Argess

After writing a post about my unfinished SK Daddle 40 I stumbled across my old Drag'N Fly 20 MK2 and thought I’d post some pics.

It’s not the best, but it was a very long time ago when I built it. In fact, back about 1983. Only boat I had built previous to this was an 049 Dumas Lil Swamp Buggy, which I eventually fitted with an OS Pixie single channel RC system. I still have it. But I digress...

What I actually wanted was this:



But the Hobby Shop brought in this instead:



So I bought it anyway. I bought the cheapest radio I could find, which was a Cox/Sanwa 2-ch system intended for aircraft. The kit could be used with an outboard or inboard. Since I chose the inboard, I built the cowl with the angle reversed so it sloped down towards the stern.



I used an OS 20 Marine, made my own flywheel, u-joint, engine mounting plate and prop tube and shaft.



I had a lot of cavitation, so I made up a tab to help, but havn’t actually tried it since. It’s not easy to start as there isn’t room for a starting o-ring, so I use a rubberized string. Every attempt means letting go of the string. Tedious. A smaller flywheel should fix that problem. No doubt the one I made is larger than necessary.



The poor boat needs a little TLC. As a minimum, sanding and paint could do wonders. At least a refurbishment is now on my "list", so it will eventually get done.

c.k.y.

[quote]ORIGINAL: Argess

After writing a post about my unfinished SK Daddle 40 I stumbled across my old Drag'N Fly 20 MK2 and thought I’d post some pics.

It’s not the best, but it was a very long time ago when I built it. In fact, back about 1983. Only boat I had built previous to this was an 049 Dumas Lil Swamp Buggy, which I eventually fitted with an OS Pixie single channel RC system. I still have it. But I digress...

What I actually wanted was this:


Hi Argess
Good memories !
Difficult to get saved so good
Copper flywheel is right it can make the machine run more stable !!
I think the owner was a person over the age of 50.
CKY

coriolan

The prop you have on it looks like a Graupner which isn't the best for IC use, most time cavitation indicate too small a diameter or pitch(specially if the hull is heavy,like most Dumas kits). The OS 20 being a baffled piston design isn't a power house but still should move that hull; One way to deal with cavitation is a vigorous launch so the prop get a better chance to grab water instead of sucking air!

Argess

You have a good eye, but the flywheel is actually bearing bronze (sintered bronze). It's all I could find at the time and I was worried it might explode at high rpms. But I bench tested it and it held up fine. Interesting material to machine. Instead of the lathe bit producing shavings, the metal came off like heavy powder.

And "yes"... good memories and I am over 50! LOL.

I have no doubt you are correct. The cavitation would occur when I tried to apply throttle and no matter how softly I eased into it, no go. I had to give a push to get it moving. Once up on a plane, it scooted along very quickly. I was actually surprised at it's speed, although no doubt it's very slow by today's standards. I should investigate an alternate propellor, although my LHS doesn't have much of a selection. They cater to aircraft mostly, and ground vehicles second.

coriolan

As my repply in your other SK-Daddle 40 thread you can find most Octura props and hardware at Gravesrc:
http://www.gravesrc.com/category_s/421.htm
Octura never had a website and can only be reached by phone or fax (pity!), it has become difficult to buy boat stuff in the last 10 years or so but its worth the effort to find a good source! I admire your decision to make a flywheel out of sintered bronze, not easy to machine and very expensive these days, steel or brass would have been enough weight for the purpose
Ma first boat with a "real modern engine" was a Dumas Pay'n'pack with a marine K&B 3.5(no pipe, just exhaust throttle+muffler), I had used plastic props before with baffled engines without problem and tried an Octura 1440 (plastic) as I didn't knew what size would be appropriate for that engine. The prop lost its two blades as soon as the boat touched the water
Here is their address,fax and phone:
http://skokiechamber.chambermaster.c...qualifier=info
You can fax them with your computer and they will send you a current price list.