What is detounging and how do you balance props?

[Darin Jordan]

Nevertheless, there must be some general rules. For example what do you do to reduce lift? How can you increase lift? How can you concntrate the thrust cone and when should you want to do that? Etc.

-t

Did you read the Link I posted???

[tharmer]

again and again, Darrin. Really good info there, but there is so much more. Admittedly, much is trial and error, but it would be nice to have as much practical data as possible.

For example, it might be obvious that you never combine a back cut with a barr cut (I don't know that this is true), but I could ruin a few props finding out when the data is already out there.

There is good info on aspect ratios in your link. I hadn't thought much about that. The relationship between pitch and lift isn't talked about much. If you have more pitch, should you also consider trimming the TE? Don't know.

No one has to re-invent anything here...it would just be nice if all the currently "google-able" info about prop work were in one place.

-t

BTW are you going to be at Twin Lakes?

[Darin Jordan]

I've never found a single source of info better than the one I posted. It gives you all the basics on what adjustments do what...

If you want less lift, you can add cup at D, back-cut, or barr-cut... If you need to unload the motor more, then you can back-cut, or barr-cut... If you need more pitch, then you bend along lines C, B, and A... If you need more RPMS and lower end performance isn't as important, you detounge...

Lift is created by water shedding straight off the ends of the blades... when you back-cut, or add cup to the prop, you redirect the thrust cone backwards, reducing lift and increasing thrust... etc...

All of these can, and should be used, in combinations. But I don't think too many people can say here, do "X", "Y", and "Z", and you'll have what you need... We all start with the basics... I ALWAYS detounge my props... but then, I know I want that done...

I found this word document, however, that gives a good description on how to generally prepare a metal prop, which should prove helpful for first-timers to get started.

[785boats]

Here's some interesting reading from Model Power Boats.com, thanks to Andy Kunz, Mike T. & Carlos Andrade.

http://www.modelpowerboat.com/forum/article/propellers.htm

http://www.modelpowerboat.com/forum/article/improving-your-prop.htm

http://www.modelpowerboat.com/forum/article/propeller-balancing.htm

Have fun.
Paul.

[Stinger9D9]

I know this may sound like a broken record, but I work with hazardous materials all the time...particularly asbestos, so when I hear the warnings about beryllium dust, I pay attention.

This is directly from the bottom of the prop balancing article:

Caution when working with Beryllium Cooper! Activities such as grinding, sanding, polishing or any activity which abrades the surface will cause airborne dust particles. These Beryllium Cooper particles are highly toxic! There are dangers involved with inhaling dust or fumes. It can cause serious, chronic lung disease in some individuals. Over time lung disease can be fatal! Warning- Potential Cancer hazard!

That warning sounds suspiciously like the warning for asbestos. If you say the "a" word people generally go running in the other direction, but for some reason, since it's "just a little" bit of filing or sanding on a boat propeller, people don't seem nearly as concerned.

Remember, some of these respiratory diseases have a long (20 year) latency period, so you may not immediately notice any ill effects - in yourself, or in members of your household that may become exposed.

Now because of my line of work, I have access to respirators and protective equipment and have been trained on how to use them. Unfortunately, most people don't have access to, or training with respirators.

So keep this in mind when working with these propellers. Remember, it's not the dust you can see...it is the airborne dust particles that are too small to see that are the real concern.

[Blackjack-sven]

Now because of my line of work, I have access to respirators and protective equipment and have been trained on how to use them. Unfortunately, most people don't have access to, or training with respirators.

This is very good info, and seeing as you do this type of work you should sell this product to the rc world with the training, as lots of people think it's ok to work with the "Stifzel" product from team losi without using protection like a respirator. I worked in the army for 12 years and also have the experience with respirators and also use one myself when working with almost any material that will produce dust or fumes.