There are a couple of things you can do in addition to great suggestions in reply to all your posts. I fly pattern a lot and have Zen50, 90 etc. I flew a lot in New Delhi when I lived there and am used to flying zero nitro conditions there and aware of high cost of nitro etc. I was just lucky, I used to travel to HK, JA and Singapore every month.

1. A properly setup Zen50 is a great aerobatic pattern machine, knife edge, axial rolls, unlimited vertical etc. the larger Zens 90 and 120 are better of course. however...
2. The Zen series of models prefer a rearward cg; use suggestions in this and other forums; pull the fuel tank rearward, even a little bit helps, move battery back using only a heavy duty extension. I also use 1oz (4x.25oz) at the trailing edge of the fuselage, installed vertically just below the tail fin.
3. Use 1/8!QUOT! or 5/32!QUOT! shims under the leading edges of the retracts to keep the struts facing forward to stop a nose over during a landing.
4. Use Lite wheels replacing originals.
5. Lighten the spinner backplate (if you are using a metal spinner) by drilling a few holes in the backplate.
6. Use a lower pitch prop to let the engine run at rated rpm on zero nitro conditions.
7. Replace retracts with better quality ones, Not easy for you to get them in Pakistan though unless you have someone who is traveling abroad regularly.

Lastly, a piece of advice to the modeling community in Pakistan: when selecting an engine for aircraft running on near zero nitro content, select high compression engines using hot plugs(I hope I got that right) that do better in zero nitro content. In the OS range, look for an older OS50fsr, an extremely powerful engine that will run great on zero nitro. Another range of superb and extremely powerful engines is the ASP brand, made in China. Ballistic power on zero nitro. However these engines benefit from better performance using an OS carb. The ASP61 for medium size and ASP108 for larger aircraft to 11-12lbs are great. All this is from personal experience. You may also want to consult some UK forums where they use a much lower nitro content due to high cost of nitro fuel; I should know, I lived there for too long.

If you still have problems, email me and I will try and help you with more advice and tips to improve your flying experience. By the way, I stopped by in Lahore for several days at friends, when I drove from London (UK) to New Delhi (India), yep done that several years ago.

PineBaron