My first foam plane.

[quorneng]

I am sure like many aero modelling had to take a back seat to my career and family although 'building things' did return when my eldest expressed an interest in Lego and guess who took it to an extreme.
As the career wound down and I could afford it I decided to try an modern electric RC RTF a humble Artech Wing Dragon Sport. First released in 2000? but by then (2009) it was decidedly 'old hat' and as result it was 'on offer' . Old habits die hard!

A brushed 540 with 9.6V 1000 mAh NiMh battery on 35 mHz but it did fly well enough and was modestly aerobatic although each flight was not very long.
To my mind it was pretty crude.
'Foam' aileron hinges which meant its four 9g servos had to work quite hard to simply deflect the control surface. The long metal control rods for the rudder and elevator weighed nearly as much as the servo moving them and a 'floppy' set of tail feathers.
The solid foam wing felt rather heavy and with just a short dihedral brace it was not a particularly good structural use of the foam material.
The cheap Tx and Rx supplied did work pretty well but by far the best bits were the nearly indestructible polypropylene blow moulded fuselage and the glass fibre tail boom.
Within a few months of the Wing Dragon I bough my first sheet of 3 mm Depron which set me wondering, how much lighter might a direct replacement wing be but built hollow and in Depron.
Built in a conventional style with ribs. Depron sheet is quite strong, particularly in tension, so no spar as such just a shear web at the maximum wing thickness. All the loads to be carried by the wing skin, or in other words a true monocoque construction.

With very free moving top tape hinges much smaller and lighter servo could be used.

The end result gave a remarkably bland and smooth finish for just half the weight and it certainly felt plenty strong and rigid enough.

Shaving off 2 oz (50g) off the all up weight along with improved wing aerodynamics made a startling difference to the performance.

Loops and rolls could be performed at any time and it could now 'cruise about' at reduced throttle for twice as long as before.
Then came 'brushless and LiPo' but that is another story.

It is still flying 10 years on. Guess which bits are still original Wing Dragon!

 

[quorneng]

Perhaps I should complete this story although technically it is still going on.
The great improvement in performance using the built up 3 mm Depron wing was more than matched by the change to LiPo and brushless.
I selected an Timex 2812 1500 kV motor as it seemed to have similar power to the 480 'race' brushed (It had replaced the worn out 540) and it was only 1/3 the weight.

The lower weight suggested it would need a lighter battery to maintain the CofG so a 1500 mAh 3s LiPo was selected.
Overall this combination gave 50% more capacity and shaved a further 5 oz (114 g) off the already lightened 25 oz (680 g) Wing Dragon.
Performance was greatly improved.
The next items were the 9g servos, the servo tray, the long metal push rods & the flimsy tail feathers.
3 mm sheet Depron with a balsa leading and trailing edge were quite as stiff and a bit lighter than the original plastic ones. I had already set up the ailerons in the Depron wing to have a differential action which virtually removed the need for a rudder so it could be flown 'bank and yank' with just an elevator servo.

By placing the servo in the tail with just a short link rod to the elevator horn a much smaller 3.7g servo was perfectly adequate.

The servo wire and the rx aerial both ran inside the boom to keep clear of the prop.
The net result meant a further ounce was saved. Removing the undercarriage (no loss as I fly from a rough grass field) saved a bit more weight and improved the aerodynamics further. The ready to go weight was now just 18 oz (510 g). Vigorous aerobatics and flights of 30 minutes were now quite possible.
With so much weight removed I felt the wing area was actually more than required so keeping the same span but tapering the wing to reduce the area to 70% would not only allow it to fly faster and handle wind better but would also provide a better structural solution.
Just for fun I added flaps as well.

The final variation, and how it has been for the last 5 years, was to change to a V tail.

Such a tail works well with a grass belly lander and by keeping all the tail surfaces out of the direct prop wash actually improves the performance just a bit too.
The single servo 'buried' in the root of the left hand tail plane works both elevators.
The V tail and smaller wing are lighter than before so exactly compensates for the two extra servos required to work the flaps. It thus still only weighs 18 oz (510 g).
A short edited video of it doing it stuff in 2015.

It can and still does!

 

[ScottyWarpNine]

Nice job with the resto mod!

Not sure I've ever seen someone make a fairing for the motor's rotor. Any issues with vibration or cooling?

 

[Monte.C]

Perhaps I should complete this story although technically it is still going on.
The great improvement in performance using the built up 3 mm Depron wing was more than matched by the change to LiPo and brushless.
I selected an Timex 2812 1500 kV motor as it seemed to have similar power to the 480 'race' brushed (It had replaced the worn out 540) and it was only 1/3 the weight.
View attachment 185911

View attachment 185915
The lower weight suggested it would need a lighter battery to maintain the CofG so a 1500 mAh 3s LiPo was selected.
Overall this combination gave 50% more capacity and shaved a further 5 oz (114 g) off the already lightened 25 oz (680 g) Wing Dragon.
Performance was greatly improved.
The next items were the 9g servos, the servo tray, the long metal push rods & the flimsy tail feathers.
3 mm sheet Depron with a balsa leading and trailing edge were quite as stiff and a bit lighter than the original plastic ones. I had already set up the ailerons in the Depron wing to have a differential action which virtually removed the need for a rudder so it could be flown 'bank and yank' with just an elevator servo.
View attachment 185916
By placing the servo in the tail with just a short link rod to the elevator horn a much smaller 3.7g servo was perfectly adequate.
View attachment 185917
The servo wire and the rx aerial both ran inside the boom to keep clear of the prop.
The net result meant a further ounce was saved. Removing the undercarriage (no loss as I fly from a rough grass field) saved a bit more weight and improved the aerodynamics further. The ready to go weight was now just 18 oz (510 g). Vigorous aerobatics and flights of 30 minutes were now quite possible.
With so much weight removed I felt the wing area was actually more than required so keeping the same span but tapering the wing to reduce the area to 70% would not only allow it to fly faster and handle wind better but would also provide a better structural solution.
Just for fun I added flaps as well.
View attachment 185920
The final variation, and how it has been for the last 5 years, was to change to a V tail.
View attachment 185921
Such a tail works well with a grass belly lander and by keeping all the tail surfaces out of the direct prop wash actually improves the performance just a bit too.
The single servo 'buried' in the root of the left hand tail plane works both elevators.
The V tail and smaller wing are lighter than before so exactly compensates for the two extra servos required to work the flaps. It thus still only weighs 18 oz (510 g).
A short edited video of it doing it stuff in 2015.

It can and still does!

Wow look at that old motor. Reminds me of what we were using 30 years ago!

 

[quorneng]

ScottyWarpNine
The fairing was made of Depron so weighed just a fraction of a gram so balance no problem although I doubt it made any discernible difference. It had a hollow centre it still let cooling air out not that there was much anyway as it requires very little power to fly. The outer surface of the bell was also in the full airspeed airflow so added significantly to the cooling.
Monte.C
Nothing wrong with that style of motor if you are after electrical efficiency rather than absolute power.

The final chapter was when I wondered how long it could fly if I put in a big battery? Like a 5000 mAh 2s.

Along with a light weight (no flaps) wing of the same span as the original Wing Dragon wing.

The answer was a very boring 90 minutes, power on the whole time.
This posed the question if I kept to the same formula and convenient size but started again from scratch and optimised everything for endurance how much longer would be possible.

 

[Thomas B]

I thought I would post about my first foam RC plane for a different perspective. I had posted this earlier somewhere around here, but added more detail here.

I started flying RC in about 1970. In 1975, I decided to try electric, which was NOT common then. I procured a Carl Goldberg Ranger 42 injection molded polystyrene foam kit, designed for .049-.09 glow power. Astro Flight Incorporated had been in business for a while and I obtained one of their Astro 05 ferrite can motors, which came with a NiCad battery pack. I had an EK Logictrol Little Red Brick radio system, where the RX and two servos were all on one brick. Installed with four screws.
Prop was a Cox gray 6-3 or perhaps 6x4. No ESC, no servo controlled in off switch.

Someone had found out that the molded foam area for the glow motor was a perfect friction fit for the 05 can motor. Assemble rest of aircraft, add prop, install the radio brick and pushrods and landing gear and it was done in one long evening. There was a toggle switch to turn the motor on.

The little Ranger 42 would take off our paved runway, with a long run, probably 150 feet. It had a slow but steady climb. It would loop and do a rudder roll from a shallow dive. With no rc switch or ESC (no ESC available then), you flew the aircraft until the Nicad pack ran almost out, and you would have to land the airplane under a very small amount of power.

This was the first successful electric RC aircraft at our large RC club in Fort Worth.
Flew this for one season, then transferred the motor to a sailplane for another season. After that, gave the AFI 05 motor system to by brother, who used it from many years on his little RC Dumas Swamp Buggy.

My next electric model was in 1987 and was a plans built model called a Low Voltage, powered with the mighty Astro Flight 035 Colbalt on 6 800 Mah Nicad cells. About then, Futaba came out with a radio system with a brushed ESC built into the RX and I used that. Handy. Flew this model for 8-10 years and it was usually the only electric model at the field and at events I went to.

We have come a very long way!

 

[quorneng]

The story continues
Eventually after 5+ years of flying and sometimes landing heavily the Depron wing with flaps eventually got damaged beyond redemption.

At the time (late 2021) I was building some lightweight EDFs out of 5 mm XPS foam actually laminate underlay. Rather soft & flexible but easy to cut. I had been given 20 sheets (30" x 18") for free!
So could I build a replacement wing for the Wing Dragon using my original simple top and bottom skins and a shear web all in XPS with no reinforcing of any sort, like this.

Very simple. Each wing half is made up of just 4 pieces.
The wing has the same 1110 mm (43") span and has a 2:1 root to tip taper as before.
The ailerons are cut out after the glue is dry.

The leading edge of the aileron is cut back to 30 degrees.
The aileron servo is 'let in' through the underside and glued directly to the underside of the top surface. The lower skin cut is reused, sanded as appropriate and glued back in.

As the wing has no ribs no problem feeding the servo wire through.

The wing was painted acrylic blue overall so it is now a "Blue Dragon".
The 3.7 g servo was salvaged from the broken wing and has a simple direct link made from an easy to bend paper clip!

Jan 2022. The completed XPS wing on the old fuselage and V tail, also painted a matching blue.

At 368 g (13 oz) with its 1500 mAh 3s and a Emax 2812 1500kV it is exactly half the weight of the original NiCd/brushed Wing Dragon Sport and it uses the same size 7x6 prop!
Its performance and endurance however is definitely not the same, in fact it now has the climb and glide capability of a half way decent powered glider!
I am a keen follower of the Colin Chapman (Lotus) philosophy "To improve performance add lightness"!

 

[SSgt Duramax]

The story continues
Eventually after 5+ years of flying and sometimes landing heavily the Depron wing with flaps eventually got damaged beyond redemption.
View attachment 216373
At the time (late 2021) I was building some lightweight EDFs out of 5 mm XPS foam actually laminate underlay. Rather soft & flexible but easy to cut. I had been given 20 sheets (30" x 18") for free!
So could I build a replacement wing for the Wing Dragon using my original simple top and bottom skins and a shear web all in XPS with no reinforcing of any sort, like this.
View attachment 216368
Very simple. Each wing half is made up of just 4 pieces.
The wing has the same 1110 mm (43") span and has a 2:1 root to tip taper as before.
The ailerons are cut out after the glue is dry.
View attachment 216369
The leading edge of the aileron is cut back to 30 degrees.
The aileron servo is 'let in' through the underside and glued directly to the underside of the top surface. The lower skin cut is reused, sanded as appropriate and glued back in.
View attachment 216370
As the wing has no ribs no problem feeding the servo wire through.
View attachment 216369
The wing was painted acrylic blue overall so it is now a "Blue Dragon".
The 3.7 g servo was salvaged from the broken wing and has a simple direct link made from an easy to bend paper clip!
View attachment 216371
Jan 2022. The completed XPS wing on the old fuselage and V tail, also painted a matching blue.
View attachment 216372
At 368 g (13 oz) with its 1500 mAh 3s and a Emax 2812 1500kV it is exactly half the weight of the original NiCd/brushed Wing Dragon Sport and it uses the same size 7x6 prop!
Its performance and endurance however is definitely not the same, in fact it now has the climb and glide capability of a half way decent powered glider!
I am a keen follower of the Colin Chapman (Lotus) philosophy "To improve performance add lightness"!

Ha! That was the saying in the miata world to. Only so much weight you can strip from those before they become a tin can.

I was wondering about that underlayment stuff. I saw it by the roll at the flooring store.

 

[quorneng]

SSgt Duramax
Its not the roll stuff but rigid sheets. The ones I use are 19.5" x 47" x 3/16" thick in grey or green.
Being expanded polystyrene you must use a proper foam safe glue to stick bits together.