Hi Butch,

 A thought occurred to me regarding the prop blade and hub and I can't

seem

to get it out of my mind, so thought I would send it for your

consideration.

    As you know there is an "coning" effect produced as the tips/ends of

the

blades want to pull forward while spinning while the hub end of the

blade is

anchored (by the hub).  My question regards the possibility of the

coning

forces at the tip of the blade causing the hub end to bind.  It would

seem

that to preclude the possibility of these forces causing the end of the

prop

journal from being forced to the side and contacting the hub ( and

possibly

binding) that the design would need two ball bearing races in the

hub/prop

journal separated by a couple of inches.

    Now that I have that off my chest, I will await your illumination of

my

befuddled brain {:>)

Ed Anderson

****************************************************************************
****

Hi Ed / Gang;

I must apologize for my tardiness in answering, seems I have caused a

rather

tremendous ruckus-scramble after announcing my retirement, so I've been

swamped

with FINAL project closings......I must be pretty good at what I do

since they

refuse to "Let go" :)

Ed there's a short answer to your concern:   IF it could happen, it

would just

prevent you from pitching the Blades further, and they would freeze/hold

their

present pitch setting......The standard procedure would then be no

different

than any of the previous failures we've discussed.

However, for the sake of "illumination", I'm taking the liberty of

setting up

such a scenario....Ed you're right, there is a "Conning/Flexing"

phenomena

which occurs that is most prevalent at the Blade tips.....and ends

before the

Prop Hub, exactly where depends on the stiffness of the Blade.....The

stiffer

the Blade the further outboard, and the softer being further inboard.
Regardless, the LAEV's Hub merely sees this as a perpendicular Force on

the

Shank..........I agree with you, and it was previously discussed, that

two (2)

Bearings spaced apart on the Shank would be a stronger approach, but in

my

opinion way overkill.......The Bearing on the LAEV is quite capable of

taking a

great deal more perpendicular loading than it could ever be exposed to.

A

failure as shown in attachment NO 1 would take a TREMENDOUS amount of

force

which is well beyond the actual Blade design parameters and would be

considered

catastrophical.

Now for the kicker!!!!!.......The above is what's considered Static

Loading.

However in actual usage (Dynamic Loading), this becomes a completely

different

story since we gain an ally, Centrifugal Force.

Reffering to attachment NO 2:

A= 31,800 lbs.........Centrifugal Force at 3000 rpm (Dynamic Loading)
B=  1,459  " .........Perpendicular Loading at Blade mid point

(17.5"/1.612")

C= 15,839  " .........Load on Bearings (Static loading)

What this means is:
If you were to place Load B on the Blade, the Bearing will be loaded to

15,839#

at C static. As soon as you start to spin the Blade the dynamic loading

at C

will star to shift to the front of the Bearing, as the rpm increases

till you

get to 3000 rpm which unloads the perpendicular loading on the Shank to

0

(zero) lbs. This of course changes with Gyroscopic Forces......So you

might say

this prop is designed for 2918 lbs of thrust at zero Perpendicular Shank
Loading ;)

I hope most of you made sense of my babbling, especially you Mr. Test

Pilot:)

I'll be more than happy to clarify it further if necessary.

                                                            Butch

 Thanks, Butch for clarifying the situation.  Even my befuddled brain

understands.  That was the last thing I could think of, so sounds like all
bases are covered.

Ed

 
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