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[Capricorn]

John, 

Thanks for the added info.  30k rpm is a lot, but you know I had an old dremel that was constant speed at 30k rpm and it had a brushed motor, and none of it ever wore out on me.  I actually ended up frying it using it as a circuit tester of all the stupid things, lucky I didn't electrocute myself.  We have 120 AC here typically, but for some circuits there is 240, like a well pump.  I found some old wires sticking out of the wall in the garage and decide to make an outlet not knowing it was a 240 hook up, poof end of said dremmel.

So what's the best lightweight rotor material?  How big of a difference do you think it makes?  Is it just the time it takes to reverse direction and accelerate?  I may be better off if mine doesn't accelerate too fast per what Andrew said in earlier post, 4 seconds is close to my reaction time so it might suit.

Andrew, I have since smoothed over the mounting blocks so they aren't dead square, I may try to turn a cone to fit on the end of each block, I wish I had chunks of brass around like John, I may able to find something suitable at the hardware store to modify.  I did plan on glassing it without anything but the blocks on, even that I almost wished I'd left off but I think I had to.

I still hesitate to go forth with the glassing, but probably a good thing, usually I dive in without preparation, maybe I'm getting a bit smarter in that respect.  One question; say it starts out horrible, I mix the epoxy wrong or something, can you pull the cloth off and wash the epoxy off with something if needed?  It always makes me feel better if I know there is an escape.

Cap

[andrewh]

Cap,

Worry not, there are fixes for almost any of the possible errors known to mankind.

But preparation and planning  - working the entire job through in your head, and having all the materials prepared is the key.
Work in small batches of resin - you don't have to do it in one mix
Cheat like mad (did I mention giving the cloth - the side next to the hull the lightest possible spray of spraymount so it doesnt want to squirm.
Warm the resin and hardener to very warm room temperature before you begin
start on detachable bits - convince yourself that the epoxy resin does cure reliably

You can't mix the epoxy wrong - well, you CAN, but you are the person who made that airship frame, and the Fletch hull in the first place - you won't
Each batch needs to mix for 2 minutes -
Be bloody bold and resolute.
andrew
 

[bogstandard]

Cap,
The lightweight rotor is just not for runup and change over times, it is for stopping as well. The faster you can stop, the safer you are.
I have some lumps of titanium, but I think the machining would cost a fortune in blunted tooling. So I might just look at aluminium bronze or a thinner skimmed brass rotor. I think I could get a brass one down to about half the weight of the original, maybe even more, because of only using two drive areas instead of three.

John

[Capricorn]

Andrew,

It was not worked out well in my head, and what I thought would happen with the rudder happened, but maybe I was mistaken initially.  I mixed the epoxy just fine (2 minutes, lot's of bubbles but they went away), spread it on and put on the cloth, perfect so far.  The problem was the three edges, I had thought I was supposed to fold the cloth over and overlap it, I didn't think that would work and it didn't, it frayed and wouldn't stay down, so I left them as flaps all the way around.  Maybe that's the way it's supposed to be done, I hope, because that's the way it is.  If I have to I'll carve another rudder.

Maybe it's not the right cloth, it frays easily, it's pretty fine almost like Oxford cloth.  I could see doing the hull with it easy enough if it weren't for the blocks sticking up, also around the fantail I think it might bunch up, what do you do then?  I sure wouldn't want to cut a slit and over lap it but at least it's lapped on a relatively flat surface rather than a 180 corner.  And of course the bow is going to have to be slit so I'm not too excited about it.

We'll see tomorrow what it ends up like.

John, I see how the lighter rotor would be better as long as it's strong enough which I'm sure you'll acheive.  Too bad the titanium is so tough to machine, it's probably expensive to.  I know those milling cutters are expensive, even the cheap ones. 

[Capricorn]

Well the rudder turned out fine.  The edges sanded right off and no frayed cloth sticking out anywhere.  I'm glad I practiced on the rudder and got over it.  Cap

[Capricorn]

Hull is getting closer, it's fiberglassed, needs a bit of work yet but looks like it will be fine (to me).

Poor picture but, it's better than it looks:

[Capricorn]

A few more pictures, slow but sure progress.  Will hopefully have in water by end of summer , I had hoped to by now but at current rate it's going to be a bit longer.  Maybe within a month.  Hope to test motors that I have with 75mm props, may need bigger motors and bigger props, we'll see.

[Capricorn]

Hello all,

Ready for first test run, wish me luck.

Cap

[Martin (Admin)]

Didn't realize the thing was THAT big! 

[Capricorn]

Hi Martin, it's actually too big, I'm going to need another boat to follow around, get away from shore.  It's got a lot of room though.  First voyage with electric motors went ok, just chose a poor location, not much room and too may hazards, I wasn't able to get it up to full speed but close I guess.  Cap