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Old Jun 06, 2011, 10:55 AM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
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Originally Posted by eajohnson View Post
+cf landing gear
.. and use smaller rx batts than recommended for gas; servos are not trying to stabilize control surfaces against engine-induced vibration. I use 6% per flight on twin 1600mAh 2S lipos; one could easily go a bit smaller yet e.g. two 1300mAh packs. I'm running hitec digitals all 'round. Flying electrics it's no big deal to recharge your rc battery every few flights. And, flying electric we're in there checking all the cells on the main packs anyway and it's no trouble to check all the cells on the rx packs before and after every flight so any unusual power consumption would be noticed right away. I don't think I've ever flown more than four flights without recharging so that extra capacity is just along for the ride.

I removed wood from the motor box too but the wood is so light it made no discernable difference. The main reason we need to do that is to ensure airflow back through the fuselage for cooling.
Plane already comes with full CF parts. I'm using dual 2200mah 2s on rx, I could cut those down. Either way I know I'm heavy, my biggest weight savings will come later as I fine tune my battery requirements.

Eric, how did the contest this weekend go? This was your first actual contest with your electric 260 right? Care to share a bit on the results, and everyone else's overall reaction to your plane as well.
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Old Jun 06, 2011, 11:24 AM
Team Hacker
Geoff Dryer's Avatar
Vancouver BC Canada
Joined Jul 2006
1,169 Posts
Quote:
Originally Posted by eajohnson View Post
+cf landing gear
.. and use smaller rx batts than recommended for gas; servos are not trying to stabilize control surfaces against engine-induced vibration. I use 6% per flight on twin 1600mAh 2S lipos; one could easily go a bit smaller yet e.g. two 1300mAh packs. I'm running hitec digitals all 'round. Flying electrics it's no big deal to recharge your rc battery every few flights. And, flying electric we're in there checking all the cells on the main packs anyway and it's no trouble to check all the cells on the rx packs before and after every flight so any unusual power consumption would be noticed right away. I don't think I've ever flown more than four flights without recharging so that extra capacity is just along for the ride.

I removed wood from the motor box too but the wood is so light it made no discernable difference. The main reason we need to do that is to ensure airflow back through the fuselage for cooling.
I forgot about the landing gear! The stock aluminum gear is really heavy. The trade off is that carbon gear will break.

I second what eajohnson said about receiver packs. I have two 2300 A123 packs and I use less than 100 mAh out of each pack per flight. Those packs weigh a total of 400g (14 oz)
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Old Jun 06, 2011, 11:50 AM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
878 Posts
I'm using 2s lipols, so they are already lighter than A123 packs. Dropping to 2x 1300mAh packs would weigh about 6oz vs the 9oz my packs weigh. So 3oz there. But if I can find enough little things to change it would add up. I'm also running a smartfly power expander sport which is 1.8oz and I'm planning to add a turbo regulator which will be another 2oz. I could forgo that whole setup and just use a battshare direct into my rx and save some weight.

Eric what lightweight wheels are you using? I think I remember you mentioning a set. Going with lighter wheels and titanium axles might shave off something there too. Starting adding up the ounces and soon enough I'll be half a pound or more lighter.

I'm also using a splitter for my batteries as apposed to wiring up a 3 way Y harness. So I might do that to get rid of the splitter and connectors.
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Old Jun 06, 2011, 12:01 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
954 Posts
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Originally Posted by super_nova View Post
Eric, how did the contest this weekend go? This was your first actual contest with your electric 260 right? Care to share a bit on the results, and everyone else's overall reaction to your plane as well.
Well, since you asked...

Yes, it was my first contest flying the big electric, and 2nd sportsman contest ever as last year I wasn't going much flying during the summer.

With the help of this plane I took 1st place in a field of 9 (scored 6000), and there's no question it impressed many people with its power and showed people that big electrics have arrived. The proof is in the pudding as they say and there can be no doubt that an electric IMAC plane is competitive with the gassers. I think it's fair to say that the plane was even an object of envy amongst a few of the people there.

I'm still not happy with my downline braking, it was really picking up a good head of steam on the way down. This was running the 26x15. For the last day I switched my throttle curve so that when I cut throttle it was set for a slow rotation of the prop (not engaging the ESC brake and not freewheeling) and I think this was a bit better. However in the end I think the 26x15 prop is just not ideal in spite of its incredible efficiency. In the heat of competition I used a touch more power than I do during practice when I'm calm and generally am better on throttle management, but I still had usually 36-37% left in the packs when I was done two sequences, vs 38-40% on a practice flight. There's room to take a hit on efficiency in trade for better downlines. I want to try a Mejzlik 27x12 thin prop next. I may have to try the 27x12 three blade sometime as well, though its cost puts me off a bit as I know that generally if I buy a prop it's 95% likely to not be quite right and end up going in to my already substantial collection of unused props.

I'm not feeling much love for or from any of the prop manufacturers here; I don't think electric IMAC competition is on their radar because if it was then they would have taken care of all the expense related to developing and testing efficient props for our application and we wouldn't have to spend $1000 each experimenting with props trying to find something that works.

But hey, screaming downlines or not it was still a winner last weekend. :-)

Eric


IMG_7804 by Kennethpark, on Flickr
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Old Jun 06, 2011, 01:38 PM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
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Congrats Eric, thats great to hear! Did you drop the Spinner and Wheel pants for weight, or for other reasons?

Very happy to hear how well you did, wish I could have been there! Hopefully, I'll get my plane going soon and throw another big electric into the mix to help push these things forward. If I end up picking up a big 3 blade, I'd be happy to let you test with it anytime we end up at the same competition. Assuming the Predator motor you run uses the same bolt pattern as the hacker A100 (DA 100 bolt pattern).
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Old Jun 06, 2011, 01:40 PM
Barefoot Birkinsomething
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United States, CA, Hayward
Joined Aug 2004
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Originally Posted by super_nova View Post
Congrats Eric, thats great to hear! Did you drop the Spinner and Wheel pants for weight, or for other reasons?

Very happy to hear how well you did, wish I could have been there! Hopefully, I'll get my plane going soon and throw another big electric into the mix to help push these things forward. If I end up picking up a big 3 blade, I'd be happy to let you test with it anytime we end up at the same competition. Assuming the Predator motor you run uses the same bolt pattern as the hacker A100 (DA 100 bolt pattern).
im hoping to find enough time to get in some imac contests with my electric 104" slick as soon as its done. no one near me flys electric anything in IMAC, so it will be a real eye opener!
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Old Jun 06, 2011, 01:50 PM
Team Hacker
Geoff Dryer's Avatar
Vancouver BC Canada
Joined Jul 2006
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Originally Posted by eajohnson View Post
Well, since you asked...

Yes, it was my first contest flying the big electric, and 2nd sportsman contest ever as last year I wasn't going much flying during the summer.

With the help of this plane I took 1st place in a field of 9 (scored 6000), and there's no question it impressed many people with its power and showed people that big electrics have arrived. The proof is in the pudding as they say and there can be no doubt that an electric IMAC plane is competitive with the gassers. I think it's fair to say that the plane was even an object of envy amongst a few of the people there.

I'm still not happy with my downline braking, it was really picking up a good head of steam on the way down. This was running the 26x15. For the last day I switched my throttle curve so that when I cut throttle it was set for a slow rotation of the prop (not engaging the ESC brake and not freewheeling) and I think this was a bit better. However in the end I think the 26x15 prop is just not ideal in spite of its incredible efficiency. In the heat of competition I used a touch more power than I do during practice when I'm calm and generally am better on throttle management, but I still had usually 36-37% left in the packs when I was done two sequences, vs 38-40% on a practice flight. There's room to take a hit on efficiency in trade for better downlines. I want to try a Mejzlik 27x12 thin prop next. I may have to try the 27x12 three blade sometime as well, though its cost puts me off a bit as I know that generally if I buy a prop it's 95% likely to not be quite right and end up going in to my already substantial collection of unused props.

I'm not feeling much love for or from any of the prop manufacturers here; I don't think electric IMAC competition is on their radar because if it was then they would have taken care of all the expense related to developing and testing efficient props for our application and we wouldn't have to spend $1000 each experimenting with props trying to find something that works.

But hey, screaming downlines or not it was still a winner last weekend. :-)

Eric
Welcome to the Electric Hangar 9 Extra IMAC for Sportsman Club! (it is a very small group). Super job on winning in you first go with this plane.

I am the only electric pilot in the North West IMAC Division. I think that most of the other pilots just eye me suspiciously as they all seem to like their gas motors. I think that electric models would gain favor in IMAC if they enforced a box size. I think that part of the reason for the move to electric in pattern was because it helped in keeping to the box.
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Old Jun 06, 2011, 02:12 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
954 Posts
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Originally Posted by super_nova View Post
Congrats Eric, thats great to hear! Did you drop the Spinner and Wheel pants for weight, or for other reasons?

Very happy to hear how well you did, wish I could have been there! Hopefully, I'll get my plane going soon and throw another big electric into the mix to help push these things forward. If I end up picking up a big 3 blade, I'd be happy to let you test with it anytime we end up at the same competition. Assuming the Predator motor you run uses the same bolt pattern as the hacker A100 (DA 100 bolt pattern).
The spinner isn't on mainly because I'm still experimenting with props. As long as I'm running too fast on the downlines I don't want to add it (couldn't help!). It flies fine with no spinner. The predator does use the same bolt pattern (DA100).
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Old Jun 06, 2011, 02:16 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
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Originally Posted by rcbirk21 View Post
im hoping to find enough time to get in some imac contests with my electric 104" slick as soon as its done. no one near me flys electric anything in IMAC, so it will be a real eye opener!
I look forward to hearing how that goes. I think this is just the thin edge of the wedge wrt big electrics in IMAC. We have some Unlimited pilots in Quebec that are putting one together as well (Isabel Deslauriers and Ray Buyukgurel).
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Old Jun 06, 2011, 02:27 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
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Originally Posted by Geoff Dryer View Post
Welcome to the Electric Hangar 9 Extra IMAC for Sportsman Club! (it is a very small group). Super job on winning in you first go with this plane.

I am the only electric pilot in the North West IMAC Division. I think that most of the other pilots just eye me suspiciously as they all seem to like their gas motors. I think that electric models would gain favor in IMAC if they enforced a box size. I think that part of the reason for the move to electric in pattern was because it helped in keeping to the box.
Thanks Geoff!

That's an interesting comment wrt the box size. I didn't find that I flew appreciably differently from the gas guys in that respect, and actually because I had more power on tap than the gas guys, there were times when I deliberately flew bigger where I felt there was an advantage to doing so. A lot of people do love the sound of a gas motor, which I can appreciate because I have feelings for my 100cc Honda generator too.

BTW, I noticed that Hangar 9 kinda sabotaged their new 35% Extra 300 wrt electric conversion, by putting a massive hole in the bottom of the cowl rather than leaving it for people to cut out if required for them. To do an electric conversion you'd need to make a cover for that - what a pain! Makes me wonder if there are additional gotchas inside wrt place to be batteries etc. Again another sign of manufacturers just not having electric power on their radar.

Good thing the 35% Extra 260 is such a good plane on electric!
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Old Jun 06, 2011, 02:29 PM
Barefoot Birkinsomething
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United States, CA, Hayward
Joined Aug 2004
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Originally Posted by eajohnson View Post
I look forward to hearing how that goes. I think this is just the thin edge of the wedge wrt big electrics in IMAC. We have some Unlimited pilots in Quebec that are putting one together as well (Isabel Deslauriers and Ray Buyukgurel).
thats awesome! the guys in ohio are too stubborn to even consider it...
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Old Jun 06, 2011, 02:49 PM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
878 Posts
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Originally Posted by eajohnson View Post
I look forward to hearing how that goes. I think this is just the thin edge of the wedge wrt big electrics in IMAC. We have some Unlimited pilots in Quebec that are putting one together as well (Isabel Deslauriers and Ray Buyukgurel).
Are you helping Ray and Isabel with that setup Eric? Is there a build thread anywhere with details? Curious to see what they do, are they going to try a 40% setup or stick with a 35%er?
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Old Jun 06, 2011, 03:36 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
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Originally Posted by super_nova View Post
Are you helping Ray and Isabel with that setup Eric? Is there a build thread anywhere with details? Curious to see what they do, are they going to try a 40% setup or stick with a 35%er?
Yes, me and Phil Stang, another local electric pilot, are advising them as best we're able. They are starting with a 35% Aeroworks Extra as this is an airframe they already have one of and is therefore convenient for parts etc. They will be using the Plettenberg setup like I have. I'd like to see a 40% electric compete in IMAC as well, and I'd do one myself but I have no means to transport it!
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Old Jun 06, 2011, 03:59 PM
Jason
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United States, SC, Rock Hill
Joined Jun 2004
878 Posts
So are they going to mimic your setup? I wonder if there's enough capacity on board for a unlimited sequence x2. Your setup definitely sounds like one of the best so far in terms of getting the flight time you need without going overboard on weight. I'm also curious how well the Predator would run on 12S 10,000mah. It would pull more amps, but would it still be enough capacity based on what you're using on 14s? Worst case you could always go 11,600mAh like Geoff is doing. Something I'm leaning towards in the future, depending on how my testing with the Hacker setup goes. Ideally, I want to get to a 4 battery setup. Wish hobby king sold 7S packs...

I noticed Phil was flying the EF 78". What happened to the 88" Extra he had last year on Electric?

Sorry to hijack your thread Geoff, but I figured you don't mind the electric IMAC focus
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Old Jun 06, 2011, 04:35 PM
The Eh Team
Ottawa, Ontario, Canada
Joined Aug 2000
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Originally Posted by super_nova View Post
So are they going to mimic your setup? I wonder if there's enough capacity on board for a unlimited sequence x2. Your setup definitely sounds like one of the best so far in terms of getting the flight time you need without going overboard on weight.
Short answer, yes, their setup will be like mine. I believe there's enough for two unlimited sequences. I'm also going to try 5300mAh 30C packs from GensAce and see whether there really is an extra 300mAh -- the packs weight about the same as 5000mAh packs. If there really is an extra 300mAh per pack that's 6% more capacity for roughly the same weight.

Quote:
I'm also curious how well the Predator would run on 12S 10,000mah. It would pull more amps, but would it still be enough capacity based on what you're using on 14s? Worst case you could always go 11,600mAh like Geoff is doing. Something I'm leaning towards in the future, depending on how my testing with the Hacker setup goes. Ideally, I want to get to a 4 battery setup. Wish hobby king sold 7S packs...
Can't say, but I do concur that it would be convenient to run sets of four packs -- four 7S packs would be ideal. I'm sure the plane would fly on 12S. Of course, I want it to fly with more authority than a gasser, not just as good as but better was always my goal hence going with more volts.

Quote:
I noticed Phil was flying the EF 78". What happened to the 88" Extra he had last year on Electric?
I'm a little foggy on what happened with Phil's 88", I do know he had a rough year last year with some crashes. Also I believe it was underpowered, it may have been running on 10S/10Ah instead of 12S/10Ah (this is just off the top of my head so may not be correct ) .
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