Newbie - Pleae HelpMe !! Trying To Fly My New Pico-Cub

jerrysimon · Jan 06, 2001, 03:36 PM

Spent a week putting it together. Taped it up with nice yellow tape. First flight knocked the motor mounting off when I eventually threw it. Having unsuccessfully ROG, I hand launched it :-( (I included the 400L gearbox for ROG). Forgot to check CG :-(

Second flight (now correct CG but heavier with balance weight_ started to ROG went up about 3 feet and then back down on the tail. Again after hand launch, landed on nose and snapped propeller. Began to think it was too heavy (750g) Spent half a day taking the tape off :-(

Now weighs 625g including weight for balance. Third flight still starts to ROG and then falls back on tail. Threw it (hand launch) again this time went up well 12ft but came down quickly. Second time on hand launch came down on nose. This time whole nose snapped off.

Anyway it's fixed again but I am confused. It appears not to have enough power to deliver the speed to lift it continually. It's built exaclty to the instructions (a little heavier than the 550g quoted but has the gearbox as well). So that leaves the batteries. They are Sanyo 6*AA 7.2V 700mAh Nicads, which look the same as those in the TX. They are what the model shop provided me with but I don't think they are right. I have measured the current being drawn when the motor is running full turning the prop, and it's drawing 1.2amps. (prop is the one that comes witht he gearbox 17.5/16cm)

The batteries are not marked AR/AE etc and I am beginning to think I have the wrong ones ? so have just ordered Sanyo 600AE's (pack of 6) from another shop who confirmed that they are wrong.

Anyone care to tell me where I am going wrong ? This is sooooo frustrating. Should the motor be drawing more current 3amp+ at full throttle. ?

Thanks in advance

Jerry

hoppy · Jan 06, 2001, 04:20 PM

I think you'll find that it should be drawing close to 8-9A at full throttle. My 6oz BUD needs 1.2A to fly. If your Amp measurement is correct, something is seriously wrong with the power train....ESC/motor/gearbox/prop/battery.
Is the ESC self calibrating to throttle range?? Is the battery fully charged?? Is the gearbox the 2.3:1 400L?? Is the prop a 7X6.5? Is the prop on right(lettering facing front)?? Is it turning in the right direction?? GoodLuck
Hoppy

jerrysimon · Jan 06, 2001, 04:27 PM

Hoppy,

Thanks for replying so quickly :-) The motor was tested outside of the plane (i.e. standalone) the battery was fully charged and I tested it with a multimeter in series (not shorting). This being my first plane I have no idea what sort of pull I should be getting full throttle ?

Jerry

jerrysimon · Jan 06, 2001, 06:33 PM

Drat!! I have double checked and the battery was not fully charged. I have re-charged it and retested the motor. It's now drawing 5.25 amps when connected directly to the motor. So I am back to where I started, why does it not appear to have enough pull to lift it more than 3 feet off the ground ?

I have re weighed everything and it comes out at 600g or 21oz.

Help..............

leccyflyer · Jan 06, 2001, 07:23 PM

Hi Jerry

Your Pico Cub should fly fine with those weights and the gearbox. Multiplex state 590-675g estimated AUW - my son's weighs in at 605g with a tape covered fuselage- we haven't decided on whether to tape the wing or not yet.

I've seen the Pico Cub ROG in about six-eight feet and climb very quickly into a brisk wind with the gearbox, very impressive. So there is probably something simple amiss with your power train somewhere. I'm sure you will be able to locate and cure the problem.

Firstly are you sure the prop is rotating in the right direction?- you will have needed to reverse the connections to the motor (black lead to the positive) if using the gearbox.

Is the main gear slipping at all on the main shaft? - there is a little grub screw to retain it.

You say you batteries are fully charged- is this the first time they have been charged- maybe they need to come up to spec?

Any of the above or perhaps that your ESC is not giving you the full throttle range are possible explanations for the reduced power you are seeing. What make and model of speedo are you using- does it have a little screw to adjust the motor maximum RPM or a particular start up sequence (TX on-throttle closed-RX on or similar) to initalise properly?

Good luck with the Pico Cub

cheers

Brian

Fred Bronk · Jan 06, 2001, 08:09 PM

Are you sure 6 cells are enough, what is the motor?

Is the prop on the correct way, IE facing forward?

hoppy · Jan 06, 2001, 08:21 PM

That amperage is better.
Well, if the prop is on correct and is blowing the air back, then lets look at the balance. How much balance weight did you add? Where did you add it?

When it takes off, does it tend to go straight ahead or rise sharply by itself?
Same question for the hand launch?

You should let the plane fly level for say 100-150' before giving it much up elevator so it can gain flying speed.

If it is going up by itself, you have either..(1) an up elevator at neutral stick setting, or (2) the plane is tail heavy.

Are you taking off at full throttle? If you have a small scale, ie ozs, attach it to the tail and fire it up. Should read 7-8 oz (196+g).

More later..
Hoppy

jerrysimon · Jan 07, 2001, 12:44 PM

Hey thankyou very much for your replies and sugestions. Anyway fixed it for the third time. Fourth flight today. Waited until late afternoon when everyone had gone home from the park and the wind was "almost" still.

I was definately putting on too much elevator. This time is ROG and stayed aloft for about 30 second but gained no more than 3-4 feet in height before coming down.

Power is DEFINATELY the problem. The guy in the shop sold me 6 * AA (7.2v 700mAh) Nicads
which I think are the ones for a Tx not the short stubby AE/AR. The ones he gave me also have a label that says charge @70mA for 14-16hrs.

Anyway I have now ordered some Sanyo 6 cell 7.2V 600mAh AE ones which will arrive tommorow. At least then the model will be exactly as specified on the box.

Just a thought maybe I should have ordered the 7 cell ones, although I was worried that they would burn out the motor faster.

Jerry

jerrysimon · Jan 07, 2001, 02:55 PM

Yes it freezing here! My daughter came out with me to catch it all on video. They (the rest of the family) then come back and have a hoot watching me smash it up :-(

As you say it's good to come back with it still in one piece. Anyway I will update you all tommorow when I get the new batteries.

Once again thanks for all the advice. It great to have a resource like this to bounce problems off.

Jerry

hoppy · Jan 07, 2001, 03:48 PM

I definitely think the temperature may be a factor. Are the batteries warm when you start? My batteries are NiMH and really lose zip when the temp is low...low being 45 here in Florida. It took one more cell to bring them back to where they were when it was warm.
Hoppy

jerrysimon · Jan 07, 2001, 06:10 PM

Hoppy,

Just noticed reading through the blurb on my Jeti 180 ESC, it has a brake on it ? It says this can be turned off by plugging in the jumper. At the moment the jumper is not fitted i.e the brake is enabled ?

Jerry

hoppy · Jan 07, 2001, 07:17 PM

Jumper off-break on
Jumper on - Break off

It was recommended to me by US Jeti distributer to put the jumper on - break off.

Hoppy

ps I noticed during bench tests that my motor puts out significantly more power when batteries are at 60deg as opposed to 40deg. About 15% under static conditions. The plane I've been flying is marginally powered and during this cold spell it just doesn't want to stay in the air...very similar to what you have described. Adding 1 cell has made it flyable again.

Travis · Jan 07, 2001, 07:24 PM

jerry, the "brake" you refer to simply means
that when the BEC cuts the motor at low voltage, the prop will not windmill during
the glide. (a windmilling prop is a big air-
brake and will make a model drop like a rock
when the power is off). the brake is also
nesesary when using a folding prop.

Keep those batteries in your pocket untill
your ready to take-off. If you have any
battery cooling vents block them off untill
it gets warm outside.

Mark Wood · Jan 08, 2001, 01:02 AM

Sure sounds like a voltage problem. What's the voltage rating on your motor? Nobody has asked that one yet. Running up to 8 cells on a 6 volt motor or 10 on a 7.2 volt one is acceptable. We actually got a friend's Hobbico SkyRunner to fly simply by adding a sixth cell to the useless 5 cell pack that was supplied with the plane.
MORE POWER! (grunt grunt grunt)

mw

leccyflyer · Jan 08, 2001, 01:06 AM

Jerry

The instructions with our Pico Cub specify 6x600mah AA batteries- not the dumpy 600AEs you refer to- though I suspect either would do. You could easily add an extra cell (or two) as well - especially if your model was supplied with a 7.2v Permax rather than the 6v version.

Did you buy this as a made-up pack or did you make the pack up yourself? What are you using for a charger?

Jan 06, 2001, 03:36 PM	#1
jerrysimon Crashing IS Flying Join Date: Jan 2001 Location: Cambridge, England Posts: 1,403	Newbie - Pleae HelpMe !! Trying To Fly My New Pico-Cub Spent a week putting it together. Taped it up with nice yellow tape. First flight knocked the motor mounting off when I eventually threw it. Having unsuccessfully ROG, I hand launched it :-( (I included the 400L gearbox for ROG). Forgot to check CG :-( Second flight (now correct CG but heavier with balance weight_ started to ROG went up about 3 feet and then back down on the tail. Again after hand launch, landed on nose and snapped propeller. Began to think it was too heavy (750g) Spent half a day taking the tape off :-( Now weighs 625g including weight for balance. Third flight still starts to ROG and then falls back on tail. Threw it (hand launch) again this time went up well 12ft but came down quickly. Second time on hand launch came down on nose. This time whole nose snapped off. Anyway it's fixed again but I am confused. It appears not to have enough power to deliver the speed to lift it continually. It's built exaclty to the instructions (a little heavier than the 550g quoted but has the gearbox as well). So that leaves the batteries. They are Sanyo 6*AA 7.2V 700mAh Nicads, which look the same as those in the TX. They are what the model shop provided me with but I don't think they are right. I have measured the current being drawn when the motor is running full turning the prop, and it's drawing 1.2amps. (prop is the one that comes witht he gearbox 17.5/16cm) The batteries are not marked AR/AE etc and I am beginning to think I have the wrong ones ? so have just ordered Sanyo 600AE's (pack of 6) from another shop who confirmed that they are wrong. Anyone care to tell me where I am going wrong ? This is sooooo frustrating. Should the motor be drawing more current 3amp+ at full throttle. ? Thanks in advance Jerry

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Jan 06, 2001, 04:20 PM	#2
hoppy Registered User Join Date: Oct 2000 Location: Key West Posts: 13,109	I think you'll find that it should be drawing close to 8-9A at full throttle. My 6oz BUD needs 1.2A to fly. If your Amp measurement is correct, something is seriously wrong with the power train....ESC/motor/gearbox/prop/battery. Is the ESC self calibrating to throttle range?? Is the battery fully charged?? Is the gearbox the 2.3:1 400L?? Is the prop a 7X6.5? Is the prop on right(lettering facing front)?? Is it turning in the right direction?? GoodLuck Hoppy

Jan 06, 2001, 04:27 PM	#3
jerrysimon Crashing IS Flying Join Date: Jan 2001 Location: Cambridge, England Posts: 1,403	Hoppy, Thanks for replying so quickly :-) The motor was tested outside of the plane (i.e. standalone) the battery was fully charged and I tested it with a multimeter in series (not shorting). This being my first plane I have no idea what sort of pull I should be getting full throttle ? Jerry

Jan 06, 2001, 06:33 PM	#4
jerrysimon Crashing IS Flying Join Date: Jan 2001 Location: Cambridge, England Posts: 1,403	Drat!! I have double checked and the battery was not fully charged. I have re-charged it and retested the motor. It's now drawing 5.25 amps when connected directly to the motor. So I am back to where I started, why does it not appear to have enough pull to lift it more than 3 feet off the ground ? I have re weighed everything and it comes out at 600g or 21oz. Help..............

Jan 06, 2001, 07:23 PM	#5
leccyflyer Get One Up! Join Date: Sep 2000 Location: Cheshire, England Posts: 9,302	Hi Jerry Your Pico Cub should fly fine with those weights and the gearbox. Multiplex state 590-675g estimated AUW - my son's weighs in at 605g with a tape covered fuselage- we haven't decided on whether to tape the wing or not yet. I've seen the Pico Cub ROG in about six-eight feet and climb very quickly into a brisk wind with the gearbox, very impressive. So there is probably something simple amiss with your power train somewhere. I'm sure you will be able to locate and cure the problem. Firstly are you sure the prop is rotating in the right direction?- you will have needed to reverse the connections to the motor (black lead to the positive) if using the gearbox. Is the main gear slipping at all on the main shaft? - there is a little grub screw to retain it. You say you batteries are fully charged- is this the first time they have been charged- maybe they need to come up to spec? Any of the above or perhaps that your ESC is not giving you the full throttle range are possible explanations for the reduced power you are seeing. What make and model of speedo are you using- does it have a little screw to adjust the motor maximum RPM or a particular start up sequence (TX on-throttle closed-RX on or similar) to initalise properly? Good luck with the Pico Cub cheers Brian

Jan 06, 2001, 08:09 PM	#6
Fred Bronk Our Daddy and Heli Junkie Join Date: Aug 1999 Location: In Heli Wonderland Posts: 22,535	Are you sure 6 cells are enough, what is the motor? Is the prop on the correct way, IE facing forward?

Jan 06, 2001, 08:21 PM	#7
hoppy Registered User Join Date: Oct 2000 Location: Key West Posts: 13,109	That amperage is better. Well, if the prop is on correct and is blowing the air back, then lets look at the balance. How much balance weight did you add? Where did you add it? When it takes off, does it tend to go straight ahead or rise sharply by itself? Same question for the hand launch? You should let the plane fly level for say 100-150' before giving it much up elevator so it can gain flying speed. If it is going up by itself, you have either..(1) an up elevator at neutral stick setting, or (2) the plane is tail heavy. Are you taking off at full throttle? If you have a small scale, ie ozs, attach it to the tail and fire it up. Should read 7-8 oz (196+g). More later.. Hoppy

Jan 07, 2001, 12:44 PM	#8
jerrysimon Crashing IS Flying Join Date: Jan 2001 Location: Cambridge, England Posts: 1,403	Hey thankyou very much for your replies and sugestions. Anyway fixed it for the third time. Fourth flight today. Waited until late afternoon when everyone had gone home from the park and the wind was "almost" still. I was definately putting on too much elevator. This time is ROG and stayed aloft for about 30 second but gained no more than 3-4 feet in height before coming down. Power is DEFINATELY the problem. The guy in the shop sold me 6 * AA (7.2v 700mAh) Nicads which I think are the ones for a Tx not the short stubby AE/AR. The ones he gave me also have a label that says charge @70mA for 14-16hrs. Anyway I have now ordered some Sanyo 6 cell 7.2V 600mAh AE ones which will arrive tommorow. At least then the model will be exactly as specified on the box. Just a thought maybe I should have ordered the 7 cell ones, although I was worried that they would burn out the motor faster. Jerry

Jan 07, 2001, 02:55 PM	#9
jerrysimon Crashing IS Flying Join Date: Jan 2001 Location: Cambridge, England Posts: 1,403	Yes it freezing here! My daughter came out with me to catch it all on video. They (the rest of the family) then come back and have a hoot watching me smash it up :-( As you say it's good to come back with it still in one piece. Anyway I will update you all tommorow when I get the new batteries. Once again thanks for all the advice. It great to have a resource like this to bounce problems off. Jerry

Jan 07, 2001, 03:48 PM	#10
hoppy Registered User Join Date: Oct 2000 Location: Key West Posts: 13,109	I definitely think the temperature may be a factor. Are the batteries warm when you start? My batteries are NiMH and really lose zip when the temp is low...low being 45 here in Florida. It took one more cell to bring them back to where they were when it was warm. Hoppy

Jan 07, 2001, 06:10 PM	#11
jerrysimon Crashing IS Flying Join Date: Jan 2001 Location: Cambridge, England Posts: 1,403	Hoppy, Just noticed reading through the blurb on my Jeti 180 ESC, it has a brake on it ? It says this can be turned off by plugging in the jumper. At the moment the jumper is not fitted i.e the brake is enabled ? Jerry

Jan 07, 2001, 07:17 PM	#12
hoppy Registered User Join Date: Oct 2000 Location: Key West Posts: 13,109	Jumper off-break on Jumper on - Break off It was recommended to me by US Jeti distributer to put the jumper on - break off. Hoppy ps I noticed during bench tests that my motor puts out significantly more power when batteries are at 60deg as opposed to 40deg. About 15% under static conditions. The plane I've been flying is marginally powered and during this cold spell it just doesn't want to stay in the air...very similar to what you have described. Adding 1 cell has made it flyable again.

Jan 07, 2001, 07:24 PM	#13
Travis Master of disaster Join Date: May 2000 Location: Northern Virginia Posts: 707	jerry, the "brake" you refer to simply means that when the BEC cuts the motor at low voltage, the prop will not windmill during the glide. (a windmilling prop is a big air- brake and will make a model drop like a rock when the power is off). the brake is also nesesary when using a folding prop. Keep those batteries in your pocket untill your ready to take-off. If you have any battery cooling vents block them off untill it gets warm outside.

Jan 08, 2001, 01:02 AM	#14
Mark Wood characters welcome Join Date: Feb 2000 Location: San Diego, Calif. Posts: 18,146	Sure sounds like a voltage problem. What's the voltage rating on your motor? Nobody has asked that one yet. Running up to 8 cells on a 6 volt motor or 10 on a 7.2 volt one is acceptable. We actually got a friend's Hobbico SkyRunner to fly simply by adding a sixth cell to the useless 5 cell pack that was supplied with the plane. MORE POWER! (grunt grunt grunt) mw

Jan 08, 2001, 01:06 AM	#15
leccyflyer Get One Up! Join Date: Sep 2000 Location: Cheshire, England Posts: 9,302	Jerry The instructions with our Pico Cub specify 6x600mah AA batteries- not the dumpy 600AEs you refer to- though I suspect either would do. You could easily add an extra cell (or two) as well - especially if your model was supplied with a 7.2v Permax rather than the 6v version. Did you buy this as a made-up pack or did you make the pack up yourself? What are you using for a charger?