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Hi, Anybody started building Tonys recent free plan the A10, I have started cutting the parts but it is rather intricate and time consuming

but its keeping me occupied now the winter draws ever closer. There is usually a video on Tonys website but not seen one regarding the A10.

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  • 2 weeks later...

Hi, Just started cutting the wing 

 ribs but find it impossible to cut the ribs with the tab intact so i will have pack the trailing edge up when assembling the wing. The build is coming along fine and also started assembling the Nacelles.

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  • 2 weeks later...

Has anyone figured out an elegant way of running the wires from the engine pods to the fuselage? It’s not clear from the plan or photos, looks like just pass them below the support and cover over.

 

Is there a best way to connect the battery to two ESCs? A short single length and split to two longer lengths to reduce the length carrying the high current?

 

I’ve no idea if this post will make it as I’ve had terrible problems logging in for weeks, still not working.

 

thanks all

 

J

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Your post did make it!

 

I haven't seen the plans, but looking at Tony's build photos I think I would be tempted to install the fans at the front of the nacelles, then drill three holes through the solid balsa pylons that the motors attach to, one for each motor wire, then put the ESCs inside the fuselage.  That's the way it is with my twin EDF Learjet.  Most EDFs work best if they have a tapered efflux tube -- IIRC Wemotec recommend a taper to 80% of the fan diameter.

 

As a general rule the ESCs should be as close to the battery as possible, with the motor leads then being as long as required.  For battery connection I would do as you suggest, splice the two ESC battery connection leads together and join them to a short single length of suitable gauge before attaching the plug.  In the case of my Learjet I use two batteries in parallel, so I join the ESC leads together and then split them again for the battery connectors.  I could in theory have connected each battery and ESC direct to its own motor, but by splicing them together you ensure that both motors get exactly the same voltage as each other throughout the flight.

Edited by Allan Bennett
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Jason,

I ran the motor leads out of the  motor pod underneath the pod 'supports' at the back.

You don't really notice them. You can just about see then in Tony's build photos.

 

Allan,

George at 4-Max recommended extending the battery leads as modern ESC can now cope with this. The battery leads where then joined together to make a sort of 'Y' lead. I also shortened the Motor leads to be able to fit the wiring and ESC within the Pod.

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12 hours ago, Colin Low 2 said:

Allan,

George at 4-Max recommended extending the battery leads as modern ESC can now cope with this. The battery leads where then joined together to make a sort of 'Y' lead. I also shortened the Motor leads to be able to fit the wiring and ESC within the Pod.

 

That's interesting.  I know that many modern ESCs have more capacitors on their battery leads to cope with the effects of long wires but, even then, it must be good practice to reduce the strain on them by keeping the battery leads as short as possible.

 

What about the position of the fan in the nacelle?  My recent experiences with ducted fans are that it's the intake configuration that has the greatest effect on thrust, and the most efficient seems to be when there's no intake duct at all, just a nice rounded lip at the front of the impellor.

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23 hours ago, Colin Low 2 said:

I ran the motor leads out of the  motor pod underneath the pod 'supports' at the back.

Jason, that should have said 'front'. See picture

 

Allen,

Possibly not the best position, but it works. It also allows enough room to squeeze the ESC in, if the fan was at the front it starts to get complicated

IMG_20211109_201627_resized_20211109_101259392.jpg

IMG_20211109_202013_resized_20211109_101300348.jpg

IMG_20211109_201636_resized_20211109_101258871.jpg

IMG_20211109_201333_resized_20211109_101259805.jpg

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Thanks for the information, the photos are a big help too.

I’m going to mount the escs in the pods so they get some cooling air over them. 

On the intake geometry, I’m going to look at printing a duct shape with a cutout to clear the esc. If I ever get started, I’ll post some pics.

 

thanks

 

J

 

Big thanks to Jon Iverson for helping me access the forum again!

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On 09/11/2021 at 20:20, Allan Bennett said:

 

That's interesting.  I know that many modern ESCs have more capacitors on their battery leads to cope with the effects of long wires but, even then, it must be good practice to reduce the strain on them by keeping the battery leads as short as possible.

 

What about the position of the fan in the nacelle?  My recent experiences with ducted fans are that it's the intake configuration that has the greatest effect on thrust, and the most efficient seems to be when there's no intake duct at all, just a nice rounded lip at the front of the impellor.

 

Allan, Some manufacturers still quote that battery to ESC leads should be kept short or that capacitors should be fitted, however that is not the case with 4-Max (just ask George).

My DC3 and Grumpy Tigercub, Focke Stick, WooHoo, BH Mosquito all have central battery/batteries and nacelle mounted ESC's

 

There is a distinct advantage of having ESC's in nacelles/near the motor and that is cooling is available. Fuselage ESC cooling might work if you are batting about, but slow the air speed right down and the ESC's will be generating a lot of head and cooling could be marginal compared with airflow off the prop/fan.

 

 

PS if cheap ESC's are purchased then the capacitor specification may be lower and thus with extended battery/ESC leads result in failure. The only twin ESC issue was a very poorly soldered motor bullet (OEM) that failed under WOT (not a 4-Max product) resulting in a bicycle clip moment. 

 

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It's not manufacturers I've heard quoting short battery leads, but people with more knowledge (and test equipment!) of electronics than I have, in another forum.  They make the point that long battery leads won't destroy your ESC immediately, but will degrade its capacitors over time, resulting in eventual failure.  So models that are only flown once in a while, no matter how old they are, may never reach the point of ESC failure.  But I also accept that modern ESCs often have more capacitors than older ones (you can add capacitors anyway, if you want), so will be more tolerant of long battery leads.

 

Most single-engine electric planes have the ESC in the fuselage, so I don't think that it being a twin makes that much difference when it comes to ESC temperature.  It's the fact that my Learjet, with similar power plant configuration to the A10, has its ESCs in the fuselage that made me suggest it for the A10, rather than trying to cram them in the nacelles.  But, whatever works . . . . . 

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  • 3 months later...

I've been away for a while, but last week I ordered and received my A10 full kit, and the fuselage is well on its way to being structurally complete, with nacelle framing added today.  Motors and ESCs arrived from 4-Max today too.  

 

Having got this far I can see that my earlier suggestion of putting the fans at the front of the nacelles for better efficiency is impractical.  But the 50A ESCs supplied by 4-Max seem, in my view, too large to fit comfortably inside the nacelles.  I can see in his photos how Colin Low 2 has got them in, but nevertheless I'm going to extend the motor wires and install the ESCs somewhere inside the fuselage instead.  This will make them more accessible for my arthritic thumbs, and will also allow me to run the motor wires into the fuselage near the rear of the pylon, where they'll be even less visible.  

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20220303_152558.thumb.jpg.e5f86a92bdecce9a24e2b55322566ba7.jpg20220303_152705.thumb.jpg.4f14406c3692201a6859c04fc10a8044.jpg

 

Here's my wiring layout.  I was initially tempted to drill another hole through the former, below the nacelle mounting plate, to bring the wires directly to the hole in the fuselage side, but that looked like it might weaken the former too much, so I used the stock holes to pass the wires through.  Obviously there'll be a cutout in the nacelle sheeting to accomodate the wires.  I've extended the motor wires anough that the ESCs can sit in the fuselage somewhere around the wing trailing edge.

Edited by Allan Bennett
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The reason I've now discounted mounting the fan at the front is that it's angled compared to the alignment of the nacelle.  If it were mounted at the front it would need an angled/curved thrust tube to get the thrust direction right.  That's possible, of course, but it would probably add weight compared with TN's simple short straight tube made out of laminate.

 

For me the ESC location is simply a case of ease of access.  My digits don't cope well with fiddly things in confined areas!

 

The fan's small diameter compared with the diameter of the nacelle means that the flow of intake air will be adequate despite the length of the intake duct.  I haven't seen any flight reports other than TN's in his build notes (are there any other reports?), but presumably the system works well.  One thing that has crossed my mind is that, if thrust seems to be marginal, fan efficiency might be improved by having a smooth intake duct, to eliminate the turbulence that must be caused by the exposed nacelle structure -- especially the front former N1.  But that's more weight.

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On 09/11/2021 at 07:25, Colin Low 2 said:

Allan,

George at 4-Max recommended extending the battery leads as modern ESC can now cope with this. The battery leads where then joined together to make a sort of 'Y' lead. I also shortened the Motor leads to be able to fit the wiring and ESC within the Pod.

 

On 09/11/2021 at 20:20, Allan Bennett said:

That's interesting.  I know that many modern ESCs have more capacitors on their battery leads to cope with the effects of long wires but, even then, it must be good practice to reduce the strain on them by keeping the battery leads as short as possible.

 

On 14/11/2021 at 20:18, Chris Walby said:

Allan, Some manufacturers still quote that battery to ESC leads should be kept short or that capacitors should be fitted, however that is not the case with 4-Max (just ask George).

 

...PS if cheap ESC's are purchased then the capacitor specification may be lower and thus with extended battery/ESC leads result in failure. The only twin ESC issue was a very poorly soldered motor bullet (OEM) that failed under WOT (not a 4-Max product) resulting in a bicycle clip moment. 

 

 

I'm sorry, I know many here are big advocates of 4-Max on this forum but I am with Allan on this one. The physics has not changed overnight, and the two failure modes for ESCs caused by long battery wires are well understood (taken from this RCGroups thread on the topic)...

  • Voltage spikes higher than battery voltage. The spikes can destroy discrete transistors and integrated circuits through breakdown. A good analogy for this is water hammer within a pipe when you turn off the tap quickly.
  • Higher current flowing through the standard input capacitors already on ESC (large colourful barrelshaped). Every ESC manufacture has already installed the right size caps for the leads on their ESC. The capacitors will get hotter because they have to work harder and will be destroyed over time. Ultimately they can overheat and pop/explode.

Having looked at the ESCs listed on George's page I can see no obvious differences in them to any other mainstream ESC from China. There's no problem with that - they will be perfectly reliable if used within their limits - but they will also be just as vulnerable to voltage spikes in the long run as they have always been. If there is something special about 4-Max's ESCs that protects them I would think George would be making a big deal out of it on his site, but that isn't the case. Before I lengthened the battery wires I'd want to understand what explicitly is different and why it protects the ESC from failure in the long term if used that way.

 

 

Edited by MattyB
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On 02/03/2022 at 17:43, Allan Bennett said:

I've been away for a while, but last week I ordered and received my A10 full kit, and the fuselage is well on its way to being structurally complete, with nacelle framing added today.  Motors and ESCs arrived from 4-Max today too.  

 

Having got this far I can see that my earlier suggestion of putting the fans at the front of the nacelles for better efficiency is impractical.  But the 50A ESCs supplied by 4-Max seem, in my view, too large to fit comfortably inside the nacelles.  I can see in his photos how Colin Low 2 has got them in, but nevertheless I'm going to extend the motor wires and install the ESCs somewhere inside the fuselage instead.  This will make them more accessible for my arthritic thumbs, and will also allow me to run the motor wires into the fuselage near the rear of the pylon, where they'll be even less visible.  

Hi Allan,

Yes our ESC are not the same as your average ESC.
Firstly they use a 32bit processor, unlike most of our competitors who have the cheaper and slower 16 bit processors.

This means our ESC's are more efficient and can deal better with high RPM motors as in EDF applications.
Secondly I have personally tested our ESC's with a battery length of 1M and have had zero problems. Our manufacturer has designed around the old problem buy better design and the use of better/more resilient components.

 

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It's coming on.  All structures built, but a lot of planing/sanding to do to get the final shape.  The only issue I've had so far is that I ran out of 3mm and 12mm balsa but have got three full 1.5mm sheets left over!  This is from the TN wood pack.  I laminated two strips of 1.5mm together to make the 3mm false leading edge for the wing.

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