Noisy, rattling nose wheel .... what’s normal?

[Markdun]

I’m restoring a flood damaged (ex-Lismore) J200. Pretty close to flying stage, but I’m not used to those nose wheel thingos, particularly on a bumpy grass strips.  Seems to be quite a bit of knocking up there whenever I taxi fast over bumpy ground.  In my tailwheel aircraft I don’t even notice the bumps and any noise from the tailwheel is past history behind me... not so with J200 & with the short distance between the training wheel and the mains, the hobby horsing is unsettling.  It would be good to hear what is normal?   I’m thinking it’s clunking from the rubber doughnut stops.... can’t see where else it could be coming from.

[facthunter]

Any noise goes straight into the front bulkhead. Keep weight OFF the nosewheel whenever you can  with a Jab. nev

[APenNameAndThatA]

You’re not supposed to use the nose wheel for taxiing, 

[Markdun]

Ehhhh? When I did the conversion to nose wheel the instructor said to me as we were slowing down and about to turn off the runway (bitumen) that 'its ok for you to lower the nose wheel to the ground gently now'.  So if a nose wheel isn't for taxiing what exactly is its function; perhaps the same as a rubber duck?

[turboplanner]

I'd say the nosewheel mountings/fibreglass have been damaged. If all attachments are tight there will be no knocking; hard to diagnose what is loose if there isn't a black trail down from the suspect part, but you can use a long length of plastic tubing, mounting one end next to the suspect area and the other in your ear and do some taxying. 

Never taxy fast over bumpy ground because the prop doesn't have much clearance so easy for it to hit high spots and fracture.

 

[Markdun]

Thanks.  So no noise is too be expected from taxiing over bumpy ground.  Its all new & I assembled as per the manual.  I'll go over it again. There is a bit over 65kg there when the tanks are empty so the NW does carry a decent load.   

My airstrip is pretty good bump wise. The wombats seem to prefer drier spots; the wallabies just dig up the orchid tubers... tiny holes. Its the effing pigs. But the big problem ATM is too many soft muddy spots for a nose wheel aircraft. If the La Nina keeps up I just may have to stay with the conventional undercarriage aircraft in my hanger. 

[turboplanner]

1 hour ago, Markdun said:

Thanks.  So no noise is too be expected from taxiing over bumpy ground. 

Depends on your speed and how bumpy, and the next noise might be the prop shattering. Your honny horsing gives it away a bit, I've never experienced that in Jabs or any other nose wheel I've flown.  I've never subscribed to the theory of trying to keep the nose wheel off the ground when you're taxying, just landing on the mains then full back stick and just let the nosewheel settle on the ground as speed washed off; you shouldn't feel it touch. From there its taxying about walking speed  and making sure not to put the prop into a ridge in the Jab, or doing the flight planning for the next stage in a Warrior.

1 hour ago, Markdun said:

 

Its all new & I assembled as per the manual.  I'll go over it again.

If it was pulled apart after the flood look for something not quite right, like installing back to front; maybe it's not that, but you don't know if it had a nose-down landing in the past and slammed into the ground.

 

1 hour ago, Markdun said:

 

There is a bit over 65kg there when the tanks are empty so the NW does carry a decent load.

Some big people put that much weight on the front wheel of a bike, but 6g might change things.

1 hour ago, Markdun said:

My airstrip is pretty good bump wise. The wombats seem to prefer drier spots; the wallabies just dig up the orchid tubers... tiny holes. Its the effing pigs.

Pig rooting or cattle tracks in moist black soil will do it for you. Look how deep this one's getting in the photo

1 hour ago, Markdun said:

 

 

But the big problem ATM is too many soft muddy spots for a nose wheel aircraft. If the La Nina keeps up I just may have to stay with the conventional undercarriage aircraft in my hanger. 

 

[turboplanner]

Dragging a smudger over the pig rooting might be enough.

 

[Yenn]

I am not a Jab flier, but to me 65kg on the nosewheel sounds a lot. I have not found an aircraft that I couldn't lift the nosewheel a bit by lifting the prop, but 65kg would mean that the prop would be very hard to lift.

Check the POH to see what their weight and balance figures normally are. You may  need to do a W&B anyway as part of your restoation.

[turboplanner]

8 minutes ago, Yenn said:

I am not a Jab flier, but to me 65kg on the nosewheel sounds a lot. I have not found an aircraft that I couldn't lift the nosewheel a bit by lifting the prop, but 65kg would mean that the prop would be very hard to lift.

Check the POH to see what their weight and balance figures normally are. You may  need to do a W&B anyway as part of your restoation.

The prop is in cantilever, so you're not lifting 65 kg at the prop

[Yenn]

Turbs. Do you know what the recommended weights are for the J200. Even if the prop was twice as far away from the datum I reckon it would be hard to lift. I can't find the relevent numbers quickly. I think Jabiru use the leading edge of the wing as datum and I would assume recommended c of g would be about 300mm or so aft of that, or 25% of chord, so there would be a fair distance between nosewheel and c of g, all multiplying that 65kg.

[Markdun]

65kg on the nose wheel and 300kgs on the mains puts the CoG in a pretty good spot, though was a bit more overall than i would have liked. I don’t have the pre-flood W&B. If I did then I can figure how much mud I haven’t washed out, or whether it’s the Rotec LCH. Probably have to go 75kg to make it too nose heavy if I recall my CoG calcs correctly.

 

I can’t see how you could put any of nosewheel in backwards. 

[RFguy]

it's not hard to lift the J200/230 from the prop root . especially if you are tall.     I have no difficulty doing it. 

 

all sounds normal to me.

 

As you know Mark (others, we have discussed this privately) the configuration empty is pretty nose heavy , and not much more so with pilots. I think ur probably used to aircraft with narrow CG ranges (not 10-28% MAC) and it all feels a bit odd.  ha. and tailwheels.

 

Jabiru 200/230/400/430 weight varies considerably +/- 7 % with the fibreglass and paint application.  andif they've been pranged, the fibreglass gets heaped on.

My (bigger) J230  is 372kg, but some I looked at were 390/395kg at birth from Jabiru . 

 

[APenNameAndThatA]

65 kg sounds heaps to me. I am no expert. A Foxbat might be 20 kg. 

[RFguy]

J230 airframe #J 766 reg : 24-7597 factory : LHS 146.6kg RHS 148.4kg  , nose  72.5kg. tail ballast 1.3kg.

Edited August 29, 2022 by RFguy

[Blueadventures]

Nynja is Nose 78kg and mains 221kg

[Yenn]

I was obviously wrong about the nosewheel weight, surprised that it is so heavy, but that is no doubt the reason that nosewheels get damaged so often.

[facthunter]

Weight on the nosewheel depends on where the main wheels are located. The further aft the more % of the weight  on the nosewheel. Applying brakes throws more weight on the nosewheel while the plane is slowing down. or when thrust is applied with brakes on.  Nev 

[Blueadventures]

1 hour ago, Yenn said:

I was obviously wrong about the nosewheel weight, surprised that it is so heavy, but that is no doubt the reason that nosewheels get damaged so often.

It is not easy to keep the nose wheel up on the Nynja, like Nev says its to do with the main undercarriage axle location.  You will see the the Savannahs for example land and the nose wheel is easy to hold up; so their mains axle is further forward.  I have seen Savs low on fuel and loaded with cargo sit down on their tail; and this would be the lighter nose wheel weight and the mains axle pivot point and the mass of cargo behind the axle.

[turboplanner]

1 hour ago, facthunter said:

Weight on the nosewheel depends on where the main wheels are located. The further aft the more % of the weight  on the nosewheel. Applying brakes throws more weight on the nosewheel while the plane is slowing down. or when thrust is applied with brakes on.  Nev 

Correct, we're not talking about Flight W&B where calcs are about a datum, we're talking about mass distribution in the three wheels - defferent set of calcs.

 

[RossK]

Another Nose wheel wt reference point

Evektor Sportstar Plus  - 70kg on the nose wheel. 321Kg BEW

[RFguy]

17 hours ago, Blueadventures said:

You will see the the Savannahs for example land and the nose wheel is easy to hold up; so their mains axle is further forward.  I have seen Savs low on fuel and loaded with cargo sit down on their tail; and this would be the lighter nose wheel weight and the mains axle pivot point and the mass of cargo behind the axle.

even with flying W&B calcs good , if BOTH pilots got out mid air  it would very likely be tail heavy and unsafe.  *deadpan*

[RossK]

22 minutes ago, RFguy said:

even with flying W&B calcs good , if BOTH pilots got out mid air  it would very likely be tail heavy and unsafe.  *deadpan*

I hear Redbull are looking for pilots....🤣

[facthunter]

Didn't we just agree that the position of the mainwheels decide the weight on the nosewheel, predominantly?  W & B with no pilot is not required to be in the range but down to unusable fuel IS.  Nev

[RFguy]

It is fortunate that most small aircraft carry their fuel in a wing, or at least in a  tank  that is under the centre of lift, approximately. 

How big do the GA aircraft get before they have auxilliary aft and fore fuel tanks that significantly affect the CG ?

Wonder what some of the WW2 bombers felt like after letting go of the load.