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Old Sep 01, 2012, 04:39 PM
wood is good
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United States, CA, Marina Del Rey
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Where can a guy get an education like this, at ANY price, let alone free?
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Old Sep 01, 2012, 04:41 PM
If I build it, it will fly
United States, NY, East Rochester
Joined Jan 2012
710 Posts
*shakes hands*

That does help yes. I knew the fields could be filled in manually, & have done so hunting for props. Didn't even consider that the wizards could/should be skipped in a given situation.

Speaking of hunting for props, any plan to add in the extra shallow props? Like x3.8" x4.7"

~psguardian
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Old Sep 01, 2012, 04:51 PM
If I build it, it will fly
United States, NY, East Rochester
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Quote:
Originally Posted by loNslo View Post
Where can a guy get an education like this, at ANY price, let alone free?
Indeed!
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Old Sep 01, 2012, 05:15 PM
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IoNslo, psguardian, it (freely shared knowledge) is one of the things I love about the Internet. Information on just about anything you want to learn is out there for free - because someone who knows and loves the same thing enjoys sharing it purely for the joy of sharing. Isn't that wonderful?

It's one of those things that have been largely forgotten in the US during the last forty years - that there is much more to an enjoyable life than money and things, in fact it's more fun to share and give than to grab and cling! But thanks to the Internet, those people who still enjoy sharing knowledge now have a way of doing it, for free, with people from all over the world.

Speaking of which, if you (or a young person you know) has a math or algebra topic they could use some help with, check out the Khan Academy ( http://www.khanacademy.org/ ). There are tons of educational videos, exercise problems, and more - all of it free to use.

-Flieslikeabeagle
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Old Sep 01, 2012, 05:26 PM
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Los Angeles
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Quote:
Originally Posted by psguardian View Post
Speaking of hunting for props, any plan to add in the extra shallow props? Like x3.8" x4.7"

~psguardian
They're already in there! I put in every APC Slow Flyer and Thin Electric prop size that I could find - I didn't leave any sizes out. Same with every GWS 2-bladed prop size I could find.

These very low pitch props don't show up very often because they're really only good for hovering. For flying on the wing, those propellers are extremely inefficient, and rarely work well, so WebOCalc rarely finds them. (Bob Boucher, inventor of electric flight, genius engineer, and owner of pioneering electric RC flight company Astroflight, says these propellers are "only good for stirring paint"!)

But if you have an oddball situation where a model really needs to fly extremely slowly, these low pitch propellers will show up, because that is the only situation where they make aerodynamic sense.

Here is a snippet of code from WebOCalc, showing the list of APC Slow Flyer props contained in the program:

Code:
var apc_sf_props = 
[ 
{dia:7.0, pitch:4.0, K:0.88},
{dia:7.0, pitch:5.0, K:0.98},
{dia:8.0, pitch:3.8, K:1.15},
{dia:8.0, pitch:6.0, K:1.29},
{dia:9.0, pitch:3.8, K:1.19},
{dia:9.0, pitch:4.7, K:0.96},
{dia:9.0, pitch:6.0, K:1.24},
{dia:10.0, pitch:3.8, K:1.2500},
{dia:10.0, pitch:4.7, K:1.24},
{dia:10.0, pitch:7.0, K:1.28},
{dia:11.0, pitch:4.7, K:1.29},
{dia:11.0, pitch:7.0, K:1.2500},
{dia:12.0, pitch:3.8, K:1.2500},
{dia:12.0, pitch:4.7, K:1.2500},
{dia:12.0, pitch:6.0, K:1.2500},
{dia:12.0, pitch:8.0, K:1.2500},
{dia:13.0, pitch:4.7, K:1.2500},
{dia:14.0, pitch:4.7, K:1.2500}
];
I highlighted the low-pitch props in magenta. As you can see, they're all in there. If one of them is appropriate for the model, WebOCalc will find it and display it. But they very rarely are appropriate for any model...

-Flieslikeabeagle
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Old Sep 01, 2012, 05:35 PM
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WebOCalc only finds props that make aerodynamic sense for a model. Here is an example of a very low-pitch prop found by WebOCalc, because in this particular case this very low-pitch prop actually does make aerodynamic sense.

Notice how light and slow I had to make the model before this became a good prop choice!

-Flieslikeabeagle
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Old Sep 03, 2012, 08:18 PM
That's a funny word
NE Ohio
Joined Apr 2003
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I've read all of chuck's info and have played with this calc a few times , but I'm wondering why it doesn't find even my stock props. Here's an example where I want to replace a 1000 kv motor with a 1100 one. I merely want to see what speed increase may be with the same 9x4.5 SF prop because the plane is "plenty fast" for me right now.

http://www.flyzoneplanes.com/airplan...602/index.html

I'm also not sure how and why to change some values to get the 1:1 ratio although I do know that that's the exact ratio I use for direct drive.

I know most of the specs, but have some trouble with "flight mission" I'm calling this MM a fast sport plane. Is that right?

I dropped the 62 mph down to 52 and a 3sx1800 lipo came up which is perfect. It shows me 9x6 and 9x7.5 props instead of 9x4.5
Do I still have too fast a speed listed?
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Old Sep 03, 2012, 08:32 PM
That's a funny word
NE Ohio
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A couple of other infos I know are that it pulls 21 amps with a half full 3sx1800 pack and flies for about 12 minutes the way I fly. Since it's too fast for me I wnder if I can get away with a lot smaller motor than the 37 x 15 mm AND even get away with a 20 amp esc. I'll leave the 30 amp esc because eventually I'll want to speed it up , but I'd sure like to use a smaller lighter motor. The one on it's huge. This is a quick nimble plane.
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Old Sep 03, 2012, 10:07 PM
That's a funny word
NE Ohio
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Finally had it , but I have only 13 amps instead of over 20. I have an idea that my stock 9x4.5 prop is acting like a 9x6?

The GP SF props are pretty stiff and not like some other SF wimpy props that I've seen.
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Old Sep 03, 2012, 10:51 PM
Sic itur ad Astra
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United Arab Emirates, Abu Dhabi, Abu Dhabi
Joined Aug 2009
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Quote:
Originally Posted by gulio View Post
Finally had it , but I have only 13 amps instead of over 20. I have an idea that my stock 9x4.5 prop is acting like a 9x6?

The GP SF props are pretty stiff and not like some other SF wimpy props that I've seen.
Well if 20A is your measured current draw and 20A is the draw shown on WOC for a 9x6, then maybe it is.

Though you may be overspeeding it, that may be the reason for i,t the 9x4.5, not showing at your higher current inputs
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Old Sep 03, 2012, 10:56 PM
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Los Angeles
Joined May 2004
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Quote:
Originally Posted by gulio View Post
I've read all of chuck's info and have played with this calc a few times , but I'm wondering why it doesn't find even my stock props.
When WebOCalc doesn't find the prop you're using, usually it means that the prop you're using is a bad choice, and not really suited for the model.

In your case, the problem is worse than that. You have a motor that wants to rev up to at least 9000 rpm under load. However a 9" APC Slow Flyer prop has a maximum rpm limit of only 7222 rpm. The prop you are using is in danger of exploding at any time, because you are using it far beyond its maximum safe rpm limit.

I highly recommend that you stop using it ASAP and switch to a prop that's strong enough to handle the rpms of your motor. You cannot safely use an APC Slow Flyer prop on your particular motor and battery combo.
Quote:
Originally Posted by gulio View Post
Here's an example where I want to replace a 1000 kv motor with a 1100 one. I merely want to see what speed increase may be with the same 9x4.5 SF prop because the plane is "plenty fast" for me right now.
Please do not, repeat, do not under any circumstances use an APC Slow Flyer 9x4.5 prop, 3S lipo, and 1100 rpm/V motor together. There is great danger of the propeller exploding. A razor-sharp broke propeller blade blasting through the air at high speed is extremely dangerous.
Quote:
Originally Posted by gulio View Post
I'm also not sure how and why to change some values to get the 1:1 ratio although I do know that that's the exact ratio I use for direct drive.
WebOCalc will never show you the Slow Flyer prop with that motor and battery at 1:1 gear ratio, because it is very dangerous to use them together.
Quote:
Originally Posted by gulio View Post
I'm calling this MM a fast sport plane. Is that right?
"Flight Mission" is about how you want the plane to fly. Yes, this model looks like it was designed to be a fast sport plane, however it sounds as though you prefer it to fly much more slowly than it actually wants to fly. I will help you choose a prop to (safely) slow it down, but know in advance that it will not fly well at low speed - it isn't designed for that.
Quote:
Originally Posted by gulio View Post
It shows me 9x6 and 9x7.5 props instead of 9x4.5
Do I still have too fast a speed listed?
Yes and no...the 9x7.5 APC Thin Electric is the propeller that really suits what the model wants (which is to fly very fast). The 9x6 APC Thin Electric will slow down the model, and it won't fly quite as well, but it might make you happier, since it is almost too fast for you as it is.

If you want to slow it down as much as possible, use an APC 10x5 Thin Electric. Current draw will be way down (maybe 16 amps at full throttle), but you will still have enough thrust for long vertical lines. Top speed will be around 40 mph, which is really much too slow for this model, but it sounds like that's what you want right now. The model will be a little sluggish and fly a little nose-high, but it will fly.

When you're ready for more speed, put on that 9x7.5 APC E. That is the prop that will bring this model to life, and let it fly the way it's supposed to fly!

-Flieslikeabeagle
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Old Sep 03, 2012, 10:58 PM
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Los Angeles
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Quote:
Originally Posted by sparks59 View Post
Though you may be overspeeding it, that may be the reason for i,t the 9x4.5, not showing at your higher current inputs
Bingo! Sparks gets it in one!

-Flieslikeabeagle
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Old Sep 03, 2012, 11:02 PM
Sic itur ad Astra
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United Arab Emirates, Abu Dhabi, Abu Dhabi
Joined Aug 2009
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Quote:
Originally Posted by flieslikeabeagle View Post
Bingo! Sparks gets it in one!

-Flieslikeabeagle
F.A.B. F.L.B!

My reply was not nearly so full, or eloquent as yours though

sparks
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Old Sep 04, 2012, 07:06 AM
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Joined Aug 2012
34 Posts
Hi!
I'm new to RC, and wanted to start with the Bixler from HK. I've ordered a NMT 2836 2200kv motor, 2200mah 3s battery, and the HK 6S radio.

I'm very confused about the propeller, as this is a pusher, and it is limited to a certain size. I haven't ordered the plane just yet, but I've started with the electronics (guess I went a bit backwards there...)

Anyways; I think the original propeller is a 6x4 APC. What kind of thrust etc. can I expect? Will I be able to do FPV with this plane?

I'm fairly sure it will be 1kg (35 ounces) when everything is installed. As I want a camera + landing gear, as there is a lot of tarmac, and a bit short on parks nearby.
The full landing gear should weigh less than 100g. I bought the FPV landing gear and a simple tail wheel which can be controlled by the rudder.

What do you think? Have I ordered the wrong parts?...
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Old Sep 04, 2012, 08:16 AM
wood is good
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United States, CA, Marina Del Rey
Joined Jun 2012
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There is a thread discussing the Bixler/motor here:
http://www.rcgroups.com/forums/showthread.php?t=1703235
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