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| JustGoFly 450DH | |||||||||||||||||||||||||||||||||||||||
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Specifications Weight - 55 grams, |
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| My thanks to Vinnie of www.justgofly.com for the supply of this motor for testing. The 450DH is a 4000kv brushless motor and a brand new entrant in the brushless motor market. It is at the light weight end of the spectrum for a T-Rex motor with a weight of 55g. This makes it one of the lightest motors tested to date. Fitting the motor proved to be very straightforward using 2.5mm allen nuts to secure the motor to the motor mount. I fitted a 9T pinion initially but headspeed was off the scale so I changed to an 8T. I'm also using the Hyperion Titan 30A ESC for this test as I'm currently testing this ESC for a review soon to be appearing on TrexTuning. I did a test spool up to measure headspeed. The figures returned a willingness to head up beyond 2700 RPM, so I had to use the curves to keep the wood blades within specification of 2400-2500RPM. Unlike it's smaller 400DH cousin the 450DH has reasonable thickness wires, which proved to be for good reason as the test progressed. The 400DH is a very powerful little motor, the 450DH is a fair bit bigger, so I was expecting some real power from this little outrunner. I'm going to run one test for the 450DH, using stock wood blades. The test will follow the format in the table below. I have decided not to run the carbon blade test as I know from my own testing that the amp draw will go beyond 30amps and I don't have a pack that can cope with this level of consumption, not even the mighty Kokam 2000mAh can deliver beyond 30 amps. The test was conducted in an ambient 20 degrees centigrade, 68 degrees Fahrenheit. The pitch range on the T-Rex being from +/- 10 degrees. The power source was a Kokam 3S 2000mAh pack. The test are charts are created from the CSV data from the Hyperion Emeter which shows Volts/Amps and RPM on one chart and Watts on a separate chart. |
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| The 450DH recorded the following maximum values : 29.07 amps 12.5 volts 275 watts The recorded minimum voltage was 9.58 volts during the 30 second pitch pumping. The motor temp at the end of the test was 30 degrees centigrade, 86 degrees Fahrenheit. The lithium pack reached a max temperature of 43 degrees centigrade, 107 degrees Fahrenheit. All of this is well within specification and nothing of concern. During the 30 second climbout the headspeed didn't drop, in fact if I increased my maximum throttle curve point to allow it the headspeed would actually pickup during the full pitch / throttle, this has never happened on a motor test before. This is a very very powerful little motor. There are some things to note from the graphs above : At the end of the 30 seconds of full pitch the ESC had got so hot from running at close to its maximum output that the ESC started to shutdown, which explains the blip in the RPM. During pitch pumping the same happened and a loss of headspeed resulted. If the ESC was higher rated it would have carried the motor a little better. Based on some further testing with a higher specification (35amp) ESC I couldn't get the 450DH to bog at all and if anything it would just speed up when given full throttle and full pitch. If anything this motor suffers the same issues as the previous most powerful motor (Medusa 28-40-3400), which is amp draw. Whilst it will happily power the stock 315mm wood blades, anything more than this (longer or carbon) pushes the amp draw beyond any pack that I know of that could cope. In fact it would require a higher mAh pack to get back within specification, which of course may not be a problem with this much power readily available, although size issues on a T-Rex become a problem beyond 2000mAh packs. As I don't have anything rated more than 30 amps continuous. I can't test this performance with carbon blades without potentially destroying a perfectly good pack. The 450DH does have an abundance of headspeed, so if it were possible to get a pack that could cope, this motor would be awesome with some SAB carbon blades. Although the flight would not last long due to the large amp draw. I think what we are hitting now with these newer more powerful motors is the limit of what can be done sensibly with a 3S pack using the currently available battery technology. Lithium packs will need to make another performance step change to really take advantage of this type of motor, plus they will need to get lighter so that more mAh can be carried to get the preferred 10 minutes or so of flight duration. For the moment this is the most powerful motor I have seen for 3S use but I would have some reservation in recommending it based on the very large power requirements to run it effectively. Until battery technology catches up this is only for those wanting maximum perfromance on 3S but at the expense of short flight times and reduced lifetime on your lipos. Flight tests resulted in further ESC shutdowns but whilst the motor and ESC were behaving power was extremely good. I didn't push the flight testing too much as I was wary of overloading the Kokam pack and my ESC. Suffice to say that the perfrmance in the air mirrored the good power results on the test bench but also exhibited the same current problems. This motor is effectively before it's time and once lipos catch up with the demand this motor can create it will be one demon of a motor in the T-Rex. For now it is on my shelf waiting for that time. |
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