Prop saver or no?

Tactical Ex

Senior Member
I want the community's opinion on prop savers. I started off in this hobby on fixed wings and using prop savers but they have been the biggest problem on the field. I often find myself replacing O-rings, watching props fly off the motor in the air and hearing the low pitch buzz alerting me that the prop was off-center. I burned through all my O-rings and I hardly ever get the prop centered so there is a lot of vibration and turning at higher speeds will sometimes dislodge the prop from its center and it will rotate wrong until I go fast and strait. In an act of desperation I actually tried using a large and strong rubber band and I was able to wrap it in such a way that it was balanced/centered better than 3 O-rings and if the rubber band was without flaws it is hard to break.

Let me first say that I use the proper size hub adaptor (or closest to proper) and I use at least 2 and sometimes 3 O-rings overlapped to keep the prop in place. Even at that ... prop savers frustrate me to the point I'm considering going with an option like this ...

http://www.hobbyking.com/hobbyking/store/__16579__Propeller_Adapter_Colet_Type_3MM.html

... my concern is breaking props. I almost always land with the wheels down even when it is less of a landing and more of a crash but the gear always folds with the rubber band and the prop touches the ground and bends a bit on the prop saver. I'm worried that I will end up bending a shaft and breaking a lot of props if I go with a more dependable prop attachment method.

I want to get some serious strong landing gear like the kind with the aluminum struts and see how my landings fair with those and maybe I will be more comfortable with the prop collet.

At any rate please share your opinion and/or suggestions!
 

dwardio

Member
It really depends on the motor/prop combo + personal choice. I use prop-savers (which should really be called "shaft-savers") on my foamies and combat aircraft which are all belly-landed, as I'd rather replace a $2 prop than a prop, shaft, &/or motor. My higher-performance aircraft all use prop adapters or collets to hold them in place at high speeds.
 

Tactical Ex

Senior Member
Right now I am using a NTM 2826 1200kv motor with a 8x6 prop on a 30A ESC for my Bloody Wonder, FT Flyer, modded Versa Wing, all of which are on the heavy side.

I have to baby the Flyer and BW on maneuvers otherwise I could blow out my O-rings or rubber bands and loose the prop in mid-air. I think the Landing gear is the issue. I just need to get a more solid strut setup and do a bit better not nosing to the ground. All of the problems I have been having in the air are related to the insecurities of the prop saver so I think I will just get the adapter and make sure my gear will hold on landings.
 

rockets4kids

Senior Member
How big are the motors you are using? Prop savers work much better on smaller motors than larger ones. 24 gram motors are the effective limit for prop savers in most cases. You can use them on larger motors, but the problems you are experiencing increase dramatically above that.

And as was mentioned, they should more properly be called shaft savers than prop savers, even when used on motors less than 24 grams.
 

Tactical Ex

Senior Member
I am using a NTM 2826 1200kv motor. Is that too big? I don't know the gram weight. I didn't know there was a size limitation but it makes sense. I am having better luck with carefully wound rubber bands at this point.
 

dwardio

Member
Yep-- that's too big (~58g) for a prop-saver. I have the same motor on my FT-22 (to be maidened this weekend I hope). Did you get the "NTM Prop Drive 28 Series Accessory Pack?" It's a couple of bucks and contains the adapter to mount the prop on the "right" end of the motor as well as the prop adapter/spinner.
 

Tactical Ex

Senior Member
Yep-- that's too big (~58g) for a prop-saver. I have the same motor on my FT-22 (to be maidened this weekend I hope). Did you get the "NTM Prop Drive 28 Series Accessory Pack?" It's a couple of bucks and contains the adapter to mount the prop on the "right" end of the motor as well as the prop adapter/spinner.

Figures it is too large, I just ordered a 5 pack of 3mm prop adapters. Now I just got to get my landing gear in order and become a better pilot :). I didn't get the accessories pack (got the motor on ebay for less than $15 + free shipping). From the pictures on HK the acc. pack looked like it had a "replacement" shaft and not the reverse so that is good to know for future purchases. What I did do is take the shaft from 1 of my 2 burnt out motors with the same shaft diameters (the was an experience I don't want to repeat because those clamp washers are so easy to loose...), they are a little short but only by about 3 or 4mm.

FYI, little trick I found to reduce the chance of loosing those buggers is to cover your hands with a large, clear, plastic zip lock bag and work on it in there.
 

rcspaceflight

creator of virtual planes
I started with prop savers and quickly learned to hate them. So I switched to a grub screw prop adapter and quickly learned that grub screws strip out aluminum quickly. So I went to collet prop adapters. Which I eventually learned that prop adapters can kill motor shafts. But I don't plan on using a prop saver ever again. I think it's worth the risk to my motors. But I'm also focusing on pusher planes and a twin engine plane that keeps the props/motors protected in a crash.
 

Corbarrad

Active member
I'm flying almost exclusively tractor planes and hilariously the only prop I've broken so far was on my Hawk Sky (which is a pod-pusher design if anyone here hasn't heard of it) and I broke that prop hitting another plane I was trying to get footage of.
I've also replaced a prop on my BF 109 FunFighter because of stress marks.
Prop savers are propably fine for very light, very slow planes that use relatively fragile props. I don't thing anything from flite test qualifies in that category.
 

Tactical Ex

Senior Member
Got my stronger gear situated. Started a thread on it here. Now hopefully the only parts of mine plane touching the ground are the landing gear and not my prop.
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
Prop savers, IMO, are not only just fine but prefered for fixed wing motors less than 100w, and I've safely used them on motors up to 150W . . .

. . . But: Most prop-saver o-rings sold with porpsavers are COMPLEATLY inappropreate for the application. In most cases they have insufficent stretch to hold on tightly and are frequently too large to more than lightly hold the prop on.

Props savers DO NOT WORK if you do not use them correctly. That means -- right prop, with the right band on the right motor.

The prop itself needs to fit flat on the base of the propsaver. It also sholdn't have any lateral play between the centering shaft and the prop when it's pressed together with the band. If the prop comes with spacers that "almost" fit, go a size low, instal the spacer and ream it out until it fits.

The right band will be stretchy and *HARD* to put on. If it's easy for you to get on and off, it'll be easy for the motor to throw the prop off. Rubber/silicone tubing used for excercise bands can be cut into 1/4" slices that make great bands. It can be hard to find, but Theraband "blue" tubing is ideal and a foot of tubing can make 40-50 bands.

The right motor is a medium to low powered motor. The Blue Wonder/2730 motors are ideal for propsavers(~50W on 2S, ~85W on 3S), and can power most of FT's small to medium airframes.

One exception is multirotors. Never. Even if you're running low powered motors, the props aren't just your thrust, they're your control surfaces. Prop savers will slip while changing the speed of the prop, adding slop to the control. You might not be able to notice it, but every bit of slop in control, whether it be this, ESC ROMs, slow control boards, or weak sensors, takes a little something away from how responsive and well behaved the MR is. slippage in props is an easy one to fix with the right adaptor, and cheap too.
 

Tactical Ex

Senior Member
That's good advice Dan, especially for Multi-rotors. I'm glad I bought a 5 pack, 2 for my power pods and 3 for my future tri-copter.
 

Tactical Ex

Senior Member
Well, you all were so right. I slammed my BW into a pole today while flying with a friend. It is becoming custom for me to brutalize my plane on the first flight of the day. I snapped 1 shaft in half and bent the other motor shaft and need to buy more. I also broke 3 of the 5 prop adaptors (I think they were cheapo). That being said I love not using the shaft-saver. The plane is so much quieter and I don't have to second guess the abilities of the plane in the air. Thanks for all your help. If you have any suggestions on cheap 3mm shafts for the NTM 2826 and some stronger 3mm adaptors I would be very thankful.