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Old Jun 29, 2010, 10:53 AM
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United States, CA, San Clemente
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Originally Posted by 3D-Dabbler View Post
I have a Scorpion 4035-250 in another 70" plane spinning a 20x10 apc e. It pulls about 2100 watts at 70 amps on 8S. Tons of thrust. ~20 lbs.
I will actually be flying mine out of a medium sized park, about the size of a football field and need to keep the speed and sound down a bit. So, do you really think that the lower Kv motor and that set up is a good choice? What are the pros and cons? Also, will the cc ICE 80 HV support that kind of draw in bursts? Thanks for the help! I am a little new to the world of electric.
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Old Jun 29, 2010, 11:36 AM
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Richmond, VA
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Originally Posted by Efishensea View Post
I will actually be flying mine out of a medium sized park, about the size of a football field and need to keep the speed and sound down a bit. So, do you really think that the lower Kv motor and that set up is a good choice? What are the pros and cons? Also, will the cc ICE 80 HV support that kind of draw in bursts? Thanks for the help! I am a little new to the world of electric.

The CC ICE 80 HV is the perfect ESC for the 4035-250. 70 amps is below the 80 Amp limit of the ESC plus it gives the ability to up the voltage, if you like, to 9S or 10S. That would, in turn, lower the current draw even further. The max continuous amps for the motor are 65 amps. The ESC and the motor are close enough to their published limits that you could essentially run at full throttle for your entire battery pack. The motor has always come down VERY cool. The motor does not get stressed at all.

If keeping speed down is a concern for you there are 3 ways to solve for that:
1. Monitor your speed and throttle back if you are going too fast. Pitch speed with the 4035-250 on 8S and a 20x10 APC Thin Electric is only 56 MPH. So it does not go too fast.
2. Prop down - You can put a 20x8 prop on the motor and drop that to 48 MPH.
3. Get a different plane that has a lower wing loading and therefore lower stall speed.

At full throttle, the motor is spinning a 20x10 at only about 6400 RPM on 8S. So the noise isn't too bad. At half throttle the plane is very quite and not really noticeable. I hover my other plane at a little less than half throttle. The noise can be kept to a minimum by limiting how much you use full throttle. But in any case, my 57" electric planes and 48" electric planes can make just as much noise as my 70" planes.

If you want to lower noise further then you can use an XOAR or Turnigy Light Electic wooden prop instead. However, your overall thrust may decrease a bit as well.

A third way to decrease noise is to stay away from noisy maneuvers. A full throttle KE spin is a very noisy maneuver for instance. With an APC prop a KE Spin is about 3 times as noisy as with a wooden prop - prop flexing and the associated vibration shakes all of the covering on the airplane.

Your flying space is a separate issue. If it is literally 300' by 150' then you may have a challenge with this size plane. It is not the speed that is the issue but obstacles and the ability to have enough space for maneuvers.

I flew a 70" plane in my neighborhood once. My runway (the road) is about 300 feet long from the point where there is not a whole lot of traffic. (the road extends another 300 feet further but is too busy to land there. However, I make my landing approach over that area). Light posts trees etc etc all make a cross wind landing a potential challenge. There is very little space to bail out.

Additionally, with a 300' by 150' area there is no room for a KE Circle. Blenders, tumbles, KE Spins etc. would all be very tight as well. There is no room for any errors and it is probably a stressful experience with an expense plane on the line.

So, the net result for me at least, is I take my 70" planes to the club field where there is an 800' runway and 3/4 of mile of airspace is every direction.


EDIT: I forgot about cons of using this motor. The only con really is that you will have to go to higher voltage if you want to prop down to an 18" prop. An 18" prop will also be noisier (since you have to get the RPMs up to get the same thrust ... However that applies to any motor spinning an 18in prop) Additionally if you go to 9S or 10S you need a BEC. However, you already were looking at an CC ICE HV 80 and that requires a BEC anyway. If you don't want that con then limit yourself to a 20 inch prop and an ICE 100 on 8S. It will work just fine with analog servos. If you want digital then you need a BEC anyway.
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Last edited by 3D-Dabbler; Jun 29, 2010 at 11:50 AM. Reason: forgot cons
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Old Jun 29, 2010, 12:07 PM
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Thank you for the advice, My Landing Zone is limited to 100 yards+ but the Air-space is good. Going with the CC BEC Pro 20 and the HS-7985’s & HS-5245’s as well. I think I will pull the trigger on the 250kv motor running on Two 4-Cell 5000mah 25c packs. And use the larger Prop’s. She is still in the shipping box right now so, how is the ground clearance for a 20” Blade?

Thanks again!

Great Thread!

Paul…
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Old Jun 29, 2010, 12:12 PM
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United States, GA, Cumming
Joined Feb 2004
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20 inch blade is no problem.

Another motor that we have had great success with is the AXI 5320/18. I have run 6S, 7S and 8S set-ups and all work great. 20x8 on 6S 18x8 and 18x10 on 7S and 8S.
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Old Jun 29, 2010, 02:10 PM
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United States, CA, San Clemente
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I am going to order a Pair of 4000mah 5-Cell’s for the 5 min “Extreme Flight” Lol… If anyone see’s a problem with this Lower Kv Motor set-up, Please feel free to pick it a part… I am going to order the gear at week’s end.
Thanks!
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Old Jun 29, 2010, 02:26 PM
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Richmond, VA
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I only fly with 3700 mah and 4000 mah packs for 8S. I set my timer for 5.5 minutes. So when I hit the ground, I have been in the air for 5.5 to 6 minutes. The packs come down at 3.85 volts to 3.9 volts typically.

It adds 6 ounces to 8 ounces of weight depending on the packs you buy.

I do a lot of 3D and generally value floatiness over flight time. If you are similar you may not need the 5000 mah packs.
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Old Jun 29, 2010, 02:47 PM
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Originally Posted by 3D-Dabbler View Post
I only fly with 3700 mah and 4000 mah packs for 8S. I set my timer for 5.5 minutes. So when I hit the ground, I have been in the air for 5.5 to 6 minutes. The packs come down at 3.85 volts to 3.9 volts typically.

It adds 6 ounces to 8 ounces of weight depending on the packs you buy.

I do a lot of 3D and generally value floatiness over flight time. If you are similar you may not need the 5000 mah packs.
You’re absolutely right. So, my LiPo order should be Two or Three – Pairs of 4000mah 25c 4-Cell Lipo’s a One Pair of 3500mah 25c 5-Cell’s?

I am now the proud owner of two 208B Ichargers. Also, I am going to get a pair of Group 27 Marine Grade Deep Cycle Batteries and wire them in series for 24v for field charging. That should Cook a few Batt’s off at the Park?
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Old Jun 29, 2010, 02:57 PM
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I went a little crazy. I have 16 battery packs for 8 flights before recharging. My battery box is made up of Rhino 3700mAh 25C, Rhino 4000mAh 4S2P 25C ( I don't like these because of the shape) and Turnigy 4000mAh 20C packs.

So, I don't recharge at the field. It is usually tough for me to get through 8 flights in a row before I have to be somewhere else, the weather changes, the field gets too crowded etc.
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Old Jun 29, 2010, 03:13 PM
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Dabber, What Brand do you recommend then? It looks like the Turnigy from "China-King" seems to be the best bang for the buck. And you say the 25c is good to go?

Thanks once again for your help. This takes a big bite $$ out of the learning curve.

Paul.
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Old Jun 29, 2010, 03:26 PM
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Columbia SC
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Originally Posted by EXTREME FLIGHT View Post
20 inch blade is no problem.

Another motor that we have had great success with is the AXI 5320/18. I have run 6S, 7S and 8S set-ups and all work great. 20x8 on 6S 18x8 and 18x10 on 7S and 8S.
It looks like I am going to get a chance to try out that AXI motor this weekend, It will be interesting to get a comparison.

I can't wait for the weekend to get here so I can get some quality stick time on my 70" Extra!
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Old Jun 29, 2010, 03:28 PM
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Huntsville, AL.
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Originally Posted by hercdriver7777 View Post
I can't wait for the weekend to get here so I can get some quality stick time on my 70" Extra!
Don't forget to pack the cameraman!
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Old Jun 29, 2010, 03:36 PM
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Columbia SC
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Don't forget to pack the cameraman!
Well, camera man #1 is going out of town with his wife and kids (lame..). Camera man #2 shakes like a wet dog and makes weird noises in the mic when he holds the camera. Camera man #3 is a tripod with absolutely zero natural ability to follow a moving plane.

I will do my best to get some vid
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Old Jun 29, 2010, 03:51 PM
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Originally Posted by hercdriver7777 View Post
Well, camera man #1 is going out of town with his wife and kids (lame..). Camera man #2 shakes like a wet dog and makes weird noises in the mic when he holds the camera. Camera man #3 is a tripod with absolutely zero natural ability to follow a moving plane.

I will do my best to get some vid
Now thats funny. Looking forward to see you tame the 70" Chris.
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Old Jun 29, 2010, 07:11 PM
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Richmond, VA
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Originally Posted by Efishensea View Post
Dabber, What Brand do you recommend then? It looks like the Turnigy from "China-King" seems to be the best bang for the buck. And you say the 25c is good to go?

Thanks once again for your help. This takes a big bite $$ out of the learning curve.

Paul.
I have had really good quality from Zippy Flightmax, Turnigy and Rhino. I have about 30 batteries that are a mixture of all 3. I only seem to have one goofy turnigy battery that has one cell that is consistently .02 volts lower than the other cells. I guess my favorite is Rhino. But I buy which ever has the right form factor, price and C and is most importantly "IN STOCK" when I go to buy.
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Old Jun 29, 2010, 09:35 PM
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United States, FL, Palm Harbor
Joined Feb 2007
652 Posts
anybody flown this with a small gas engine like dle or syassa30?? looks awesome..
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