RE: Hobbico Electristar Select EP Trainer RTF (Full Version)

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mark IX -> RE: Hobbico Electristar Select EP Trainer RTF (6/2/2007 8:55 PM)

Hi Greg, I was reviewing your article "Glow Conversions Made easy" and I have a couple of questions. First when you calculated the power class of the motor in Watts, you used the max burst current of the motor. Why didn't you use max continuous current instead? The current that was calculated was 432w. Further on in the article you combine the motor (AXi2820/12) with either the 10 cell NiMH pack or 3 cell Lithium pack, a 40 amp ESC, and an APC 13x10 e-prop, the resulting power system will provide 385 watts at 37 amps. How did you get from 432 watts to 385 watts?

Thanx, Mark



mark IX -> RE: Hobbico Electristar Select EP Trainer RTF (6/2/2007 9:01 PM)

Greg, by the way I am considering converting my 1/5 scale Spitfire to electric. It has a ws of 83" and weighs around 15-18 lbs when done. I was looking at the AXi 5330/24 motor with a CC Pheonix HV 85A ESC and I have not decided on the batteries yet. Probably an 8s or 10 s LiPo with 3500 to 4000 maH rating. What do you think am I in the right ball park?

Thanx, Mark



cwharper -> RE: Hobbico Electristar Select EP Trainer RTF (6/3/2007 7:35 PM)

Well, I have electrified the electristar with lights. With red, green, and white leds with some resistors, a 1 cell lipo battery, and an electronic rc switch it adds a bit of character to it.

http://hdpc.homeip.net/webdownload/electristarwithlights001.jpg
http://hdpc.homeip.net/webdownload/electristarwithlights002.jpg
http://hdpc.homeip.net/webdownload/electristarwithlights003.jpg
http://hdpc.homeip.net/webdownload/electristarwithlights004.jpg
http://hdpc.homeip.net/webdownload/electristarwithlights005.jpg
http://hdpc.homeip.net/webdownload/electristarwithlights006.jpg

I used 26 ga magnet wire for a positive and negative run along each wing half joined in the middle with a y-harness to connect to the battery. It took a lot of patience and soldering.

The white leds are 50 degree 7000mcd and they do a so-so job of lighting up the ground about 5 five in front of the plane in total darkness. Only after I had completed the lights did I find the leds available from ebay and now wish I had the 10mm 140,000 mcd white leds. I bet those would light things up.



screendoor -> RE: Hobbico Electristar Select EP Trainer RTF (6/3/2007 10:31 PM)

I just bought and assembled an Electristar Select RTF. I'm pretty new to rc planes, having fooled around with an Aerobird and now upgrading to this. Really looking forward to getting rolling with this new plane. Unfortunately, though, I think I'm having battery issues. I bought this at a retail store. The only batteries they had in stock at the store were the Nitro Power SuperBoost 7 cell Ni-Cd. The guy at the store said this wasn't exactly optimal, but that these would work. My plan was to ultimately use these as backups, and get a set of NiMH batteries as soon as I could. But when I power everything up with these Ni-Cds fully charged (at least I think they're fully charged) and installed in the plane, the prop will run for a minute or two then just stop. None of the control surfaces work at all. I tested this only on the ground -- not in the air, obviously. I recharged the batteries, and exactly the same thing happened again. I looked online, and found out that these batteries are only 1500mAh, and Hobbico recommends 3,000 mAh. Have I been duped by the guy at the store? Meaning, are the lower powered batteries the source of the issues I appear to be having?

Thanks in advance, from a newbie, for any help that anyone can offer.



cwharper -> RE: Hobbico Electristar Select EP Trainer RTF (6/4/2007 12:31 AM)

How are you connecting the packs to the esc? The esc has two deans ultra connectors and your packs I believe have the old Tamiya style connector. The best thing to have done is to change the connector on the packs to female deans ultra connectors. But then the packs probably couldn't be returned to the retail store. You must have the packs connected to the esc because you said the motor does run. You also said none of the control surfaces work. Aside from assuring the servo linkages are physically attached to the control surfaces, the next thing to do is charge the 4 cell nicd pack that powers the receiver. It's either a green or red pack next to the receiver. While you're charging that you might as well hook up the transmitter battery too. Just use the wall wart charger that came with the transmitter. There is no BEC in this plane so if this pack is dead that could be the source of your intermittent operation. The last thing to consider is that your 1500mah packs may not have enough capacity to run the motor at full throttle before the voltage drops below what the esc can tolerate and so the esc shuts down. The stock setup at full throttle draws around 28 amps. While it's not advisable to let the motor run while on the ground, try only running the motor at half throttle or slightly less and see if that results in a longer runtime. There have been cases of faulty transmitters causing interference symptoms but you would have a difficult time proving that until you get the recommended batteries. One last check, you do have two 7 cell packs connected in series don't you for a total of 14 cells?



screendoor -> RE: Hobbico Electristar Select EP Trainer RTF (6/4/2007 1:17 AM)

Thanks so much for such a complete and quick response. Here's info answering the questions you brought up.

1) Yes, I cut off the Tamiya-style connectors from the battery packs, and soldered female Deans connectors onto them instead (and I also had to create a male Deans adapter for the charger that I also got from the store). Frankly, if the packs won't work, I'm pretty optimistic that I'll still be able to get my money back, because I was pretty much told they would.

2) The servo linkages are connected. BUT I DIDN'T CHARGE THE 4 CELL NICD PACK THAT POWERS THE RECEIVER. I didn't realize there's no BEC in this plane. But could this be the source the source of all my problems? The receiver battery had enough juice to receive the signal necessary to power the engine, at least for a little while. Why wouldn't it have enough juice to receive the signal to power the control surfaces?

3) I actually only ever powered it to about half throttle.

4) Yes, I have two seven cell batteries connected. I can only assume that they're "in series", in that I connected them in what appears to be the only way they can be connected. Maybe I'm missing something here?

Thanks again for your help. I'm off to charge the receive battery. Like I said above, could that be the cause of all my problems here?



cwharper -> RE: Hobbico Electristar Select EP Trainer RTF (6/4/2007 2:23 AM)

It's entirely possible the receiver pack had borderline voltage and just enough juice to power up the receiver and allow you to operate the motor esc but then voltage dropping when attempting to operate a servo and the receiver cutting out. Put a charge on the receiver pack and let's see what happens.



spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (6/4/2007 9:44 AM)

screendoor, cwharper has been doing some neat things with his electristar and has a lot of good advice.

You have to remember that the batteries have 3 important parameters; voltage, capacity, and current delivery or C rating (how much current can be sourced all at once). I believe the recommended NiMH batteries are 3200mAH batteries at 20C. This means they can source 20X3.2A or 64 Amps. If your batteries are 1500mAH at 20C, that would be 30 Amps and may not be enough poop to power the ESC and motor. Furthermore, it is possible that you batteries are not 20C. They are typically more expensive. You'll see a lot of batteries at 10C or 13C. Either way, this could explain why you can't run full throttle or for very long. You need to have the voltage to push the current (7 seems fine with two in series), you need to have the capacity, and then the source capability to get the capacity as fast as you need it.

I have two 2-cell Lipo batteries. Connected in series gives me 14.8 volts (or 16.8 charged). Our motor needs between 10-20 volts. They are 4200mAh batteries but 15C (1C being 4200) So, 4200X15=63A. So, you can use a lower C rating if your capacity is higher. I love the LiPo batteries. They shave a lb off the weight, but were 4 times the cost.

So, it you want to stay with the NiMH, go back to the dealer and get the ones recommended in the manual, the 3200s at 20C.

You'll notice that the BEC (battery eliminator circuit) 3-wire harness coming from the ESC to the receiver has one wire lifted up. That disables the BEC. The manufacturer thinks that the motor needs all of the current, so you need to charge the 4-cell NiMH pack in the plane and connect it to "battery" on the receiver. That powers the servos. The 600mAh batteries give you 3-4 flights before you need to check the voltage (at 4.8V you better be recharging, I think). I replaced my 600 with a 1500. I also replaced my xmitter 600mAh battery with a 2500mAh pack. Radio doesn't go dead so fast.

A caution. You will be powering up the ESC when connecting the motor batteries and arming with throttle position. You will also be switching on (switch on the side of the bird) the servo/receiver battery. After flying, you may shut off the receiver battery. If you haven't disconnected the motor battery, switching back on the receiver leaves you with a live motor. You don't have to rearm the ESC. So, take caution to always disconnect the motor battery first thing.

And finally, the manual says that the ESC cuts power to the motor when the batteries reach something like 70% of their charge. Thus, if you connect a partially charged battery, the ESC will think that that is its max voltage. So, connect a fully charged, proper capacity battery and she'll fly like a champ. Know how long your motor runs with a mixture of full and half throttle. Then, time your flights and land with charge to spare (dead sticks are hard and don't leave room for a go-around).



spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (6/4/2007 9:54 AM)

cwharper, I like your lites. Does this allow you to fly at night, or just at dusk?

I see the APC prop. It that the 13x6.5E?

I haven't flown my 'star in a while. I've been flying an Extra 260 3D foamie. It has done wonders for my reflexes. It's nice as I can fly it at the park by my house and don't have to go to the port. I keep getting in trouble when flying at dusk and can't tell which side's up. That's why the lights on your 'star look fun. I have been flying under the lights at a ball diamond. I use outfield at the little leaguers can't hit out there. I also build a mini super sportster with brushless. Sweet.

I'm able to handle these other planes because of the electristar. It is such a good trainer, and will accept mods to increase performance.



cwharper -> RE: Hobbico Electristar Select EP Trainer RTF (6/4/2007 2:22 PM)

Spacestout, I'm hoping the lights will allow me to fly at dusk but haven't had a chance to try it yet. It's been very windy lately and work at the hospital has been crazy. I also took some pictures in total darkness but they didn't do it justice. The red and green leds which are pointed at the rear not only light up a bit of the wing but also the fuselage and the white wall of the house in the background. The leds are so bright they will create a blind spot in your eye that won't go away anytime soon. The white leds seem like they are bright but don't really throw enough useful light to see the runway. I may yet decide to change the white leds to the 10mm's I found on ebay (more soldering).

Yup, you've identified the APC 13x6.5E and one other thing I've done that's not in the pictures is change the wheels to 3.5" dave brown lites. It seems to roll better with these and gives me more ground clearnance.

I've been eyeing another plane too and it sounds like a 3D foamie would be a cheap way to go to tune up my reflexes before I plunge into something bigger, like a P51D from Hangar 9, electrifed with brushless of course.



spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (6/5/2007 9:24 AM)

According to the tables for our motor (Electrifly Rimfire 42-50-600), you may be able to put an even larger prop. The current drops, surprisingly. Taller wheels would allow this.

It is really hard to beat the E-flite Extra 260 3D foamie. I went with the Park 370, 10x3.8 prop, 800mAh battery and AR6000 receiver. Came in a little heavy. My friend used the lighter park 300. He can land slower. The foamie pro at our port flies the Tensor 4D biplane. Incredible what he can do. I'd recommend either of them. They really fly differently than wings with lift, but they react so quickly and do all the aerobatics that they really train you.



screendoor -> RE: Hobbico Electristar Select EP Trainer RTF (6/6/2007 12:44 PM)

Thanks, Spacestout and CWHarper for all your advice. Here's the update. The good, and unsurprising, news is that the control surfaces actually worked after charging the Rx. Amazing! :-) The bad news is that I still don't have enough juice to fly. After fully charging the 1500mAh batteries, I could taxi for about 100 ft or so, but didn't have enough power to take off. After about 90 seconds, I didn't even have enough power to taxi. The batteries died completely after about another minute. So here are some follow up questions:

1) I'm using a peak charger, sold to me by the guy at the store for use with these batteries. But I now see that the batteries say "Do not use with a one hour or less charger." Has this killed my batteries?

2) I charged the batteries once with the charger set to 2 amps (again per the advice of the guy at the store), but the batteries are only 1500mAh. Has this killed my batteries?

3) I don't see the C rating of the batteries listed, either on them or online, but from Spacesout's posting I gather that even if the batteries are fine, they may not have enough power to fly this plane because of a low C rating. Any advice on how to find the C rating?

4) A guy at the field told me that these batteries should work if I go through the charge/discharge cycle about 6 times, meaning they'll take a much more powerful charge after about 6 cycles. Really? The difference will be so great after 6 cycles that I'll go from only taxiing for a minute or so to flying for 8 minutes? I find that hard to believe.

As always, any help you can provide is much appreciated.



cwharper -> RE: Hobbico Electristar Select EP Trainer RTF (6/6/2007 2:22 PM)

screendoor, I would attempt to return those batteries as they aren't going to work as advertised. If the lhs still doesn't have the recommended batteries then order them from towerhobbies.com Do a search in these forums for "towerhobbies ad number" and find one that will either get you free shipping or $10 off Also search google for the ad numbers. I've had luck with some I've found. You're better off anyway with larger capacity batteries.

search towerhobbies for "electrifly 3000" If you can spend $125 or more I've got a discount code that will work.



jbang -> RE: Hobbico Electristar Select EP Trainer RTF (6/6/2007 11:37 PM)

Can anyone recommend a good float match for the electristar?



screendoor -> RE: Hobbico Electristar Select EP Trainer RTF (6/7/2007 2:42 AM)

Thanks so much for the insight, and for the offer of discount possibilities. that's very much appreciated. The LHS has agreed to take the batteries back, so I should be ok. But I am still curious about why these didn't work. I understand why these wouldn't last very long, but why wouldn't they have enough power for a short flight? Seems to me that either the C rating is low, per spacesout's post, or I fried them when I charged them at 2 Amps.

Steeper learning curve here than I expected. Can you recommend a good online battery tutorial? I've looked at a few, but the ones I've seen haven't been too helpful.

Thanks again .



rick88ss -> RE: Hobbico Electristar Select EP Trainer RTF (6/7/2007 6:32 AM)

Look here

http://www.batteryuniversity.com/partone-16.htm



spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (6/8/2007 1:36 AM)

Do you ever wonder why lights don't work in a brownout? You need a certain amount of electromotive force (EMF) to turn a motor, or in the case of electronics, to exceed thresholds and turn on transistors.

Just like a little kid trying to push a heavy cart. I've seen a few people show up at the field with their new planes and they won't arm or don't have the power to take off. Often, they are trying to fly with 2 cell (LiPo) batteries and 7.4V when they should have 3 cells and 11.1V.

I don't know a lot about NiMH batteries as I fly LiPos. So I don't know if they show a C rating. I'm sure there are some fancy machines for analyzing batteries. But I find it indispensable to have a Watt meter. I put Deans connectors on mine, and then put it inline between the motor battery and ESC to observe voltage, current, watts, and mAh's used. For example, my 4 cell LiPo in the electristar. Each cell has a nominal voltage of 3.7V, and when charged is 4.2V. That is 14.8V nominal and 16.8 charged for the pack. I observe things with throttle off, and then at full power. I can read the current. This is useful in knowing if the prop selection is proper so I don't draw too much current and burn things up. I can watch the voltage drop over the first minute, then stabilize (as does the current) for 10 minutes, then rapidly fall off as the battery approaches 14.8V, and then have the ESC cut power to the engine at about 12V. This tells me my setup is working correctly. If you connected such a setup you could see if you are getting your 18V (or whatever NiMHs give), and if you get your 28A at full throttle, and what happens over time. If you find you only get 10A, something is wrong. Low voltage? Batteries unable to deliver 64A at once? Motor with a short?

cwharper is right. Get the NiMH's recommended with the kit (or go LiPo, but the same principles of having enough A applies). And get a Watt Meter. And, check your radio battery pack before you fly. If you are approaching 4.8 V, don't fly. The 600mAH pack which comes with the 'star gives 3-4 flights. I swapped mine out with a 1500mAH pack. I put 2500mAh packs in my transmitters (tired of them running out of juice before the day is over).

My buddy in the battery business (racedayrc.com) says you can charge a NiMH pack at 1/2 their rated capacity. So, a 1500mAh battery at 750. Wall Wart chargers will typically charge at 100-150mAh. Peak charging isn't a bad thing. It tops off your battery so you get the extra burst for takeoff and climb.



rick88ss -> RE: Hobbico Electristar Select EP Trainer RTF (6/8/2007 5:17 AM)

quote:

ORIGINAL: spacestout
If you are approaching 4.8 V, don't fly. The 600mAH pack which comes with the 'star gives 3-4 flights. I swapped mine out with a 1500mAH pack. I put 2500mAh packs in my transmitters (tired of them running out of juice before the day is over).



Where did you get the batteries for the Tx and Rx and how much $ ? Does it really matter what brand when picking those batteries? I'd also like to upgrade my Tx and Rx batteries before I go flying and use the stock ones for back-up.

I just ordered two TrueRC.net 10C 14.8V 4S1P 4000mAh LiPos. I plan on running them in parallel for long flight times or various short flights without having to recharge. I can use one 14.8V 4S1P alone or put both in the plane wired in parallel for 14.8V 8000mAh. Will these batteries work with their 40amp continuous/60 amp burst each or should I go with two 10C 7.4V 2S2P 8000mAh wired in series w/80A Continuous/120A Max burst ?


They cost $75 each and have a good warranty. Has anybody used these batteries? Does the ESC automatically turn off the engine when they reach the required minimum voltage?



fecalasu -> RE: Hobbico Electristar Select EP Trainer RTF (6/29/2007 8:28 PM)

For those who like videos here are my two cents.



spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (6/30/2007 7:42 AM)

Sorry for the delay. I got the Rx battery at my LHS. Just a JR 1500mAh pack. I think I went to http://batteriesamerica.com/newpage8.htm for the transmitter pack. On this page you can find "transmitter packs for radios". The Futaba for the electristar takes a flat pack of 8 at 9.6V. The DX6 takes the square pack of 8. Get the brand of battery with the connector needed in the mAh needed.

Give us some feedback on your 10C batteries. Two packs in parallel seems like a lot of weight and a lot of real estate inside the plane. I guess you should be able to fit them, but balancing may be a challenge.

I know the original recommendation was for over 60A continuous. I wonder why when the motor draws about 28 A. I've got mine at 35A with the bigger prop. So, depends on props.

I'm not a battery expert. I keep learning. Tonight I had two 3s cells, an Apogee 2500 mAh 20C, and a Thunder Power extreme 2070 mAh 25C. They should both source 50 A continuous. However, the TP is rated at 105A burst. I ran them both on my Super Sportster with an Axi 2820/10 motor (42A rating for 60s) and Silver Series 45A ESC. The watt meter showed 400W with the thunder power, but only 320 with the Apogee. I got a little less current with the latter, and less voltage, so the wattage was less.

So, you may discover something fun like that. As long as they power you for as long as you want and with the performance you want, great.

Read the manual on the ESC. I believe it does turn off the motor at 67% of initial voltage. Can't remember if it is a hard shutoff (hit cutoff and the motor stops) or soft, where you notice a power reduction before total cutoff. The key to remember is to have fully charged batteries when you connect up to fly. The ESC makes its decision on the voltage cutoff point based on this charge. Start with a low voltage and you'll find your batteries discharging rapidly to a lower than desired voltage (once below 3.3V/cell voltage drops rapidly). So, you risk not having enough power to return to base and damaging the batteries.

Let us know.



spacestout -> RE: Hobbico Electristar Select EP Trainer RTF (6/30/2007 7:47 AM)

I liked the video very much. I work on the unmanned air vehicles such as the globalhawk and predator so I'm used to a little better video quality (he he). But that is really cool. I may have to try it on my plane. The electristar is such a good, stable mount for such things. They should have named it the Sherpa. Packs a lot.

A highway patrolman at our club flies (flew) an $8k helicopter (with turbine engine) and a camera setup to he could loiter and film. Too bad he crashed. I told him to forget stakeouts and film celebrity weddings.



echoguydd -> RE: Hobbico Electristar Select EP Trainer RTF (7/9/2007 9:20 PM)

Hello all. I am a new member with a question concerning my brand new electistar. The slot that the horizontal stabilizer slides into is a little bit too wide. I mounted the stab and also followed the instructions reguarding putting a few drops of CA into the screw holes. My problem appears to be that there is a gap approximately 3/32" that allows the stab to wobble. I have tightened the scews as far as I am willing without stripping the holes. Has anyone else had this issue. I contacted Hobbico and they haven't heard of this. I guess I am going to epoxy a thin piece of light ply to snug up the fit. Any suggestions would be appreciated.



cwharper -> RE: Hobbico Electristar Select EP Trainer RTF (7/10/2007 3:03 AM)

I just CA'd the whole stab into the fuse and not just in the screw holes. Mine was a little wobbly too with just CA in the screw holes so I glued the whole thing in there permanently. I would suggest that if the gap you are talking about can be closed by holding pressure with your hand, then apply CA in the gap with the stab installed and hold pressure until it sticks or use some accelerator for a near instant stick. If you add any wood back there it might be enough to make it tail heavy.



echoguydd -> RE: Hobbico Electristar Select EP Trainer RTF (7/10/2007 5:31 PM)

Thanks for the insight. Last night I purchased some larger diameter sheet metal screws and installed them after filling the original holes with thick CA. I found that if I squeezed the slot together and tightened the screws the wobble is greatly diminished. I plan on removing the monokote from the stab and gluing it permanently with 30 min epoxy.

How do you like your plane? Are you using the NiMH or Li polys? What are your average flight times?



Greg Covey -> RE: Hobbico Electristar Select EP Trainer RTF (7/11/2007 1:07 AM)

I think cwharper has a good suggestion. I didn't see any comments about the vertical stabilizer in my review so it may that the production run models had a larger gap. Typically, you can squeeze this type of mounting scheme like a clamp as you tighten the screws.

Good luck!



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