CGRetired

My Feedback: (1)

I am going to try to post the Prop Chart as a Sticky as requested by a couple of members. This prop chart is for glow powered planes. I will update it with one for electric as soon as I get it.

Also, based on a request from several RCU members, I'm going to add the basic electric setup guidelines to this sticky.

CGRetired
Moderator

goirish

Hey CG, I use that chart often. BTW how are you feeling?

CGRetired

My Feedback: (1)

Hi Irish

Great. It's nice to de-pressurize, ya know? I'm down in FL for a week, return tomorrow to the NJ weather.. blah. It's been nice here on the Gulf Coast.. temps in this low 80's.

The health issue is under close watch, going back to the Dr on Thursday for a follow-up. What's odd is that there were no indications other than discomfort. Tests proved negative. But, after the procedure two weeks ago, well, I'm feeling much better.

Thanks for asking, my friend!!

Dick.

CGRetired

My Feedback: (1)

Ok, folks.. I am going to do some "improvements" in this sticky from time to time. One thing I am going to do is add something for electric props too because that seems to come up as much as it does for Glow props.

Look for that in the near future.

By the way, please thank Gray Beard for the suggestion that this be a sticky. I am sure many will appreciate the effort and the knowledge he puts in this forum.
Thanks, Gene!!

And, of course, thanks OzMo for posting the chart in the first place. Guys like you keep things going on RCU.


CGRetired.

goirish

I would like to see a chart for electric. boy!! am I dumb when it comes to elect. I spent most of the day today trying to figure out where the fuel line went, never did find that sucker. Ordered a pair of Zurich sunglasses today. Original design, medium rose. 48.00 to my door. Model aviation has a zurich ad for 20 yankee green backs off.

CGRetired

My Feedback: (1)

Neat stuff! Those Zurich's are great.. and twenty times as great with twenty yankee greenbacks off!!

And, for those of you that follow Daylight Savings Time (some areas do not), don't forget.. SPRING FORWARD this weekend.. Set the clocks ahead one hour at 0200 Sunday morning. I'm going to get up at 0200 just to do that. Or, should I get up at 0100 because when I spring it forward, it will be 0200? This is confusing... [X(]

As far as that fuel line is concerned, Irish, this picture is just for you...

CGr

armody

My Feedback: (10)

CG,

Is it any reliable?

http://www.coastalplanes.com/tools/propchart.htm

CGRetired

My Feedback: (1)

How does it compare to the first chart?

CGr

armody

My Feedback: (10)

I did not mean to compare it, I wanted your opinion as you have more experience, that how much one can rely on it. I feel that the chart link I posted is pretty reliable, things at RC are mostly on approximation, ain't they?

CGRetired

My Feedback: (1)

They are always an approximation. They give you a starting point. So, you can pick one in the recommended size and fly with it. If it doesn't do what you want, you can up-range or down-range to something different until you find one that works.

CGr.

oskartek

CGRetired,

Here's a site that has helped me with electric props and motor combinations.
It doesn't cover every motor but it seems to work fairly well. It is by Markus Muller.


http://www.s4a.ch/eflight/motorcalc_e.htm


I hope this helps. Happy flying, Oscar

CGRetired

My Feedback: (1)

This is a cut and paste from a previous post in this forum:

Read through the following and work it out.

Once done, you will know what wattage you are working with and what motor and esc to buy. Always go to the higher level when figuring out what motor and esc to buy.. if it works out to 17 amp ESC, go to a 20 amp ESC. Match the motor to the esc. If it doesn't match up with what you picked out, move to a motor/esc combination that does, get the weight (should not be that much difference) and work it out again and get the right one.

You should be fine.

Here are some guidelines:

1. Power can be measured in watts. For example: 1 horsepower = 746 watts

2. You determine watts by multiplying ‘volts’ times ‘amps’. Example: 10 volts x 10 amps = 100 watts

Volts x Amps = Watts

Therefore,

Amps = Watts / Volts ( / = divided by ). Simple elementary math.


3. You can determine the power requirements of a model based on the ‘Input Watts Per Pound’ guidelines found below, using the flying weight of the model (with battery):

50-70 watts per pound; Minimum level of power for decent performance, good for lightly loaded slow flyer and park flyer models
70-90 watts per pound; Trainer and slow flying scale models
90-110 watts per pound; Sport aerobatic and fast flying scale models
110-130 watts per pound; Advanced aerobatic and high-speed models
130-150 watts per pound; Lightly loaded 3D models and ducted fans
150-200+ watts per pound; Unlimited performance 3D and aerobatic models

4. Determine the Input Watts Per Pound required to achieve the desired level of performance:

Example:

Model: E-flite Brio 10 ARF
Estimated Flying Weight w/Battery: 2.1 lbs
Desired Level of Performance: 150-200+ watts per pound; Unlimited performance 3D and aerobatics
2.1 lbs x 150 watts per pound = 315 Input Watts of total power (minimum) required to achieve the desired performance

5. Determine a suitable motor based on the model’s power requirements. In this case, you will need a motor/esc/battery combination for 30 amps continuous... 3 cell LiPo at 11.1 volts (nominal) is 315/11.1=28.xxx amps, round out to the higher 30 amps.

So, get your paper and pencil out and work out the details. Let us know if we can help.

M9cat

So I just bought some pusher props for my Super Cubs..I didnt know that they were counter rotating props so i just switched the red/blue wires from my motor to esc...How well or will the plane even fly right? It seems to be working just kinda scared to put into the air..

im_a_rcav8r

<p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">I am not 100% clear on your question but I will make a go at it.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">If I understand correctly, you have a front engine type airplane and you have purchased &lsquo;pusher props&rsquo;.<span style="mso-spacerun: yes"> </span>When you put the pusher props on your airplane and power up, the plane wants to got backwards &ndash; so you changed the motor to spin the opposite direction.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">Will this work?<span style="mso-spacerun: yes"> </span>Well&hellip;. Yes, sort of.<span style="mso-spacerun: yes"> </span>Is it recommended or a good idea?<span style="mso-spacerun: yes"> </span>NO.<span style="mso-spacerun: yes"> </span><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">The propeller &lsquo;pusher prop&rsquo; you have is designed to be mounted on a rear engine plane where the propeller &lsquo;pushes&rsquo; rather than &lsquo;pulls&rsquo; the airplane along.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">If you take a close look at the propeller you will see it is in-fact an airfoil &ndash; like a wing.<span style="mso-spacerun: yes"> </span>As the propeller spins it creates lift.<span style="mso-spacerun: yes"> </span>It is the lift (and some deflection) that causes the &lsquo;pull&rsquo; force or thrust.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">Again, taking a close look at the propeller you should see one side (the side away from the motor) has a slight curve (convex shape) and is thicker at the leading edge and thinner at the trailing edge.<span style="mso-spacerun: yes"> </span>The other side of the propeller is flat, or is some cases concave.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">By spinning the propeller in the opposite direction you completely defeat the engineering that went into the design.<span style="mso-spacerun: yes"> </span>It is like putting your airplanes wing on upside down and with the trailing edge forward.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">Because of the pitch in the propeller, it will deflect the air and produce thrust but it will not produce lift.<span style="mso-spacerun: yes"> </span>You will get substantially diminished performance and unpredictable behavior.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">In addition to the diminished performance, you will be introducing stress and loading to the propeller that was never intended.<span style="mso-spacerun: yes"> </span>The propeller may tolerate the stress or it may fail.<span style="mso-spacerun: yes"> </span>If the propeller fails when someone is in the path of the debris the results could be disastrous.<o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial"><o></o></span></p><p class="MsoNormal" style="margin: 0in 0in 0pt"><span style="font-family: Verdana; font-size: 7.5pt; mso-bidi-font-family: Arial">If the propeller is designed to push, let it push &ndash; don&rsquo;t make it pull.<span style="mso-spacerun: yes">


</span></span></p>

FlyM

Hello M9cat,

I know their hasn't been any activity on this thread in a while. I just happen to be looking through the "stickies" here and found your question about using a pusher prop on a front mounted electric motor for your Super Cub. You may have found that it works OK after reversing the rotation of the motor. The only problem would be if there is right thrust built into the motor mount. For a reverse rotating prop you would need left thrust to counteract the torque of the prop.
In fact, in the electric control line planes today, pusher props are preferred. They give better line tension.

Loyd

bikerbc

I ran into this thread too and thought I would mention ,.. If you move the prop from the back to the front , face it the same way and turn it the same way it will do the same thing...Standing facing the plane if the prop is turning counter clockwise with the airfoil leading edge forward , you just take the prop and move it forward , turn it the same direction face it the same way and it will do exactly the same thing...The prop dosent know if it is pulling or pushing but turning it backwards will be like when your motor sometimes starts and runs backwards .. It will , not fly apart but it won't create much pull or push either ..

CafeenMan

If your plane has built-in right thrust then turning the prop the opposite direction will make the problem the right thrust was supposed to correct twice as bad. You'll need to use left thrust to fix it which is probably a nightmare if the plane is built. As has been suggested, just get a tractor prop.

slamn sammy

Whats up? I have an O.S.91 (non pump engine) in a Grate Planes lance air, 80"wing span, l'ed like to go with a 3 bladed prop, what size prop do l need? can not make head's or tail's out of prop chart's?.............';~/

Jack_K

If you have a pusher prop but need a puller prop, it seems to me; put the prop on the motor backwards (front of prop to the motor) and run the motor in the opposite direction. That way the prop pushes toward the back of the plane, thus actually pulling the plane forward.

Jack

slamn sammy

I don't know about a fourcycle, don't think it will work installing a pusher prop on a tractor airplane. l Do Know! That if you have a twocycle that will let you rotate the front carb and baring housing to the right (standing behind the motor) 25 degrease to the right, this will change the port-timing and the motor will run backworded and you can use a pusher prop. BUT! The niddle valve will be clouse to the muffler and when your tuning you will have to be careful not to get burned. This will work! l have dun it before on pusher airplanes that l did not have a pusher prop for. (WORD) LOL...... Keep flying and out of the trees. P.S. On a electric plane it don't matter. Just do some wire swapping.

YakinCornbread

I want to switch from a 3 blade prop to a 2 blade prop on my Durafly T-28 Trojan 1100. Any suggestions of what I need to use? Thanks for any help.

slamn sammy

A
l got it figured out. You drop one inch in sizs and go yo one in pitch. Works fine, al you can Google it. LOl....... There's a chart that shows from two blade to three and four blade.

YakinCornbread

Thank you

Big-F00T

This link did not work for me - but I found this one that may be worthy::

http://www.ecalc.ch/motorcalc.php

No connection to me ---

Regards - Randy

Walkingdad

Hi all, was hoping this thread would’ve helped me, but I don’t see what I’m looking for so maybe somebody has the info I need.
I have a new build not sure what size prop I should put on it. It weighs about 600 g approximate 3 foot wingspan a 2204-1800 kvolt motor with a 30 amp ESC. Started with a six but not sure if that is correct. Don’t know if I should go larger or smaller. Any help greatly appreciated. Save me a little time, thanks again