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Old Jun 07, 2010, 11:23 AM
HAL... Open the damn doors!
jfetter's Avatar
Miramar, Florida
Joined Jul 2007
8,329 Posts
Quote:
Originally Posted by dag214 View Post
Sorry Jack you are 100% wrong buddy.

If you will look back at my testing last fall (in my post) I was pulling over 64 amps, and the ESC went into over heat. This was in testing the 20-14 at 4400 RPM. Because of the lack of hi-flow air moving over the ESC with it located in the back of the nacelle after 90 seconds at 85% power it shut down. Now at 60% which I think will be cruise power they over temped at 6 minutes. The nacelles do not have a ton of air getting to the back of them with a clear hi-flow movement. Hacker gave my the link to the fans as guys that hide their ESC in scale warbirds may chose to use them instead of cutting holes in their cowlings. My ESC got to something like 145 degrees, I may be wrong, might have been hotter.

Rock On Buddy!
Dag
Not to argue but running electrics up static doesn't offer a real-world picture of airflow when in the air, there is always way more airflow than predicted. I am not faulting you my friend, I know you want to mimick conditions on the ground but in this case I just don't see anything hotter than 115 - 120F during normal flight. Now this includes you running the cooling tube that you have in your plans, I'm not saying you need no cooling, just no fan.

Now I would never tell you what to do, you know what you're doing and you're footing the bill but one day when you have time, long after the maiden and other fine tuning, pull the fan off and see for yourself. I didn't believe it either when I started out but unless you have NO airflow, the ESC really isn't an issue, in fact I have a few 12S setups where the ESC doesn't even get warm enough to tell they've been flying...

Jack
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Old Jun 07, 2010, 11:30 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,899 Posts
Quote:
Originally Posted by dag214 View Post
Well my motor system testing last night did not go well. With a fan blowing on the ESC I still had a over heat shut down at 100 C. When I look at the ESC controller box, it is set to shut down at 100 C. With the 65" leads it is just pulling to much load on the ESC. The motor is cool, but the first 10" of the 10 gauge wire coming from the ESC is very hot. I am going to re-do the test tonight at 48". My most favorable location for the C/G to be where I need it with out adding ballast would make me need at least 48" leads. I can still go down to 30", but puts the batteries in a location that will force me to add weight, something I do not want. But I have save about 4 pounds in my new wing design, that I might just have to trade here.

I have a ton of data, and don't have time to post all now, but here is some of it (I also did this test at a simulated flight power condition).

Thanks, DAG

Max RPM 4110-00:55 minutes (take off) (99 per pound).
Cruise power RPM 3200-05:31 minutes (58 watts per pounds).
watts per pound.
Motor run time-6:59 minutes
Max Voltage-33.64V
Min Voltage- 27.55v
Min Temp-20C (00:50 minutes)
Max Temp-100C (2:36 minutes)
Battery used 2850 ma out of 3900 pack.

ESC settings:
Temp Protection-100C
Brake-off
Operation Mode-Aircraft
Timing 24 degrees
Freq-8khz
Accel-0-100 1,0S
Accumulator type-LI-Io/Pol/FE
Number of Cells-8
LI-XX Cutoff Volt Per cell 3.2
Off Voltage set-25.54V
Cut off-slow down
Initial Point-Auto
End Point-1.80ms
Auto Inc. End Point
On From-1.80ms
Throttle curve-linear
Rotation-left
Timing monitor-off
Setting-r/c-on
Quote:
Originally Posted by dag214 View Post
Something really interesting.
I am now starting to log most the data I am getting off my motor test. Not sure what this means, but my batteries really do seem to be different. I am not going to mention names except for the good ones (and I know some of you will say, hey tell us) but I don't want to sound like a kiss a _ _. But When I take my ThunderPower and 2 other batteries I got, I find some numbers that don't make sense. I will post more of the raw numbers later, but my TP pack at the same load, and same time ran uses less battery. I have only tested this on my 5000mHa set up. But the difference is as much as 15%-18%.

I am not a expert at these electric set-ups. But 15% is a bunch. I will be honest I had 1 battery manufactures (their rep) want to give me batteries, and 2 other sell at a discount for my plane, I said no to giving me any, but would buy a few to testing. They stated that if it was just for testing then they would loan them to me. Loan me a few before I decide on buying 2 sets of 6 packs of 8C. Well the difference between 2 of them was not a lot, about 5%, but some. The weight of the TP would decide that contest, but the 3rd battery (imported) at best is still less than 15% of what the TP will do in capacity. And the import seems to always take different charge times for the same times ran.

Ok, Ok, enough of trying to talk electrics. I have seen a bunch of threads state how expensive TP is, but they are so constant, that with 6 motors it is a no-brainier. I also have 3 packs of TP for my F4U Parkzone, and they are so constant.

One last cool thing, I think my Master Spin 77 has a over heat protection circuit. Last night while hammering the throttle at the top 25% power range the motor went to (I am guessing) 25%. I thought "crap!" what did I burn up? So I put my hand on the ESC and MAN was it hot, then about 30 seconds later I had my full power back. So air over the ESC is a good thing.

I will start posting more info by Sunday after I run more tests.

Cheers, DAG
Quote:
Originally Posted by dag214 View Post
Here is what I got done last night.

2 more coats of paint in my gear door plug.
Started laying out my test mock-up of my longest power run for my #1 and #6 motors. I only need 55"-58" from motor to ESC, but I am testing at 65" to give me a bit of head room. All the other motor to ESC runs will be less than 36"

And after looking at what I actually have to do I think I will have the B-36D 100% done in February 2010. That is adding an extra month to what I think it will really take. One thing that will slow me down a little is all my nacelles will now be FG and making the molds will take me about 3 weeks.

DAG
Quote:
Originally Posted by dag214 View Post
Here is my motor test. I think I have a winner!
I still think I will never use more than 65% power.
At 1950 watts I should have 110 watts per pounds at 100 pounds. I still think she will fly fine at 70 watts per pounds with 6 motors.

DAG

http://www.youtube.com/watch?v=prFTjc5-GR4
Quote:
Originally Posted by jfetter View Post
Two observations Dag, first I don't think heat will be an issue, I'm running 75 Amps plus on my smaller 6S setups that are almost identical to yours and they seldom reach higher than 45C, and that's in South Florida. The difference is air flow, even slight air flow will keep them cool and I've seen your design, it should prove more than adequate. Second, if you do opt for fans please do not run them from the RX. The ESC you have is made from the best components available and even that is optically isolated from the RX to prevent the introduction of any noise from the ESC. These fans you have should have a seperate 2S Lipo running through a 5.1V regulator for power, not powered from the RX bus. I know you have redundancy, it's not that, it's the RF you are introducing to a system that otherwise has been designed to be isolated...

Jack
It all start at posy 3944.

Look at these:

Dag
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Old Jun 07, 2010, 11:36 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,899 Posts
Quote:
Originally Posted by jfetter View Post
Not to argue but running electrics up static doesn't offer a real-world picture of airflow when in the air, there is always way more airflow than predicted. I am not faulting you my friend, I know you want to mimick conditions on the ground but in this case I just don't see anything hotter than 115 - 120F during normal flight. Now this includes you running the cooling tube that you have in your plans, I'm not saying you need no cooling, just no fan.

Now I would never tell you what to do, you know what you're doing and you're footing the bill but one day when you have time, long after the maiden and other fine tuning, pull the fan off and see for yourself. I didn't believe it either when I started out but unless you have NO airflow, the ESC really isn't an issue, in fact I have a few 12S setups where the ESC doesn't even get warm enough to tell they've been flying...

Jack
In testing I had a 15mph wind over the ESC, and 10MPH to un-stall the motor and prop to create a full load. I got all my data for this test rig form a guy at Lockheed Martin.

Even Hacker suggested I use the fans since I can't be 110% sure of what my airflow will be on a ESC with a motor that is fully loaded.

Now I think your right that this will be a hugely over powered aircraft, and I bet once I get her all trimmed out that I will be in the 30-45 amp range, but I just have to be 110% sure that my maiden will not see any type of power plant failure.


Rock on buddy.

Dag
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Old Jun 07, 2010, 11:48 AM
HAL... Open the damn doors!
jfetter's Avatar
Miramar, Florida
Joined Jul 2007
8,329 Posts
Quote:
Originally Posted by dag214 View Post
In testing I had a 15mph wind over the ESC, and 10MPH to un-stall the motor and prop to create a full load. I got all my data for this test rig form a guy at Lockheed Martin.

Even Hacker suggested I use the fans since I can't be 110% sure of what my airflow will be on a ESC with a motor that is fully loaded.

Now I think your right that this will be a hugely over powered aircraft, and I bet once I get her all trimmed out that I will be in the 30-45 amp range, but I just have to be 110% sure that my maiden will not see any type of power plant failure.


Rock on buddy.

Dag
Wait, you're not using any of the original extended leads though, right? I thought you were back to standard leads from the ESC to the motor and only extending the Battery-to-ESC leads by maybe 20"?

Jack
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Old Jun 07, 2010, 12:05 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,899 Posts
Quote:
Originally Posted by jfetter View Post
Wait, you're not using any of the original extended leads though, right? I thought you were back to standard leads from the ESC to the motor and only extending the Battery-to-ESC leads by maybe 20"?

Jack
Your right buddy. In my next testing I may not even have a temp problem, but I am designing for it now just in case.

We shall see soon as i want to test a full power run up in a completed nacelle by July.

Thanks, Dag
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Old Jun 07, 2010, 12:25 PM
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ErcoupeEd's Avatar
Joined May 2004
1,487 Posts
You're better off to go to overkill and 110% for now.
You can always backoff on the airflow, and flight testing will
tell the tale, checking temps after each flight.

With all the time and everything you have you have in this airplane, I'd go 110 % myself.
Because no one wants to think, If I'd only used overkill, at least this first time, as you stand looking at pile of lumber laying on the ground.
It will take a few flights to find the "envelope" it flies best in.

Ed
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Old Jun 07, 2010, 03:11 PM
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USA, CA, San Bernardino
Joined Oct 2009
100 Posts
B-36 Electrical System

Quote:
Originally Posted by ErcoupeEd View Post
You're better off to go to overkill and 110% for now.
You can always backoff on the airflow, and flight testing will
tell the tale, checking temps after each flight.

With all the time and everything you have you have in this airplane, I'd go 110 % myself.
Because no one wants to think, If I'd only used overkill, at least this first time, as you stand looking at pile of lumber laying on the ground.
It will take a few flights to find the "envelope" it flies best in.

Ed
Hi Damon,

I got a kick out of watching your daughter stand behind the prop during the test. She was very excited and I think that is great that your kids can share this with you.

I have to agree 100% with what Ed said above. You have a lot invested in the project to take chances. Go with what feels best to you!

Rock On Buddy!

Gary
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Old Jun 07, 2010, 04:22 PM
War Eagle!
sneasle's Avatar
United States, AL, Huntsville
Joined Sep 2006
2,843 Posts
Spinner back prototype #4 is on the lathe being cut, 2 and 3 were.. interesting.. attempts...

2nd one just didn't come out right, the 3rd one got yanked out of the chuck by the boring bar, not sure how that happened as I wasn't there.

#4 is on the lathe and was cutting the finishing pass on the exterior at 4pm, interior should be bored out as of tmrw, I'll go back and check and measure on Weds and if it looks good they will cut the other 5.

Pics and video to follow.
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Old Jun 07, 2010, 08:17 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,899 Posts
I think you will see why I feel I may need a fan on the ESC, having the ESC on the firewall with out any direct air makes me nervous. This is what I got done yesterday morning, and about an hour tonight.

Thanks, Dag
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Old Jun 07, 2010, 08:27 PM
War Eagle!
sneasle's Avatar
United States, AL, Huntsville
Joined Sep 2006
2,843 Posts
Cap plate looks good. If you wouldn't mind, before you install them for the last time, run a bead of silicon around the base of the capacitors.
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Old Jun 07, 2010, 08:31 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,899 Posts
Quote:
Originally Posted by sneasle View Post
Cap plate looks good. If you wouldn't mind, before you install them for the last time, run a bead of silicon around the base of the capacitors.
LOL, guess I should have added more, when I said insulate that is what I meant. I plan on adding silicon, and hot-glue rubber to insulate and secure the caps.

Thanks!

Rock On!
Dag
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Old Jun 07, 2010, 08:32 PM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
5,899 Posts
Quote:
Originally Posted by sneasle View Post
Spinner back prototype #4 is on the lathe being cut, 2 and 3 were.. interesting.. attempts...

2nd one just didn't come out right, the 3rd one got yanked out of the chuck by the boring bar, not sure how that happened as I wasn't there.

#4 is on the lathe and was cutting the finishing pass on the exterior at 4pm, interior should be bored out as of tmrw, I'll go back and check and measure on Weds and if it looks good they will cut the other 5.

Pics and video to follow.
Very cool!
Can't wait to fit it all up, and then test.

You are one hell of a guy!

Dag
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Old Jun 07, 2010, 08:37 PM
War Eagle!
sneasle's Avatar
United States, AL, Huntsville
Joined Sep 2006
2,843 Posts
Here is the video, pics attached below.

Video shows a single pass, not sure what it's set to, but it's cutting very slowly.

CAM of B-36 spinner back (1 min 4 sec)
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Old Jun 07, 2010, 08:45 PM
Use the 4S Luke
feathermerchant's Avatar
USA, TX, Euless
Joined Aug 2003
9,341 Posts
Hey Dag you can use something like a Castle BEC at each motor and run your fans from the motor batteries. That should save wiring and you'll have the ultimate in redundancy.
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Old Jun 08, 2010, 02:51 AM
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United States, ID, Rexburg
Joined Sep 2008
6,441 Posts
I forget when you say things like I am going to put electronics in the nacelles just how big your aircraft is, then you see the pics and it makes perfect sense to put them there. I do know that the 36's were never particularly great for engine cooling, and scale being as full scale you might want to make sure of your air flow through the nacelles first....
Foo
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