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View Full Version : Resurrecting my RC model Donzi project



DickB
11-22-2010, 09:03 PM
I posted quite a while back when I started building a 1/4 scale Donzi Classic model, but then I got sidetracked by other things. This winter I am dusting off the project and getting back to it. Since it has been so long ago, I thought a new thread was appropriate.

The model will be radio controlled, powered by a gasoline weed-eater type motor, but one specifically made for model boats.

The hull construction pictures were all taken during the first phase of construction. Construction is marine plywood frames and skin with West epoxy glue and waterproofing. The exterior hull and deck are covered in fiberglass and epoxy. Strakes are maple.

I was going to use a relatively uncommon model outdrive, but today there is really only one source, in Germany, it is expensive, and it is not the correct scale or type for my model.

A more common drive assembly for gas models of this type consists of a fixed strut with an integrated prop drive shaft running parallel to the waterline. A flexible cable runs from the motor to the front of this shaft through a stuffing tube. For performance the setup is almost always surface drive. A separate rudder or rudders is used. A variation is to use a steerable strut and no rudder. I plan to essentially make a steerable strut that looks like a Mercuiser Alpha outdrive. I have a CNC router and have been designing the outdrive parts. It will be built up out of four maple parts with metal skeg, prop shaft tube, and steering tube. I may cut a draft set of parts tomorrow to check fit.

yeller
11-22-2010, 10:07 PM
Wow! Looks great.

I'm guessing the flexible shaft is similar to the cable used in speedometer cables?

ITTLFLI
11-23-2010, 07:08 AM
Very cool!!:shades:

Rob M
11-23-2010, 07:23 AM
That looks awesome so far! Great project.

glashole
11-23-2010, 09:57 AM
can an alpha drive take the weedeater power?

should have gone with a bravo x

Conquistador_del_mar
11-23-2010, 11:05 AM
Hi Dick,
Highly cool project which you always seem to accomplish. Do you think there will be enough distance between the strut and steerable outdrive to be able to flex the cable enough for adaquate steering? My rigs use separate rudders with the cooling tube pickups integrated into the rudder or they are steerable outboards. I look forward to seeing the progress. Bill

DickB
11-23-2010, 08:56 PM
Yeller, yes, only a little beefier at 1/4" diameter. Actually used in weedeaters also.

Conquistador, I posted this concept on the RCUniverse forum and got a few replies saying it should work. In fact, a link to a similar commercial product was posted:
http://www.wd200-modellbau.de/?Antriebe%2FDrives:Z-Drive%2FDirektantrieb

thatgirl
11-24-2010, 06:27 AM
Hi Dick,
Highly cool project which you always seem to accomplish. Do you think there will be enough distance between the strut and steerable outdrive to be able to flex the cable enough for adaquate steering? My rigs use separate rudders with the cooling tube pickups integrated into the rudder or they are steerable outboards. I look forward to seeing the progress. Bill
that is so cool will you be selling them? if so count me in .keep us posted on progress

Sweet Cheekz
11-24-2010, 07:28 AM
Dick
What you can get accomplished with wood makes me so jealous. Cant wait to see this progress. Hope you bring it to AOTH alog with that beautiful boat of yours

Parnell

DickB
11-29-2010, 02:44 PM
I ran a test carve in pine and I have a few things to tweak, but it's looking pretty good so far. I will probably try fabricating a gimbal ring out of aluminum.

DickB
11-29-2010, 02:48 PM
that is so cool will you be selling them? if so count me in .keep us posted on progress
Not sure about selling them. Someone on the RC Universe forum contacted me. He makes castings of hatches, scoops, deck hardware, etc. and would like me to send him a finished drive so he can make a mold and cast it. That might be the way to go.

A nice part about this is that I can easily scale these up or down. I'm building 1/4 scale which is pretty big; 1/8 scale is more common I think. What size are you looking for?

DickB
11-30-2010, 06:41 PM
Ran the final in maple today. I'm pretty happy with the way it turned out so far. The two halves are temporarily bolted together for initial sanding. I plan to use aluminum for the cavitation plate. The hydraulic rams won't be power operated, but will probably contain a screw mechanism for adjusting the trim. Gimbal ring is next.

McGary911
11-30-2010, 08:31 PM
Very nice work all around. Outdrive looks great. Guess you'll be giving up a little speed for a more accurate look, huh? If all you wanted was speed, you'd do some lightweight fiberglass thing.

Really anxious to see how this thing ultimately turns out. Looks like magazine material so far.....

Just Say N20
12-01-2010, 08:22 AM
What Parnell said.

Spectacular!

DonziJon
12-01-2010, 09:15 AM
Ran the final in maple today. I'm pretty happy with the way it turned out so far. The two halves are temporarily bolted together for initial sanding. I plan to use aluminum for the cavitation plate. The hydraulic rams won't be power operated, but will probably contain a screw mechanism for adjusting the trim. Gimbal ring is next.

Nice job Dick. I can only assume you have a modelers CNC Milling Machine to do such acurate work on that drive.

I have a SHERLINE Modelers Lathe that is CNC capable but I havn't added the CNC attachments. Laminating the drive is a good idea because I would think otherwise the wood would warp after being in the water, particularly a hardwood, regardless of how it was sealed. :wink: DJ

CHACHI
12-01-2010, 10:45 AM
Hey DonziJon, why don't you start a thread to shoecase your handiwork with wood.

I am sure their are people here who "wood" enjoy it, after all they are just small boats.:wink:

Ken

Tom Smith
12-04-2010, 09:10 AM
Very interesting. I have been RC model building, mostly airplanes, for 50 years. Can't wait to see more of this beauty. Tom

THEDONZ33
12-08-2010, 02:17 PM
Any Offshore style RC hobbiest needs to check out the :
www.bonzisports.com
Website