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Old Dec 09, 2014, 10:10 AM
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United States, MO, La Plata
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help me get my Sky Scooter airborne

I decided this fall to resurrect my rather unsuccessful Sky Scooter.

My history is that I flew RC in the early 70s Had a balsa trainer powered by an Enya 19. Had several sucessful flights before eventually ending up in a pile I still have the motor.

Jumping ahead to about 2002 or 3 I got the sky scooter with the 300mah nicad, As I had heard that the plane flew pretty well.

My experience has not been too good. Then I tried flying it on a few occasions then put it away. It didn't have enough engine to gain altitude.

A week ago I got it out and bought a couple of NiMH batteries The stock Nicad was 8.4 volts so I got a 8.4 v and 9.6 v 700mah batteries. They were rated at 10 amps max discharge. I had thought about going with LiPo batteries but would be stuck with a nominal voltage of 7.4 or 11.1v. I didn't think 7.4 would be enough and 11.1 might just burn out the electronics or motor in short order with a starting voltage of 13 volts.

I charged the new batteries to 10.1 and 11.3volts at about .15C. Took out my 8.4 and got straight out disappointing results. I had a choice of gliding downward or keeping it level and stalling. After a couple of trials I switched to the 9.6v 2/3AA packs. The plane did a bit better.

Our property has a 9 acre pasture that is gently sloping. Making for theoretically easier starting. My longest flight was maybe 10 seconds before settling to the ground.

I brought it in and decided to bring the ailerons down 5 or 10ļ to get more lift. Today I took it back out but didn't charge up the 8 cell pack as it was still over 10 volts.

We tried maybe 10 or twelve launches on the slopes. The engine while turning fast was not really really putting out the air that my experience thought that it should be good enough to fly. I got some fairly long glides but no real climbing About the same as I remember back in the day.

I am recharging my 9.6 to a full 11.6 volts and will try it tomorrow if it isn't raining, snowing or windy.

I did take the gearbox apart there was still some grease in it. The Motor runs smooth. Doesn't get hot.

Any ideas on my old plane?
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Old Dec 09, 2014, 12:35 PM
yank and bank!!
Joined May 2013
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Any chance you put the prop on backwards?
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Old Dec 09, 2014, 12:39 PM
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United States, TN, Murfreesboro
Joined Apr 2013
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These older model's were not light and under powered and you had to be good to get them to fly at all. And today they make light planes with good power and systems to help you fly. I have a few of these old planes in my plane room never fly them. Got most at yard sale's my son can get them to fly not me. But I have over 16 other planes I do fly. These old models take great picture's , that's all. Get you a newer model and get flying and have some fun.
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Last edited by papadwight; Dec 09, 2014 at 12:45 PM.
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Old Dec 09, 2014, 01:09 PM
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United States, CA, San Diego
Joined Jun 2007
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+1 to checking the prop. Curved blade surfaces should be forward, flat to the back. Beyond that, while I didn't have the chance to experience those brushed motor, nicad powered planes, I understand they were low on power and high on weight. The modern brushless motors and lipo batteries are a quantum leap from those power systems. Your best bet would probably be to re-power that with a modern power system, but that's a bit of a science in itself to get the right setup. But some people like to tinker and do stuff like that, which is totally understandable. If you're not too into tinkering and would rather get flying, I think Papadwight is on the right track with just getting a new plane for now. They are so affordable and fly so well compared to the days of nicads. He has some good examples there. If you have the money, since it sounds like you have a big field, you may even want to go for something like the E-Flite Apprentice. It's bigger and can handle some more wind than some of those he mentioned. There are plenty of good trainers to choose from. It sounds like you had a little experience though, so I couldn't know just how much training you're in need of. Hard to tell through the internet!

If you want to get caught up with electric flight, here's a good read: EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
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Old Dec 09, 2014, 02:28 PM
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United States, MN, Eden Prairie
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Doesn’t it have a folding prop?
It’s not too likely to be backwards if it is folding.

David
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Old Dec 09, 2014, 02:31 PM
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United States, CA, San Diego
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Quote:
Originally Posted by Rhea View Post
Doesnít it have a folding prop?
Itís not too likely to be backwards if it is folding.

David
Well, I don't know. Never seen one and OP didn't provide a link. I didn't look to close to the few that popped up in a quick Google search. But if that is the case, then off course that can most likely be ruled out, and focus on the old power system.
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Old Dec 09, 2014, 02:54 PM
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When I purchased it back then I did so after research showing them amongst the best fliers. Mine trimmed to fly straight and level but won't climb.

Prop is stock and put on fine. It has a brushed motor gearbox turning a prop 8.5" diameter.

Here is a picture of someone (not me) with one.

His has a smaller prop, presumably without the gear drive.
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Old Dec 09, 2014, 03:48 PM
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Bishopville S.C.
Joined May 2003
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I have one that now uses a brushless motor and lipos, but it flew fairly well with the stock setup. Your idea to increase lift may sound good, but it will increase drag and may make launching more difficult.

A full throttle launch with a fairly fast toss helps. Let it build speed before using the elevator.

If you have a meter, you could test the battery voltage at full throttle. If it drops a lot it could indicate that the battery isn't up to the task.

It may be worth a try to discharge the battery then recharge it and test fly again while the pack is still warm from charging. They have a bit more oomph then, and a bit more might be just enough.
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Old Dec 09, 2014, 05:08 PM
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I guess there's a possibility a prop change might help. But it'd be a guessing game. Larger diameter gives more low speed thrust, higher pitch more top end speed. But it's not that simple, as there's an interrelationship between the 2. It's kind of like low and high gears in a car, but you only get to choose one gear. If you have a plane flying OK but want more speed, you could go up in pitch, but if you don't reduce the prop diameter, you may over-amp the power system and let the magic smoke out of one of the components. That's with the brushless motors, I'm not sure about brushed.

Your plane sounds like it's on the ragged edge of the power band. More low end power (Larger diameter prop) may be needed to get it up to flying speed, or maybe there just isn't enough pitch to get it going fast enough. But with a marginal power system, you may not have enough low end power to get up to that speed.

Wish I had a magic answer to this. Just contemplating what might be a simple fix. Heck, I just realized, if that plane was a marginally powered flyer to began with, if you live up in Denver or something, it could be just the thinner air is the issue.
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Old Dec 09, 2014, 05:18 PM
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HI
Just went out with my topped up new 9.6v battery. Had 3 flights over 150 yards, It climbed a bit on the first launch, maybe to 20-30 feet above launch point. The second and third flights didn't have the kick that the first did so I quit. After I flew it last time the 9.6 had a running voltage of 6.3. Resting voltage was 9.3, the battery had some minutes of flight time on it, I had probably launched it 15x times with flights in the 50 yard range.

This model doesn't have any throttle control. It runs full throttle till the voltage drops to some preset, then it cuts out for a dead stick landing. The controls are the elevator and ailerons

I have the flying surfaces set to not give me too much and I didn't apply the controls for more than a second or two. Probably still moving them further than needed.

I think I would do better if I could get the plane up 50-100 feet.

Good point about the model being old school and the new ones having a lot more going for them but this is the one that I have for the moment.

Thanks a lot for the many responses. They help.
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Old Dec 09, 2014, 08:56 PM
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The low voltage in use suggests a problem. How did you measure it? I lean towards the pack being too small, but those aren't the best connecters (if stock). They can be removed from the housing with a tiny screwdriver and cleaned with a pencil eraser to increase conductivity.

I used 8cells 1400AA kans in mine at one time. Heavier, but plenty of juice for 8 minutes of flight.
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Old Dec 09, 2014, 09:17 PM
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United States, MO, La Plata
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Thanks Ron I am going to test the voltage with a full battery pack and make an attempt at current, my meter goes to 10A, the same as the regulator.

What do you think of converting to LiPo for less battery resistance? Not sure how to deal with the individual cell leads.

The standard connectors are the std Tamiya.
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Old Dec 09, 2014, 09:59 PM
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Let me respond backward. The Tamiya aren't the best, but good enough for this model. I would verify input voltage as well as output. Your problem may be the connecter. Make sure that they are clean!
I'll skip the rest. Where are you? I may have just what you need.
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Old Dec 09, 2014, 10:02 PM
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United States, MO, La Plata
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No where near probably Am in Northern Missouri.

The battery packs are new but chinese.

Quote:
Originally Posted by Ron H View Post
Let me respond backward. The Tamiya aren't the best, but good enough for this model. I would verify input voltage as well as output. Your problem may be the connector. Make sure that they are clean!
I'll skip the rest. Where are you? I may have just what you need.
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Old Dec 10, 2014, 08:53 PM
Wake up, feel pulse, be happy!
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United States, AK, Fairbanks
Joined Aug 2009
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My first reaction would be to drop in a 2S lipo with a capacity of around 750-1000mAh, or else whatever it takes to nail the CG. It'll be lighter than your NiMH packs, and it'll hold way better voltage under load despite its lower nominal figure, so flying should work a little better.

Ok, I lied. My first reaction is to ditch the stock setup and drop in some modern equipment. A brushless motor, an ESC, and three lipos will run you maybe fifty bucks. If the plane has a proprietary or integrated RC system, you'll need to swap that out with standard gear. I'd say it's worth it for throttle control alone
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