LH 253

G'day all, this is my first post although I have searched through this site many times before for info on different things.

After much searching there seems to be nothing anywhere on anyone putting a nitro engine in the infamous dodgy NQD hydro hull. After I bought one through Ebay and realised it had similar (if not the same) tiny electric engines as the small version, I had a look at a spare Hyper.21 I had and reckoned it would fit. Me being a person that would do something because no one else has, was my green light to try this...

I built a wooden frame to hold the motor etc. and to give it some strangth. I made the motor mounts out of 1mm aluminium and an old fanbelt. The tank I made to shape out of tin then silver soldered. The rudder servo sits flat in the back and actuates a 'L' pivot on the right, to the rudder. The throttle servo sits to the right of the air filter. Yes I'm using an air filter as I'm used to tuning cars etc. with a filter and it aids in 'sucking' up fuel from the tank. The exhaust is just copper tube for now with a tube to pressurise the fuel tank. There is no room for a radio box so I mounted the reciever batt on the left intergrating 'some kind' of heat shield (tin) and used an old plastic jar cable-tied to an aluminium plate to house the reciever and connections. The strut and rudder were the most difficult as the rear is so thin and is split incorporating the hull top and bottom seal. Too weak to attach to the rear and would bugger the seal. So, I made a flat plate out of 2mm stainless sheet with a bent edge to sit under the rear and attach to the bottom/floor section. Then I made 2 kind-of 'L' sections in stainless with a slight 'S' in them so the top section was almost together hfor the upright and spaced out at the bottom where it's silver soldered to the bottom plate. I silver soldered a plate across the gap to attach the (bought one) rudder to. I made the strut out of copper tubing cut and shrunk to the same size as the brass bushes and the upright from the same kind of tube flattened out. (Much easier than stainless and will re-do in stainless if the copper isn't strong enough) The flex cable is out of an old pedestal drill and I made a cup with a thread on top to attach the collet to and grub screws to hold onto the clutch bell. I made a turn fin out of stainless aswell, sharpened and attached with a stainless bracket with a wood internal brace. And yes, it all fits under the top/scoop. To hold it down, I made a post out of brass tube with a little copper piece and part of a cig lighter spring so I only have to push the top down until it clicks.




Pictures say a thousand words so here goes-



















I have sealed the top and bottom with a bit of silicone and done a bath float test. Not bad, though it looks tail heavy. Appears to sit in the water nuch the same as the full scale boats so I have fingers crossed... I have not been able to give it a run at a local pond just yet because it's been WAAAY too windy and choppy.

Once I've given it a run I'll let you's know how it went.

Hopefully this may help those people who have said they would put a nitro engine in one of these, even though I can't find anything anywhere to suggest they may have actually done it.
I have found that those that have gone with upgraded electrics and motors still haven't been very impressed (please correct me if I'm wrong) so maybe this could be something for a spare nitro engine to put into.

If your reading this, Cheers.

boatnut

  Man, talk about  mostly home built.  I have to hand it to you with so many ways to build your own parts.
  You must be a long way from a hobby shop, or the shop is upset with you for fabricating your own.
 A  great job, although the weight factor will cut speed, it will be a fun boat.
Waiting tohere how it runs. I hope it's not to heavy to get up on plane,

GOOD  LUCK

misshydro

Been there done thats..That thing is a tank..had a hard time getting to get on plane too...

LH 253

My 'local' hobby shop has nothing to do with boats or parts except for 1x AU$900+ deep vee gas boat. The cheapest I could find for a strut and rudder assembly was over AU$200. And it still wouldn't bolt up so I'd need a plate anyway. I like playing around like this and so far I only had to buy the rudder and a heap of bolts, nuts etc. All up- for the boat, engine, rudder, and other bits, (had stuff like the stainless sheet and copper tube already) +a cheap 2.4ghz radio, it's cost under AU$250 and I've had a ball doing it too. Worst comes to worst, I can put the engine straight into my buggy.

I've had a look around on the net and I gather the engine is 1.9hp possibly even the 2.5hp one! Hopefully it will have enough 'beans' to get it up, but not too much to destroy itself. Had my scratchbuilt adapter for the clutch bell to collet come loose and f***** a flex cable already. Round 2 seems much better.

misshydro have you done this to a NQD hull? Any suggestions? And yes it weighs a ton.

If I made under the rear at the sides bigger would it help much with rear bouyancy or would it be just more drag?

This is my first nitro boat so EVERYTHING is an experiment.

Cheers.

LH 253

Went and tested it this afternoon for the first time at a local pond.

CRAP!  In short, IT SANK!

All that was left above the waterline was what you can see here.  Just the nose.  Didn't think to take a photo at the time...
 
 


 Fortunately I had the 'Little Red Brick' with me...
 
 

It started well but just wouldn't speed up.  The prop was cavitating like mad and it sounded like something was slipping.  It was cruising slowly and turning well for about 3 laps but the back end looked like it was sinking.  That's when I decided to bring it in.  The back end dropped heaps in the last turn and then wouldn't straighten up.  The engine stalled and before I could say "Uh-Oh" the nose came up, the back went down and it was show over.  The pond is only shallow but my rudder was touching the bottom so it wasn't going to drift to the edge.  AAARGH!  The idea of wading through duck s#!t to retrieve the boat was not a pleasant thought.  My mate was with me and was 'putting around' with the little brick.  He managed to start to push my 'yellow submarine' before the brick flipped over!  Great!  2x dead boats!  Middle of the pond and duck s#!t everywhere around the edge!  My mate found a huge stick and when the light breeze blew the brick close enough, he dragged it in.  I had a go and after 20-odd hits got the yellow submarine to the edge and pulled it out of the water.  Electrics looked good, not filled with water, throttle OK, Rudder dead and stuck hard right.  Could be why it wouldn't straighten up...  Ran the little brick until it was flat (crept up on some ducks couldn't say chased) packed up and headed home.

Wasn't as bad as it could've been, it didn't catch fire or crash and sink completely...

Here's what I found after pulling apart the boat to check everything.  The waterproofed rudder servo had a crack in it near the mount!  Explains why it died- the circuit got wet and fried an IC.
 
 
 
After having a good look over everything and seeing if there were any other problems, I filled the engine with RP7, drained and fired it up.  All good.  I checked the collet.  Tight.  That wasn't the slipping.  Had a look at the clutch bell and noticed it was a little 'blued'.

I'm thinking my prop is too big and needs to be lowered more.
Any HELPFUL suggestions would be greatly appreciated.

Cheers.