Lu,
In answer to your first post on this thread, starting with your assumptions:
<font face="Verdana, Arial, Helvetica" size="2">1)In order to be able to work on the Robinson Helicopters you attended a factory school or, you attended a Robinson sponsored school that was operated by a Robinson distributor.</font>
1. I am not aware of any
requirement to attend a Robinson factory course just for the purpose of being able to maintain them. I believe that this requirement only gives the company that the AME works for, the right to call itself an approved Robinson Service Centre. (Correct me if I am wrong)
<font face="Verdana, Arial, Helvetica" size="2">2) You were taught flight theory as well as how to rig the helicopter.</font>
2. Yes we are taught flight theory, but as a basic subject. After talking to a couple of maint. Engineers who had attended Robinson maint. courses, they said flight theory was not on the agenda on those courses. The courses were strictly based on the maintenance manual content.
<font face="Verdana, Arial, Helvetica" size="2">3) If you were taught in the USA you were told about gyroscopic precession and if you were taught in the UK or OZ you learned it in a different way. (Unless the subject was taught by a Robinson representative).</font>
3. Cannot confirm or deny if we learnt about gyroscopic precession in a different way to the yanks, but the reference material I can remember came from USA and UK. A couple of books that come to mind, on top of the ones you have mentioned on other threads are
‘Helicopter Design & Data Manual” by S.J.Dzik (USA) and
‘The Helicopter” History, Piloting and How it Flies by John Fay (UK). Prouty was another one
Your Questions:
<font face="Verdana, Arial, Helvetica" size="2">1)In learning about gyroscopic precession or the same phenomenon as taught in the UK or Oz did they use the Robinson system as a demonstration or, did they use a Bell system as a means of explaining the subject?</font>
1. When I learnt about Gyroscopic Precession the Robinson helicopter did not exist.
The
Fay description is very basic (one small paragraph) and in its last sentence, basically states that some rotors can be said to behave like a gyroscope in that their phase-lag is 90 deg.
That is how I have always understood gyroscopic precession!
No helicopter types are used as an example on
that subject but several types (pre-Robinson) appear as examples throughout the book.
The
Dzik description: (again, pre Robinson) has more detailed explanation of the phenomenon but ultimately says that on a spinning disc, the reaction is
approximately 90 degrees in direction of rotation from the input force.
I think that all helicopter engineers/AMEs understand this principal as well as the pilots. You just have to be able to interpret the different terminologies for the same things. There is no reference to the different types of helo’s, as to the effects after the helicopter is in flight.
<font face="Verdana, Arial, Helvetica" size="2">2)In teaching the rigging process how did they explain the differences in the positioning of the Robinson blades as opposed to those of a Bell helicopter and, how did they rectify what they taught about gyroscopic precession as related to the positioning of the blades?</font>
2. I believe the rigging process is taught as per the MM with little or no explanation on the GP principles as the subject is covered in basic pre-licensing exams. I also do not think any other manufacturer would have an agenda to re-teach what is considered a basic subject for maintenance personnel.
One point: After looking at a Robbo rotor head, I can see a delta 3 effect in the R22 head between the ‘teetering hinge’, and the pitch horn and maybe a slight coupling effect between the coning hinge and the pitch horn, depending on the collective setting at any given moment, ie; whether the pitch horn/rod attachment is below, level or above the centreline of the coning hinge.
How it all works in flight? …… I have you, Frank Robinson and all the other contributors to this subject to draw on.
As far as understanding any helicopter for the purpose of maintaining them, I can only go by what the manufacturers officially tell us.
A question I have: Is comparing rotors to discs when explaining gyroscopic precession truly correct? …. Even when the rotors are in the shape of a constantly changing
cone when in flight?
Lu, I have not personally attended any Robbo Maintenance courses but a couple of fellow maint. Engineers have. (Over 10 years ago).
The last R22 that I worked on was over 10 years ago
------------------
sprocket: .. No standards? Nooo problems!
[This message has been edited by sprocket (edited 07 January 2001).]