Brad

What I really love about the dragon is this.. I have been a HUGE fan of Tolkiens , The Hobbit, and The Lord Of The Rings since reading them in high school.  This dragon to me is so much in that style of drawing.. Really appreciate it.

I was so busy looking at it I didn't realize it was electric until now.

How long did it take?  I bought the kit in 2018, finished it earlier this year.  I worked on it about half time during that six year period (I'm retired); so, it took about three years.

Here is how I installed the electric power setup:

The basic hardware is a Hacker Q100-8M motor, an Opto Master Spin 220 ESC, and a 32x10 prop.  I'm using a pair of 6S 10,000 mAh batteries in series, with EC-8 connectors.  The weight of the motor, batteries, and ESC is 10 lb 4 oz.  This is about the same as a G62 with a reduction drive and 16 oz. of gasoline.

The Hacker support folks in Germany have been very helpful with questions I've had about their hardware.

How to package all that hardware into the D.VII fuselage?  I placed the firewall way forward in the fuse, as the electric motor is so much shorter than a gas engine.  In this drawing, the Hacker motor is superimposed on the GTM plan.  I've colored the new firewall red;  the gas-engine firewall location is colored orange.

I built a pair of LiPo battery holders, each of which will hold a 6S 10,000 mAh battery and a NiMH receiver battery.  The batteries are held in place with Velcro straps.

I wanted to put the big LiPo's as far forward as possible.  The battery holders are screwed to the back of the firewall, so that the batteries are in a vertical position.  

In this picture, I've put one of the holders on the side of the fuse to illustrate its location inside the fuse.  The batteries comfortably fit inside all the pieces of the radiator and cowling.

The motor is a tight fit inside the radiator shell and the chin fiberglass.  I built an accurate wood mockup of the Hacker motor, so that I could precisely place the motor during construction of the from of the fuse.  In the picture, I've colored the wood motor purple.

In this picture, the camera is inside the fuse at the level of the cockpit -- looking forward to the firewall.  You can see the two battery holders, with the ESC mounted between them:

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So, how do I access the batteries?

There are three things to note in this picture.

1.  The two panels at each side of the motor (indicated with orange arrows) are easily removable.  Each is held in place with two Fokker nuts.  BTW, I made these panels of fiberglass, using the male mold technique.  I constructed the balsa male mold in situ  on the fuse and used Saran wrap as a parting agent; I removed the balsa male mold after doing the fiberglass work. This method guarantees that the panels are a perfect fit against the radiator shell.  If you're not an expert sheet-metal worker, I think it would be very difficult to get such a good fit with aluminum.

2.  There are two pipes coming out of the radiator (indicated with blue arrows).  The lower one is not physically connected to the engine, just butts up against it.  They are held in place on the radiator shell by neodymium magnets.  Again, easily removable.

3.  The fake engine is held in place with eight 1/2" neodymium magnets, which are on the bottom of two cylinders; this will be illustrated in another photo.  The Mercedes engine pops out of its mounts with a little effort.

It takes less than 5 minutes to remove all the structures and access the batteries.

This is a picture of the two transverse struts containing the magnets that hold the fake engine in place; they are indicated with orange arrows.  You'll notice that there is a raised rim around each circular mount, to positively locate the two cylinders.

The two boxes holding the big LiPo's are indicated with red arrows (batteries aren't present).  You can see the two Velcro straps holding the batteries in place;  the straps anchor on the fore engine mounting strut.

With 10 lb of battery and motor mounted so far forward, it took only 2.5 lb of lead to balance the plane.  The box holding the lead is indicated with the blue arrow.

One last issue remains.  The motor can handle 8,000 watts, which is over 10 horsepower (!) -- three times the power of my big table saw.  As a safety precaution, I don't want to arm the batteries until the plane is ready to head out to the runway and take off.  This means that I had to find a way to connect/disconnect the big LiPo's after the fake motor and fuse panels were back in place.

There were two alternatives.  Hacker sells a magnetic switch to do the job.  However, it entails some disadvantages -- it is expensive, weighs a few ounces, and adds complexity to an already complex setup.  The second choice was to make the connection between batteries and ESC accessible through a hatch, which can can be accessed after the fake motor etc. are in place.  I chose the latter.

This photo shows two open access hatches (BTW, all hatches on both fuse side panels are functional, using magnetic latches).  

The fore hatch, which is big enough to get my hand through, provides access to the cable from the LiPo's and the cable from the ESC;  in this picture, one of the cables is hanging out of the hatch.  I connect the batteries and ESC just before takeoff and disconnect them immediately after landing.

The aft hatch contains the switches for the two receiver batteries.

Hope this answers your questions.

Charlie

Charlie.

Thank you very much for a great explanation.

With regard to Arming the Lipos. If you use a separate battery(ies) to power the receiver then with the the Receiver switched OFF, you can connect the Lipos, but the motor cannot start until the Receiver is turned on.

I do that for safety reasons as well as avoiding using a BEC with big Batteries.

 I use a small extension wire from the ESC to the Receiver with  the RED wire removed.

Alan

I am aware of that.  However, at some level I just don't trust all these electronic devices -- switches, and printed circuit boards in receiver, ESC, and now apparently in "smart" LiPo's.  That's excluding the fancy Hacker electronic/magnetic switch, which I avoided using. Too many places for something to go wrong.  Especially with a 10.7 HP electric motor powering a 32 inch saw blade.  So, I wanted a separate arming/disarming step for the big batteries. Just to be VERY safe...

Impressive details all around.