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Dec 13, 2019, 06:47 AM
Lee
Lee
PERFECT LANDING !!!
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If I am gluing long spars in I will turn the heat up while I am gluing so the glue stays hot enough but I will turn it back down as soon as I am done with the spars.
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Dec 13, 2019, 04:15 PM
aka: Major Tom
I've got a few flights with my Reaper on 3S 3200 but today was a whole new level of flying for me ..... 4S 2800! Whoa what power. In case you can't tell, this was my first flight ever with a 4S battery. Everything is faster with loops, rolls, and overall speed. I had no idea there would be such a big difference in batteries. I also turned up the rates to give me better aerobatics so I'm still adjusting the rates a bit with each flight.

Bam! 4S
Dec 13, 2019, 05:29 PM
Lee
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the fastest way to go 100+ is a battery upgrade. Don't forget to change the prop size too.
Dec 13, 2019, 06:59 PM
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Quote:
the fastest way to go 100+ is a battery upgrade. Don't forget to change the prop size too.
Exactly, the master has spoken, the "C" rating is huge, for batteries under 4000mah, 65-130C really necessary, can drop a little if 4000mah and up (all 4s). Part of why I love the Castle Lite ESCs, can download in the air data, amazing the battery sag when pushing it, and the lower C batteries just don't perform adequately. Have posted many of the graphs in this thread. How warm/hot the battery is speaks volumes. eCalc is an invaluable program to see what the motor/prop combo will get you, including stall speed with higher pitch props.

Example: a 3000mah 65C should pull 195A, but now way in reality, and getting even close has huge voltage drop. I figure 1/2 of the value from the math, so that setup should max at 95-100A.

If using a 4S 2800, really need a high C rated battery, or get a visit from Puff the Magic Dragon. 2800mah @ 40C theoretically 102A but no way, with luck to get 60, and not for long, the puff away and into dud pile (mine is huge, learned the hard way). Would anticipate for speed may be upgrading ESCs. Castle Lite 75 or Plush 60/80 my minimum for high powered stuff, occasionally Castle 50 Plush 60 for small wings. My new full size Reaper has Castle Lite 100.

Welcome to the world of speed freaks!!
Last edited by Rdimand; Dec 13, 2019 at 07:12 PM.
Dec 13, 2019, 09:59 PM
aka: Major Tom
Quote:
Originally Posted by Lee
the fastest way to go 100+ is a battery upgrade. Don't forget to change the prop size too.

Rot Row! Didn't change the prop .... went with the 7x6. What should I have changed it too?
Dec 14, 2019, 01:06 AM
Lee
Lee
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You will need to go to a smaller prop. Use a amperage gauge to pick the prop. I am guessing a 6x4.
Dec 14, 2019, 02:29 AM
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Shurt: what motor?? can run some eCalc combos.
Dec 14, 2019, 10:06 AM
aka: Major Tom

AMP / WATT meter findings - WHOA!


This is the motor I've been using. I'm also using a Plush 40amp ESC. (I have a feeling you are going to say "buy the 60amp ESC) I bought a 50amp ESC from HK but that sucker is like a door-stop! It's very large. 4S with a 7X6 is a big mistake and I was lucky not to fry the ESC and motor pulling 48amps and over 700 watts!


Model No.: A3530-8
KV: 1700
Weight: 74g
Motor Dimensions: Ф35*30mm
Shaft Size: Ф4.0x49mm
Prop/ recom: 7x4/6x6
Battery: 2-4Li-Po
Idle Current: 1.6A
Load Current: 11.6A
Power(Watt): 460
ESC(A): 30A
Ri (Ω): 0.040
Pull (Approx): 440g


4S 2800 battery :
7X6 prop = it jumped to 48amps / over 700w before I quickly shut it down (clearly not the way to go)
6.5X4 prop = 34amps / 530w (to many watts for a 460w motor)

3S 3200 battery:
7X6 prop = 32amps / 373w

The 3S set up seems about perfect with the motor / ESC but I've got to figure out something else if I want to fly 4S.
Dec 14, 2019, 10:12 AM
pull up -- PULL UP!!!
Not necessarily. Have you checked to see if the motor is getting hot during those wattmeter tests? Many people over-drive their motors if it isn't getting hot. I run 600W on my 3530/1700kv 4S 7x6 without heat problems. But I only run sporadic full throttle, not the entire flight.
Dec 14, 2019, 12:51 PM
Lee
Lee
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The manufacturers recommendations are intentionally conservative so they don't get claims of motors not able to handle the amperage. I usually run the motors higher than the recommended amps and rarely have motor problems. I bench test the motors and see how hot they get before flying.
Dec 14, 2019, 07:36 PM
Registered User
Quote:
4S 2800 battery :
7X6 prop = it jumped to 48amps / over 700w before I quickly shut it down (clearly not the way to go)
That should be OK with adequate esc. But that seems small (3530) for a full size Reaper in search of anything close to 100mph. We use 3542's or if light, 3536's, Plush 60 ESC the minimum for faster setup. The math kills you, speed is proportional to power cubed. To double speed, need 2x2x2 power, or 8x power. To go up 50% in speed it's 1.5x1.5x1.5 = 3.4x power. Math sucks....

Here is the Castle logging on my Vertigo, much smaller than Reaper, with 3536-2200kv, just to show difference of higher C battery, way more power. It's very fast as small. Tattu 1800mah 4s 65C badass battery, but not for Reaper. Probably the minimum that I use in 2700 4S is Zippy 2700 4S 60C for low cost, have a 2 year old one still going strong. https://hobbyking.com/en_us/zippy-co...lipo-pack.html. There are better, but price goes up. Chinahobby has some great options, more like 3000mah.
Last edited by Rdimand; Dec 14, 2019 at 07:53 PM.
Dec 16, 2019, 07:29 AM
Lee
Lee
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It isn't just the amp rating on the motor you have to worry about. Your batteries won't last as long if you run them at max burst amp ratings and your speed control may let the secret smoke out. You have to set up a system that matches all of the components.
Dec 16, 2019, 11:52 AM
aka: Major Tom
Quote:
Originally Posted by Lee
You have to set up a system that matches all of the components.

The Reaper I have built is set up for the 3S 3200, with 40 amp ESC and 3530 motor. All three seem to work great together and fall within the guidelines on the watt/amp meter. This sucker flies like a dream and hard to believe I'm the one who built it! lol I just wanted to try 4S for the first time on something.

I'm guessing that I'll BUILD ANOTHER REAPER with 4S 2800 batteries! Or, is there another wing ... the Bandit?

Laying in bed last night thinking of what Santa will bring me, I had a thought of building a Bandit and using the Reaper components 40 amp ESC, 3530 motor and 3S 3200. The Bandit would be an awesome aerobatic wing with this set up. Plus, it would give me the opportunity to fly my Reaper with a 3536 motor, 60 - 80 amp ESC, and 4S 2800.

Thoughts?
Last edited by shurt; Dec 16, 2019 at 04:43 PM.
Dec 17, 2019, 07:34 AM
Lee
Lee
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The Bandit is 6 oz lighter just because of the narrow wing. I love the way it looks in the air. It is easier to balance with a smaller battery keeping it even lighter.

It is one of my more flown planes. This is a fairly big 57" wing. Not many 57" wings can do what this does on this small of a battery and motor.


Bandit 57 Symmetrical Wing - M (7 min 5 sec)
Dec 18, 2019, 05:57 PM
aka: Major Tom
Is the Bandit more aerobatic than the Reaper?


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