Thursday, 22 March 2012

Viking engined Twister in Oz

The Australian Twister agent is putting a Viking engine in his one.

It will be interesting to see how it goes for him.

I wonder where the radiator will go?

Should be an interesting cowling exercise to follow.

These pics are of a US based Twister that is also having a Viking engine (I think).

Week 31 - Port wing update and wing stands

Hours to date: 305.25

Passed the 300 hour mark - so if my estimate of 1,500 hours holds true then we are 20% of the way through this project. Hopefully I can keep up my 12 hour per week average.

I've brought the Port wing up to the same standard as the Starboard wing now. 

There is nothing really left to do without the fuselage so I am now building a wing stand so the wings will have somewhere safe to sit when I take them up to Pete's.

I also found some pics of a newly registered Twister in the UK. Another fixed gear one - although with the old style tailwheel. Paint job looks good.

Wednesday, 14 March 2012

Week 30 - Fill, sand, fill, sand etc.

Hours to date 295.25

Started on the filling now. Pretty easy going. But man does that filler stink! Lots of good ventilation and a mask is essential. Quite enjoy this job except for the smell.

Pete says to use Micro as a filler on weight critical parts - such as control surfaces.

So the Rudder as you will see below has Micro on it, the wings and tailplane have normal filler.

I also decided not to be so lazy and completely reinforce the inside of the rear rib behind the flaps. Really poor access for this job - so a bit of a mission but got there in the end. Not a pretty piece of work so no photos!

Switched wings now too so I am bringing the Port wing up to scratch with reinforcing of the root rib with Carbon. After that there will not be a lot left I can do - so soon it will be time to swap out with the fuselage.

Tuesday, 13 March 2012

Fiberglass 101 DVD - Highly Recommended

This DVD is just brilliant and if you are considering building a Twister then you should definitely buy it and watch it a few times.

It won't win any Oscars for acting, directing or cinematography but to hear a guru such as Sam James share his decades of experience and knowledge like this is just invaluable. It is almost totally practical too - only a bit of history and theory at the start then it is straight down to how to build parts. Then in the second half Sam covers building moulds. 2 hours of gold.

All-in-all a must have for any budding builders out there.

Buy from Tech books on the below link.

Wednesday, 7 March 2012

Silence Twister Hybrid

I've been thinking...

With the ever rising cost of AVGAS and the ever increasing power of batteries there will come a time when the humble piston engine will have had it's day.

We are some years away from that moment but in the meantime the most logical solution is a hybrid.

Because batteries take so long to charge up again this is the only practical solution for the foreseeable future - until there is a step change in battery technology.

Click on the pic below for a bigger view which outlines my 'mark 1' configuration.

Advantages of this set up are: 

Reduced running costs (Jet A-1 can be bought for less than half the price of AVGAS here in the UK - plus the battery charging cost is a tiny fraction per KW of power output). Also the Twister would only need approx 45kw continuous as a sustainer in the cruise - so fuel burn of the turbine could well drop to 20 LPH.

Potentially quiet operation in noise sensitive areas - battery use alone for climb out to cruise (5 mins) or approach to land. 

Greater fuel availability (Jet A-1 is much more widely available than AVGAS). 

No loss of performance with altitude (actually the turbine runs better the higher it goes).

Potentially more reliable. (In the early days this will not be the case but turbines and electric motors have extremely good track records of reliability so should be able to be made this way in this set-up).

Reduced drag. (With a very narrow cowling and only a small NACA inlet on the bottom plus the thrust from the turbine this has potential to be a more efficient setup than an air cooled piston engine).

Increased performance. (The electric motor produces phenomenal torque and 135hp for a 60 second peak, combine this with the thrust from the turbine and the climb rate would be MUCH better than standard - also the cruise speed would most likely be higher, or the same speed but with a much reduced fuel burn)

Disadvantages are: 

Initial cost of turbine and battery (both unknowns at the moment and the Bladon turbine is not in serial production yet). 

Potential noise issues with the turbine (if it cannot be made quiet). 

Weight (I believe the battery will push this over the traditional air cooled piston set up for weight).

Approval. (I can see the LAA and CAA taking a conservative approach here and not liking this one bit! So the UK may not be the place to take on such a challenge - the USA or NZ with their Experimental categories would be much better for catering with such innovative thinking)

Whilst the technology and affordability are not quite there yet it certainly points the way forward.

Maybe one day we will all have a wind turbine and solar panels on our hangers charging up our plane and be able to fly for little to no fuel cost.

As Howard Hughes would say (most likely repeatedly) "It's the way of the future".

Link to a video about the Bladon Jet here:

Saturday, 3 March 2012

Week 28 - Full and free movement

Hours to date: 275

Well the starboard aileron is now pretty much complete. Just got to add the counterweight and it's done. The factory were very kind to send me a replacement bell crank bearing free of charge - thanks Matthias!

Quite a time consuming task fitting the control surface and getting it to have the right deflections without snagging on anything. Got there in the end.

The counterweight hole had to be made quite a bit bigger but the pushrod hole and aileron root end just needed fine tuning.

After that it was back to the root rib to reinforce with carbon strips. Worked out easy this time now that the edges of the rib were smooth with a little ridge of micro on the top.

It will be time to switch back to the Port wing very soon and get that up to speed.

Fully deflected down - 90mm (wing is upside down)

Fully deflected up - 100mm

Inside wing view of the bell crank and pushrod.

Micro ridges added to the edge where the carbon reinforcing is to go.

Carbon in place - went on quite easy with the ridges.