The following is a step by step guide to fitting the stretch kit.

The stretch kit itself has not been wildly popular as an upgrade option, rumour has it that the extra length blades place a larger loading on the motor with little in performance gains. I will be looking into this as part of the flight testing as well as doing a side by side comparison of motor loading on the normal 'woodies' versus the 335mm stretch 'woodies'.

Given the above statement it is worth pointing out that the stretch kit boom is a requirement if you wish to run the Align Carbon Fibre blades, without the extra lenght in the boom a tail rotor strike between the main and tail blades is inevitable.

So what do you get for your cash? The pictures below give a quick overview of the items in the stretch kit. These are basically
  • 335mm wood blades
  • Longer gold coloured boom
  • Gold undercart skids
  • Longer narrow profile tail belt
The following pictures and text guide through the quick way to swap tail booms with minimal build/rebuild work.

The first job is to undo the screws on the horizontal stabiliser and remove it. The tail pushrod should be disconnected from the tail control horn under the tail gearbox. Lastly the four screws in the rear of the sideframes holding the tail boom in place should be loosened. The tail boom can then be pushed into the side frames creating some nice slack in the belt around the tail drive gear. Pictures of these steps follow:
Unhook the belt and then loosen the screws on the tail servo mounts. Undo the screws through the horizontal stabilizer and remove. Pop the rear tail control horn ball link off so the tail control rod is free to move backwards.You should now be able to slide the boom backwards out of the main frames, take care not to pull the tail servo wire and slide it along the boom gently as you remove the boom from the frames.
You should now have the entire boom and tail assembly removed. Which should look something like the picture below left. Undo the two screws on the vertical stabilizer and remove, see below right.
In order to remove the old short boom and belt all four of the tail gearbox screws must be undone and the two halves separated. See pictures below.
The new belt can now be installed and the gearbox halves screwed back together. I then thread a piece of string through the new boom and attach one end to the belt, then pull the belt through the boom using the string, it's almost impossible to just push the belt through the boom or expect it to just dangle through. Pictures below.
Once the belt is threaded it should be orientated such that there is only a 90 degree twist in it for mounting onto its drive gear. I normally use a piece of sellotape to hold it in this orientation so that I don't have to worry about it moving when I'm trying to fit the boom. The boom is then inserted into the tail gearbox and the vertical stabiliser fitted to hold it in place. The boom should then be inserted through the tail servo mount brackets and into the mainframe. The belt should be placed onto the tail drive gear and the correct tension applied. The tension I appy is just enough that pinching the belt just behind the drive gear will not quite let the two belts touch. Tighten up the main frame boom screws to hold the boom in place. Now fit the horizontal stabilizer and slide the tail servo down the boom so that the tail control rod can be popped back onto it's ball link. Make sure the servo is positioned correctly on the boom for correct throws on the tail and then tighted up the servo holding brackets onto the boom. Some more pictures illustrating this below.
That's the hard bit, the stretch kit also comes with nice new gold skids, which simply replace the old silver legs, although getting the legs out of your undercart struts will be a problem if you followed the instructions and CA'd them in place.

The 335mm blades in the stretch kit will need balancing before fitting. The kit does not come with extra brass bushings for fitting into the hole in the blades, so the bushing will need to be removed from your old shorter blades.

That is everything in the build, the next question is how does it fly and what extra loading do the larger blades place on the motor/lipos. The details of the blade load testing can be found on my blades page where I have compared the relative amp draw across various different blades including the 335mm stretch blades.

Update 04/05/2005

I should have updated this by now as I have flown the stretch blades quite extensively. Certainly the larger blades require a more powerful motor to spin them and they also increase the current draw quite significantly over stock blades. These are the downsides to running the longer blades. On the positive side they provide quite a bit more lift and vertical performance than the stock blades. Additionally the T-Rex feels more stable running the longer blades. However when pushed into aerobatic and 3D flight the longer blades slow things down and the roll rate is reduced. Additionally the Align carbon and also the SAB carbon blades provide similar levels of lift but without being quite as long. This must mean some level of flex is occuring in these longer blades which in turn reduces their overall power relative to a shorter and more stiff carbon blade. With regard to value for money I can't fault these blades as they provide a good deal of stability at a small price in terms of 3D capability.