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Gnat - I'm running out of props!

Old 01-16-2010, 01:31 PM
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Popriv
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Default Gnat - I'm running out of props!

any tricks to get the prop to stop horozontaly? no landing gear and I brake the prop almost every flight so far!

Tried tightening it against compresion but its not working.

steve
Old 01-16-2010, 01:46 PM
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Default RE: Gnat - I'm running out of props!

Tightening against the compression with the prop horizontal nomally works. What engine/size prop do you have and what kind of plane is it on?
Old 01-16-2010, 01:52 PM
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Default RE: Gnat - I'm running out of props!

clock the prop so that is stops sideways, hard to explan but its the free spinning area. also MAS props tend to be more flexable. APC props are more brittle
Old 01-16-2010, 02:08 PM
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Default RE: Gnat - I'm running out of props!

Training schools often use Graupner grey series props.
Old 01-16-2010, 04:18 PM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: j.duncker

Training schools often use Graupner grey series props.
The Graupner props are the only ones that I've ever seen that had a warning about keeping the prop hydrated.

The warning states something along the lines of, if the prop is left in a too dry environment the plastic will dry out and become brittle over time. They advise re-hydrating the props.

This threw me for a loop! I had never heard of anything like this and I'm still wondering about it.

I see no other manufacturer include anything like this in their documentation or warnings.

Any idea as to what this is all about?

Old 01-16-2010, 04:31 PM
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Default RE: Gnat - I'm running out of props!

The old nylon 'unbreakable' props use to carry a similar warning. After prolonged use they would go brittle and be prone to break. They could be revived by boiling in water.
Old 01-16-2010, 04:57 PM
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Default RE: Gnat - I'm running out of props!

I assume you are landing with the engine stopped and that you try to land as slow as possible without stalling. Just before touchdown, at what angle is the prop, as seen from the front like, when you start the engine? You are looking for it to be horizontal at that point. The wind will be trying to turn the prop in the same direction that it was running at, but engine compression should stop it in the horizontal position. You should be able to decide if the prop must be moved a little clockwise or a little counterclockwise. Just make a little sketch and figure it out yourself. Some people may have convinced you that this plane is easy to fly. It is cheap, but making a smooth landing with it may be very difficult, since the plane does not have a conventional air foil. I probably would be breaking props on it, and I have SPADS in which I have never broken a prop in say 5 years. Occasionally I have discarded a prop because it had dug into the dirt hundreds of times and had a lot of small nicks in the tip. My SPAD Bi-Plane, as an example, will slow down to a stall and then gently kiss the ground because it will fly all of the way. In two years it has never made a bad landing and never broken a prop. The Gnat simply stops flying and drops, and the point at which it does this is hard to determine. Others will contradict me 100%. You decide.
Old 01-16-2010, 05:37 PM
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Default RE: Gnat - I'm running out of props!

villa's right on that, they dont float. I forgot to mention that having the engine stopped is madatory also, villas the man!
Old 01-17-2010, 12:20 AM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: Popriv

any tricks to get the prop to stop horozontaly? no landing gear and I brake the prop almost every flight so far!

Tried tightening it against compresion but its not working.

steve
are you flying wood props, or plastic/nylon if your flying wood, then stop, then try master airscrew props until you can land without a prop strike, the MAS props can take a beating and will last for a while then after you have mastered landing without stopping the engine on the prop, swithch to wood or fiberfill props like APC, the APC will snap off as well if you hit the ground hard enough with them.

its hard to garentee that the prop will stop on the compression stroke if you kill the engine, it helps but not all the time
Old 01-17-2010, 01:30 AM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: opjose


ORIGINAL: j.duncker

Training schools often use Graupner grey series props.
The Graupner props are the only ones that I've ever seen that had a warning about keeping the prop hydrated.

The warning states something along the lines of, if the prop is left in a too dry environment the plastic will dry out and become brittle over time. They advise re-hydrating the props.

This threw me for a loop! I had never heard of anything like this and I'm still wondering about it.

I see no other manufacturer include anything like this in their documentation or warnings.

Any idea as to what this is all about?

I had one (15-8 3 blade) that threw a blade in flight and caused the plane to crash. Maybe there is something in that warning?
Old 01-17-2010, 02:33 AM
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Default RE: Gnat - I'm running out of props!

take the prop/spinner/nut/ect off the engine, then turn the engine shaft by hand (counter clock wise) till you can turn it (with just 2 fingers). put the prop horz to ground then tighten. when the engine dies it will stop in that spot
Old 01-17-2010, 10:07 AM
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Default RE: Gnat - I'm running out of props!

Hi RVman
The prop falling off does not mean an automatic crash. If the prop had a weighted prop nut things would be more interesting. One of out fellows had the 60 size engine fall off the plane. While he had much experienced, it was thought he would not make it, and he clearly yelled for help. He had good altitude. One of our old timers ran over (hobbled over as best he could) and he talked him into a safe landing. Keeping the pilot calm was the main thing. Had to come in and hold a LOT of down elevator, modulating it carefully as needed. A perfect landing. The engine was found and was not damaged.
Old 01-18-2010, 08:59 AM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: Villa

I assume you are landing with the engine stopped and that you try to land as slow as possible without stalling. Just before touchdown, at what angle is the prop, as seen from the front like, when you start the engine? You are looking for it to be horizontal at that point. The wind will be trying to turn the prop in the same direction that it was running at, but engine compression should stop it in the horizontal position. You should be able to decide if the prop must be moved a little clockwise or a little counterclockwise. Just make a little sketch and figure it out yourself. Some people may have convinced you that this plane is easy to fly. It is cheap, but making a smooth landing with it may be very difficult, since the plane does not have a conventional air foil. I probably would be breaking props on it, and I have SPADS in which I have never broken a prop in say 5 years. Occasionally I have discarded a prop because it had dug into the dirt hundreds of times and had a lot of small nicks in the tip. My SPAD Bi-Plane, as an example, will slow down to a stall and then gently kiss the ground because it will fly all of the way. In two years it has never made a bad landing and never broken a prop. The Gnat simply stops flying and drops, and the point at which it does this is hard to determine. Others will contradict me 100%. You decide.

OK, as I suspected it has allot to do with being a gnat. I've had 5 flights, two of them I was able to trim it out and fly 7-8 min. this is not an easy to fly plane very pitch sensitive but fun. I did try to set the prop horizontal as it hit compression. Its an OS .15LA. on the bench the prop would stop and bounce back. I wasnt thinking bout the air flow while flying may keep it pushed against compression??? Not much chance to flare this plane at touchdown. Like Villa said, it just stops flying and drops..
Sooo, I guess my question is this. I'm looking at building a battle axe type of plane. ( 1st attempt at foam wing cutting next weekend) I'm hoping that with a real wing ? I'll be able to put this plane down without landing gear? without breaking the prop ?

I killed the gnat yesterday! Last flight of the day (haha) I had the elevator on high rates. New that was a mistake as soon as it left my hand. to busy trying to fly I couldnt reach for the duel rate switch! Dropping the throttle would have helped, in hindsight. but it got all the way to the other side of the sand pits and planted nose first into the wet sand. Bent the aluminum U channel at a 90 degrees. mounted the engine on a stand, flushed with fuel to clean out any sand and it started right up. I'll build another gnat with improvements but now I'm moving onto cutting a foam wing . see how that flys. gotta be better than a gnat!

Steve
Old 01-18-2010, 09:41 AM
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Default RE: Gnat - I'm running out of props!

they will be worlds apart. the gnat is a cool and fun plane but it is more of a 3d type of plane. if you look at the QHORS and spad3, they are basicly the same. a nice and basic 3d trainer, great for learning 3D, the axe is for a totaly differnt flying. have fun!
Old 01-20-2010, 11:00 AM
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Default RE: Gnat - I'm running out of props!

usea reliable prop adapter or spinner. Axi prop adapter is a good choose.

http://www.rcecho.com/axi-model-rms4...mount-set.html


http://www.rcecho.com/prop-adapter/
Old 01-20-2010, 12:22 PM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: Villa

Hi RVman
The prop falling off does not mean an automatic crash. If the prop had a weighted prop nut things would be more interesting. One of out fellows had the 60 size engine fall off the plane. While he had much experienced, it was thought he would not make it, and he clearly yelled for help. He had good altitude. One of our old timers ran over (hobbled over as best he could) and he talked him into a safe landing. Keeping the pilot calm was the main thing. Had to come in and hold a LOT of down elevator, modulating it carefully as needed. A perfect landing. The engine was found and was not damaged.
Ok, i'll explain, I lost one blade of the three blade prop. The prop did not fall off. The vibration ripped the whole nose of the plane off, firewall forward. I lost over 2 lbs of weight and it was completely unflyable in that condition.
Old 01-20-2010, 01:47 PM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: flyoldman

use a reliable prop adapter or spinner. Axi prop adapter is a good choose. [img][/img]
[img][/img]
http://www.rcecho.com/axi-model-rms4...mount-set.html

[img][/img]
http://www.rcecho.com/prop-adapter/
I thought something like this would be just for electrics?

This wouldnt work for glow?
Old 01-20-2010, 02:43 PM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: flyoldman

use a reliable prop adapter or spinner. Axi prop adapter is a good choose. [img][/img]
[img][/img]
http://www.rcecho.com/axi-model-rms4...mount-set.html

[img][/img]
http://www.rcecho.com/prop-adapter/
WARNING DO NOT USE ANY OF THE ABOVE ON AN IC ENGINE.

Old 01-20-2010, 02:47 PM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: RVman


ORIGINAL: opjose


ORIGINAL: j.duncker

Training schools often use Graupner grey series props.
The Graupner props are the only ones that I've ever seen that had a warning about keeping the prop hydrated.

The warning states something along the lines of, if the prop is left in a too dry environment the plastic will dry out and become brittle over time. They advise re-hydrating the props.

This threw me for a loop! I had never heard of anything like this and I'm still wondering about it.

I see no other manufacturer include anything like this in their documentation or warnings.

Any idea as to what this is all about?

I had one (15-8 3 blade) that threw a blade in flight and caused the plane to crash. Maybe there is something in that warning?
I did not know that Graupner still included that warning.

Yes, boiling them will reduce the chance of breakage. In the days when I flew U control diesel combat with Tornado 8x6 [ Bright yellow anybody else remember them?] if you got old stock that had been sitting in the shop for months this was essential if they were to survive a crash.
Old 01-20-2010, 03:05 PM
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Default RE: Gnat - I'm running out of props!


ORIGINAL: j.duncker


I did not know that Graupner still included that warning.

Yes, boiling them will reduce the chance of breakage. In the days when I flew U control diesel combat with Tornado 8x6 [ Bright yellow anybody else remember them?] if you got old stock that had been sitting in the shop for months this was essential if they were to survive a crash.
Yeah they still do.

So there is something to it after all.

Do you know if this is applicable to props from other manufacturers or strickly a Graupner thing?


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