Baroque
in service - 2 years
Posts: 3,991
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Post by Baroque on Feb 27, 2019 0:15:05 GMT 1
Wow, that IS a big engine! 22 inches or 56 cm more than the TXWB. I think it is doable on an A350-1000, but veeeeeery tight fit. ACAP shows 76 cm ground clearance from the engine (ignore the drain mast as that probably can be shifted elsewhere). I believe generally 40 cm is the lower limit for most aircraft but apparently there is no set rule (for comparison 737MAX is 43 cm). So if 50% of the difference can be accommodated by mounting it higher, you'll still have a clearance of 48 cm. Maybe some small modifications to the landing gear and tyres can increase the clearance a bit more. About the weight saving is it relative to a metal fan of the same size? I'm not sure if a bigger engine will weigh any lighter than the current one. |
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Post by stealthmanbob on Feb 27, 2019 0:18:23 GMT 1
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philidor
in service - 6 years
Posts: 8,950
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Post by philidor on Feb 28, 2019 12:23:38 GMT 1
Coming back from a two weeks trip,I found the above discussion very interesting, and I would like to chime in on two points.
1 - Market size for a possible Ultrafan-powered A350-2000. Baroque rightly pointed out upcoming widebody replacements, but Airbus must be aware of the market preference for relatively smaller aircraft. The main competitors to the new variant might be its smaller siblings, the Ultrafan-powered A35K and A359.
I agree that the new engine would greatly increase the odds of an A350-2000 being launched, but there would still remain a question mark, in my opinion.
2 - Engine diameter and engine to airframe integration. The fan diameter mentioned in the above discussion is that of the demonstrator. To re-engine the A350 family, Rolls-Royce would certainly offer a 'bespoke' variant exactly matching Airbus' requirements, so that I don't think there would be any problem there.
A final remark : if Boeing went on to launch the 797, and if Rolls-Royce was one of the engine providers, which Ultrafan variant would come to the market first ?
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backstroke
delivered!
Just an aerospace engineer with thirst for knowledge
Posts: 1,913 
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Post by backstroke on Feb 28, 2019 12:26:47 GMT 1
Wow, that IS a big engine! 22 inches or 56 cm more than the TXWB. I think it is doable on an A350-1000, but veeeeeery tight fit. ACAP shows 76 cm ground clearance from the engine (ignore the drain mast as that probably can be shifted elsewhere). I believe generally 40 cm is the lower limit for most aircraft but apparently there is no set rule (for comparison 737MAX is 43 cm). So if 50% of the difference can be accommodated by mounting it higher, you'll still have a clearance of 48 cm. Maybe some small modifications to the landing gear and tyres can increase the clearance a bit more. About the weight saving is it relative to a metal fan of the same size? I'm not sure if a bigger engine will weigh any lighter than the current one. The clearance that the engine must have is if you draw an angle between the point of contact of the tyre, the ground and the engine, that angle has to be more than 8 degrees |
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Post by marlibu on Feb 28, 2019 12:32:51 GMT 1
The wheel closest to the engine? Or the midpoint of a multi-axle bogie?
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backstroke
delivered!
Just an aerospace engineer with thirst for knowledge
Posts: 1,913
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Post by backstroke on Feb 28, 2019 13:07:30 GMT 1
The wheel closest to the engine? Or the midpoint of a multi-axle bogie? I'll have to check, but IIRC I think is the wheel closest to the engine. I will look for it this afternoon. |
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Baroque
in service - 2 years
Posts: 3,991
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Post by Baroque on Feb 28, 2019 14:47:30 GMT 1
The clearance that the engine must have is if you draw an angle between the point of contact of the tyre, the ground and the engine, that angle has to be more than 8 degrees Thanks backstroke. That's a nice bit of info. Can you illustrate this with a simple drawing? What is the point on the engine to which you connect the angle? |
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