Here we go!!

[skyfox1]

Great to see video Pud all looks great next a good long flight .

 

Cheers Geoff

 

 

[Powerin]

The long awaited video of the test flight has finally been edited - thanks GayGirl, and uploaded to Utoob.Check it out here

 

Pud,

 

and of course GayGirl:

 

 

Peter

 

 

[Piet Fil]

Pud,

 

Good vid, I am envoius of the joy you will have owning your own plane. One day I'll follow this path.

 

Enjoy and be proud (PS: Gret editing GayGirl)

 

Phil

 

 

[Tomo]

 

 

[pudestcon]

Are you looking after that brand new 582 Pud? Have you done a Cof G check on it also? Nev

The 582 is running like a dream Nev, maybe a touch hot at close to 80 degrees indicated on the water temp gauge (both EGTs at 1150 degrees) but it does not go any higher. Initially the fuel burn was around 18-20 litres per hour but on the weekend the burn was 15 litres for one hour, switch on to switch off doing circuits. The CofG check was carried out by Steve Vette and duly documented; I must confess I wasn't there when the CofG was done but the aircraft handles very well and will fly hands off straight and level at 5200 RPMs, no trim on the elevator but manually adjusted rudder trim with just a touch of port trim in. Maximum RPMs is 6400 swinging a 3 blade Brolga through a 2.58:1 reduction box. Sorry can't remember the pitch:rolleyes:

Pud

 

 

[pudestcon]

Thats great Pud. How proud does that make you feel mate.Cheers Scotty

It's all good Scotty.

Now has the frustration ended for you yet?

 

 

[pudestcon]

Goodonya Pud and next time you see Steve Vette,please say G`Day for me!Cheer,

 

Frank.

I'll do that Frank, Steve is a sometimes poster here under the name AVU.

 

Pud

 

 

[pudestcon]

Yeah Pud ....Great shots ... I like your "exercising the undercarriage" comment, Ya gotta do that ... its a test flight ...ya gotta bang it on to test the legs ... .

Well done buddy, it must be so good to go flying when you want for a gallon or two of 2 stroke.

 

David

Yep, it's all good David:big_grin:.

We went over the landing gear very closely after that landing and found some looseness in the main axle bolts and the tail wheel spring assembly. It's all good now and hasn't moved at all since, with something like 30 landings done. The tail wheel shimmy is causing me some concern though - not quite sure what I'm gonna do there yet, but I'll address it on Sunday. Was thinking maybe some friction washers on the main pivot bolt would dampen out the shopping cart woes. I can't see how to change the castor angle at this stage; besides, there are 2 other Thrusters in the same hanger with the same castor angle and no shimmy.

 

Pud

 

 

[skyfox1]

Hi Pud l had a similar problem with my Drifter fricton washer didnt seem to help ,the wheel was to close under the swivel point so l have moved the wheel back so it trails further back no shimmy at all now .

 

cheers Geoff

 

 

[pudestcon]

Hi Pud l had a similar problem with my Drifter fricton washer didnt seem to help ,the wheel was to close under the swivel point so l have moved the wheel back so it trails further back no shimmy at all now .cheers Geoff

That's interesting skyfox1, are you saying that the pivot point and axle were to close to being perpendicular to one another, and moving the axle further to the rear of the pivot point solved the issue?

Pud

 

 

[Guernsey]

Looks good Pud, big oscillation in the tail wheel there, maybe needs some more castor?

That tail wheel oscillation always occurs on the first flight, it has nothing to do with anything mechanical.............

Just like any dog the aircraft was so excited that it wagged the only movable part of it's tail.

 

Alan Marriette (the forum wag ).

 

 

[facthunter]

Tailwheel shimmy was bad on my citabria sometimes (on tar) to the extent that it would destroy the tyre in about 3 landings if you did nothing about it, My usual fix was to taxi tailwheel up, but that is a bit difficult and "cowboy". The cause was put down to the alignment of the pivot. The axis should be vertical. ( at right angles to the ground).

 

Two thing affect shimmy, the distance behind the pivot axis and the angle of that axis to the horizontal. I would not suggest increasing the damping as it will become harder to control at low speeds. Hope this helps. Nev

 

 

[skyfox1]

That's interesting skyfox1, are you saying that the pivot point and axle were to close to being perpendicular to one another, and moving the axle further to the rear of the pivot point solved the issue?Pud

Hi Pud yes if it trails behind it seems to stop it

cheers Geoff

 

 

[pudestcon]

Nev, we had a similar problem with the Citabria at Warnervale and it was put down to a sag in the rear spring that carried the tail wheel. The spring was either adjusted up or changed and the problem was fixed. This effectively changed the caster of the wheel to perpendicular to the horizontal exactly as you described.David

Gay asked me the question whether it was shimmying before 'exercising the undercarriage' as that may have caused a 'misalignment' so to speak - can't remember if it was or not now. I must confess I did not check the vertical alignment of the pivot point so I'll do that as well.

Pud

 

 

[sfGnome]

Pud,

 

I had a fairly close old stare at the earlier sections of the video, and I can't see any indication of tail wheel wobble until after the landing. Granted, they weren't close-up shots, but the wheel wobble was pretty obvious in the final section, so it should have been apparent earlier too. Perhaps you might get some additional clues from the bits of the video that hit the cutting room floor?

 

 

[pudestcon]

Pud,I had a fairly close old stare at the earlier sections of the video, and I can't see any indication of tail wheel wobble until after the landing. Granted, they weren't close-up shots, but the wheel wobble was pretty obvious in the final section, so it should have been apparent earlier too. Perhaps you might get some additional clues from the bits of the video that hit the cutting room floor?

Yep, I take your point sfGnome, and I've pondered that fact as well. The funny part is I've tried to replicate the shimmy at taxi before takeoff but can't do it. It only seems to start up on roll out at the end of a landing. Could have something to do with the speed at which the tail wheel comes down, that starts up the shimmy. Once started you have to be taxiing fairly slowly before it stops. Another point; I can vary the severity of the shimmy by varying the pressure on the tailwheel using the elevator. Once I even managed to stop the shimmy altogether.

 

Pud

 

EDIT: Stop the press! I just remembered that way back before first flight I did some taxi runs and the shimmy was there then - so not caused by the hard landing. No matter anyway, the problem is evident and I have to find a solution. Cheers

 

 

[skyfox1]

Hi Pud the shimmy varys with weight on tail wheel the more weight the less shimmmy its like a shopping trolly if you push it fast empty normaly one wheel will shimmy if you do it after it has a load it is not as noticeable.

 

l know this from watch the the wife shopping.

 

cheers Geoff

 

 

[Piet Fil]

Pud,

 

One potential source could be that the vibrations of the tail wheel at that speed are close to the natural frequency of the tail wheel springs. This could lead to an increase in oscillation and the closer it gets to the natural frequency it will increase the severity.

 

The springs you have installed may look very similar to other thruster spring sets, but there will be small variations in the natural frequencies between springs unless manufactured to strict tolerances. If you can beg, borrow or steal another set of springs and change them over, it will either confirm or rule out this cause. Alternatively you need to change their natural frequency by damping them somehow.

 

One interesting page on castor angle is http://mybearhawk.com/flying/shimmy.html

 

Also an excerpt from a Cessna page

 

"We have had some reports on Scott pneumatic tailwheels shimmying. The Scott 8" pneumatic tailwheel is designed with a friction type shimmy dampenenr. This friction is regulated by 3 small compression springs inside the upper casting. If the main king pin nut becomes too loose the shimmy dampener effect will be lost. When the shimmy occurs, it is recommended that the large nut be tightened in increments of 1/6 of a turn until the tailwheel starts to bind when rotated by hand. Then back off 1/6 of a turn for correct tension on the shimmy dampener. The king pin nut is on the underneath side of the lower housing directly above the tire. This procedure will definitely assure that compression springs in the dampener are acting against the friction dampener disc. We recommend a tire pressure of 30 pounds on both the 140 and 170 for the 8" pneumatic tailwheel. When connecting the springs and chains on this assembly, it is recommended that the stretch in the springs be from 1/8 to 1/4". The springs used with the 3200 assembly have a high tension rate and if stretched to any extent on assembly the mechanism may not release easily. No slack should be left in the chain and spring hook-up when both sides are connected."

 

Just some thoughts and I hope they help

 

Phil

 

 

[pudestcon]

Thanks Guys,

 

I found that link particularly helpful Phil.

 

Pud

 

 

[pudestcon]

Here is the link to the video of my first flight in GayGirl, taken from the cockpit on a Flip Mino camera, not the best footage with the camera not setup quite right but you'll get the idea.You'll notice my management of the aircraft is very rusty (notice the revs I had to pour on, as a consequence of poor selection on base, to find the strip), but it's all coming back to me now with more and more hours in the air.

Pud

 

 

[Powerin]

Hi Pud the shimmy varys with weight on tail wheel the more weight the less shimmmy its like a shopping trolly if you push it fast empty normaly one wheel will shimmy if you do it after it has a load it is not as noticeable.l know this from watch the the wife shopping.

cheers Geoff

Shimmy stops when you ride in the trolley Geoff?

 

 

[winsor68]

Jeez Pud I like those videos!!! I am hoping to do my Thruster Endo (TW and LP) soon!!! Definately going to ask Santa for a Thruster!

 

 

[pudestcon]

Cograts Pud, told you you would beat me, Ole can't even get mine out of the hanger without covering it in mud at present.Cheers Scotty

Well I've been waiting on you announcing the big event Scotty, but nothing........ I hope the weather clears up soon so you can get in the air.

Pud

 

 

[pudestcon]

Jeez Pud I like those videos!!! I am hoping to do my Thruster Endo (TW and LP) soon!!! Definately going to ask Santa for a Thruster!

Yeah I like the Thruster; not the prettiest aircraft you've ever seen but within the budget, and it tests your flying skills in it's own way. A bloody fun aircraft to fly around on a lazy Sunday morning.

I'm working on editing another video at the moment which is similar to the 2nd video I put up - all from the cockpit but a slightly different camera position which gives a not-entirely-accurate perspective. It looks like I'm heading for the deck at rather a steep dive, at times. At other times it shows my approach as being off line when I reckon I've got it nailed. I'm just gonna keep experimenting with the camera and working on my flying skills until I know it's right.

 

Pud

 

 

[pudestcon]

Steve and I checked out the tail wheel today to see if we could nail the cause of the shimmy. The photos here show the tail wheel assemblies on all 3 Thrusters in the hangar - I must confess I don't see any difference to the castor angle on any of them (other minor differences are evident), with only mine having the shimmy. See what you think.

 

 

 

 

The flat tyre on mine was a bit of a surprise this morning but no matter, soon have that sorted. I removed the tail wheel assembly from the aircraft and dismantled it to find one of the bearings completely shot. I didn't install the tail wheel so I'm not sure what condition the bearings were in at the start. I'll be replacing both bearings anyway this week. I'll also straighten the spring assembly as both leaves have a slight curve contributing to the sagging pivot point giving negative castor. I'll also make up some shims out of chrome moly steel to go under the lower spring clamp fixing the assembly to the tail structure, just in case I need them to give positive castor on the pivot point.

 

Pud