D5 tow-ball weight - can this be true?

Quote:

---

Originally Posted by MR LR

Planes are an alloy monocoque, have been since they stopped making them from timber and canvas, not too many of them fall out of the sky, and they have huge amounts of flexure in their frames, particularly the wings.

Fatigue is only an issue with poor design.

---

The timber airplanes were also monocoques really - one might say wooden space frames I guess.

The DC4 followed the reliable DC3 - the DC4's tails would drop off. The Electra plain that our Air Forces still use for radar tracking / defence (being replaced though) - also their tails would fall off. My Mum flew DC4's to Vancouver, from Melbourne. It took her a week. My dad flew Typhoons and Spitfires in WWII.

As far as alloy goes - it really does fatigue. Just ask a racing yachtsman, who uses an alloy mast. These fatigue. An example is a close friend of mine - Hugo Ottaway from Insail in Melbourne. He races a J24, an international small racing keelboat. He has been to many world championships, representing Australia. He replaces his costly alloy mast regularly - because the mast moves or flexes, in order to control the sail shape. And when it moves, it fatigues, it hardens. This results in it loosing its elasticity - and its "spring". This slows the boat down. So he replaces his masts, because its necessary. This all happens because aluminium really does work harden.

Meanwhile steel is much less subject to work hardening. Caste iron itself suffers this issue much less than steel. Perhaps why our Lr's still use a high spec chrystalline or compacted / vermicular graphite iron for their V6 engine blocks. While lesser loaded motors use aluminium. I am guessing iron is better than alloy in a high load diesel engine. I think due to good design.

I don't know of any alloy chassis based vehicle.

For towing, I'd rather the vehicle weighed 150kg more, and had a chassis. And I'd be worried about it having an alloy chassis. Without towing or doing off road stuff, an alloy monocoque and also composites, promise much more efficiency. The new RRS is heaps better for most people. 90K for the base model seems great value too IMO. But I suspect for my usage, its not as good.

Quote:

---

Originally Posted by Melbourne Park

The timber airplanes were also monocoques really - one might say wooden space frames I guess.

The DC4 followed the reliable DC3 - the DC4's tails would drop off. The Electra plain that our Air Forces still use for radar tracking / defence (being replaced though) - also their tails would fall off. My Mum flew DC4's to Vancouver, from Melbourne. It took her a week. My dad flew Typhoons and Spitfires in WWII.

As far as alloy goes - it really does fatigue. Just ask a racing yachtsman, who uses an alloy mast. These fatigue. An example is a close friend of mine - Hugo Ottaway from Insail in Melbourne. He races a J24, an international small racing keelboat. He has been to many world championships, representing Australia. He replaces his costly alloy mast regularly - because the mast moves or flexes, in order to control the sail shape. And when it moves, it fatigues, it hardens. This results in it loosing its elasticity - and its "spring". This slows the boat down. So he replaces his masts, because its necessary. This all happens because aluminium really does work harden.

Meanwhile steel is much less subject to work hardening. Caste iron itself suffers this issue much less than steel. Perhaps why our Lr's still use a high spec chrystalline or compacted / vermicular graphite iron for their V6 engine blocks. While lesser loaded motors use aluminium. I am guessing iron is better than alloy in a high load diesel engine. I think due to good design.

I don't know of any alloy chassis based vehicle.

For towing, I'd rather the vehicle weighed 150kg more, and had a chassis. And I'd be worried about it having an alloy chassis. Without towing or doing off road stuff, an alloy monocoque and also composites, promise much more efficiency. The new RRS is heaps better for most people. 90K for the base model seems great value too IMO. But I suspect for my usage, its not as good.

---

I understand the engineering side of it quite well... and I didn't say fatigue and hardening didn't exist, even with steel it exists.

BUT, good design can engineer fatigue factors out to a point that they will not be reached in a machines reasonable lifespan. As you alluded to with DC4 vs. DC3.

The alloy chassis would not be a factor in the tow ball down load, it's plenty strong enough.

Quote:

---

Originally Posted by Melbourne Park

Maybe I will ring my dealer and ask.

But I have been using Land Rover Australia stats for 2017.

I have been referring to page 96 of the E brochure for the L494 Range Rover Sport Australian edition. Downloadable from here:

page 96: Technical Details
TECHNICAL SPECIFICATION, PERFORMANCE AND KEY DATA

Unfortunately the weights say 200kg ... which is better than what the media said in the UK, about the 3 litre SDV6, which had a reported maximum toe ball weight of only 150kg:
Range Rover Sport | Tow Car Awards

Concerning the hybrid, the current figures are published as being 150kg if the vehicle is loaded.

Perhaps there is an error from 2015 to 2017, or perhaps the 2015 data is not right????

---

I appreciate you downloaded that from the LR Aust site but it is the UK brochure - see the Local Supplement under (really an options pricing list) that but unfortunately it does not actually list the tow ball weight. Thinking about it logically why would the tow ball limit be downgraded for the 17MY compared to earlier versions.

The LR site also says this
"Range Rover Sport The Australian Range Rover Sport local specification sheet should be read in conjunction with Land Rover brochure Publication number: LRML 4905/15 (Range Rover Sport eBrochure), but it is important to note that Land Rover brochure LRML 4905/15 only represents a general global specification, and in the event of any inconsistency, the details contained within the Australian Range Rover Sport local specification sheet apply in Australia."

The same issue arose with the D3/D4 and equivalent RRSs. The Handbook lists ball weights much lower than 350Kg (I thing 150kg) but you had to go to the Aussie Supplement to see that the Aussie Cars had 350kg.

The current RRS is 350kg just as the D4 is (even though the basic handbooks say differently). With the D5 I am sure the same will apply - Uk around 150-200kg but in the Aussie Supplement will say 350kg. Certainly for the little engine D5 there may be differences but I am sure the full engine size - full 4wd versions will have a 350kg ball weight.

I think we are all getting bent around the axle about nothing - lets wait for the Aussie Supplements and then comment.

Garry

Quote:

---

Originally Posted by Melbourne Park

And I'd be worried about it having an alloy chassis.

---

The D5 has steel sub-frames, unlike the L494 RRS which has alloy sub-frames.

I don't believe the "tails fell off" any L-188 Electras (or the P3 derivative as used by the RAAF). [bigsmile1]

This is all sorted D5 spec is 3500kg and 350kg nose weight in Australian supplement.
Even has the right tag on tow bar stating this.

Quote:

---

Originally Posted by Hugh Jars

I don't believe the "tails fell off" any L-188 Electras (or the P3 derivative as used by the RAAF). [bigsmile1]

---

No. Actually it was the wings, in three accidents. Attributed by the Civil Aeronautics Board to a whirl mode resonance. Rectified by changing the engine mounts and some structural changes. This was done before any were operational in Australia, and before the Orion was in production.

I've always found it interesting that both the UK and USA managed, in roughly the same time frame, to develop a very successful maritime patrol aircraft from a disastrously accident prone airliner (Electra -> Orion, Comet -> Nimrod).

The Comet was the first turbojet airliner, and the Electra was the first US turboprop. In the Comet, the fuselage broke up as the result of a poor understanding of fatigue, and the Electra the wings fell off because of a poor understanding of vibration modes. Both represented a major increase in operational speed.

Quote:

---

Originally Posted by JDNSW

No. Actually it was the wings, in three accidents. Attributed by the Civil Aeronautics Board to a whirl mode resonance. Rectified by changing the engine mounts and some structural changes. This was done before any were operational in Australia, and before the Orion was in production.

I've always found it interesting that both the UK and USA managed, in roughly the same time frame, to develop a very successful maritime patrol aircraft from a disastrously accident prone airliner (Electra -> Orion, Comet -> Nimrod).

The Comet was the first turbojet airliner, and the Electra was the first US turboprop. In the Comet, the fuselage broke up as the result of a poor understanding of fatigue, and the Electra the wings fell off because of a poor understanding of vibration modes. Both represented a major increase in operational speed.

---

That is correct, JDNSW [smilebigeye] whirl mode resonance is a completely different animal to 'fatigue'....

Having square cabin windows didn't help the Comet, either [bigsad]

John.

Quote:

---

Originally Posted by Hugh Jars

That is correct, JDNSW [smilebigeye] whirl mode resonance is a completely different animal to 'fatigue'....

Having square cabin windows didn't help the Comet, either [bigsad]

John.

---

No, you have to wonder that the designers did not round the windows to minimise stress concentrations anyway - they did on the Comet 2, which was flying before the Comet 1 disasters. I wonder to what extent the problems related to the fact that when Comet design started, DeHavilland had never designed an all metal aircraft - and its aerodynamic predecessors (Albatross and Mosquito) were all wood, which is notably resistant to fatigue. (They had, though, during the war, built a lot of metal aircarft and parts to other manufacturer's designs - but I'm pretty sure none of these were pressurised.)

You need to remember that aircraft went from biplanes that peeked at 180-200 miles an hour to monoplanes that hit 350, later those same planes were hitting 460-470 in level flight and compression reversal in a dive and then jets,all in the space of 15 years or so.You can't expect designers to get everything right. Pat