Preventing prop / firewall breakage on belly landers

[randyrls]

OK: I am tired of breaking props and/or firewalls when landing on our grass runway. Prop savers cannot be used with any of the power pack motors that FT supplies. There is a prop saver setup for up to 5mm shafts, but the power pack B FT motors have a 6mm shaft. I've come up with number of ideas. Which one sounds like the least work and greatest chance of success in eliminating the breakage?

1. Add a landing gear wire below the fuselage to keep the prop clear of the ground. Like a wheeled landing gear but running lengthwise on the bottom of the fuselage. like \_____\

2. A separate servo that has a pushrod with wire insulation on the end that sticks into the prop disk. Chop the throttle, then flip a switch and the "lock" servo stops the prop from free wheeling.

3. A larger version of the prop saver that fits the motor shaft. I've already spec'ed out the threading and shaft dimensions. I have a metal lathe and I know how to use it! This would likely need several iterations to get a good result.

 

[tomlogan1]

OK: I am tired of breaking props and/or firewalls when landing on our grass runway. Prop savers cannot be used with any of the power pack motors that FT supplies. There is a prop saver setup for up to 5mm shafts, but the power pack B FT motors have a 6mm shaft. I've come up with number of ideas. Which one sounds like the least work and greatest chance of success in eliminating the breakage?

1. Add a landing gear wire below the fuselage to keep the prop clear of the ground. Like a wheeled landing gear but running lengthwise on the bottom of the fuselage. like \_____\

2. A separate servo that has a pushrod with wire insulation on the end that sticks into the prop disk. Chop the throttle, then flip a switch and the "lock" servo stops the prop from free wheeling.

3. A larger version of the prop saver that fits the motor shaft. I've already spec'ed out the threading and shaft dimensions. I have a metal lathe and I know how to use it! This would likely need several iterations to get a good result.

Try Crash Test Hobby. They make a line of prop savers that top out at 5mm but you can drill it out for 6mm. I've used several in different sizes and they work great for me. You will have to scroll down a bit to get to the prop savers.

http://www.crashtesthobby.com/store.html

 

[Merv]

...Which one sounds like the least work and greatest chance of success in eliminating the breakage...

Not sure what type of props or what size you are using. I’ve had great results with APC props. You might also try a smaller prop, may need to spin it faster. It’s tough to eliminate prop breakage, but a better prop might significantly reduce the frequency.

I’ve got a pusher Versa wing that likes to go fast, mostly run 5 & 6 inch props. With APC type props, I break very few belly landing.

 

[quorneng]

Assuming the nose profile of the plane is appropriate you are unlikely to break a folding prop particularly if you set the ESC brake to "on".

Indeed have you tried simply setting the ESC brake on. A fast wind milling prop is much more likely to break that one that is stationary or turning slowly. Remember the ESC brake is dynamic not "rigid" so the prop can still be easily flicked out of the way unless it is exactly vertical at the point of impact.

 

[Bo123]

Assuming the nose profile of the plane is appropriate you are unlikely to break a folding prop particularly if you set the ESC brake to "on".

Indeed have you tried simply setting the ESC brake on. A fast wind milling prop is much more likely to break that one that is stationary or turning slowly. Remember the ESC brake is dynamic not "rigid" so the prop can still be easily flicked out of the way unless it is exactly vertical at the point of impact.

I was about to auggest that.

 

[randyrls]

Thanks for the info. I ordered some of the larger prop savers. I have both a normal Eagle with the motor in the nose, and I want to build a F22 with the pusher prop in a slot in the middle.

I don't believe the FT ESCs can be programmed.

 

[danskis]

I don't like the way planes look with wheels so very few of my planes have wheels. When I first started I would break a prop every flight. Now I go for 10 or more flights without breaking a prop. The key is to flair the landing at just the right time. It can be done but its expensive to learn. Most of the FT planes float pretty slowly if you dead stick the landing. Just make sure to complete your last turn before chopping the throttle.

If you're breaking firewalls you're coming in much too hot. IMHO

 

[Ratcheeroo]

Make landing gear.

 

[The Fopster]

Can’t remember the last time I broke a prop, but it used to happen pretty much every day I flew. No idea why it doesn’t happen anymore - for the record I mainly use APC or Master Airscrew props and I have got better pilot skills since I started, but even so? I usually have prop brake set - worth a try?

 

[bwarz]

I'd have to say for me cutting the throttle before a 'cleanish' landing has not broken a prop in a long time. Early on having throttle still on even a little was hit or miss, especially with higher RPM motors. I use mostly APC props, and just the el-cheapo orange props on my mini scouts for my kids. BTW hitting the field cart used to bring planes to the field breaks props - just sayin' - might be recent experience

+1 on the firewall breakage = coming in too hot

 

[Piotrsko]

If breaking props is the issue, go with nitro engine props, boil them for 15 minutes, and break something else instead. I have used a top flite 10-6 prop for the last 50 years

 

[checkerboardflyer]

A lot of good comments above. Years ago the old time free flight models were often fixed with a single wheel landing gear. Free flight, not R/C, so they landed how they landed which often meant broken props. The single wheel prevented breaking props. See the picture below. Another option is to build a model with the motor mounted above and rear. Like the FT Tenet. It can be built as a trainer type or a more aerobatic version. Visit my blog for more tips for foam board R/C modelers. https://foamboardflyers.com

 

[Gray Harlequin]

I agree with some of the posters above. Prop brake has worked well for me. No broken props on belly landers yet.