New engine bushings - off the shelf !

It was time to replace my engine mount bushings. This has always been a pain as they are normally cut out of "a sheet of rubber" without indication of specific characteristics... Last time someone in the Avid Flyer club organized a grouped order at a rubber supplier. This time I was looking for a different solution.
After hours on the web I found a model that appeared to have the correct form factor and size. 

Talking to the manufacturer (Hutchinson Paulstra click to visit) they recommended the softest version. Due to the central part of the bushing being enclosed in the engine mount they don't give the shores rating as this could be misleading. 
The reference of the ordered model is 530903-21.


While the final shape of the bushing looks like the original it is more sophisticated and give a very serious impression. 
The central metal tube is wider than the original but the original tube fit perfectly inside the wider tube. No need to adjust the length. The fit between engine mount and bushing is perfect and the replacement of the bushings can be done in 30 in minutes.

After several hours in the air with the new bushings I'm very happy with the result. Vibrations are reduced and I have noticed no adverse effects. I can feel it and you will see it in my next film...

The Wow-Prop...

When changing to the Simonini engine I increased the pitch of my 66 inch Warp Drive prop but had the impression I didn't get the performance I expected. After long back and forth with a Spanish propeller maker I ordered a 2 blade custom built 72 inch wood prop. It looked soo good... and under winter conditions it worked well - not so in the less dense air of hot summer.
I have just received a swept blade (Scimitar) 72 inch prop from NR-prop in Ukraine (also known as "Kool prop" or "Luga prop" but I call it to "wow-prop"...) 

 My first impressions are very positive:

• Very smooth
• Low noise
• 20+ km/h maximum speed
• 700-1000 lower RPM at normal cruise speed
• Unbeatable price
• Good experience buying directly from Ukraine

Click to visit the NR-Prop
(My only relation to NR prop is as a happy customer)

You can’t see the prop when it is spinning...

I must admit.. my 2 blade wood prop was, while being beautiful, not a success. So much for nostalgia…

I got really good take off performance but I lost in speed and got vibrations I didn’t need… 

Another problem I had not anticipated is the need for different pitch during really hot summer periods compared to the rest of the year…

So I increased the pitch on my old smooth running Warp Drive and put it back on. I gained 15 kph / 10mph (10-15%). We will see about the consumption...

Finally, a pneumatic tail wheel!

Original (solid) Maule tailwheel

Like most Avid Flyers mine came with the classic Maule tail wheel. I find the Maule mechanism working great but the solid wheel way too hard. On a smooth paved runway it works great but anywhere else you really want something more shock absorbing...
Real tundra tail wheels are ridiculously expensive as they require a complete tail wheel assembly so I decided to go for a low-cost compromise.
Matco sell a 6 inch pneumatic nose wheel that is also used in one of their tail wheel assemblies. (Links to wheel and tire)

It is made for a thicker axis but with a few tubes, ordered from an on line bearing supplier, it is easy to adapt.
I mounted it on the plane just before my last flight and made 3 landings. With approximately the same diameter the mechanism is working like before but the vibrations and the "shaking" is reduced. It is not a dramatic difference but well worth the investment.
It should be noted that the Matco wheel is, once in place, 750g (1.63 lbs) lighter than the Maule wheel.

BIG IS BEAUTIFUL

I just changed to 850-6 Aero Classic "Tundra" low pressure tires from Desser that got rave reports from Avid Flyer users who tried them.
Calling a 850 tire for "tundra" will make the true bush pilots smile, but I can live with that....

New prop

A new 2 blade wood prop, made to order by Aerobat in Spain, should arrive in 3 weeks...

DIY Lift Reserve Indicator

I have completely forgot to tell you about my Lift Reserve Indicator project. 

For reasons that we don’t need to repeat I have gained a particular interest in the stall point at landing... 

A traditional angle of attack meter is complex and expensive (and feels like overkill for an ultralight aircraft) but I found a number of articles on the web talking about  “Lift Reserve Indicator” (here is one, here is another, and you will find many others as well as "for and against discussions" doing a simple search…). 

While producing very much the same information as a traditional AOA indicator it is just a differential pressure gauge connected to a probe with forward and aft ports - and therefore at a fraction of the price and easy to do yourself... 

I got a 0-2.0" WC Dwyer pressure gauge from Amazon (but there is obvious other sources) and made a new gauge face using a inkjet printer... Inspired by the Icon Aircraft Lift Reserve Indicator I added a wing profile to the needle. It will make it more readable by the corner of the eye... 

The probe is an aluminum bar, (1 cm by 2 cm) as long I could drill (some 13 centimeters). It is mounted approximately at ~20% of the wing chord counted from the leading edge and leaning forward. The angle need to be refined in test flights to confirm the correct reading.  

If it works? I don’t know... but be sure I will tell you about it here once I have tested it in flight…

My "best" modification...

A modification that I made already some years ago, and have been very happy with, was making it possible to open the upper part of the pilot door as a window (like on a Piper Cub or Citroen 2CV…). 

I have now simplified my earlier modification and applied it to both doors. While you can open the doors in flight, opening just a window reduce the risk of stuff falling/flying out and creates less drag. Great for hot summer days, both before takeoff and for flying cool with your elbow out the window...

The window frame is made of 12 mm aluminium tube ("seamlessly" joined by inserting a 10 mm tube...). The aluminium tube bend easily with a cheap 12 mm copper tube bender.  

The window will stay open by itself as long as you fly “clean” but it will close just when you are about to take that perfect photo while flying the plane with your knees. So I installed gas springs to keep them open. The perfect re-use of the door springs when they can no longer hold the entire door.

To keep the windows closed I use Citroen 2CV window latches – this is not the only similarity between this plane and those amazing french cars… 

DIY Wheel caps...

Not really the priority at the moment but fast and fun to do... As the wheel nut is extruding I could not do flat wheel caps and I was scratching my head how to do the required shape... The easy solution was heat-forming a sheet of polycarbonate... 

All it takes is a scrap piece of polycarbonte (from when doing the windscreen or windows), a heat gun, a right sized hole and a slightly bigger round object. Peel off the protective film from the "wheel side" and heat only that side. The rest you can guess...
I painted only the wheel side and this gave a nice glossy finish.

I'll be back soon with a more complete update...

Poor man's Sonex trim...

I have always liked Sonex trim system but you just can't buy everything you like just because it would be nice on the plane (my wife says)... 

...but I'm allowed to build anything I like as long as I'm using scrap material...

If God had intended us to fly, he would have given us more money...

I know you have all been there... trying to avoiding to say that what you are looking for is to be used in an airplane - just to save money, or rather, not to be ripped off...

This was the original seat in my Avid Flyer. There is nothing fancy about it, light weight, simple and "so and so" comfortable. But apparently it was very tasty to some rodent that really liked the stuffing... 
So I took it to an old style shoemaker near the airfield who I knew made seats for old cars and bikes. Really nice a cool guy so when he asked I told him it was for an ultra light aircraft (and not a private Lear Jet). We looked at different materials and he told me that leather (that was what I wanted) would be expensive and suggested some synthetic alternatives. So how much would it cost... Well he said, while he got euro symbols in the eyes, about 1.000-1.200 euros depending on the material... No point in asking for the price in leather...
And believe me, he was seriously thinking I would pay that kind of money. Where do they come from? Who made them think people who fly have money left?
It was too cold to work on the plane anyway so I bought a big piece of leather for 50 euros, took my old hand cranked Singer sewing machine and, with the seats from my long gone MGB in mind, I did the work myself. It took me a few hours and while the result is not "pro" it is good enough for me - particularly for thousand euro less - and it will look better when "worn in"!

Details

Winter flying is fun but cold... 
Last winter, flying with my skis, I was really missing heating in my plane. Surfing the web I found what appeared to be an interesting solution. It arrived today from T7DESIGN:

It is an incredibly compact heater (maybe that is why they named it "Micro Heater") that weigh only 580 grams while rated for 2,2 kW. Well worth a try - it can't get any colder anyway...  

Differential breaks 
I never succeeded to hold my plane on the foot breaks and had difficulties applying even pressure on the breaks when trying to slow down rapidly so I replaced the individual foot breaks with a central break handle on the stick already some years ago. It worked very well and I never had any problems with the ground handing due to central break.
But it is not perfect, you cannot turn "around one wheel" when needed and turns can sometimes be wider than allowed for, particularly on mountain fields. So I decided to improve my system by installing a dual break handle on the stick. It is a kit of 2 bicycle handles that I merged into one. I'm sure it will be easier to apply even pressure by hand than by foot.

Rain and firewall fuel taps

As you have seen in the comments there is a discussion about excess oil in heads down cylinders and fuel taps. The theory is that with wing tanks (high wings) fuel continues to slowly flow through the carburetors due to the gravity feed and that the oil is deposited in the cylinder head while the fuel evaporate or disappears elsewhere – if there is no fuel tap prevent this.

As I’m normally not a friend of fuel taps (risk of forgetting them, point of obstruction, leaks…) I had reduced them to a minimum.

I have reconsidered and have now installed a fuel tap on the firewall, operated directly on the dashboard. I did this some time ago but as the weather has been dreadful most of the time and particularly so when I had the time to fly I have not yet been able to test this.

As soon as I can confirm that this is actually solving the problem you will be the first to know!

Simple and efficient

One reaction I got on my video was a suggestion on a very simple and efficient system to retain/secure the spark plug caps.
4 washers grinded down to oval shape, 2 holes in each washer and a piece of 4mm bungee cord…Adopted and implemented, thank you MichaeL!