Hydro-bat by Vic Smeed: engine probs

Cool Build , had to google the image to get in my mind the outset ..
Bee sweet when done .

That's the one!! I used ordinary wood glue and let it dry for 24h each time.

getback wrote:Cool Build , had to google the image to get in my mind the outset ..
Bee sweet when done .

Yes sir! Lieven finds and builds the most interesting models I've ever seen. I wish I had his snow-car here for running after a big storm that's due to hit this region early tomorrow morning.

This little boat looks like a lot of fun! I'll bet it skips-along like a hydro!

roddie wrote:

getback wrote:Cool Build , had to google the image to get in my mind the outset ..
Bee sweet when done .

Yes sir! Lieven finds and builds the most interesting models I've ever seen. I wish I had his snow-car here for running after a big storm that's due to hit this region early tomorrow morning.

This little boat looks like a lot of fun! I'll bet it skips-along like a hydro!

Tomorrow would be a good day for a snow car 3+ inches predicted tonight.

Phil

Thanks for your encouraging posts. We havent seen snow yet this year. The snow plane stays in the cupboard for the moment.

I checked out the pylon on the plan with the engine to be fitted. I will increase the height by 5mm so the prop clears the deck. I will also cut a rectangular hole to partly insert the fuel tank in the plywood.



I'm planning to modify the pylon a bit. Originally, the 3mm firewall is just stuck onto the pylon's edge. I want to make an 8mm firewall with a slot to improve the bond between both pieces as is shown on the drawing of the Graupner motor mount for their small gliders (nr 3).

Oh, great! Just what I need. Another plans site to spend hours searching and downloading plans....

The Time-Crunched Mark

THE PYLON

The pylon was cut out from 3mm ply. The fire wall is 5,5mm thick. The tank fits in the rectangular hole. The fuel feed pipe sticks through the fire wall. The parts were epoxied together and epoxied in the frame. I dry mounted tank and engine and the prop should have enough clearance. Next is the bottom planking.

Some pictures

1/2A Nut wrote:Nice I like 1/2A boats, 2 weeks ago I finished one with a .07 engine. Waiting on good weather to test it. Has a small converted car engine in it a SH 07 with a Profi .8cc tuned pipe. Air boats are fun you can wet cut grass and run them in the back yard. Hope to hit 60 mph

Wow! 1/2A Nut, that is really sweet, looks fast standing still and excellent workmanship!

OVERLORD wrote:THE PYLON The pylon was cut out from 3mm ply. The fire wall is 5,5mm thick. The tank fits in the rectangular hole. The fuel feed pipe sticks through the fire wall. The parts were epoxied together and epoxied in the frame. I dry mounted tank and engine and the prop should have enough clearance. Next is the bottom planking.

Overlord, that is a really neat looking airboat, build looking good, especially the hotter Cox engine reedie installation, streamlined versus the simpler rectangular Dumas 1/2-A swamp buggy I built in high school almost 50 years ago.

Thanks for the encouragements. That's a good looking rigger Brad. Did you make the rudder?

I was and still am busy covering the frame with the bottom panels. The centre part is easy with the grain across. The bottom sides are more difficult to trace first and than to glue in place. The pattern drawn by Vic Smeed fits but on some areas, there's a difference of 0,5 mm to 0,75 mm. I corrected the pattern by adding bits if paper with sticky tape while the pattern was actually on the frames. Glueing of the panel is done in 3 stages because the panels are at the same time twisted and curved wiith the grain running lengthwise. The edge that meets the central bottom panel needs to be beveled with a plane. The port panel is almost completely glued. The front part is the hardest and before fixing that part, I will first cut out the other panel and stick that on just to prevent twisting of the hull.

Looking great Lieven! Fitting those side-hull pieces is definitely tricky. I remember that from when I built my Dumas DV-10/Short-Stuff.. and that was a die-cut kit. I ended up using some auto-body filler in a few areas, and I too.. needed to even-out some areas with a surface-plane. I'm pretty sure that I applied several coats of auto-body primer; sanding between coats.. and used epoxy-paint for the finish. That model is electric-powered.. but the epoxy-paint would probably be fine with glow-fuel. The entire interior framework was brushed/sealed with epoxy glue. Is there anything in a construction-article regarding sealing the interior of the Hydro-Bat?

Have you considered adding a ballast-hold to the hull; where you've raised the height of the pylon slightly and will be carrying a heavier initial fuel payload, as compared to a Babe Bee? An automotive wheel-balancing weight-strip could fit snugly into a fore-aft channel in the center of the hull and be easily repositioned via a small hatch and needle-nose pliers.. for adjusting how the boat planes-out on the water as well.

Coming along very nicely. I have had the plans for quite a while myself, but have just not gotten to it. One day I might have the chance.

roddie wrote:Looking great Lieven! Fitting those side-hull pieces is definitely tricky. I remember that from when I built my Dumas DV-10/Short-Stuff.. and that was a die-cut kit. I ended up using some auto-body filler in a few areas, and I too.. needed to even-out some areas with a surface-plane. I'm pretty sure that I applied several coats of auto-body primer; sanding between coats.. and used epoxy-paint for the finish. That model is electric-powered.. but the epoxy-paint would probably be fine with glow-fuel. The entire interior framework was brushed/sealed with epoxy glue. Is there anything in a construction-article regarding sealing the interior of the Hydro-Bat?

Have you considered adding a ballast-hold to the hull; where you've raised the height of the pylon slightly and will be carrying a heavier initial fuel payload, as compared to a Babe Bee? An automotive wheel-balancing weight-strip could fit snugly into a fore-aft channel in the center of the hull and be easily repositioned via a small hatch and needle-nose pliers.. for adjusting how the boat planes-out on the water as well.

Roddie, what ballast or balancing is concerned, the article says to move the RC batteries more forward or aft in the centre compartiment. I'm not worried about this alleged extra weight. Vic Smeed mentiones it could be powered by a 09 as well. What I will mount is an aluminium strip in the forward edge that will act as a front bumper.

I got the bottom ready but the last bit was the hardest to glue and to keep in place. On one side I had to cut some grooves to help the wood to bend nicely. Also, on that same side I have to fill a narrow gap with a tiny strip of balsa.









Hi New, it's a habit I'm also familiar with. What helps in such a case is when the plans were actually bought. Then I like to see them transformed in a model sooner or later.

remembered to change the post title

Dang that looks good. This is killing me!

Geez yes... looking great Lieven! Love the "pinning".. reminds me of how you formed the "Cauldron's" engine cowling.. and several other builds that you've meticulously mastered. I wasn't aware that that this model was radio-controlled. I thought that it was a "free-runner" or tethered-design.. I'll admit that I did have some RC ideas to pitch to you though.

Look into the newer-technology receiver-batteries. There's some LiFe packs that are tiny... and would be perfect for this application. Combined with a nano-servo for the rudder... you'd have a micro-weight radio. I'm sure you can locate a feather-weight receiver to do the job.

Thanks guys. Only the batteries have any weight. The small servo is very light and the 2.4 gHz receiver even lighter. Vic Smeed's model had a weight of 8 to 9 Oz. That's 230 to 250g. At this stage, it weights 81g.

For sealing, the article says to dope and cover in tissue the hull, then paint. I was thinking of doping the Inside and outside, then to coat with PU varnish all with sanding in between. I like to finish the model with Oracover.

OVERLORD wrote:Thanks guys. Only the batteries have any weight. The small servo is very light and the 2.4 gHz receiver even lighter. Vic Smeed's model had a weight of 8 to 9 Oz. That's 230 to 250g. At this stage, it weights 81g.

For sealing, the article says to dope and cover in tissue the hull, then paint. I was thinking of doping the Inside and outside, then to coat with PU varnish all with sanding in between. I like to finish the model with Oracover.

You may remember I bought a Hobbico 200mAh 6.6V 1C LiFe receiver battery a few years ago. Its weight is 15gr. It may require a regulator to drop the voltage to a safer 6V though. It's a TINY battery-pack...

See the below photo for a size-reference on the battery..



That's 130gr........ along with a Babe Bee engine, x4 nano-servos and 6ch receiver. I'm sure that your model could finish-out at well-under 200gr. and maybe even close to 150gr.

That's a lightweight battery. I have a 1600 mAh battery and that weights about 100g. I had a look at the article again and noticed what I said about the model's weight is not correct. The 8 to 9 oz refers to the total weight of the RC gear. When I pile up the boat, servo, receiver, battery, engine and tank, the weight is at 270g for the moment.

A  small update. I'm working on the rudder and the fin. I decided to use a sheet of stainless steel. For that I bought a paint scraper at the DIY.



The rudder blade and the fin were cut out with a Dremel tool. For the rudder stock, i used a 2mm push rod with M2 thread on one end, cut to size. This was then silver soldered to the rudder blade. It looks a lot better when cleaned up!!





For the tube I used a piece of square carbon tube, epoxied to the transom. The 2mm rudder stock fits in there without play. The fact tht it's square makes it easy to glue and to keep in place.





To fix the fin, I just cut the bottom hull and inserted the fin with époxy.





I'm waiting for some M2 nuts to arrive to fix the rudder horn. Then, the deck can be glued on.

Very nice Lieven! You always engineer your models.. I love that! Did you cut a SS rudder horn too? It would be nice to able to braze it on.. but that might distort /melt the carbon tube? Apparently CF tube is resistant to water exposure? If it can be easily-detached from the transom.. and horn brazed, it would be a solid no-slip link. Install a brass flat-washer followed by the M2 nuts first, to establish a bearing. Double-nut the m2's then jig the assembly for brazing the horn on, near the top. A horn need only be a strip approx. 6mm x 25mm (tab) with holes drilled on opposing ends for the shaft and a clevis/pushrod.

If you want to retain the gluing integrity of a square tube to the transom, you could opt to go all brass.. with a round-tube sleeve running inside it.

I'm sure whatever you come up with, will be a functional work of art. It always is!

Very nice craftmanship, watching with interest.
I have also considered building this airboat, or the Swamp Buggy, but finding a place to navigate is not obvious due to the noise.