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Tweet
09-12-2005, 04:31 AM
What are you guys using for giant scale UBECs? So far I have been using the Ultimate UBEC sold through Hobby Lobby. It says it is good for 10 servos and 3 Amps continuous or 5 Amps peak. Haven't been able to find the current rating for the various Hitec servos I am using. I would think I would be okay using one of these for the Funtana 90 I am putting together (5 Hitec HS-5625s) but wonder about the larger 28% Wild Hare Extra (4 Hitec HS-5945s and 1 JR 8611).

Any thoughts?

Greg Covey
09-12-2005, 01:00 PM
To supply current to the hi-power servos on my 33% Edge 540, I used a new product from FMA Direct. It is called the VRL12 "Power Force" regulator. It works on a 2s, 3s, or 4s Lithium pack as well as 5-12 NiCd cells. The 6v output can run up to 12 high-torque servos at once and is meant for giant scale applications. Finally, the regulator unit is equipped with an externally mounted ON/OFF switch that is failsafe, meaning, if it fails, the unit comes ON, not OFF.

The linear regulation produces no radio interference (RFI).

Here are some features of the VRLI2:
Designed for high current servos and receiver in R/C aircraft
Ideal for aircraft using dual radio systems
Accepts input from 2s to 4s LiPo or 5-12 cell NiCd/NiMH
Switch selectable 5v/6v output at 10amps continuous
0.15v dropout when voltage goes below 5v/6v setting
Three Status LEDs provide battery condition information
Failsafe On/Off switch - fails to ON mode
Will not drain battery when switch is Off

Tweet
09-12-2005, 01:50 PM
Hi Greg,

Yes, I looked up your conversion and saw this product. This would mean I would have to add an additional battery for the servos and receiver.

Do you recommend this practice for the large scale projects?

What size battery did you use? I'd like to fly all day (okay realistically perhaps 4 15-minute flights) without having to recharge the servo/receiver battery.

I don't think I would bother for my Funtana 90 (a lot of people are using the Ultimate UBEC for this scale of project), but would consider it for the larger Wild Hare conversion if it provides some advantage.

Thanks.

Dave

Mike Parsons
09-12-2005, 09:17 PM
Jeff @ Koolflightsystems makes a redundant 6v UBEC system (KFS makes the UBEC's that HL supplys). This is what I use in my 87" Yak.

Tweet
09-12-2005, 09:45 PM
Mike,

When you say redundant, were you using two? Okay, just checked your thread and saw you were using two.

Wouldn't use two on the Funtana, but would consider it on the Extra. But where do you stop? Then perhaps I should use two receivers, etc. I tend to think the UBEC would be one of the most reliable components on the entire airplane. Any reasons for using the two UBECs?

I have been using these on all my other airplanes without any problems so far.

Mike Parsons
09-12-2005, 10:05 PM
Mike,

When you say redundant, were you using two? Okay, just checked your thread and saw you were using two.

Wouldn't use two on the Funtana, but would consider it on the Extra. But where do you stop? Then perhaps I should use two receivers, etc. I tend to think the UBEC would be one of the most reliable components on the entire airplane. Any reasons for using the two UBECs?

I have been using these on all my other airplanes without any problems so far.

My main reason is I am using two Motors, Two ESC's, Two sets of packs. Each UBEC is tied off of an 8S. If I have one pack go poof, I still have power to get it down. It is just another safe guard and a bit of security. Of course if one pack goes poof, I may not have much to bring down :).
Everything electronic will fail at one point or another. If I were using a single motor, with a single ESC, I wouldnt worry about it and would simply use one. I agree with you though, in that where does it end? I guess where one feels comfortable. If I decide to convert a 150CC craft, I would go the whole route of dual RX as well.

Greg Covey
09-14-2005, 09:34 PM
Dave,

I'm not sure what you mean. I don't have an additional battery in my 33% Edge 540 for the regulator.

Tweet
09-14-2005, 09:44 PM
Greg,

When I look at the specification for the regulator is says you can use 2-4 lipoly cells. Since you were using two 5S Lipolys in series I assumed you must have had another battery on board.

What did you end up doing?

Dave

Greg Covey
09-15-2005, 12:39 AM
I'm not sure where you read that but I have a two-part article on RCU about my 33% Hangar 9 Edge 540 conversion.

My Lithium setup is a 10s3p configuration of Kokam 2.1AH (20C) cells. It is split into a 6s3p and 4s3p subpack for this purpose.

Tweet
09-15-2005, 02:42 AM
Greg,

My bad, I misread the article (have read both 1 & 2 extensively). Well, I have two TP 5S4P batteries already for my Wild Hare so I will have to go with another solution.

Greg Covey
09-15-2005, 12:56 PM
FMA does have three combo packages for giant-scale gas planes using 2-cell Lithium packs and various size regulators. This may work fine for a large electric as well and provide the safety of not being part of your motor power system.

You may be interested in our KOK3270 Gas Flight Pack Special 3 (Part Number: LI-POGFP3)

It uses a lighter KOK3270-2S-DNS Lithium Polymer Pack with the new Power Force Voltage Regulator (PN:VRLI2) and normally sells for $135. I can get the weight of this package, if you like.

PM me if you are interested and we can work something out. I'm off to the NEAT Fair in an hour but will be back on Monday.

flashover
09-16-2005, 03:42 AM
Greg,what kind of flight times are you getting with that setup,both 3d and normal flight modes.

Tweet
09-17-2005, 02:12 AM
Also, how many flights to you have on the AXI motor in the Edge? Seems like the motor was the weakest link. I think you said you were flying with the 21x14 (3,000 watts plus WOT). That should really be giving the AXI a workout.

Greg Covey
09-21-2005, 09:51 PM
flashover,

I'm not sure what setup you are refering to.

Tweet,

I probably have between 20 and 25 flights. It flew at the NEAT Fair last weekend in the Friday and Saturday noontime demos. Remember that the burst power is 3500 watts but the plane flies fine at 1/3 throttle. At 2000 watts, the motor is around 87% efficient so little heat develops in the open cowl.

The key is too keep your parts cool.

We'll see if some new motors show up on the U.S. market this Winter. We already know they exist in Europe. :)

flashover
09-23-2005, 04:20 AM
Greg, all too often I hear pilots of electric planes speak of 6 minute flight times and for me that's not long enough.And as we all know it takes more power to fly 3d or any aerobatics than to fly circuits around the field.

Tweet
09-23-2005, 12:53 PM
Greg, all too often I hear pilots of electric planes speak of 6 minute flight times and for me that's not long enough.And as we all know it takes more power to fly 3d or any aerobatics than to fly circuits around the field.

I'll get 15 minute aerobatic flight times from my 5S4P Lipolys on my 28% Wild Hare Extra. On my 5S4P Kadet Senior I get 30 minute flights (more than I can stand) and equivalent performance to the Saito .91 powered Kadets at my field.

Read some of the threads, not many people are putting together airplanes that can barely climb and maintain altitude for 6 minutes these days.

Greg Covey
09-25-2005, 12:31 AM
flashover,

Ok, I'm still not sure what your original question about flight times was for. My Edge 540 perhaps?

If you need a setup for a particular plane...ask away.

Matt Kirsch
09-25-2005, 12:46 AM
flashover,

There are no laws restricting flight times or performance. All it takes is the right planning, and that's why guys like Greg, Mike, anb I are around to help.

For example, Greg's 1/3 scale Edge is only aerobatic, not 3D. It's also 4-5lbs lighter than the standard 3D setup, so there's room to add more motor and battery capacity for more powerful, longer flights. He could easily add a second complete power system identical to the one he has in there now, couple the two motors to a common propeller (ala Mike Parsons's Yak), and turn the plane into a 6 KiloWatt 3D Monster. I'm still working on trying to get him to do it :)

flashover
09-25-2005, 01:59 AM
Tweet:I as well have some electric planes that fly for extended flight times.But I'm curious as to how long a 33% like Greggs flys on essentially 6 ah worth of power,that just doesn't seem like much power for such a large plane.I keep seeing people talk about these conversions but what piques my curiosity is no one ever mentions flight times.I am flying a gp su 31 extreme 3d on a tp 3s 2100 it weighs about 25 oz. auw. and I'm seeing flight times of about 15 min. with no 3d flight( I'm not that good yet). Otherwise my plane sees very few straight lines (always inverted, knife edge ,loops etc).
Actually,an evening flying is usually ended by flying our Gws tiger moth on a hacker brushless and 12oo mah etec's that will occasionally fly for upwards of an hour ( we pass the tx back and forth) a relaxing way to end the day.

Matt; I'm sorry you must have posted while I was typing(yes I'm slow).I thought all the bigger planes had the huge control surfaces to be able to 3d.Sooooo I would like to know how long generally are his flight times on one charge of his battery packs.

Greg:Yes,I was refering to your 33% Edge 540.My flying buddy(daughter) and I really like not having to clean the plane before we go home.Right now our biggest plane is a gp easy sport.we,re considering something bigger for our next plane.So I'm doing research.It may well be electric.

Greg Covey
09-25-2005, 10:54 PM
The theme of my 33% Edge 540 was lower cost, hence the "1/3 Scale at 1/3 Cost" jingle. For $500, you get a highly aerobatic giant-scale e-conversion but not really 3D capable (at least hovering) but you can harrier and knife-edge across the field. In my Part 2 write-up, I talk about a 30-cell GP3300 NiMH pack giving you about 7 minute flights and my 6AH Lithium pack about 15 minute flights.

red_z06
09-26-2005, 01:18 PM
Flashover:

If you are interested, my H9 Extra 260 is fully 3d Capable and it flies for 11min on Kokam 9s4p (8000mah) pack with Axi 5330/28 and apc 22x10e prop. If you were at NEAT, you probably saw my plane there.

flashover
09-26-2005, 06:00 PM
Thanks guys, that is what I'm after.I'm really amazed that 6-8 AH will fly a giant scale plane for 15 min.This is looking more feasible all the time.

Darrell B.
09-27-2005, 05:23 PM
I have a Top-Flite Giant P-51 ARF that I'm getting ready to maiden, as soon as the weather permits, with a 9 AH flight pack. I am anticipating a total of 20 minutes of flight times, with better than scale aerobatic performance.

By the way, to stay on topic, I chose to use a 5cell 2500 mAh flight pack. I placed it in a very easy to reach location, and built two, so that I could change them out during the day if I needed.

Darrell

Electrick
10-12-2005, 01:09 AM
Is there some fundamental reason why guys still go with UBEC's on large aircraft instead of a separate smallish, dedicated LiPo pack (say, a 2100 mAH) and a regulator? You could easily put in a 2S2P and fly all day (probably all weekend) easily on one charge.

Seems like one less worry (vs. a BEC) if a motor pack poofs inflight with a BEC tied to it. But of course Murphy's law would just poof the rx pack inflight then, right? :D

Frankly, with the weights of the average quarter scale and above airframes, a big 6v NiMH pack and regulator makes the most sense to me, insofar as reliability goes. A few more ounces is peanuts on a 15-20+ lb. airframe.

If they were good enough for glow, then they ought to be good enough for electric, right?

Rick

Mike Parsons
10-12-2005, 01:23 AM
You have some good points Rick. It is just a personal preference with me. They have worked flawlessly for many years and it is one less thing that I have to worry about. Knowing me, it would be the one battery out of 20 that I forget to charge :)

Electrick
10-12-2005, 01:44 AM
I have found that (historically) for me, the forgotten one has always been the transmitter battery. :o

Different strokes for different folks, but I prefer the tradeoff of having to always remember one more thing to charge vs. the (in my mind, greater) odds of poofing a flight pack with the BEC on it. Dual BEC's on split packs do help there, but it's more expense and trouble.

One can/should always carry a spare charged 2S LiPo in the field box (or can even borrow one at the field) if it gets missed on charging the night before.

Everything's a tradeoff. ;)

Rick

jonnyjetprop
10-12-2005, 02:36 AM
Knowing me, it would be the one battery out of 20 that I forget to charge :)

I always get a chuckle out of the I forgot to charge it. At least one guy at the field has a charger that can charge a receiver pack.:D

John

Mike Parsons
10-12-2005, 03:08 AM
Everything's a tradeoff. ;)

Rick
Cant argue with that! :)


I always get a chuckle out of the I forgot to charge it. At least one guy at the field has a charger that can charge a receiver pack.:D

John
I know it would happen to me...I just know it! :D

Tweet
10-12-2005, 03:34 AM
Is there some fundamental reason why guys still go with UBEC's on large aircraft instead of a separate smallish, dedicated LiPo pack (say, a 2100 mAH) and a regulator? You could easily put in a 2S2P and fly all day (probably all weekend) easily on one charge.

Seems like one less worry (vs. a BEC) if a motor pack poofs inflight with a BEC tied to it. But of course Murphy's law would just poof the rx pack inflight then, right? :D

Frankly, with the weights of the average quarter scale and above airframes, a big 6v NiMH pack and regulator makes the most sense to me, insofar as reliability goes. A few more ounces is peanuts on a 15-20+ lb. airframe.

If they were good enough for glow, then they ought to be good enough for electric, right?

Rick

If you go with a 6V NiMh pack you don't even need the regulator.

I am still considering my options for the larger airplanes. I am tempted to go with a battery so I will not have to worry about current draw and because I do have to charge it I keep track of its health over time. The UBEC can put out 3 Amps. I wonder if that is enough with high torque servos or a lot of standard servos. Anyway, for some reason I have got hung up a bit on this issue.

gwright
10-14-2005, 08:40 PM
I use U-becs in everything I fly that's above little parkflyer size. Planes and helis from 3 mini servos up to 6 digitals (large 132 oz/in servos, 1/4 scale planes, not micro's). I trust Ubec's . Since I've been using them,.. I haven't had a single crash due to not charging a reciever battery :) :)
My Cermark 1/4 scale pitts for example, is 14 lbs, has three 9151 digitals plus 4 9650's, running off a single ubec supplied from the 10S4P lipo pack.

Tweet
10-14-2005, 08:43 PM
I am planning to go the UBEC route. Now my only decision is whether to go redundant UBECs. Apparently Kool Flight Systems will put a redundant system together for $90.

drvcrash
10-14-2005, 10:10 PM
Have you ever had radio problems due to the ubec? I have a couple but the one in my H9 twist causes my control surface to vibrate on a range check and if I take it out and just put in a flight battery the pusling vibrations go away.

Tweet
10-14-2005, 10:24 PM
Not that I know of. I did have an extended hit last week at our field and lost an airplane. It had a UBEC in it and a PCM receiver. However, there was never a sign of any type of interference such as you are talking about.

drvcrash
10-14-2005, 10:29 PM
Im gonna try moving it all the way to the front of the plane and move the reciever to the back and see if that make a differnce. I ve been using it for over a year and it just started recently

Tweet
10-16-2005, 12:41 AM
Well, I guess I'll go with the single UBEC even on my 28% Extra. There are several other single points of failure and my guess is something like the UBEC is likely to fail on power up. Probably at least as reliable as the receiver and a single NiMh battery pack.