KeninAZ

I have a new mini ultra stick on the way. I already had the recommended motor, a park 450 left over from my mini telemaster I used for a trainer.
I was going to use a 9x6 prop with this to start out but then I remembered the thinner air at 5400'+ that I fly at.
Would it be a good idea to start out with perhaps a 10x6 to compensate?

Wildflyer

Do you have a wattmeter? It is the single most important tool for electric flying.

I have found huge differences in power used and performance delivered, all with the same "size" of prop.

Some blade designs will use twice the power than others even though they were both 11x7 (in my case)

Basically the wattmeter will tell you the power the prop is using, so you don't burn up your good motor, (I try to be close to max, but not exceed it) then experiment with several different props, until you find the one that you like best.

I'm sorry I can't give you a perfect size to try (I haven't joined the mile high club yet), but you have a great plane. One of my best flying friends, has worn out 5 Mini Ultra Sticks, and is on his 6th, he is a great flyer of any airplane type you can name, some of his plane have had 2000+ flights. I value his opinions of different planes very highly.
I am going to scratch build a Mini U S for this summer.

KeninAZ

Yes I have a watt meter but for my question I am not sure it's going to tell me much.
And I am also aware that the 10x6 is well within the range for the MUS and this motor. eFlite actually recommends a 10x7 or 11x7 for this motor/plane combo but I am trying to stay with a little slower flying plane as I am a rookie.
All I am looking to do is compensate for the thinner air and I did not think the watt meter would tell me flight characteristics for 5400'.

dkrhardy

I use a 10X7 on mine and it is not a speed demon. You can fly at 50% power ... remember, YOU control the power. No need to be blasting around at 75-100% power if you don't want to.

KeninAZ

OK, I think I will move up to the 10x6 props that I own already and start there.
Thanks for the input. The 9x6 may not have been enough at this altitude

AEAJR

The wattmeter is the perfect tool for your task.

You think that the prop will not produce the power you expect due to the thinner air. The best way to validate that is to run it on the wattmeter.

If a given prop pulled 16 amps at sea level, does it pull less st 5400 feet?. If it does, then you may need to prop up. If it is the same then no need make a prop change.

We prop to the amp draw of the motor. You can favor wide for better climb or you can favor deep for higher speed, but ultimately you prop to the amp draw of the motor. And I would usually prop toward the max amps allowed by the motor, the ESC or the battery, wherever your limiting factor lies.

KeninAZ

OK, I just plugged my watt meter in with a 10x7 prop that they recommended for the plane with the Park 450 motor.
The air on my bench is as thin as it's going to get or so I must assume here in 5400' or so and I pulled right at 160 watts average with a draw of 13.15 amps on my 3s battery.
The motor is rated for 14 amps max with a burst rating of 18 for 15 seconds so it appears that thin air or not that this prop is just right.
I don't have the smaller ESC that that I ordered yet so I don't know the true weight of the plane ready to go but I am going to assume around 25-27 Oz. so that should put me just over 90 watts per pound and that should be very nice.
As a rookie, this is my second plane, I doubt I will be hitting full throttle much anyway, at least in the beginning.
I have been thinking about programming flaps for this one but I have to figure that out on my DX 7 yet.
I did use both the aileron and the aux inputs on my receiver so I can have flaps, at least I think I have that correct so far.
But I have also read that you don't really need flaps so for now I won't have them.

AEAJR

Yes, I would agree that you have a good match there.