champion

well?

Jason W M

My Feedback: (6)

That depends on the gearing, prop and battery used...

One of the more typical set ups is using the Park 400 4200kv motor, 6.6:1 gearing and a 12x6 prop with 10C+ capable 3S 2100+ mAh packs. This set up pulls around 22-24 amps depending on the pack used, and 35-40 ounces of thrust.

The same gearing/prop/battery with the Park 400 3700kv motor will pull around 16-18 amps delivering around 30-32 ounces of thrust.

Jason Merkle
E-flite Product Manager
Horizon Hobby
http://www.horizonhobby.com

champion

Thanks!



one more question whats the difrence between thrust and static thrust ?



Thanks again!

boosted180

My Feedback: (8)

LVRCFlyer, does it really pull 22-24 amps? is this an actual figure you got from bench testing or an estimate?

in another discussion, someone else said that the himax 2025 4200 on same gearbox, prop only draws 13.5 amps, producing 35 oz of thrust. the eflite and himax are supposed to be the same motors......

i'm actually running the himax motor and it doesnt seem like it's drawing that much current. my speed controller can only handle 18 and battery only about 12-15.....

if you're correct, i'm worried b/c i dont want to burn out my speedcontrol or battery (kokam 1500 3s 8c discharge).

does anyone know how many amps and how much thrust from a himax 2025 4200 4.3:1 on a 11x4.7 prop?

thanx,
brian

TailTwister

My Feedback: (1)

I don't have a real number from testing on a bench, but I fly the Park 400. I have it geared at 5.33:1 with a 12x3.8 APC sf prop. It pulls my 24.75 ounce Mini Funtana with plenty of power. I metered it once with the 6.6:1 and a 12x6 APC at 18.6 amps. I'm guessing I'm a little above that with the current set up.

Static thrust is measured in a still position, like on a bench or with the plane restrained. This gives you acceleration and the ability to pull from a hover or such. Thrust, or dynamic thrust, is measured with the plane in motion as in flight. The numbers are often different, depending on the prop. Props behave differently as they "unload" in flight.

Generally speaking... Flat pitch wide diameter props create tons of static thrust, and the opposite creates more dynamic (flying) thrust. Turbines create huge amounts of thrust, but little of it is static thrust.

Does that make sense?

Jason W M

My Feedback: (6)

Brian -

My numbers are actual MEASURED outputs - not estimated values based on calc programs. Using Motocalc, it says we will only pull 13 amps, but that is not the case in "real world" experience with todays newest LiPos, ESCs, props, etc.

What we have found is that the APC E props will pull less current (around 15 amps with the same motor/gearbox/battery) than when using the SLO FLY style props. But because it pulls less current, it delivers less power and thrust too. Yes, the Himaxx/Park 400 motor might only pull 13-15 amps with the APC 12x6 E prop geared 6.6:1, but thrust is less than 30 ounces. The APC Slo Fly or E-flite props "grab" more air and will pull more current while producing more thrust.

The only way to know the actual power and performance of your set up is to measure it. Pick up an AstroFlight Whattmeter so you can check your particular set up. From the sounds of it, you are pushing your Kokam 1500s too hard - the Whattmeter will let you know for sure!

boosted180

My Feedback: (8)

thanx for all the info. i dont have a whattmeter so i dont know for sure. but the hobby store i bought my quietstorm and motor from said that he personally measured the himax 2025 4200 6.6:1 on an apc slowfly 12x6 prop and got 14 amps on the bench. he said that he personally guarantees me that it will not pull much more than that if it does and burns out my 18amp speed control he'll replace it free. he said that the motor itself is rated for and wont support more than 20amps anyway and that it would also burn out if i load it up with anything that pulls more than 20amps for any length of time.

anyway, this is my first brushless and i just wanted to make sure that i didnt burn out my 18amp speedcontrol or kokam battery packs. i just got some etec 1700 so they should be fine.

one last question: does anyone happen to know if 4.3:1 gearing with 11x4.7 prop puts out more thrust or a 6.6:1 on a 12x6 prop. and which draws more amps?

thanx,
brian

Jason W M

My Feedback: (6)

Brian -

If your store employee was using the Kokam 1500s for his testing, it is possible. Those cells can not handle much current beyond 12 amps and will drop significantly in voltage under such a load. Using high quality, 10-12C capable discharge cells, dozens of people here and on various forums are also reporting 22-24 amps at full throttle. We use the Thunder Power 2100 packs for all of our testing and have dozens and dozens of flights on our motors at bursts to just over 20 amps with no problems.

Your 18 amp ESC will not "burn out" as long as you are only using full throttle for short bursts. However, you will still likely pull less than 20 amps with those ETec 1700s. If you want max power from your motor, packs such as the Thunder Power 2100s or other brands of 10-12C capable discharge cells work best.

4.3:1 gearing and an 11x4.7 prop will pull more current and deliver less thrust than 6.6:1 and a 12x6 prop.

boosted180

My Feedback: (8)

thanx a lot for all the info, LVRCFlyer. i was kinda wondering why my power seemed to be a bit low compared to other people's who've posted on the forums, using the exact same motor, gearing, prop. i guess it was my kokams.....

the etec 1700's are supposed to handle 20 amps discharge. i think it's rated at 10-12c's.

the reason why i was avoiding the thunderpower 2100's is b/c i was afraid they'd weigh too much (compared to the kokam 1500's and etec 1700's).

anyway, i'll try the etecs first and see what happens. i gotta get my plane together first. i crashed and completely destroyed my first one b/c of a mechanical problem..... i was soooo disappointed! so i'm working on my second one now!

brian