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ESDU Challenge: Parachute Decelerator

Posted August 29, 2014 12:00 AM by SavvyExacta
Pathfinder Tags: ESDU

In this series from IHS ESDU, challenge questions will be posted for the community. Some questions may require calculations and others are general knowledge questions.

Here's this week's question:

Which type of parachute would be suitable as an aerodynamics decelerator to reduce an aircraft's landing role?

a. Conical(solid fabric)

b. Hemispherical (solid fabric)

c. Conical (ribbon)

And the answer is:

c) conical (ribbon). Only designs with high levels of geometric porosity can deliver the stability requirements of this application. See ESDU 09012 for more information.


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#1

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 12:30 AM

This one works pretty well.....so b.

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#2

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 3:18 AM

Landing roll, not role.

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#3

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 3:30 AM

This is really a question about the role of grammar and proof reading in publishing, right?

For my money, anything that hangs off the back and catches wind will sloe the aircraft down.

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#4

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 8:54 AM

I think the choice is the conical ribbon as it has the highest coefficient of drag (.5 to .55) over the other choices.

However, there is something called a ring-slot conical that has even a higher C/D, but I don't know why they are not as popular as the choices you mentioned. Maybe it has to do with size.

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#5
In reply to #4

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 12:03 PM

Well, as the drogue chute is deployed at a fairly high speed, a high cd isn't usually desirable. The 'chute is intended to burn off some of the speed so brakes can be applied.

I'm going with answer a.

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#6
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Re: ESDU Challenge: Parachute Decelerator

08/29/2014 12:56 PM

You could be right, but the straight conical chute has a lower C/D for a given size.

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#7

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 4:15 PM

Whatever type is used, It is important that all seatbacks be returned to the upright position and seatbelts are securely fastened.

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#8
In reply to #2

Re: ESDU Challenge: Parachute Decelerator

08/29/2014 6:23 PM

Well, if the parachute is big enough, the plane won't have to land, so that reduces its landing role.

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#9

Re: ESDU Challenge: Parachute Decelerator

08/31/2014 8:05 AM

They are all suitable! They are not equally effective though.

Perhaps you were attempting ask which is the most effective.

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