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Old 12-13-2012, 04:19 PM   #1
jedorme
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Default Venture 60 Electrified

Bruce Tharpe (who designed the original Sig 4 Star 40 & 120 while at Sig) is getting ready to release a batch of new kits for his Venture 60. I plan on getting one & converting it to EP. Is there anyone out there who has converted one of these before?

If so, I would welcome any suggestions on the best way to do it, particularly in building the Lipo hatch in the area where the fuel tank goes. I want to have a top hatch access without weakening that area of the fuse. Everything else should be fairly straight forward. Thanks,

Jed
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Old 12-14-2012, 04:45 PM   #2
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Hi Jed
Just heard about Bruce's re-release on some other little forum... Great model, I had a little hand in altering the design somewhat to use electric power - did the woodwork mostly, after eleven years with an electric Four Star 40. Bruce did sell some of the electrocuted V60 kit, with the mods and altered plan.

Battery hatch. The V60E pre-dated LiPos in sizes and capabilities for models like that, but much the same should apply. First off, suggest you build the wings, stabs and as much as the fuselage as you can, stop before you apply the forward top sheeting to the fuselage, put it all together with the expensive bits (radio gear!) in place and see how the balance is going - you can just lay the battery atop the fuselage. Make allowance for covering and any bits you can't fit, and you will have a good idea where the battery needs to go to maintain balance.

What we did on the V60E - and hundreds of Four Stars various - was to open up the top of the former at the wing LE so the battery could drop in the top with nothing in the way. Hope the attached shots show this clearly enough. The fuselage sides on mine were reinforced by a strip of 1/4 x 1/8" spruce glued to the side's inner top edges. Though it looked a little 'open', that model flew for 11 years, had the odd 'unusual arrival' and survived life at 5.5lb or so and 600W. The hatch went too far forwards, which I never got around to fixing.

Putting the battery where the fuel tank used to live is fine if (A) The model balances, and (B) All your batteries weigh the same. An ounce difference that far forwards, with no way of moving the pack to compensate, shifts the CG enough to make a difference.

The hatches on my 20 and 40 were made by cutting the top deck, then building the hatch to fit in the space and match the end profiles. Much easier on the 20, which has a constant section top hatch, not the tapered one of the 40.

The 4*40 is about the most popular kit 'electrocution' ever, and all of what folk have done to the Four Star series can be applied to the V60E. Not sure about the canard built around a wooden walking crutch and a Four Star 60 wing though, but it flew great all the same. You will have a superb sports aerobatic model, but if you fancy making life a little more exciting, many folk have done clip-wing versions of the Four Stars and V60 - one tip bay removed per side.

Good luck with your project

Dereck


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Name:	battery hatch.jpg
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ID:	164858 Four Star 20EP modified to top hatch
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ID:	164859 My original Four Star 40 top hatch
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ID:	164860 Original 4* had fuselage radio aft of the wing
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Old 12-15-2012, 05:16 AM   #3
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Hello Dereck - As they say about pictures being worth 1000's of words, I really appreciate the photos you provided, particularly the first one of what looks to be a very comparable design to the V60 (probably the Sig 4 Star to which you refer). I think that is exactly what I pictured in my mind's eye, & this photo coupled with your detailed description should make my life (& the hatch's likely outcome) much more certain than my trying to come up with something on my own. I really take your advice to try to build the entire model with the CG in mind, as I just finished a 3M glider where that was not done as much as it should, & I can't fly with the bigger Lipo I had in mind due to nose heaviness. I don't have the V60 or its plans yet, but photos of older ones show a fairly good extension of the nose from the cockpit/wing LE location to the firewall. So I'm hoping that this will give me some flexibility in locating the Lipo.

I spoke with Bruce at length about eliminating the outer bay on each wing panel to reduce it to about 66" instead of 72", as I both was originally looking more for a 40 size model & also wanted to fly it with my stores of 4 cell Lipos which I use on 3 or 4 models with 46 sized motors. And I'm a retired guy that just started flying 4 years ago so am not looking for 3D or unlimited verticals - I like flying on the wing & nice & easy maneuvers. But he convinced me that the wing loading would be better with the 72" wing & that my 800 watts of power with 96 ozs. of thrust with a 46 motor would work with the V60 just fine. It should weigh about 6 1/2 pounds all up if I build it right.

He also told me that with the newer lighter power systems, the things you & he did to create the electric version probably would not be necessary any more. So he doesn't plan to offer the EP version in the future. Right now I'm flying a Sig Sr. Kadet & Funster that I converted to EP using the same power systems with good results, so I am pretty sure he is right about using it on the V60.

I'm really looking forward to both the build & flying the V60, & anxiously await his release of the kits. Thanks again for all your good advice. Cheers,

Jed
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Old 12-16-2012, 07:09 AM   #4
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Hi Jed
You've made a good choice in the V60, it'll give you some great sports aerobatic flying. Balance is now the big issue, where it used to be weight when the equivalent of a 4s pack up around 4000mA weighed maybe 30 oz. Our motors are a lot lighter than their glow lump equivalents, which can play havoc with a CG. They're also shorter, which leads to issues of fitting them to glow firewalls, but reckon you know that already.

The funny part is that even though so many models are now being made for e-power from the off, they still often have a glow-ish placed firewall. Go figure! There's many complex, expensive and/or diddly ways of dealing with that shortness of motor, but the plywood discs that come in Sig's Four Star 20EP kit to mount behind a motor have an elegant simplicity to them.

One thing you need to do is have a good hatch security system. My Four Star 40 above preceded small rare earth magnets and had a mechanical latch, though it did eventually catch up with magnetic technology. The FS 20 uses a tab at the front that latches under the forward top decking and is full fuselage internal width. At the back is a 1/4" diameter magnet in the vertical formers of the hatch and fuselage top deck. Holler if that's not clear and I'll ship you a photo off my real computer.

When you get to building, as usual, address the hatch as soon as possible. It's much easier to make them fit nice when you can get at things than to diddle with a largely finished model.

Looking forwards to how your V60 project goes.

Dereck
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Old 12-17-2012, 07:01 AM   #5
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Hello Dereck - you're right about weight vs. balance these days. I calculated the weight of my 46 sized motor, ESC & 4S4400 Lipo compared to an OS 61 with a full 16 oz fuel tank, & the difference was about 8-10 ozs. And then that weight changes during flight as well. So glad I got into this hobby just when EP was coming into it's own & I didn't have an investment in glow power.

Not long after I soloed, my first real plane build was a Sig LT-25 kit I electrified, & I really appreciated the ply motor mount spacers that I got from another kit (a Sig Seniorita EP) to use for the Sig tail dragger. Wing mounting bolts & a battery hatch were far more of a problem than attaching the motor.

Your added description of the Four Star hatches also helps & I think I understand without troubling you for any other added photos. I did see a Four Star 40 build log on one of those other little sites , & I think I will add what I saw there to your suggestions. Basically I want to build a box frame around the hatch base, with an added center hatch brace, to allow it to drop into a fuse's outer box frame to provide some added rigidity to that area. Also think I will use RE magnets fore & aft to secure the hatch.

I will not only plan to keep you apprised of my V60 build progress, but might even occasionally beg for some needed help or advice when Bruce T is too busy making kits to do so. Who knows, if I don't completely bollux things up, I might even put some build reports online! Cheers,

Jed
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Old 12-17-2012, 06:44 PM   #6
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Originally Posted by jedorme View Post
Bruce Tharpe (who designed the original Sig 4 Star 40 & 120 while at Sig) is getting ready to release a batch of new kits for his Venture 60. I plan on getting one & converting it to EP. Is there anyone out there who has converted one of these before?

If so, I would welcome any suggestions on the best way to do it, particularly in building the Lipo hatch in the area where the fuel tank goes. I want to have a top hatch access without weakening that area of the fuse. Everything else should be fairly straight forward. Thanks,

Jed
Yeah, those larger electric conversions can work out very well. With quality electric motors/ESC/batteries, they can easily outperform the same model with glow power.

And they start everytime, regardless of temperature. Speaking of that, be absolutely certain to put in protection against accidentally starting that motor up front. When you get to these size power systems, that prop on the front can do real damage.

I've used a Spektrum DX7 with a programming mix to kill the throttle unless the gear switch is active. It's much easier to do with my Spektrum DX8.

Here are some conversions I've done:
Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222

Hacker 6S2P A123 powered Models
http://www.wattflyer.com/forums/showthread.php?t=44686

AEAJR's Site on Electric Power
http://www.wattflyer.com/forums/showthread.php?t=18521

BEC Linear Current Rating
http://www.wattflyer.com/forums/showthread.php?t=63497

DennyV
Retired and the days are just too short, busier than ever!
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Old 12-21-2012, 06:31 AM   #7
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Originally Posted by kyleservicetech View Post
I've used a Spektrum DX7 with a programming mix to kill the throttle unless the gear switch is active.
My Hitec Aurora9 radio has a throttle lock & I auto set it when the radio first gets turned on, & I don't turn it off until I'm out of the pits with my plane on the ground ready for take off.

Jed
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Old 12-21-2012, 11:02 PM   #8
Dereck
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HI Jed
Idle thought back on my Four Star 40 electrocution. When I did it, 600W+ electrics were still pretty rare and the motor was one of two brushless on the US market and the only one at the time that came with easily swapped gear ratios - the motors were inrunners and had to be geared - and an ESC that offered a true speed control from zero to flat out. It is still superior to anything I've had since, though that Tom Cimato, the guy behind MaxCim motors, had a little street cred in this region - some of his work in speed controlled electric motors was onboard the space shuttles.

Eventually, I did a lot of gear ratio/prop size testing on the 4*40, starting with props around 11", which is close to what the design was built around, but slimily impelled of course. Ended up with a very un-scientific decision that the best prop was a 15 x 10 doing 6800 RPM flat out with around 600W into it.

That decision was arrived at more by the ability to do a convincing knife-edged loop from level flight than any stream of long numbers and hard words

These models can manuevre extremely well, but a high top speed - forget it. The other good point was that the 4*40 also has a tendency to float on down the runway and refuse to come down the last couple of feet and stop flying. That 15" prop disc on very low revs threw a lot of drag into the equation and cured that tendency pretty much for good.

If you'd like a history lesson, the MaxCim website is still hanging out there - http://www.maxcim.com/ Worth a late night read, to make you appreciate brushless outrunners with modern ESCs all the more. Still wish we'd stuck with geared inrunners though. Much less fuss and if you bought slightly the wrong motor or wanted to use your motor with a different size of battery or prop, swapping a $5 gearbox pinion took about five minutes with two hex keys and a strip of office paper.

D
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