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Jul 11, 2018, 12:22 AM
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Quote:
Originally Posted by balsa or carbon
Yes , with enough speed . It may be very difficult to get enough speed at launching , perhaps a catapult launcher would help .

But my biggest concern with trying to make a hotliner out of a chuck glider would be the strength of the styrofoam airframe .
Can you please explain. I dont know which motor you perferred and a 5x5 or 6x4 should give enough speed with a firm hand launch.
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Jul 11, 2018, 07:18 AM
treefinder
springer's Avatar
Unfortunately, you are asking us to speculate on things we don't have experience with. I would bet the percentage of guys on this forum who use inrunners is in single digits. For most planes the rpm and resulting prop size of outrunner works best. Inrunners, when used in the past were usually geared down . With the proliferation of lots of different Kv outrunners no need for geared down inrunners.

Since you have a motor, I would set the plane up for it, try it with different props and go from there. Those chuck gliders seem to glide pretty well under any conditions. I would install the gear to get CG at about 25% aft of wing LE and give it a glide test over tall grass. If it glides straight and in a nice gentle arc to ground, or a flat glide, try it again with some power like quarter throttle to see if maintains flight. If that's good, power up and see what she does.
Jul 11, 2018, 07:53 AM
Jack
jackerbes's Avatar
This all comes down to wing loadings and things like that, if you can't post a link the aircraft you bought or a dimensioned drawing so that the wing area can be worked out it is really hard for you to get a good answer here.

Jack
Jul 11, 2018, 09:12 PM
Registered User
Quote:
Originally Posted by jackerbes
This all comes down to wing loadings and things like that, if you can't post a link the aircraft you bought or a dimensioned drawing so that the wing area can be worked out it is really hard for you to get a good answer here.

Jack
Wing Area = 368 sq in = 2.56 sq ft.
Wing Loading = 9.80 oz/sq ft

This is the exact measurements for the wings.
Jul 11, 2018, 09:15 PM
Registered User
Quote:
Originally Posted by springer
Unfortunately, you are asking us to speculate on things we don't have experience with. I would bet the percentage of guys on this forum who use inrunners is in single digits. For most planes the rpm and resulting prop size of outrunner works best. Inrunners, when used in the past were usually geared down . With the proliferation of lots of different Kv outrunners no need for geared down inrunners.

Since you have a motor, I would set the plane up for it, try it with different props and go from there. Those chuck gliders seem to glide pretty well under any conditions. I would install the gear to get CG at about 25% aft of wing LE and give it a glide test over tall grass. If it glides straight and in a nice gentle arc to ground, or a flat glide, try it again with some power like quarter throttle to see if maintains flight. If that's good, power up and see what she does.
I will not be gearing down, no need to the motor is well within amperage of esc and will get good thrust with a 6x4.5 prop at 55amps.

With the 540 3100kv motor I used a 6x4.5 prop on the test bench to see amps and it was 55.4 so below 60 amps. The thrust was 1638g (50.9oz). People are saying im gonna need a catapult to launch but I dont think so with the 6x4.5 prop as it is larger and pulls twice the weight of the plane. And the 6x4.5 is a "parkflyer" and works well in my other models so I think it'll fly just fine.

And from all of the fast setups I see people using inrunners and havent seen one geared down. As long as its within the amps It seems to be ok for the motor.
Last edited by brymck1901; Jul 11, 2018 at 11:32 PM.
Jul 12, 2018, 07:03 AM
Jack
jackerbes's Avatar
Quote:
..the thrust was 1638g (50.9oz)...
That is a lot of thrust from a not well identified 6" x 4.5" prop, I looked at props of about that size in the prop data at flybrushless.com

http://www.flybrushless.com/prop/search

and could not find one that could do that. Most were only capable of about half of that and that was when they were getting up to 21,000 RPM or so.

But 10 oz./sq. ft. or so is a very favorable wing loading and it won't take much thrust to get that launched by hand at that weight. It does not take much thrust at all to keep a plane like that flying once it is in the air.

Jack
Jul 12, 2018, 07:41 AM
treefinder
springer's Avatar
Brymck. I wasn't suggesting you gear yours down, just commenting about the history. Early electrics were all inrunners and brushed and had to spin fast to develop useful power. Typical airplane models (yours is not "typical") wanted large slower turning props, so inrunners got geared down. When guys started re purposing from motors the found that outrunners fit their needs better and more simply than geared inrunners (brushed or brushless).

For really high speeds, though inrunners are preferred, as they can achieve higher Kv than outrunners. So finish yours and show us the vids!
Jul 12, 2018, 10:01 AM
Registered User
Quote:
Originally Posted by jackerbes
That is a lot of thrust from a not well identified 6" x 4.5" prop, I looked at props of about that size in the prop data at flybrushless.com

http://www.flybrushless.com/prop/search

and could not find one that could do that. Most were only capable of about half of that and that was when they were getting up to 21,000 RPM or so.

But 10 oz./sq. ft. or so is a very favorable wing loading and it won't take much thrust to get that launched by hand at that weight. It does not take much thrust at all to keep a plane like that flying once it is in the air.

Jack
Hello, the prop is an HQ carbon prop at 6x4.5 it says for quads but it gets better thrust at more amps from the APC props. And ok good I thought it would fly well at low speeds because of the glider tendencies.
Jul 12, 2018, 11:42 AM
Sokol
JureZ's Avatar
Quote:
Originally Posted by brymck1901
Hello, the prop is an HQ carbon prop at 6x4.5 it says for quads but it gets better thrust at more amps from the APC props. And ok good I thought it would fly well at low speeds because of the glider tendencies.

Ok, in summary and responding the original question : it will be very heavy.


about the propellers: do you have a Watt meter to check the propeller loading ?
Jul 12, 2018, 12:15 PM
Short bursts, Don't waste ammo
RCAV8R1964's Avatar
You may have already answered it, I just couldn’t find it. But since you have the wing area, find the cubic wing loading index for the performance you want. Work the equation backward to find out how much weight will give you that index then find your watts per pound for the performance you want. Once you have that see if your power setup satisfies the requirement.
Jul 12, 2018, 12:20 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by brymck1901
And ok good I thought it would fly well at low speeds because of the glider tendencies.
The main ingredient for slow flight ( minimum stall speed ) is "light wing loading" . Wing loading is total weight .... relative .... to wing area . The type of plane ( glider ) has little to do with it .
A heavy plane with little wing area has to go fast for the wings to generate enough lift to become/remain airborne .
A lightweight plane with a lot of wing area does not have to go as fast for the wings to generate enough lift to become/remain airborne .

Here is a plane I've made for the single purpose of flying slowly , so I made it with very light wing loading .... be sure to watch the landing at the end :


Lightweight 40" wingspan FT Old Fogey-ish (2 min 58 sec)
Jul 12, 2018, 10:49 PM
Registered User
Quote:
Originally Posted by balsa or carbon
The main ingredient for slow flight ( minimum stall speed ) is "light wing loading" . Wing loading is total weight .... relative .... to wing area . The type of plane ( glider ) has little to do with it .
A heavy plane with little wing area has to go fast for the wings to generate enough lift to become/remain airborne .
A lightweight plane with a lot of wing area does not have to go as fast for the wings to generate enough lift to become/remain airborne .

Here is a plane I've made for the single purpose of flying slowly , so I made it with very light wing loading .... be sure to watch the landing at the end :


https://www.youtube.com/watch?v=P2Xyjy3fcpE
LOL your walking next to it! Thanks for sharing man.
Jul 13, 2018, 09:39 AM
Wake up, feel pulse, be happy!
Piece's Avatar
You'll find very different opinions here in Scratchbuilt Foamies about what counts as "heavy" and "fast" than you will in High Performance where you posted your other thread. When I read that one, I assumed that the model was at least something designed for RC flying from the beginning.

My biggest concern would be the structural integrity of the plane, not the weight of the power system. Adding carbon spars is no magic cure. You could shred one of those foam gliders into confetti with a motor that's half the size of your "small" option, and frankly, it's not worth the effort to try and beef it up to go fast because the airfoil is still all wrong for speed. Way too thick, flat bottom, designed to be a fun chucky glider toy.

The best course of action would be to get a very small, lightweight electric drive to put some power on your glider, and then buy or build a more suitable model for your larger motor.
Latest blog entry: Jeti ESC resto-mod
Aug 05, 2018, 02:49 PM
Registered User
Quote:
Originally Posted by balsa or carbon
Let us know how it turns out , with video if possible !
I have abuild log going!
Aug 05, 2018, 02:50 PM
Registered User
Quote:
Originally Posted by Piece
You'll find very different opinions here in Scratchbuilt Foamies about what counts as "heavy" and "fast" than you will in High Performance where you posted your other thread. When I read that one, I assumed that the model was at least something designed for RC flying from the beginning.

My biggest concern would be the structural integrity of the plane, not the weight of the power system. Adding carbon spars is no magic cure. You could shred one of those foam gliders into confetti with a motor that's half the size of your "small" option, and frankly, it's not worth the effort to try and beef it up to go fast because the airfoil is still all wrong for speed. Way too thick, flat bottom, designed to be a fun chucky glider toy.

The best course of action would be to get a very small, lightweight electric drive to put some power on your glider, and then buy or build a more suitable model for your larger motor.
Build log is going with the 2845 2600kv and 6x5.5 prop on the chuck glider!


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