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RE: Dirty Birdy build
Tim, What Dave said. Whenever possible, always use urethane for CC. KK epoxy clear is not meant for top coating and if it is, it shouldn't. The advantage of an acrylic urethane top coat is that it should reduce the rate of UV degradation of the color coats - a common problem with epoxy based pigments - especially white. We've all seen what happens to Hobbypoxy and K&B epoxy finishes after 10-20 years... White fuses then are I'll beige today. BTW, be covered hair to toe when shooting isocynates (acrylic urethane). You will absorb the overspray otherwise and we don't want to discuss that... David PS DuPont and Sherwin Williams also have equivalent products. Probably the most expensive paint you'll use on a model.
Posted on: 6/17/2013 8:55 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11545773
RE: Remake of MK Kits from Naruke
Steven, Thanks. I'm still on my phone so a more detailed comment on my part will have to wait. That said, would it be possible to get the folks who [i]would[/i] coordinate (Chuck?) the effort involved here? It might lend itself to a more direct path to the intended goal and less hearsay. Just wondering. David
Posted on: 6/16/2013 12:24 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11544976
RE: Remake of MK Kits from Naruke
Steven, Not to sound negative about it as I think the re-release of MK kits would be just peachy but as presented, it all sounds a bit weird for lack of a better word. I'm going to sleep on it to form a somewhat more intelligent reply. David
Posted on: 6/15/2013 9:52 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11544544
RE: Dirty Birdy build
Tim, I don't think one can sand KK without loosing its fuel proofness. It would be good to check with the KK experts. But..., you can always sand it all down smooth, uniform and thin and then clear it. Weight would be the same or likely lighter. Just an idea, David
Posted on: 6/15/2013 7:42 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11544445
RE: Dirty Birdy build
Tim, Is this KlassKote? If not, I was going to suggest skipping the "knife". Wet sand the smithereens out of it. It will go all dull on you but that's good - it will give you an ideal and light base coat for a final acrylic urethane top coat. That one, you really don't want junk on! David
Posted on: 6/15/2013 4:07 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11544267
RE: YS60FR (H) conversion
Matt, No, not for certain but I don't think there is any crossover of parts between old FS/FR engines and the new classic. If there is any crossover, it would be with the R/AR long strokes. The same case is used at least dimensionally (the mold might be slightly different haven't gotten a classic yet). But other than the case, bearings and maybe gaskets I don't think anything can be interchanged. Maybe the cranks but I doubt it. The carbs are different. What really is needed is a review of the classic and a comparison to the old engines, both short and long. We'll soon have classics now that they're here. Looking forward to seeing that Arrow! Are you building the fuse in wood? David
Posted on: 6/14/2013 7:34 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11543612
RE: YS60FR (H) conversion
Steven, I see your point and yes, it would be tricky to adjust once mounted in a non glass cowled fuse configuration. My thinking was that one would tune the engine on the stand and that further adjustment might not be needed. However, one possibility might be to develop some kind of tool that would allow rotation of the knob through a hole. On the other hand, swapping for an AC version might not be an issue. As far as I can tell, there is no other difference between the two engines other than the ringed Piston and bridged exhaust sleeve and the short shaft. I might be jumping the gun though. I don't have an AC 60FS so I can't properly compare. As far as the shaft goes, I don't follow the idea of moving it "closer". It goes where it goes based on drive washer exposure from the fuse. The shaft is just too short to accommodate a spinner backplate, prop and adapter but the TT SS adapter should take care of it barring the swap for an AC shaft. David
Posted on: 6/14/2013 7:23 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11543609
RE: YS60FR (H) conversion
Steven, I have one of the old but new ringed YS60 FS-H's as well. I didn't see any need for changing the knurled mixture screw on the bottom for the standard aircraft version but what is needed is some way to make the shaft a little longer so that both a prop and a spinner can be mounted on it. They are shorter shafts than the air versions. Other than replacing the shaft with an air version (which I assume works but timing might be an issue), a solution is to use a TT shaft extension adapter kit which locks on to the threads by boring through the prop. So with the backplate and prop mounted, there are no exposed threads for a regular adapter to be used but if one used the threads "inside" the prop hub, it can be used as one might. That said, I'm all ears for any other insight or info that can be shed on the subject. Indeed I'm curious as to how these ringed heli engines compare to the new classic short stroke which in a sense is also a heli ringed engine which was adapted for patter use with a RE case... David
Posted on: 6/14/2013 12:54 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11543359
RE: Remake of MK Kits from Naruke
What happened here? Sounds interesting! David
Posted on: 6/13/2013 3:47 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11542540
RE: Motor Mount for New Nova Rossi Speed/13
So this means that the OS, Rossi and NovaRossi all have the same lug mounting dimensions. Make sense Dave? David
Posted on: 6/7/2013 4:35 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11536714
RE: Dirty Birdy 40 - Laser Kit
One thing's for sure... time flies almost better than classics! All kit builders, my apologies for the delay with these documents - here they are. The first PDF is the laser kit parts list with the same key etched on to the laser cut parts. Items in roman numerals denote balsa that is to be supplied by the builder (standard sheet and stick stock mostly). The second is a brief PDF of the equipment and hardware needed to complete the build. Not rocket science for us classic builders but hopefully of some help nonetheless. I look forward to seeing some build pictures! Anyone out there gotten a start? David
Posted on: 6/7/2013 12:44 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11536450
RE: Starting out in RC again
[quote]ORIGINAL: mmabc I'm curious how this impacts a trainer slave setup? I learned on mode 4, but I don't want to teach anyone mode 4. I'll want the slave radio set to mode 2, and the master set to mode 4. Anyone know if I can do that? [/quote] It shouldn't. What pot is used to control what channel is encoded is simply a mechanical issue. In the old days as you say you needed to swap pot solder points because the channels were hard coded to a conduit. Nowadays the "swapping" is done electronically. As you remap the aileron to the left horizontal pot from the right (and vice versa for rudder), the encoder knows where to [i]receive[/i] the input from on a specific channel. So if aileron is assigned channel 1 by your manufacturer, channel 1 is encoded to the Tx from the preset stick and sent over RF to the Rx. In a trainer setup, it is simply a matter of [i]which[/i] encoder is used to control the channels. If encoder A (the instructor) is used, the instructor's channel encoding is sent to the transmitting RF. If the student's encoder is used, that encoders mapping is sent over to the instructors RF deck. What sticks happen to be used on each transmitter is strictly a local thing. The Rx knows nothing about that nor does it care. It just reads "Ch 1, +2.3V - go"... so to speak. [quote] One other question. I was looking on craigslist yesterday. It might interesting to buy out someone with an upgraded trainer, plus a radio and other accessories I need.  I saw a bunch of folks with 72Mhz radios. What's the story on that?  I see the new ones are 2.4Ghz. That was one of the final straws that took me out of RC when they changed the frequencies and I would have to replace my $500 radio. Are the 72Mhz radios still in use legitimately? [/quote] It might just be me but I wouldn't buy someone else's trainer unless I'd seen it fly and probably knew the person selling it. I also wouldn't recommend buying used 72 MHz equipment today (unless there is a specific reason like wanting to convert old well build joy stick radios to modern encoders and 2.4 decks). New 2.4 radio equipment is just so reasonably priced today that buying used 72 is not only a [i]no warrantee[/i] proposition but it also is investing in deprecated equipment. You can spend as little as $50 on a new 4-5 channel 2.4 Tx. Receivers and servos are typically bought separately in any case so there is no huge added benefit from buying a complete radio system today. With ~$250-350, a new 7 or 8 channel Tx can be bought. While it is not necessary at first, it quickly becomes useful to have a few extra channels and the associated programming ability of those radios. For a lower start up cost, a 5-6 channel Tx is the way to go. That said, 72 MHz is a legal band today but the frequency separation is narrower than before the days of PCM (which was typically also 72 just encoded in a "digital" way). In order for any Tx and Rx to be AMA or MAAC legal on the 72 MHz band, they have to be "narrow band" compliant. In most cases, it is easier to use a modern inexpensive 2.4 band RF deck even if one wants to continue using older encoder and stick/switch Transmitters (e..g, Kraft, ProLine and the like). David
Posted on: 6/5/2013 3:36 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11534468
RE: Curare construction ARG
Does indeed! That's a Curare. Diego, if you're going to glass prior to paint, just watch the resin on the fin. Due to the grain direction of the sheeting, there is potential for the wood to warp (or sink) between the ribs under the heat of the epoxy curing. I'd suggest using cut back laminating epoxy (using 90%+ denatured alcohol) to just adhere the cloth to the fin. Once this thin first layer has cured, you can "re-paint" uncut laminating epoxy on to the glassed surface to make sure all the cloth is thoroughly bonded and whetted out. This should help to prevent the wood from absorbing too much epoxy at first and potentially warping. David
Posted on: 6/5/2013 2:59 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11534436
RE: Ursa major 25
Nice! Jason, congratulations on a pair of great little classics. Enjoy them! I haven't tried them yet but I got some Falcon wood props recently. I also picked up some Xoar wood props. I'm going to be running them in a 60 and let you know what I think of them. The Falcon's look promising although until they're flown I won't know how well they pull (wish I at least had a way to measure thrust on the bench). David
Posted on: 6/5/2013 2:47 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11534423
RE: Ursa major 25
Outstanding Jason! How do you like them 32 SX's? What fuel are you running in them? Are you turning 9x6's, 9x7's? They can also turn 10x6's well but ground clearance is the issue with these beautes! How do you feel the Curare 20 compares to your 60 size? Faster no doubt but does it have a similar control response albeit a little more nervous perhaps? David
Posted on: 6/5/2013 12:10 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11534286
RE: MK Curare 20 build.
Jason, is she airborne? At 4' plus and a 32 I bet they are like JetCat powered models... [:D] David
Posted on: 6/5/2013 9:54 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11534147
RE: Ursa major 25
Jason, given your recent "off forum" exchange I thought it would be a good time to bump your threads to see how the two little bullets are flying. I look forward to an update and some at the field shots. Cheers, David
Posted on: 6/5/2013 9:48 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11534144
RE: Curare construction ARG
Chino, Looking forward to its completion! For future reference, sheeting on the fin should have grain parallel to either the LE or the TE (ideally a mix of both) just like when you build a framed up wing or stab. Sheeting parallel to the thrust line results in a weaker structure which can more easily break in its span wise direction in the case of a flip over. The same goes for the rudder unless you want a warped control down the line. Do you plan to paint this austral winter? David
Posted on: 6/4/2013 5:17 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11533483
RE: Classic 40/45 power choice?
[quote]ORIGINAL: EscapeFlyer I am eager to get a NR Pylon 46 from him as well! Brian [/quote] Brian, from what I hear, you're going to love your new Nova Rossi's. The 46 sounds like even more of a beast than the 61's. Great engine to put into a [i]little[/i] Escape! Just scale it down a tad and use the same canopy. The DB40 and 60 use the same canopy so no reason the Escape shouldn't... [:)] David
Posted on: 6/3/2013 7:33 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11532521
RE: Starting out in RC again
Flying mode 4 today only requires plugging in your rudder servo into the aileron Rx channel and vice versa. Programming of switches on Futaba (although I'm not a user) should allow you to set things like dual rate switches, mixing and so forth. The only hassle may be that you have to think rudder everywhere it says aileron and vice versa. It should be a simple fix for Futaba to supply you with an M4 Tx. It's a software variable swap, recompile and firmware zap. I learned on M1 and made the switch to M2. M4 for an M1 flyer is akin to flying standing on your head... [&:] Can't quite fathom it... David PS Welcome back!
Posted on: 6/3/2013 12:33 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11532094
RE: please help identify this plane
It would be worth checking out Joe's original framed-up article pictures (they were in colour and in RCM if memory serves) as they show the model as he first envisioned it. I seem to recall it being pretty arrow shaped in the tail boom which is often where we note whether a builder did a 1/4" radius or took the filthy bird to task as it ought to! [:)] One of the things I decided to change in the re-design of the DB40 for laser kits was to swap out the top tristock (which was 3/8" originally I believe) for 1/2" stock. While this may seem like a lot of unnecessary dead wood, the idea is for it to be sanded to the limit while still retaining a surface of contact between the stock and the top and side sheets. Some like to paint their tristock to measure the extend they've gone deep into it - not a bad idea although I've never tried it. Regardless, each builders dirty bird will vary is shape and contour based on their comfort level and skill in shaping a box like fuse. I think for this reason we see many wood fuses that are more boxy in shape compared to the glass versions (of the DB60 - I've never seen a glass DB40 or DB20 for that matter) whose shape remained constant in that which was given by the builder of the original plug - as Bryan rightly points out. Attached are two pictures of Greg's nicely produced DB60's back in the day. He'd have to clarify whether these were glass or wood fuses but in either case, they are both very nicely contoured fuses. Last picture is of a Trenton DB40 which also has a nicely sculpted wood fuse. David
Posted on: 6/2/2013 2:22 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11531085
RE: Vote for 40/45 classic rekit design
Sure thing Tim. Here's the essence of it. What remains to be done (probably mentioned before) are the wing and stab airfoil work - that is, ribs. I'm pretty happy with the way the fuse is re-drawn to go together interlocking formers with a 1/8" lite ply doubler (instead of standard 1/8" ply) and 1/8" fuse sides instead of 3/16". The formers are also all 1/8" ply either standard or lite. Wing and stab would both be fully sheeted although one can easily modifiy the wing to be partially sheeted and use cap strips over the outer ribs if one plans to use plastic covering. Flaps naturally are also an option. Power recommended would be a YS 45 FR, OS 46 VF(-P), NR R46 RE or a Rossi R45 RE. The one point worth noting is that per the design, the fuel tank level resides fairly low compared to the height of the carb so a metered fuel engine is not a bad idea. That said, it could be that some of the engines including the NR may perform just fine despite the relative location of the fuel tank. While the stab and wing require some careful building (I'd probably produce ribs holes that would permit jig built surfaces), the fuse should [i]snap together[/i] pretty easily with the majority of the work being in the carving of the "cowl" area forward of the FW and the fin LE blocks which is actually rather straight forward. Other than that, the fuse is pretty much a box with a very long glass deck somewhat akin to the Magic. I believe I managed to make provisions in the re-design for a 12 oz Hayes slim tank but I'll have to check that. A maximum of 3 servos in the wing (ailerons and flaps) and 4 in the fuse will require a 7 channel Rx. The design would also include a plywood (3 x 1/8" ply laminate) engine mount with the engine bolting down on to thin aluminum plates. Any questions, please shoot! David P.S. It's a 52" length 60" span bird so it's not small for a 45 size machine!
Posted on: 6/2/2013 2:09 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11531074
RE: please help identify this plane
Brian, Are you sure the RCM plans present a more rounded version than the original glass version. I've always believed the glass fuses were the most tear drop in shape. David
Posted on: 6/2/2013 5:08 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11530669
RE: Gaskets for Webra 60 Speed 60 RE
Steven, Another option would be to trace the outline of the rear of the crankcase front and draw the circular holes for passage and bolts by simple measurement. Once you have the template, it can be re-drawn for symmetry in CAD and sent to the guy who sells gaskets on the auction site. I think he cuts them with a laser. The good news is that the Webra Speed Champion (SE) and the Speed Racing (RE LS and SS) use the same gaskets so they are quite useful. Maybe the auction site guy will start selling engine gaskets in addition to exhaust ones. David
Posted on: 6/1/2013 8:48 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11529908
RE: a few questions following the MINARE's maiden flight
Good point Ed. A cure for this syndrome is to build the model lighter. This can be achieved through thinner "shell" frame ups and the use of lighter mini and micro servos (e.g., throttle, retract valve) instead of standard servos which are not needed. At sub 5 lbs all up, a full house 45 size model is relatively light (wing loading wise) compared to an 8 lb 60 size classic. Even at 6 lbs larger 45 size designs such as Autora's, Dash-5's and Citations are quite light given their wing area. On the upside, these same models fly comparably to their larger 60 size brethren, consume less fuel and have a higher power to weight ratio. To my mind, this makes them excellent pattern [i]trainers[/i] and are a tad lighter on the wallet. At 5 lbs, Paul has done well with a glass/foam painted piped Minare. However, as we know the Curare is the quintessential ballistic design. David
Posted on: 6/1/2013 7:59 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11529870
RE: please help identify this plane
Paul, It's a wood framed up Dirty Birdy. Either a 40 or a 60 but judging from the stab its a 60. The canopy shape is not right. You can get the correct one from Keith at Park Flyer Plastics. I would partially paint the canopy so it doesn't look like bubble out of place sitting atop the fuse... What's for power up front? David
Posted on: 5/31/2013 9:00 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11529564
RE: Vote for 40/45 classic rekit design
How about now Tim? [8D] Oops! Well, this is RCU. You know how it is with image uploads. If we have planetary conjunction, then it's good to go, otherwise? You're SOL... [:)] David
Posted on: 5/31/2013 1:57 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11528239
RE: Vote for 40/45 classic rekit design
[quote]ORIGINAL: tgwhitley Poll voters It does seem the voting has slowed down in the poll. I would favor a Citation, which was also my vote, but cost might be factor. [/quote] Tim, the cost of kits does vary based on design (how much laser cutting there is) but obviously also on whether they have foam core surfaces vs framed up and whether there are any glass and plastic parts in the kit. Plastic is generally limited to canopies and as was done with the DB40, I favor the canopies being sourced by individual builders. This keeps the shipping costs down and they are reasonably priced to start with thanks to Keith at PFP's. Since these would be laser cut "short" kits (not complete kits and hardware is not included) they can't really be compared to original MK, IM or Yoshioka kits. That said, the cost of these short kits is a fraction of what the originals kit cost was when it was in production not to mention the auction cost they now sell for if one happens to be offered. With that in mind, I'm thrilled to be able to re-draft these designs with little improvements/changes and be able to build them despite them now being long out of production. [quote] Would the difference between the top 3 designs to kit cost be minimal? I do believe that the kit should be design that will be worth effort to produce in numbers sold. Does the voters and interested parties think new thread for this topic? Thanks for voting Tim [/quote] It's hard to know what the difference in price between the three top designs would be (until the work is done and they are kitted) but I can say that the Tipo 40 would be a fuse/vertical only design and the wing & stab would be foam core. This may add somewhat to the cost if one is sourcing the cores since there is an additional shipping cost involved. Cores are also a tad more expensive than the equivalent laser cut wood for a framed up wing. On the other hand, if one has the equipment for cutting one's cores, then the cost is lower as there is less material and cutting for the kit compared to a framed up wing and stab. As for the Blue Angel and Citation, both had framed up surfaces in the originals. My inclination would be to keep them as such in order to make the kit more "self contained" and lower the overall shipping. These two would therefore have more expensive [i]laser kits[/i] compared to the Tipo but they would also be a "one box kit". All wood kits are in general less expensive than those that have foam core surfaces. Finally, in the case of the Citation, there would be the cost of the glass deck. However, the mold is made (kindly by Don) and being able to re-construct this classic is rather unique. It also makes for a very nice model setup which is easy to maintain and assemble at the field since the exhaust is permanently installed in the model. Given that there is reasonable interest in the Citation and I'm interested in building one myself, I will likely go ahead and get that one done when time allows. It is also quite advanced in terms of its design stage (wing and stab frame up is left to do) so I should be able to get it done sooner than the others. The likely availability of the new NR 45 RE (a pattern prototype at this stage I believe) also makes the model a more feasible project for those who would like to use a current production powerful RE 45 - something needed for this larger 45 size design. As for kit cost, what would be helpful is having a "happy figure" from anyone who is potentially interested in a kit. In other words, a price point that would compel you to pick up and build a kit. This was done with the DB40 and helped to establish both the feasibility of the project as well as a price point that most everyone was happy with. So anyone who's interested in the Citation 45, please feel free to send me a PM (on RCU) with your thoughts. TIA, David
Posted on: 5/30/2013 1:48 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11528104
RE: header length for pattern - max RPM or not
Paul, By the way, 5 lbs dry all up is very good weight for a piped 50 powered painted glass/foam Minare. Testament to the remarkable low weight of the engine as well as good finishing skills! Are there retracts on your model? David
Posted on: 5/28/2013 10:09 AM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11525544
RE: header length for pattern - max RPM or not
Paul, We might be starting to loose track of your threads (at least I am, not that it matters I suppose). Just a suggestion: it might be easier to have an ongoing discussion about your Minare and the engine setup if you concentrate on a single thread. I believe there are now 4 threads with a few posts and things may be getting "lost in translation", so to speak. Anyhow, Dick's advice offered above is always nice to have. Someone with much experience with this type of engine and this type of pattern design in particular. For reference, Dick Hanson is the designer of the venerable Tiporare - a variation on the Prettner Curare. Getting back to your engine, I read in your other thread that you "cut your pipe". I'm not sure if this means that you actually cut the pipe inlet (presumably) or just cut the overall length of the exhaust in the header length (although in this thread you suggest that you haven't cut the header). It is always a good idea to cut the header to tune the exhaust rather than the pipe as the latter will affect the expansion chamber volume and resonance behavior of the pipe. Reducing this in an 8.5cc pipe may effectively turn it into a 6.5 or 7.5 cc pipe. I've never done that or seen others do it so I don't really know how a pipe would behave if it were cut substantially at the inlet. Other than the good tips suggested by Dick above, I am aware of others using the Macs 8.5 QP on an OS 55 AX and commenting that while this pipe resulted in more power (higher rpm), it was less "usable" as the throttle response was rather "peaky" with a less friendly power band. Instead, the 10 cc QP was favored and resulted in the engine behaving much better. The Webra 50 is slightly smaller than the OS 55 but it may respond in a similar way and using the longer 10 cc pipe may work out better. I've also attached a review of your engine which you may find interesting. You will note that you are getting 1300 more rpm than Clarence Lee did in his tests. This difference makes sense considering his figures are using a Webra muffler and of course your plug, prop and fuel are different. Those differences aside though his tests yielded 14,200 on a Rev-Up 11x6. Given that, it seems that you could stand to loose 300-500 rpm on a slightly longer pipe setup (either different pipe or simply longer exhaust) and have a more reliable engine. At 5 lbs, your model should still have plenty of thrust in uplines on the APC 10x7. I would also try the 11x6 although this will require a longer exhaust setup yet. You might get ~13K+ on that prop when tuned. As a point of interest, the recommended engine for the new Austrian Curare 60 ARF is the OS 55 (not the 65). I believe that model weighs around 7 lbs all up so your Webra 50 on a 2 lb lighter (and smaller) model is surely an impressive setup! David
Posted on: 5/27/2013 1:12 PM by Author "doxilia"
in the forum "Classic RC Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=11524621
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