Check to make sure your receiver crystal is plugged in tightly. It might've come loose when you planted it.

How the plane behaves when the transmitter is off doesn't mean anything. It is a bad habit, to plug in the battery before turning on the transmitter. That means any stray frequencies in the 27 MHz band could control your plane. Bad news.

Go over all the internal connections, especially the battery connection. The Tamiya plugs that come stock with the plane really suck. They seem OK, but they don't make a good constant connection. Buy some Deans and replace them. (or HAVE them replaced, if you don't know how to solder)

If none of this works, you might've busted up the receiver crystal when you planted it. That would be the perfect opportunity to replace that receiver and T-Hawk radio system with a proper, hobby grade one. It will exceed the cost of the plane if you buy new. The original servos, you will still be able to use; same with the electronic speed control. If you look on ebay, you can score a Futaba Conquest 4 channel radio for about $8. Find a decent FM receiver from Futaba, and you're all set to go again.

I know this is probably not what a buyer of an RTF plane wants to hear, but it is the truth.

I've pounded my poor T-Hawk into the ground a few times myself, and was lucky not to bust anything up too badly. I'm on my second wing, second set of tail feathers and third propeller, but I'm a pretty good flyer now.

I've got 5 other planes in the works. Some day, I will probably come back to the T-Hawk and put a proper receiver in it. I bet it will fly 100% better. It will certainly have more throttle resolution, hehehe.

Jeremy