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Stop the prop horizontal

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Old 09-11-2009, 11:40 PM
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Mike Connor
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Default Stop the prop horizontal

I am setting up my first electric and it is a hand launch belly lander. Is there any way to make the prop stop horizontal so it doesn't break during landing?

Edit - Also, should I be concerned about grass and other stuff getting in the motor?
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Old 09-12-2009, 04:12 AM
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Default RE: Stop the prop horizontal

What you need is a Prop SAVER (not a Prop Adapter). It folds and bends instead of breaking your prop on contact. I can't tell you how many props I broke before I found out about these cheap things.

Look about half way down the page (see LINK below) for Prop SAVER. I don't know what size shaft your motor is. Measure it. It probably is a 3 mm, though. I'd also get some replacement shafts as long as you are ordering. They are cheap and make old motors new.

I do not know of a way to stop an electric prop horizontally other than watching the plane as it lands and giving the motor a slight touch of power. Hard to do if you are new and are just concentrating on getting the darn thing down safely. On a fuel plane, you can use the engine's compression point to stop a prop horizontally (sometimes! ).

Crashes are inevitable. Preparing for them is mandatory. regards, Rich

http://lazertoyz.ncweb.net/PropAdapters.html
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Old 09-12-2009, 09:42 AM
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Default RE: Stop the prop horizontal

I have been in RC a long time but new to electrics. I will be testing 2 different motors on this airframe and both have a 3.2mm (1/8") shaft. I didn't see one for a 3.2mm shaft but may look around. Are they good for high rpm? One motor will turn a 4.5 x 4.1 at about 52,000 rpm and the other will turn a 6 x4 about 34,000 rpm.
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Old 09-12-2009, 10:46 AM
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Default RE: Stop the prop horizontal

Can't help re "which motor is correct"... I am learning too. I am sure a knowledgeable reader will answer on that soon here.

Now, regarding the propsavers...if you buy a 3mm one, you can always drill it out to fit 3.2mm regards, Rich
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Old 09-12-2009, 11:00 AM
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Default RE: Stop the prop horizontal

Prop savers and props spinning at 30,000+ RPM do not go well together. With an eyeball nearby the results can be quite spectacular. The rubber O ring that is used to attach the prop will degrade with time and tend to split. For a Zagi type plane you need not worry. When you clip the prop during landing it will gently swing away. It will not break, most often not at all. So just use the usual prop adapter.

What motor to use depends on what you want (insane speed or crusin' about), what battery packs you want to run (how many cells and what capacity). If you are running a 3S set up and you got a 28mm motor then the one turning at 52,000 RPM with the 4.5 x 4.1 is a pretty hot motor (high KV) whilst the other at 34,000 is hot enough too. The faster motor may not be practical because the pitch speed (about 200 mph) exceeds the the speed of the flying wing fuse. Hence, its just wasted.

What are the motors you have? Just make sure it does not kill the batt or the ESC or the motor itself.
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Old 09-12-2009, 11:19 AM
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Default RE: Stop the prop horizontal

Quote:
ORIGINAL: tIANci

Prop savers and props spinning at 30,000+ RPM do not go well together...
What are the motors you have? Just make sure it does not kill the batt or the ESC or the motor itself.
After looking at what a prop saver is, I agree it will not work for me.
I am testing an Arc 28-47-1 4250Kv and Arc 28-47-1.5 2800 Kv motor with a 4S 4000mAh battery (edit - ICE 100A ESC) on a 42" wing that will weigh RTF about 42 oz. The 2800Kv was out of stock when I started so I bought the 4250Kv to play with. Now the 2800 is in stock and I will order one Monday. The 2800 has been tested with good results on the heavier "Ritewing Demon" 40" wing with more frontal area. The high rpm and small props of the 4250 may not be my best bet but should be interesting. These motors are only $55 each.
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Old 09-12-2009, 11:19 AM
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Default RE: Stop the prop horizontal

tIANci is correct re the high speed prop and the slower speed prop saver devices. I only focused on saving the prop..but not the big picture. Sorry.

One thing that a number of guys around here have done is add Coroplast or foam "skids" that raise the bottom up just enough to clear the prop from the ground. One time I added two pieces of electrical wire-ties and glued them in in a "bowed" fashion. They added almost no weight; had little air resistance..and yet added some height to the rear of the plane upon landing. regards, Rich
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Old 09-12-2009, 03:48 PM
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Default RE: Stop the prop horizontal

Just a thought that may not be suitable but I know on powered sailplanes the use folding props that have to stop horizontally. To do so thay set the brake on ESC. Check in the sailplane forum to get info.
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Old 09-12-2009, 10:01 PM
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Default RE: Stop the prop horizontal

Don't worry about the prop. On a normal landing it will just move out of the way as it touches down (assuming throttle closed.)
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Old 09-12-2009, 11:02 PM
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Default RE: Stop the prop horizontal

I wont worry about the prop and will hope no debris gets in the cooling holes. Thanks for the replies.
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Old 09-29-2009, 06:41 PM
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Default RE: Stop the prop horizontal

I am not familiar with that particular brand of ESC, but I have E-Flites that are programmable. You can program in "Braking" to the ESC and it will stop the prop from turning when the throttle is cut all the way. I had damaged numerous props on one of my planes during landings and put in medium braking, no more issues. It does not guarantee stopping horizontal, but the fact that the prop stops turning helps a lot. It also reduces power off drag and provides a better glide ratio.
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