Originally Posted by Little-Acorn

Did another test flight this morning, as close to yesterday's test flight as I could (yes, a lot of room for error there, sorry), but this time with the APC 10x5E two-blade prop instead of yesterday's Master Airscrew 10x5 three-blade fuel propeller. This flight was exactly 21 minutes long from launch to landing, starting with a fully-charged battery. And afterward I recharged the battery, and it charged for 87 min. 56 sec. at a 1 Amp rate before clicking off "full".

Launched at half throttle, it climbed well as usual, then vertical climbed at full throttle to about 300 feet, levelled off, and did the easy-cruise thing at less than half throttle for the next 20 minutes or so, a few low-power loops to bled off altitude, finally a long glide to landing (no missed approach this time). It was as close to yesterday's "gentle" flight as I could make it. If anything, today's flight with the two-blade might have been slightly gentler than yesterday's with the three-blade, due to no missed approach and two low-power loops today instead of yesterday's three.

* Today: It used 1,466 mAh in 21 min. (0.35 hours), averaging 4.19A current flow with the APC 10x5E two-blade prop.
* Yesterday, it used 1,500 mAh in 24:15 (0.404 hours), averaging 3.71A current flow with the M.A. 10x5 three-blade prop.

Not a big difference, probably within the margin of error considering I couldn't make the flights identical (but I tried ).

But overall, it sounds like the two props give nearly identical efficiency for these "gentle" flights. At least, the three-blade is apparently NOT less efficient than the two-blade. That runs counter to intuition, but that's what the (rough) numbers seem to say.

BTW, the plane seemed to vertical-climb at full throttle just as well with the two-blade as with the three-blade. Never fell out of the climb with either prop. Also counterintuitive, but there it is. Differences between the props just don't seem that significant.

Sorry, can't believe you without any footage. Can you make a vid of at least of the takeoffs?

can someone with the knowledge please explain why the stock prop 8x7 according to the online prop calculator keeps saying it will "prop stall" ? i used stock motor specs,and tried the 8x6 the 8x7 and the 8x8 they all say the prop could stall and something about thrust being wrong. Why did they send this plane out with this prop if it isnt correct for the motor ? If i put in a 9x4.7 or 9x5 the "prop stall" error goes away. i ordered two 8x8 SF props and now find out they will be spinning to many rpm,s and will possibly prop stall whatever that means. Thanks ! wish my darn watt meter would get here !

Originally Posted by G-LO

Sorry, can't believe you without any footage.

My sympathies.

Can you make a vid of at least of the takeoffs?

I'll try to find a sucker^H^H^H^H^H^Hvolunteer to shoot with my old iPhone next time. But I'm not that great a pilot, and have had my hands full keeping it out of the trees, camera work has been lower priority so far.

Can't you sit it on the car or something as you go in the middle of the field? Oh, just thought about it..it might get stolen in the middle of one of your loops. Well, try and get a sucker one day ..ok? I would love to see your SSS fly.

Originally Posted by fastfwd

can someone with the knowledge please explain why the stock prop 8x7 according to the online prop calculator keeps saying it will "prop stall" ? i used stock motor specs,and tried the 8x6 the 8x7 and the 8x8 they all say the prop could stall and something about thrust being wrong. Why did they send this plane out with this prop if it isnt correct for the motor ? If i put in a 9x4.7 or 9x5 the "prop stall" error goes away. i ordered two 8x8 SF props and now find out they will be spinning to many rpm,s and will possibly prop stall whatever that means. Thanks ! wish my darn watt meter would get here !

Fastforward I wanted to know what prop stall was too. So I reaserh it, and found this:

https://www.rcgroups.com/forums/show....php?t=1422471

Originally Posted by G-LO

Fastforward I wanted to know what prop stall was too. So I reaserh it, and found this:

https://www.rcgroups.com/forums/show....php?t=1422471

hmmm okay, im wondering if the combo of my buddy trying to climb to fast and the STOCK prop stalling is why his fell on its nose from about 100 feet up. Just amazing to me that banana would sell this baby with a stalling prop on it. soon as watt meter gets here from ching chong china ill test stock motor with a 9x4.7 or a 9x5 apc e prop. Thanks for the info !

Does the prop stall they predict, happen only at zero forward airspeed?

How many fly that way?

Originally Posted by Little-Acorn

Does the prop stall they predict, happen only at zero forward airspeed?

How many fly that way?

from what i understand from that post it happens at launch and when going from low speed to throttle up ?
" When your model with very small high-pitched prop, screaming away, falls to the ground after a firm, level hand launch, prop is probably stalled, don't know how to measure amount of "stallage" "

A stalled prop still generates some thrust, just not very efficiently, and thus could be less than if you launched with the prop spinning just below stall speed. Problem is you need to increase RPM quickly after launch as the model will accelerate towards pitch speed quickly. Therefore, in almost all cases, it's better to launch with the prop stalled at full power, as the model should be flying when it leaves your hand already..

On high performance models, you can hear it. It's sort of a 'whoosh' sound..

A stalled prop is spining too fast in your hand. The prop does not develope enough thrust to accelerate the airplane to flying speed quick enough. The plane usually falls out of the air.

A propeller is an airfoil, like a wing, and can stall in the same way a wing does. A stalled wing loses lift; a stalled prop loses thrust. There is a pretty good tutorial on propeller basics here:

http://www.stefanv.com/rcstuff/qf200203.html

an example of what was being talked about early on in the topic here, i got an 8x8 prop, now if i had gone with what i was told in other threads the writing would be facing out,but then that would be backwards according to the drawing i got,the convex side always faces front of plane regardless if motor is on back on top or front. now if this prop was going on a plane where prop is on front of plane then yes writing would be facing out away from motor but on the sss the writing is is facing motor. Still facing front of plane but not out away from motor ..

Originally Posted by fastfwd

an example of what was being talked about early on in the topic here, i got an 8x8 prop, now if i had gone with what i was told in other threads the writing would be facing out,but then that would be backwards according to the drawing i got,the convex side always faces front of plane regardless if motor is on back on top or front. now if this prop was going on a plane where prop is on front of plane then yes writing would be facing out away from motor but on the sss the writing is is facing motor. Still facing front of plane but not out away from motor ..

This will always be a continuing issue, but, as a general rule. the writing stamped on the prop mostly faces the direction of travel of the aeroplane.
That is to say, if the motor is mounted on the front, the writing on the prop will face away from the motor.
If the motor is fitted on the rear, the writing will face the motor.

And, another way,,Standing at the front of the model, visualise the props spinning anti clockwise regardless of the motor being on the front or the back and with the writing on the prop facing you.

Long ago in the Easystar thread, this came up. Some people were having a tough time figuring out which side of the prop was convex and which was concave. So I wrote out a simple try-it-and-see method:
https://www.rcgroups.com/forums/show...4#post18710147

Originally Posted by Little-Acorn

Long ago in the Easystar thread, this came up. Some people were having a tough time figuring out which side of the prop was convex and which was concave. So I wrote out a simple try-it-and-see method:
https://www.rcgroups.com/forums/show...4#post18710147

yea i have read others saying that, someone posted this pic here and it helped alot,but some of my props it is hard to tell what side is convex or concave.

Originally Posted by kaptondave

A propeller is an airfoil, like a wing, and can stall in the same way a wing does. A stalled wing loses lift; a stalled prop loses thrust. There is a pretty good tutorial on propeller basics here:

http://www.stefanv.com/rcstuff/qf200203.html

nice info there thanks, my bookmarks on motors,props and esc setup is getting pretty big

Fastfwd, you have any NTM prop adaptors for you New motor? If not, do you know these folks?

http://www.planeinsanerc.com/index.php?PageID=12