math question

[jqavins]

The diameter ratio doesn't directly yield the transition length. Additional data, like transition shape or diameter change rate, is needed for its determination.

And that's what the 30:1 figure indicates, not the ratio of the diameters.

 

[Brandon.L]

I seem to have gotten confused. Is it correct that 'The diameter ratio can be a useful indicator in determining the length of the transition only if you also know additional data, such as the transition shape or the rate at which the diameters change? For instance, if you know that the transition has a cone-like shape and it's known that it decreases in diameter by 1/30 for every inch of length, then you can use this ratio to determine the length. But without this additional data, the diameter ratio alone won't give you an exact answer.

This topic was from my school days, so I remember it not very clearly.

 

[Brandon.L]

And that's what the 30:1 figure indicates, not the ratio of the diameters.

Perhaps I've just figured it out now

P.S. Heroyam slava!

 

[kuririn]

I don't believe that the 30:1 figure is related to the transition shape.
Just looking at it visually, the ratio of the two airframes being joined is nowhere near 30:1.
See posts 14 and 15.
I believe it relates to the exhaust gas expansion rate.

 

[Brandon.L]

I don't believe that the 30:1 figure is related to the transition shape.
Just looking at it visually, the ratio of the two airframes being joined is nowhere near 30:1.
See posts 14 and 15.
I believe it relates to the exhaust gas expansion rate.

Understood, it was a pleasure chatting with you. Thank you for your attentiveness and insights.

 

[jsdemar]

And that's what the 30:1 figure indicates, not the ratio of the diameters.

The 30:1 is like the pitch of a roof or stairway: "run" over "rise". Though, it's typically spec'd rise over run.
The edge of the cone, when aligned to it's center axis, has 1/30 as the tangent or 1.9 degrees.
It doesn't indicate the diameters or the length.
For example:

A, B, and C all have the same conic ratio or pitch. 1:30.
A and B have the same minor diameter but different major diameters and different lengths.
B and C have the same lengths but different minor and major diameters.

There are 4 parameters to specify the straight cone; you need at least 3 to define it!

 

[Brandon.L]

The 30:1 is like the pitch of a roof or stairway: "run" over "rise". Though, it's typically spec'd rise over run.
The edge of the cone, when aligned to it's center axis, has 1/30 as the tangent or 1.9 degrees.
It doesn't indicate the diameters or the length.
For example:
View attachment 635615
A, B, and C all have the same conic ratio or pitch. 1:30.
A and B have the same minor diameter but different major diameters and different lengths.
B and C have the same lengths but different minor and major diameters.

There are 4 parameters to specify the straight cone; you need at least 3 to define it!

You're most welcome for the explanation! TU

 

[Brandon.L]

Thinking back, I recall how our teacher would say during our lessons: 'Working on a transition for a build. To calculate the length of the transition, you can use the ratio of the diameters given. Since the transition is described as a 30:1 transition, it means that the diameter at the top is 1/30th of the diameter at the bottom.
P.S Just a reminder in case I've forgotten some details.

Thanks to you, I've already figured out this issue.