Frank's Horizon Hobbies RV4 30cc build

[Frank v B]

My next assignment from John's Hobbies is the Horizon Hobbies 30cc RV 4 ARF.  It is huge.

The motor is an E-FLITE 180 195 KV, A 3000 watt unit... or as EdEdge would say "...starting to get interesting".  There is a washing machine somewhere missing a motor!

I will pick it up on Saturday and start the assembly work.
https://www.horizonhobby.com/vans-rv-4-30cc-p-han4885


Frank

[Frank v B]

Just picked up the stuff.

Correction on the motor.  Check these stats out.

- E-Flite Power 360
- 12S power (44.4 volts!)
- 24x10" prop
- 130 amp continuous
- 6000 watts.  Sorry, did I wake you EdEdge?
- 43.7 ounces

There must be a Tesla missing a drive motor.

The plane is still in the car.  Will bring it in when I park the car on the driveway tonight.  Will post some photos of the motor and the plane box tomorrow.  Have to get my stuff ready for Bruce's Cub day tomorrow.  Remember to meet us at Tim's Woodbine at 9:30 am.  It should be a blast.

Here are the photos.  For a comparison is a Power 46 both in the box and out of the box.  The big motor is 8 HP!

Frank

[Frank v B]

Step 1- install the motor.  This motor is twice the power so there will be a lot of reinforcing required.  I install the motor first because this way there are no tail feathers and landing gear sticking out to make it hard to handle.

This plane has an integral motor box.  For an electric motor, a second box is added to make the prop stick out in right place.

To reinforce both boxes, I painted a strip of 20 minute epoxy on the motor box then stretched Kevlar thread on the glue and wrapped about four turns.  This holds the corners together so they cannot come apart outward.  Then wrapped waxed paper around it and held it with one 64 rubber band.

There are two wraps on the integral box and one on the electric extension box.  This Kevlar is absolutely bullet proof once cured.

From here on in the approach can best be described as:

Assemble the front of the plane so it holds together.  Then take it apart and add carbon, fibreglass and Kevlar in appropriate places to strengthen it

This avoids the problem of putting strength in the wrong places that makes it difficult to assemble the plane accurately.

Photo 4 shows the roll of Kevlar thread.  It behaves like silk
Photo 6 shows me wrapping the thread around the box.

[Frank v B]

Installing the motor:

2 challenges:
- the larger motor's "X" mount is bigger than the motor box
- the larger motor is a lot longer than the one it was designed for.  The firewall has to move back about 3/4" to make the prop/spinner stick properly out of the nose cone.

Approach-
- lengthen the slots so the motor/firewall can move back.  Old slots- photo 07 with the slot enlargements penned in.  Photo 08 shows the cutting with a razor saw. Photo 12 is of the finished slots. 
- the length of the slots was determined by measuring the length of the motor on a stick (paint brush) as in photo 10.  Then adding the nose cone and measure the depth of the firewall.  The mark on the stick is in line with the front of the cowl.

To come:
- attach the motor to the firewall.  Some significant cutting is required to allow the X mount to clear the motor box.  This will weaken the motor mount significantly
- attach the whole nose cone
- make a 1/8" spacer out of balsa wood so the spinner back plate can rest on the nose cone and automatically align it.
- take everything apart and strengthen the hell out of it.  Without strengthening with Fibreglass, Carbon fibre and Kevlar this motor mount would probably fail at anything above half throttle.

Frank

[Frank v B]

Here is a picture of what the double motor box looks like attached to the fuse.
You can see the yellow wraps of Kevlar epoxied to both motor boxes.