Scott's DF21 Mk2

**Scott T** · 01-11-2011, 03:52 AM

Set up will be:

Castle 1717 Air (1500 kV)
YGE Navy 155 ESC
XPS 65C 6S1P lipos
Speedmaster hardware
FE.com motor mount
Futaba FASST radio

**nobbiworld** · 01-11-2011, 05:30 AM

Lots of new toys. Good to see the classes growing. Should be a great year. Steve

**Scott T** · 05-31-2011, 07:59 AM

Have been able to make some progress on this hull recently. First pic is of all the goodies to go on/in the boat.

Second shot shows the motor mounted in the mount. The 1717 has some end play, so I'm using a thrust bearing. The shaft is long enough that the thrust bearing can press on the motor mount and still have plenty of shaft for the coupler. It's all quite neat.

Next was mounting the strut. I've offset it about 3/32" to the starboard to counteract prop walk. I do this on most of my monos and it works well. The strut was shimmed 3mm off the workbench, holes marked, and the strut bolted to the hull. This should provide a good starting point.

Attached Files

**Scott T** · 05-31-2011, 08:07 AM

Mounting the rudder proved a difficult task. I chose a 1" Speedmaster rudder, but the transom of the boat is quite small. The mounting bracket for the rudder is quite large and it took up a lot of space on the transom. The trim tabs weren't going to fit without some serious modifications.

The strut picture above shows the marking out of the rudder and tabs - not good..... I cut the tabs in half (they're quite big anyway) and drilled some new mounting holes for them. I was about to grind a corner off the starboard tab to make it all fit, and decided it was all too hard. I had a 1" tapered speedmaster rudder and it has a much smaller mounting bracket, but the blade is of a similar size. So my original rudder went back in the packet and the tapered rudder is going on. Everything fits much better now.

Attached Files

**Scott T** · 05-31-2011, 08:16 AM

The internal rails were trimmed down because I plan on making a plate for the ESC and mounting it across the starboard rail and the hull.

I made up a spacer block out of some carbon sheet to put the rudder back further (more in line with the prop). Tabs were mounted and the pushrod aligned so I could start on the servo mount.

The servo mount is a 1/8" plywood tray that is held in with 4 screws. I like to be able to remove the tray to get into the shaft area if I ever need to. It works well on my DF33. Some localised thickening to 3/16" underneath will add some strength for the servo screws. The receiver will also be mounted on this plate. I'm happy with the result, it all lined up nicely.

Attached Files

**raptor347** · 05-31-2011, 11:51 AM

Looking good Scott. I've got one here, just haven't gotten around to it yet. Nobody to race those cell counts with around here, so it's get built as a SAW/2-lap boat.

**Scott T** · 06-01-2011, 07:51 AM

Thanks Brian. They're a great looking hull and 6S will pack a big punch! The only downside is the composite transom doubler - good for longevity, but bad for installing blind nuts!

**Scott T** · 06-01-2011, 08:35 AM

I marked the potential CG locations at 30% and 33% and put in the major items. I moved the motor and battery until I was happy with their positions and marked it out. There's plenty of room if I need to adjust the CG later on, but I was looking to get a good place for the motor.

With the motor located, I drilled the holes for the mount. The motor angle was adjusted so that a 3/16 drill bit touched the floor and inch or so ahead of the transom. This will give a nice curve to the stuffing tube and ensures the tube is level where it leaves the hull, for a neat entry into the strut. This boat will have a flooded brass stuffing box, but that's a job for this weekend.

Attached Files

**Scott T** · 06-11-2011, 12:38 AM

Flooded stuffing box is done. It's simply a piece of 9/16" brass for the outer tube and 1/4" brass for the inner tube. The two are sealed at the front with a piece of plywood epoxied in. This allows plenty of adjustment at the strut and good support for the shaft. The alignment of the flex shaft came out really nicely, so everything will run smooth.

Today I added trays for the battery and speed control. We only run 1P, so the tray is only sized to suit, with some allowance laterally for balance adjustments. The notches in the tray are for Velcro straps that will add the the Velcro to be added on top of the tray. The ESC will simply be held in with Velcro.

An extra support was also added at the front of the stuffing box. The boat will be put aside overnight now, and I'll do some work on the electronics.

Attached Files

**jwt** · 06-12-2011, 05:00 AM

Stuffing Box

Scott

i thought you were going to solder this stuffing box this time,,,

tms

**Scott T** · 06-12-2011, 08:15 AM

Hey John, I decided my soldering equipment wasn't up to the job. I did spend a while soldering up the ESC and safety loop parts today (iron is good enough for that). This one has all Castle 6.5mm plugs.

I also fitted the cooling jacket to the 1717. Being the Air version, it has flat spots on the fins that need to be filled. I used one of Andrew's Kuhlers (meant for a 1900 Neu) and some o-rings I sourced. The fins were spaced perfectly fo the o-rings to butt up hard against the ends of the Kuhler and keeping it centred on the motor. A liberal application of silicon before the o-rings were brought against the Kuhler sealed each end, and the flat spots on the fins. Sounds rough, but it came out quite neat. I will pressure test for leaks before use though.

Attached Files

**Scott T** · 07-04-2011, 01:47 AM

Plywood trays for the battery and ESC were installed next. Velcro straps wrap under the battery tray, and should give plenty of restraint during the inevitable crashes.....

Attached Files

**Scott T** · 07-04-2011, 01:52 AM

The boat is basically complete now. Just need to install the flotation (pool noodles), charge everything up and let it rip! Slight delay in my plans though, since my baby daughter arrived 4 weeks early! So priorities have changed a bit. My JAE build has also halted for now. I've got a few weeks off work though, so I might sneek out of the house for a test when the missus is asleep

Attached Files

**Scott T** · 07-04-2011, 01:58 AM

The insides. RX pack is missing from these pics, which goes on the port side in front of the switch. Still needs to be stickered, but those haven't arrived yet.

Attached Files

Scott's DF21 Mk2

Scott's DF21 Mk2

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