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Pusher Park Jets For all pusher jets and jet-like models.

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Old 09-05-2011, 09:15 AM   #1
rdoubledog
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Default Enlarged Yardbird YB22 to twins?

Real quick, I love the yardbird YB22 and have many flights on it. The hobbyist in me had wanting to do a larger version that would pull an 8" prop at slower speed and allow for better slow speed manueverability.

Well, to make a long story short, first flights have been depressing. Here are the dimensions:
  • Increased the wingspan to 25.5" and the length by 2".
  • Changed the tail surfaces making them larger to handle slower speed.
  • Widened the rails between the prop to accommodate an 8" prop.
  • Overall weight came out to be 550grams (19 oz) with 3s 2200 battery.
  • Motors used have ranged from several 1050kv's and various pitch 8" props. The best is that of an 1100kv and 8x6 prop but it still takes more than half throttle to keep in the air with sluggish performance pulling 170w @ 14 amps.
My buddy was talking to me after watching the initial flights and suggested going with two smaller Gunther 2208/1800kvs and considering either a side by side or pusher puller with 6x4's. Bench tests show that they will pull 104 watts @ 10 amps each.

This seems to be more in line.

Just not sure what to experiement with next. The push/puller would be the easiest to setup but would be a little challenge for CG and wiring.

I'm thinking about doing up the side by side and modifying the rails as the servos and links would need to be relocated. Nothing a few hours can't accomodate.

Please advise and more pictures on the next post.
-Jamie









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Old 09-05-2011, 09:22 AM   #2
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PUSHER - PULLER vs SIDE BY SIDE?

Here are the other pics with side by side and the bottom showing how the rails have been modified from the orriginal version. They're a tad taller to accept the 3s 2200 battery.

Lastly, my final thoughts are to run the two Gunthers (2208/1800's) off of a single 3s 2200 battery to save weight. This will still provide decent flight times. I'm sure the sound of the twins purring along would be sweet.

Just wondering about a possible increase in performance. Not looking for highspeed flight, just a little more low speed manueverability and high alpha.


My final thoughts are to trim down the overall length starting with the nose, remove the KFM airfoil and put the rails at 7" to get back to a basic YB22 format, but with possibly leaving the twin setup. As it sits, the addition of an extra motor/prop/esc and wire harness would only add about 60 grams putting me upwards of 610g (21 oz).

Just wanted something a tad different and love experimenting. Its only foam and doesn't take long to get an idea from paper to reality.

Peace.

Ps, Max (John) told me today that wiring the two motors pulling 104 watts each should only pull about 175watts when wired to one battery. Man, I've got a lot to learn about electrics.







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Old 09-05-2011, 10:20 AM   #3
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I would say side by side

Need More Glue!!!
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Old 09-05-2011, 11:01 AM   #4
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Use the bigger motors side by side, that style of jet has a lot of drag to it and you need all the thrust you can get. better yet, use one 3648-1450kv motor , with a 7x6 apc prop on 5 cells

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Old 09-05-2011, 03:40 PM   #5
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Jamie,
I like the idea of side byside pusher better than the push pull. I haven't replaced a propellor on the YardBird in 4 years! I think the front prop would be much more succeptable to damage.

I dunno, that's just my $.02.

One more random thought bubbling to surface: The YB-F22 works best when it's LIGHT. Even on windy days it behaves better with the smaller batteries.

Can't wait to see the build develope!

Please call me John. I came up w/ Max2112 when I thought you were all internet predators after me Lucky Charms!!
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Old 09-05-2011, 07:19 PM   #6
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I've recently purchased two new Gunther 2208/12 @ 1800kv each. Ran them both on separate aircraft for a few flights and realized that their now exactly whats needed for a particular airframe.

Was hoping to use them on the project jet. Got them wired up running together on the bench just now and I noticed that one of them has a bad vibration with the 7x4. Changed props to a 6x5 and still did the same but not as noticable. Wiggled the prop shaft and see a little play in there.

Could the bearings be bad so quickly? My first thoughts are to trash it and just order two new ones. Any ideas?

Thanks for the feedback,
Jamie

Oh and the sound twins make is pure music-!
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Old 09-05-2011, 07:24 PM   #7
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@ Chellie, I've got a ton of 3s in various sizes. Goal is to use whats available before buying more batteries. With this project, I'm wanting a lot of slow high alpha vs outright speed. (there's a scratch built profile F18 that gives all I can handle in that area).
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Old 07-04-2012, 12:41 AM   #8
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Default Elevons . confused ?

Just flew my F22 for first time today. Destroyed in 2 seconds. I hate to admit it , Been flying RC for 50 years and right after a good launch ,it turned left ,so i gave right to correct ,and it turned harder left and was destroyed. Don't elevons work the same as ailerons? Right elevon should go UP for a right turn and left elevon should go DOWN. Am i going nuts or what? THE (OLDER) GRUMP
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Old 07-04-2012, 12:53 AM   #9
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IT WAS a YARDBIRD F22 by the way. I should stick to slower planes, so i have more time to react, I'm 81 now and eyes and the fact that i have to fly from a mobility scooter don't help. THE OLD GRUMP
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