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Author Topic: P-18  (Read 2796 times)
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ram
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« Reply #25 on: March 05, 2017, 03:43:44 PM »

I'm hoping to get my daughter to build a P-18. In the AMA P-18 rules it states unmodified commercially available "unit" (Max Dia 6").  Does this mean you have to use the plastic hanger that comes with them?   I have a box of old red plastic 5.5" props but not on hangers.  Can she use these with her own bearing or do I need to buy some fresh  "units"? What about 6" Tern Aero props or 6" Kaysun props?  I have several of those, also and they didn't come with hangers.  I don't mind buying some fresh prop "units" if I need too.   Is there a list of legal props?
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dslusarc
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« Reply #26 on: March 05, 2017, 05:22:04 PM »

Ray,

Putting my CD hat on, I read the rules to govern only the "prop" itself not the "prop assembly" or "prop with hanger assembly" etc. So as CD I would allow an unmodified 6" turn Aero prop to be used with a thrust bearing and prop shaft of your choice. The use of the term "unit" does not necessarily require anything more than the molded prop be considered as the "unit" as I looked up the definition of "unit'" and a unit can be "a single thing, person, or group that is a constituent of a whole". So that to me means the "commercial unit" can be just the prop or a prop/hanger assembly. I am assuming that it was worded that way to allow both styles to be legal. If not then it will have to wait until the next rules cycle for a clarification.   

Don
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ram
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« Reply #27 on: March 05, 2017, 08:52:35 PM »

Thanks Don. I had an off list suggestion that the 6" Ikara would be a good choice. I'll let her measure and compare all the props I have and then decide.  I had thought that the Ikara wouldn't be legal due to it being made up of several pieces,  but after reading what you had to say I tend to agree that it is legal.

Rey
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ram
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« Reply #28 on: March 06, 2017, 09:36:01 AM »

Also, in an off list response, it was mentioned that they glue the prop shaft into the prop.  I believe that in outdoor P-30 that would have been considered modifying the prop and not allowed.  It seems that attaching anything to the prop other than balance weight to one blade, which is specifically allowed, would be a modification.  It seems like the next step would be to add a gurney flap or maybe some blade area.  Thoughts?  Am I thinking about this too much?  If so just tell me to shut-up!!!

Rey
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mkirda
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« Reply #29 on: March 06, 2017, 09:54:26 AM »

Modifying the prop shaft is not disallowed, so I can see no reason why it would be DQ'ed. Assuming you are removing the Ikara shaft and replacing it with something else, i.e. longer or thicker.
This is different than say, cutting down the prop area or modifying the pitch distribution.

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Mike Kirda
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dslusarc
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« Reply #30 on: March 06, 2017, 10:46:02 AM »

I went and read the P30 rules since I do not fly outdoor and the rules state the prop must freewheel in that event. So if you glued the shaft to the P30 prop then it will not freewheel so I can see that being illegal for P30. There is no such requirement in the P18 rules.  I would not consider installing a shaft into a prop as modifying the prop. How else is one expected to make the prop spin?
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dslusarc
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« Reply #31 on: March 06, 2017, 10:50:39 AM »

The multiple pieces of the Ikara prop will satisfy a plastic prop rule but not a one piece molded plastic prop rule. P18 had no material requirement other than the prop must be commercially available. So if a person commercially sold wooden props they are legal as well.
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ram
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« Reply #32 on: March 06, 2017, 10:56:41 AM »

The multiple pieces of the Ikara prop will satisfy a plastic prop rule but not a one piece molded plastic prop rule. P18 had no material requirement other than the prop must be commercially available. So if a person commercially sold wooden props they are legal as well.

Like these?:  http://hobbyspecialties.com/product_info.php?products_id=33&osCsid=35cb99dabb318728b166da5ac41f1ce0

I'm not sure I like where this is going.

Rey
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mkirda
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« Reply #33 on: March 06, 2017, 11:26:09 AM »

A short run of balsa props with carbon hub that allows for adjustment of pitch maybe?

Yeah, I see where you are going, Rey. I thought the intent was plastic props, but the lack of restrictions of material make this sort of prop not only likely but inevitable.
In fact, the wheels are already turning...

Regards.
Mike Kirda
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dslusarc
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« Reply #34 on: March 06, 2017, 11:28:23 AM »

As a CD I see nothing in the P18 rules to not allow those props. This is an example of why it should not have been quickly adopted as an AMA event. The rules should have been agreed upon then test flown to find the loopholes/omissions etc especially under AMA interpretation.  Now it is stuck as an AMA event in a 2 year rules cycle.
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jakepF1D
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« Reply #35 on: March 06, 2017, 11:44:32 AM »

Don,

It's not actually an AMA event per se, it's only a provisional event.  The intent was to get it in the rule book specifically so it could be flown at numerous contests, and issues like this could be discovered before it becomes an official event (assuming it actually does).  Also, the requirement for a commercially available prop is specifically to remove the need for a beginner to build a prop which many deem a barrier to entry.  If someone decides to sell a better prop at a reasonable price, then I don't see an issue with that.  The key is that it's widely available so anyone has access to it.  A one time run of 10 props does not qualify as commercially available.  If this becomes a problem, then the issue can be addressed in the next rules cycle.
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ram
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« Reply #36 on: March 06, 2017, 11:47:17 AM »

Isn't there an option of a formal rules interpretation being submitted to the contest board?  I wasn't involved in the formulation of the P-18 event so I don't know if the rule was meant to restrict to plastic props or not.

Rey
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mkirda
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« Reply #37 on: March 06, 2017, 11:47:54 AM »

What is a good adhesive for the plastic material mentioned in the rules?

Not used non-mylar plastics previously.

Regards.
Mike Kirda
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jakepF1D
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« Reply #38 on: March 06, 2017, 11:58:05 AM »

What is a good adhesive for the plastic material mentioned in the rules?

Not used non-mylar plastics previously.

Regards.
Mike Kirda

I used rubber cement which seemed to work reasonable well.
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dslusarc
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« Reply #39 on: March 06, 2017, 12:07:54 PM »

Mike,

I used 3m77 spray adhesive with produce bag covering for my Science Olympiad which is essentially the same event.
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mkirda
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« Reply #40 on: March 06, 2017, 12:10:19 PM »

Great, thanks guys!

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dslusarc
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« Reply #41 on: March 06, 2017, 12:20:07 PM »

Jake,
I mean its a AMA event in the sense it must follow a 2 year cycle. If it was left outside the AMA constraints during this developmental  period it could have these issues adjusted much easier and immediately if needed. I do not think it was intended to allow wooden props but people have to be prepared to see them for the next two years provided they can be commercially bought.

Your comment of a one time run of 10 pieces not being "commercially available" is interesting as there was a similar argument used in regards to Y2K2 film not being commercially available years ago as there was a limited supply due to it being an experimental one time run of film. In F1D it makes no difference due to the rules but Pennyplane, LPP, Int stick, Manhattan, and EZB  have that  in it and records have been set with Y2K2 film covered planes with a film that can be considered by some as not commercially available.

It may be difficult for the indoor board to say on one hand Y2K2 is still commercially available but a short run of props is not. Perhaps the term needs clarification??
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mkirda
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« Reply #42 on: March 06, 2017, 12:25:04 PM »

It may be difficult for the indoor board to say on one hand Y2K2 is still commercially available but a short run of props is not. Perhaps the term needs clarification??

Also commercially available WHEN?
I've heard of older props from the 1970's timeframe that had better P/D ratios than what is currently available.
Are these no longer usable since they are no longer commercially available?
Or since they once were, they are still OK now?

Regards.
Mike Kirda
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ram
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« Reply #43 on: March 06, 2017, 12:28:03 PM »

In the similar vein to Don's comments above, I was having an off list discussion and posited the below:

As far as "old" props I have a red 5.5" that looks like a North Pacific / Sig, but has a pitch of 9.3" at the 2" radius!  All the others have a pitch just over 6".  It came out of a different mold than the others because the front has a recess in it.  I can't imagine that it would still be considered commercially available, but does that mean if all of a sudden Sig quits making props (or Ikara,etc.) those props become instantly illegal?

Rey

(Isn't this fun?!?...NOT!)
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Bredehoft
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« Reply #44 on: March 06, 2017, 12:34:47 PM »

Don and all,

Regarding "commercially available", limited production, etc., consider this - the North Pacific Sleek Streek Prop (and assembly) is a popular "unit".  However, the original, while mass produced in the thousands and thousands, is no longer available commercially.  (There is at least one reproduction, but the prop is not the same as the original NP prop.)

I know that is splitting hairs, but all rules discussions are just that.  This can apply to any item that is deemed to be commercially available, whether propellers, covering, or any other thing and the term is a slippery slope.

Even the P-30 requirement for "unmodified" causes discussion, even this long after the rule was made (ramps cannot be removed, additional clutches cannot be added, etc.).

One restriction that some groups use is "one-piece plastic prop" - that eliminates Ikara indoor props (and most that Mike might be thinking of creating  Wink )  This rule does allow modifications to the one-piece plastic prop, such as trimmed to max diameter or shaving.

People will always try to find loopholes.  That is not always bad, especially in the world of limited production for Free Flight modeling.

(NOTE - Rey and Mike commented similarly while I was typing this!)

--george

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« Reply #45 on: March 06, 2017, 12:38:28 PM »

In a lighter vein,

Here is a video of a P-18 mass launch that occurred at an indoor contest in COlorado Springs yesterday.

It may only be visible if you have a facebook account - not sure....

https://www.facebook.com/groups/626401977506260/1089571764522610/?comment_id=1089579227855197&notif_t=like&notif_id=1488770981380927

--george
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dslusarc
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« Reply #46 on: March 06, 2017, 12:42:06 PM »

It may be difficult for the indoor board to say on one hand Y2K2 is still commercially available but a short run of props is not. Perhaps the term needs clarification??

Also commercially available WHEN?
I've heard of older props from the 1970's timeframe that had better P/D ratios than what is currently available.
Are these no longer usable since they are no longer commercially available?
Or since they once were, they are still OK now?

Regards.
Mike Kirda



Mike,

I have some of those old red props, they are also much lighter about 1.7 grams compared to 3 grams or so for newer red props. They have a lot less plastic on the hub. The old style red prop is what is on my Phantom Flash :-)

Don
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dslusarc
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« Reply #47 on: March 06, 2017, 12:49:32 PM »

This just shows how hard it is to write a set of rules!

Don
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jakepF1D
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« Reply #48 on: March 06, 2017, 02:08:19 PM »

Jake,
I mean its a AMA event in the sense it must follow a 2 year cycle. If it was left outside the AMA constraints during this developmental  period it could have these issues adjusted much easier and immediately if needed. I do not think it was intended to allow wooden props but people have to be prepared to see them for the next two years provided they can be commercially bought.

Your comment of a one time run of 10 pieces not being "commercially available" is interesting as there was a similar argument used in regards to Y2K2 film not being commercially available years ago as there was a limited supply due to it being an experimental one time run of film. In F1D it makes no difference due to the rules but Pennyplane, LPP, Int stick, Manhattan, and EZB  have that  in it and records have been set with Y2K2 film covered planes with a film that can be considered by some as not commercially available.

It may be difficult for the indoor board to say on one hand Y2K2 is still commercially available but a short run of props is not. Perhaps the term needs clarification??

I do think it would be beneficial to define commercially available.  To me there are two factors in play here.  One is defining when something is considered commercially available, and second is determining whether something that is no longer available still qualifies. 

On the first point, I could envision a couple ways to define commercially available, but I wouldn't want to go too far into the weeds.  This is something that would require a a fair bit of discussion to nail down.

On the second point, I think once something is deemed legal under the definition of commercially available, it should always be legal.  That is to say a model built 15 years ago when Y2K2 was still available shouldn't ever be made illegal.  Similarly anyone that happens to have a stash of Y2K2 should be able to use it.  If we begin banning things that are no longer available, then everyone would need to buy a new batch of rubber every few months.

These are of course just my opinions, and perhaps this should be discussed further among the indoor board members.
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Olbill
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« Reply #49 on: March 06, 2017, 03:11:07 PM »

IMHO the right way to solve this problem is to have one rule for props - 6" max diameter. Let the people who are competing decide what works best and how to get it.

I'm not familiar with this year's SO rules but recently there's been no restriction on the prop other than diameter. If it's good enough for SO then it should be good enough for AMA.
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