|
RE: Counterbalanced rudder = improved knife edge?
I'm sure the safest answer is "it depends" :) Imagine a knife edge loop. The rudder is deflected pretty much throughout its full travel during the maneuver. If the straight portion were to go beyond stall AoA, you should feel decreasing rudder effectiveness with more rudder deflection from that point on. Fortunately, I haven't come across a plane like that yet. On the other hand, I do have a plane with flat horizontal stab, where applying more elevator than certain amount is actually detrimental to a tightness of a waterfall..... P.
Posted on: 2/15/2007 12:28 AM by Author "paf"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=5421147
RE: Counterbalanced rudder = improved knife edge?
All the airfoil software I played with has the capability to include a flap at some percentage of the chord. I guess by convention, it still displays AoA relative to the non movable portion - it sure makes the calculations easier that way. What I was trying to say is that it's unlikely that the counter balanced portion is flying stalled. With deflection, its AoA becomes the rudder deflection angle MINUS sideslip angle. But it sure seems that having an aerodynamic counter balance should lessen the effectiveness of the rudder. I also think that the turbulence and lift distribution at the split will make everything so complex, that you either have to do a full CFD analysis and/or wind tunnel tests to get any meaningful data :) P.
Posted on: 2/14/2007 3:39 PM by Author "paf"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=5418786
RE: Extra 300 is born !
[quote]ORIGINAL: as722 I can have it ready for the weekend but I'm looking at 4" of snow right now and we're suppose to get 12" to 16". Hummm...., maybe some skis ? BTW my wife doesn't think I'm fast enough, at building that is. Albert [/quote] Just flip the wheelpants .... P.
Posted on: 2/14/2007 12:42 AM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5416425
RE: Extra 300 is born !
You build WAY too fast ! Has any other Carden 300 flown yet ? If not, I think you should get out regardless of the cold and become the first.... P.
Posted on: 2/13/2007 4:19 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5414059
RE: Counterbalanced rudder = improved knife edge?
[quote]ORIGINAL: da Rock About the differences between an aerobalanced rudder and a plain rudder.......... The aerobalance part of a rudder stalls at a measurably smaller deflection than the plain rudder would. Actually, if you look at the typical aerobalance rudder, it's virtually two different airfoils. The bottom part becomes a cambered airfoil when the rudder deflects. The entire top part of the rudder is a solid symmetrical airfoil. Thin, almost flat actually, symmetrical airfoils stall at lot less angles of attack than cambered airfoils stall at. Do we usually lessen our rudder thows when using aerobalanced rudders? Not anybody I know does. Would you guess that our aerobalanced rudders are probably stalling their top parts in most of the maneuvers that take appreciable rudder? Is that really what we want? At least on our sport planes that aren't 3D? [/quote] I totally agree that the counter balanced portion of the rudder acts different than the rest of it. However, in knife edge, the counter balanced portion is more aligned with the airflow (beta) than the hinged portion. And the hinged portion is seeing a negative AoA during a knife edge flight. I don't think either portion is stalled during a sustained medium/high speed knife edge flight. P.
Posted on: 2/13/2007 1:29 AM by Author "paf"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=5411519
RE: Extra 300 is born !
C'mon Albert - the clear coat has to be dry by now. SHOW IT !
Posted on: 2/5/2007 11:42 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5377497
RE: Props airfoil
[quote]ORIGINAL: dick Hanson If you asked me describe a musical number I could: A - send you a wav. file of it - B- send you the sheet music C- provide the frequencies used for each tone and chord along with a rythmic explanation. (wouldn't that be nice mess ?) Which of these most easily does the job? [/quote] For most people A is the best. For a composer, B might be the better option. For a MPEG data stream compression programmer, C would be very useful. :) P.
Posted on: 2/5/2007 8:13 PM by Author "paf"
in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=5376242
RE: Need help with Mold design
I didn't see the taper in the photos... Anyway, I'd go with a two piece. You should be able to spread the rear portion of the mold somewhat and tilt the plug upward. That should pop out the front recess. Removing parts should be much easier, since they will be much more flexible than the plug. P.
Posted on: 1/15/2007 5:58 PM by Author "paf"
in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=5270306
RE: Extra 300 is born !
That wing tube socket looks like a machine gun barrel shield :) I think the material Denis is using for the plug is called Renboard. I'm really interested in how the canopies get pulled. Carden makes some crystal clear canopies ! Any chance you could get some details on that ? P.
Posted on: 1/14/2007 10:30 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5266615
RE: Need help with Mold design
I recently finished a plug with similar depth recessed lip up front. It wasn't an issue during demolding.
Posted on: 1/13/2007 2:11 AM by Author "paf"
in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=5257209
RE: Need help with Mold design
Why not just 2 part mold with the parting line right down the thrust line ?
Posted on: 1/12/2007 1:27 AM by Author "paf"
in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=5252059
RE: 40% 260 on a Diet
Keyboard pilots, coach builders, Holiday-Inn engineers, back seat designers, one very determined builder - priceless. This is going to be fun.
Posted on: 12/31/2006 7:22 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5189376
RE: Extra 300 Prototype #2
[quote]ORIGINAL: as722 A broken L bracket on its own can and will cause a crash. The minute the L bracket brakes flutter takes over and the rest is history. Albert [quote]ORIGINAL: paf So what evidence were you able to gather to support/disprove different reasons for the failure ? It would be nice to figure it out with some certainty. A broken L bracket on it's own does not a crash make
Posted on: 12/26/2006 12:14 AM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5161769
RE: Extra 300 Prototype #2
So what evidence were you able to gather to support/disprove different reasons for the failure ? It would be nice to figure it out with some certainty. A broken L bracket on it's own does not a crash make.....
Posted on: 12/25/2006 9:51 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5161173
RE: Extra 300 Prototype #2
[quote]ORIGINAL: wgeffon I am not trying to dispute any theory put on here but, one of the planes I witnessed had a dowell in the stab tube and also had an anti-rotation pin in the stab root. Once the L bracket broke the LE of the stab rotated up 90 degrees ripping out the anti rotation pin and the bolt in the stab tube. This is what we came up with on my Carden's to do away with the L brackett alltogether. [/quote] I presume there was a screw in the stab tube as well, so it couldn't simply slide out. If so, it sounds like flutter brought that one down. There's no way any regular force would break off a properly installed anti-rotation pin. However, it is quite possible for flutter to tear apart pretty much anything - L brackets, dowels, plywood plates etc. On my C-arf SX, the stab tube ripped a nice 4" hole in the fuselage side before the stabs departed due to flutter..... In my opinion, any mod that could/would have saved at least one airplane is a worthwhile investment.
Posted on: 12/25/2006 8:59 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5160967
RE: Extra 300 Prototype #2
I had one bracket start cracking on my Cap years ago. It was due to slight mis-alignment of the surfaces. The bolts were slightly stretching the plastic. It also seems that the stab tube always has a little play in it and the stabs can move up/down slightly. This movement gets transfered to the L bracket as well, so over time, it could weaken it enough to fail. Wayne - the first hand failures you know about - did the owners inspect the brackets regularly, or did they leave their stabs on all the time and maybe overlooked a developing crack ? P.
Posted on: 12/25/2006 2:02 PM by Author "paf"
in the forum "Carden Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=5159728
RE: Fiberglass fuselages
[quote]ORIGINAL: Spychalla Aircraft [quote]ORIGINAL: paf Leo - I'm loking at your canopy plug and I'm wondering what the construction process was. Is it a plaster plug made from negative mold, or is it something else ? Thanks, P. [/quote] It is a epoxy gelcoat backed by epoxy glass layed-up inside an existing canopy to create a duplicate. Epoxy is chosen versus polyester because
Posted on: 11/22/2006 12:35 PM by Author "paf"
in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=5026983
RE: Fiberglass fuselages
Leo - I'm loking at your canopy plug and I'm wondering what the construction process was. Is it a plaster plug made from negative mold, or is it something else ? Thanks, P.
Posted on: 11/15/2006 5:21 PM by Author "paf"
in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=5000502
RE: Rollin' my own 50CC Yak 54
[quote]ORIGINAL: SydDythers I heard back from my cutter and he indicated that there were no problems with the cut. Great news mod, your method is valid. No double cutting and the break tabs were great. So paf, I don't know what to tell you? I think maybe opening the file in ACad might have something to do with it? Cheers, John [/quote] That's interesting. What software does you cutter
Posted on: 10/30/2006 11:29 PM by Author "paf"
in the forum "Scratch Building, Aircraft Design, 3D/CAD"
http://www.rcuniverse.com/forum/fb.asp?m=4936193
RE: Rollin' my own 50CC Yak 54
I did the break tabs afterwards in the .dwg format. The problem with that is that if you make the slightest change to your design, you have to redo all the break tabs again manually. I like the method with cutting the part and hiding the "extra" line in the drawing. It should stay all there even if you make changes to your parts. I'll probably make an assembly cut in the layout assembly, instead of doing it part by part though. P.
Posted on: 10/28/2006 1:17 PM by Author "paf"
in the forum "Scratch Building, Aircraft Design, 3D/CAD"
http://www.rcuniverse.com/forum/fb.asp?m=4925400
RE: Rollin' my own 50CC Yak 54
[quote]ORIGINAL: Mods-R-Me [quote]ORIGINAL: SydDythers Mods, I just spent two minutes on our problem and came out with a bit of a solution.... When we export the individual parts into their own files, just draw a rectangle and do a cut extrude of the material all the way through the part before creating the drawing. This will create two tabs each time. Then, in the drawing, make sure you hide the two new edges that were created...hopefully the laser figures out that the hidden lines aren't to be used. Thats the best I've come up with so far. Cheers, John [/quote] To quote yoda "There is another". Just spent 10 min on our problem and found a fix all solution. 1. open part and subsequent drawing (figures 1 & 2) 2. Go to Options -> Line Style -> New and enter new values for line and space length. (figure 3) 3. Name the new line type as Break Tabs. Click save (figure 4) 4. in drawing right click part -> select component line font -> select Break Tabs (figures 5 & 6) 5. Jump up and down because you just acquired a new Solidworks skill [sm=shades_smile.gif]. Mods [/quote] Guys, I went through this issue couple months ago. I too thought I have it all figured out when I created a "Break line" pattern. Unfortunately, it won't transfer into .dwg properly - it's just an attribute for the line, it won't create the desired result :( I ended up inserting the tabs in the exported .dwg using DWGEditor. Also, you can't just create a drawing from a part and have it cut. It will cut every line twice :( Here's what I ended up doing with my project: I designed most of the plane as a multi-body parts, so first, I used the "Save Bodies" function to create individual parts. Then, create an assembly and insert all the parts that will be on a cut sheet. Draw a sketch that has the balsa planks dimensions. Mate all the parts to your sketch plane and position the parts as you wish. Create drawing from an assembly. Insert a view looking at the "thickness" of the parts. Create a "Section View" with empty fill pattern. Position it as near the thicker side of the parts if they are tapered. Save as .dwg This way, you don't have to worry about the double lines that result in laser going twice over and/or near the same spot.
Posted on: 10/28/2006 12:34 PM by Author "paf"
in the forum "Scratch Building, Aircraft Design, 3D/CAD"
http://www.rcuniverse.com/forum/fb.asp?m=4925277
RE: ama rule
[quote]ORIGINAL: KidEpoxy [quote]I do reject the idea that any plane crashing as a result of firing paintballs at it that the crash is/was "accidental".[/quote] ok, lets get the categories filled in, cause Corona making the plane out of PVC & Coroplast as armored against paintballs seems very much linke they took measures to prevent crashes... they use the planes for more than one shoot Which of the following activities that do cause crashes are Accidental a. Marking a coroplast plane with a paintball b. AMA Combat c. AMA Pylon Racing d. Learning to tailtouch e. just flying RC around Some would go with all but E are not acccidental, IF you are going to include opting to do anything other than trafic pattern that may cause an unintended crash. But I dont include that. The Zero shoot was an intended destruction (stomp it on the ground?) while the Corona shoot intended to just paint the planes, hence the PVC & Coroplast armor upgrade. Who can argue that armoring the planes is an INTENT for them to crash rather than evedence to the opposite. Again, INTENT. Non-Accidental. Expected. Reckless, UnSafe, UnAcceptable risk... Anyone have an Expectation Dipstick we can use to see when something IS expected, and when it is UnExpected? Who has seen a Recklessness Meter on the Tower website, I need to buy oine of them.... what is the AMA limit, 4200 on the Reckless Gague? Or is AMA following the euroscale and using the metric Recklessness Guage with 17.2 limit .... where did you guys get your Reckless Gague and what pdf has the cutoff number? Oh thats right. there is no such thing as a Reckless guage, because there is not quantitative measurement for it, only subjective whims. Like UnSafe- nothing IS Totally safe, everything is unsafe to a degree, and there is not SafeMeter to hold up at the paintball shoot and read the displayed amount of safety. Subjective whims. I have asked what odds % folks would use to see when they rate something as Expected, 1 in 10? 1 in 100? 1in 2000? Who wants to mortgage their home to put $100k on #17 in roulette if 1in38 is [i]expected[/i], "I was Expecting #17 cause it its a 1 in 38 chance". See how the word Expected is a really poor choice to aply to the rate that airplanes crash into someone. [/quote] You want a recklessness / safety meter ? Let people bet on stuff. The futures markets and insurance industry are working great on the same principle. I'm willing to bet at 4:1 odds that I'll see a crash during a regular weekend flying at my home flying field. I'm willing to bet 200:1 someone will get hurt during a regular weekend flying (most likely a prop cut to finger/hand). At what odds are you willing to bet something will go wrong during your favorite "safe/unsafe/dangerous etc." R/C activity ? P.
Posted on: 10/27/2006 1:12 PM by Author "paf"
in the forum "AMA Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=4921421
RE: Scoring at the NATS
[quote]ORIGINAL: Anna Wood Paf, The AMA has specific guidelines in the AMA rules General Section for filing protests. See the AMA Competition Regulations on the AMA website. View the pdf file called General Section, page 9, 10 and 12 are relevant to this discussion. http://www.modelaircraft.org/compreg.asp Besides the IMAC Rule Book, this is the other section of the AMA rules that all competitors
Posted on: 7/24/2006 1:14 AM by Author "paf"
in the forum "IMAC"
http://www.rcuniverse.com/forum/fb.asp?m=4537251
RE: Scoring at the NATS
[quote]ORIGINAL: NJRCFLYER2 Heck, if you thought that the raw scores weren't applied correctly, all you had to do was file a protest at the time. Too late now. [/quote] I don't think you get it Ed. We were never allowed to see the RAW scores nor were we told if we received zeros by the judges. Even after the contest was over, the score cards weren't made available to the competitors. P.
Posted on: 7/24/2006 12:42 AM by Author "paf"
in the forum "IMAC"
http://www.rcuniverse.com/forum/fb.asp?m=4537168
RE: Scoring at the NATS
[quote]ORIGINAL: Phaedrus-MMVI [quote]ORIGINAL: paf The proposed judge was OPTIONAL, meaning the CD has the option to utilize it. Some of the Unknowns are almost impossible to follow and I'm sure the competitors from the same class who studied the unknown could collectively work as a maneuver judge. How many times have you seen 4 or 5 pilots say - "he just zeroed that !!!!!"
Posted on: 7/22/2006 2:34 PM by Author "paf"
in the forum "IMAC"
http://www.rcuniverse.com/forum/fb.asp?m=4531831
RE: Scoring at the NATS
[quote]ORIGINAL: Phaedrus-MMVI [quote]ORIGINAL: paf b) several missed hard zeros - I still don't uderstand why the ingenious IMAC rules proposal for maneuver judge got tabled :([/quote] Your first point is the reason. It is difficult enough on a CD to seat sufficient judges just for the normal contest, adding the requirement for yet another set of judges is simply not reasonable. [/quote
Posted on: 7/22/2006 12:56 PM by Author "paf"
in the forum "IMAC"
http://www.rcuniverse.com/forum/fb.asp?m=4531569
RE: Scoring at the NATS
[quote]ORIGINAL: Anna Wood paf, For the Pattern Nats, do the contestants also judge/scribe? Regards, Anna Wood Queen Creek, AZ [/quote] I'm pretty sure they do contestant judging. Every judge is certified, Masters pilots judge FAI, FAI pilots judge Masters.... They don't have to study unknows though :) They also run qualification groups with TBL adjusted matrix to determine finalists
Posted on: 7/22/2006 1:14 AM by Author "paf"
in the forum "IMAC"
http://www.rcuniverse.com/forum/fb.asp?m=4530422
RE: Scoring at the NATS
[quote]ORIGINAL: cmitch232 My understanding is that the controversy has more to do with what type of radio you are flying, i.e. Futaba vs JR, and possibly your reputation. Some are saying that the Futaba guys are being scored higher. This is not the first time I've heard this, and I've heard it from more than one source. [/quote] These rummors always float around ... and in my opinion are completely baseless. The issues I've seen in Unlimited class: a) not enough judges - there were numerous cancelations by judges prior to the event. This resulted in 95% of Unlimited flights judged by only 3 or 4 people over and over. Most of these judges, from my understanding, were from the same area (North Central Region). Every judge brings his own version of "what is it supposed to look like" into the judging chair with him. If all of them are used to the style of flying that's prevailing in the area, the local pilots will have a slight advantage. A simple thing as a wing level flight can cost you 0.5 - 1 point, just because the judges consider "level" different than you - if you're the unlucky one and get cought up in it every flight of every round - it will cost you in the end. b) several missed hard zeros - I still don't uderstand why the ingenious IMAC rules proposal for maneuver judge got tabled :( c) unability of pilots to see their individual scores after every round/day of flying - this was a real killer, especially with the same judges judging you over and over and pilots being forbidden to communicate with judges after flight. d) The software bug that mixed up the K-factors - no biggie there. e) No access to score sheets after the contest was over - including up until now. That will feed the conspiracy theories for sure. Considering that at least half of the unlimited pilots were displaying flights with MINIMAL mistakes, the final standings become a partial lottery :( If pattern can put together FIVE judges for FAI, I think IMAC could as well. In retrospect, I woudn't mind judging couple rounds during the NATS, if in turn I was exposed to more diverse judging pool... P.
Posted on: 7/22/2006 12:25 AM by Author "paf"
in the forum "IMAC"
http://www.rcuniverse.com/forum/fb.asp?m=4530191
RE: AMA Insurance Claims
[quote]ORIGINAL: abel_pranger [quote]ORIGINAL: paf <snip> Out of curiosity, I briefly sifted through the Document 500-L. I have couple observations, which seem pretty chilling to me: a) It has expired on March 31st 2006. b) Exclusion T - property damage resulting from radio interference is not covered ! To me, this means once you yell "I AIN'T GOT IT" while flying
Posted on: 6/22/2006 11:58 PM by Author "paf"
in the forum "AMA Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=4420742
RE: AMA Insurance Claims
[quote]ORIGINAL: abel_pranger [quote]ORIGINAL: captinjohn Abel: Sounds like we got the right answer now....thanks. This is good stuff to learn. I believe the AMA is needed. Just wish they had a 6 month price for retired people on a fixed income. I know it worked for me last year....but they put in a one time only thing. For us retired folks it needs to be a lower price. Just about every place or whatever has senior discounts. Not gas though??? Thanks Capt,n [/quote] Capt'n- Well, you didn't exactly get the right direct answer to your question, as we got off on a somewhat tangential topic. Actually, AMA liability insurance will pay for a crashed model airplane (and/or other property damage) due to radio interference, if it occurs during an AMA sanctioned event where a transmitter impound is in effect and the interference is the result of an event organizer error. You indicated that it was a sanctioned event, so the remaining question is did the CD or his helpers goof? If so, the crashed model is covered. The applicable reference is the Westchester liability policy (AMA Doc 500-L on the web site), exclusion T. I hear you on the challenges of living on a fixed income. There is a senior discount for AMA membership, though it isn't as generous as a pro-rated 6 month price. Are you taking advantage of that? Abel [/quote] Out of curiosity, I briefly sifted through the Document 500-L. I have couple observations, which seem pretty chilling to me: a) It has expired on March 31st 2006. b) Exclusion T - property damage resulting from radio interference is not covered ! To me, this means once you yell "I AIN'T GOT IT" while flying, you just lost your AMA insurance and if you hit something, tough luck (as opposed to flying into something by pilot error). c) Personal Injury Exclusion d - excludes a claim between two insured and family members. So if an AMA member hits another AMA member, tough luck. (Seems like Casey got caught up in this one) Who let this ammendment in ???? It renders the whole policy pretty much useless for most of the "got hit by a model airplane" scenarios. d) The first $1,500,000 is payable by AMA directly (think deductible on your car insurance), yet the insurance premium is $840,000 ?? Am I wrong on any of the above ? P.
Posted on: 6/22/2006 2:24 AM by Author "paf"
in the forum "AMA Discussions"
http://www.rcuniverse.com/forum/fb.asp?m=4417479
| 
