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Old Jan 27, 2010, 02:07 PM
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Richard Evans's Avatar
USA, TX, Canyon Lake
Joined Jul 2006
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Jim, these packs in the picture are not the 4000 MAH packs, 4000 MAH packs are 6.3 inches long, the 5000s are only 5.25 (much easier to fit!)
the problem I was referring to are with packs that are 6.3 inches long

Take your ruler with you and measure those platinum packs and you will see that you can't be fitting the 5000's and saying that the 4000's are virtually the same.

Don't get me wrong. I like the EPS 45c packs, they are a great price and will work well for me, I am only being persistent for the sake of accuracy and to help others on the thread understand how these will work in the Spark if they want to use some.

RE

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Originally Posted by JimDrew View Post
I just checked our 5S 5000mAh packs iin my Spark.

There is more than enough room to have them over/under each other. In fact, 6S5000mAh packs fit (but my cockpit kit would have to be removed or modified).
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Old Jan 27, 2010, 03:06 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,679 Posts
Huh? Tam uses our 4000mAh packs all of the time in the stock mounting location. I believe the 4000mAh are shorter than the 5000mAh packs. I will go grab a set from inventory and check them.

Again, our Platinum packs are 100% indentical in size to our Pro (black) packs.
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Old Jan 27, 2010, 03:16 PM
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kevin's Avatar
ohio
Joined Aug 1999
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i use the 4000 packs in the stock location. 6s on bottom of the tray and 5s on top. fits fine even with cockpit kit.
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Old Jan 27, 2010, 03:26 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,679 Posts
Fit even better!

The 4000mAh packs are just a little shorter than the 5000mAh packs.

There is no need to put them in the plane the way you have done.
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Old Jan 27, 2010, 03:41 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,679 Posts
Another pic with a ruler

Here is a picture of the 5S 4000mAh packs with a ruler.
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Old Jan 27, 2010, 03:57 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,679 Posts
We see the problem! Either there are two versions of the Spark, or you put the bulkhead too far back into the fuse. Look at my pictures. See the white knob that holds the tray in place? Now look at that versus the curvature of the inlet ducting. Now, look at yours. You will see that your knob is actually into the curved area, where the normal stock location is quite aways (maybe 1") more towards the nose of the plane.
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Old Jan 27, 2010, 04:08 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,679 Posts
Can you take a picture of the inside of the fuse with the batteries removed?
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Old Jan 27, 2010, 05:16 PM
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Richard Evans's Avatar
USA, TX, Canyon Lake
Joined Jul 2006
342 Posts
I see, I think you may be on to something. I bought this plane from John already built so I assumed it is just like everybody else's When I get home in a couple of hours, I will investigate and post a picture. If the forward bulkhead is in the wrong place, maybe I can relocate it to the correct location, I would rather have the weight distributed more central to the horizontal centerline of the fuselage. I do know that the measurement from the rear bulkhead to the knurled knob is the same as the battery length; 162mm. On your spark it is not I'm sure. Anyway, I will find out in a few hours.

Thanks for listening to me.

RE
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Old Jan 27, 2010, 07:40 PM
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Richard Evans's Avatar
USA, TX, Canyon Lake
Joined Jul 2006
342 Posts
It looks like there was a mod done on mine probably to accommodate a longer nose wheel strut I think the forward bulkhead was moved back and the tongue cut off on the horizontal battery holder thingie.
I will post pictures.
The bad news is that It looks like it would be difficult to change it back to factory, because there are very well done epoxie fillets and I would have to redo the nosewheel steering servo mount, and then there would be the problem of the nosewheel hitting the former when the gear retract.

The good news is that no one else will have any problem fitting the batteries and I have found a decent solution anyway. I do really like the landing gear that the slightly nose high attitude looks just right for grass field takeoffs.

This is a good mod to solve the problem of nosewheel interference and If John (techspy) hadn't done it, I might have done the same thing. I think these landing gear are great (Jet1a mains and Springair nose retract with the TAM strut) and He set it up for maximum ground clearance which is good for what I want (grass field operation). John, if you are reading this thread, thanks and you might want to check in and validate what I am presuming.
Pictures below.
RE


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Originally Posted by Richard Evans View Post
I see, I think you may be on to something. I bought this plane from John already built so I assumed it is just like everybody else's When I get home in a couple of hours, I will investigate and post a picture. If the forward bulkhead is in the wrong place, maybe I can relocate it to the correct location, I would rather have the weight distributed more central to the horizontal centerline of the fuselage. I do know that the measurement from the rear bulkhead to the knurled knob is the same as the battery length; 162mm. On your spark it is not I'm sure. Anyway, I will find out in a few hours.

Thanks for listening to me.

RE
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Last edited by Richard Evans; Jan 27, 2010 at 07:46 PM.
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Old Jan 27, 2010, 07:41 PM
Los Gatos Airport
California
Joined Aug 2008
115 Posts
The forward bulkhead is to be insalled by the user when he decides which batts to use.
I know I had to install it myself after confirming I could get the 5S 5000s in.
You need room to move them forward enough to get the rear tab in place.
I don't think that Tam is using the batt tray supplied with the Spark
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Old Jan 27, 2010, 07:47 PM
Los Gatos Airport
California
Joined Aug 2008
115 Posts
Yes, it looks like your batt tray has been shortened abt 3/4 inch. With the stock length, the nose wheel is a tight fit, coming right up to the bulkhead. I even thought about cutting a bit of a notch in it but close was good enough.

Jim
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Old Jan 27, 2010, 11:44 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
15,679 Posts
The main gear almost touch together, and there is no need to mod the nose gear - can't get any longer. This is an odd issue for sure.
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Old Jan 28, 2010, 02:19 PM
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Herb's Avatar
Irvine, Calif USA
Joined Feb 1999
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Quote:
Originally Posted by Richard Evans View Post
Let me check to see if I understand before drilling some holes. I plan to put the controller in the opening at the rear of the cockpit above the duct.
then I can drill two small openings in the duct to the rear of where the heat sink ends ...
Make sure you have some significant cooling around that esc.

The Jazz/Jive run a lot cooler than other ESC's due to perhaps better design/mosfets but most likely due to better algorithm & waveform at reduced throttle. As always, you get what you pay for.

You have the ESC in the right place, where it can be taken out/replaced without ripping out fan & ducting

In my Rafale I have both Jazz's up front in the cockpit with no cooling and they get barely warm.

But ...

some things get lost in translation , when Kontronic says the Jive/Jazz needs no airflow at reduced throttle my guess is that they actually mean : no forced airflow, i.e. in the form of a fan as in the PowerJazz .

So the moral of the story is: as always test your setup by doing a dry run at home and check temps to see if YOUR esc with YOUR installation and YOUR flying style will heat up or not.

In case, just add a small $2 graphics card fan, http://www.rcgroups.com/forums/showp...8&postcount=97 that will kepp your esc nice and cool.

Btw, of the 10% of all EDFs that ever make it to the maiden (as opposed to hanging unfinished on the wall), around 50% are lost on the maiden eg during the last upwind turn for a landing, due to incorrectly dimensioned components

.
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Last edited by Herb; Jan 29, 2010 at 11:21 AM.
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Old Jan 28, 2010, 02:34 PM
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techspy's Avatar
USA, NC, Matthews
Joined Aug 2008
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Yeah when I got my first Spark the bulkhead was already in place. After my many problems with the wire struts and grass runway use, I found the Jet1a's and they worked great except that they were longer and that caused the issue with the nose up. So, when I built this one the bulkhead was not installed and the mains cutouts were not done either. I then was able to set it up where everything fit perfectly, including the lipos and the CG was spot on. I never worried about other lipo's being enough of a size difference to cause a problem. After seeing some Sparks have issues getting to speed quickly enough on grass, I wanted to do all I could to avoid that being that all I had access to was a poorly laid out grass field. In hindsight, pushing over 5k watts probably would have overcome any lack of nose-up issues. It may appear different to more experienced "Sparkers" but when I look at how quick my first build got airborne on our grass field, it sure seems like the setup was spot on for grass.

Anyway, glad you got it worked out Richard. Good luck on the maiden!
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Old Jan 29, 2010, 03:21 AM
The blade numbers go up to 11
stumax's Avatar
Sydney, Australia
Joined Aug 2002
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Quote:
Originally Posted by STEVEAIR2 View Post
Hi Stu
could you show a line diagram of what you mean regarding the cooling?
Cheers
Steve
Sorry, Steve, I've been trying to get around to making a 3D model for you to show it but I just can't get enough quiet time at the computer at present. I don't this this method is really suitable for the Spark, though. I think Ron's method of adding a small CPU type fan is the way to go, and make sure there is somewhere for air to enter end exit the fuselage.

Stu.
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