P-18 Proposal - an analysis of the rules

From: <joshuawfinn_at_gmail.com>
Date: 20 Jun 2016 05:17:16 -0700

Gentlemen,
 

  Since the P-18 thing keeps being an ever present topic, I think it's time to address actual issues with the rule as proposed. The design of the event has some actual problems--major loopholes which need to at least be expressed for discussion regardless of whether a cross proposal fixes them. The 2 minute max simply is not going to happen, so these models will, as intended, be flown to the limits of their performance. Some of that performance can be limited by dealing with the loopholes allowing state of the art aircraft to fly this event.
 

 1. Covering material: I have concerns about the ability to verify that "HDPE shopping material" is being used. Also, what exactly is tissue? The definitions need to be in line with already existing events. Would using OS film impact the model's performance? Sure, and probably negatively. On the other hand, adding in a few gadgets might make the use of lightweight covering a beneficial thing. How easy is it for a beginner to cut up and adhere a veggie bag? I know I haven't really enjoyed using the stuff the few times I've tried it. Mylar for outdoor modes is considerably easier. Anyway, not a major loophole, but issues in need of consideration.
 

 2. No mention of gadgets. Are we ok with allowing torque burners? I can't see anything in there preventing them from being used.
 

 3. Length of model--this is a beginner's event, right? What about the beginner who shows up with his model built faithfully to published plans but accidently put in too much tail boom offset? Now his stab tip is sticking outside the 18" limit and he's no longer legal. This one might be ok, but we need to be aware of the issue.
 

 4. The commercially available propeller thing already features data in the form of P-30. Let's be realistic, I run a small business selling, among other things, indoor prop parts. I have no qualms introducing a cut down Peck 7" with one blade shaved for balancing. Before you say that's illegal, remember that it's a "commercially available unit", and the unmodified bit has already been accepted to only pertain to modifications from the state in which it is commercially available. I can trim it and re-pitch it to my heart's content, it's merely the end user who can't. Also, the rules here do not allow the removal of mold flashing or reaming out the hole for better alignment and fitting a bushing. These mods are allowed in P-30 and for good reason.
 

 5. "hook to hook distance"? Uhm...no other event defines it this way. Should this not be front bearing face to rear hook distance? Otherwise the models won't be legal for LPP as has been so much vaunted as one of the virtues of the event. I guess it's handy if we want canards to be competitive. Let the extension shafts begin!
 

 6. No materials limitations whatsoever. Rolled tubes, carbon booms, boron/balsa spars, etc are all fair game. Even bracing if someone thinks they need massive amounts of rubber. Is this within the intent of the event? One could make the case that models with carbon fuselages are easier for beginners, but they're also not eligible for LPP, which I remind us all has been so vaunted as one of the event's virtues. If we are going to leave this wide open, why are we requiring commercially available props?
 

 7. Back to the prop thing: Uhm yeah, "unmodified commercially available unit with a maximum diameter of 5.5 inches." Gentlemen, upon passage of this event, should this wording be retained, J&H Aerospace will be releasing a special carbon/balsa molded prop with flaring spars for a low introductory price of $20 each. We will also produce a VP version with symmetrical blades for $60 each. Hey, it's within the definition of the rules!
 

 Now, if this event is going to be ratified, can we at least fix some of these issues? It's seriously ridiculous otherwise. I like playing with VP's, and I find that beginners are fascinated by them, but they have no place in an event with a 5.5" prop diameter, regardless of whether it's a "beginner's event". Even I can see the ridiculousness of a P-18 doing 6-7 minutes.
 

 -jf
 

 

Received on Mon Jun 20 2016 - 05:17:17 CEST

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