Big tyres on Jabiru

[Guest Andys@coffs]

i dont recall , i assume its best case and expect worse performance for sub optimal like soft surfaces. anyway search for it on these forums as it was discussed previously in some detail as i recall

 

andy

 

 

[Spin]

http://www.avcom.co.za/phpBB3/viewtopic.php?f=59&t=52004

 

Link to the original South African discussion. The short story is that it is the result of quite a bit of comparative testing with several aircraft and on a hard surface. Feedback since it was published is that it is pretty accurate, but errs on the pessimistic side, ie. you may beat the figures with good technique.

 

 

[Wynand]

Using gravel or uneven grass surfaces quite often with my J430, I fitted 6" tyres, just like those used on C172 C182. I run them at 1.3 bar and can vouch that they smooth out the ride without impacting noticably on the flight.

 

 

 

[Guest Andys@coffs]

Is the picture recent?

 

I ask in that the oil cooler was changed some time ago to improve cooling (along with the increasing of the rear lower cowl lip and opening to improve the size of the exit vent for hot air. That change necesitated a changed cowl opening for the oil cooler. The opening you have is the older thin black one (Ithink) and in my J230 the change in cowl and cooler did improve cooling marginally, but then at the hot end anything in a downward direction is good....

 

Andy

 

 

[Wynand]

Hi Andy

 

This is a stock standard 2008 J430 by the Jab factory in South Africa. By then they'd added the lip at the bottom of the cowl. No overheating problems, even at ambient of 38°C. The following pic shows its mug more clearly, and the oversized tyres. Here, we'd landed on a pan, taking a break from the midday heat and associated turbulence in Botswana.

 

 

 

[bushpilot]

Hi Wynand,

 

Like the graphics there; it's a nice looking 430. I'm interested in the sliding section in your side window. Was it installed by the SA Jab people, or did you have it done? If the latter, do you know the brand? Would be very handy for photography work.

 

 

[Wynand]

Hi Chris

 

That photo window is on the pilot side.... heh..you a chopper pilot?

 

But you're right, in a way.

 

I should have put it on passenger side. I can only grip my camera with my right hand due the placement of the shutter button. That means I have to cross over my arms: Left hand on stick and right hand on camera. That causes terrible flying, bad pics and an irate passenger. Lately I've flown from the right seat so my passenger can take the pics. That sucks.

 

Jab in SA has someone local install various designs of photo windows. They look and work better than my DIY job.

 

 

[turboplanner]

Thanks for the replys. I supose I could spend a fair bit on the strip surface to achieve better performance.

$1000.00 for a B275 tractor, $800.00 for a Berends grader with wheel, $500.00 diesel for hundreds of passes, and some time.

 

 

[Camel]

Using gravel or uneven grass surfaces quite often with my J430, I fitted 6" tyres, just like those used on C172 C182. I run them at 1.3 bar and can vouch that they smooth out the ride without impacting noticably on the flight.

Hi.

Are the tyres fitted to original Jabiru rims and were any mods done to fit them. I take it the nose wheel is standard, does the plane sit lower at the front.

 

 

[Wynand]

Yes, the 6.00 - 6 tyres fit directly on the original rims. New tubes required.

 

Nose wheel is standard.

 

The bigger tyres raise the main gear axle stubs by 40mm. That translates to the prop being about 18mm closer to te ground.

 

The factory in SA does not endorse this owner mod, saying the brakes were not designed to stop the aircraft with such big wheels (mechanical disadvantage).

 

True, but I go lightly on the brakes and I can still stop in less distance than the take-off run required.

 

There is much less hammering on the gear legs over rough terrain and I'm sure the gear leg bolts are happier too.

 

Some pilots report noticably more drag in the air, but I've tested this and I can't measure any difference in IAS at same rpm and same DA.

 

 

The fellow in the hangar next to mine also fitted 6.00 - 6 's and added hub caps as supplied by SA factory. Nice!

 

 

 

[Camel]

looks good with big wheels and caps. Don't worry about the brakes they never were any good and if the wheel was smaller it wouldn't work any better I'm sure, I have used different pad material and have had better results but still can't rely on them for very long.

 

 

[frank marriott]

Better rotar discs avaible at Bunderberg [not Jabiru] and no break fade with more metal in the disc - I am sorry I cannot tell you where they sold as a friend of mine purchased them whilst doing his CASA to RAA conversion but have fitted them to 2 J230's and there is no break fade what so ever even on downwind landings on sealed surface.

 

FrankM