## Mission Segment Weight Fractions

## Mission Segment Weight Fractions

(OP)

Hello,

I'm currently reading Aircraft Design:A Conceptual Approach by Raymer. On page 31 there is an example of sizing calculations performed on an anti-submarine aircraft:

Mission Segment Weight Fractions:

1) Warmup and takeoff W1/W0 = 0.97

2) Climb W2/W1 = 0.985

3) Cruise R = 9,114,000 ft

C = 0.0001389 1/s

V = 0.6M x (994.8 ft/s) = 596.9 ft/s

L/D = 16 X 0.866 = 13.9

W3/W2 = e{-RC/VL/D} = e-0.153 = 0.858

Where would you perform iteration here until your only off by 1% of the desired weight? The aircraft is assumed to weight 10,000 lbs. Thanks.

I'm currently reading Aircraft Design:A Conceptual Approach by Raymer. On page 31 there is an example of sizing calculations performed on an anti-submarine aircraft:

Mission Segment Weight Fractions:

1) Warmup and takeoff W1/W0 = 0.97

2) Climb W2/W1 = 0.985

3) Cruise R = 9,114,000 ft

C = 0.0001389 1/s

V = 0.6M x (994.8 ft/s) = 596.9 ft/s

L/D = 16 X 0.866 = 13.9

W3/W2 = e{-RC/VL/D} = e-0.153 = 0.858

Where would you perform iteration here until your only off by 1% of the desired weight? The aircraft is assumed to weight 10,000 lbs. Thanks.

## RE: Mission Segment Weight Fractions

taking nothing from Dan Ramyer, and assuming your W3/W2 saying that travelling 9E6ft, = 2E3 miles, consumes "only" 15% of the weight of the plane; i'd say that doesn't make sense.

look at the fuel fraction of any large long range transport, fuel makes up something like 40-60% of the AUWt.

good luck with your project.

## RE: Mission Segment Weight Fractions

TTFN

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## RE: Mission Segment Weight Fractions

## RE: Mission Segment Weight Fractions

ASW Requirements

The key requirements for this mission for our hypothectical antisubmarine would be: the ability to loiter for 3 hrs at a distance of 1500n miles from the takeoff point. While loitering on-station, this type of aircraft uses sophisticated electronic equipement to detect and track submarines. For the sizing example, this equipment is assumed to weigh 10,000 lb. Also, a four-man crew is required, totalling 800 lbs. The aircraft must cruise at 0.6 Mach number.

L/D Estimation

For initial sizing, a wing aspect ratio of about 10 was selected. With the area of the wing and canard both included, this is equivalent to a combined aspect ratio of about 7. The author then gathered the wetted area ratio (Swet/Sref) from a chart in this chapter from historical trend(actually comparing this design to a Beech Starship)This yielded a wetted aspect ratio of 1.27(i.e., 7/5.5). Finally a maximum lift-to-drag ratio of about 16 was given(again from historical trend).

ASW sizing calculations

Mission Segment Weight Fractions(Britsh Units)

1) Warmup and takeoff W1/W0 = 0.97

2) Climb W2/W1 = 0.985

3) Cruise R(Range)= 1500 n.mi=9,114,000ft

C(fuel consumption)=0.0001389 1/s

V(velocity)=0.6Mx(994.8 ft/s)=596.9 ft/s

L/D(lift/drag)=16x0.866 =13.9

W3/W2=e{-RC/VL/D}=e-0.153 = 0.858

4)Loiter E=3 hrs = 10.800 s

C=0.4 1/hr = 0.0001111 1/s

L/D = 16

W4/W3 = e{-EC/L/D} = e-0.075 = 0.9277

5) Cruise(same as 3) W5/W4 = 0.858

6) Loiter E= 1/3 hr = 1200 s

L/D = 16

W6/W5 = e-0.0083 = 0.9917

7)Land W7/W6 = 0.995

Can be found as a worksheet from the following:

http://www.aircraftdesign.com/ASW.xls

Thanks.

## RE: Mission Segment Weight Fractions

2) the problem answers your question ... when your guess (B21) equals the calculated result (B35) you're finished.

3) "they" frown on student posts

## RE: Mission Segment Weight Fractions

## RE: Mission Segment Weight Fractions

and thx for the star !

## RE: Mission Segment Weight Fractions

TTFN

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## RE: Mission Segment Weight Fractions

## RE: Mission Segment Weight Fractions

I'm not sure about some of your assumptions, take a look at what the S3 did, or even the Tracker, even allowing for newer materials & smaller electronics, I'm not sure you mass makes sense, depending what mass it is.

http://en.wikipedia.org/wiki/S-3_Viking

KENAT,

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