Well, after a lot of thought, I decided to do away with the cub trainer that I had built and start afresh. Reason was that I had some basic design issues - a) the original design was not for 1KG+ model and b) I was not comfortable handlaunching the bird.

So now, the new trainer was started post Christmas. I decided against posting till I maidened it.

The specs are as follows
1) Construction material - a combination of 3mm coro and 5mm compressed themocol (biofoam)
2) Power system- Motor from rcforall 2820/6 - Turnigy 3s1p 3000mAH, Towerpro 40A ESC and 10x5 prop
3) Wingspan 53 inch - semi semetrical
4) Chord - approx 9.4 inch
5) Fuse length - approx 38 inch and about 2inch thick (for handlaunch)
6) 4 servos with flaperon programming.
7) All up weight (unfinished) 1260 gm. Provision for another 80-90 gm for finishing
CG approx 30-33% from LE

So yesterday, on a chilly Delhi winter afternoon (temp around 9 C with slight fog) I thought about maidening the trainer. Idea was to do a simple test to take it up and then see the glide pattern when throttle is cut. Essentially to see how it glides with power cutoff.

Along with a friend of mine went to a local park. It was deserted. Turned on the power at approx 50% throttle the bird was ready to fly off. My friend launched it directly into the wind and up in went. First time I was actually flying RC (previous attempts were not good). Then the plane banked slightly towards the left and I did not even attempt to correct it. At around 20 feet, I cut power and the model glided downwards, but again the gradient was sharp but not too steep. I was so engrossed watching just the plane that I forgot about my surroundings - suddenly I realised that the bird was just about 5 feet from the bushes... not much could be done as the wings went right into the bush. 

Nothing major, just the wing mount was damaged and a few hinges had come off. However, essentially I realized that I need a bigger place to fly but more importantly this one actually flies. Its a great feeling and I am sure many of you guys must know how i feel.


Pankaj

congrats man! i know the  feeling,when u see the bird that u built fly !

so any pics.?

Hey

Congrats Pankaj....waiting for the pics and a video too 

Murphy should have left some of his laws for R/C flyers as well. The first should have been - "The smallest plane you have would outrun the biggest park you can find"
I am myself struggling to find an alternative place to Jakkur (BLR) whose member ship I am awaiting! I have a 30" modified high winger and I don't want to fly it into the road next to the football field I have been eying on. That reminds me , where Dilli waalas are flying ? Being a metro, I guess it doesn't have the luxury of sharing the tarmac with Airports/Glider Clubs or a dedicated club field like Chennai guy enjoy

So what plan you are looking for ? why don't you try building from Balsa kits when you are so passionate for scratch build ? Try the local Delhi LHS or people like Sanjeev of RCDhamaka - they may  get them for you (though Kits are rarer than ARF)

When you are already into Coro, its combo with Balsa Spars would be a killer!! With over a week into my first 'Depron' Clone Bio Foam F-22 scratch build, I guess foam is far too delicate thing to work on...

Quote from: ujjwaana on January 18, 2010, 07:13:50 PM

So what plan you are looking for ? why don't you try building from Balsa kits when you are so passionate for scratch build ? Try the local Delhi LHS or people like Sanjeev of RCDhamaka - they may  get them for you (though Kits are rarer than ARF)

When you are already into Coro, its combo with Balsa Spars would be a killer!! With over a week into my first 'Depron' Clone Bio Foam F-22 scratch build, I guess foam is far too delicate thing to work on...

Well, with limited RC skills and no trainer in sight, I was not sure how I would fare and so needed to lower the cost of learning. Remember even an entry level ARF (apart from Mr. MOSS ), costs around 4K upwards, whereas you can possibly build quite a few scratch builds in that amount. I plan to go in for an ARF/Kit once I have some sense of control in RC flying.

As you have figured out, foam is delicate and hence it would need reinforcements. That was one of the main reason of using coro - as reinforcements. Alternate idea is to use 2" wide masking tape. A few layers of this on the surface would be able to take quite a few hits.

Pankaj

Quote from: PankajC on January 19, 2010, 10:46:34 AM
As you have figured out, foam is delicate and hence it would need reinforcements. That was one of the main reason of using coro - as reinforcements. Alternate idea is to use 2" wide masking tape. A few layers of this on the surface would be able to take quite a few hits.

Reinforcement should not be an issue. The master SPAD/scratch builders here all use simple materials like bicycle wheel spokes to kebab sticks for structural reinforcement, and tape (as you said) for surface reinforcement.

Building is a very cost effective way of "trying out" your initial flying skills.  With a "prop-saver" setup, going this route should take care of the initial crash issues.

Quote from: anwar on January 19, 2010, 01:00:01 PM
Building is a very cost effective way of "trying out" your initial flying skills.  With a "prop-saver" setup, going this route should take care of the initial crash issues.

That brings up another question.  Most of the plans we see are either pusher jets or acrobatic/3D low/mid wing models.  Other than the Blue Baby which has been mentioned before, has anyone built a high-wing beginner friendly foamy ?

Well.... another day .. another attempt and another crash....
Man learning without a instructor is proving quite a bother....

I managed to find a large field nearby and got ready to fly. The all up weight close to 1380gm with 53" x 9.4" wingspan. The wind was stiff. Launched into the air at half throttle, the model shot off straight (Sai your 2820/6 is real real power house). Gave a slight jerk on the elevator and it just shot off vertically into the air like a fighter craft. Around 60-70 feet up in the air, I leveled it - so far so good.
First mistake, forgot to lessen the throttle - a beginner should fly just a little bit more than the stall speed. It is difficult to control a model that is running like a cheetah on steroids.
Second mistake - before getting used to the model, applied aileron. The model banked sharply with nose coming down, somehow managed to correct the turn.

3rd mistake - without leveling the plane, with the nose still pointing applied rudder.


I have been practicing on sim, but as a newbie experience, this is just a video game. The flying part is totally a different experience altogether. That was the last of it. The model turned too steep and came down hard on the ground almost at a 70degree angle. The impact was HUGE..... Prop broke, the wings sustained major damage, but the most damage was on the fuse. The firewall was about 9 inch from the wings LE. This part had two layers of coro and then covered with foam. The battery itself was encased within the coro with layers of biofoam and EPsheet The entire nose is smashed to bits, the battery is ripped open and bent.... seems that the motor and the esc are OK.... The rest of the fuse did not suffer any damage at all....


So what are the lessons...
1) need a smaller plane
2) need a slower plane

However, with no one known who could show me the ropes of RC, this is going to be one tough ride of build - fly - crash - build again cycle.....

Pankaj

1 photo = thousand words.

Next time please carry a camera pankaj sir

Good to know that the model flew well , but basically a pilot error. So which sim have you been practicing on?
Also at such a major impact there are chances of the motor shaft getting bent, inspect that as well, coz a very little bend can cause huge vibration. Hope the motor is safe. ALso is the battery reusable? I read that charging damaged/bent battery is not a good idea

Next time select a smaller pitch prop.

Quote from: vinay on February 07, 2010, 10:57:26 PM
1 photo = thousand words.
Next time please carry a camera pankaj sir

Yep... missing those pictures big time

Ok, some construction images of the fuse.

Some fuse construction images.....

more

After the crash.......

more...

Beautiful build

Looks like you can charge the lipo, though be careful and use a lipo bag.

Thanks, Vinay.
Incidentally that has been my grudge. I do spend a lot of time building, but in absence of local mentor, it just seems a waste of time as I end up crashing. Mind you, the models fly well, but I just do not have requisite skills yet to take care...

BTW, the finished fuse that you see is AFTER the crash. The front part got bashed up but the tail remained intact . Also, the gap in the fuse, next to the trailing edge of the wing is where I house my Rx. The gap allows me to plugin/remove the flaperon plugs

Pankaj

Pankaj - You should focus your energy in building a foam one that is preferably a pusher one. Make it in such  a way that it can pretty much glide when throttle is cut.  Make it in such a size that you have some weight left to be added on later, if and when you crash (you fix it with something like X ray films and epoxy, but the added weight of those should still be manageable with the existing power system).

The model from Ashta should be a good inspiration

Anwar,
This one also glides perfectly when power is cut, the point was that I forgot to cut power as it came down quickly. Hence the crash...

What I was referring to was that as a newbie, it takes some time to adjust to the eye-hand-mind coordination  
Now matter what you do, at the end of the day, your mind knows that SIM is just a game, so it is no big deal if you crash. However, when flying for real, you have so much of adrenalin being pumped in it becomes very difficult get a grip on your responses.
This is where a mentor would probably come in handy. Else for guys like me it would be baptism by fire.

While yes, I could go in for a pusher setup, but if your model comes in at rocket speed its not much of a help either

Pankaj

If you forget to reduce throttle on the way down, that is a tough situation to be in.  You can get significant help if you locate fields with lots of slightly taller plants (paddy fields, wheat fields etc).

Obviously, more and more sim time helps.

Usage of good sim like G4.5 really helps, they not only simulate orientation but also physics/winds/thermals almost naturally. G4.5 rocks.

Guys, I am been doing all that. I have also simulated wind speed, direction and turbulence. But still when I land up in the field, it is a totally different experience. I do believe, any newbie would be in similar position.
I think Sims would help once you get the basic flying skills in place

You may be right, I never flew a plane, plan to build one shortly. However my Heli experience was very close to the sim. , W/o sim experience , I wouldn't have dared to maiden it.

Sim and the real thing are two different feelings ("the fear factor"!), but if you have set goals for yourself on the sim, and are able to land a plane exactly where you want time and again, then your chances for crashes with the real thing are greatly minimized.  I have seen the difference time and again with newcomers.

In fact, when anyone comes to start in the hobby on our field (the tend to contact us through our other forum http://www.rcqatar.com), we ask them to buy a radio and a sim (or loan them a sim), help them set it up, and ask them to practice for couple of weeks.  When they come back after couple of weeks on the sim, they can pretty much fly on their own, but we still put them on a buddy cable for the first few flights.  A place with enough tall grass/plants OR a model like the EasyStar/HawkEye/AXN-Floater can completely replace the buddy cable part.

Quote from: anwar on February 09, 2010, 08:58:35 AM
Sim and the real thing are two different feelings ("the fear factor"!), but if you have set goals for yourself on the sim, and are able to land a plane exactly where you want time and again, then your chances for crashes with the real thing are greatly minimized.  I have seen the difference time and again with newcomers.

seems that I am the odd man out. I can easily land from electric to jets on a sim, but am having all these difficulties on the field.