Soaking a propeller in water?

Call me a traditionalist but I fly principally with the wooden Tornado wooden props from my fabled "stash". The only time I resort to plastic props is when the plane that I am flying is one I've not flown before.

Gray Cox props by Cox are intended for competition purposes and are stiffer than the "rubber duckie" black plastic props which are intended for general flying. (They are also slightly less expensive.)

Plastic is an oil based product so I am not sure what soaking in water alone would do if anything.

Now soaking them in boiling water may loosen things up and re-align molecules perhaps. The new cox Rubber Duckies do work well and are plenty tough (I crash a lot too) although like Rusty I have been using cut down Master Airscrews.

Cut down 6x3 Black Cox props work well too.

Ron

Soaking plastic props in water has been discussed here before. What can it hurt?

The concensus was, if it makes you feel better do it and get back to us. No one ever did.

SuperDave wrote:Soaking plastic props in water has been discussed here before. What can it hurt?

Worst case... your eye, I suppose. I've thought about trying boiling an old Top Flite 5.25x4 for my Tee Dee, but couldn't convince myself to risk using it. Especially when I can buy a pair of new MA props for $2.00, even though they don't look as cool.

Back in the day, it was boiling nylon props. Supposed to 'toughen' them, although not sure exactly what that meant. Maybe when the DI (Jack Webb) was yelling at them, they wouldn't flinch...

I have never heard anyone soaking or boiling a plastic prop like a Cox rubber ducky in water.It's hard to see what good water would do to plastic in the first place since plastic is waterproof.
Years ago, an old time (older than me) control line guy told me that nylon props like Top Flight, for example, needed to be boiled in water for about 3 minutes every so often to replace the water molecules in the nylon that were lost from centrifugal force during running. Ditto if the prop had been left in a very hot area like your car dashboard. The boiling replaced the water quickly.
What I do is add a small amount of red Rit dye to the water before the boiling starts and the prop comes out a beautiful crimson color.The coloring not only looks good but now I know which props had been boiled already, and their visibilty while running is a major safety feature.Just boil for about 3 minutes take them out of the water and let them cool for a while and you are "good to go and ready to launch"
FWIW, Steve...........

ahrma_581 wrote:Back in the day, it was boiling nylon props. Supposed to 'toughen' them, although not sure exactly what that meant. Maybe when the DI (Jack Webb) was yelling at them, they wouldn't flinch...

cribbs74 wrote:Plastic is an oil based product so I am not sure what soaking in water alone would do if anything.

Ron --

Actually, nylon is quite hydroscopic and can absorb 6 to 9% by weight in water, depending on how dry it was to start. Here is an exerpt on nylon properties (not model related -- colors are my addition):

Nylon

Facts about Nylon

A large portion of our products are made from the thermoplastic Nylon. This material deserves a section on its own.

Nylon is used as a generic name for the Polyamide (PA) group of polymers. As a general family the PA group is low cost, rigid, translucent, has good temperature stability, abrasion and fatigue resistance.

Nylons and Moisture

All Nylons are considered hygroscopic. This means that they can absorb or release moisture based on environmental conditions. Nylon is more hygroscopic when compared to most other polymers.

Household example: Compare the relative wetness of fabrics when you move clothes from the washer to dryer. Nylon will be wettest of the synthetics, followed by polyester, then acrylic. Acrylic clothing will be almost completely dry after the spin cycle because it absorbs virtually no water.

Moisture acts as a plasticizer. A Plasticizer is something that increases flexibility, workability, or stretch ability. Dimensional and physical property changes take place during moisture absorption.

Moisture absorption and rate of absorption is dependant on the temperature, the relative humidity of the environment, and the wall thickness of the specific part.

Various nylons within the nylon family can absorb different amounts of moisture. The lower numbered nylons such as 4/6, 6, 6/6, absorb more than higher numbered ones such as 11, 12.

PA can be tough when the moisture content is right (2-3% @ 20°C) but dry products tend to become brittle. In general, moisture absorption may lead to an increase in toughness and reduction in stiffness and strength at room temperature. Or in other words, “dry” parts will have a higher tensile strength but will become less flexible, more brittle and less impact resistant. “Moist” parts will have a lower tensile strength but will be more flexible, less brittle and more impact resistant.

During the manufacturing process parts become completely dry. Right after molding they are in a state referred to as “Dry as Molded” (D.A.M.). For this reason nylon parts are often conditioned after processing to optimize the physical properties. Parts are shipped with the proper amount of moisture (liquid water) added in the sealed bags. Over time the moisture is absorbed into the dry as molded parts. Physical properties of parts can change in as little as 24 hours if left opened to the environment. Do not open bags until ready to use them. Seal bags when not needed.

66 Malibu wrote:Years ago, an old time (older than me) control line guy told me that nylon props like Top Flight, for example, needed to be boiled in water for about 3 minutes every so often to replace the water molecules in the nylon that were lost from centrifugal force during running. Ditto if the prop had been left in a very hot area like your car dashboard. The boiling replaced the water quickly.

ahrma_581 wrote:Back in the day, it was boiling nylon props. Supposed to 'toughen' them, although not sure exactly what that meant. Maybe when the DI (Jack Webb) was yelling at them, they wouldn't flinch...

It's true larger nylon props (8"+) had to be boiled and that they would get brittle in a short time, but I really don't think it had anything to do with water molecules in the nylon that were lost from centrifugal force and boiling didn't toughen them.

Top Flite used to pack a little note in each cardboard box of ten, telling the consumer to boil them before first use and to store them wrapped in a damp towel placed in a plastic bag. I remember using them on my Fox .35 as a kid, it was kind of cool watching that prop flex as the plane pulled vertical and broke into a two cycle. I think its probably fine to boil up some 1/2a nylon props for use, but I leave the old larger nylon ones alone.

I can see the expression my wife's face when I boil a sauce pan full of 1/2A props on the kitchen stove.

SuperDave wrote:I can see the expression my wife's face when I boil a sause pan full of 1/2A props on the kitchen stove.

She's still not used to your hobby related oddities?

True Rusty and we've been married fifty-one years.

She claims I've gotten weirder each one of them.

We compliment each other's neuroses though.

SuperDave wrote:I can see the expression my wife's face when I boil a sauce pan full of 1/2A props on the kitchen stove.

Last night my wife picked up a glass of props in water sitting on the counter, looked at it, then set it down and walked away...Her expression was priceless.

Phil

Phil:

You should have said that you were going to use the props as skewers for your Martini olives but they needed to be cleaned first. Nitro residue is a hazardous waste.

SuperDave wrote:Call me a traditionalist but I fly principally with the wooden Tornado wooden props from my fabled "stash".

Might those be Tornado "Plasticote" props? I still have a couple.

When Tornado first came out with their white nylon props they were supposed to be unbreakable...and they appeared so. Next batch were more brittle. That's when I remember the instructions for boiling them appeared.

Now, regarding nylon - do you suppose we should soak our Space Bug Junior tanks in water before putting them on a plane? I was about to build a plane for one.

George

In the olden days with Tornado nylons it was common practice to boil props in water. It made them less prone to breakage. Soaking in plain room temp water does nothing.

dankar04 wrote:In the olden days with Tornado nylons it was common practice to boil props in water. It made them less prone to breakage. Soaking in plain room temp water does nothing.

Interesting to know. I was under the impression that boiling just speeded up the process.

George

dankar04 wrote:In the olden days with Tornado nylons it was common practice to boil props in water. It made them less prone to breakage. Soaking in plain room temp water does nothing.

I am pretty sure that overnight soaking in room temperature made a difference on the old propeller that I soaked. The difference in flexibility was quite remarkable. That prop was in an attic for 20 years.

While it broke (before I soaked it), I only had the one half, the other half is lost in my lawn, and has been rained on so probably not valid for comparison even if I did find it.

Phil

gcb wrote:

dankar04 wrote:In the olden days with Tornado nylons it was common practice to boil props in water. It made them less prone to breakage. Soaking in plain room temp water does nothing.

Interesting to know. I was under the impression that boiling just speeded up the process.

George

Nylon will absorb water at room temperature. I agree with George that the boiling likely speeds up the process and may help relieve some of the molding stresses in the prop.

Bingo, thats why we did it to relive stress in prop. When we flew .35 combat ships in the day a wood prop was a one shot deal. You get points for airtime, beside a possible kill of streamer. It worked and props would take quite a beating.

Boiling nylon items (not just props) is fun. What makes it fun is adding some RIT dye to the water - if the props start out white, you can dye them any color you want. I've even tie-dyed props (boil them in plain water first, then wrap masking tape in a spiral around them and re-boil in dye). I boil my bellcranks and control horns, as well as my old nylon props before use (years ago I bought horns and bellcranks from SIG in bulk, dyed them various colors and sold them on ebay).

Iskandar

iskandar taib wrote:...I boil my bellcranks and control horns, as well as my old nylon props before use (years ago I bought horns and bellcranks from SIG in bulk, dyed them various colors and sold them on ebay).

Iskandar

GOOD IDEA! Never thought of that. I have some of those old parts too.

Thanks Isky!

George