Looking for Igor Bensen's publication

[msmfi]

I'm currently looking for the following publication, by Igor Bensen:
Bensen, I.B., "Biased Cyclic Control for H-5 Helicopter", General Electirc Report No. R50GL174, 1-June-1950
I would appreciate any suggestions.

[C. Beaty]

Here’s what Google shows:

http://www.dtic.mil/dtic/tr/fulltext/u2/103817.pdf

There’s a picture on P112 of the PDF file and Ref. 12 on P168 indicates Bensen is the source.

I am vaguely familiar with the scheme; Bensen stayed at my place on several occasions and I would drop him off at Orlando Helicopters where he was pushing this stabilization method.

It gave a helicopter the same control feel and stick free stability as the offset gimbal rotorhead of a Gyrocopter if I don’t have things garbled. Bensen was quite secretive and didn’t disclose much to me.

[Redbaron]

It gave a helicopter the same control feel and stick free stability as the offset gimbal rotorhead of a Gyrocopter if I don’t have things garbled. Bensen was quite secretive and didn’t disclose much to me.[/QUOTE]

Chuck u think a newbie will release the cyclic on a pitch divergent gyro to take advantage of the offset humble head?:)

[C. Beaty]

Perhaps not, Red, but stick pressure from an offset gimbal head nudges the pilot in the correct direction.

An upward gust, for instance, tries to tilt the rotor nosedown and force the stick forward; the correct direction.

OTH, a rank beginner with a death grip on the stick probably doesn’t feel anything except terror.

None the less, a gyro with swashplate is much more difficult to fly than one with a Bensen head, even for an experienced pilot.

I’ve flown both on the same unstable gyro and with swashplate control, total concentration was necessary just to stay rightside up. With Bensen head, I could relax and let the thing fly itself.

The downside of the Bensen head is the false sense of security has no doubt led some to kill themselves in unstable gyros. "It's so stable it flies hands off."

[msmfi]

http://www.dtic.mil/dtic/tr/fulltext/u2/103817.pdf

Chuck,
I can only confirm that exactly that document triggered my question ....
:)

[kolibri282]

Mirek,

thank you for your question since the paper that Cuck posted definitely is an asset for our "Technical Papers, Books, and Publications" subsection. To make it easier to find it I would like to rename this thread to reflect the title of the paper but not before a week or so has elapsed to have a chance of finding the one you were actually looking for (in which case I would give the thread this title and open a new one for Chuck's find). What do you think?


Chuck,

any chance you can dig up the other parts of this report?

[C. Beaty]

I’m sure GE has an archive but it’s likely inaccessible to outsiders, Juergen.

[C. Beaty]

Juergen, here’s a paper on stabilization via chordwise overbalance of rotorblades that you might want to include in your database:

http://www.dtic.mil/dtic/tr/fulltext/u2/017205.pdf

Bensen also published a paper on this subject that I’ve been unable to locate.

[kolibri282]

In the first paper that Chuck had posted (#2) the helicopter equations of motion are listed. in the X-direction equation the term below appears. The first part of it (-s^2/oM^2*h/R) is the second derivative of the pitch attitude angle with respect to time (hence the s^2). Unfortunately the derivation of this equation is not in the text and I have never seen this term before in any of the force equilibrium equations so far. Does anyone have an idea how this term is derived?
Any hint would be highly appreciated.

Thanks,

Juergen

[msmfi]

To make it easier to find it I would like to rename this thread to reflect the title of the paper but not before a week or so has elapsed to have a chance of finding the one you were actually looking for (in which case I would give the thread this title and open a new one for Chuck's find). What do you think?

Juergen,
Sorry for being late with the response .... Eastern school holiday, You know ...

Probably no chance to find Dr. Bensen's publication remotely, e.g. without visiting any of the libraries ...
What we could do is to introduce a new thread explicitely refering to:

AD103817

HELICOPTER HANDLING QUALITIES INVESTIGATION
PHASE II: ANALYSIS OF HELICOPTER STABILIZATION AND CONTROL PROBLEMS
PART C: CHARACTERISTICS AND COMPARISON OF EXISTING HELICOPTER STABILIZING DEVICES
Cornell Aeronautical Laboratory, Inc., REPORT NO. TO-707-8-2