Receiver/bettery/ESC packing question - Indian V glider

[ahdofu]

There isn't much room inside the fuselage of this glider. I am finding it necessary to have both the RX and the ESC (Dualsky XC40A) mounted adjacent to one another and tucked close to the servo tray. This provides enough room for the battery to be mounted on its narrower side inside the fuselage. From a heat and interference standpoint is this a no-no?

 

[Konrad]

A photo would help. Yes, to the RF concerns. And more likely no for the thermal concerns, assuming there is air flow. I would think you could but the RX way in the back up against the bottom of the wing. Again a photo would help.

 

[Konrad]

Wait, you have the ESC and RX in the back? What are you using for a battery? Sounds like a lot of wires running around inside the fuselage. Most of us have very short motor the ESC wires and just long enough ESC to battery wire to allow for easy manipulation and shifting to find the proper CG.

 

[ahdofu]

The sketch shows what the manual is suggesting for the installation. I don't have enough room so I'll have to place both the RX and ESC where I've circled.

The attached photo shows how I was thinking to position RX & ESC. Once all the leads are connected, the whole thing will go inside and will be adjacent to the servo tray. In the photo servo tray ends where the wing hold down screw holes are. The picture also shows the battery. With the RX & ESC tucked inside, I'll have enough room for the battery except that it will need to be installed on its side.

 

[ahdofu]

Perhaps the battery is too long/wide for this installation. It is a 3S, 1300mah battery. I picked the motor/ECS/battery based on what had been recommended earlier.

 

[Konrad]

Wow that esc and Rx look huge. 1300 sounds like an appropriate size. Yes, you could go down to 850mAh cells But first let's find out where the CG is. Stuff the items just to see where's the mass. If need be you can tape the components to the fuselage to move things around. If you are nose heavy going down in battery size would help. 40 amps seems a bit much. I think going down to 25 amps would work. I like to size my power for a glider like this at 70 to 100 watts per pound. To be honest I would go with 150 watts per pound as you have a "D" tube wing

 

[gp49]

Second on the receiver and esc physical size being super large. Especially the receiver. Can you get a smaller one?

 

[Konrad]

Here is an idea of what normal sized components look like today.

P.S.
Top models always seems to recommend a very nose heavy GC. So see what you can do to get the equipment in there but with the CG aft by about 5mm to 8mm. Add lead for the maiden and then thank yourself for your forward planing as you remove the lead to get the model in proper trim.

 

[ahdofu]

I know you diehard glider folks will cringe when you read this so apologies beforehand. The way I have it configured, the model will balance by adding 0.25 OZ weight to the tail. I can reduce the tail weight or perhaps do away with it completely if I were to reverse the position of the battery and the ESC/RX. However this way, swapping batteries will become quite challenging.

If I knew what I know now, I would have opted for a narrower battery pack. My current pack is 34 mm wide. A 25mm wide pack would lay down on its wide side with ESC underneath it.

My RX is a Corona 8-channel. It measures (mm) 56x27x13. The one in the above photo is around 30 mm long which is considerably shorter than my RX. The next step down for me would be a Corona 6 RX which looks similar to the one in the picture but I don't know its dimensions.

Looking at the nylon enclosure of the ESC in the picture, It seems to be around 40x20. My ESC measures 58x27x15.

 

[Konrad]

I fear I may have been the one giving you recommendations. This is a problem with internet shopping, one can't test fit components in the store. I think my recommendation were focused on the BEC on board the ESC. The smallest one Aloft carried at the time that had a switching BEC (this is very important) was the one you have.

I use Castle Creation ESC for most of my high value models. They are very well made and designed. And to that point if they make a mistake that recall the product. Well worth the price. The Talon is a great entry level ESC with fantastic performance. But because of its size 19mm x 40mm x 9mm (at the cap) it will need airflow. As this is looking like a 1.5lb model you won't be needing more than 200 watts. So that Talon 25 would be perfect.

In the old days I often removed the RX's hard plastic case and used heat shrink to protect against shorts.

I select my batteries by size and weight needed to obtain the desired balance. I then look a capacity and impedance to find the power set up I want.

 

[ahdofu]

There is finally a third way to position things (see pic). Here RX lays flat on its back per manual. (RX antenna will be re-positioned of course.) ESC and battery are now closely coupled. Again I don't know whether this poses a thermal issue or not. I will have to shorten the ESC and battery leads but this is not a big deal.

Regarding the forum recommendations - it is always hard to know whether something will fit or not especially when all one has are pics. That is water under the bridge. I like to use what I have if I can make it work. Later on I can always swap and customize components.

 

[Konrad]

Not a thermal concern as long as there is some air flow. Are there any air inlet holes and exit holes (the tail boom may be enough)? The plans show the use of a Turbo spinner. Can we see the spinner and firewall to ascertain the air inlet flow. If keeping to 200 watts or so the ESC won't get hot. Have you test run the power system?

 

[ahdofu]

There is the tail boom of course except that there would be some flow resistance (wall friction, v-tail pushrod wires & servo tray in front). Other than holes on the motor mount, there are no other air intakes.

 

[Konrad]

Most would be surprised at how little airflow is needed to drop the tempratures. If not using a "Turbo" spinner you will have to add an inlet hole.

 

[ahdofu]

Geez ... I totally missed that. It has a turbo spinner so there is an intake

 

[Konrad]

From a flow perspective a hole on the bottom is better. But from a practical view the top hole keeps the dirt out and as most of the cooling will be done during the glide portion of the flight this is actually preferred. (Note this is not a NACA scoop, it just looks like one).

 

[Konrad]

Geez ... I totally missed that. It has a turbo spinner so there is an intake

Bad luck that the battery lead blocked that view.
Can we see that the motor doesn't block the flow from the firewall?

 

[ahdofu]

Well in a way it does
P.S one of motor mount screws is inside the motor cavity. I am yet to fish it out with tweezers.

 

[Konrad]

OK, there is a myth that cooling air will flow down the windings. In the old days of the Mabuchi canned motor the copper fill was so poor that there may have been some truth to that. But with the much higher efficiency motor of today, not so much (not at all).

Please open up the holes as indicated this will allow the air to flow around the motor and down the fuselage carrying away the heat.

 

[ahdofu]

Will do. Do I still need to adopt your NACA inspired intake as well?