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Old May 16, 2009, 03:59 PM
Detail Freak
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Harbor City, CA
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Maybe...

Thanks.

Target
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Old May 16, 2009, 11:16 PM
Fly R/C writer
Redlands, Ca
Joined Dec 2004
1,887 Posts
Hi Phil,

Control throws....okay, but one bit of caution: As a former pattern pilot of 18 years, I had a tendency to make my control surface movements quite radical compared to most people. This is because when I nailed the aileron stick, I expect that the plane will move right now. This followed me into sailplanes, so if you are going to use my control throws, don't get mad at me if you find the plane reacts a bit too fast for you. As they say, your actual mileage may vary.

Ailerons: 1/2" up, 3/16" down measured at root
Elevator: As much as I can get both directions. But definitely at least 5/8" down at TE.
Rudder: 3/4 inch left, 3/4 right at bottom of rudder.
Flaps: 90-degrees down, 1/8 inch up.
Flaps are mixed to the ailerons to move 1/8" up and 1/8" down in same direction as ailerons. Never turned off. (When I want a roll, I want a roll!)

Launch mode: 1/4" flaps down, ailerons to match that angle, no elevator, tow hook at 1/16" ahead of the CG.

Cruise mode: Aileron to rudder mix = Ail - 100% and Rudder - 45%

Thermal mode: 3/32" flap down, ailerons to match at TE, ail to rud mix at 52%.

Reflex mode: 3/32" flap up, ailerons to match, no ail to rud mix.

CROW setting: Initial is 90-deg flaps, 5-deg ailerons up, elevator to compensate. Depending on the initial set up and sink rate, I adjust the ailerons to increase or decrease the sink rate. Raise the ailerons to increase sink, drop the ailerons to get more float. For the most part, the X has great brakes, and so sinking the plane is not a problem and most of the X drivers I know do not use a lot of up aileron. If anything, you better learn how to modulate the flaps, because this plane will stop quickly if you leave the flaps fully deployed....this normally means landing very short of the spot!

I hope this helps. The new X-38 is ready to go and we should have her airborne on Sunday. All systems checked out fine on the ground and double checked for accuracy. Somebody is bound to ask, what does it weigh. I can only say that if I told you, I'd have to kill you...all! This plane has a classified weight. All I can say is that this one is light! If somebody asks me to repeat any statement related to the weight, my answer will be, "I'm sorry Mr. Chairman, I do not recall that statement." Final balance point will be determined at the field. I'll get back to you all after we get back.
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Old May 17, 2009, 03:00 AM
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Quote:
Originally Posted by ScabbyNubtail

Bob at Susa can sell you these connectors...
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Old May 17, 2009, 04:59 AM
Tragic case
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Sydney Australia
Joined Feb 2002
5,866 Posts
Quote:
Originally Posted by target
I'd be interested in that, David.
Will it fit in the same space that the DB9 will??

Never seen one in the USA.

Target
Here is the MPX version from a good online shop

http://www.aircraft-world.com/shopexd.asp?id=784
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Old May 17, 2009, 10:17 AM
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webbsolution's Avatar
Joined Jul 2007
2,771 Posts
Quote:
Originally Posted by mlee8249
Hi Phil,

Control throws....okay, but one bit of caution: As a former pattern pilot of 18 years, I had a tendency to make my control surface movements quite radical compared to most people. This is because when I nailed the aileron stick, I expect that the plane will move right now. This followed me into sailplanes, so if you are going to use my control throws, don't get mad at me if you find the plane reacts a bit too fast for you. As they say, your actual mileage may vary.

Ailerons: 1/2" up, 3/16" down measured at root
Elevator: As much as I can get both directions. But definitely at least 5/8" down at TE.
Rudder: 3/4 inch left, 3/4 right at bottom of rudder.
Flaps: 90-degrees down, 1/8 inch up.
Flaps are mixed to the ailerons to move 1/8" up and 1/8" down in same direction as ailerons. Never turned off. (When I want a roll, I want a roll!)

Launch mode: 1/4" flaps down, ailerons to match that angle, no elevator, tow hook at 1/16" ahead of the CG.

Cruise mode: Aileron to rudder mix = Ail - 100% and Rudder - 45%

Thermal mode: 3/32" flap down, ailerons to match at TE, ail to rud mix at 52%.

Reflex mode: 3/32" flap up, ailerons to match, no ail to rud mix.

CROW setting: Initial is 90-deg flaps, 5-deg ailerons up, elevator to compensate. Depending on the initial set up and sink rate, I adjust the ailerons to increase or decrease the sink rate. Raise the ailerons to increase sink, drop the ailerons to get more float. For the most part, the X has great brakes, and so sinking the plane is not a problem and most of the X drivers I know do not use a lot of up aileron. If anything, you better learn how to modulate the flaps, because this plane will stop quickly if you leave the flaps fully deployed....this normally means landing very short of the spot!

I hope this helps. The new X-38 is ready to go and we should have her airborne on Sunday. All systems checked out fine on the ground and double checked for accuracy. Somebody is bound to ask, what does it weigh. I can only say that if I told you, I'd have to kill you...all! This plane has a classified weight. All I can say is that this one is light! If somebody asks me to repeat any statement related to the weight, my answer will be, "I'm sorry Mr. Chairman, I do not recall that statement." Final balance point will be determined at the field. I'll get back to you all after we get back.
I am Canadian sir so you see your statement to the chairman holds no value to me...Classified oh but you forget the North America Free Trade agreement....so like our water and other resources you have to freely and without undue tarif export this information north of the border.

On a more thread related topic though

[QUOTE]

Flaps are mixed to the ailerons to move 1/8" up and 1/8" down in same direction as ailerons. Never turned off. (When I want a roll, I want a roll!)
[End Quote]


Your input as a pilot and a builder are both superior to mine so my statements are not intended as a challenge to your inout but rather another perspective.

This is an area that suprised me when I setup my plane (coupled VS uncoupled response). Have you tried it in a mode with this setting off yet? It seems like a different plane to me between coupled flaps and uncoupled. On one side I really like having a lot of control down low when I get into one of those low moderate thermals that you need to fly DLG style but when I run into an area that is just barely positive lift and I turn off the coupling I feel like I can gain better without the extra drag of moving a flap surface.

Yesterday was a great example of that rare neutral air. I had at least an hour an a half of zero wind, moderate humity and what appeared to be neutral air. Its all about efficiency at this point since the only thing you might find is something that can just maintain you. In the uncoupled mode (with also reduced input responses) the plane just hung out forever. I did a 13+ minute flight most of which was at 45 feet. Then the air turned more positive and it didn't matter what mode you were in.

Of course I have to remember that you live in California and your concept of a thermal is a little different than mine.

Out in BC in the Fraser Valley our thermals can be really light so this kind of a setup is more important...unlike the thermals I saw at Visalia ...where you knew there was a thermal coming because the dust it picked up blotted out the sun...
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Last edited by webbsolution; May 17, 2009 at 10:34 AM.
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Old May 17, 2009, 01:37 PM
In F3J size does matter!
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Israel
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827 Posts
"13+ minute flight most of which was at 45 feet" - don't know, sounds like it wasn't quite that neutral...
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Old May 17, 2009, 01:51 PM
Registered User
Sarasota, FL
Joined Jan 2006
175 Posts
Mike,
Thank you very much for the information. I will use this as a starting point on the Xplorer.

I appreciate your pictures as well. I'm sure many of us look forward to your postings.

Phil.
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Old May 17, 2009, 02:54 PM
Fly R/C writer
Redlands, Ca
Joined Dec 2004
1,887 Posts
It is airborne!

Okay, so we had wonderful sunny California skies with highs hitting about 90f and a slight breeze every once in awhile. A complete range check was performed and then three people to rundown the control motion check. A hand toss was great and the plane was showing her to be a floater...so far so good. Only one thing left to do...winch it!

So, with normal winch line tension, I gave it a throw only to break the line 2-seconds into the launch. It didn't matter....11-minutes later, it landed! Great float, very good thermal detection, the roll rate is very nice despite having these long wings and the elevator is quite positive. It does not roll as snappy as the original X, but plenty fast enough for the majority of pilots. I did end up increasing the rudder mix from 45% to 60% and that made turns much smoother and progressive. I also added 4% more aileron up for the CROW as the plane simply floated too much. Four pilots took their turn at the sticks and all were very pleased with the handling. One of them was Bob Breaux of SUSA, and he was wringing it out with full elevator applied to a hard banked turn. The plane did not stall out. It just kept turning and burning.

Launching is pretty darn stable, being almost hands off and steep. It does not carry the zoom as long as the original, but it is not disappointing, either.

Now, we have been granted permission by the authorities at SUSA to release that classified information...71-oz. That makes for a wing load of a hair above 8 oz/sq-in. This is the perfect early morning, late evening, no lift condition aircraft!
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Old May 17, 2009, 03:01 PM
Fly R/C writer
Redlands, Ca
Joined Dec 2004
1,887 Posts
To Webbsolution,

I understand what you say about not using the ailerons coupled to the flaps. And to be honest, I have been in such a habit of using coupled flpas/ailerons for so long, it is just normal for me to program them in. I reckon I'll just have to try it and see how I like it.

I originally started coupling up when flying the Lazurite many years ago, and this plane simply had a lack of roll response until I coupled the controls. That cured that and I have coupled ever since. But I will try it and see.

As for that trade agreement between the countries...come and get me! "You'll never take me alive, copper!"

BTW, Les Ward at our field also put up his X-38 and it also was a pleasing experience for the pilot. His balance point was similar at 106-mm. Thanks to all of you guys who have asked about this plane.

Sincerely,
Mike Lee
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Old May 17, 2009, 03:30 PM
In F3J size does matter!
roydor's Avatar
Israel
Joined Nov 2006
827 Posts
Mike, what's the lay-up of your plane? d-box?
Are the spars full strength? will it take windy launches? lets say up to 10-15 knots? more than this?

Webbsolution,
Mixing flaps with the ailerons actually reduces drag (up to a point), the reason lays in dampening affects of the center panel during roll rate of the wing.
For example, if you create a roll rate with the ailerons and then return them to neutral, the glider will stop the roll without the need to introduce opposite aileron.
This is caused by the fact that the wing going down is seeing a higher angle of attack and the wing going up is seeing a lower angle of attack. This causes an increase of lift in the wing going down and decrease of lift in the wing going up. The asymmetrical force causes a dampening affect and stops the roll. The faster you roll the grater the dampening. When you couple the flaps with the ailerons your not really creating roll, its to little a moment to create a noticeable amount of roll. It is however enough to decrease the amount of dampening from your center panel considerably and as a consequence it increases the effectiveness of the ailerons, hence grater roll rate. The longer the center panel the grater the difference.
Because the dampening affect is roll rate related and while flying in very calm conditions you're flying with small stick movements, the amount of flap coupling required is reduced considerably. I use about half of the aileron movement in speed mode, a third in cruise mode and only a quarter in thermal mode with my Perfect.
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Old May 17, 2009, 04:41 PM
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webbsolution's Avatar
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Quote:
Originally Posted by roydor
"13+ minute flight most of which was at 45 feet" - don't know, sounds like it wasn't quite that neutral...
Yea ok I get your point. It was postive but only just barely so..
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Old May 17, 2009, 08:15 PM
Detail Freak
target's Avatar
Harbor City, CA
Joined Oct 2003
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My maiden experience was similar, with a 10-12 minute flight spent at about 75-100' of altitude, much to my surprise.
I would have to say that now, I would have done much better, I think!

R,
Target
PS. I also believe in coupled flaps to ailerons. Coming from the sloperacing discipline, I can tell you that this allows less overall throw/drag for the same response wanted. Always a good thing.
For David, have you tried coupled flaps with just way less throw overall, as your light lift settings??
That's the direction I would go.
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Old May 17, 2009, 09:16 PM
RIP MC
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United States, CA, Midway City
Joined Dec 2003
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Flaps coupled to Ail

I have tested this out on a few ships over the past couple years and will say that I always run coupled flaps with ail in all modes.

Without coupled flaps to ail, the controls were more sluggish and of course the ail needs to move much more to yield same roll rate. The key is how much to couple them. Dr. Drela had provided a scientific reason to use it and a formula but I can't find it.

It goes something like this: The perfect roll movement is a twisting wing with zero twist at the root and progressing to more twist at the tips. But since our wings are made for no flexing we can "twist" the trailing edge to simulate.

So it reasons that the flaps should move a percentage of the ail. According to Drela's theory, if the flaps were the same length as the the ail then a 2:1 movement of ail to flaps would be appropriate (flaps move 50% of ail). If flaps were 40% of Ail length, then flap movement would be less than 1/2 of ail movement.

The only way I have found to be accurate with this is to place a piece of paper in between the center panel and tips when sliding the tips on. With a reference line drawn (LE to TE) and make mearsurements against the line.

On my X the Flap/Ail are a little less than 1:2. About 2:5. Now if we extrapolate this to the Xtended tips, it should be that the flaps now should move less and/or the Ail throws should be more. Calculated wouwld be about 1:3 coupled Flap to Ail. Looks like Mike Lee is running :4.

The other thing that Dr. Drela says it helps is reduce tip stalling tendecies. That, I believe is one of the best reasons to use A+F when low, slow and praying.
TL
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Old May 17, 2009, 10:02 PM
Registered User
Brea, CA
Joined Feb 2007
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Flap/Ail Coupling

Tuan;
You are close but here's the quote of Dr. Drela, written by Daryl Perkins.

Aileron/Flap Coupling

The original question is about aileron to flap coupling. I've been using this for years, regardless of airframe. I found it to aid in all handing characteristics. Increases roll rate while reducing total throw required in all flight modes, reduces adverse yaw tendencies requiring less aileron to rudder coupling.
From Dr. Drela:
Deflected ailerons deform the load distribution away from the ideal near-elliptical shape, and hence increase induced drag. Partially slaving the flaps to the ailerons can alleviate this load distribution deformation, and thus mitigate the ailerons' CDi penalty. The question is what's the optimum amount of ail-> flap mixing.
The lowest-drag aileron system is wing-warping as used by the Wright Brothers -- the wing is linearly twisted from tip to tip. When such a twisted wing reaches its steady roll rate, the load distribution returns to its optimum level-flight shape, and the drag penalty is zero.
With a finite number of hinged control surfaces such a linear twist cannot be achieved. But it can be approximated as close as possible if each surface's deflection is made proportional to its distance from the aircraft's centerline, measured at the surface midpoint.
If the four control surfaces have equal span, we then have:
Surface mid-span loc. deflection
L.Aile. -3/4 -100%
R.Aile. -3/4 -100%
L.Flap. -1/4 -33%
R.Flap. -1/4 -33%
So for this wing the flap motion should be 33% of the aileron motion. Using AVL I've verified that this mixing ratio produces very nearly the smallest induced drag penalty. If the flap span differs from the aileron span, the table above can be adjusted accordingly.
Longer flaps will have larger travel and vice versa.
BTW, this "distance-proportional deflection rule" strongly argues against stopping the ailerons short of the tip. The resulting unhinged tip portion should in fact have the largest deflection.
The "distance-proportional deflection rule" can be fudged if there is a tip stall problem in a sustained turn, where some opposite aileron must is held. By increasing flap travel over its "optimum" amount, the flaps can carry a greater share of the roll power, which reduces the required downward deflection of the inside aileron, and thus delays tip stall. So if your TD glider has insufficient tip stall margin, I suggest increasing the flap mixing and you should see some improvement.
The extreme case would be 100% flap mixing, which mimics full-span flaperons. Flaperons give excellent tip stall resistance, as is obvious to anyone who flies a DLG with a good 2-servo wing. A 4-servo TD wing with decent planform should not need to go to this extreme.
I have some time on a Perfect. Yes, I coupled the ailerons to flaps with good results. I probably run more than Dr Drela suggests.
Good luck with it!!! dp

Just happened to have it in my files as I like to save useful data from talented people.
Enjoy,
Don
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Old May 17, 2009, 10:50 PM
RIP MC
fnnwizard's Avatar
United States, CA, Midway City
Joined Dec 2003
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Ahhhhh, DL... thats it! Thanks!
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