BUSHCADDY 3670 - AUS.

Bushcaddy flying again

2009-11-26T01:55:00.000-08:00

Bushcaddy flying again

Well it has taken a long time but finally the Bushcaddy is flying again in a tailwheel configuration. As it was meant to be.

The trigger for the conversion was serious cooling problems with the Jabiru 3300 six cylinder engine

I realized I had to radically modify the coaming and ram air ducts and I thought if I am going to go to all that trouble I needed to fix the nose wheel issues as well. At the time it seemed the best solution was to get rid of the nose wheel and make it a taildragger as it was designed.

Like most projects amateur man undertakes, they always take three times longer and cost twice as much as origionally planned.

Well here is the "Bushcaddy" in its tailwheel configuration. It does have doors, but I have been doing the test flying without them for the present.

For those interested, I modified the door hinge set up so I can very easily remove the doors.

The aircraft flys well without the doors, and there is very minimal wind bufferting of the cabin.

A stern quarter view.

Above.

This is the original aircraft as a nose wheel aircraft. It was very easy to land in this configuration, but the nose wheel set up was not very successful and the previous owner had already broken two nose wheels on grass airstrips in less than 50 hours of flying. This plane is a "Bush" plane and is meant to land on rough bush airstrips. If I was going to keep it as a nose wheel aircraft I would need to install a long travel front wheel suspension like a Savannah or a Zeneth.

I installed a large skylight in the roof for better visibility. With all the gliders flying around Boonah I wanted better visibility, and coming from flying a Drifter for 12 years with its excellent visibility, I didn't like not being able to look up and see what was above me.

The large skylight for better visibility. I strengthened up the opening with Aluminun boxing and extra angle gussets. (you can see one of the four gussets in the RH corner) The angle "thingy" in the middle is the wing tank fuel sight gauge.

I marked out where I was going to cut. I was agressive with the size of the opening as I really wanted visibility.

The cut out.

Note the origional flate plate corner gussets. I wasn't happy with these now I had a big hole in the roof so I bolted in some angle gussets on top of the originals. There are four in total. One in each corner.

Here you can see the angle gusset.

I moved the engine forward 183 mm and down 50 mm when transforming it to a tailwheel. I was given the forward number by the factory, but after doing the weight and balance I could have gone a little further forward to put the empty weight and balance right on the forward limit. As it is now, it is back 40 mm from the forward limit and now I will need to limit the weight I store in the luggage compartment behind the seat for CofG reasons and not MTOW reasons.

This was the first Bushcaddy flying in the world with a Jabiru engine, so there are some bugs to be worked out. A second Jab powered Bushcaddy recently had its first flight in the US, and it appears the owner is having some of the same problems I have been having.

Above. - This is the original dash and Y shaped control stick. The "Y" stick is great for training or dual flying purposes, but my aircraft will mostly only be flown from the left seat and I wanted a single stick. I still have the original one and it would only be a simple matter to switch them over if there was a need in the future.

Below. - This is the new dash and joy stick.

I have gone for a single pistol stick grip with 4 buttons on the grip. I have 2 PTT buttons to activate the UHF and VHF airband radios. The other 2 buttons are to change the memory channel and flip the frequencies of the Icom unit. All this can now be done from the pistol grip, rather than having to swap hands on the stick and lean forward to reach the radio.

The reason for the extra gauges. - Well what can I say? It is a sort of affliction I suffer from.

I installed an electrical grommet to act as a friction nut. I replaced the rubber insert with nylon beverage tube, and it works really well as a throttle friction.

The original configuration caused serious overheating issues. I have now made oversize ram air cooling ducts and installed a second "back to back" oil cooler. These oil coolers now have their own separate egress tunnel. Note the two oil coolers at the bottom of the photo. (edge on)

See above the old original ram air duct is on the right, and the new, much larger, duct is on the left.

The initial test flights are showing absolutely no cooling issues.

This is the first Bushcaddy in the world to be fitted with a 6 cylinder 120 HP air cooled Jabiru engine. The problem is that the supplied cooling ducts are meant for slippery aircraft flying at 100 to 130 knots. The Bushcaddy is a tough, boxy, bush aircraft that cruises at around 80 knots and the original air ducts and oil cooler are just not adequate for this aircraft.

Perhaps cooling will be no issue in cold places like Canada, but we have summer air temperatures that get to over 41 deg C in the shade (106 deg F.) in Queensland.

I also installed a three blade 62 inch, ground adjustable Petroni composite propeller. The original wooden propeller was absolutely hopeless, and the aircraft just wouldn't perform.

So far I am very happy with this Bundaberg made propeller. It is very well constructed and exceptionally smooth.I originally set the pitch at 13.5 deg. But the engine would not rev out properly and ran rich on takeoff. I have now changed the pitch back to 12.8 deg and It is performing much better. I will do some more testing at this pitch, but I feel I may need to go down to 12.5 deg pitch to be able to access the full power of the Jabiru 120 HP engine.

Note: You need to be very careful with coupling composite propellers to direct drive engines like the Jabiru, because of the "pulsing" issues that destroy props. To the best of my knowledge the Petroni Propeller is the only composite propeller designed and constructed strong enough to withstand this pulsing, as happens on direct drive Jabiru engines.

I had to make a new fibreglass nose cowl. Note the inlet for the oil cooler under the spinner, and the oil coolers own egress duct coming out between the two exhaust pipes. I have a flap at the back of the tunnel so in winter I can partially or fully close off the air passage from the cockpit.

The original seats were nearly 75 mm thick and very comfortable, but I am 6 feet tall and this put my head level with the wing root and I had to bend down to see out the side windows.

I Took out the 2 or more inches of foam from the seats and and then cut out the solid wooden base and installed a webbing base. This dropped the seats down around 2 inches and they are still very comfortable.

I installed an electric elevator trim, see above on left elevator.

I control this from a switch right beside the throttle. (see above) The trim indicator gauge is on the right of the photo. The trim in this configuration is very effective and so easy to adjust. Far better than the old system of having to constantly reach down between your legs to work the mechanical trim wheel.

I used the parts from the old elevator trim to make an aileron trim (I copied mine off John B,s Bushcaddy from SA). In the past if I was one up or only had full fuel in the port tank I needed to hold my knee against the stick in cruise, otherwise the aircraft wanted to tilt to the left. Now I can adjust for neutral trim.

Purchase of Bushcaddy 3670

2009-07-15T01:34:00.001-07:00

I purchased Bushcaddy 3670 in mid 2008. Its home base was Cabolture Airport in Queensland, Australia.

I was very impressed with this little plane as it appeared to be very well built by the previous owner and looked real presentable. In fact the workmanship was excellent, and a real credit to its previous owner/builder. However this aircraft had not flown for two years and I could see some initial issues, so I was prepared for some teething problems, and the price was right.

I purchased Bushcaddy 3670 in mid 2008. Its home base was Cabolture Airport in Queensland, Australia. I was very impressed with the little plane as it appeared to be very well built by the previous owner and looked real presentable. In fact the workmanship was excellent, and a real credit to its previous owner. However this aircraft had not flown for two years and I could see some initial siiues, so I was prepared for some teething problems, and the price was right. This aircraft was built as a nose wheel plane, as I was informed the owner-builder had no training or experience on taildraggers. <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_Na_LV8MbvUw/Sl2a1c5VVII/AAAAAAAABps/NKwrxoL-tfM/s1600-h/BILD0357.JPG"></a>Bushcaddy at Cabolture, just after purchase. <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://1.bp.blogspot.com/_Na_LV8MbvUw/Sl2a1rQThjI/AAAAAAAABp0/Zkmj1r1S8Ms/s1600-h/BILD0422.JPG"></a>This particular aircraft was the first in the world to be fitted with the Jabiru engine, and to the best of my knowledge, the only aircraft actually flying with the Jabiru engine at the time of writing. There were issues here. more later. <a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="http://2.bp.blogspot.com/_Na_LV8MbvUw/Sl2a186_8XI/AAAAAAAABp8/GkYX7UfFwLg/s1600-h/plane+020%282%29.jpg"></a>The trike undercarriage. This aircraft had broken two sets of nosewheels. This was the third variant. The first was the original factory nose wheel which was just not up to the harsh Australian grass airstrips. The second locally sourced "lightwing" model also failed, and the third version was fitted with double bracing. See photo above. The nose wheel was direct coupled to the pedals to give front wheel steering. <span style="font-weight: bold;">Problem: </span> The brake cylinders were fastened to the floor pan, and not the pedals themselves. In normal tail wheel configuration, this would not be a problem, however because there was a direct linkage to the nose wheel, the opposite brake would come on every time the front wheel was turned. This was ok when going forward, as you would get nose wheel steering and differential braking in the one movement, however it made it impossible to push the aircraft backwards. The only was to go backwards was to go to the tail and pull it down, lifting the nose wheel off the ground and pull it backwards. The fix was relatively simple and was done later at the new home airfield at Boonah. This involved unbolting the brake cylinders from the floor pan and welding support brackets to the brake pedals.

This aircraft was built as a nose wheel plane, as I was informed the owner-builder had no training or experience on tail draggers.

Bushcaddy at Cabolture, just after purchase. (Click on the photos to get a larger view)

The original dash panel.

This particular aircraft was the first in the world to be fitted with the Jabiru engine, and to the best of my knowledge, the only aircraft actually flying with the Jabiru engine at the time of writing. There were issues here. more later.

The trike undercarriage. Version three.

This aircraft had broken two sets of nose wheels in only 40 hours of flying. This was the third variant. The first was the original factory nose wheel which was just not up to the harsh Australian grass airstrips. The second locally sourced "lightwing" model also failed, and the third version, another "Lightwing" system was fitted with double bracing. See photo above.

The nose wheel was direct coupled to the pedals to give front wheel steering.

Problem: The brake cylinders were fastened to the floor pan, and not the pedals themselves. In normal tail wheel configuration, this would not be a problem, however because there was a direct linkage to the nose wheel, the opposite brake would come on every time the front wheel was turned.

This was ok when going forward, as you would get nose wheel steering and differential braking in the one movement, however it made it impossible to push the aircraft backwards. The only way to go backwards was to go to the tail and pull it down, lifting the nose wheel off the ground and pull the aircraft backwards.

The fix was relatively simple and was done later at the new home airfield at Boonah. This involved unbolting the brake cylinders from the floor pan and welding support brackets to the brake pedals themselves.

The original nose wheel. This was just not up to Australian bush strips, or for that matter, any bush airstrip, (in my opinion), and soon broke, causing a prop strike.

Nose Wheel, version three installed by the previous owner-builder. This is a modified "Lightwing" nose wheel assembly. I soon found out that this was also not satisfactory.

The problem I found here was constant flexing of the support brackets and even the firewall itself on the first test flights, and Cabolture has a good grass airstrip. On checking the set up for "flex" I found there was NONE in the system itself. All the flex was in the support brackets and the firewall. If I kept going with this set up there would soon be a third nose wheel failure. But this time I would be the pilot and I would be footing the repair bill.

The system used a 1 inch diameter cylinder of polyurethane. This had no flex at all. In fact I put the slug in a vice and I could not compress the slug one bit, not even 1 mm. No wonder "Lightwing " nose wheel aircraft had a reputation for braking nose wheels. You might as well have installed a solid steel bar for flex. The guy who designed this set up could not have checked his work.

The original "non compressible" polyurethane slug.

The fix was easy. I cut out a number of separate sponge rubber 15 mm deep slugs, and inserted these instead of the solid single polyurethane slug. I now had about 30 to 40 mm of flex instead of the zero flex that I had previously. Nothing like the front wheel travel of a Savannah or 701, but sure better than before.

I replaced the hard red polyurethane slug with the soft spongy rubber discs shown above. If I could have found the right sized spring I would have tried that as well. The red polyurethane had absolutely no "give" . The soft rubber did have some spring.