Deleted. info included above. Sorry

Your points are well taken . Why no other entries so far (other than Karthik & Hitesh ) I think everyone is waiting for more offers from Glidiator & Freeflight Or is it that everyone is waiting for the final day ?

Indoors with a gentle catapult.

Perfect flight with a nil height loss, straight.  Distance covered about 20ft.

Lunchbox Glide test outdoors.

Winds almost nil.  

My Chuck glider formed more or less a parabolic flight path with a hand launch.  It tracked straight. Climb seemed to be normal.  After top of climb, the half of descent seems to be little fast but last half was like a meteor falling off in starry starry night.  Distance covered about 60 ft.

Unable to attach the video as file size is large.

Dreamliner:

"Indoors with a gentle catapult.

Perfect flight with a nil height loss, straight.  Distance covered about 20ft." Wonderful must be a good sight

Lunchbox Glide test outdoors.

Winds almost nil.  Good.

"My Chuck glider formed more or less a parabolic flight path with a hand launch.  It tracked straight on yaw. Climb seemed to be normal.  After top of climb, the half of descent seems to be little fast but last half was like a meteor falling off in starry starry night.  Distance covered about 60 ft." I do not understand when you say tracked straight on "yaw" . Generally speaking yaw means to have a gentle turn. So did it fly smooth with a gentle left turn?

When you say "top of climb, the half descent seems a little fast... " That to me it means you have a gentle stall. If I have understood it correctly, put a little clay ( always very small and repeat as needed) till you get a very slight nose-up and smooth glide. Let us all know.

Sorry for the mix-up.  It tracked straight on outdoor glide test.

Upto, 40 feet, the climb angle was normal.  After that, It started nose diving from top climb which became steeper with descent.

Thanks for your feedback, will try different approach again as suggested by you.

"After that, It started nose diving from top climb which became steeper with descent."

That description is of a classic stall. The glider went up, the wing no longer generated lift, so it came down fast trying to regain flight but the ground was very close, looks like dive.

Looking forward to your flights in experiments.

Regarding CG :

Dear all : always start testing at the CG shown on the plan. But that was the designers glider. Your correct CG maybe a a couple mm forwards or backwards. In the lunchbox that I lost, my CG was 1.5 mm behind the the one shown on plan. It took a backward CG for MY glider to fly slow with just a hint of stall, nose very slightly up during entire glide phase while circling to the left.

So do not worry so much of adding weight to cure stall, make it glide well.

For some time this thread was on first or second place, on the homepage, due to the interaction regarding "Lunchbox".

I personally kept on checking this thread for new updates and more guidance.

Same here. Me too, . Looking forward to all your videos.

Quote from: WeekendFlyer on December 06, 2020, 09:20:33 PM
For some time this thread was on first or second place, on the homepage, due to the interaction regarding "Lunchbox".

I personally kept on checking this thread for new updates and more guidance.

एस ,  all of us were waiting for your updates and videos . Did you try all the corrections @Freeflight suggested ? Results ?

I'm quiet.
But I'm watching!

Quote from: SI74 on December 06, 2020, 11:07:50 PM

Quote from: WeekendFlyer on December 06, 2020, 09:20:33 PM
For some time this thread was on first or second place, on the homepage, due to the interaction regarding "Lunchbox".

I personally kept on checking this thread for new updates and more guidance.

एस ,  all of us were waiting for your updates and videos . Did you try all the corrections @Freeflight suggested ? Results ?

Got free from some personal work, now will give time to this contest.
I haven't tested yet, but will be doing in a couple of days. 

Watch out

Just a couple more points to share:

1) when trimming the glider, always pick no wind days, in the evenings. Mornings are good too, but the dew on the ground is not good for your glider. Now that your glider is ready, try to fly between 10 AM  and 1 PM. these are the times that thermals are produced and should give you extra flight times.

2) When you pick up your glider after the flight, always try and a) pick it up from the nose just behind the clay. You pick it up from say wing, stab or even worse rudder, you have a good chance of affecting your trims. b) always pick up the plane yourself and walk back to fly again from the same place you launched before.

Really eager to see your flight videos.

One more glider trimming and flying video by the expert. Very well made video.
He talks about stab tilt by bending the fuse (same as Glidiator talked above), left rudder etc. Notice how hard he launches for the glide test ( slow push glide test is not representative of the actual glide speeds). I recommend you watch this about 8 minute video as he encapsulates all the major points that I have discussed above.You will gain a lot of knowledge from it. Enjoy.

Very nice, despite getting banked at launch.

A very slight reduction of nose weight (say 2 pinheads of plasticine), a touch of left rudder, and it's ready for the catapult.

Beautiful. For the first catapult launch, fly as it is. Looking forward to seeing everyone's videos !!!

No update. Where are you guys?

Weekendflyer
Rooster
Aspersid
Prabal276
Karthick Ashwath
Alex Bessie
Girish Madhavan

No update from even Glidiator!
Come on Sir. You're one of the motivators...

Congratulations Hitesh. a job well done. Your glide is very good, so your CG came out just right. Keep experimenting to cross that 60 second mark . You are so close. You have a good big flying field.  

I just noticed. Very good Hitesh: You are right handed as seen in your second video post reply # 155. your glider in glide test went to the right. Yet in your latest wonderful video Rely # 317 you launch the glider holding in your left hand and rubber on your right. Result is that it climbs to the left and glides to the right. Perfect and good flight. Kudos to you to figure this out. Very nice !
Bravo

All Lunchbox builders,

Please watch the Lunchbox Contest thread too.

It shows the leader board, and the additional prizes offered by Glidiator and Free Flight!

http://www.rcindia.org/free-donations-and-sweepstakes/next-contest-20second-flight/msg311037/#msg311037

Sir very excited about the prospect of laying hands on FAI rubber.

So, I finally did some new testing in a much smaller space with a different photographer(primary photographer not available)
1.Initially the elevator tab was too big (some people said so) and it was almost doing a loop in the transition phase.
2.So today I cut the span of each elevator tab by half
3.Then I realised that as a result of this now its very nose heavy. So I Kept removing nose weight
4.After a point it started looping so i added some weight.
5. Now it shows some very weird behaviour which I am not able to understand at all. It climbs well, then dives very fast. after this it recovers,pitches up too much and somewhat glides. When I do it from an altitude of 22.5m(5 storeys) it gets sufficient time to pick up speed so glides fairly well after that. I will be going back to my cousin's place so that I have a much larger flying field for some serious testing.

This is much worse than it what it was earlier.

I collected some data. With this poor performance and trimming, it travels 51.5m for 22.5 m of altitude drop.
I have made a collection of the better videos of today's lot. Uploaded on my youtube channel.

I had earlier posted all the above in a not so clear fashion along with a mish mash of videos brashly uploaded from field to our whatsapp group for this contest. Based on that, Iyer sir gave me some recommendations , which I have some trouble comprehending.

I am sharing those recommendations here, hope Iyer sir won't mind.

Failure to recover from a dive is SURE indication of lack of decalage (ie, having no up elevator at all or perhaps even having slight down elevator).
Suggestions:
1. Remove all trim tabs/wedges
2. If possible, check that there is no down elevator built in.
3. Balance at the suggested CG location. If more than 2-3mm away, it has static imbalance, which is possibly being compensated by some dynamic (airflow) imbalance at some speeds, but not at other speeds.
3. Please change your launch technique for test glide.
4. I've explained many times the correct way to do the test glide to establish the trim for proper glide. See for example SI74's reply #286 on Lunchbox thread.
5. PUSH the model towards a point ON THE GROUND about 30' away. POINT THE NOSE IN THE DIRECTION OF FLIGHT. It has to be in the gliding attitude, ie slightly nose down, and at gliding speed. (That means slow enough to avoid climbing above launch height, and fast enough to avoid landing in say 20' or less.
You are launching it nose high with downward force. So it starts with very high angle of attack, not representative of the glide phase.
6. All this will take only a few minutes.
7. Then try a horizontal catapult launch with say 2 rubber bands pulled to twice their length.
8. You'll soon be UP, UP and AWAY!
Best wishes.

It would be very nice if Iyer sir further extends the deadline, so that I can do some real testing when cousin comes back to station on Thursday, Dec 17 2020.
Its a very humble request sir. I was a bit busy with college endsems till yesterday and multiple other competitions.

Karthick: Sharing a few observations from my point of view:

1) Per your videos, Your glider has no transition. Goes up and comes down.  If it fails to do a transition, then glider goes up and down may not be related to incidence at all. You must bank the right wing and see if the left transition occurs. The way I see your video, you have almost no or hardly any  bank angle when catapulting your glider. Need to bank the right wing , say, start at 30 degrees .Then experiment for your glider if you need more bank or les, all for the same launch angle. Change one thing at a time ONLY. See Hitesh's video for launch and bank angle.

2) Lunchbox is a world famous glider design specially for new comers. The designers knows the wing and stab areas. For this glider Mr. John has correctly calculated TVo, tail volume coefficient. It is all related to the ratio of the stab and wing area and the moment arm versus  MAC. In short, take his word for it, never cut down the wing or stab areas. When you put the tabs on the stab , it looped. Very good ! Expected. Now the tab is either  too long or thick. So  you can make  it short , 1 mm at a time, or sand it down with a nail file to thin it. Keep catapulting and sanding until the loop is just out, not too much.

3) CG affects only the glide phase. Your glider may need a bit ahead or slight behind.  Till you get the launch and transition correct, just keep the CG as shown on the plan.

I suggest put the correct stab on back again, and the tabs are 1/32 inch thick only about 6 mm long. My glider just needed that much only. Try it .

In Reply # 318 please see the comments in Blue just modified after observing all of Hitesh's video.

Please make a note of it, may help you in future if your glider just want to glide right. Very helpful, what he did.

You may have the left stab tilt and yet your glider wants to glide right. In that case, do as Hitesh did. Reverse your launch hands, glider in the left hand and rubber in the right hand.

A slight skewed  LE of the wing the right (very tiny bit off the fuse center line) will negate all stab tilts. Also if your washin tab is too thick or long, you may experience similar  right glides. In this case, best thing to do is reverse your launch hand as Hitesh did.

PS: In such a case, left climb and right glide, you may have to put the washin on the right wing  should your glider spin in during the glide phase to the right. Remove the left washin in this case too.

Quote from: Karthick Ashwath on December 12, 2020, 11:00:12 PM
Sir very excited about the prospect of laying hands on FAI rubber.

Good to hear that. I know you can do it.