Previous in Forum: Anes E-Z Power Converter   Next in Forum: Input Range Calculations
Close
Close
Close
15 comments
Participant

Join Date: Jun 2011
Posts: 3

Making a Propeller

06/07/2011 3:28 AM

I'm making RC helicopter and I need to make my own propellers. I know that one end of the propeller should be in angle of 90 degrees compared with the other end. But can anyone give me more information on how to build/make it?

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
2
Guru
Hobbies - Fishing - Old Salt Hobbies - CNC - New Member United States - US - Statue of Liberty - New Member

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5198
Good Answers: 266
#1

Re: Making a propeller

06/07/2011 6:55 AM
__________________
Life is not a journey to the grave with the intention of arriving in a pretty, pristine body but rather to come sliding in sideways, all used up and exclaiming, "Wow, what a ride!"
Register to Reply Good Answer (Score 2)
Participant

Join Date: Jun 2011
Posts: 3
#2
In reply to #1

Re: Making a propeller

06/07/2011 12:55 PM

Thank you. The link you gave me is for making airfoils, which means it can be used for making airplanes, it can't help me with my propeller problem.

Register to Reply
Guru
Hobbies - DIY Welding - Don't Know What Made The Old Title Attractive... Popular Science - Weaponology - New Member United States - US - Statue of Liberty - 60 Year Member

Join Date: Apr 2009
Location: Yellowstone Valley, in Big Sky Country
Posts: 6954
Good Answers: 282
#3
In reply to #2

Re: Making a propeller

06/07/2011 1:43 PM

What is a "Propeller", other than an airfoil?

I suspect that a search of "Helicopter Rotor" will yield more information than "Propeller". The link to a Wikipedia article will should point you in the right direction.

[edit] I posted before looking at the link provided by ozzb. That is a pretty good explanation of basic rotor balde geometry... why the resistance to it? Or, are we answering the wrong question?

GA for ozzb.

__________________
When you come to a fork in the road, take it. (Yogiism)
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#8
In reply to #2

Re: Making a propeller

06/08/2011 7:33 AM

You appear to have a lot of misconceptions, but maybe English is not your first language? Which would explain a lot.

The link that someone sent you (http://www.cybercom.net/~copters/aero/airfoils.html) was for the airfoil section of a Helicopter blade. As the first line(s) of the link said, the reason that a Helicopter flies is the same reason that an aircraft flies......

Also, not that I am an expert, but I have never seen a Helicopter blade with a 90° twist in it that you mentioned.........

Most model makers actually go and buy the components from a model shop and build the complete setup, as making it themselves is a ridiculous amount of work for any sane person. Plus it probably works out even more expense in DIY mode....

Best wishes.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Participant

Join Date: Jun 2011
Posts: 3
#10
In reply to #8

Re: Making a propeller

06/08/2011 8:19 AM

You are right, English is not my first language :)

I should search for helicopter blades, instead of "propellers", so I apologize for the whole mess.

I can't buy the components from a model shop, because model shops simply don't exist in our country(Macedonia), so I should travel to Greece, or Bulgaria maybe which would cost me more than trying to make my own.

Thank you very much, it seems that link that I've got for the airfoils is the thing I've been looking for.

Register to Reply
Guru
Hobbies - Fishing - Old Salt Hobbies - CNC - New Member United States - US - Statue of Liberty - New Member

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5198
Good Answers: 266
#12
In reply to #10

Re: Making a propeller

06/08/2011 11:44 AM

UPS delivers there I would think that's cheaper then the travel cost.

__________________
Life is not a journey to the grave with the intention of arriving in a pretty, pristine body but rather to come sliding in sideways, all used up and exclaiming, "Wow, what a ride!"
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#13
In reply to #10

Re: Making a propeller

06/08/2011 1:46 PM

Have you never heard of catalogs? Order the parts and get them delivered by mail or one of those delivery companies.

In my model making youth, my nose was always in a catalog, planning what to buy next......when I had the money.......

Do please remember that rotors can be very dangerous if something breaks at high revolutions......you could be cut to ribbons, even killed, or other people just standing around.......

Don't DIY it!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Hobbies - Fishing - Old Salt Hobbies - CNC - New Member United States - US - Statue of Liberty - New Member

Join Date: Mar 2007
Location: Rosedale, Maryland USA
Posts: 5198
Good Answers: 266
#14
In reply to #8

Re: Making a propeller

06/09/2011 10:36 AM

I believe the twist he is talking about is because it's a model. A modern full scale helicopter has linkage that controls pitch of the blades to increase lift. On most models the only control is rpm. So they are made with a fixed pitch.

__________________
Life is not a journey to the grave with the intention of arriving in a pretty, pristine body but rather to come sliding in sideways, all used up and exclaiming, "Wow, what a ride!"
Register to Reply
Guru
Engineering Fields - Electromechanical Engineering - Technical Services Manager Canada - Member - Army brat Popular Science - Cosmology - What is Time and what is Energy? Technical Fields - Architecture - Draftsperson Hobbies - RC Aircraft - New Member

Join Date: Sep 2006
Location: Clive, Alberta, Canada
Posts: 5898
Good Answers: 204
#4

Re: Making a Propeller

06/07/2011 11:37 PM

there are significant differences between a aircraft Propeller and a Helicopter "Rotor", based on their intended functions. Rotor blades are simple naca type airfoils, that are essentially the same profile from root to tip. (the blades are also articulated, and the rotor is acting as an inverse cone)

here is a downloadable pdf, if the math interests you.

Register to Reply
3
Guru
Engineering Fields - Aerospace Engineering - Member United States - Member - Army Vet in the aviation industry

Join Date: Mar 2008
Location: Bridgewater, Va.
Posts: 2027
Good Answers: 112
#5

Re: Making a Propeller

06/07/2011 11:46 PM

First off, they aren't propellers. They are rotors, and rotors have multiple (rotor) blades.

From there, there are an infinite number of blade configurations and contours, including a varying number of blades on a rotor and whether the blades are symmetrical or asymmetrical. Also, tail rotors are of a typically significantly different design from main rotors

I would suggest you start doing a lot of research on an appropriate blade(s) for your particular helicopter.

BTW, I've never seen any blade that has a twist of 90 degrees and I've been around helicopters and airplanes for almost 50 years.

Hooker

Register to Reply Good Answer (Score 3)
Guru
Engineering Fields - Electromechanical Engineering - Technical Services Manager Canada - Member - Army brat Popular Science - Cosmology - What is Time and what is Energy? Technical Fields - Architecture - Draftsperson Hobbies - RC Aircraft - New Member

Join Date: Sep 2006
Location: Clive, Alberta, Canada
Posts: 5898
Good Answers: 204
#6
In reply to #5

Re: Making a Propeller

06/07/2011 11:58 PM

hey you,

that sounds oddly like plagiarism...

just because you are a helicopter pilot... and I have only flown on the computer... doesn't make it fair. I was here with the 'rotor' answer almost 7 minutes ahead of you.

chris

Register to Reply
Guru
Engineering Fields - Aerospace Engineering - Member United States - Member - Army Vet in the aviation industry

Join Date: Mar 2008
Location: Bridgewater, Va.
Posts: 2027
Good Answers: 112
#9
In reply to #6

Re: Making a Propeller

06/08/2011 8:10 AM

Arrrrggghhh...

It's the old internet inverse time zone effect that was instituted when the plagiarism thread was created. You got time stamped 9 minutes ahead of me though I'm 2 time zones ahead of you.

Or maybe because I had just taken off my aluminum foil hat for a few minutes while preparing for bed...

"They" got us, Chris.

'sides, I'm a starched wing pilot and a helicopter flight engineer. So there!

Hooker

Register to Reply
Power-User

Join Date: Jun 2009
Location: Australia
Posts: 277
Good Answers: 45
#7

Re: Making a Propeller

06/08/2011 2:08 AM

A propeller is basically a rotating aerofoil - so anything about aerofoils is relevant to each section through a propeller at a given radius from its centre of rotation - though you obviously also need some additional geometry rules.

Propellers are specified by pitch and diameter. Diameter is obvious enough and one method of defining pitch is the distance the propeller would screw through the air in one turn if there was no slippage in the air. Think of it like the pitch on a screw thread.

One point that derives from the above is that while the pitch or slope at the ends of a (2 bladed) propeller will always be opposite, it is not always the case that they will be at 90 degrees to each other.

A fine pitch propeller has the tips of its blades closer to parallel with each other (i.e. bite less air) and would be used for a high rev, low velocity, high thrust task, while a course pitch propeller would be the reverse of this. Variable pitch propellers, as used in practice, start at a fine setting for take-off and move to a course setting for high speed flight.

Now to actually set out one blade of a propeller:

1. Draw a horizontal line "x" inches long (call it the "radial" line), and then

2. Draw a vertical line upwards from the left hand end of the horizontal line you just drew, also about "x" long (call it the "axial" line). The actual length of the axial line is what determines the overall pitch of the propeller. See the next point.

3. Now if you draw a series of lines from the top the "axial line" to a number of equally points along the "radial" line (these are usually equi-spaced and are called stations), each of the resultant sloping lines will be the axis for the aerofoil section of the propeller at that position or station on the radial line.

You will see that the further away each point is from the "axial" line, or in other words from the centre of rotation of the propeller, the less the slope of the aerofoil section is - but each section would theoretically screw through the air the same distance for one turn of the propeller.

The tip speed of some propellers can be near the speed of sound though of course the speed near the centre of rotation will be much less. The rule for aerofoil section efficiency is that higher speeds need thinner sections - and so as you might expect, a good propeller will have fatter aerofoil sections nearer the centre of rotation for this reason. But there is a second reason and that is that additional material at the root of the blade gives added strength where it is needed.

The above is repeated as required for additional blades.

Register to Reply Score 1 for Good Answer
Guru
Engineering Fields - Construction Engineering - New Member Engineering Fields - Civil Engineering - New Member Hobbies - Fishing - New Member Hobbies - Target Shooting - New Member Hobbies - Hunting - New Member Popular Science - Weaponology - New Member United States - Member - New Member Hobbies - DIY Welding - New Member

Join Date: Apr 2007
Location: Latitude 38.701979 Longitude -90.439540 Coordinates 38.701979, -90.439540 N38°42.11874, W090°26.3724
Posts: 669
Good Answers: 15
#11

Re: Making a Propeller

06/08/2011 8:42 AM

I'm assuming you just prefer to make your own stuff but why are you making your own rotors for a RC helicopter. They are readily available in many sizes and materials. Most of the ones I see are fiberglass, carbon fiber or a few wood ones. Considering the damage I've seen when one comes apart when the RC pilot makes an error in their set up. I'd be very careful the first time you fire up your Helicopter. using your hand made rotors.

I have a friend that flies RC Helicopters. So if you need links to a supplier I can talk to him & find out where he buys his.

__________________
scotchdrnkr
Register to Reply
Guru
United States - Member - Hobbies - Fishing - New Member Hobbies - Target Shooting - New Member Hobbies - RC Aircraft - New Member Engineering Fields - Aerospace Engineering - New Member

Join Date: May 2009
Location: Saint Helens, Oregon
Posts: 2215
Good Answers: 69
#15

Re: Making a Propeller

06/09/2011 2:00 PM

I know, I weighing in late, but no one mentioned anything about a "Gyrocopter", which uses a "propeller" in it's configuration

__________________
Confucius once said, “ Ability will never catch up with the demand for it".
Register to Reply
Register to Reply 15 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

Andy Germany (2); chrisg288 (2); dj95401 (1); Doorman (1); Hooker (2); ozzb (3); scotchdrnkr (1); TrevorM (1); Vasileski (2)

Previous in Forum: Anes E-Z Power Converter   Next in Forum: Input Range Calculations

Advertisement