Flight times are insane
09-22-2004, 06:59 PM
#1
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Flight times are insane
Hey all
I just converted my Accipiter Badius ( a slope diver) from a S400 motor, cheap speed controller, a 6X3 folding prop, and 7 cell 1,100 Mah 2/3 A to a, Motor Max 400T, Phoenix 25, Graupner 8X4.5, and a 2 cell Li-Poly at 2,200 Mah.
My absolute best flight time with the original set up was 25 min, I was following some thermals.
I did a bench test with my new set up, it ran at full power for 20 min, I figured actual flight should be longer.
My first timed flight was only 16 min because of darkness, when I got home I ran ( full power) the battery down, I timed an additional 15 min, I was pleased/surprised.
Tonight was very windy but I flew anyways, I didn’t want to dead stick in with winds like this. I set a timer for 30 min and gave the plane a toss. This new motor set up handled the wind quit well and after the 30 min I landed.
Being curious I started a timer and ran it up to full power to see just how much I had left.
9:53, I was floored, I did some quick math that told me for every 5 min I got of full power static test time, would translate in to 15 min of cursing time. It also told me I only needed 2 amps to the brush less motor to cruse (WOW what efficiency, S400 63%, new motor 88-91%).
This is INSANE, who has the need to have a plane aloft for 60 min ( projected).
I was told in a different thread “ once you go brush less, you’ll never go back”, I expected a small performance and flight time increase, BUT not this.
An amazed, brush less convert
I just converted my Accipiter Badius ( a slope diver) from a S400 motor, cheap speed controller, a 6X3 folding prop, and 7 cell 1,100 Mah 2/3 A to a, Motor Max 400T, Phoenix 25, Graupner 8X4.5, and a 2 cell Li-Poly at 2,200 Mah.
My absolute best flight time with the original set up was 25 min, I was following some thermals.
I did a bench test with my new set up, it ran at full power for 20 min, I figured actual flight should be longer.
My first timed flight was only 16 min because of darkness, when I got home I ran ( full power) the battery down, I timed an additional 15 min, I was pleased/surprised.
Tonight was very windy but I flew anyways, I didn’t want to dead stick in with winds like this. I set a timer for 30 min and gave the plane a toss. This new motor set up handled the wind quit well and after the 30 min I landed.
Being curious I started a timer and ran it up to full power to see just how much I had left.
9:53, I was floored, I did some quick math that told me for every 5 min I got of full power static test time, would translate in to 15 min of cursing time. It also told me I only needed 2 amps to the brush less motor to cruse (WOW what efficiency, S400 63%, new motor 88-91%).
This is INSANE, who has the need to have a plane aloft for 60 min ( projected).
I was told in a different thread “ once you go brush less, you’ll never go back”, I expected a small performance and flight time increase, BUT not this.
An amazed, brush less convert
09-25-2004, 12:22 AM
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RE: Flight times are insane
Man, you got that right! I need lipos in my TX to keep up with these airborne bunny batteries! It is sweet. I fly differently now- and I fly a lot more than I ever had. Charged it last week? No problem. Grab it and fly it.
I fly a lipo powered Ascent, 52" or so glider w a 7.2V S400, 6/3 folder and a 1500ma 3-cell lipo pack. It can fly all afternoon on a charge when its soarable. It gets hot in there and I replaced this one 3 times this season, widening the cooling hole again. It's going brushless, geared 3.33, this weekend- if I can find a 5mm hub and spinner for a folder.
I got the 7.2V S400s for $3 apiece so it was no problem to change em out monthly during soaring season. Compared to the cost of a brushless, that'd be.. ummm...a lot of S400s! But why use super batteries when the motor wastes half of the power?
Brushless is the mechanical breakthru that rivals- and compliments- lipos electrochemical advances.
Now to build our planes from IMPERVIUM!
I fly a lipo powered Ascent, 52" or so glider w a 7.2V S400, 6/3 folder and a 1500ma 3-cell lipo pack. It can fly all afternoon on a charge when its soarable. It gets hot in there and I replaced this one 3 times this season, widening the cooling hole again. It's going brushless, geared 3.33, this weekend- if I can find a 5mm hub and spinner for a folder.
I got the 7.2V S400s for $3 apiece so it was no problem to change em out monthly during soaring season. Compared to the cost of a brushless, that'd be.. ummm...a lot of S400s! But why use super batteries when the motor wastes half of the power?
Brushless is the mechanical breakthru that rivals- and compliments- lipos electrochemical advances.
Now to build our planes from IMPERVIUM!
09-25-2004, 09:51 PM
#4
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RE: Flight times are insane
Extended bench runs are NOT recommended. Most electric power systems need the forward motion of the airplane to push adequate cooling air past the motor and the battery. "Why? The props pushing all kinds of air!" you might say. 90% of that air is around the outside 10% of the prop blade, nowhere near the motor or battery in most cases. On the bench, the center section of the prop is pushing little, if any air because it's so steeply pitched.
