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Help! lock the prop horizontal?

#1
Hey all, I am getting tired of breaking props on perfectly good landings and someone suggested that there is a way to spoof the ESC into locking so it will be horizontal. Does anyone know how to do this?

thanx
 

evranch

Active member
#2
Not with a regular motor/ESC combination, there is no way for the ESC to know the position of the prop. The motor has a large pole count and stopping on a particular phase could be in one of many locations.

There was talk of stopping the rotors in-line with the fuselage in early quadplane discussion, to minimize drag, but I'm not sure how they were planning to do this. You would need to sense the prop rotation with a hall sensor or similar.

I rarely break props on belly landings, even at -15C. They tend to just tick out of the way and end up horizontal anyways. I cut throttle early and glide in as it takes time for the prop to spin down even if you have the ESC brake enabled. What brand of props?
 
#3
What brand of props?
The stuff FT sells.

I break one every third or fourth flight even with a good landing. I mean I expect to break one crashing but it kind of irks me to make a decent landing and then see the prop broke.

If there is nothing I can do to lock it you have any other suggestions other than adding gear?
 

quorneng

Well-known member
#5
If all else fails how about a folding prop with the ESC brake "on"?
Even if the prop does not fold completely to lie flat next to the fuselage (like it does on gliders) it will still stop turning and at worst act as a skid but you do have to get good at doing glide approach and landings.
 
#6
If all else fails how about a folding prop with the ESC brake "on"?
Even if the prop does not fold completely to lie flat next to the fuselage (like it does on gliders) it will still stop turning and at worst act as a skid but you do have to get good at doing glide approach and landings.
Okay, that is an idea, but how do I even brake with the ESC?
 

quorneng

Well-known member
#8
FMf
Virtually all plane (but not multi copter) ESCs have a "brake" option which stops, or rather it rapidly slows down, the prop. You either need a suitable programming card or the ESC can be 'programmed' using the throttle stick if the method is included in the instructions.

I must say I belly land (on grass) virtually all my planes and have only broken props as the result of a true crash.

What is your plane and do you have the motor power on during the actual landing?
 

Bricks

Well-known member
#9
Are you sure that your break is not set in your ESC by accident? Way to check is turn everything on and try and turn the prop by hand feel how hard it is to turn. Then unplug the flight battery and turn the prop by hand and see if you feel a difference in resistance. If break is on when going from full throttle to off the motor will stop very quickly there will be no free wheeling.
 
#10
FMf
Virtually all plane (but not multi copter) ESCs have a "brake" option which stops, or rather it rapidly slows down, the prop. You either need a suitable programming card or the ESC can be 'programmed' using the throttle stick if the method is included in the instructions.

I must say I belly land (on grass) virtually all my planes and have only broken props as the result of a true crash.

What is your plane and do you have the motor power on during the actual landing?

I'll have to have a look see about finding a programming card. As is they freewheel with the power off.
 

IanSR

Active member
#11
What is your make of esc? Usually there is an instruction manual for beep programming, basically you attach the flight battery with the throttle full and listen for the appropriate set of beeps or musical tones, when you hear the one you want, pull throttle to zero and you've chosen that setting, so in the case of the brake, you would turn it on (and repeat the procedure to turn it off).

Take your prop off obviously lol
 

quorneng

Well-known member
#14
The ESC brake is not mechanical but electromagnetic so has much less effect at slow or no rotational speed thus the prop can be relatively easily pushed out of the way in either direction, however if the prop is both truly vertical (rare) and stationary then it is quite likely to break regardless! ;)

A windmilling prop on the other hand has inertia so if a blade is approaching close to its lowest point at the point of ground contact it is much more likely to 'dig in' and break. It thus becomes a matter of luck as to whether the windmilling prop is at a "safe" rotational position or not.
To be fair the prop is more likely to be at a safe position than not at ground contact but the faster the prop windmills the more likely a break becomes.

The above is of course just my own opinion and preference based on my own flying.
 

HilldaFlyer

Well-known member
#15
Way back I used to break propellers on every landing... these were the slowfly. Since then I've been using APC and rarely do I break a propeller. However, I have bent a few motor shafts. My advice... if you're doing slow fly, then a prop saver should help. Also, if you program your ESC to brake then there is a chance the propeller will stop horizontally, but without a brake, you will always have a propeller strike because it is still spinning. I've recently programmed all my ESCs to brake.
 

mayan

Well-known member
#16
I personaly fly belly landers and used to break a prop every 3rd or 4th landing like you. I changed a field and make sure to land on tall grass, makes sure I don't break a prop or the airframe. I do find my self land on dirt roadways but also then barely break a prop. What I do on landings is genetly drop throttle looping in circles to help lose speed until I cut the motor dead about a meter to the ground leveled torwards my intend landing location and glide the plane down.

When I do break a prop I tend to look at the bright side, "better to break a prop than break a motor, ESC or god forbide punchure a battery."
 

evranch

Active member
#17
Looks like FT carries the regular brands (APC/Eflite/Parkzone) which should all be fine. I usually run APC props and recently have been trying out Tower Pro as they have been carrying some at my shop. So far the Tower Pro props are both cheap and tough as nails - I have one that has now been through 4 nose-in, full throttle crashes.

I cut my throttle way earlier than 1m off the ground, I would say 50m back on final. I started with gliders back in the day, so I trim all my planes for a good power-off glide and coast them in. Fly a circuit lap like you were flying at the airport, drop your airspeed, drop your altitude, line up your final approach and hit your stall speed as you hit the ground. Get to know your glide slopes and stall speeds and you won't break any more props.

Another thing is you cannot belly land in a tail-dragger attitude on the "front wheels", the prop will contact the ground hard. Spinning or not, the angle is bad and the leverage can break the blades. Land as if you were on tricycle gear with a good flare. Back of the fuselage touches first, then lay the front down.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#18
Just to be a little different I do not use ESC braking on any plane. I fly belly landers very often and They include HK mini Saturn, HK reactor, KFM wings, (these run 3 blade props), :The Flying Wing",( An FT Gremlin style flying wing), Numerous Tiny Trainers and derivatives, (including the SpiTTT), and recently a Quick Trick rebuild using a 9x5 SF prop. I cannot remember the last time I actually broke and needed to replace a propeller due to a belly landing.

Add to this a seeming myriad of maidens for the planes I build and pass/sell to other users.

The landing surface used here is normally a manicured hard packed sporting field and not all of them, (the belly landers), land slowly.

All I do when landing is to level off at around one foot in altitude and cut power. A gentle settle onto the ground horizontal sees the prop, (still windmilling), to tap the ground and bounce out of the way before the plane settles onto the ground where friction brings the plane to a rapid halt. I must have done it successfully many hundreds of times without prop loss, even in rather windy and gusty weather.

Landing in tall grass can cause the prop regardless of its position to get caught on the grass and the plane to continue, (a break will eventually occur). Landing in a nose up attitude can cause the nose to impact rather sharply as the tail hits the ground first and acts as a sort of leverage/hinge point for the plane to rotate its fuselage nose down at higher than expected speed. This can actually spear/dig the prop into the ground and the result can easily be a broken prop.

The key to reducing or stopping prop breakage is to do properly thought out and controlled landings and to use decent quality props. OHH, and also do not use 3 or more blade props on a tractor belly lander, on pushers it can be ok as long as the motor is mounted high enough to allow only the prop tips to contact the ground.

Just what works here!
 

CarolineTyler

Well-known member
#19
I definitely break more props in cold weather. Broke one on Wednesday last week and it was the most gentle of belly landings. Looking forward to warmer weather! Not found a big deal of difference on braked or non-braked ESCs when it comes to prop breakage but a braked prop really seems to cause less drag when gliding.