What to do with a Art-Tech Wing Dragon?

[quorneng]

Some 3 years ago I bought my first electric RC plane - an RTF Art-Tech 4ch Wing Dragon. Brushed 480 motor and a 1000mAh 9.6V NiMh.

Simple and robust (almost crude) with a modest performance and limited endurance but it 'did what it said on the box'! As I fly from a rough grass field it soon became a hand launch/belly lander.

To my mind the solid foam wing was unduly heavy for what it offered. I had intended to make a new built up balsa one but at about the same time I came across 3mm Depron sheet. 1/10 the weight of balsa, very easy to cut and glues well. What if I simply made the new wing in exactly the same way but in Depron?

Exactly the same span (40")and chord as the original, with a standard Clark Y section the wing was thick enough to need no reinforcement. The skin would carry all the load - I hoped!
The only balsa was the leading edge.

5g aileron servos built in to the wing structure with just the tip of the servo horn protruding. With the horn angled forward by 45 degrees to give a differential (more up than down) aileron movement to reduce aileron yaw.

It gives a very smooth bland surface.

The ailerons are top hinged with sellotape that makes a simple and flexible hinge.
The new wing complete.

The new wing weighed just half the weight of the original and was aerodynamically more efficient so it now could actually glide quite well.
With differential ailerons the rudder was not really required so more weight was saved by removing the servo and its linkage so it became a 3ch 'bank and yank'. Note the repaired RH wing resulting from a high speed crash.

The weakest point on the Wing Dragon is its low set tailplane so I made up a 'elevator only' V tail.

This also reduced the drag a touch as the tail surfaces were no longer directly in the prop wash.
It was now a nearly 4 ounces lighter so had a performance well beyond stock and could be looped and rolled with ease.

Next brushless and LiPo.

 

[UndCon]

I'm not sure about the span of that wing but I made a wing from Depron and it had no spars at all - 80cm span in total.

It was also Clark-Y-ish..

//UndCon

 

[earthsciteach]

Just curious, how did you shape the balsa leading edge?

 

[quorneng]

earthsciteach
The leading edge is 1/2" square soft balsa sanded inside and out. Quite a tedious process but it was my first wing using Depron so I reverted to a process I understood. I hollowed it out simply because l felt the solid the balsa was rather heavy compared to the Depron.
Now I make the LE from solid Depron sanded to shape.

Undcon
Span 40" = 102cm.

As I was trying to save weight rather sheer power I chose quite a modest (and cheap!) LiPo and brushless set up, 1500mAh 3s and an Emax 2812 1500kV driving a 7x4 prop. About 150W (50% more than stock) but 3oz lighter.

It obviously had a huge performance compared to what I started with but the very low wing loading made it tricky to fly in any sort wind so I built a tapered Depron wing with the same 40" span but just 70% of the area.
This time the wing was built around a tapered balsa/depron/balsa box spar.

It looks quite skinny compared to the original.

The other major modification was to do away with the fuselage mounted servos altogether and install the micro 3.7g elevator servo in the Depron fin with a mid mounted Depron tailplane.

This is recent picture so fin is showing signs of a hard life!
Painted a gaudy yellow and red.

It now weighed 17oz but that includes the 2 extra 5g servos to work the big flaps!

At full 70 degrees the landing speed is low!

Of course now only the bare fuselage shell and the tail boom remain of the original Wing Dragon but then not much of its original performance remains either!

And its no '3 minute' hot rod either it can keep up that sort of flying for close to 10 minutes (I am not sure I could!) and potter about for nearly 30 (now I can do that).

What would happen if I made the wing even smaller?

 

[UndCon]

Here is the swedish build log from my Depron Kobra
(Lots of pictures)

 

[quorneng]

UndCon
Nice and neat!
As the size and weight go up a Depron wing like that needs reinforcement.

I have found it is possible to form Depron round quite a small radius, particularly with 2mm, provided you do it across the grain.

A piece of 3mm Depron 'formed' into a 3/4" (20mm) radius.
Of course double curves are not possible so for that you have to resort to planking.

 

[quorneng]

The next wing again retained the 40" span but reduced the area down to 55%.
As this was going to have a higher aspect ratio but narrower chord the wing section was only going to be 75% of the depth (3/4" instead of 1").
To maintain adequate bending stiffness the balsa reinforcing was built into the skin rather rather than under it as before. In addition the wing was built in 3 pieces with a flat centre section to eliminate a joint at the highest stress point. Finally to retain a similar landing speed it had double hinged flaps.

Really skinny compared to the original!

The 55% wing mounted on the Wing Dragon fuselage with what I call my 'Court Jester' colour scheme!

Did it work? Well sort of!

With full flap the landing speed was no more than before but at the cost of a substantial trim change and in addition on full flap the aileron control was marginal in countering the motor torque.
The reduced wing area did not seem to allow it fly any faster so overall the complex (and rather delicate) double flap arrangement was of little benefit.
The wing stayed unused for nearly 2 years but was resurrected for this 'Push me Pull you' with counter rotating props which of course removed any torque issue. One flap full down for the camera!

Certainly lands slowly!

 

[quorneng]

With its Depron built wing and tail along with 3.7g micro servos even the 55% area wing had a pretty low wing loading so it really didn't need flaps anyway.
In addition for any sort of speed in a model the wing has to be thin, not the 11.7% of a standard Clark Y.
So I decided to build another but much thinner wing in Depron.
A tapered plan form similar to the 70% area wing but only half as thick at 6%, actually the same thickness as the Boeing B47!

To gain maximum spar depth the balsa flange was actually incorporated into the wing skin and was flush with the surface.

Clear tape was used to help reinforce the balsa/Depron skin joint.
The wing under construction. As it was going to flex rather more than my previous wings I built in a small degree of sweep back to ensure any bending under load would also reduce the incidence and so off-load the outer part of the wing.

This shows how much thinner the wing is compared to the previous standard Clark Y section.

The thin wing on the Wing Dragon fuselage.

It flew nicely and fast but it certainly flexed pulling much g. An outside loop deflected the wing to considerable negative dihedral which looked most alarming!
To give the wing a chance of a reasonable life a lighter airframe was needed so it was added to an all new, Depron fuselage, Wing Dragon look-alike.

To save further weight the wing was permanently fixed to the fuselage and the smaller 100W out runner carefully faired into the wing/fuselage joint along with a ducted spinner.

Whilst still retaining the same 1500mAh 3s as before this is by far the lightest of all my Wing Dragon size planes at just 12oz (340g).

With 120W/lb it has quite a sparkling performance and close to 10 minutes of full power endurance. Taken gently boredom tends to set in before the battery runs out!

 

[penerbang]

Fuselage plan?

I have wd sportster v2 too, and now fuselage is broken. And here in Indonesia I can not find that fuselage parts
Available. I will be happy if you share me your fuselage plan, so my wd will fly again.

 

[quorneng]

penerbang
I am amazed you have managed to destroy a WD fuselage. I have managed to break everything but the fuselage!
Building another will rather depend on the materials you have access to. My replacement fuselages were of the same basic proportions as the original but as a simple 'box' shape using 6mm Depron but you could do similar using balsa or even thin ply.
Even 6mm Depron is nothing like as tough as the original's polypropylene but it is strong enough and a great deal lighter.

 

[Timmy P]

Cool project.. How do you do the double hinged flaps.. Thats wild.. Just one servo on each side?

 

[penerbang]

penerbang
I am amazed you have managed to destroy a WD fuselage. I have managed to break everything but the fuselage!
Building another will rather depend on the materials you have access to. My replacement fuselages were of the same basic proportions as the original but as a simple 'box' shape using 6mm Depron but you could do similar using balsa or even thin ply.
Even 6mm Depron is nothing like as tough as the original's polypropylene but it is strong enough and a great deal lighter.

What do you think if I use coroplast to build fuselage?

Do you have any sketch for wd fuselage? I have no idea how I should build that fuselage, so it would be very helpful if you share your sketch for wd fuselage

 

[quorneng]

Penerbang
I am sure you can use coroplast as long as you have a good glue that sticks it together.

A sketch is a bit more difficult, however brought right down to its simplest form it can be just a flat sided box like this.

It only needs be wide enough for the battery and motor to fit in and the wing, motor and battery must be in the same relative positions as in the original. In addition the wing needs to be fixed on top so that it is at exactly same angle relative to the tail boom as it was on the original.

Obviously if you could add a rounded bits to the nose and the leading edge of the wing pylon it would help to reduce the drag.

You will notice on my version the construction was rather more complex with everything carefully streamlined.


But I was trying to create the most efficient lightweight airframe rather than for ultimate strength.

 

[quorneng]

Timmy P
The double flaps are worked from a single servo each side but with two links to different hole positions on the servo arm.

It took a bit of trial and error to get the flaps to move in exactly the right way but the resulting flaps are very effective.

 

[NORWAYFLIGHT]

Some 3 years ago I bought my first electric RC plane - an RTF Art-Tech 4ch Wing Dragon. Brushed 480 motor and a 1000mAh 9.6V NiMh.
View attachment 6991
Simple and robust (almost crude) with a modest performance and limited endurance but it 'did what it said on the box'! As I fly from a rough grass field it soon became a hand launch/belly lander.

To my mind the solid foam wing was unduly heavy for what it offered. I had intended to make a new built up balsa one but at about the same time I came across 3mm Depron sheet. 1/10 the weight of balsa, very easy to cut and glues well. What if I simply made the new wing in exactly the same way but in Depron?
View attachment 6992
Exactly the same span (40")and chord as the original, with a standard Clark Y section the wing was thick enough to need no reinforcement. The skin would carry all the load - I hoped!
The only balsa was the leading edge.
View attachment 6995
5g aileron servos built in to the wing structure with just the tip of the servo horn protruding. With the horn angled forward by 45 degrees to give a differential (more up than down) aileron movement to reduce aileron yaw.
View attachment 6993
It gives a very smooth bland surface.
View attachment 6994
The ailerons are top hinged with sellotape that makes a simple and flexible hinge.
The new wing complete.
View attachment 6998
The new wing weighed just half the weight of the original and was aerodynamically more efficient so it now could actually glide quite well.
With differential ailerons the rudder was not really required so more weight was saved by removing the servo and its linkage so it became a 3ch 'bank and yank'. Note the repaired RH wing resulting from a high speed crash.
View attachment 6996
The weakest point on the Wing Dragon is its low set tailplane so I made up a 'elevator only' V tail.
View attachment 6997
This also reduced the drag a touch as the tail surfaces were no longer directly in the prop wash.
It was now a nearly 4 ounces lighter so had a performance well beyond stock and could be looped and rolled with ease.

Next brushless and LiPo.

I plan on doing the same. And maybe even make the wing(s) slightly longer.

 

[quorneng]

NORWAYFLIGHT
The original Wing Dragon was 40" (1016 mm) span. This was later extended to 48" (1219 mm).
I have flown mine with a 60" (1524 mm) high aspect ratio Depron/balsa wing.

Flew fine but by keeping the same size tail meant its general handling suffered a bit so I judged the modest benefit in glide performance was not worth it.
The wing was later transferred to a significantly lighter (smaller motor) Depron fuselage powered glider.

No longer a Wing Dragon but it did glide well and could stay up longer than my concentration level!
This did lead me to explore just how long I could make a Wing Dragon sized plane fly under power but that is another story.

 

[quorneng]

I might as well complete the Wing Dragon(ish) story.
I did fit a 5000 mAh 2s into my Wing Dragon with a Depron full size wing to see how long it would fly.

Flying really slowly at minimum power it stayed up for 96 minutes.
Being so heavily throttle back the Emax 2812 and 7x4 prop was far from the optimum for cruising so it should be possible to fly for longer.
Although keeping the same overall size and layout a long series of tests finally resulted in a completely new all Depron air frame with a smaller lower kV 'Blue Wonder' motor driving an 8x4.7 prop. This prop is too big for the motor at full power but efficient for cruising power.

To eliminate the aileron horns and reduce drag the ailerons are directly glued to the servo arms. The servo itself acts as the inboard aileron hinge.
Even the Rx was changed from 2.4 to 35 meg as it has a significantly lower standing current.
In this form using a 1000 mAh 2s but ballasted to the size and weight of the 5000 mAh one it eventually flew for 63 minutes giving an average current usage of just under 1 Amp and that of course includes driving the radio and servos!
Using the 5000 mAh battery its endurance would thus be a just over 5 hours. This never been actually tested but I have flown it for 2 hours although it was me that gave up, not the battery!
It may be a rather specialised air frame but it is not that delicate as using full power (about 10A) it will readily loop and roll.

Remember it was doing all this with the big 5000 mAh 'endurance' battery on board.

An electric park flyer that can stay up as long as you are ever likely to want.

 

[Dante]

Where do you get your 3mm depron? Are you in the US? I'm looking to build 60% mighty minis using the h pack but I can't find depron that is under the price of a private jet in the States.

 

[quorneng]

I am in the UK and even here true Depron is now very hard to get hold and is the softer more flexible type. I fear the two sheets I have will be my last.

 

[quorneng]

My final version of the Wing Dragon formula was scaled up by 50% to 60" span.
Using a Depron/balsa tapered wing and a bigger 350W motor driving a 10x4.7 prop with a 3000 mAh 3s.

At only 28 oz all up with over 400W available it had a huge power reserve and with a considerable cruising endurance of close to an hour. It could glide and thermal too!
This is the sort of thing it was good at.