X-Craft RC options

[subkraft]

Here's a pic of my hull in progress, trying to improve the shape , intend to add the saddle charges as integral part of hull.
As mentioned, this is the old Darnell hull. I've ben using the drawings out of the kemp book as reference and the casing looks a bit wide in proportion to the length to me...

[Kazzer]

Here you can see how the propeller has been pushed way out for the hull. It fouled the new dive planes I'd just installed. I thought I'd done something wrong when my new planes fouled, until I realised the whole shaft had shot forward from the impact, thanks to the neanderthal UPS driver.


As you can see here.









Here is the finished repair, with two lead weights that fell off during shipment.

I have been told by the UPS Rep that my claim is being paid, and I should receive a check for some $1500 shortly.

[Kazzer]

Today, I actually finished the repair of my X Craft. It wasn't easy, as there were a few more minor headaches. The push-rods had been bent back somehow and didn't fit to the WTC, and as I bent then back into position, one snapped apart. I put a brass sleeve over the joint and super-glued it into place as it was too difficult to solder. Once that sorted out, I returned to setting up the dive plane and rudder to work properly.

A pre-mission check told me all was well, so I painted up all the dings and scratches. I had a couple of weights come unglued, so I fixed them.

The model really is ready to put in the water now, so tomorrow, I'll take the cover off my pool mid-morning, and give her a trial run. I am a little worried that she'll need trimming, but I guess I can conquer that problem. And finally, UPS phoned they were cutting me a cheque for all the damage they did. I must say, it was hard work to fix and I earned the money!

[Kazzer]

After several successful dry runs, and mission check, it was time to remove the pool cover, scrape the leaves off, and chuck her in.

I revved her up in reverse and forward, ran the dive planes and rudder, and turned around to check I'd shut the door, (it's flippin' colder than a witches breast here) and when I turned back, there she was, plummeting to the bottom. The Titanic
Thankfully, I managed to grab her tail just before she slipped into the dark depths (we're in the 3' deep bit) and yanked her out.

An inspection revealed at least a quart of water had entered the cylinder. Can you believe that! Damn!

I drained it all out shook the livin' daylights out of it, and immediately stuck it over an a/c vent blowing warm air. It's still there now.

At the moment, I'm looking up new and unusual swear words, as, even though submariner swearing was part of my childhood education, I feel I need more today.

I think I found the culprit. There's a small nipple thing, dead center of the for'ard end-cap. I hadn't taken much notice of it, until when I tipped up the WTC, water ****ed out at one hell of a rate. It must have ****ed in at about the same speed. Now, what bloody idiot put that there? Why? :biggrin:

And why didn't I take a peep through it? I would have seen there was 1/8" diameter hole right through it?

Hopefully, tomorrow will be better. I could move my webcam so you could all see me making a hopefully better maiden voyage? Say 11am Eastern US time?

[Subculture]

Is the nipple the one with pipe attached here?-



I think that is a pipe for pressurizing the WTC slightly, ironically to check for leaks. Nigel should be able to tell you one way or another, or ask Bill.

[Kazzer]

Is the nipple the one with pipe attached here?-

[ATTACH=CONFIG]12626[/ATTACH]

I think that is a pipe for pressurizing the WTC slightly, ironically to check for leaks. Nigel should be able to tell you one way or another, or ask Bill.

It's on the for'ard end of the WTC.



It looks like a barb connector for plastic tube.

[Subculture]

Yes looks like it. Didn't you mention this before? I'm sure it's there for a purpose.

[Kazzer]

Yes looks like it. Didn't you mention this before? I'm sure it's there for a purpose.

I think I did somewhere.

Bill replied - "I think it is to pressurize the wtc by dealing it with a bung in a piece of silicon tubing".
I think I understand what he meant, but he sounds unsure. Did he ever actually run this boat?

Does one puff a breath of air into the tube to pressurise the WTC? It sounds like over kill again, and I really am concerned that if the tube fell off, we'd have another flood.

[Subculture]

He had it running at the October 2010 Dive-in. Can't think of any other reason for that nipple.

If the tubing is held on with a small zip tie it won't come loose.

[Kazzer]

He had it running at the October 2010 Dive-in. Can't think of any other reason for that nipple.

If the tubing is held on with a small zip tie it won't come loose.

I'm more concerned with the other end. Did they just ziptie that folded over? Or have a valve?

[Subculture]

I would just ziptie a bit of silicone tubing to the nipple, then blank off the other end with a piece of brass round, and zip tie that too.

I would also be inclined to test out the wtc in the bath or paddlign pool before committing it to the deep, at least for the first outing.

[Kazzer]

I would just ziptie a bit of silicone tubing to the nipple, then blank off the other end with a piece of brass round, and zip tie that too.

I would also be inclined to test out the wtc in the bath or paddling pool before committing it to the deep, at least for the first outing.

I'm almost tempted to rip out the nipple and replace it with a tire valve & housing. I could then simply pump a bit of air in with a bike pump without having all this 'stuff' lying around. Mr. M uses these in all Sub-drivers to do pressure test and relieve pressure after securing the end-caps.
There's no way I'm putting this beauty into the canal until it's had a few hours in the pool, and my trials are going to be in the shallow end too. That water is darned cold, and I'm not going in until my heater is running.

When I ran the motor, it looked like it really was scaled down in speed, and reverse was half speed.This baby is a slow-coach eh? Is that ESC programmable somehow?

[Subculture]

You could replace it with a tyre valve. Perhaps it was run that way to enable the cylinder to be checked when in situ. After all it's accessed from underneath the boat, so not easy to get at once the cylinder is installed in the boat.

This boat is no skipjack I'm afraid, but then the originals weren't fast boats, so speed is about scale. You will get a lot of endurance with this set-up.

It's an MFA 500 size motor in that boat, and I would hazard a guess that it's 6:1 reduction. It's a slow turning motor doing about 9000RPM at 7.2 volts, so you should see about 1500RPM at the prop unloaded, with a lot of torque.

http://www.mfacomodrills.com/gearboxes/919d_series.html

If you want a little more speed, then you have a couple of choices. Fit a hotter 500 size motor, a prop with more blade area and pitch (one of prop shop's 3-blade steam props for instance 1.5x pitch), or increase the voltage to 12 volts. I'd advise caution with the latter- the drive motor and pump is fine at 12 volts, but the ESC may not be, so I'd advise checking the spec on that one.

I can't give you any details on the Ripmax ESC, as I've never used one. AFAIK they're plug and play, but Ripmax should be able to send you instructions of some kind if you email them with the model number- http://www2.ripmax.net

Half speed reverse doesn't sound good- this is quite a heavy boat and you want full reverse to help it stop. You could swap the controller out with one of your Mtroniks, but make sure you disable the BEC on the controller as the boat has a dedicated BEC already.

[Kazzer]

Good stuff to ponder Andy. You have a good grasp of this model.
I did a water test in the bath (pool is frozen - again) and initially all the end-caps leaked. I guess the thumb screw nuts weren't tight enough. I needed to tighten them a little more with grips.
The second immersion showed a leak around the shaft housing. I think the seal must have been broken when UPS kicked it.
I soon fixed that with some CA and baking soda.

Tomorrow, the WTC will be installed in the boat and on Thursday the weather will be good, so I'll pop her in the pool!

Next project, to get my TT Neptune running properly. She's a sinker at the moment, and I need to check for leaks etc. Another trip to the bath.

[Subculture]

The rods are sealed against the endcaps in a somewhat unconventional manner- little pieces of silicone tubing which compress up axially on the inside face as the endcap is tightened.

I prefer the seal on the outside personally, or better still run the rods externally, then you don't have to seal them at all.

Not sure about the shaft seal, I think it was a piece of brass tubing with a simmering type seal at one end and probably a bearing pressed in behind the seal to support the shaft. Don't know how it was originally fixed to the endcap, but I wouldn't trust cyano long term.