Super AVA Pro

[yeow_hwee]

I recently had the chance to build and fly a Super AVA pro 3.7m glider.

It was an awesome experience, its has a 3.7m wingspan, flying weight of around 1700grams, RES control.

RCS brought it in for me to save the headaches of shipping. It cost around S$2K but varies according to the exchange rate, check with ken for the exact pricing now. I used this plane as part of a platform for my FYP project. I was looking for a thermal glider with very low wing loading and good stability. After considering many other gliders, I decided on this plane due to its strong following in RC groups.


The plane comes in ARF and for the price paid for it, I expected alot more work to be done. I wouldnt suggest this plane for a complete beginner as it takes some modelling skills to build it up.

Let me list the bad points first. For a 2K plane, I had to cut the vertical stabilizer's covering in order to fit the servos inside before resealing it which i was very hesistant in doing it but there was no other choice.
The fitting of the spoiler servos was a huge pain in the ass. (but then later i discovered this plane is better flown Without spoilers)
The carbon boom had to be cut in order to fit it to the fuselage. The fuselage didnt have much place to play around with the placing of the electronics. It was very very lucky on my part that i didnt do any CG balancing before cutting the boom and still got the CG roughly correct at the exact spot.
Fitting of outer wing panels was not exact and i had to file away some good to get it to fit properly.
The outer wing panels was intended to be held in place by friction ! which was quite crazy, so i added my own fibertape which had to be removed and replaced after every flying session.
For someone used to flying a 1.5m plane, I was wondering why this 3.7m plane felt so sluggish in turning.

OK, here are the good points.
ITS A DREAM TO FLY. I remember years ago I flew a very light hand launch glider called kyosho swing, this was like a monster version of it. Very easily controlled with just rudder and elevator, great floating capability. Very easy to slow it down to near stalling speed when landing. No tip stalling tendencies whatsoever. It takes practically no effort to thermal it, just climb to a decent altitude and cut motor, it signals thermals perfectly. It can be easily trimmed to be flown hands off with little input by the pilot.

[yeow_hwee]

As seen in the pictures, I added thin film solar cells onto the wings of the plane. Those solar cells were bought from jethobby. Advantages are that there are very thin and flexible so it easily conforms to the airfoil. Weight is approx 6 grams. BUT the efficiency is down the drain.

If i had to redo this project again, i would have gone with silicon solar cells encapsulated with a flexible material which would have better efficiency.

The estimated flying weight of this plane listed online was 1600grams but mine weigh in at 1800 grams and I still felt more weight could be added to improve the handling in stronger wind conditions. Maybe the weight could go up to around 2000grams with no adverse degrade in performance. Considering the 3.7m wingspan, 2000grams is till quite respectable.

Apologies for the incoherent report, I am just typing whatever that comes into my head at the moment.

It definitely needs a big area to fly, at least 1 football field. If you are a decent pilot and winds are not too strong, I usually fly small circles when landing to drain off all the airspeed and straighten the plane at the last moment so i do not need much runway space. Spoilers are not necessary in my opinion.

At high altitudes, this plane is still very visible and striking against the sky.

[randomtask]

Nice report and a beautiful plane you have there. Hope to see it flying "live".

A method i use to really slow down a plane without using flaps/spoilers is by pushing hard down elevator then pulling up hard again. Then push the nose down again a bit so that it won't stall. I practiced this when a bit higher until i got confident.

Cheers,
Adnan

[chiadennis]

HI Yeow Hwee
Beautiful glider.
AVA was one of my consideration when I looking around for a 4m glider. I am not really a fan of RES so I put at the back of my mind. The other that I consider is the Pulsar 3.7m. Here some review on AVA and Pulsar. http://sites.google.com/site/f5jport...elos/super-ava

At the end of the day, I manage to persuade my dear buddy to give up his Thermik. Thermik is a 4m beau and if you see my mini build thread you see how it fit into my house. http://www.daddyhobby.com/forum/showthread.php?t=54298

I hope to get my thermik flying soon and maybe we can meet up to catch some thermal.

BTW
What with the solar panels?

[edmond22]

Interesting project Yeow Hwee, Subscribed.

[yeow_hwee]

The wings break down into 3 pieces : 2 outer wing panels and the middle wing section. A huge problem of flying such big planes is transportation. Even when broken down, the wing bag is unable to fit inside the boot or backseat of a sedan car. We had to lower the back seat so the wing bag stretches from the front passenger seat all the way to the boot.

But surprisingly, it is easier to transport it by mrt + bus.

As this is a project from my school, it was returned to the school's lab after the whole project. *super heart pain* I spent quite alot of time going through the minor details and building it up. Right now it is sitting beautifully in the UAV lab of NTU Aerospace hangar. I hope the next person who takes over my project better be a rc pilot, saw too many crashed planes in the hangar already. Its an experience of a lifetime to be able to fly such a plane.

For those interested, I used this plane as a remotely piloted aerial vehicle. The first phrase is to incorporate the solar cells to extend the flight time (5 hours), Yellowjacket PRO camera tx and rx was fitted to have FPV of the plane flying. We had another group doing the micropilot system for autonomous flying, combining everything would be the next phrase i supposed. The down side of using the super ava pro is that its a very very tight squeeze in the fuselage and some components had to be placed outside the fuse, disrupting the aerodynamics.

For those interested in my propulsion, I went with a Hacker BL motor, A20-22L ( i think so, the 900++KV one), combined with a 23 inch folding prop, I had around 500-600 grams of thrust ONLY for a 1800 grams plane. The climb rate was nothing fantastic but it could climb lar. There wasnt any power to fight huge winds of course but the whole idea was to get up there and turn off the motor to start finding thermals, thats where it really excels. For more recreational flying, I would suggest a much more powerful setup, maybe something with around 1200-1800grams of thrust.

My job is done already, I just graduated from NTU Aerospace. This was one of my best time in uni, doing something i like and flying it while the rest of my peers was complaining about the FYP Very grateful to my prof and the uni for allocating me this project.

[chiadennis]

Well Done!
On the motor, are you using geared? I don't think 924kv can spin such a big prop. May stress the motor on direct drive.

Anyway well done and congrat on you graduation.

[yeow_hwee]

no lar, direct will burn up the motor.

I am using a kontronik 5.2:1 gearbox to gear down the rpm. Big prop + low rpm = higher efficiency.

My amp draw is only around 7-8Amps max.

[Sunstorm]

Please share a bit on the power systems and the charging of onboard batteries using the solar panels?

Very interesting project, hope to see something like this have practical uses in Singapore and elsewhere....

Congrats on the graduation!

[Kantankerous]

Pity I can't get to see the super Ava fly But well now! Congrats Yeow Hwee!

[yeow_hwee]

I link the solar cells together in parallel and series to acheive an output voltage of 19+V in bright sunlight.

Using a homemade voltage regulator, it is step down to a constant 12+V at all time. This is then linked to a cheap Esky Charger which constantly charges the battery at 750mAh.

The downside of this schemetic is that my solar cells produce way more power than the charger can handle so there is alot of wastage. It wasnt easy to find a charger able to be portable enough to fit into the fuselage and have a charge current of more than 1000mAh.

The upside is that everything is pretty simple and cheap. Esky charger is really cheap and the electronics for the voltage regulator was just couple of cents.

If next time the cells are changed to silicon encapsulated cells, the charger and voltage regulator will have to be changed.

I would say that the concept for such a project wasnt too hard. Its more of integrating the current technologies together to get the desired end product. I believe there are solar powered UAVs that have achieved flights of more than 7 hours WITHOUT backup battery. Theoritically, UAVs will be able to achieve unlimited duration of flight time given a suitable energy storage medium and solar cells.

[yeow_hwee]

I'm afraid I cant add in the whole chunk of my report here.

Another concept that I was looking at is an autonomous thermalling vehicle. Basically gyros are attached to the plane and link to a computer in such a way to mimic thermal pilots' reaction to the plane when it hit thermals. The amount of turning to core the thermal and stuff will be programmed inside. Unlike solar power, thermals are avail 24 hours so long there is a temperature difference. Next person doing FYP can steal this idea for free !!! lol

Btw, just to check, anyone from NTU engineering here ? undergrad. I really hate to pass over my plane to a non-aeromodelling person, confirm crash one. If you are studying in ntu 3rd year mech or aerospace engineering and want to fly the plane for fyp, please do contact me and i'll arrange something for you.

[randomtask]

Another concept that I was looking at is an autonomous thermalling vehicle. Basically gyros are attached to the plane and link to a computer in such a way to mimic thermal pilots' reaction to the plane when it hit thermals. The amount of turning to core the thermal and stuff will be programmed inside.

That is a very cool idea. Pun intended

Cheers,
Adnan

[joe yap]

Good to know that there is actually a Supra flying here. I'm curious to actually see one flying. You need to have a deep pocket to own one though.

[foxkilo]

I link the solar cells together in parallel and series to acheive an output voltage of 19+V in bright sunlight.

Using a homemade voltage regulator, it is step down to a constant 12+V at all time. This is then linked to a cheap Esky Charger which constantly charges the battery at 750mAh.

...

Hi,

Interesting project. Problem with the flexible solar cells is that they generate too little current (100mA per piece?) so can only be used to charge the onboard battery.

Did you connect the battery to both the charger and to ESC at the same time? (i.e. charging and discharging at the same time?) Or was there some intelligent circuit to switch between the two, and not do both simultaneously?