Prop hub void - would you fill for 4-bolt drilling?
 

I have a DLE 30 with a 4-bolt propeller hub. The hub of the propeller I would most like to use - a Master Airscrew 16 x 8 3-blade - is not solid in the back:



https://farm3.staticflickr.com/2858/...a135689e82.jpg



I am wondering if I could fill the void with epoxy, then drill the bolt holes through that.





Thoughts?

If you really like the Master Airscrew propellers, then my suggestion to you is to purchase the single bolt hub adapter from Valley View for the DLE30. I have one of these on my PTE36R and it really makes life easy as far as prop selection and changing, well worth the investment.

Hey Barry, I have a single bolt adapter (SBA) for my RCGF 32 and I like it fine. I bought one for the DLE 30 and it sheared the bolts and threw the prop during its maiden flight.

https://farm9.staticflickr.com/8691/...9bddf725a4.jpg


VVRC very kindly sent me a replacement, but when I put it on it showed excessive runout.

DLE 30 - Single bolt prop adapter - face runout

DLE 30 - Single bolt prop adapter - shaft runout


I let them know; after a reply email I checked the fit and found the cause.

As you may remember, to attach the SBA you have to make a nut out of the crankshaft extension by cutting off most of the shaft.

http://www.rccanada.ca/rccforum/atta...ine=1431089091


I discovered last night that the nut is too long, interfering with a flange on the back of the SBA and preventing the rear of surface from mating flush with the face of the prop hub.

http://www.rccanada.ca/rccforum/atta...ine=1431089091


I was able to shorten the nut by removing a portion of the flange at the bottom.

http://www.rccanada.ca/rccforum/atta...ine=1431089091


Now the SBA fits properly - the flange fits in the bore of the prop hub with no wiggle room that I can see.

IMHO Master Airscrew and APC props with gassers don't mix. Filling voids with epoxy is a receipe for disaster. Go with Zoar, or some prop with a solid hub.
I fly gas and loved APC props but not on a gasser.

I totally agree. Not to mention, the hubs of the APC props are quite brittle.. albeit when new and untouched other then a proper reaming, they're the strongest... but you definately don't want to drill any holes in that hub.. backfilled or not... If that hub were drilled, theres a likely chance of that prop throwing a blade.. very likely. APC props are among the best, but only when kept in totally pristine condition... Either go with another prop, or go with the single bolt adapter.. but I don't recomend drilling your APC for a 4-bolt mounting.

Just a note of experience . I had the same 3 blade prop on a DLE 30 with the single bolt adapter and this prop exploded in flight . I thought well that was odd so after repairing the trashed engine box and remounting the engine I tried another of the same prop and guess what happened again . I would not recommend using these props on a gas engine and I certainly wouldn't drill holes in the hub.

As mentioned in another thread, thankfully I have never experienced one of these props exploding but I witnessed this happening twice on a friends airplane. The engine was one of the original YS 120's and on the first occasion, the prop exploded and the whole engine was ejected from the plane. He made a very nice landing without the engine which was quite amazing to me considering the CG location w/o and engine. About a year later, he experienced the same thing again and this time, the engine separated into two pieces with the back half remained with the airplane and the front half was ejected into a field never to be seen again! Another good landing and the plane finished its life quite happy with a 2 stroke Webra 120 and wood props! Unmodified these props can have issues so why modify them and risk even greater issues. I'm sure they have their place on some planes but not on high performance engines or in a modified form.

You had to modify the engine? (Which voids any warranty) to run an APC prop which really shouldn't be on a gasser anyway?
I love APC when I flew glow. The whirling razor shouldn't be on gas IMHO
good luck