Just checking out a rumor. Has anyone ever experienced in-flight breakage with the larger black plastic props.
DYNA .... THRUST, or something ? I've got some on hand, and I'm concerned about using them. They are similar to Master Airscrew, but made by a different company.

Thanks - Jim

Hi Jim,
I remember several years ago (around 12, more or less) that larger Dyna Thrust props were proported to have shed a blade in the air now and then. As I recall, the manufacture put out some info about the importance of balance, multi bolt prop hub prop drilling, and spinner clearance. I also recall hearing that the manufacture had reconstitued the material the props were made from although I don't remember his ever acknowledging any responsibility for a potentially faulty product.

I used a Dyna Thrust 22X10 on a Zenoah G-62 in a Sig 1/3 scale Space Walker, which I fly off the water on occasion. (extended Sig !/4 Scale floats). I used the prop for several years
with no problem in both ROG and ROW configurations. Last year, the prop finally shed a blade in flight, breaking off at about 2 inches out from the spinner. Fortunately, I recognized the change in sound and shut down the engine almost immediately and was able to glide in for a smooth middle of the runway landing. At first appoearance, the model looked ok...but in reality, the vibration had torn loose almost everything inside the fuse and the wing was ready to fall off. I was very fortunate to get the model back on the ground in repairable condition.

I must acknowledge that I had not inspected the prop for cuts, nicks or deep scratches that are possible as the result of flying from a dirt runway. After the fairly extensive repairs, I started using Zinger wooden props and found an improvement in thrust. I would suggest that you need to know the age of the DynaThrust props you have on hand and not risk there use if they are very old. Further, I beleive you'll bee happier with the greater efficiency of several manufacturers wooden props unless you are talking about flying of the water In any event, the near loss of my plane was a reminder of the importance of regularly inspecting any prop for cuts, nicks, cracks along the blades and taking the spinner off to check the apparent condition of the prop hub.

It is also worth while noting that Master Airscrew has discontinued the production of their larger "plastic'' props as the result of liability issue concerns following some reported failures.
I will be checking out the use of a carbon fiber prop for my water flying in the future.

Thanks Bob, those were the same kind of stories that I was hearing. Your answer however, was much more comprehensive and enlightening. The DynaThrusts are no longer a problem, I have just relageted them to paint stirring duty.

And yes, I have been using wood Zingers 18" and over.

Thanks - Jim

I myself will never ever use another Dyna prop. Even though it is small for what these big engines run. I had it on a Magnum .91 four stroke 14 by 6 and it was turning 9800 on the ground when one blade let loose and with much luck it did not hit either myself nor my friend that was helping. But it did tear the fire wall off of the plane and hit the ground so fast we could not even see it. Sceeeeeeeeeered the heck out of us.


But I guess as others say your luck may very.

A member in my club was flying a hots with a g-38 and dynathrust prop.It shed a blade and ripped the nose off.After picking up the peices we noticed a hairline crack in the prop and it was a new prop.This was it's first flight and it's last.

Did the blade delaminate?
Why did it fail?

No they did not delaminate they are plastic and they just break without warning. BAD BAD BAD. All I know is my friend and I were very lucky not to get hurt I was only two feet from it on the side and he was behind it with a tach when it came apart. It took the tack out of my friends hand and destroyed it and the blade that came off went straight into the ground. It pulled the engine and fire wall off of the plane and onto the ground so fast I did not even see it move. Now I have seen a rattlesnake strike and this was much faster.