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Old Nov 28, 2012, 08:58 PM
iPhly R/C with iPhone
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Silicon Valley, Calif
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Glad to see you making progress on the X-2, keep them posts coming!

Ari.
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Old Nov 29, 2012, 01:10 AM
X-15 Jockey
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So you are mixing in some aileron reflex/flex to help with pitch control?

Frank


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I flew the little X-2 two more times this past weekend and experimented with mixing some elevator control in with the ailerons and this worked well.
Iím hoping this will help me expand the C/G envelope. Now Iíll install the Eagletree Guardian and see how this works in the little X-2. If it survives these tests then I remove the electric power system and fly it on an ďEĒ

X30
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Old Nov 30, 2012, 05:32 PM
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Yes, I have been experimenting with using the ailerons to assist in both glide trim and pitch control. Anytime you push the speed limits of a flight control system youíre flirting with flutter. One way to reduce this risk is to minimize the size of the surface. This works well but it can lead to insufficient control at low speed.
The tail of the X-2 is small and thin; I want to be able to off load some of the force to the larger and thicker wing. Right now the plan is to use the ailerons for glide trim and reserve the elevator for pitch changes. By doing this the setup is 0-0 on boost and the reflex in the ailerons for glide will also help reduce tip stall during landing.

X30
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Old Dec 03, 2012, 07:18 PM
X-15 Jockey
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That's interesting. I made a note on my X-2 plans that I was just reviewing that said "don't use flaperons, significant pitch down when enabled". So inadvertently I had found that flaperons on my X-2 were very pitch sensitive, down flap pitched down quite a bit....so I think you are on to something.

I've been trying to figure out a way to do a snark but the lack of a horizontal tail and the wings being so far forward always worried me that pitch control would be marginal, however maybe with the sweepback they aren't that far forward....

Frank


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Originally Posted by X30PILOT View Post
Yes, I have been experimenting with using the ailerons to assist in both glide trim and pitch control. Anytime you push the speed limits of a flight control system youíre flirting with flutter. One way to reduce this risk is to minimize the size of the surface. This works well but it can lead to insufficient control at low speed.
The tail of the X-2 is small and thin; I want to be able to off load some of the force to the larger and thicker wing. Right now the plan is to use the ailerons for glide trim and reserve the elevator for pitch changes. By doing this the setup is 0-0 on boost and the reflex in the ailerons for glide will also help reduce tip stall during landing.

X30
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Old Jan 16, 2013, 09:52 PM
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While the holidays were great, it did stop my progress on the X-2.
I finally got back to work on it this past weekend.
The photos below show the process of making the wing tips.
At this time Iím ready to cut out the control surfaces and make provisions for the retractable landing skids.

X-30
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Old Jan 17, 2013, 02:54 AM
iPhly R/C with iPhone
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Silicon Valley, Calif
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Great to see progress on this project! Keep the updates coming!

Ari.
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Old Jan 17, 2013, 12:04 PM
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Truly amazing! Hope you are enjoying the project.
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Old Jan 21, 2013, 06:03 AM
Rockin' & Flyin'
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truly amazing! Hope you are enjoying the project.
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great to see progress on this project! Keep the updates coming!

Ari.
+1
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Old Jan 29, 2013, 11:27 PM
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Iím making a little more progress on the X2.
The latest fuselage photos show the aft tail fairings.
This is the first time that I have put the two wing panels together and itís big.
On the wing photos you can see that I have routed out the cores for the main skid blocks on one side and marked them on the other. Next Iíll cut the control surfaces free and work on hinging them.

X30
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Old Jan 30, 2013, 10:03 PM
iPhly R/C with iPhone
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Big is beautiful!

Ari.
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Old Feb 09, 2013, 09:36 PM
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What's not to like?

Keep it up.
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Old Feb 19, 2013, 12:43 AM
Builder of flying things
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Lookin' good Dave!

Jim B.
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Old Feb 26, 2013, 01:20 AM
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San Jose, CA USA
Joined Oct 1999
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Very neat project! FWIW, I did a rocket powered RC X-2 for the 1978 spacemodeling world championships in Bulgaria. The rules at that time required it to be under 500 grams (17.6 ounces), and with 1978 vintage radio gear, it had to be pretty small, about 22" long. It was exact scale, with scale airfoils (bad). It flew, but the best glide speed was about 60 mph with landings at over 30 (a lot for such a small model!). It was flown with a pair of 18mm Czech "widow maker" D motors.

I did OK in the contest, the problem was that the X-2 was much too simple compared to something like a Saturn 5 or a Vostok. I did get the best flight score of the contest however. I REALLY lucked out in not breaking the air data probe on the nose while landing in a plowed field.

A few comments.. if you do the scale biconvex airfoils, the leading edge wing fences are CRITICAL. Nasty stall/snap roll/ spin if one happens to get knocked off. (I speak from experience! If not for that, the model would have ended up in the National Air and Space Museum.. oh well)

Also, note the elevator setting for boost in the first photo. I had the scale full flying stab, and it really really wanted to trim there. Before flying the true scale model, I made a simple one with a box fuselage and it wanted the same elevator trim. If you can modify your little model for boosting that might help sort things out, but I am not sure your profile fuselage will have the same stability effect as the scale one.

Good luck with it! I want to see some flight photos!

Bob Parks
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Old Feb 26, 2013, 01:13 PM
X-15 Jockey
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Bob, it looks like your up trim is just an artifact of offset thrust line above the wing..do you think it was due to something else?

On my profile version I'm using a low thrust E-6 and I don't have much up trim on bost at all, so some of the boost trim you saw may have been due to the fuse shape.

Frank
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Old Feb 26, 2013, 10:07 PM
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Hi Bob,

Thatís one great looking X-2 you built! I agree that was quite accomplishment making the completed model under 500 grams with the available R/C gear at that time. Iím sorry to hear it had an untimely demise.
One of the issues we had was trying to find good documentation. It seemed a little challenging as none of the X-2s survived. Some of the photos we saw did not concur with the 3 view drawings. You obviously did a great job on your documentation.
Unlike your beautiful exact scale model, the engineer helping me with this project and I have taken some liberties with the design to simplify construction, transport and flyability.
You can see from the CAD wing drawings that Mike Oser produced; the airfoil we selected is not scale. We also have one 3-inch motor mount on the centerline to simplify thrust issues. Unlike the full sized aircraft I am going to use elevators with a fixed stab. Getting a full flying tail working well on this model considering its size and speed looked problematic.
I did test using some up aileron for glide trim and this worked well. It also creates a little washout at the tip to help prevent tip stall issues.
Any input and documentation you can provide would be greatly appreciated.


Thanks

X30
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