Vettster

Curious to see if anyone would be interested in a Turbine Powered water jet. I know I am cause I spent the last 3 winters building this one
But what about the general jet public.. This is more than a Water Jet, it can also be flown from soft snow and from green dry grass. Funny thing is it doesn't like wet damp grass. Seems to have a capillary attraction thing going, That is till I waxed the bottom and then it was as slick as can be. lol

So what you see in the photos is the porotype. Its prop driven for now, but is built to take a small 80-100N turbine. The motor mount will accommodate prop or turbine with minimal modifications. Im currently testing on a 10 cell setup, but will soon be putting a 100N turbine in it. Its 100% Epoxy construction with lots of CF.

Specs..
Full flying tail.
Length 72"
WS 54"
Take off weight Electric.. 22lbs This will be reduced in the future. Aiming for 19-20lbs

I'm Just a garage shop builder.. would appreciate honest and constructive opinions

Thanks!

Trevor

airwolf81

My Feedback: (12)

Very interesting project I actually like it. How would the the vertical mount be reinforced to endure it does not come off with turbine power.

interested in the design.

Vettster

Thanks Airwolf. I considered your question very seriously during the design phase. The Vert stab has 3 connection points.
First is the 1" CF tube that slides into the fuse and is clamped.
Second there is a hard mount for a large machine screw at the front of the vert stab
Third.. there are 2 bolts at the rear with a bolt on either side.
She's pretty secure.

airwolf81

My Feedback: (12)

very nice. I was a little concerned but seeing this looks like it’s very well taken care of.

how are the flights on so far ??

ravill

My Feedback: (11)

I want one!!!

Ret. SECRET AGENT

I remember when these "North Star's"

were quite popular, glad to see them making a comeback.

mauryr

Hey Vettster,
I'd consider putting a dowel in the CF tube if you're clamping on it, cf tubes are pretty ****ty at bearing that kind of compression loads and you may easily crack it imho

Vettster

. Yes Laddie did a great job designing the North Star. He helped me with advise during my building of the WETJET. He is only 1hr from me and I promised to let him fly it one day.

[QUOTE=mauryr;12688955]Hey Vettster,
I'd consider putting a dowel in the CF tube if you're clamping on it, cf tubes are pretty ****ty at bearing that kind of compression loads and you may easily crack it imho[/Qimho

Good tip.. thanks. If only in the clamping area.

ravill

My Feedback: (11)

Once you iron out all the kinks, I'll be one of your first buyers!

Can't wait to see it!

Vettster

Thanks ravill.. I haven't done much RC stuff in the past couple of years as I've got a major reno going on that I'm working on myself. Good news is its winding down and when the cooler days get here I'll be able to head back into the shop and not come out again till the spring I hope to pull a couple of planes by then, and make them much lighter in the process as many Ideas that I had in the prototype will be eliminated. I wont be using the Honeycomb looking stuff anymore, but rather substituting it with aero cell? (Cant remember the name, B1 Bob uses it all the time) By no means am I trying to make a living out of selling the WETJET.. but I wouldn't mind selling one or two every now and then.

invertmast

My Feedback: (23)

Thats a great looking airplane.

get rid of that soric and replace it with a airex/rohacell core or balse and you’ll be able to shave 20-30% of your layup weight. The stuff is nice to work with, but is heavy.

Vettster

Thanks Invertnmast.. Yes I agree 100% Airex is the way to go. Unfortunately for the prototype I didn't make the switch in time. I realized that the Soric is nothing more than a giant sponge for holding a ton of extra resin.
What layup sequence would you use.. 2oz, 4mm airex, 3oz ??

invertmast

My Feedback: (23)

that would produce a tank of an airplane, strength and weight wise. LoL

i would do 2 layers of 1.4oz, 2mm in high stress area’s (wings, bottom of the fuse vertical tail, etc) 1.2mm on the rest and then a final layer of 1.4oz with carbon where needed.

Vettster

Sounds good.. Now the hunt for the Airex or what ever its called here. Wayyy to expensive to buy from the US. Shipping is just stupid for what adds up to AIR!! I bought some for another project a couple years back.. but think I can remember its name or where I bought it LOL

Vettster

So.. Here its called Divinycell And the thinnest I can get it is 3.2mm or 1/8. Where are you guys getting it in the states. I might have to go that route in order to get thinner sizes.
https://www.aircraftspruce.ca/catalo...nycellfoam.php

invertmast

My Feedback: (23)

i have to import mine, no one in the us sells airex or rohacell. It ran me about $250 in shipping and import taxes the last time i ordered some about 5 years ago.

alasdair

In 2004 John Campbell built a Northstar, scaled up one and a half times to a span of 66 inches, powered by an ASP 108 and it flew majestically, but went home for “improvements”.

It reappeared at Loch Tay in 2005 with a turbine engine bolted on top, and the single fin replaced by a pair of fins to support the tailplane, and a plywood bottom. The turbine slowly spooled up, the Northstar set off and after a long run she lifted off just perfectly. With Phil Davis helping to adjust the trims, an understandably nervous John flew the model round several high circuits, then brought it lower to give everyone a better look. Phil took the controls for a few more circuits and a roll, and after 7 or 8 minutes everyone cheered a perfect touchdown back on Loch Tay. I reported this in a UK model magazine at the time and asked if anyone had flown a jet seaplane before. Nobody replied, so was this the world’s first model jet waterplane?



The engine was an Australian TJT 3000, rated at 32 lb thrust but trimmed back to give 26 lb, the model weighed 25 lb including 3 litres of fuel.

Vettster

Interesting story Alasdair.. Thanks for posting. i cant wait to do this...

alasdair

Here's my own latest development, finally finished and flying..

power is a Wren 44 gold rated at 10 pounds thrust.

rhklenke

My Feedback: (24)

Here's mine from Joe Nall in 2009. AMT Mercury Powered, 24 lbs wet...


Bob

Vettster

Very cool. P-60 I'm guessing? I'm installing my K-85 in the WestJet as we speak. Sadly I don't have a water base to fly from, so it will be maidened as a turbine from a sod field. Even with the underpowered prop setup, I found that it will move on grass if I wax the hull. I tried it on wet grass with no wax and the grass actual had a better grip than when dry. After waxing, it took off like the National lampoons family vacation when he was on the sled LOL

I'm doing the build on RCG as that site is much more user friendly.

Cutting pipe...
https://www.rcgroups.com/forums/show...Cutting-a-pipe

Installation...
https://www.rcgroups.com/forums/show...WetJet-upgrade

c/f

My Feedback: (1)

Ok ,

I have an AMT Mercury spare for $500.... and having built an flown many waterborne to flying airborne tunnel hulls, the water contact running surfaces should include aprox 1/8" extension beyond the skimming surface area on sides and in rear step. Water going around a smooth 90deg bottom to side creates suction to water. Some weird bernuiili effect for lack of technical term. My Winston Eagle Flying Tunnel hull actually sprays water in a picturesque rooster tail off the sponsons as I round buoys prior to lift off. Big difference with this feature.

This I learned from Ernest and Mike who created the first flying hydro foam tunnel hull craze back some years ago.

c/f

My Feedback: (1)

I like the idea of canards version, having learned on a Kangaroo, then Bobcat XL , Kingcat, Comp Bobcat, the turbine mounting position thrust angle becomes sensitive once raised above the wing centerline and is throttle dependent, causing an extreme push downward on nose. The canards could really dial that in with a gyro or free mixing easier and with much more authority than does the elevons..02

Vettster

Thanks for the your advise c/f.
During the build process, Laddie Mikulasko chimed in to offer his advise and that's what I went with.
Turbine powered WETJET

And here's the results.
Turbine powered WETJET

I may be adding a skirt as you described to the Step. It might have to go back another inch. I wont know till I find somewhere to fly. I just moved 6 months ago. One water based club gave me permission to fly it, however after seeing the site for the first time, I decided there's no way! Great location and clearance and all.. but the 15-20 tin can fishing boats on the water was not something I wanted to risk.

alasdair

My first jet was a Baby Boomerang, and my second a CARF New Rookie (many years ago when I had hair).
[img]"F:\Archive\My Pictures\MyModels\Rookie\me.jpg"[/img]
I thought the New Rookie might make a decent waterplane, but there were 2 problems. 1. All the servo linkages and access were on the underside and 2. It would not come down without airbrake, which was on the belly, underneath.
[img]"F:\Archive\My Pictures\MyModels\Rookie\brakes.jpg"[/img]
So after many years of design and building I came up wit "Morar", powered by a 10 lb thrust Wren 44
[img]"F:\Archive\My Pictures\Designs\Morar\IMG_20220423_142926_446.jpg "[/img]
OK guys! How do you put photos in posts? I have done it in the past, but I forget.