Test005

1. Can a standard Hobbico tachometer reliably be used on a 3-blade black prop such as the Master Air Screw. (If a tach is adjusted to count every blade passing, perhaps I need to deduct xx% of the tach reding to compensate for the extra blade? )

2. If I sidemount a heavy engine (cylinder pointing right, exhaust pointing down), do I need to take extra care on the lateral balance, or will the propeller momentum compensate the extra weight of the engine cylinder.

3. Will Acrylatic spray paint, used for RC-car lexan bodies be fuelproof and OK to use on a ABS plastic plane that runs 15% nitro.

DBCherry

My Feedback: (4)

Most Tachs have settings for 2, 3 and 4 bladed props.

An engine mounted at 90 degrees (horizontally) will put slightly more weight to one side, but it may not be significant. Just hold it by the spinner or prop shaft and under the vertical stab, and add weight if you think it's off balanced enough to be worthwhile.

I doubt that the Acrylic paint you mention is fuelproof, but try a bit on some plastic, let it dry for 24 to 48 hours and then try it. You can always fuel proof it later with something like Lustrecote clear.
Dennis-

Test005

Thanks for the input:
I've used this Acrylic paint to paint a lexan buggy body and it seemed fuelproof.
My question was a bit more if somebody had tried it on ABS plastic, perhaps it doesn't work the same as on lexan.

In Finland we just don't have too many model flyers so the local hobby businesses are rather small.
I get some stuff from the local hobby shop which has a limited selection, I get some stuff online and other stuff you have to fabricate yourself and/or buy from non-hobby-specific places such as automotive shops, bookstore, hardware store etc...
we don't have any huge modelshops with isle after isle full of hobby-specific goods, and lustrecoat is nowhere to be found

Campy

My Feedback: (1)

As for the paint, I use latex (either flat or semi-gloss ) to paint my planes and then clear coat them with 2 coats of a waterbase polyurethane to make them fuel resistant. I use different "glosses" of polyurethane to obtain the degree of "shine" I want - i.e. satin for most warbirds, etc.

The latex will take about 7 - 10 days to "cure" (completely dry ), and should be allowed to cure before clear coating. The waterbase polyurethane is fuel resistant to 10% nitro (maybe more ) and the waterbase poly will not yellow over time as the oil base polyurethane does.

Dukester

My Feedback: (31)

On the tach question, if your tach is only set up for 2 blades, then its pretty simple to convert the result. On your tach, if one rpm is equal to 2 blade passages, then 3 rotations would be 6 blade passages. Since you have a 3 blade prop, then 6 blade passages would only be 2 rotations, so to get a true rpm for a 3 blade prop, you just take 2/3 of the 2 blade reading on the tach.

Make sense?
Duke

Broken

Dukeser is right- Just have a calculator handy and do this:

Lets say your 2 blade rpm reading on your three blade prop is 24000 RPM ((Zoom))

24000 X 0.66 =15840 Your three blade RPM is 15840

(2 blade reading) X .66 = Three blade
(2 blade reading) X .50 = Four blade
(2 blade reading) X .20 = Five blade -fun ehhh...

CafeenMan

I think I'd just tell everyone that my engine turns 24K.

Test005

Thans guys, that's what I had in mind.
I'll do the initial break in with a normal two-bladed prop though to keep in simple and then I put the three blade for more scale appearance.

Test005

The paint I mentioned in my original post is called: "Pactra Racing Finish" and is for painting lexan car bodies.

I've done some searches with Google and it seem like I can use this paint on my plastic plane.
The Car race guys use it so it must be fuel proof.