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Old Nov 06, 2012, 04:37 AM
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whats its glide like ..power off..mine with a forward COG just takes a nose dive.. only with the COG right back does it do an ok hands off flattish glide...

wonder why Ive got the odd results? all my thrust is at Zero.. power up and it doesn't climb, its just a flat and level acceleration
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Old Nov 06, 2012, 09:15 PM
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Aurora, Ontario, Canada
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I spotted the posts for the Regal Bipe.

The juices started to flow and I started thinking Hiperbipe. I've got the plans from FM which were for a bult up wing and fuselage. Thumbing my way through this thread and I'm now thinking that a Hiperbipe rendition is possible with a bit of bashing. Failing that, I'll build from the plans but do the wings using half-inch foam KFm wings.

http://images.rcuniverse.com/forum/u...26/Pi16175.jpg
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Old Nov 07, 2012, 03:34 AM
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That design will make for a good conversion to foam and KF..the originals wings are symetrical in section so a KFm4 wing is what will work best..
I tend to use more thinner foam layers for the wing, and build them up to get to the originals thickness..
Depending on what this original thickness was, you might get restricted to a KFm2 section by using the 1/2 inch foam as obviously in a KFm4 it will give you a 1.5" thick wing..
I did a quick sketchup measurement and the original has wings that are only 1" thick..

An alternative constuct that might be better is a KFm4 using 3x6mm layers with spars of 1x 1/8 balsa at the steps..that getting much closer to the originals wing thickness
A second alternative could use a KFm2 top step for the top wing and a KFm1 bottom step for the bottom wing (or even vice versa)
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Old Nov 07, 2012, 02:51 PM
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Thomas B.'s Avatar
Germany, Nordrhein-Westfalen, Cologne
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Quote:
Originally Posted by davereap View Post
whats its glide like ..power off..mine with a forward COG just takes a nose dive.. only with the COG right back does it do an ok hands off flattish glide...

wonder why Ive got the odd results? all my thrust is at Zero.. power up and it doesn't climb, its just a flat and level acceleration
Both Radius are quite neutral - especially the Kfm 4 wing has no trim changes between slow and fast flight, but I will check the glide again.
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Old Nov 08, 2012, 06:18 AM
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Dickeroo's Avatar
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Trond has done it again.

Here is a very stable platform, the KFm4 FPV, showing the beauty of Norway at sunset. A really spectacular video, in my opinion.

FPV49 v3 New Prop & Motor (7 min 13 sec)
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Old Nov 08, 2012, 07:51 AM
What could possibly go wrong?
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Stunning!
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Old Nov 09, 2012, 11:57 AM
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Great video!

Dave, I tried the glide of the radius 275: it remains level as long as the speed is high, when it slows down it goes into a shallow dive.
I moved then back the cog to 115 mm - it was more agile at slower speed, but I had to add a bit down trim for high speed and it was less exact on elevator; so I think the optimal cog depends on the desired flight style and flying speed.
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Old Nov 09, 2012, 12:03 PM
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Amazor!!!
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Old Nov 10, 2012, 04:57 AM
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weird cog results... I cant suss out whats going on... mine with your forward COG will go into a steep dive with power off, it needs the power up's prop wash to keep its nose up, or a lot more speed..and yet it flies lovely with the COG back on the step line at the root.. thats at 125mm back from its leading edge.

where did you put your steps exactly? the arcs on my two steps go exactly through that 125mm COG spot.. which is a 50% location on the main part of the wing, but ignoring the tail areas..might that be the reason?... and you didn't put any dimensions on your drawings..

At the end of the day it doesnt really matter as long as it flies how you like it to..but I am puzzled

Ive found another model that appeals... http://www.rcgroups.com/forums/showthread.php?t=1696964
Its been KF'd already, but with winter on its way I might just build one KFm4 style
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Old Nov 10, 2012, 05:11 AM
Reap the wild wind
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Bristol,UK
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And Thomas is using a much heavier motor and lipo combination so, unless his lipo is well back, I'd expect him to be nose heavy compared with you.
Just got the horns & control rods to install and sort out lipo access as I'm using a underslung fuse like Thomas. Pictures to follow once she's ready to go. Hope to maiden tomorrow so will post vid if all goes according to plan
Andy
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Old Nov 10, 2012, 05:19 AM
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I think going heavier just makes for a faster flying model.. its COG should stay much the same, although some personal choice on where you put the COG to get it flying how you prefer will let it vary..at least a bit..
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Old Nov 10, 2012, 06:30 AM
When pigs fly rc
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You wil love the mako Dave! Its a great flyer.
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Old Nov 10, 2012, 08:11 AM
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The steps of the radius 275 are at 160mm, which is 50 % of chord incl. ailerons. On your radius 250 the step is at 50% of chord excl. ailerons. And your step line is more curved. Maybe here is a reason for different cog location.
I put some dimensions to my sketch:
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Old Nov 10, 2012, 11:24 AM
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Second that love the Mako. Built mine with a KFM4.
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Old Nov 10, 2012, 02:02 PM
Reap the wild wind
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Bristol,UK
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Another Radius

Finished my KFm-4 Radius. 6mm depron with 3mm steps. Wingspan 495mm and total length 495mm including elevator. Motor is the MicroDan 2505 2535kv motor. I will maiden on 3S which should give me 19900rpm, 10.7V, 25A, 25oz thrust on a 6x4 prop. ESC is 40 amp mounted externally for better cooling. Will use a Turnigy nano-tech 1300mAh 3S 45~90C so shouldn't be pushed too much on the proposed set up. Ready to fly weight is 409 grams so I expect she will get a move on
Will maiden at 110mm back from le and see how she goes
Andy
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