"1/2 A" & "1/8 A" airplanes These are the small ones...more popular now than ever.

Building a 1/2a turbine, sort of, work with me on this

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Old 10-28-2013, 06:03 PM
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subarubrat
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Default Building a 1/2a turbine, sort of, work with me on this

So turbines don't have a 1/2a category but if they did the smallest one would be in the 1/2a group right? And we like older smaller models as 1/2a fans right? I think that this project is better suited to this group because of those reasons, and the turbine guys for the most part have no interest in something like this.

I picked up a .20 sized 1979 ducted fan Jetster 20 by Midwest and instead of the RK720 fan I am using a Kolibri which is the smallest production turbine, definitely the .049 of the turbine world. I have the plane and am just waiting on the turbine to arrive.

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Old 10-28-2013, 09:52 PM
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Wow..! It looks like a good match from here, keep us posted on it's progress.
How much fuel would it need to run for a few minutes at full throttle...?
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Old 10-28-2013, 10:27 PM
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It burns 65ml a min at full throttle. So 1 pint (16 0z) will run for 8 min at full throttle. They spec the engine, ECU, pump, and 1 pint of fuel as weighing 1.6lbs. I may go with a 14oz tank based on my guess of throttle use, that should give me about a 10 min nominal flight time.

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Old 10-31-2013, 08:30 AM
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That sounds like a hoot. Good test platform to get the gist of the turbine operation and characteristics. Good luck and keep us posted. What was the turbine system cost?
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Old 10-31-2013, 09:52 AM
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I have a Jetser its a great flying plane! I have been flying it with a K&B 45 and Turbax setup. Its moves along pretty good maybe 80 mph range. I get about 8 lbs of thrust from my setup.
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Old 10-31-2013, 09:56 AM
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Old 10-31-2013, 11:14 AM
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Very cool, I love this sort of stuff! Does the plane need any [much] elevator trim to fly level..?
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Old 10-31-2013, 11:38 AM
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No, it flew pretty much straight and tru. I thought the high thrust line it would require a ton of up trim. In this picture, the fuel tank is in the nose, which created fuel delivery problems. Later I moved the tank behind the fan. I have thought about mounting a Dynamax and OS 91. Can't wait to see it done, Good luck!!!
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Old 11-02-2013, 05:44 PM
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Your flying a Jetster 20 with a .45 fan? Fan no too heavy? Not over powered? That would be good to hear, I test ran the Kolibri tonight and wow does it sound mean and is every bit of 5.5 Lbs thrust. Almost seemed a bit much for the Jetster but it weighs less than the the .25 powerplant and 5.5 Lbs is less than the 8 that your turbax unit would make. I should start gluing balsa this week.
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Old 11-05-2013, 03:22 AM
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The 45 is not too heavy for the plane, I have thought about bolting a OS .91 and dynamax on it. If your turbine weights less than the .25 and makes more thrust then I think you have a winner. I cannot wait to hear your flight report. Let me know if you want to sell the .25 you got with the kit.

Good Luck
-Jason
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Old 11-05-2013, 04:42 AM
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Wow, that looks good for me then, should have much better than a 1:1 thrust ratio yet still slow up much better than with the original. I picked out a very light flight pack and am building as light as I can.
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Old 11-06-2013, 04:28 AM
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Weighed my engine, ECU, tank, etc. last night and it comes in at 17.5oz , and my retracts arrived. I should have the fuselage framed up this week. The retracts are actually kind of nice, I had some concerns with them coming from China and the description being somewhat lacking. However they are built with decent materials and have good geometry, the weight penalty is fairly minimal and it will be a cool feature. They are about an inch taller than the stock design but not enough to worry about modifying them, and keeping the turbine that much higher to prevent FOD is not a bad thing.

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Old 11-06-2013, 05:10 PM
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That engine would be cool in an old House of Balsa F86.
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Old 11-06-2013, 06:44 PM
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Certainly an interesting exercise.
Bit out of time though, Mr Peabody set the Wayback machine to get that?
What does that 5.5 lbs thrust cost in real $$??
I ask as one can reasonably obtain that level of thrust with a ~$200 edf .( motor edf and esc) setup + batteries, arguably another ~$100 for 'good' ones.
Sans Papal Dispensation from the AMA to fly the thing :-)
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Old 11-07-2013, 07:40 AM
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A big reason is "because I can" but mostly because I enjoy the chance to go back and build the models I always wished I had built, And since the technology has come around to allow them to be built better, why not?
The turbine sells for $3500 new and I picked one up for less in the marketplace but it is a real gem, sure I could do it for $250 and I do enjoy EDF but this is a turbine! Because I can, and I have done EDF since 1996.
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