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Old Mar 09, 2009, 12:28 PM
X-15 Jockey
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Joined Oct 2006
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Profile X-2 rocketplane

I started this over the weekend, watched "toward the unknown" again and was reading my X-planes book, got me into it 39" long, 33" wingspan. This plane had actually a pretty large wing, and the placement and sweep is such that CG shouldn't be too hard. I'm setting it up for rocket boost or electric pusher.

Here are the raw fuse/wing pieces taped together for a first look.

Frank
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Old Mar 10, 2009, 12:24 AM
Vacuum Tubes Forever BCT2/BCR3
MN AZ
Joined Oct 2006
115 Posts
Hello Frank,

I have a smaller prototype flying, 36" length and 28" wing span. Stability seem be quite good.
Motor is a 2408-21 / BP21 with an 8x4 prop and 1320 lipo. No scale in AZ, weight? Sorry for the bad pictures, cable for good camera is in MN and I am currently in AZ.

I have always been impressed by your profile designs and decide to copy you style.

JohnB

PS - the first drawing is the wing mac and the second is the elev mac
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Old Mar 10, 2009, 01:22 PM
X-15 Jockey
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Joined Oct 2006
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Cool, did you start this before I posted? If so, we are on the same wavelength Looks good, I have my elevator pivot point about where the elevator MAC hits the leading edge, I like about 25% area in front of the pivot and 75% behind. Are you using about 30% MAC for your CG?

Thanks for posting!

Frank
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Old Mar 10, 2009, 11:43 PM
Vacuum Tubes Forever BCT2/BCR3
MN AZ
Joined Oct 2006
115 Posts
I started designing the X2 and a B47 about a month ago. The X2 has been flying for about 3 week. Had problem with wing flutter at WOT and had to tape the leading edge of the wing. Will change out dowel for carbon when I build a new wing. I think I setup CG and pivot at 25% of MAC cord. Wing cord at fuse is 9 1/2 inches, CG is 7 inches back from leading edge. Elevator cord at fuse is 4 1/4 inches and pivot is 3 inches back from leading edge. I think both position are conservative.

I am current waiting for some carbon fibre so I can continue testing and building.
My carbon fibre order got mistakingly shipped to MN instead of AZ. @#$%^&* !!!

The image is my next project.

JohnB
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Old Mar 10, 2009, 11:56 PM
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Scottsdale, Arizona
Joined Jun 2006
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Holy COW these things are killer! This just might get me back into profiles.

Or I may have to build a full-fuse X-2

Barrett
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Old Mar 11, 2009, 02:04 AM
X-15 Jockey
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Joined Oct 2006
2,443 Posts
Excellent, I've been thinking about a B-47 for a while, but I was concerned about the long skinny wings, I'm anxious to see how you do with it, It isn't modeled very much. for wing stiffness, you could also laminate another layer of depron on the leading edge bottom front 40% and make it a KF airfoil. I did that with my F-117 when it was a bit floppy.

Frank
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Old Mar 11, 2009, 02:09 AM
X-15 Jockey
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Joined Oct 2006
2,443 Posts
Detailing finished...

here she is put together and detailed. Still need to do some glide testing and install servos and rx. AUW so far is 7 oz. Wing seems just a bit more flexy than I wanted, we'll see how it works when loaded.

Enjoy.

Frank
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Old Mar 11, 2009, 06:37 AM
Vacuum Tubes Forever BCT2/BCR3
MN AZ
Joined Oct 2006
115 Posts
The X-2 looks GREAT !!! Have fun with the first of many flights.

JohnB
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Old Mar 11, 2009, 01:35 PM
X-15 Jockey
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Ok, I did a quick calc, given my wing sweep, etc, a 25% mac gives me about a 62% CG at the root chord, you are flying at around 73%, I'll try some glide tests and see what i see.

Frank


Quote:
Originally Posted by jiberk
I think I setup CG and pivot at 25% of MAC cord. Wing cord at fuse is 9 1/2 inches, CG is 7 inches back from leading edge.




JohnB
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Old Mar 11, 2009, 05:51 PM
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Scottsdale, Arizona
Joined Jun 2006
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Quote:
Originally Posted by jiberk
Hello Frank,

I have a smaller prototype flying, 36" length and 28" wing span. Stability seem be quite good.
Motor is a 2408-21 / BP21 with an 8x4 prop and 1320 lipo. No scale in AZ, weight? Sorry for the bad pictures, cable for good camera is in MN and I am currently in AZ.

I have always been impressed by your profile designs and decide to copy you style.

JohnB

PS - the first drawing is the wing mac and the second is the elev mac
Hey John, have you used that motor for a pusher that size before? I used outrunners on my SSTs (Concorde and Tupolev) recently, with props 8-9 inches across. How is the torque roll for you? How do you deal with it. Man that torque roll made hand launches of my SSTs a real exciting event!

I'm eyeing this thing for a project if the X-24 doesn't work out. Outrunners are my preferred setup, but I'm wondering how others deal with that torque.

Frank- What kind of motor are you using? Looks like inrunner if you are running electric. Do you make your own plans?

Barrett
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Old Mar 11, 2009, 07:25 PM
X-15 Jockey
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Joined Oct 2006
2,443 Posts
Barrett, generally when I do both rocket/electric I use a purple peril running an apc 6x5.5 that I have mounted to a block that plugs into the rocket tube.
On some others I run a grayson 2212-06 running a 6x4 or a super-parkjet running a 7x5. I have not had torque issues, but I'm running 13-15 ounce planes, and can handlaunch at 60% throttle. You do have to watch it on narrow winspan planes running larger props, my x-15, X-24 have a tendency to torque roll. This plane has a very large wingspan compared to others I've built, my X-3 has a pretty short wingspan but doesn't torque much. It also depends on what kind of controls you have, on my X-3 I've got ailerons and you can counter torque pretty quickly, on my x-15 and X-24 I'm running just a full flying tail or flaperons and they aren't as effective at low speed as true ailerons are. These are all outrunners, I like motors in the 1800-2500 kv range, that can spin a 6x4-5.5 fast

Frank



Quote:
Originally Posted by greenseaships
Hey John, have you used that motor for a pusher that size before? I used outrunners on my SSTs (Concorde and Tupolev) recently, with props 8-9 inches across. How is the torque roll for you? How do you deal with it. Man that torque roll made hand launches of my SSTs a real exciting event!

I'm eyeing this thing for a project if the X-24 doesn't work out. Outrunners are my preferred setup, but I'm wondering how others deal with that torque.

Frank- What kind of motor are you using? Looks like inrunner if you are running electric. Do you make your own plans?

Barrett
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Old Mar 11, 2009, 08:38 PM
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Scottsdale, Arizona
Joined Jun 2006
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Quote:
Originally Posted by burkefj
my X-3

I suspect you have Jay Miller's book too. That thing is a bible for guys like us, huh?

Barrett
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Old Mar 12, 2009, 02:19 AM
Vacuum Tubes Forever BCT2/BCR3
MN AZ
Joined Oct 2006
115 Posts
Quote:
Originally Posted by greenseaships
Hey John, have you used that motor for a pusher that size before? I used outrunners on my SSTs (Concorde and Tupolev) recently, with props 8-9 inches across. How is the torque roll for you? How do you deal with it. Man that torque roll made hand launches of my SSTs a real exciting event!

Barrett
I have used the 2408-21 on several plane. The X-2 is my first pusher jet with this motor. Torque on rolls was not a problem, I launch at 3/4 power. On a 3S pack and an 8x4 prop the power to weight ratio in greater than 1:1.

I my try a 2212-06, but on Frank's video the 2000+ kv motor/ 6 inch prop combo sounds noisy (prop noise ?). Noise means you a losing energy/efficiency. I think I calculated a 6 inch prop tip, 2000 kv motor 3S pack, is moving at about half the speed of sound.

Frank, which motor/prop combo do you prefer on the profile pushers?

JohnB
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Old Mar 12, 2009, 09:54 AM
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North Kent, England UK
Joined Jan 2005
301 Posts
Frank, have you had a chance to look at making plans for the Vulcan yet?

Jim
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Old Mar 12, 2009, 12:55 PM
X-15 Jockey
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Joined Oct 2006
2,443 Posts
Jim, MXSPODE volunteered to do one since he was already working on one, he put some top plates in to give somewhat of the "intake" look to it, but then was struggling to hide the battery fully. I can certainly draw one up that's a simple profile, I don't have spare equipment to put into it, if you want to do a beta build and glide tests, let me know.

Frank


Quote:
Originally Posted by JimW
Frank, have you had a chance to look at making plans for the Vulcan yet?

Jim
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