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Author Topic: P-18  (Read 9562 times)
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ram
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« Reply #50 on: March 06, 2017, 03:24:50 PM »

I agree with Bill except I do think that it should be limited to plastic props since this is an introductory event.  Most, if not all, the SO/TSA kids are using Ikara props.  They are familiar and comfortable with them.  I believe the current SO plane meets the P-18 rules and I would be in favor of keeping them legal so that they could fly in an AMA contest.

Rey
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mkirda
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« Reply #51 on: March 06, 2017, 03:33:05 PM »

Hi Rey.

Kids are modifying Ikara props though and flying them in SO competition.

At Racine last week, the best flying plane flew a full minute longer than the rest using standard SIG props.
It was some variation on Ikara. I am not sure what exactly as I did not examine it.

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Mike Kirda
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ram
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« Reply #52 on: March 06, 2017, 03:41:33 PM »

Mike,

I think that is perfectly fine.  A plastic prop of max 6" diameter.  Encourages experimenting. 

I know my daughter would be bored if it was so restrictive that everyone had the exact same plane.  She just competed in a balsa bridge competition put on by the ASCE chapter here and loved it because the parameters allowed a lot of variation.  She designed and built her own bridge (with NO help from me) and, even though she didn't win, had a blast and is already planning her next "more improved" one.

Rey
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Olbill
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« Reply #53 on: March 06, 2017, 03:49:16 PM »

But wood props are legal in SO. Most of the SO fliers I've heard about are using plastic props either for simplicity or b/c they think they work better. I'd like to see the same choice allowed in P-18.

Also, if this event is supposed to make people want to fly more advanced indoor F/F I'd like to see some level of thinking involved. Once you leave P-18 the "little gray cells" that Poirot talked about are going to have a big work load.

So I can see this scenario for P-18 at a series of AMA contests:

Ist contest
Flier #1 uses a solid plastic prop.
Flier #2 uses a modified Ikara prop and wins by 5 seconds.

2nd contest
Flier #1 uses a modified Ikara prop
Flier #2 also uses a modified Ikara prop
Flier #3 uses a home made balsa prop and wins by 5 seconds.

3rd contest
All fliers use home made balsa props
All fly well but the winner located some good rubber since the last contest.
Then:
Fliers 1-4 notice how much nicer the LPP's fly than their P-18's
Fliers 1-4 know how to build balsa props and decide that building an LPP can't be all that difficult.
And if we are lucky one of those fliers will get hooked on iindoor F/F
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Olbill
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« Reply #54 on: March 06, 2017, 03:53:41 PM »

As we speak Don Deloach has put forth an interpretive rule change to limit props to one piece unmodified plastic props with only weight added for balancing to be allowed.
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dslusarc
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« Reply #55 on: March 06, 2017, 04:01:37 PM »

The current SO models do not necessarily meet P18 rules. They are close but not the same. Most SO models are not legal for P18 due to motor sticks being longer than 10", overall length greater than 18", and cut down and or repitched Ikara props.  Trying to make P18 parallel with SO will not works as SO changes every year. Next year could be 8" prop or 3" chord etc. Best to give  P18 it's own identity I think.
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aardvark_bill
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« Reply #56 on: March 06, 2017, 05:56:28 PM »

As we speak Don Deloach has put forth an interpretive rule change to limit props to one piece unmodified plastic props with only weight added for balancing to be allowed.

So the 150 mm Ikara won't be legal under this interpretive rule, correct, because it is not one piece?
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mkirda
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« Reply #57 on: March 06, 2017, 06:03:23 PM »

If it is sold as one piece, isn't it one piece?
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Olbill
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« Reply #58 on: March 06, 2017, 07:05:42 PM »

Sounds like the interpretive rule might need some more interpretation.
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ram
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« Reply #59 on: March 06, 2017, 07:43:17 PM »

I think it's clear enough except for the "commercially available" part that is undefined. The Ikara is plastic, within 6", available, and comes in one piece as opposed to separate parts (blades and spar).
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dslusarc
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« Reply #60 on: March 06, 2017, 08:06:07 PM »

As an example on another event, for FAC Phantom Flash they worded it as "one piece molded plastic" so my old Ikara prop was illegal as it was not molded. So P18 perhaps should be re-worded as:

"The propeller shall be an unmodified commercially available one piece molded plastic prop with a maximum diameter of 6 inches. Weight may be added to the blade for balancing."

Don
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ram
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« Reply #61 on: March 06, 2017, 08:43:25 PM »

As an example on another event, for FAC Phantom Flash they worded it as "one piece molded plastic" so my old Ikara prop was illegal as it was not molded. So P18 perhaps should be re-worded as:

"The propeller shall be an unmodified commercially available one piece molded plastic prop with a maximum diameter of 6 inches. Weight may be added to the blade for balancing."

Don

But that gives us who happen to have a special  molded plastic prop with higher than normal pitch an advantage while the Ikara levels the field.
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dslusarc
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« Reply #62 on: March 06, 2017, 09:27:26 PM »

The Ikara's vary in pitch as well, sometimes one blade to another! I will say in regards to the Ikara prop on SO models, those 6" ones spin around 1000 rpm and the 7.5 gram models can and do easily damage them when landing or hitting. The blades get bent back where the prop spar ends. The kits they started with had small wood spar extension they glued on. If a blade gets broken then my guess is repairing would not be allowed as it is has then been modified??? Just a thought.  

In my discussion with Don DeLoach in regards to his Interpretation Proposal he has put forth to the Indoor Board, he told me the original intent was to use the 5.5" one piece molded props with the hangers (like on an AMA Delta Dart) then during the cross proposals the hanger part was dropped etc and left with a 6" plastic prop that the builder can install their own shaft and use their own prop hanger. I was not on the Indoor board at that time and there are no records of board communications I can see for current board members to look at (an archive so to speak) to see what all was discussed.

I was just reading the board procedures when I got home after work and an interpretation proposal by definition "does not change the existing rule but provides information designed to clarify it. It deals with interpretations of the rules, or ways in which the rules are applied in the field, where situations are not clearly dangerous."

Consequently I do not think adding the terms "single piece plastic" is an interpretation of the current rule, it seems to me like a changing of the existing rule from just a prop made from any material to a plastic prop. To me an interpretation would be if the rules said "plastic prop" and the interpretation was that "plastic prop" means the prop can be made from plastic material (like and Ikara) or molded from plastic (like SIG red prop).

I believe this to be especially in light of the fact that an urgent proposal is defined as follows:
"Urgent proposals are not an interpretation of existing rules or necessarily related to safety. Urgent proposals are proposals that cannot wait for the normal rules change cycle due to there being a problem with the current rules that adversely affects the event in some manner. An Urgent proposal will constitute an actual change in the rules, and therefore the justification for this type of proposal must be very closely scrutinized to prevent abuse."

I think changing from any commercial 6" prop to a commercial single piece plastic prop is a rule change not an interpretation. So my question is then did the board intentionally leave the wording of plastic out on purpose? Or was it an oversight during the cross proposal process? This will affect how I vote on any urgent proposal. If the printed rule book is not the voted on and agree rules by the board then it needs to be fixed with an urgent rule change. If the rules are as voted on then I think they should be left alone for now until the next cycle where people can submit changes like normal.  

Don




 
  
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Olbill
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« Reply #63 on: March 06, 2017, 11:02:26 PM »

I'm leaning towards voting against the "clarification".
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ram
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« Reply #64 on: March 07, 2017, 05:54:21 PM »

For any that may be wondering what happened with the P-18 propeller rule being discussed above, it was discovered that the full text of the approved rules proposal for the P-18 propeller was inadvertently left out of the final print version.  It has since been corrected in the rule book and noted as such at the front of the book on page i.  The entire AMA Indoor rule book is here: 

https://www.modelaircraft.org/files/IndoorFreeFlight2017-2018.pdf

The relevant language is now: 

25.4.
The propeller shall be an unmodified commercially available plastic prop with a nominally maximum diameter of 6". If the propeller is advertised as being a 6" unit, it is acceptable for this event. Weight may be added for balancing.

Rey
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leop
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« Reply #65 on: March 07, 2017, 07:50:37 PM »

The addition of the words "one piece molded" is the proposed "clarification."  Or not a "clarification" but an additional restriction that should await and follow the two year rule change cycle.

The proponent of the "clarification" should probably have proposed "molded in one piece" if I understand the intent of the additional restriction.

The current rules clearly allow the 150cm Ikara prop.  Please note that many plastics, including many used for injection molding are not pure resins but have fillers, including fibers, for additional strength, toughness, and bulk, etc. (as well as to reduce cost).  Also, please remember that epoxy and polyester are plastics.

By the way, a prop with tubes for adjustable pitch would probably fall afoul of the unmodified restriction as any pitch change would be a modification of the prop. 

Finally, "commercial available" is the term of art used in the AMA Builder of Model rule.

LP
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dslusarc
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« Reply #66 on: March 07, 2017, 08:43:35 PM »

Leo,

Once the missing text was found to be a clerical issue the Interpretaiton Proposal that was submitted was withdrawn by the submitter. So the Ikara props are legal. Redefining "plastic prop" to a "one piece molded plastic prop" or similar would have to be introduced next rules cycle.    

Don

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Olbill
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« Reply #67 on: March 08, 2017, 08:24:44 AM »

I'm a little confused as to how a CD would detect a prop pitch change. Or why a pitch change would be illegal in the first place.
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leop
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« Reply #68 on: March 08, 2017, 12:37:49 PM »

The commercially available prop must be "unmodified."  Changing the pitch is a modification from the shape or form present when purchased.  With tubes, such a pitch change is easy (but one still may add glue to keep the pitch stable - also not allowed) .  However, even one piece injection molded plastic props can have their pitch distributions modified using a bit of gentle manipulation and, perhaps, a heat gun.  This can easily be done without leaving the tell tail lightening of the strained plastic.

The detection of such modifications is different thing.  It might be hard for a CD to detect such a change but it is a change or modification nevertheless.  The competitor knows that the modification has been done. 

Or, if a rule violation is undetected by the CD, does this mean there is no rule violation?

LP
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ram
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« Reply #69 on: March 08, 2017, 01:01:22 PM »

Has anyone had one of these in their hands:

http://www.pitsco.com/Propeller_Assembly

They come in packs of 35 for $15.  I would be interested in what pitch the blades have at 2" radius or thereabouts and how much they weigh.  If no one has seen them I'll go ahead and order and measure myself.  If they are useable I'll bring to West Baden and Rantoul and pass them out to whoever wants to try them.  After shipping they are only .60 each.

I did contact the company who replied that they have no data to share with me.

Rey
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Olbill
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« Reply #70 on: March 08, 2017, 02:28:13 PM »

The commercially available prop must be "unmodified."  Changing the pitch is a modification from the shape or form present when purchased.  With tubes, such a pitch change is easy (but one still may add glue to keep the pitch stable - also not allowed) .  However, even one piece injection molded plastic props can have their pitch distributions modified using a bit of gentle manipulation and, perhaps, a heat gun.  This can easily be done without leaving the tell tail lightening of the strained plastic.

The detection of such modifications is different thing.  It might be hard for a CD to detect such a change but it is a change or modification nevertheless.  The competitor knows that the modification has been done. 

Or, if a rule violation is undetected by the CD, does this mean there is no rule violation?

LP


I wasn't advocating for cheating. I just think it's a silly restriction and difficult to enforce.
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leop
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« Reply #71 on: March 08, 2017, 05:16:00 PM »

Bill,

I agree that having a rule that is difficult to enforce could be a problem and, in some cases, is silly.  I think that the enforcement of a rule, including the methods of ensuring compliance, should be a prime consideration in the deliberations and vote of the Indoor Contest Board.  Indoor duration flying depends on the honor system to provide for orderly and smooth competitions.   However, the honor system should be backed up by at least the possibility of enforcement.  Rules such as the P18 unmodified prop restriction do not lend themselves to such a backup.

As I think someone said earlier in this thread, making rules is not all that easy.

LP
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mkirda
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« Reply #72 on: March 08, 2017, 05:20:34 PM »

It is also not unheard of to have a manufacturer tweak another's product.
An example from Outdoor:

GizmoGeezer sells a nice prop unit for the P-30 event where the prop is advertised as a re-pitch Peck Polymers 9.5" prop.

Wouldn't be that difficult to do the same in Indoor. Is that now cheating if I sell repitched props?

Regards.
Mike Kirda
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leop
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« Reply #73 on: March 08, 2017, 05:49:38 PM »

The seller of the modified, re-pitched prop would not be cheating.  How this applies to the "knowing" purchaser and user is another thing.  But, my initial comment on this matter was purposely a "draw in" along a path that led to Bill's "silly" comment.  The rules makers need to consider such things. 

In the "remanufactured" example given, one could take this further and have even more remanufacturing, such a lightening and reshaping, done to the prop than just gentle repitching.  So, it is okay if someone purchases and uses such remanufactured props but not okay for the competitor to do the same thing for him or herself.  I guess the out for any competitor is so offer his or her own "remanufactured" props for sale, say at $1,000 each if the sale is not really desired.   This latter point is the true "silliness" of having such an unmodified commercially available rule.  I suspect that everything is "commercially available" at some price.

BTW, there is another thread in the general section of this indoor forum concerning the BOM (builder of model) rule.  That discussion is going along a path not all that dissimilar to this one.

LP
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aardvark_bill
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« Reply #74 on: March 08, 2017, 06:38:01 PM »

Has anyone had one of these in their hands:

http://www.pitsco.com/Propeller_Assembly

They come in packs of 35 for $15.  I would be interested in what pitch the blades have at 2" radius or thereabouts and how much they weigh.  If no one has seen them I'll go ahead and order and measure myself.  If they are useable I'll bring to West Baden and Rantoul and pass them out to whoever wants to try them.  After shipping they are only .60 each.

I did contact the company who replied that they have no data to share with me.

Rey
Rey,
I have a bunch of these at school and will measure the pitch and weight tomorrow.  I'll weigh one with and without the factory hanger.  If you want to try one, I'll mail it to you.
Billy
Billy
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