-off Four Star 20 electrocutions though?

But definitely not the Doc Matthews Bingo low wingers ;-)

Regards

Dereck