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Offline Suds  
#226 Posted : Monday, February 4, 2019 11:41:37 AM(UTC)
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Originally Posted by: Suds Go to Quoted Post
The finished electric GRU (gear reduction unit) is shipping to me and I should have installed onto a 105" AJ Laser shortly. Unfortunately the weather doesn't look good the next few weeks, but I'll get it airborne at the first opportunity possible. Going to test a variety of 12S setups: 2S 8000mah, 2S 10,000mah, 2S2P 11,600, and 2S2P 12,400. I'd guess the 8,000 or 10,000 be great for 3D flying but will need the ~12,000mah for IMAC.
GRU complete.jpg (1,630kb) downloaded 5 time(s).


Well the electric 105" AJ Laser is alive. I had fun putting 7 flights on it yesterday on a unseasonably warm Feb-3 day in Indianapolis. I know this was a 3D flight but think the unit will also translate well if not better for IMAC. I was getting around 5.5-6 minutes on the 8,000mah and 7 minutes on the 10,000mah packs. Guessing 12,000mah+ will be needed for two IMAC sequences.
Offline Steve Stanton  
#227 Posted : Monday, February 4, 2019 1:20:23 PM(UTC)
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It will be interesting to see what the all up weight is with the 12000 mha batteries and the flying time
it provides. That will be what really tells whether the gear reduction arrangement really provides any
advantage.
Offline Suds  
#228 Posted : Monday, February 4, 2019 1:28:33 PM(UTC)
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Originally Posted by: Steve Stanton Go to Quoted Post
It will be interesting to see what the all up weight is with the 12000 mha batteries and the flying time
it provides. That will be what really tells whether the gear reduction arrangement really provides any
advantage.

Yes, I still need to weight the plane with the power system installed w/o packs and then will be easy to calculate the total weight with variable pack sizes. Will also need to hook up the power meter to pull demand as well as measure motor temps to ensure everything stays in line.

Although anecdotal currently, I know a fellow pilot that has a 106" 3dhs Edge powered by a large Hacker and he ran 12S-12000 and managed less then 5 minutes (closer to 4) while I was able to achieve more flight time with smaller packs as noted above.
Offline rclad  
#229 Posted : Monday, February 4, 2019 2:04:27 PM(UTC)
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Great flying, Rob! The weather was fantastic yesterday for flying. I got lots of practice with my 95" flying Intermediate.

Can you post more details about the setup you flew with the GRU? Gear ratio, prop, motor Kv, and AUW with the various packs?

The numbers I'm getting from eCalc show that 10,000 mAh packs are sufficient for two Intermediate sequences on the 104" Extra with an AUW of 28 lbs. The load on the batteries is less flying IMAC vs 3D, if everything is setup to maximize thrust and flight time, not just thrust. In other words, it's doable, if you're willing to fly with a thrust to weight ratio of 1.6:1 instead of 2:1.
Greg Hladky
Flying on a wing and a purpose...
and physics, power, practice, preparation, plans...
and pioneers who pushed the envelope!
Offline Suds  
#230 Posted : Monday, February 4, 2019 2:16:49 PM(UTC)
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Originally Posted by: rclad Go to Quoted Post
Great flying, Rob! The weather was fantastic yesterday for flying. I got lots of practice with my 95" flying Intermediate.

Can you post more details about the setup you flew with the GRU? Gear ratio, prop, motor Kv, and AUW with the various packs?

Thanks Greg.
I will pull weight and power demand in time. I just finished up the plane yesterday early afternoon and didn't waste time to weigh it or put it on the power meter. Went to the field, added the packs and guessed on pack location for proper CG by holding the wing tube. Tested on the ground while holding the plane, after I was satisfied with the thrust and throttle response; I let 'er rip into the sky. Fortunately the CG was spot on to a touch nose heavy and the power system was well behaved. Should be fun this year.
Offline Suds  
#231 Posted : Friday, March 22, 2019 10:29:59 AM(UTC)
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Greg,
I had my motor rewound to a 515kv and I'm spinning the 28x12 PJN prop right around 6000-rpm +/- 100rpm from battery variances (18t pinion / 60t main gear). Currently running 12S-8000mah and managing 5-7 minute flights depending upon flying style. Will move up to 9,000mah for 3D flying and 12,400mah for IMAC flying.
Very happy with the performance the system delivered in Tennessee last weekend at a 'pop up' event where 40 pilots showed up.
I managed to get video of 3 different pilots flying the electrified 105" AJ Laser. None of them IMAC style flying although Alex Barron did perform a number of high speed snaps. Amazing flying by these three considering it was their one flight on the plane - not always easy considering everyone has different radio and plane setup preferences. I was happy that the electric setup felt pretty natural to these pilots that normally fly 120cc gas.
https://youtu.be/pb8kfsBMToE
https://youtu.be/aqOedXLKmeY
https://youtu.be/MfS2686RU8A
thanks 1 user thanked Suds for this useful post.
rclad on 3/22/2019(UTC)
Offline rclad  
#232 Posted : Friday, March 22, 2019 12:33:10 PM(UTC)
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Thanks, Rob. Impressive power! I can't wait to try the StinGR on the 104" Extra. I won't be getting mine until the end of April.
Greg Hladky
Flying on a wing and a purpose...
and physics, power, practice, preparation, plans...
and pioneers who pushed the envelope!
Offline rclad  
#233 Posted : Monday, September 16, 2019 10:50:46 AM(UTC)
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Now that the contest season is over here in North Central, I can finally get back to work on my electric 104" Extra. I was hoping to fly it this year in at least one contest before writing a follow up article on its performance for the newsletter. Once flying season arrived I wanted to fly, not get stuck in my basement building. And my 95" Extra managed to keep me competitive (but just barely) in Intermediate.

I ran into a problem with the new Savox 2790s I installed in the wings. They won't hold center with just a small amount of pressure (less than a pound) applied to the aileron trailing edge. I've got three of them - one per aileron and one for the rudder. This is very disappointing. So now I'm planning to replace them with Futaba HPS-700s. Talk about monster torque, these babies put out over 1000 oz-in!
Greg Hladky
Flying on a wing and a purpose...
and physics, power, practice, preparation, plans...
and pioneers who pushed the envelope!
Offline steve pennypacker  
#234 Posted : Tuesday, September 17, 2019 10:33:28 AM(UTC)
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Originally Posted by: rclad Go to Quoted Post
So now I'm planning to replace them with Futaba HPS-700s. Talk about monster torque, these babies put out over 1000 oz-in!


I'll be very interested to hear how the A700's do with centering and current draw.

Speaking of... anyone know where you can get good prices on Futaba 177's?
Offline Dangerous Dan  
#235 Posted : Tuesday, September 17, 2019 10:57:18 AM(UTC)
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Originally Posted by: steve pennypacker Go to Quoted Post
I'll be very interested to hear how the A700's do with centering and current draw.

Speaking of... anyone know where you can get good prices on Futaba 177's?


I know a couple who have used them on Carden’s and cam arrows with excellent results. I’m considering a single A700 on my carden pro rudder

2017 SC Sportsman Regional Champion
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The answer to all questions lies in the bottom of your fuel can, and in your plane setup
thanks 1 user thanked Dangerous Dan for this useful post.
rclad on 9/19/2019(UTC)
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