| 05-17-2015 04:16 PM |
| Lazy Ace |
Re: Prop hub void - would you fill for 4-bolt drilling?
Quote:
Originally Posted by OLD PRAIRIE RED NECK
We will have to agree to disagree on this one. In my opinion "experienced pilot" and "didn't think to cut the throttle" don't belong in the same sentence.
Oxymoron.
Would you put in a police accident report that "I didn't think to take my foot off the gas peddle when I approached that congested intersection"?
Green driver, green pilot!
"Didn't have time?" I'd buy that!
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And people always tell the truth when giving statements involving traffic accidents 
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| 05-17-2015 03:55 PM |
| OLD PRAIRIE RED NECK |
Re: Prop hub void - would you fill for 4-bolt drilling?
We will have to agree to disagree on this one. In my opinion "experienced pilot" and "didn't think to cut the throttle" don't belong in the same sentence.
Oxymoron.
Would you put in a police accident report that "I didn't think to take my foot off the gas peddle when I approached that congested intersection"?
Green driver, green pilot!
"Didn't have time?" I'd buy that!
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| 05-17-2015 12:03 PM |
| Lazy Ace |
Re: Prop hub void - would you fill for 4-bolt drilling?
Quote:
Originally Posted by OLD PRAIRIE RED NECK
Dennis I am going to disagree strongly on this one!
Throttle management should be TAUGHT! Not left up to chance. That in my opinion is the single biggest down fall of most instructors. The very first lesson before a student is taken on the first flight is to teach them to develop that THROTTLE OFF reflex whenever things get out of hand! They shouldn't ever have to "think to reduce", it should be an automatic refex.
If they haven't learned that then you are a failure as an instructor!
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Everyone I know teaches throttle management and it works every time in practice when the student knows there is a safety net. Even experienced flyers have watched at one time or another in open mouth disbelief as their plane went in never touching the throttle. Good throttle management in emergency circumstances comes from years of experience its called reflex. You can teach it all you want but if its not reflex most likely it will be to late.
Chopping the throttle when in trouble isn't throttle management. Throttle management is not only keeping the aircraft within the flight envelope but within the capabilities of the pilot something that is as individual as there are pilots.
A good instructor teaches this but cannot guarantee the student will follow best practices once they have their wings.
Dennis
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| 05-17-2015 10:03 AM |
| OLD PRAIRIE RED NECK |
Re: Prop hub void - would you fill for 4-bolt drilling?
Quote:
Originally Posted by Lazy Ace
Throttle management comes with experience. How many time have you seen even experienced pilots ride their model into the ground not thinking to reduce the throttle.Dennis
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Dennis I am going to disagree strongly on this one!
Throttle management should be TAUGHT! Not left up to chance. That in my opinion is the single biggest down fall of most instructors. The very first lesson before a student is taken on the first flight is to teach them to develop that THROTTLE OFF reflex whenever things get out of hand! They shouldn't ever have to "think to reduce", it should be an automatic refex.
If they haven't learned that then you are a failure as an instructor!
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| 05-17-2015 09:02 AM |
| Lazy Ace |
Re: Prop hub void - would you fill for 4-bolt drilling?
Quote:
Originally Posted by OLD PRAIRIE RED NECK
Dennis, if you want to see discouragement try a beginner with a bent crankshaft from a strike with a nice strong prop.
On the "trainer is too fast" front, there are 3 things I find more effective than junk props.
1) Choosing a more suitable airframe. Just because it said "Trainer" on the box doesn't mean it is.
2) Correctly sizing the prop. Large diameter/low pitch = good climb, moderate speed and a braking effect on final.
3) Proper use of the throttle. Contrary to popular belief an engine does not have to run full bore whenever the plane is in the air.
Back to subject at hand...
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Most trainers (ARF) come with 3 bladed square tip prop to slow them down (lousy prop) works as intended to keep the speed down.
Low speed prop strikes very rarely bend crankshafts on 40/50 size motors. If a beginner is bending cranks he has other concerns that may discourage him.
Throttle management comes with experience. How many time have you seen even experienced pilots ride their model into the ground not thinking to reduce the throttle.
As instructors we work with what the student has on hand providing its not considered unsafe. I have even had students insist on using that crummy three bladed prop because its what is recommended by the manufacturer even though it might take a week or so to get a replacement. They don't think they should fly with a 2 blade prop. I can only suggest I'm not going to force anyone.
Dennis
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| 05-17-2015 06:29 AM |
| OLD PRAIRIE RED NECK |
Re: Prop hub void - would you fill for 4-bolt drilling?
Dennis, if you want to see discouragement try a beginner with a bent crankshaft from a strike with a nice strong prop.
On the "trainer is too fast" front, there are 3 things I find more effective than junk props.
1) Choosing a more suitable airframe. Just because it said "Trainer" on the box doesn't mean it is.
2) Correctly sizing the prop. Large diameter/low pitch = good climb, moderate speed and a braking effect on final.
3) Proper use of the throttle. Contrary to popular belief an engine does not have to run full bore whenever the plane is in the air.
Back to subject at hand...
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| 05-16-2015 05:33 PM |
| Lazy Ace |
Re: Prop hub void - would you fill for 4-bolt drilling?
Nothing wrong with nylon including Master Airscrew props in the right application. A beginner with a 40 size trainer who keeps nosing over and killing the engine during taxiing, take off and landing might loose interest if he has to change a prop or two every flight. Those Master Airscrews can take a few ground strikes and keep going and a second advantage is their inefficiency will slow the trainer down somewhat.
Dennis
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| 05-16-2015 02:59 PM |
| OLD PRAIRIE RED NECK |
Re: Prop hub void - would you fill for 4-bolt drilling?
Plastic Master Airscrew props are what you pay for - cheap, hard to balance and inefficient. I relegate any that accidently come my way to stir sticks and airboats.
I have never understood the attraction(other than scale looks)of bolt on props. Wouldn't center bolt set ups give a degree of engine damage protection in the case of a prop strike?
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| 05-16-2015 09:24 AM |
| reo |
Re: Prop hub void - would you fill for 4-bolt drilling?
Quote:
Originally Posted by Lazy Ace
Any prop of any size is designed to work safely at the RPM of a suitable motor to turn that prop providing the prop structural integrity has not been compromised. That Master Airscrew was designed for center mounting it doesn’t look to be enough material to drill for 4 mounting screws. Used as designed it will be safe. I don’t care for the larger Master Airscrew props because in the event of the prop striking the ground there is a greater chance of bending the crank because the Master Airscrew does not break as easy as a wood prop.
That being said there are better choices out there, much more efficient and with larger hubs to allow for multiple screw mounting patterns.
Center bolt/screw vs any given bolt pattern I think is mostly personal preference. I have had many single screw mount gas motors and properly tightened have never given me a problem. Brison even has a single screw mount on their 100cc twin and it gives no problem. No loctite needed. I have seen props come off from broken bolts in bolt pattern hubs. I think in most cases when a prop comes off the error is poor installation rather than a fault with the prop or mounting method.
Center hole props should be reamed not drilled. The rake and angle of the cutting edge and flutes of the drill tend to want to dig in or grab when the cut is started. Without a drill guide/bushing you will be very lucky to keep the drilled hole on center. With a reamer it’s designed to follow the existing hole and has a less severe rake angle on the cutting surfaces. Also the flutes are usually straight with less tendency to pull the tool into the wood.
Just my personal observations for what their worth.
Dennis Pratt
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I agree with Dennis as far the center bolt thing, my turbo-prop is center bolt only and I run a 20 X 12 CF three bladed prop....also no thread lock required considering direction of prop rotation.....ron
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| 05-15-2015 09:29 AM |
| grosbeak |
Re: Prop hub void - would you fill for 4-bolt drilling?
Quote:
Originally Posted by cf-drg
Just on the runout of the hub.. I feel they should have had 2 dial indicators. 1 on the adapter and one on the motors hub...The adapter is only going to be as good as the engines hub... I would have liked to see what it was like..
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Agreed - when I have time to get back into this problem I plan to measure the runout on the face of the adapter if possible.
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