2H4
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Airframe Modifications

Tue Feb 27, 2007 2:42 am



I ran across this photo:


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Photo © Koen Hartkamp



....and started wondering....would a large window like this be able to withstand the pressurization that is typically placed upon this airframe, or might this particular aircraft have altitude/pressurization limitations placed upon it?

If windows like this can be installed without any performance limitations, I would think that, properly marketed, a fair number could be sold to owners/operators who might enjoy the view.


2H4


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miamiair
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RE: Airframe Modifications

Tue Feb 27, 2007 2:52 am

Quoting 2H4 (Thread starter):
If windows like this can be installed without any performance limitations, I would think that, properly marketed, a fair number could be sold to owners/operators who might enjoy the view.

That's what Supplemental Type Certificates (STC's) are for. Military aircraft use different certification procedures, as civil regulations may not apply. The Coastie Falcons have those as well.
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aeroweanie
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RE: Airframe Modifications

Tue Feb 27, 2007 3:33 am

The U-125A aircraft might be limited in terms of ceiling, to reduce loads on the observation window. A check of the Type Certificate Data Sheet provides the following:

NOTE 49. Raytheon Corporate Jets, Inc. Modification 25AB047A introduces the Hawker 800 intended for operation by the Japanese Self Defence Agency as a U-125A aircraft. An RCJ document, ref. CJE.CPD.D.272.001383 Issue 1, outlines the changes made to a standard Hawker 800 aircraft to achieve the delivery standard exported from the manufacturer. This modification was approved by the UK CAA on December 7, 1994 and is accepted by FAA as having demonstrated compliance with the particular requirement of the customer. Where provisions have been made for the fitment of equipment by the Japanese customer, these have been shown to comply with the associated installation requirements and be of no hazard to the aircraft, but have not been investigated for their intended function. Aircraft manufactured under this Type Certificate are eligible for export once they have been found to conform to the specification outlined in RCJ document ref. CJE.CPD.D.272.001381 Issue 1.

A Hawker 800 aircraft modified as specified above must be operated in accordance with the approved Airplane Flight Manual Doc. No. HS.1.16 containing Particular Amendment No. P/64 and any other applicable approved amendments.”
 
PurdueAv2003
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RE: Airframe Modifications

Tue Feb 27, 2007 11:33 am

The load carrying capabilities of the fuselage with a larger window will be reduced, but maybe not as much as you might think. If the width of the window remains the same while the length is increased, the load capabilities in the hoop direction will remain essentially the same. There will only be a decrease in the load carrying capabilities in the longitudinal direction. Depending on the original load capabilities vs actual applied operating load, there could be a reduction in the maximum operating differential pressure (causing a reduction in the operating ceiling). If the actual operating loads are less than the ultimate load capability by a large enough margin, you might not have to reduce the ceiling at all.

To the reason of why you don't see large windows often, the major factor is cost. From the design standpoint, it would be easy to design larger windows into a new aircraft. Unfortunately, larger windows cost significantly more money, and the cost does not increase in a linear relationship to the size. Most operators don't want to shell out the extra money for a "luxury item".
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2H4
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RE: Airframe Modifications

Tue Feb 27, 2007 2:35 pm




Quoting PurdueAv2003 (Reply 3):
Unfortunately, larger windows cost significantly more money, and the cost does not increase in a linear relationship to the size. Most operators don't want to shell out the extra money for a "luxury item".

Well, not-so-insignificant amounts of money are spent on technologies to make cabins appear more spacious and open, so I suspect there might be an opportunity for someone to make some money on a large-window mod here or there....


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jetmech
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RE: Airframe Modifications

Tue Feb 27, 2007 2:53 pm

Quoting 2H4 (Thread starter):
....and started wondering....would a large window like this be able to withstand the pressurization that is typically placed upon this airframe, or might this particular aircraft have altitude/pressurization limitations placed upon it?

I have no idea if this particular aircraft has altitude of operational limitations, but I did find the large "bearskin" doubler around the cutout to be interesting.

Regards JetMech
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HAWK21M
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RE: Airframe Modifications

Tue Feb 27, 2007 3:10 pm

What Equipment is the Hump below covering.
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57AZ
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RE: Airframe Modifications

Thu Mar 08, 2007 7:00 pm

Quoting Miamiair (Reply 1):
The Coastie Falcons have those as well.

The USCG Falcons also have a hatch in the floor that can be opened in-flight. It is used to drop emergency rescue gear such as life rafts and bilge pumps to vessels in distress.
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