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Apr 30, 2007, 09:22 PM
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KF Park Jet....V3 videos, plans


Iv'e been intrigued with the KF airfoils and related discussions for a while now. I decided to build a park jet using the KF airfoil design.

Step 1: I'm building a full size glider without the fuse, electronics etc. just to get used to building this type of wing and to do some glide tests to find the cg and see what else I can learn.

This is the first time I've used fan fold. The stuff I have has film on one side. Seems like good material except it is very wavy.


The wing has a 36" span a 18" root chord and a 6" tip chord.

The KF step is at 50% chord and is about 1/2" deep. I formed the step by gluing a 3/4" wide strip of fan fold between the top and bottom surface near the step. After the glue dried I rounded the leading edges a bit and taped the upper and lower leading edges together.

Next I'm goaing to add fins and also add a boom out the front to add weight to balance the cg for the glide tests.

The overall goal is to see if I can make a good looking jet with good low speed characteristics. Top speed is not my objective with this one.
Last edited by leadfeather; Oct 22, 2008 at 07:41 AM. Reason: needed editing
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Apr 30, 2007, 11:27 PM
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Ready to glide


Fin added.

The boom is attached to the bottom of the wing with a couple of patches of velcro. If the glider noses in during glide tests, the boom is suppose to break away at the velcro.

The plan is to change cg by moving a weight along the length of the boom and find the useable cg range. I'm curious to see how far back the cg can get and still have a stable glide.
Apr 30, 2007, 11:41 PM
Victoria Super Mortem
UBILDIT's Avatar

Cool ...!


Looks like you're on the right track in a cool, technical, not going to damage your test subject while testing sort of way.. I dig it..
Are you going to make it EDF, Pusher, Tractor???

Bo
May 01, 2007, 05:57 AM
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leadfeather's Avatar
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Quote:
Originally Posted by UBILDIT
Looks like you're on the right track in a cool, technical, not going to damage your test subject while testing sort of way.. I dig it..
Are you going to make it EDF, Pusher, Tractor???

Bo
Thanks Bo! Making a glider version first to get the wing flying well is not really my original idea. I've seen it suggested in other forums before and I thought it was a very good idea. This test glider only has about 1 1/2 hours build time. A small investment really to help me put togheter a better final jet.

I'm thinking of making it a mid wing drive. For a jet, I think the pushers look the best; but with mid wing drive; the propeller can be better protected for landings and I can also have prop wash over the elevons to try to get the most out of the low speed handling.


The "jet" look I want to achieve is something like a Stryker or FunJet... "ish"
Last edited by leadfeather; May 01, 2007 at 06:12 AM.
May 01, 2007, 06:14 AM
gpw
gpw
“There’s no place like Foam”
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Pb , the only thing is you'll lose efficiency with the "prop in the slot "...we've tried alot of pits planes and then regular versions of the same plane (tractor and pusher) the pits planes were slower and more draggy ... True ...!!
to save props , use a propsaver and fly carefully ...especially near the ground ..
Pushers seldom break props...
elevons are not particularly effective at very low speeds , but a rudder is ..
Latest blog entry: Lost plans
May 01, 2007, 06:41 AM
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leadfeather's Avatar
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Quote:
Originally Posted by gpw
Pb , the only thing is you'll lose efficiency with the "prop in the slot "...we've tried alot of pits planes and then regular versions of the same plane (tractor and pusher) the pits planes were slower and more draggy ... True ...!!
to save props , use a propsaver and fly carefully ...especially near the ground ..
Pushers seldom break props...
elevons are not particularly effective at very low speeds , but a rudder is ..
gpw,

I am still debating the prop location decision. I have been impressed by the slow speed handling of some other wings with the "mid wing slot drive" and elevon controls. The SuperFly and the Slow Flying Object come to mind as good examples.

There is also an indoor pusher F-22 that uses tailerons and thrust vectoring that is amazingly agile at very low speeds.

If this turns out to be a nice wing, maybe several layouts can be tried and compared??
May 01, 2007, 06:51 AM
gpw
gpw
“There’s no place like Foam”
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I think the reason they fly so good indoors is because they are more draggy (and usually pretty LIGHT too)..maybe that's good for your application ..several layouts might be a good idea , just for comparison ...
The SF SFO and SuperFly , sure do fly well , but you'll notice the more adventurous will install a rudder for ultimate control ...Try it all out , it's FUN
Latest blog entry: Lost plans
May 01, 2007, 06:59 AM
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leadfeather's Avatar
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Check out this clip of the indoor F-22 pusher...amazing!


http://www.metacafe.com/watch/482969...aptor_extreme/
May 01, 2007, 07:04 AM
I'm not flying backwards!
Tony65x55's Avatar
Great project Lead. I have to echo Glen's comments regarding prop placement. It's a fairly high aspect ratio delta and you shouln't have too much problem balancing to CG with a pusher prop. The original KFm Wing (Similar, Higher AR, +sweep) has no issues regarding slow flight and I think your design will achieve your goals.

Smart way to check your CG. This is going to be a fun project.

Tony
May 01, 2007, 07:18 AM
gpw
gpw
“There’s no place like Foam”
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Whoa!!! that 22's TOO COOL ... and the pilot ain't half bad either... bet it's a feather...and a pusher too ...Wow!!!
Latest blog entry: Lost plans
May 01, 2007, 07:34 AM
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leadfeather's Avatar
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Quote:
Originally Posted by gpw
Whoa!!! that 22's TOO COOL ... and the pilot ain't half bad either... bet it's a feather...and a pusher too ...Wow!!!
Yep, it's a pusher, with thrust vectoring in both pitch and yaw!
May 01, 2007, 07:54 AM
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leadfeather's Avatar
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Glide test video


cg is now located. Wouldn't have dreamed of doing this with the real thing, in my front yard, and in these conditions!

cg is 8" back from nose of wing. I'm gonna play with this some more after work.

https://www.rcgroups.com/forums/show...08#post7374434
May 01, 2007, 12:49 PM
This looks really promising fromt the video demo.
May 01, 2007, 02:47 PM
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leadfeather's Avatar
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Quote:
Originally Posted by Tony65x55
Great project Lead. I have to echo Glen's comments regarding prop placement. It's a fairly high aspect ratio delta and you shouln't have too much problem balancing to CG with a pusher prop. The original KFm Wing (Similar, Higher AR, +sweep) has no issues regarding slow flight and I think your design will achieve your goals.

Smart way to check your CG. This is going to be a fun project.

Tony
I think you guys have got me convinced to go pusher. It makes the build a little simpler too.

Looking for ways to make it look cool without getting to complicated. Suggestions and especially sketches very welcome.
May 02, 2007, 07:55 AM
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Sketch


Here is a sketch of what I have in mind for the K F Park Jet.

The fusealage will have access hatches on top to get to the battery and electonics.

I'm still trying to decide where to put the elevon servos. I might put them outside the fuse, right behind the steps for ease of installation and convenient access.

I think I may have a little bit better way of building the wing with the KF step. I should be starting to build this evening.


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