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Old Jan 27, 2013, 09:04 PM
Firepower
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North Brisbane, Australia
Joined Mar 2010
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Quote:
Originally Posted by hoeniola View Post
CG is a little bit behind the 2 nipples on the bottom of the plane. about a quarter inch behind the nipples.
Good to see you have the X5 flying and saw the inside of yours elsewhere and got some ideas.

You might know more than me on the c of g seeing you have yours flying but may be yours has a problem in the turns is that you have the c of g too far back.

Have you tried the c of g further forward at 10.5 inches like the bloke shows in the video. I need to get this right for when I try mine which will be a while yet. But further forward usually make wings fly worse.

SkyWalker X5 Maiden Flight (3 min 2 sec)
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Old Feb 09, 2013, 08:44 AM
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Joined Feb 2013
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X5 Maiden

Eflight park 450
3s 5200mah
9x6 prop
30A esc

With the battery mounted horizontally, against the forward balsa block it fit really great and cg was just forward of the finger hold. This thing basically just fluterred out of the sky like a drunken butterfly..Impossible to fly.
I confess that I hadn't shimmed the top of the motor..Will it make that big a difference in the way it flys? or is my cg that far off towards the back?

(btw, my friend attempted his first hand launch for me and got cut to the bone, it was a blood bath!
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Old Feb 10, 2013, 03:28 AM
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Sweden, Umea
Joined Nov 2006
237 Posts
Quote:
Originally Posted by marce002 View Post
Ok I have figured out a way of postprocess a lot of photos with a gps gpx log for example, if anyone is interested i can explain, but basically is a software that stamp into the exif data, the precisa gps time when the pic was taken..
That would be interesting hearing about,

im doing the same thing but with palantier and the log file from mikrokopter.
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Old Feb 10, 2013, 06:11 PM
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Canada, NS, Halifax
Joined Dec 2005
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CG May be off a bit

Quote:
Originally Posted by Jimmyjames916 View Post
Eflight park 450
With the battery mounted horizontally, against the forward balsa block it fit really great and cg was just forward of the finger hold. This thing basically just fluterred out of the sky like a drunken butterfly..Impossible to fly.

I am still building my X-5. I measured the CG marks on the fuse bottom and they are almost 1.6 inches ahead of the finger hole. If you have the CG too far aft, most flying wings will be virtually uncontrollable.

So depending on what you regard as " just forward of the finger hold" (hole?) If you mean just forward of the hand hold on the bottom, the sort of landing skid, then it is waaaaay to far forward. If you mean just forward of the finger recess then the CG may be too far aft. This would make the plane difficult to fly, if at all.

I would start by setting the CG 1-9/16ths or 1-5/8ths ahead of the finger recess or hole in the bottom. This is about 10-1/2 inches behind the very tip of the nose of the fuse or body form.

From experience flying Electra Jet, Fun Jet and Sup-RFly I can assure you if the CG is too far aft you will not be successful.

The other suggestion I can make is to NOT launch with full power. For example the FunJet directions clearly say to launch with 50-70 % throttle. The reason is to avoid torque roll caused by maximum motor torque, but not enough speed for the ailerons to be effective.

All these delta wings were and are a hoot to fly. I expect my X-5 to be a more sedate version with good payload.

I will also be stabilizing mine at launch with the GluonPilot2 found at www.gluonpilotusa.com

Update : I never did use the stabilized mode on launch and should have!
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Old Feb 12, 2013, 06:52 AM
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United Kingdom, Bradford
Joined Jul 2010
92 Posts
I have to agree having the cg slightly forward does help, our X5 had 3 very short unstable flights before i move the CG forward, defiantly improved it no end. As regards launching we added some landing gear, a tripod arrangement , not pretty but works well if your on a hard surface.
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Old Feb 26, 2013, 06:24 AM
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United Kingdom, Barrow-in-Furness
Joined Feb 2011
371 Posts
Nearly finished my X5

I've nearly finished my X5 build and still pondering the mysteries of CG and thrust angle. I read somewhere that the canted wintip version had had it's thrust angle corrected but according to this thread people are still using the small wooden spacers.

Ain't life fun.

Skywalker X5 flying wing build part 1 (14 min 55 sec)


Skywalker X5 flying wing build part 2 (11 min 23 sec)


Skywalker X5 flying wing build part 3 (13 min 21 sec)


Skywalker X5 flying wing build part 4 (14 min 53 sec)


The remainder of the build log will be uploaded in the next couple of days.

Col.
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Old Mar 04, 2013, 09:32 AM
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Canada, NS, Halifax
Joined Dec 2005
279 Posts
Canopy hold down on X-5

I am in the process of building my X-5. I was not comfortable with the canopy hold down. I want to be able to open the canopy quickly to change batteries and connect the USB cable to my GluonPilot 2 autopilot

So I followed the manual and cut off the canopy front tab that is part of the nose camera support and glued it in place using FoamTac. Then I marked the front edge of the canopy at the bottom of the cut off foam. I then cut and glued in place a light ply tab or tongue to hold the front edge of the canopy in place. I will use magnets mounted in the side about 2/3 or 3/4 of the way back, on each side to hold the canopy down.

You can see the 900 Mhz antenna sticking out of the top of the canopy, and can barely see the GPS recessed into the left wing and sealed with white silicone bathroom seal.
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Old Mar 11, 2013, 04:24 PM
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Canada, NS, Halifax
Joined Dec 2005
279 Posts
X-5 Canopy and CG update

After testing and 2 successful flights the 3rd flight had the canopy blow off.

The causes for losing the canopy were several.

Speed. The plane sped up in a shallow dive to a lower altitude. The camera opening in the nose acts as a pressure source for
the inside. In other words the camera opening has to be taped over or a vent hole of twice the area has to be made at the rear of the canopy.

When you consider the area the pressure was acting on it did not take much to overcome the pull of the magnet set. So next time I will add 2 magnet sets and a vent hole in the rear of the canopy.

Lift. There is a lot of aerodynamic lift on the canopy. The large lifting surface just lifts more with increasing speed.

The CG was right on the marked nipples on the bottom of the fuse. The camera was an 808-16 V1 with lens A


This is a video of the canopy blowing off and falling to earth. The camera was on the canopy. The plane was being guided by a GluonPilot2 autopilot from www.GluonPilotUSA.com

GluonPilot2 on a SkyWalker X-5 over Lieblin Drive Halifax Canada (3 min 46 sec)
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Old Mar 11, 2013, 08:03 PM
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United States, CT, Fairfield
Joined Jan 2012
510 Posts
How well would you say the X5 is as an airframe for the GluonPilot (or any FC)? I had an X8, but it's just too big to transport, too structurally weak, and too heavy to launch, so it's not very good for aerial mapping anymore. I've heard some people calling the X5 a "whale," and a "horrible airframe layout," but I'm not sure whether they're being accurate. After all, the eBee and X100 (sensefly.com/ebee and gatewing.com/x100) both look quite a bit like it. They do have their differences, though.

What's your personal opinion on it? Also, what kind of range do you get with it?

Another concern: how does its payload capacity compare to that of the SW 1900? Are they equivalent? Could it carry more than one Canon P&S?
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Old Mar 11, 2013, 08:03 PM
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Old Mar 12, 2013, 04:40 PM
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Canada, NS, Halifax
Joined Dec 2005
279 Posts
X-5 Analysis

I have flown 3 flights. All were hand launched. The day had 12-15 MPH wind gusts. Launches were done at half throttle or a little above. Before adding 2 small batteries as ballast to correct the CG, the complete plane with 3S2200 LiPo weighed 737 grams.

There was no camera in the designated position inside. This position is mostly ahead of the CG so adding a camera there would have reduced the need for ballast in the nose.

The plane is not steady in flight. It bounces around in manual flight. It flys better at a slow speed. The GluonPilot2 held the plane very steady in the first autonomous flight at the slower speed. I also increased the aileron gain for the last flight. I will roll it back for the next flights. So slower flying with lower gains should make a more stable platform.

I found the wide shallow interior space hard to work with. I am more used to a taller skinny fuselage, such as the TwinStar, EasyStar and most conventional planes. It may be just me.

There is a lot of room. The canopy hold down that is from the factory is not the most usable design. I had put a tab under the forward end and 1 set of magnets at the centre rear of the canopy. On the repair I will add a vent in the rear of the canopy to release the pressure build up and I will put a piece of tape over the opening in the very nose. I will change to 2 magnet sets, one set on each side, to hold the canopy down.

The initial test flights were close in, maybe a couple of 100 meters away and a maximum of 120 meters high. The orientation of the plane in the air is hard to see. At any distance away, a side view does not let you know if it is banked to or away from you. I will add some International Orange to the underside of the winglets to help visibility.

The longest flight was some 13 minutes. It used less than 1000 ma. So I can hope for a good 25 minutes on a 3S2200. At 40kph that is about 16.6 km of flight. Say 5km out, 5km back and 5 km circling an object taking pictures and little or no reserve.

Range or endurance will be reduced by adding a camera. Most point and shoot digital cameras weigh about 125 to 160g. This would bring it right around the 900g weight which the vendor suggests. So maybe 14km flight endurance is a better mark. Flights later this week will be better documented battery wise and speed wise. I will change the flight plan and make longer straight runs to better judge the stability and endurance.

I am building an SW1900 black as well. My first bet is that at slow speeds the 1900 will have better stability, longer range and more carrying capacity. I plan to use the GluonPilot autopilot as well in that. I have 3s5000 LiPos for it.

Stability of the 1900 will be improved because of the pendulum effect and dihedral effect of high wing placement. Because of the long span and large wing area the plane should carry more weight and that translates into battery and therefore range. I will be using a modest motor of about 180-200 watts. That puts it in the 60 watts per pound range. The larger a plane is the lower the watts per pound is required. The power is limited anyway by the size of the prop that you can use. I am looking for overall efficiency not high speed.

The space to install any camera inside out of the slipstream means that whatever you add does not increase drag. Sometimes people forget that drag is drag whatever the size of the plane. Clean lines, taped joints and taped gaps all help, even at low speed.

On the X-5 I installed the motor inside the existing motor housing, not sticking out the tail in the breeze. This took some cutting but it reduces the polar moments of inertia and reduces drag. I may further sand and shape that ugly unfortunate bump that is the motor mount / housing, to reduce drag and improve airflow to the prop.

Any camera inside the X-5 has to point almost straight down. The SW 1900 could do the same if photo mapping is your objective.

The fuselage of the X-5 has some flex in it. However it is strong enough to fly for the intended use. It is not aerobatic. It is not designed for aerobatics. Do aerobatics and it will break. Adding carbon rods, balsa or ply reinforcements, landing gear, etc are not what this is designed for. It is designed to fly in a specific role at specific weights. Load it up, over fly it and it will likely break. All planes designed for specific roles will break when used outside those roles.

It is not suited for a DSLR in my view. If you had 2 small size P&S digital cameras then they may fit in. Some of the very small Canon units may permit 2 to fit in. It would be tight and I would think that 2 flights with 1 camera should get the overlapping pictures you might be aiming for.

Further flight testing will reveal additional results.

Summary : Hand launching was not traumatic. Weight was within recommended limits. The plane flys easily. Orientation at a distance was hard to determine. The GluonPilot 2 was easy to configure and flew the plane out of the box with default settings. 1 camera would fit well. Fly it slowly for best results. Build it to fly not to crash.

Update : Subsequent hand launches were quite traumatic. Torque rolls were an issue when testing with various props on later flights. Major repairs are now required. 8-))
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Old Apr 21, 2013, 09:30 PM
Inherent Tinkerer
Wichita, Kansas, USA
Joined Jul 2003
1,428 Posts
I finished an X5 build for a client today. The plane it pretty interesting but there are a couple of things that I don't like:

The stock plane is really tail heavy and requires a large battery or ballast to get the CG right. This plane has an Eagle Tree Guardian in it and the customer supplied his own radio and battery (1300 mAH.) I had to add some lead to the nose to get it to balance. I would add a larger battery to balance it if it was mine.

The second thing I don't like is how flexible the fairing that the motor mount attaches to is. I added some .75 oz glass to strengthen that area and it should be really strong now (proved it's strength already today.)

The one thing I REALLY don't like is how the canopy mounts. There are two screws that are put through holes in the canopy and screw into blind nuts in the fuselage. Although they line up pretty well it takes me too long to align the screws with the holes to attach the canopy. I'm sure it looks good on paper but in practice it really stinks. The screws would also flop over in the hole and start digging into the foam. I cured that by putting a 1/2" section of the proper size carbon tube at the bottom of the hole that keeps the screws lined up and protects the foam from the screwdriver.

I was given a bottle of the new BSI EPP glue to try by my local hobby shop and tried it on the X5. While the glue seems to work really well when using on two EPP surfaces it is lacking when used where wood is attached to EPP. When my son launched the plane (really hard to grip for a good launch) he gave it a shove as he let go and it rolled upside down. I was able to get it back right side up right away and it plopped softly onto the grass in front of us. The glue that held the motor mount on let go and it fell off the plane (no damage, just a clean separation of the glue.)

I've reattached the motor mount and will give it a try this week.

Cheers,

Jimmy
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Old Apr 22, 2013, 08:17 PM
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Canada, NS, Halifax
Joined Dec 2005
279 Posts
X-5 Follow up

I experienced similar aircraft upset on launch in subsequent flights.

In careful examination of the airframe I observed that there was anhedral in the wings. In other words negative dihedral. This is usually used in aircraft with the wing above the vertical center of gravity and with a large distance between the vertical center of lift and the vertical center of gravity. The X-5 cannot be loaded in a manner to have this condition.

I have put the plane aside to concentrate on the Skywalker 1900. If I do go back to the X-5 I am considering chopping the wings off and sanding dihedral in the root. This will improve the inherent stability which is lacking now.

Regarding the hatch tie down. For some reason my X-5 came with a short note saying to cut off the short piece of foam on the front of the hatch, and to then glue this piece in place on the fuselage. After doing this I then added a small light ply tongue to hook under the piece glued in. This was combined with a magnet pair at the rear. This canopy blew off in a subsequent flight as detailed above. I did not use the included hatch tie down of screws and ply plates. I was not planning to use a camera mounted to the top of the hatch and so felt that the bolt on method was a not required.

I then added two Du-Bro hatch latches at the mid point of the sides and had no further hatch issues.

If I do test fly the X-5 again, I will launch with the GluonPilot2 in stabilized mode to ensure the craft is stabilized during that critical phase.

I do believe the design may have inherent stability issues.

Life is too short to spend a lot of time debugging such a design.

Regarding the motor mount. I did not mount the motor as intended. I mounted the motor INSIDE the motor fairing. I used an aluminum plate mounted to the motor and then bolted to the ply plate. This has proven very durable. I will post pictures next week detailing this.

I did use Foamtac glue during the assembly. I find it is more flexible and resilient in impact conditions. It flexes at a similar rate to the foam. I feel Epoxy and CA glues tend to be too rigid or brittle in this application.

Jim
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Old Apr 22, 2013, 09:12 PM
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Near Austin
Joined Dec 2001
5,380 Posts
The X5 (nor the X8) is a good interpretation of a flying wing platform. These are the kind of plan forms that gave the flying wing a bad name early on in the game (around the turn of the century). Look at either the Foamaroo or the Spectra and you will find nearly ALL the bad habits mentioned in the above posts have been bred out.

Just my 2 centavos
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Old Apr 24, 2013, 07:00 PM
Inherent Tinkerer
Wichita, Kansas, USA
Joined Jul 2003
1,428 Posts
Flew the X5 today and was pleasantly surprised by it. Had a slight drop in altitude when launched but was able to climb out with no problems and very little trim was required to make it fly level. The first flight was done with the Guardian turned off so I could trim the plane. I set up to land and it slowed down nicely for a soft touchdown.

Second fight was done to tune the Guardian. The customer's radio only has a two position switch for mode select so the stabilization is always on. We launched again and the Guardian worked like a champ.

I think keeping the wing loading down is a major factor in how it flies so a battery just large enough to balance it is a good thing. Also, launching it gently will reduce the tendency for it to roll over when released. I hand launched it on the third flight with the stabilization turned on and it launched very well.

The plane flies ok but I really prefer how the Foamaroo or a Spectra flies. Both of those airframes can carry weight with no bad side effects. I think the X5 would be a handful with much more weight than I have installed.

The pictures of the plane show my radio/Guardian install as well as the reinforcement of the rear of the fuselage.

Cheers,

Jimmy
www.hangar18uav.com
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