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Author Topic: Gizmo Geezer Reviews  (Read 11999 times)
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ScienceGuy
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« on: October 14, 2016, 09:37:52 AM »

I wrote two blog posts about the Gizmo Geezer propeller system. In the first one I created a test stand to run it on so I could better observe the operation. For the second blog post I installed the Gizmo in a NJAPF p30 model I have been flying for sometime.  By no means am I an expert in free flight so the comments are those of a relative beginner.

http://scienceguyorg.blogspot.com/2016/10/flying-with-gizmo-geezer.html   Flying With Gizmo Geezer

http://scienceguyorg.blogspot.com/2016/09/gizmo-geezer-review-part-1.html   Gizmo on the Stand

Bill Kuhl
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ricardo
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« Reply #1 on: October 14, 2016, 04:26:34 PM »

In the 'Gizmo on a stand' video ..

It seems to reverse just before the freewheel disengages.  You can see the clevis stop and then go backwards.

The prop slows down when this happens but its not clear if it follows the clevis into reverse.

Does this really happen?
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calgoddard
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« Reply #2 on: October 14, 2016, 06:58:37 PM »

Bill -

I have quite a bit of experience with the GizmoGeezer (GG) prop assemlby over the past several years and I really like it.

I use it in rubber scale models, non-scale models like the Flying Aces Moth and P-30.

Thanks for your tutorial.  It will help others understand the operation of the GG prop assembly.

I think the reverse action in the video may be due to the timing of the video frames.  The prop doesn't really reverse.  The GG looks like it is operating normally to me in that video.

When the tension on the wound rubber motor drops sufficiently, a tiny coil spring moves the drive dog forward allowing the prop to free wheel.  This retains a nominal number of turns, e.g. 30 - 50, so that the rubber motor does not bunch. CG shifting in your airplane is avoided which would otherwise adversely affect the glide of your model.  So with the GG you no longer have to braid your rubber motors. The GG with the spinner doesn't use a drive dog, but relies on slots in the spinner to engage and drive the prop.  The spinner moves forward and disengages from the prop when the motor run is nearly complete and there are only the nominal number of turns remaining in the rubber motor.

The accident you described is easily avoidable.  Thread a small length of fine gauge un-insulated wire through the hollow clevis pin and tie the ends snugly around the clevis sleeve. Cut off any excess.

The winding attachment locks into the front end of the clevis sleeve with a one-quarter clockwise turn.  The winding attachment will not come out of the clevis sleeve when locked in this fashion as the torque of the wound motor forces it to stay in its locked position.

Orv Olm recently switched to a new propeller supplier but I am happy with the replacement.  It is the equivalent of the old silver 9 1/2 inch re-pitched GG props.

Tie a piece of brightly colored ribbon (1/8 inch wide and four inches long) around the winding attachment and let the two ends of the ribbon extend loosely on each side.  When you drop the winding attachment on the ground or grass, it will make it a lot easier to find.

Make sure your blast tube has an inside diameter large enough so that the GG clevis sleeve can freely slide through the tube with the clevis pin inserted.

Here is another piece of advice.  On the nose bock of many scale models you will need to hog out a conical shaped segment of the bore extending rearwardly of the bore that supports the triple ribbed GG bearing housing. Otherwise the clevis sleeve or other parts of the GG prop assembly will bind when you adjust the Allen screws to provide, for example, 5 degrees of down thrust.    

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« Last Edit: October 14, 2016, 07:48:53 PM by calgoddard » Logged
Oldtime Flyer
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« Reply #3 on: October 27, 2016, 08:40:47 AM »

Who cares about gizmo, we could re pitch our own prop if necessary. this free wheeling unit is great but not a necessary.
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applehoney
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« Reply #4 on: October 27, 2016, 10:01:30 AM »

Sure you could repitch your own prop but it would not be commercially available as such ... so not legal for the P30 class
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tom arnold
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« Reply #5 on: October 27, 2016, 10:12:51 AM »

Of course the GG is not necessary. You can always make your own adjustable, freewheeling, tensioning, reliable, compact, and p-30 legal (if desired) unit for each airplane you fly. I wish you good luck and smooth sailing on the manufacture of the device. I have found that the successful fabrication to be the biggest pain in the rear of all the challenges we face in the shop. To me, the biggest advantage of the GG is the tensioning aspect and the elimination of having to braid motor after motor in the field (I fly scale). The GG is a luxury and I need all the luxuries I can get at my age.
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ScienceGuy
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« Reply #6 on: October 27, 2016, 10:13:39 AM »

George Bredehoft (Volare) told me that many people buy just the nose button to get the thrust adjustment feature. For me the features are worth it; it holds nose on, do not need to braid motor, do not need to create freewheel device, and thrust adjustments.

Bill Kuhl
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Mike Thomas
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« Reply #7 on: October 27, 2016, 07:47:26 PM »

Another very useful attribute of the Gizmo Geezer is that, after winding, the prop shaft is locked, so that you don't have to hold on to the prop until you are ready to launch. When you are ready to launch, you pull the prop forward on the shaft, put a couple of extra winds on (this disengages the lock), and away she goes.
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« Reply #8 on: October 27, 2016, 07:54:17 PM »

The GG is a great value; one of the great values in our hobby, IMO.  It does what it is designed to do, and does it very well.  It is light, adjustable, easy to use, and the prop (prior generations of which I have knowledge) was better than the unmodified Peck. 

Bill's review of the GG is very good, also.
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« Reply #9 on: October 28, 2016, 08:19:24 AM »

I've used the Gizmo with great satisfaction for P-30's and similar models. Reliable, does a fantastic job, etc. Can you build something that does the same thing? Sure, but you're not going to improve on it unless your goal is building something that will take more rubber. The screw adjustable thrustline feature is worth the money all by itself.
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Mmitch2782
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« Reply #10 on: April 14, 2017, 04:06:01 PM »

i built my own with a long dog for a scale spinner. 
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