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Old Oct 06, 2012, 07:03 PM
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Quote:
Originally Posted by The Don View Post
If you had a better understanding of how electric motors work then you would know why it will run on 4S with no issue.

This thread makes me think of these:

http://www.youtube.com/watch?v=flityqF_AKw

http://www.youtube.com/watch?v=Kkue1ns4XvU
Well put Don. The ability to reverse the prop in flight? What a concept!
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Old Oct 06, 2012, 07:13 PM
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See the Technical Info/FAQ page for the Super Sky Surfer at http://www.rcgroups.com/forums/showt...6#post22886340

Quote:
Originally Posted by kaptondave View Post
Well put Don. The ability to reverse the prop in flight is the next big thing in model aviation.
See VRA: http://en.wikipedia.org/wiki/Ryan_Navion

Wiki doesn't mention that it had a reversible-pitch prop (since the engine couldn't run backward) that we used in flight for fast decelerations and steep descents. Easier to judge when your rear is in the seat, than when you're trying to guess speed from the ground of an aircraft whose airspeed is no longer so dependent on nose attitude and engine speed.
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Old Oct 07, 2012, 01:26 PM
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Flew the SSS today with the 60A ESC, the EMP 3-blade 8x6 prop on the original stock motor, and two 2s 4000mAh R/C car batteries. That extra weight in the nose makes all the difference, the plane didn't stall once and flew very smoothly. Climbed out well at about 3/4 throttle, circled around etc., it's now a pleasure to fly.

Tried several turns and tested to see how it recovered from banks. It basically didn't. Bank it over, go around a turn and let the stick come back to center, and it stays banked over and continues turning. With correct aileron trim it did this equally in both directions, similar to what most real planes do. It takes a positive aileron input the other way to bring it out, typical for a wing with little or no dihedral.

No real surprise, of course, most planes are this way. R/C planes for beginners usually have enough dihedral to automatically roll out of turns, the SSS is not quite a beginner plane for this reason.

Landed (on the second try, this thing still floats forever, even with the flaps down) and noticed that the canopy cover had come loose. Turned out that the magnets on the fuselage, had decided to take a vacation and were stuck to the magnets in the cover. I'll sic the file and epoxy on them in a minute.

Didn't do a second flight with the loose canopy, so didn't have a chance to find out how well it climbs with the 4s battery and 3-blade prop, but did manage to do my first (poweroff) loop with this plane. Very pretty. Motor and ESC were only slightly warm after landing, but that's after a long poweroff glide as usual, not a good test of overheating. I never went to full throttle on this flight.

Plane is slightly noseheavy now (CG about 93mm from the leading edge), and flies like it, nice and stable. I have no problem recommending this as a good CG location. Haven't tried the one listed in the manual (100mm), but I'd guess that one is good too. So this starts to look like the beginning of an "acceptable" CG range: anywhere from 93mm to 100mm behind the leading edge of the wing, is probably a good place to have it.

I found out earlier that having the CG at 104mm (slightly tailheavy), makes the plane hypersensitive in pitch, it stalls a lot, bobs its nose up and down etc. Flyable, but it's annoying, you are always correcting it in pitch. I'd recommend against having the CG that far back.
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Old Oct 07, 2012, 02:23 PM
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Good report. Ok, from 1 to 10 how "much better" did it fly with the 3 blade as appose the last setup you flew with....10 being the highest. And are you thoroughly satisfied? If not, why?
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Old Oct 07, 2012, 02:59 PM
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Originally Posted by G-LO View Post
Good report. Ok, from 1 to 10 how "much better" did it fly with the 3 blade as appose the last setup you flew with....10 being the highest. And are you thoroughly satisfied? If not, why?
Climbed out at 3/4 throttle (with 3-blade 8x6 prop, 4s battery) about as well as it had on the original stock prop and GensAce 3s battery.

I didn't get a chance to fly it full throttle, it's reasonable to assume the climb will be better of course, but can't guess "how much better". The first flight on any new setup, especially with different weight&balance, is always a mellow flight with me, I don't push it cuz it might push back. Canopy came loose and I didn't want to lose it, so didn't fly any more this morning.

BTW, just ordered one of these:
http://www.headsuprc.com/servlet/the...ushless/Detail

I'm hoping for a climb in the 9-10 range on your scale with a good 5s battery and a 9-6 3-blade prop with this motor, probably use a 100A ESC. But you never know until..... Even though I'll likely spend most of the time with this motor at half throttle or less, letting the SSS be an SSS.
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Old Oct 07, 2012, 03:12 PM
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Hey man, Nice find!

The motor that I bought there is the size of the stock motor, but the windings isn't as extensive. I'm wondering if it will do any better in the long run? I'll see after I get everything in place.
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Old Oct 07, 2012, 06:41 PM
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Originally Posted by G-LO View Post
LA, please check your SSS you Started. 2 BH Reps chimed in....
Done. Thanks for the heads-up.
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Old Oct 07, 2012, 08:13 PM
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Quote:
Originally Posted by kaptondave View Post
Well put Don. The ability to reverse the prop in flight? What a concept!
Glad to hear someone else thinking of the ability to reverse thrust
I haven't built my x8 wing yet, but these wings float forever when trying to land, I mentioned the same idea of using a car esc to reverse thrust, just to be used briefly to be able to wash off airspeed to land shorter. I was hoping I might be able to somehow mix in a switch to enable throttle to go into reverse... I don't know if I'll be brave enough to try it, going to have to substantially strengthen the motor mount if I ever do try it
Anyone heard this attempted?
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Old Oct 08, 2012, 12:48 AM
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Quote:
Originally Posted by The Don View Post
If you had a better understanding of how electric motors work then you would know why it will run on 4S with no issue.

This thread makes me think of these:
Very well said. +1.
AJ
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Old Oct 08, 2012, 10:35 AM
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Quote:
Originally Posted by kaptondave View Post
Well put Don. The ability to reverse the prop in flight? What a concept!
It works for Martin Muller! Just under two minutes in >

World Air Games 2009 (Torino) Martin Müller (3 min 14 sec)


Without a doubt the most amazing routine I have ever seen.

Gord
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Old Oct 08, 2012, 10:48 AM
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Quote:
Originally Posted by The Don View Post
If you had a better understanding of how electric motors work then you would know why it will run on 4S with no issue.

This thread makes me think of these:

http://www.youtube.com/watch?v=flityqF_AKw

http://www.youtube.com/watch?v=Kkue1ns4XvU
Thanks Don! Those videos will be downloaded and saved. They made my morning.

Gord
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Old Oct 08, 2012, 12:00 PM
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Originally Posted by Gordks View Post
It works for Martin Muller! Just under two minutes in >

https://www.youtube.com/watch?v=MlRM2ewfzmY

Without a doubt the most amazing routine I have ever seen.

Gord
Incredible.

I'd never, ever try that, even if I had his exact plane... in fact, if someone told me they had done it, I'd call him a liar to his face.

But seeing it live like that... whoa.

In most (but not all) of his routine, he's using the propeller ONLY, for generating all needed lift to keep his plane aloft.

Gets trickier if you're using your wing to generate virtually ALL lift, and using the prop (forward or reversed) only to regulate forward speed. As I said earlier, if you get too enthusiastic with the prop in reducing speed, you can easily go below stall speed of your wing, and suddenly fall out of the sky. Drag created by flaps, is reduced as speed is reduced. But "drag" (or rearward thrust) created by reversing the propeller rotation while flying forward, does NOT diminish as the plane slows down, and might even INCREASE as the plane slows. This can give "catastrophic event" a whole new meaning.

We had a reversible-pitch propeller in a Navion (real plane) when I was an aero engineering student (see http://en.wikipedia.org/wiki/Ryan_Navion , scroll down to VRA), controlled by an analog computer in the back seat. Apparently it was replaced by a digital computer after I left. The computer was also hooked to the aerodynamic controls, of course. The purpose was to make the Navion behave like a different plane in flight (B-52, 747, Ford Trimotor etc.), essentially an airborne simulator that cost a lot less to fly than the actual B-52. The Navion was flyable with the prop reversed as long as you kept a sharp eye on the airspeed, and a thumb poised over the red button at all times. Having your butt in the seat and feeling the plane accel and decel, feeling the stall shudder etc. made it more possible.

But on a model plane you don't have an airspeed indicator (except the very few using telemetry), no seat-of-the-pants feel, and not much of a red button, depending on how you set up your reversing. With a model we judge forward speed by watching from the ground and guesstimating the effect of wind, plus nose attitude. But with a reversed prop, nose attitude doesn't matter as much, and speed can change pretty suddenly, and unexpectedly (at least the first few times you try). Experimenting with this in a model, is going to be hairy.

Well, that's why it's called experimenting... I wonder how many planes that guy in the video crashed, before he got it to fly like that?
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Old Oct 08, 2012, 12:23 PM
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Two more successful flights this morning. The SSS is sweet with the CG at 93mm, definitely not "too noseheavy". Did some power-on and power-off loops, also did my first ROG (Rise-off-ground) takeoff with this plane from the grass. Got some cheers from spectators at the park when it lifted off - people like such a big plane!

It does climb noticeably better with the 4s battery setup, stock motor, and three-blade 8x6 EMP prop. G-lo, you mentioned a scale of 1 to 10. With the stock prop and motor and a 3s battery I'd give it maybe a 2. With the 4s and 3-blade prop this morning, it's around a 5 or 6. (A sustained vertical climb would be a 10, don't know if I'll ever achieve that, even with the new motor that's coming). This morning it was climbing continuously at about a 30-degree angle, which is fairly impressive looking for a large and relatively slow plane like the SSS.

When it landed the 60A ESC was only slightly warm to the touch, nothing worrisome, and the motor still felt room-temp cool, as did the 14ga battery wires on the ESC. But that was after a fairly long power-off glide to landing, of course, I'm sure it warmed up pretty good during the full-power climbs. The motor gets pretty good air circulation, but the ESC gets virtually none. 4s and a three-blade 8x6 prop with wide blades, is pushing the stock motor pretty hard, I'm sure.

For these flights, flaps seemed more effective. Maybe I just misjudged them in the first flights. Or maybe I was flying at higher angles of attack, and slower, while not compensating properly for the aft CG on those early flights, and so lowering flaps didn't do much more. Pilot error is still responsible for most strange aircraft behavior, sad but true. But this morning I thought it was descending at a noticeably steeper approach angle, and touched down both times right in front of me rather than floating the entire length of the park as it often did before.

I still saw no signs of any added nose-up or nose-down tendency when flaps were lowered. Dropping the flaps, even suddenly, made no apparently difference in flight characteristics (that's unusual but very welcome).

Whatever. I really like the way it flies now.

But I'll still probably try reversing the prop eventually.
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Old Oct 08, 2012, 01:03 PM
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I agree with you LA. Everyone started at one point in there understanding of anything . That's why they are called experiments. If the others said .."did that, done that, and ain't gonna work " maybe you're in that same process. We are all on that journey Everyone-

But I do, to a degree, understand why some may be bothered or irritated by a person posting "their first time experiments". I guess folks who understand about electronics want others to be safe while their on their journey of understanding.... perhaps

I guess what I'm trying to say is; I didn't understand when someone said .." If you had a better understanding of how electric motors work then you would know why it will run on 4S with no issue." I don't know about anyone else, but I wasn't aware of it. I didn't know... ( Even Dr. Kiwi is still findind out stuff). I'm not afraid of saying. We all here on RCG come from all walks of life with varying degrees of education and knowledge. Hey, help me ...I'm still learning. I'm TRYING to learn from the best...
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Old Oct 08, 2012, 02:22 PM
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Originally Posted by G-LO View Post
Hey man, Nice find!

The motor that I bought there is the size of the stock motor, but the windings isn't as extensive. I'm wondering if it will do any better in the long run? I'll see after I get everything in place.
The one I mentioned is nice because, from the data presented by HeadsUpRC, it looks like I can plug it in (once I get the motor mount figured out) and use it with my present 60A ESC and 4s battery setup, and get 500+ Watts with the APC 9x6E 2-blade prop that's already in my field box... and may be able to try the 9x6 three--blade too, also with 4s.

And then if I put in a 100A or so ESC and 5s battery, it might approach 800-1000W with the 9x6 3-blade, and maybe more static thrust than the weight of the plane (presently weighs about 82 ounces).

Quote:
Originally Posted by HeadsUpRC
http://www.headsuprc.com/servlet/the-2246/Emax-BL3526-fdsh-04-Outrunner-Brushless/Detail

Propeller data for the BL3536/04 using a 5-cell Lipo battery:

APC 10 x 5E: 112 oz thrust at 52 amps (1000 watts)
APC 9 x 6E: 92 oz thrust at 47 amps (930 watts)

Propeller data for the BL3526/04 using a 4-cell Lipo battery:

Master Airscrew 11 x 7 x 3 (3-blade prop): 99 oz thrust at 60 amps (910 watts)
APC 10 x 7E: 83 oz thrust at 47 amps (730 watts)
Master Airscrew 10 x 7 x 3 (3-blade prop): 91 oz thrust at 49 amps (750 watts)
APC 9 x 6E: 66 oz thrust at 34 amps (530 watts)
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