Wheel Spats - Are they worth the trouble?

[Guest russ.mullins]

I would like to ask anyone out there for an opinion on whether the benefits of wheel spats outweigh the inconvenience. I have no real knowledge on this subject other than to have noted that the wheel spats make a plane look prettier, and keep the sheep poo off the underside of the wing when I use a farm strip, but I don't know whether they really save any fuel by making the plane more aerodynamic, or slow the plane down much. I do know that they are a real nuisance when I'm checking tyre pressures and wheel/brake condition, and they sometimes get knocked about on rough ground, and they sometimes get full of mud(and sheep poo) when the dirt strip is a bit damp, and they tend to make the brakes get hotter. So if anyone has done the maths, or tested their plane with and without wheel spats, I'd love to hear their findings.

 

 

[David Isaac]

No not if you are frequently using sheep poo as your landing ground or any poo for that matter for all the reasons you have stated.

 

They may add 3 to 5 knots to your cruise speed if properly fitted, but they add weight which increases with each landing in sheep poo, they are hard to clean, they make preflight inspections more difficult ... oh and they cost a lot and damage easily on rough fields. I don't have them on my aircraft and wont fit them either, but I rarely land on bitumen and sheep and cow poo is an issue for me as well. But that is all just my opinion buddy, there may be other views on this.

 

 

[facthunter]

Mud is more of a problem than poo. You guys have covered it with the difficulty of checking tyre pressures and working on the wheels etc They look nice though Nev

 

 

[Methusala]

I installed them on my VP-2 and I think they, 1) Looked good!; 2) Did nothing for airspeed in cruise ; 3) added weight, and ; 4) caused problems on the ground.

 

 

[Guest russ.mullins]

I'm wondering whether anyone has ever tried a kind of flat mudguard above the wheels to stop the mud (or poo) splattering onto the bottom of the wings. I guess with a high wing its no problem. I think I would happily sacrifice looks and airspeed for the ability to check my wheels, tires and brakes without hassles if I could just stop the flying mud and poo sticking to the wing

 

 

[Guest davidh10]

I suspect it depends on the aircraft. I've heard that on some they change the flight characteristics significantly, while on others it is marginal. On the Airborne trikes, the fin on the wheel spats is used to reduce pod yaw in addition to any reduced parasitic drag.

 

I am usually only landing at aerodromes, but on one occasion at a rather wet farm strip (couldn't use brakes without skidding), I did get the spats filled with mud. It was quite difficult to get it out, so can appreciate your predicament.

 

 

[Guernsey]

I've recently seen a brand new Foxbat with Tundra Tyres fitted with metal mud guards set horizontally on a frame just behind the wheels, seemed like a good idea.This aircraft was temporarily housed in our hangar on its way to an SA country customer.

 

Further to the problem with mud etc, this can build up under the spat on take off then dries hard in flight and can seriously clog up your wheels and prevent them turning on landing. This of course depends on the amount of clearance you have between the spat and the wheel.

 

Recently we had a puncture in the front wheel of the Morgan Sierra and as the nose dropped, the spat was damaged, we have since repaired it and mounted the spat higher.

 

The Sierra looks magnificent with wheel spats however if it was my aircraft I would remove them. Safety before looks I say.

 

 

 

[J170 Owner]

I would like to ask anyone out there for an opinion on whether the benefits of wheel spats outweigh the inconvenience. I have no real knowledge on this subject other than to have noted that the wheel spats make a plane look prettier, and keep the sheep poo off the underside of the wing when I use a farm strip, but I don't know whether they really save any fuel by making the plane more aerodynamic, or slow the plane down much. I do know that they are a real nuisance when I'm checking tyre pressures and wheel/brake condition, and they sometimes get knocked about on rough ground, and they sometimes get full of mud(and sheep poo) when the dirt strip is a bit damp, and they tend to make the brakes get hotter. So if anyone has done the maths, or tested their plane with and without wheel spats, I'd love to hear their findings.

The spats on my Jabiru weigh 'nothing'. The greatest advantage is that they stop dirt, stones and mud being flicked up all over the wing and especially the tail plane. Use them if you have them.

 

 

[fly_tornado]

best of both worlds?

 

 

 

[David Isaac]

Now that is a clever idea, won't stop the mud but solves the inspection problem and reduces drag.

 

 

[Guernsey]

It does look like a good idea however, not wishing to sound negative, would it reduce drag.

 

The airflow would continue to flow around the wheel on both the top and the bottom remaining close to the tyre surface and then would flow into the spat causing drag unless there was an opening of some sort on the bottom of the spat to release the pressure without that it would still collect mud.

 

I couldn't find the specific article on the website provided but will keep looking.

 

Alan.

 

 

[Neil_S]

best of both worlds?

Hi FT - that looks good. A bit like mudguards on a pushbike - stops the worst of the mud but still allows decent inspection of tyres and brakes. Also good for a bit of drag reduction (maybe).

 

A mate of mine who owns a Jab 160 reckoned his spats collected a few kilos of mud, so he took them off....

 

Cheers

 

Neil

 

 

[Bryon]

Guernsey and David,

 

have a look at the photo, from the way the half spat is mounted and curves around the wheel, it looks like the bottom of the spat is open.

 

If that is the case, it would work well

 

All you need to do is paint the wheel hub blue to match it

 

 

[Guernsey]

Gee Bryon, you could well be correct, I'm going to do some more investigating because my youngest Son is somewhat of an expert on fibreglass.

 

If it is open at the bottom though, this could cause a lot of drag at high angles of attack.

 

Alan.

 

 

[Jabiru Phil]

I guess that a rag wing or tail could be more easier damaged by flying sticks etc without spats

 

I have taken mine off the Jab when touring outback strips as gibbers and wet clay cause damage

 

I put them back when I get home.

 

I have not noticed any speed difference as it is too minor to tell, but I have been told about 2-3 kn. max

 

Phil.

 

 

[fly_tornado]

more detail.

 

 

 

[Guernsey]

Couldn't open it FT.

 

 

[Guest Andys@coffs]

On my 230 they make a 120kt cruise 110-115kts. Practically that translates to an extra 1/4hr every 3hrs. To me, when Im doing long distance I put them on, when im just mucking about locally I leave them off. (In other words mostly off)

 

I have had a front spat and a rear spat cause me grief now on landing when the spat has rotated due to aluminium failure due spat vibrations causing fatigue cracking. Inspection of that aluminium is only possible with the spat off, and is one of the reasons that the mounting methodology was changed by bundaberg some time ago. The aluminium that is used on mine is about a 15cm piece of U tube where the bottom is flat nor rounded (open square). It always cracks at the corner.....

 

Having a rear spat rotate is like landing with a brake 1/3 on, on one side, (only 1/3 because the fibreglass skids, whereas rubber does too, but with a much greater grab on the bitumin, life becomes very challenging once you run out of rudder authority.....

 

Andy

 

 

[old man emu]

The Piper Tri-Pacer has a flat plate mudguard over the nosewheel, so I suppose something similar over the mains would deflect mud and water spray.

 

I think that the generally accepted speed gain when spats are fitted is about 3-5 kts, so you have to calculate the value in terms of fuel saved -vs- any additional maintenance time resulting from their being fitted.

 

OME

 

 

[Yenn]

A lot depends upon the speed of the plane. Putting spats on a Thruster woule only be useful for control of cow dung. On my starlet it gives me about 4kts and the side of the spat is open beside the wheel for access. A bit like the photo above with a front and back section in place. I will not be fitting spats to my new RV4 when it first flies, but the reason is to add drag and assist in the break in of the new engine. On a plane which is as fast as the RV there is a considerable drag reduction with spats.

 

 

[Guest russ.mullins]

This forum is a great place to learn from others peoples experiences. The spats on my Cheetah are great for keeping the mud off the wings and tail but they are a right pain when it comes to anything else. I've had a fewmain wheel punctures and I attribute that to low tire pressure because most punctures have been a pinch injury or a tube failing to grip the tire when it hit the tarmac and tearing the tube at the valve. It's my own fault for not checking the pressure every time I fly, and it's one of the reasons I'm keen to remove the spats for good. Problem is that whenever I do remove them the wings get covered in mud if the strip is a bit damp, or worse yet some sheep poo flies up and that stuff sticks like poo to a blanket. I'm probably as diligent as anyone when it comes to pre flight inspections, but up until the spat (pardon the pun) of punctures I didn't remove the spats every time I flew to check tires, brakes and fixtures. I'm keen to investigate the mudguard option more, perhaps a simple aluminum plate above and below the main wheels to catch mud might solve everything.

 

 

[poteroo]

On a flying school J-160 we have removed the spats for reasons of weight, blocking with debris,access to tyre valve,and tyre inspections. It makes about 3 kts difference in IAS, and nothing really in climb. Better for student training.

 

If you happen to own a 'real' paddock aircraft like a Cub, C170,C180,C185.... then rejoice in the fact that, while you'll get a bit of sheeps or cows under the wing, you'll get up and away. Oversize tyres seem to reduce it..... lower RPM? Apply brakes immediately after liftofff to reduce the dung being flung!

 

On an RV, the wheel spats and leg fairings make about 10-15 kts difference. Fit them after you've done the initial engine run in... (as noted by Yenn). They are a pain when using an RV out of paddocks - but luckily the performance is so good that you don't have to roll through too much. Use flaps for t/o and you'll be levitating at <40 kts.

 

happy days,

 

 

[XP503]

I put them on my drifter to stop mud/ grass/crap going ALL over the aircraft, plus Im sure theyve stopped a few little stones going through the prop too...maybe??

 

Looks ten times better with them on but of course makes no difference to speed.

 

 

[pudestcon]

Perhaps we need retractable spats that can be activated same time as flaps. Don't ask me how they would operate, where they would be stowed, or anything else for that matter. I just came up with a numbskull idea - up to you guys to figure it out!!! Can it be done?

 

Pud

 

 

[Guest davidh10]

As tyres tend only to go flat on the bottom, I don't see how they stop you checking tyre pressures. You can usually judge pretty closely by visual inspection, without need of a tyre gauge.