Does anyone know the meaning "Tumbling" in aircraft motion?

[Otyanomizu]

Hello everyone!

I'm reading wind tunnel tests reports of the McDonnell XP-85, but there is part I can't understand.

Were written "tumbling" or "tumbling characteristic" in some page in this reports, what mean "tumbling"?

Reports can read in this Nasa technical reports server : Free-Spinning and Tumbling Tests of a 1/16-Scale Model of the McDonnell XP-85 Airplane - NASA Technical Reports Server (NTRS)
Rink : https://ntrs.nasa.gov/api/citations/20050028500/downloads/20050028500.pdf

Image is draw a red line under the written "tumbling" in top page in reports.

 

[Wurger]

tumble ... generally - the aerobatics / acrobatics IMHO. But I may be wrong.

but also ...

- loosing of the balance
- disarrange
- put into disorder by or as by tossing here and there
- move in an uncontrolled way, as if falling or likely to fall
- tipped or slanted out of the vertica
- an acrobatic feat of rolling or turning end over end
- roll over and over, back and forth
- rotating about an axis transverse to the apparent wind, not necessarily horizontal
- a sudden drop from an upright position
- fall quickly and without control
- fall suddenly and sharply
- fall, especially in a helpless or confused way
- fall or decline suddenly, as from power, altitude, etc
- fall down quickly and suddenly, especially with a rolling movement

 

[cvairwerks]

Tumbling in the report means that the a/c will not rotate in an uncontrolled form about the pitch axis....ie it won't try to swap nose for tail in pitch.

 

[pbehn]

If you have a gun in the nose of an aircraft and use all the ammunition the CoG moves backwards making the aircraft unstable and prone to tumble, this happened on the P-3 AAAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhh I nearly went to the dark side.

 

[rochie]

If you have a gun in the nose of an aircraft and use all the ammunition the CoG moves backwards making the aircraft unstable and prone to tumble, this happened on the P-3 AAAaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhh I nearly went to the dark side.

so, so close

 

[JDCAVE]

I think tumbling characteristics would be a measure of the tendency to "tumble" end over end. My believe is when incendiary ammunition was described as having a tendency to tumble, was because the bullets movement was "end over end".

Jim

 

[Engineman]

This report is related to the aircraft spinning behavior and the testing of a scale model in the vertical wind tunnel. There is a spinning film of the P39 that shows full scale spinning trials of the P39 and the commentary describes how it was proven that that aircraft did not tumble end over end in departures, despite having a somewhat variable spin behavior and even being encouraged with extreme forward stick and vertical attitudes at entry to the stall/spin, it did not tumble. Mind you, some of the spins were pretty violent.

Cheers

5port

 

[pbehn]

This report is related to the aircraft spinning behavior and the testing of a scale model in the vertical wind tunnel. There is a spinning film of the P39 that shows full scale spinning trials of the P39 and the commentary describes how it was proven that that aircraft did not tumble end over end in departures, despite having a somewhat variable spin behavior and even being encouraged with extreme forward stick and vertical attitudes at entry to the stall/spin, it did not tumble. Mind you, some of the spins were pretty violent.

Cheers

5port

From what I remember of discussions in the Groundhog thread the problems came when the guns ammunition was spent. In the trials you refer to the plane under test were ballasted.

 

[N4521U]

Would a V-tailed Bonanza tend to Tumble if it were to go into a stall?
I know they won't recover from a spin!

 

[Otyanomizu]

Tumbling in the report means that the a/c will not rotate in an uncontrolled form about the pitch axis....ie it won't try to swap nose for tail in pitch.

So, Does "Investigate tumbling characteristics" means "Investigate whether the aircraft has a tendency to rotate uncontrollably about the pitch axis (perhaps during a stall, etc?)" ?

 

[Engineman]

So, Does "Investigate tumbling characteristics" means "Investigate whether the aircraft has a tendency to rotate uncontrollably about the pitch axis (perhaps during a stall, etc?)" ?

I think I see what you are asking about, the definition of the term Tumble in the context. Your initial quote about the XP-85 model test seems to be an official write-up, and I think that you would have to refer to the definitions used by the writer. I have previously given you an example of a P39 test in an attempt to illustrate the term Tumble being used. I thought that fairly illustrated the term. However, you are still asking. So, here is a further example of an Aeronautical definition. You might notice that this definition makes no mention of being uncontrolled and does not include a specific amount of pitching motion.

Cheers

Eng




NASA (.gov)
https://ntrs.nasa.gov › api › citations › downloads

PDF​

30

by WJ Klinar · 1948 — Notion defined as merely a tumble consists of a pitching motion about the Y-axis. NACA. •. CONFIDENTIAL. Page 18.

 

[Otyanomizu]

I think I see what you are asking about, the definition of the term Tumble in the context. Your initial quote about the XP-85 model test seems to be an official write-up, and I think that you would have to refer to the definitions used by the writer. I have previously given you an example of a P39 test in an attempt to illustrate the term Tumble being used. I thought that fairly illustrated the term. However, you are still asking. So, here is a further example of an Aeronautical definition. You might notice that this definition makes no mention of being uncontrolled and does not include a specific amount of pitching motion.

Cheers

Eng



View attachment 713731
NASA (.gov)
https://ntrs.nasa.gov › api › citations › downloads

PDF​

30

by WJ Klinar · 1948 — Notion defined as merely a tumble consists of a pitching motion about the Y-axis. NACA. •. CONFIDENTIAL. Page 18.

Thank you Mr. Engineman. I'm sorry for my ignorance and illiteracy.

I could understand about word "Tumbling" by your explanation.

Cheers

 

[JDCAVE]

Two other terms to describe motion include "pitching" (in the vertical plane) and "yawing" (left right in the horizontal plane).