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Aug 14, 2012, 05:16 PM
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So I managed to get some flight time this evening on the repaired Oshkosh. With the new reinforced wing and correct down-right thrust on the motor, the plane was a dream to fly.

My previous attempts on flying not only this but other "bigger than hobbyzone champ" planes have all ended after max 1 minute. I am a new rc pilot after all.

But this evening...oh my god. It was almost a religious moment. I finally understood what everybody is talking about when they describe a maiden flight where the plane almost flies itself.

First take off was magnificent. I powered up slowly, and the plane did a really long nice take off. It delicately lifted its tail and ran on the wheels a few yards, before I gently nudged the elevator and it ascended increadibly smoothly. No trimming, no nothing and it flew straight as an arrow. I just love this plane.

Once I got some altitude I flew around at 30-50% power. When shut of it glided great and the landings where very easy. One landing I'm proud of myself is when I came on the final leg straight towards myself, the plane gently touched down and stopped literally less than 1 foot from me.

An incredible experience. This one is for you Ken, with a BIG thank you!
An evening flight.
( Had some fun with iMovie. )
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Aug 14, 2012, 10:11 PM
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maurice076's Avatar
Thats some Nice stuff there man very cool!
Aug 14, 2012, 10:21 PM
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Quote:
Originally Posted by kronblom
What confuses me is that the CG doesn't seem to stay put. With that I mean that some dicussions I've seen says to move the CG depending on modifications etc. Have I got it wrong? Should I just work with the CG at around 2.6'' from the LE?
You're having trouble, because people are confusing the actual Center of Gravity and the desirable "design" Center of Gravity. When you get ready to fly, you should try to adjust the various bits or any additional weight to make the actual CoG and the desirable CoG coincide. All objects balance on their center of gravity, but that may not be where you want the balance to be when your plane flies right.

First you find the actual center of gravity by supporting the plane on a suitable stand. You try to get the fuselage level when you do this. If the balance point isn't where you want it, you shift the battery or add weight and try again. Once the balance point is where recommendations say it should be, you can go fly.

I build free flight planes and do this whenever I build. Make yourself a stand with two rods glued into a board. Put some padding, like rubber tubing, on the ends of the rods.

Joe
Aug 15, 2012, 07:38 AM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
Quote:
Originally Posted by kronblom
...
An incredible experience. This one is for you Ken, with a BIG thank you!
An evening flight.
( Had some fun with iMovie. )
Awesome! Thanks KB, that was quite dramatic. Love it!

Ken
Aug 15, 2012, 10:06 AM
Registered User
Glad you liked it. I was about to make some video when I found the trailer templates. :-)

There is a place in there where I almost hit a light post. Didn't notice that close call until I saw the video myself.

//KB
Aug 15, 2012, 12:40 PM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
KB,
The lightpost shot was one of the more dramatic, as well as the spinning to the earth one.

Ken
Aug 15, 2012, 07:58 PM
Registered User

Updated recommendation for Motor/ESC


Hi,

Looking forward to building my first Oshkosh Special.

I notice the links on page one to motor and ESC are out of date (specifically the parts are out of stock and have been for a while).

Anyone have a recommendation for motor and ESC from Hobby King?

For what it's worth, I believe that this one from BP hobbies fits spec:
http://www.bphobbies.com/view.asp?id...7&pid=B1898552

Thanks.
Last edited by RC Simon; Aug 15, 2012 at 08:10 PM.
Aug 16, 2012, 08:05 AM
Ken's CAD Models
dz1sfb's Avatar
Thread OP
RC,

That motor is the correct spec fo this plane.

Best wishes,
Ken
Aug 22, 2012, 03:14 PM
Registered User
Had the maiden with my 40 yesterday!

this plane is so easy to fly its hard to believe both of my landings were good too (a rare thing). It is even a forgiving design on components. I say this since i deviated a bit from the plans.

CF in wing picture
http://www.flickr.com/photos/5308189...in/photostream

Oshkosh picture
http://www.flickr.com/photos/5308189...n/photostream/

I used 6mm depron and went monoblockless. I also used flat carbon fiber (6mmx1mm) glued to the proper dihedral on the leading edges of the wing instead of dowels. I glued a strip of foam on the front edge of the carbon then shaped and taped (pic). I was going to do the dowel method but the pieces i picked were a bit warped.the wing is super ridgid i did 5 loops in a row to make my 6 year old happy.

i used a 24g 1700kv with 9x4.7. I went with a 1000mah 3S for the maiden since it seemed to balance better than my 2S with my fuselage design. Next time ill try 2S or switch out for the 24g 1300kV i ordered to run the 3s.

thanks again for the plans
Aug 26, 2012, 11:18 AM
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Wilfor's Avatar
Your plane turned out great flappy
Aug 26, 2012, 05:31 PM
Ken's CAD Models
dz1sfb's Avatar
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Quote:
Originally Posted by Wilfor
Your plane turned out great flappy
Ditto Flappy! Very clean build, and congratulations on the successful maiden flight.

I still enjoy flying these,
Ken
Sep 09, 2012, 10:37 AM
Registered User
thanks guys, i am very happy with this build...

Ive was flying today after a few more modifications.

I swapped out to a larger motor 39 gram FC 28-12 (only 6 bucks from HK) and a 1300maH 3S nanotech. Ran with a 7x5. I added a bit of strapping tape to the main and tail wings since i anticipated higher speeds. AUW now just under 15oz.

There was a lot more wind than i expected but with the extra power and weight it was fun
flying. I even got it up nice and high and shut the motor down for some gliding into the wind. Well i dont know if its gliding if your not making forward progress pretty much floating in place but it was pretty cool.

this plane is a confidence builder after my first scratchbuilt, a combat with only ailerons and elevator.
Sep 10, 2012, 12:03 AM
Yeah, that looks about right..
Has anyone scaled this down to say a wingspan of around 500-600mm?

I'm looking for a design for indoor/micro flying that isnt just simply a sheet of foam something more, well the difficulty of this build.
Thanks Cameron
Sep 10, 2012, 07:20 AM
AKA Don
Plans are available for 20, 30 and 40" WS models. See post 1 of this thread.

20" is 508 mm
Dec 06, 2012, 02:53 PM
Registered User

Electronics


I have just assembled a 42" Oshkosh Special with a KFm3 wing. It weigths 150g.
Now it is time to select the electronics, and I would like to give it a little more flight time. I also thought about using 3S so that Amps through the (cheap) ESC and conductors are reduced

Any advice on the motor, battery and prop to use?
By my calculations, I would need a Lipo 3S 1300mA (<120g) , a 1200KV Outrunner (~40g), and 9x4.5 props, for a AUW <320g.

Would this setup provide more flight time than the original, without sacrificing its behavior?


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