|Aug 01, 2013, 10:34 AM|
Joined Feb 2007
For the general reader
I have ended the discussion with whiskykid.
The following comments are based on experimentation and observation.
1- Look at a prop that is at rest (not turning) with an eye in the plane of rotation. Yes you see the back of the prop blades due to their angle of attack.
2- Where would a blade go if detached for any reason while turning at thousands of rpm ? Prop blades have detached at high rpm particularly the props that have folding blades as often used on sailplanes.
Experimentation I made as follows _ _ _
Using a folding blade propeller I filed the material so that the blades stop allowed the blades to go forward a good 10 degrees ahead of the rotation plane. I wanted to see if the rotating blades at high rpm would form a cone with its apex toward the rear and the cone base forward of the hub attachment to the motor shaft due to the forward thrust of the blades.
The observed results are that the centrifugal force of the blades is so much stronger than the thrust that the blades are not forming an observable cone. The blades are turning in a pretty well flat plane and not forming an observable cone.
Conclusion _ _ _ a prop blade would fly out along the rotation plane BUT . . . . there is a "but" . . . . . considering that the mass of the blade had a forward thrust as it is detached it becomes unpredictable what trajectory it would take . . . . . considering also the speed at which the center of gravity of the detached mass would be moving, it becomes a very dangerous projectile.
Consider a small prop of 10 inches diameter and and the blade CG estimated at 4 inches from the rotation axis and assume a 12,000 rpm.
The CG (mass) of that blade would be travelling at 285.6 mph.
Much too fast for me to get out of the way if it is coming toward me .
Ya _ _ _ I will be in front of the prop only to start the engine at low rpm and move behind the plane of rotation for any higher rpm tests and will never run an engine in the pit areas.
Anyone can contradict on the basis that the risks are small but it is so easy to avoid another risk in our lives.
|Aug 02, 2013, 01:06 AM|
At least if you are hit by a breaking prop its your own doing so no one else is to blame. You are far more at risk in life from those imbeciles that insist on operating their mobile phones whilst driving. When caught they ought to be flogged!
|Sep 29, 2013, 07:40 PM|
Is anyone using the Evolution 20GX in this plane?
Just wondering how it compares to the DLE.
|Oct 15, 2013, 12:44 PM|
What spinner are you guys using?
Anyone with a DLE 20 running a tru turn spinner with a Xoar 17x6. Just wondering if I need a special cut. I have a message into try turn but haven't heard back yet.
I was looking at the H9 P51 spinner but I am not sure it can be adapted to the DLE20?
After looking around some more I see that the H9 spinner uses a standard 10-32 bolt. So maybe I can just get an adapter for it.
But I guess the question is would the Xoar prop fit in the H9 spinner?
|Oct 17, 2013, 11:43 PM|
Just a few picts of how I mounted my DLE 20RA on my Eagle. I broke in the motor today and should have it back on the plane soon. I am waiting for one more servo to show up and then I can maiden this thing!
|Oct 18, 2013, 12:19 AM|
as someone pointed out too me, you should consider putting some x bracing in that open area on top the motor box!
I see you hav some corner stock, but some more on top would help a lot!
|Oct 18, 2013, 10:31 AM|
I pinned my firewall and cut a piece of 1/8th ply to fit the top and the cut out all but about 3/4 inch which left the top open but really stiffened it up
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