WHAT ARE THE SPEED FACTS ON SPATS?

[Captain]

Does anyone have any accurate or factual tests of the performance of their J (any type will do) with and without spats?

 

 

 

What I am looking for, if possible, is:

 

 

 

1 With & without all three.

 

 

 

2 All 3 on vs the 2 removed from the main gear (nose spat still on).

 

 

 

Hope someone can help on the above and if you want to add any other observations or your experience re spats they would be most welcome ................ particularly - if existing owners were to do a trip up thru the centre primarily via dirt strips would you leave your spats on?

 

 

 

Regards Geoff

 

 

[Wilfred]

We have no spats on the J200

 

The airfield we operate out of gets a bit sticky when it rains and it is easier to leave them off than battle with them when they clog up with mud.

 

There is no measurable difference in speed without them. There are claims of between one and three knots difference but we have been unable to note a measurable difference . We even put them back on one day to try some tests over the same conditions and no real difference. I guess its pretty hard to pick up a knot or two difference on your instruments.

 

They (all three) have been off now for over a year and they are tied to the wall in the hanger and will only go back on when we sell the aircraft.

 

 

[BigPete]

I too am pantless (look Ma no spats!)

 

Doesn't seem to make any difference (J160c) I'm cruising at 2800 revs and about 92/93 knots ASI.

 

regards

 

 

[Guest brentc]

I think there was a couple of knots in it on my J400, but no more.

 

Where I did notice the difference was the aircraft felt like it was 'hitting the wall' at the higher speed and wouldn't go any faster.

 

For example, if I pushed the nose forward it was hitting the wall at 130 knots, but with them on it was hitting closer to 140 with relative ease.

 

It was only really noticeable when fiddling around in anything other than straight and level flight.

 

I've had the rears off quite a few times and haven't noticed much difference however I can't help but feel that they slow me down.

 

The trick is to attach them with around 8+ screws with fixed locking nuts. Placing foam inside the back just behind the tire and glassing it in will help also. The Jabiru original ones have a tendency to split down the middle if you haven't joined them well enough.

 

There are 6 sets lying around at the school at Tooradin as they can't stand up to training there on the bitumen so I'd hate to see what gravel might do.

 

 

[Guest Biggles1]

Determine whether you want a LITTLE more speed or a lot more convenience.

 

You are all right. At the higher speeds they make a difference. On a C206 (300hp) they made a difference of 7kts at a cruise speed of 135Kts. So you have to determine what you are going to use your aircraft for - cross country or chooffing around. In the main, the trouble they cause, (mud, bukkdust, tyre inspections, falling apart and mending punctures) they are not worth worrying about them. I was a bush pilot, so I'm talking from experience (Birdsville Marree Andamooka Coober Pedy etc) and if I was going in a Jab I'd leave them home.

 

It is the same as taking the hubcaps off your car, or putting on white wall tyres - look good, do nought! Brentc's gought the right idea but you'll leave your with Lassiter.

 

Biggles1

 

 

[Geoff]

I agreed with Biggles1, Geoff. good for looks no good in the Bush

 

 

[Guest DonC]

On my J230 at 2850rpm 120 kts true on - 117 kts true off

 

 

[Captain]

Thanks to you all for your replies. That is exactly what I was after.

 

 

 

As I'll be operating off a farm strip here, albeit a pretty good one, they'll be off.

 

 

 

Guess I can turn up a shorter aluminium keeper-bush for the end of the axles if the spats are not required. It could then maybe take the item as per the PS below.

 

 

 

Looks like you need to put your avatar thru photohop Pete .... to make it pantless there.

 

 

 

Regards & thanks again

 

 

 

Geoff

 

 

 

PS there was an article on the UK J site about a circular fibreglass cover over the outside of the rim which they claim makes a goodly difference ........... maybe that would get a speed result somewhere between clothed and naked without the hastles. Has anyone tried that?

 

 

[Geoff]

Big Pete may be able to shed some light on this, as he has them fited

 

 

[BigPete]

Guys - I was disappointed in the quality - cost me around 150 aussie dollars including freight. Make your own either 'glass or spun aluminum.

 

 

 

[Captain]

Peter

 

What did they do to speed?

 

 

[BigPete]

Captian - boy your quick - as far as I can tell NOTHING.

 

But it looks good.

 

regards

 

 

[Captain]

OK .... thanks again