RacerStar AirA 2508 1200Kv motor review: an excellent choice for 6 or 7 inch quads

Introduction
​The Racerstar AirA 2508 motor is a brushless quadcopter motor sold under the racerstar brand but made by T-motor. This motor has a broad stator and tall height matched with a relatively low kV making it an ideal option for 6 or 7 inch quadcopters running 5-6s.

Up until recently there were few large stator motors available, typically the largest we saw on long range 7 inch rigs were 2208 (MB Primo). In fact for this reason I chose 2306 when I built my long range rig here. Although light, the disadvantage with the relatively small stator given the large and heavy propeller it needed to spin was poor control over the prop and a tapering off of power in the high throttle range along with a large increase in current draw (with no output benefit). This resulted in the quad feeling sluggish which I thought was just the accepted norm for a 7 inch quad.

Now there are a lot more larger stator motors around with wids of 24mm right up to 28mm and heights of between 6 and 8mm that are much better suited to 6 and 7 inch propellers. I chose to try the Racerstar AirA motors on my 7 inch build because they have a great price to quality ratio.

Build Quality
The "Air" sub brand from t-motor usually signalled a lighter weight price competitive motor and it is the same here. Retail on this is $20 each or $70 for 4 although they've been as low as $12 on sale. For this you get excellent t-motor build quality that cannot be compared to regular racerstar motors but not the titanium shaft, single strand windings or super strong 7075 aluminium bell of the much more expensive motors. I don't find these especially important though and many tend to agree which is why we see 'budget' lines of premium motor makers (like the Emax Eco) doing so well in the market. Motors for 6 and 7 inch quads especially don't need these super strong materials because they don't tend to be crashed as much given they are typically used for long range flights rather than freestyle. Oh, big 9mm bearings mean smooth operation and good durability too.
Summary: Great quality to value ratio, similar to the Emax ECO in value proposition.

Size of the motors looks a lot more appropriate on this 7 inch quad now. Testing done with the big (and heavy) dalprop t7056c

Hollow steel shaft and multistrand windings

Hex screw to hold the shaft in place

Performance
Firstly these motors are 50g per piece which is 20g heavier than a typical 2306 or 2207. That's 80g over the quad and why I wouldn't recommend for a 5 inch quad. On a 6 or 7 inch quad that has the blade area to carry that extra weight, they are very, very nice. I could not believe the improvement over the top of the line returner R6 2306 motors I was using on the same quad, specifically:

• More control. Whereas I thought that 7 inch quads felt sluggish because of their size I was wrong - I just didn't have the right motor. Now I feel like this quad handles and moves like a 5 inch freestyle running a 2306 motor - I can maintain altitude close to the ground much more accurately and manoeuvres start and finish much more accurately. This control came in spite of the fact I ran the big, heavy Dalprop t7056c tri-blades instead of the much lighter HQProp 7x4.5x3 bi blade props I was running on the 2306 motors
• More power. This larger stator is more effective at spinning the prop up under high load rather than the 2306 which became saturated at around 70% throttle. As a result there is much more thrust and better resolution at the top end of the range. 
• Greater efficiency. Although this can output more thrust at the top of the throttle, the lower levels we typically fly at are much more efficient. I noticed I could maintain cruising speeds of around 70-80kph at much lower current draw than the 2306 motors which means it will suit long range runs and even freestyle flight a lot better. In fact where I was getting a disappointing 5 minutes using a 6s 1400mah battery with the 2306 motors, I now get over 8 minutes which you can see in the flight below.

Summary: More peak power, greater efficiency and the control of a 5 inch on a 7 inch quad. What's not to like?! 

From these 2306...

To these 2508

This flight went for 8 minutes on a 6s 1400mah pack. Resting voltage after flight was 3.75v per cell

Recommendation
If you are looking for a great budget motor for a 6 or 7 inch quad then this is arguably the one to have. Size and T-motor build quality make for a compelling option. It is on;y available at present in 1200kV which is a good option for 6s in this larger prop size. If you are wanting to get the top of the line motor then the Brotherhobby Avenger 2806.5 or Flywoo 2806.5 are very nice but the big extra cost only gives an incremental performance increase. As a result I''m very happy to recommend these as my favourite value motor for a 6 or 7 inch quadcopter build.

Brother Hobby 2806.5

Flywoo 2806.5

Racerstar AirA 2508 each

Racerstar AirA 2508 4 pack

The Racerstar AirA 2508 is available in singles or in a discounted 4 motor pack as above and are exclusive to Banggood. If I find these on discount I'll list on my coupons and discounts page.

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