HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Jun 25, 2003, 10:44 AM
ElektroRC.com - MSH,LAHeli,YGE
Pewaukee, WI, USA
Joined Mar 2002
4,606 Posts
I could just hear Beavis and Buthead making that comment, Tony... (Heh, heh heh)

Gary,

Your skids are on backwards

Have you ever crashed with the LiPos?

I've dumped mine with NiMH and LiPos and I'll say that the logo is not kind to the LiPos at all. The NiMH I just straightened out, the LiPos were ground up by the pinion and the main gear, tabs were pulled off, basically trashed a pack along with the heli.

The longer the pack the more there is to tear up.

The only way I would consider putting LiPos in my 10 again would be if I used 2 thick CF plates on the top and bottom, to protect and support them. I'll pay the weight penalty to know that I won't trash 200$ batteries...

On my RappE, a 4S4P pack fits almost completely in the frame and is very well protected, I've even found room for the 2s4p second pack in the frame to make 6s.

I'll never fly these expensive cells again without protecting them better... Of course if you're never going to crash, you don't have to worry But, jJust a friendly concern/warning!

-P
pwkpete is offline Find More Posts by pwkpete
Last edited by pwkpete; Jun 25, 2003 at 10:55 AM.
Reply With Quote
Sign up now
to remove ads between posts
Old Jun 25, 2003, 11:13 AM
Registered User
Joined Apr 2000
2,300 Posts
Gary,

Did you get a good number for hover power? If so, can you tell me what the weight of the heli was for that power?

Thanks,

Hank
HankF is offline Find More Posts by HankF
Reply With Quote
Old Jun 25, 2003, 12:47 PM
Registered User
GGoodrum's Avatar
South Orange County, CA
Joined Mar 2003
8,094 Posts
Pete --

I've crashed 3-4 times with the E-Techs and once I did have one cell that was destroyed when the pinion ground through the shrink wrap. The nice thing about having a pile of E-Techs around is that it was fairly easy to repair the pack by changing out the one cell. I was usng an aluminum plate for support but it was pretty heavy. Now I'm using carbon rods which probably aren't as "sturdy" in a crash but we'll see. You have gotton me thinking about the pinion and main gear "grinding" problem though. I think I'll add small carbon or aluminum plate to the packs in those areas.

You are right, of course, on the backward skids. You know I thought the antenna used to be on the other side!


Hank --

I will post the hover power and headspeed numbers later this morning. The basic weight without the packs, blades or canopy is right at 64 ounces, or 4 pounds. Without the camera and the two cell Kokum pack, the weight is 59-60 ounces. The TP pack weight is 30 ounces. Same for the 5s6p E-Tech. The 5s5p pack is 26.5 oz. The blades are 7 oz. and the canopy adds another 2 oz.

In the configuration that I will do the hover checks in, that would be 64 + 30 + 7 = 101 ounces. I'll leave the canopy off until I get a baseline on temps. Without a fan and with no air circulating, I'm a little worried about temperature rises so until I can do more testing, I'll just leave it off.

-- Gary
GGoodrum is offline Find More Posts by GGoodrum
Reply With Quote
Old Jun 25, 2003, 03:44 PM
TeamTP,Minicopter,Spartan
misskimo's Avatar
Mississippi 31 years , Now Kotzebue , Alaska 12
Joined Apr 2001
7,454 Posts
huh? I wonder if I can put a half bowl like deal around the pinion so it wont chew a hold in the pack , Im thinking about doing a flip with the logo tonight , getting up the nerve too anyway . what Im thinking about doing is like doing a stall turn but when the heli stops just feed in back stick and - pitch and see , but I will try that with my 12 cells first
Tony
misskimo is offline Find More Posts by misskimo
Reply With Quote
Old Jun 25, 2003, 05:35 PM
ElektroRC.com - MSH,LAHeli,YGE
Pewaukee, WI, USA
Joined Mar 2002
4,606 Posts
Gary,

I'm really surprised there wasn't more damage. I've had 1s portions that looked like they were squished and from the side they looked like a Z. They still worked and I lightly pounded them back in shape.

I'm going to get a 1mm thick carbin plate to put over the pack, and another to put between the skids and the struts, at $30, the frames are outrageouslt expensive. (I can get both sides for my RappE for $20)

Tony, you could put something over the pinion, but sounds like a lot of messing around when you can just cut some carbon plate quick and shrink it into the pack.. Just my .01..

-P
pwkpete is offline Find More Posts by pwkpete
Reply With Quote
Old Jun 25, 2003, 09:24 PM
Registered User
Joined Apr 2000
2,300 Posts
Gary, You might want to check out my "Snake Oil" thread. I have a Logo10 example and I'd appreciate your comments as to whether it relates to your experience.

Hank
HankF is offline Find More Posts by HankF
Reply With Quote
Old Jun 26, 2003, 02:59 AM
Registered User
GGoodrum's Avatar
South Orange County, CA
Joined Mar 2003
8,094 Posts
Today was a good day...

Well, we finally got some REAL flight data today. My son and I went out to the former Marine air station at El Toro with a friend. He was doing some videotaping, using a gimbaled DV camcorder on a fairly big plane. We used my E-Tech 5s5p and 5s6p packs on the plane, which had a Hacker B50-9XL and a 5.7:1 gear reduction. This worked quite well, which I found interesting due to all the discussion in the eRapp/Hacker thread on gearing, etc.

Anyway, we finally got around to checking out the Logo with the TP 5s4p pack. First we tried a hover, with the canopy off and the wattmeter attached. Power required was about 317W/18.2A/19.8V and after a minute or so I checked the headspeed. It was a solid 1920 (!) rpm. Next we tried a few full-power climbouts and the max reading I saw on the tape later was 549W/30.1A/18.2V. This amased me as the beast had an icredible amount of power! It really shot up like a rocket! After about 4-5 minutes of this I had my son land and I checked the temps. The pack wasn't even warm and the readout showed 94 degrees. The motor was 98 and the ESC showed 104.

At that point, I decided to screw any more testing and we took off the wattmeter and added the canopy. What happened next was pure joy! I had my friend Larry, who's quite the accomplished pilot, put it through a full-on 3-D workout. For the next ten minutes I got to see what this thing is really capable of and it was mind-blowing! I videoed the whole thing and I also recorded the video from the onboard camera. Amazing footage, to say the least. I will edit both into a single video tomorrow and post a streaming link. My son and I watched both about 5 times tonight and it just blows me away! Can't wait until I can fly like that!

My friend Larry said that this was definitely the most powerful electric heli he's ever flown and he's built quite a few. One is a special eRaptor 50 that uses very simple fiberglass frames and a Hacker B50-11XL. It is designed to carry a 3-4 pound camera so it has the absolute lightest of everything on it and is quite a rocket without the camera and mount. He is making a new version with dual -15XLs but until that is flying he said this Logo has more power and that it rivaled his gas Raptor 60/90s in how it handled.

Anyway, I'm a happy camper, to say the least! If nothing else, I think I've proved to myself that LiPos open up the possibility to run higher wind motors at much hgher voltages than is possible with NiCd/NiMH packs. This allows for more power and less current draw. The one "test" I want to do tomorrow is to see if the E-Tech packs will hold up under similar flying loads. We were going to try them today but we used both packs in the plane so it'll have to wait until tomorrow. I also need to do some endurance testing. I don't have an exact timing but from a review of the video there was about 4-5 minutes of hovering and several "rocket launches", followed by about 10 minutes of hard 3-D. We didn't want to push our luck but I think it still had more than a couple minutes left. The chargers (Tritons...) just finished recharging the 2s4p and 3s4p TPs and they took 3600 and 3577 mAH, respectively. Sounds like we still had half-a-tank!

Hank -- I'll check out the thread...

-- Gary
GGoodrum is offline Find More Posts by GGoodrum
Reply With Quote
Old Jun 26, 2003, 09:42 AM
TeamTP,Minicopter,Spartan
misskimo's Avatar
Mississippi 31 years , Now Kotzebue , Alaska 12
Joined Apr 2001
7,454 Posts
cool , I was wondering about the heat at the end of ther flight , sounds like you dont have a heat problem though , no bogging huh? Tony
misskimo is offline Find More Posts by misskimo
Reply With Quote
Old Jun 26, 2003, 10:28 AM
Registered User
GGoodrum's Avatar
South Orange County, CA
Joined Mar 2003
8,094 Posts
No, no bogging at all and the temps were 94, 98 & 104 for for the motor, pack & ESC, respectively.

Now I'm anxious to see how the E-Tech 5s5p and 5s6p packs work in-flight. When I was doing the previous strapdown tests, my sense was that the voltage dropped down quite a bit under extreme loads, causing the current to rise for a given watt reading. With the TPs yesterday, hovering was at 19.8V but full power only dropped it down to 18.2V but this was early into the pack.

-- Gary
GGoodrum is offline Find More Posts by GGoodrum
Reply With Quote
Old Jun 26, 2003, 01:26 PM
17 years on RCG!
United States, NV, Las Vegas
Joined Dec 1996
3,114 Posts
Excellent info Gary!

This just confirms what Ive felt all along. There are 2 ways to power a heli (Well, there are many more, but these would be the 2 ends of the spectrum....):

1) High KV motor, small pinion, low cell count

In general, you can readily achieve the headspeed and power you need by using this approach. BUT, flight times tend to be much shorter. The benefit to this approach is the lighter "disk" (or wing) loading. In my opinion, some helis do in fact benefit from this, such as my RappE conversion.

2) Low KV motor, larger pinioon than the above and a higher cell count

Using this approach does in fact require more cells to achieve the same headspeed. But as youve seen, more voltage under load tends to deliver better and more consistent power. The downside to this approach is the added weight of more cells - but with LiPos, the concerns arent nearly as much.

Lets take the Logo 20 for example. When using motors with KVs of around 800 and 24 cells, the heli was a ballistic missile with very solid power throughout an entire 7 minute flight on 3000s. Now, if you put in a hotter motor with a KV near 1000, it requires less voltage to achieve the same headspeed. While the power to weight ratio (watts per pound) is nearly the same for both models and the higher KV motor did deliver the headspeed we wanted, flight times were shorter...closer to 5.5 minutes using 20 3000s.

The benefit to the latter set up was the decreased disk loading. Manuevers could happen at a slower pace, but you had to be more careful not to "bog" the motor in more agressive styles of flying.

With heavier helis like the RappE conversions, many have chosen the high KV/low cell count approach to save weight. However, just about everyone who flies a Logo 20 chooses to go the opposite way due to its lower weight. Sure, if you used the lower KV motor with more cells in the RappE it would fly very well - but it would also be a bit overweight to fly really well.

The Logo 10 has proven to be much of the same. I first flew mine on an 11L motor and 12 cells. Performance was every bit as good as those flying the 13L on 14 cells...but I used fewer cells to achieve the same results. Problem was, I got 1-1.5 minutes less flight time than everyone else. I just hated the idea of adding 6 more oucnes to my heli with a milder motor to get slightly longer flight times...

But now with LiPos, I sold my 11L motors and have decided on either a C50-13L for the next motor, or quite possibly a motor such as the Aveox. Ive been impressed with the quality of Aveox as I fly some of their newer motors in planks now, and the price is right...as is availability

Im anxious to see your results using the ETecs. In general, what Ive seen is that the ETecs will in fact work well, but wont deliver the same voltage as the TPs. The difference is most evident half way through the flight where the higher voltage of the TPs really shines through in 3D manuevers.

Do let us know what you find out!

Jason
Jason M is offline Find More Posts by Jason M
RCG Plus Member
Reply With Quote
Old Jun 26, 2003, 02:03 PM
Registered User
Joined Apr 2000
2,300 Posts
Great work, Gary.

What you've shown is that we can "have our cake and eat it too" with LiPo technology: power and duration.

Fortunately, our motors don't lose too much efficiency when using higher voltages, only about 10% for a 67% increase in voltage (see my Snake Oil thread). We don't have to worry too much about efficiency with so much duration from the LiPos.

Hank
HankF is offline Find More Posts by HankF
Reply With Quote
Old Jun 26, 2003, 05:49 PM
Registered User
GGoodrum's Avatar
South Orange County, CA
Joined Mar 2003
8,094 Posts
Jason/Hank --

I'm now starting to understand it all. Hank's math has helped fill in some of the blanks and Jason, your real-world experience has been invaluable. Thanks for also hooking me up with Charlie. I had a long chat with him this morning, in fact, and he helped me understand some of the differences between his packs and the E-Techs that you have pointed out before, and that I'm just now seeing, witch is under load, the E-Techs will drop voltage lower than the TPs. Anyway, now that I understand the electrical differences (primarily in cell resistance under load...) I can still document "safe" current margins for using the E-Techs in larger applications.

I'm working on the video as I write this and it really is something! I'm getting giddy all over again!

-- Gary
GGoodrum is offline Find More Posts by GGoodrum
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
WTB Aveox 36/30/2 or hacker C-50 v22chap Aircraft - Fuel - Airplanes (FS/W) 0 Mar 14, 2004 06:10 PM
Aveox 36/30/2 question furyflyer2 Electric Heli Talk 6 Feb 28, 2004 09:38 PM
Aveox 36/30/2 Stearmandriver Electric Heli Talk 43 Feb 26, 2004 06:54 PM
Question Logo 10 - Mega 22/30/2? gregw Electric Heli Talk 4 Oct 07, 2003 02:32 AM
Phoenix 60 governor mode with an Aveox 36/30/2? GGoodrum Castle Creations 10 Jul 30, 2003 06:21 PM