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RE: Is there a formula or chart for prop diam/pitch an rpm = HP?
To avoid the Doppler you can put on Pressure Nipple a piezo sensor (microphone) or use the magnet Hall-sensor if it is gaz engine, BUT the error(S) in ordinary hand-held RPM metters which rely on the optical sensor being signalized by the propeller's rotation are not so small. There you get threshold level error(quantazation-error) and although those metters are called "digital" nowadays, still the pattern of the signal is not Square as it is also seen on the picture. Anyway the Oscillograms on the Laptop of tripower222 are nice things, Congratulations ! and surely more precise than hand-held optical rpm-metter. Still 100% accuracy is the always the "dream-never-comes-true" for any engineer; there is always some "bug" in the system. Surely it is good idea to keep the Size and Number of those "bugs" as low as posible but 100% clean room doesn't come at low cost...[;)] ALSO, allmost all (just to be polite and not to say only ALL) Matematical Derivations about any Physics Phenomena are APPROXIMATE because are based on a number of Assumptions and Simplifications. I believe Pe can list many of those behind the formula used. Still there isn't much need to go so precise at least in glow-engines, even 10% precision should be good enough[:D] in other words I do not care much for +/- 5$ if in addition to the 100$ is possible to get 20$ (+/- 5$), i.e. all those measurements (for me at least) are Relative, not Absolute numbers. Of course if the errors gets in the range of +/-15$ out 20$ gain then is getting funny even for a hobby...[sm=spinnyeyes.gif]
Posted on: 11/19/2009 1:04 AM by Author "NikolayTT"
in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9264421
RE: Is there a formula or chart for prop diam/pitch an rpm = HP?
What is wrong with the Slide Rule ? I have one in my pocket ... just beside my Nokia E90 and works faster and better than Calculators build in the Mobile Phones and gives you kind of Vision, not only some borry numbers ...[:D] and does not need a ....battery...[:D] In fact 5% precision is too good. I wander if anyone of us gets the RPM measured that precisely in practice, regardles what the "super precise" RPM metters claim; those metters have error and I wander if that is even less than 5%. Also, even with the same engine and etc. circumstances no one can be sure he will be able to repear with +/- 2.5% (in total 5% !!! span) the measurements for any engine especially glow ones and even gas I believe. For propellers which are not in the table of Pe's Calculator one way, maybe not the best but still works for me, is to use the Fish-scale and "play" a bit with the number of the Propeller Constant so to get the static thurst the same(almost) from the Calculator and Fish-scale. But as mentioned by tripower222 the relative estimates one gets from Pe's calculator even without knowing the exact propeller constant are very(!) useful things, even if they were "off-set" by the incorrect propeller constant. SUGGESTION: - Lets send to Pe our measurement data, as soon as we get new, with all details and then let Pe think and select what he consider reliable to use for further "tuning" the calculator. EVEN IF we send date with some errors, the accumulated database will show the correct direction of further tuning of the calculator constants, if that is at all needed. But at least the LIST of the propellers could be enlarged, for example with the Graupner's G-Sonic; they are comming as a massive "heavy weight" competitor to APCs. Check this LINK please: http://www.rcuniverse.com/forum/m_9235933/anchors_9253447/mpage_1/key_/anchor/tm.htm#9253447 In any case, so far I haven't seen any other calculator which comes near to the Comfort & Precision we get from Pe's. Have anyone seen better calculator or at least a competitive enough ? - if so, please post the link. Nick
Posted on: 11/18/2009 1:33 AM by Author "NikolayTT"
in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9262003
RE: Is there a formula or chart for prop diam/pitch an rpm = HP?
Yes, there we go: http://www.rcuniverse.com/forum/m_9228496/mpage_1/key_/tm.htm
Posted on: 11/16/2009 3:26 PM by Author "NikolayTT"
in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9258133
RE: Need help choosing an engine
It seems that I had similar dilema to resolve some time ago and I made my mistakes. Just to share what I learned: 1. McCulloch 28cc from leaf-blower turns APC 17x6W at 8000-9000 rpm and weight above 1.5-2.0 kg with magnet depending on how much "flesh" one cuts from the body. Replacing the magnet at this small(!) gas engine seems not efficient because the battery is not much lighter than the flywheel, similar is for Zenoah etc. and needs care to be charged while the flywheel is "permanently charged". Using a starter is not such a bit deal; most of us have it and use it unles the engine is so well tuned... 2. For each type engines there is an OPTIMUM displacement and word 'optimum' here is going to cause unger if not clarified; it is quite personal "optimum". For me ALL BOILS DOWN TO POWER-vs-WEIGHT Ratio unless there are too many personal other reasons: A) Glow Engines have their optimum at 26cc developed for F3A. Below that they are a bit too heavy and above that they eath too much fuel (about 2.5 times more than gas ones.). B) Gas Engines seems to have some optimum at about 80cc. 50cc is still too small and 100cc gets a bit too big. After experimenting with toooo many engines I am about to try to sell most of them and retain the only 26cc and to not invest in 80cc-gas - it is leading to too much Side-Costs (model, servos, Car to transport it, and the Smell to save it at home is a problem beside the Fire hazard which is pretty much there when gas is involved.) C) My side"-menu" has bunch of 15cc and few 35cc all glow. Surely my Gas McCulloch will have ot wait till I play enough with the Glow ones and they are not so "oily" if pipe is taken to out of the tail of the engine. Surely I also like the simiplicity of the Glow - that is why so many are with Glow... Well, I will appreciate if someone tells more technical reasons why one should go gas if he wants to stay on modest budget ? Cheers, Nick
Posted on: 11/16/2009 2:20 PM by Author "NikolayTT"
in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9257989
RE: OS 46AX On A Header & Pipe
Hi Guys, I do not have 11x6 but here attached are 13x10 photos; G-sonic hub is same diameter as APC but it is thicker. Also attached are photos of 16x14 G-sonic-pro from different angles. The shape seems not "smooth" a bit 'extravagant'....[sm=shades_smile.gif]
Posted on: 11/14/2009 3:24 PM by Author "NikolayTT"
in the forum "Tachometer Readings"
http://www.rcuniverse.com/forum/fb.asp?m=9253447
RE: What size 2stroke does OS.70FS replace?
As long as the Aviation is about Power-to-Weight Ratios, I would replace it with any good .91 which seems to have the same weight and maybe 2x the power of the .40. - Why not do that is a wander for me; please explain your choices of .40 or even .60 ? - Saving on Fuel or Vibrations or ? ....
Posted on: 10/30/2009 4:36 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9214443
Glow Plugs for RC and non-RC Engines ?
Hi Guys, As seen on the Photos the original Glow Plugs of Rossi were meant to be different for RC and non-RC Engines. The sample is from mid 60's when the Italian Rossi made the speed records history. I have couple questions: 1. What do you think made Rossi producing different plugs for RC and non-RC ? As seen on the back side of the photo, VR1...VR4 go from hot...to...cold and when it comes to RC the engine displacement is not of concern ? Please, try to explain this if you can.[sm=spinnyeyes.gif] 2. How valuable is this glow plug; should I use it or just save it for my (grand) children ?[sm=49_49.gif] Cheers, Nick
Posted on: 10/27/2009 4:08 PM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9206622
RE: Plug temperature
A question: - How Hot are the Non-RC plugs when compared to the RC types ? Anybody has tried some of them for RC flying, please share your observations. Thanks, Nick
Posted on: 10/25/2009 5:48 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9200102
RE: Plug temperature
[quote]ORIGINAL: asmund My oh my, I didn`t know until now how difficult and complex it is to choose a plug for my engines, it is almost rocketscience it seems[sm=lol.gif] I run OS F in all my fourstrokes, they might cost a $ more than others but so what? they last forever, I think I have never blown one of those. In my twostrokes I use whatever I have at hand, mostly OS 8, 5, 3,also the F, Towerplug, Sirio`s, Rossi`s, Mc Coy 59, ASP, and propably lots of others. After a needle tuneup I can hardly tell the difference between them in the air or on the ground (car, boat) I did some peak rpm testing a couple of years ago and in my engines rpm never varied more than max 300 rpm peak no matter what plug I used, so I think for casual sportflying it really doesn`t matter that much[;)] [/quote] That should clearly indicate that with the approaching winter most of us have got more on the talking than on the building and flying side of the life. At least frankly I feel so... and I fully agree that in many cases it is very hard to tell which plug is used if the fuel and the engine are having some kind of "common sense set-up" proportions, i.e. if we stay away of the extreems... It might be good to agree with some of the earlier posts about What each type of enigne wants, i.e. to pay some respect to those who built the engines and wrote the manuals... I am afraid some of them are looking with pitty at some of the statements at RCU and let us talking endlessly here without even writing a single word (at least I know one guy like that from a very advanced RC engine making company; he is even wandering how we can spend so much time & money to re-discover the Universe ... How is the weather in Norway ? Here we got already the first snow flakes but still is above the freesing point and ... I keep writing instead of flying .... Nick
Posted on: 10/25/2009 5:42 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9200099
RE: Plug temperature
Dar, Is it F so hot or it is massive to retain the temperature, or both ? - please specify. Nick
Posted on: 10/25/2009 3:43 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9200029
RE: Plug temperature
Bob, I imagine (but it is your jusdgement) that you can increase pretty much the precision of your measurements in the following manner: 1. Get a stroboscop from the car guys which is used to see the ignition instance, or use a photo-flash. 2. Drill and place a nipple beside the glow plug and use that pressure to trigger the stroboscope. 3. Then instead of propeller place a heavy wheel like those used for the boar engines. Behind or in front of it place a disk on which outer surface you mark every 1mm axial line for about one half inch distance. So the idea is pretty classic one: - when the pressure in the head chamber triggers the flash then you will see which mark on the disk is seen due to the stroboscopic effect. With different plugs you should be able to see different mark on the disk and from there you will find which plug is hotter = it should flash the earlier mark on the disk, isn't it. Check also my post earlier today. Using that old DDR-idea you can install second plug on the head of your engine, drill it trough and fill it with transparent material, like melted quartz. Then you will see what is going on inside of the head-chamber of your engine... It is amazing thing ... Of course the professional laboratories for engine research have much more precise instruments. For example, why not visiting the nearest University, I believe that is University of Dallas or Texas A&M university and ask if they have some lab where the undergrad students will enjoy having a course project and measure some bunch of glow plugs for you. For sure in those Universities there are many who are at least interested also in RC flying. Cheers, Nick
Posted on: 10/24/2009 12:55 PM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9198510
RE: Plug temperature
Guys, It seems Friday-night is getting to the "detonation" point ... and your "engines" get overheated ... [sm=punching.gif] Maybe it is better go dancing in Friday night, please the girls and not take much "heavy" fuel...[sm=spinnyeyes.gif] because the morning will be more painful ... Anyway Ethanol is not so bad for the health and in good proportions cools the "engine" down ... I think ... you migth agree...[sm=thumbup.gif] Proportions(!) are the essense of life ... Back to topic please: There were in mid 60's (obviously I am getting older...) some Glow Plugs made in the former East Germany which on the top were filied with transparent insulator so one can see the COLOR, i.e. the temperature can be measured by some kind of pirometer. That time many were runnig also with open exhaust so one can see how much "orange or red or yelow" the plug is... So QUESTION: - How nowadays one measures the TEMPERATURE OF THE PLUG ? - please give some Technical Details. Anyone have seen those Glow-plugs arround? - I have one somewhere in my storage and if I find it I will light it for you and make a photo, but I would like to buy some more of those if they are made somewhere; please advice. After burning maybe some N x 10 plugs of different kind I use only F type and adjust the rest to the plug, i.e. "manipulate" 1)The Fuel and 2)The Compression ratio(the shim). And seems the Glow engines have pretty "flath" optimum of the set-up so they can take a lot of unsuitable mix of "things" but seems the professionals make it always better than the others... I wander How Many Super-Electronically Enhanced Engines OS managed to sale; any idea ? Thanks, Nick
Posted on: 10/24/2009 12:19 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9197511
RE: Plug temperature
[quote]ORIGINAL: jeffie8696 IÂ always use the hottest plug IÂ can in order to keep the idle and transition smooth. [/quote] But that is on the ground... I would go "one step back" to the colder one so to give some "advance" to the ignition instance when the RPMs get higher in the air, of course if the high-rpm is the goal. OK?
Posted on: 10/23/2009 10:29 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9195798
RE: Plug temperature
Well, that is difficult question. In fact what I am doing when I have unknown engine and/or the air temperature and humidity are unusual etc uncertainities, and if the nitro is below 5% in the fuel then I would start with A3 which seems hot, but if the nitro 5-10% then OS-8 and if nitro is more than 10% then A5. The temperature of the plug is not so critical and if you do not have hot enough plug - then you can take away the shim under he engine head - then check the RPM and if they are about 300-500 higher with the same propeller then you need hotter plug or you need to add nitro in the fuel and then place the shim back and check. You can check the OS web pages, I think there was a diagram which g-plug is for what. Danger: - Some fuels have incompatibility of the synthetic oil to Castor. The TROUBLE is that if you add Castor then the fuel which needs HOT plug will need very COLD plug because the mix of synthetic(some types) and castor oil leads to detonation which in case of hot plug can bust your engine in various ways (overheating etc.) Thus do not rely that all is done by the Temperature of the plug...
Posted on: 10/23/2009 10:23 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9195782
RE: Super Tigre prices appear to be heading up
Hi Guys, All seems to be about the cross-cultural differences. I have number of Italian Super Tigre engines and as well number of Japanese OS, and quite a few MVVS and Webra. Looking at the original rign versions of ST.46 and OS.50 the performance is quite the same but the OS last maybe 5 times longer ... surely it is heavier but robust and takes lot of "punishment". Then we got the Chinese Guys on board and the life became such a mixture of cultures and so the Chinese ST is ... and no hope to get the ST better while OS is ruining their quaity and there are many junky new engines coming on the market. Maybe you should consider buying more European RC engines and ... cars... Try MVVS for 26cc and Webra for all displacements and see the differences with new-ST and new-OS... Of course better wait till the US dollar exchange rates get back to "normal". [;)] Nick
Posted on: 10/22/2009 11:28 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9192703
RE: Is this the F3A which one would like to have ?
Thanks, I will do it right now. Nick
Posted on: 10/22/2009 10:46 AM by Author "NikolayTT"
in the forum "Classic Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9193296
Is this the F3A which one would like to have ?
Hi Guys, I came accross the CMPro's model of F3A: http://www.cmpairplane.com/aerobatic/Leo.html and I am wondering if it is good idea to buy it and power it up with 26cc-2S engine ? Looks cool, but the outlook is not everything indeed. Anybody experienced with this one up there ? Please advice. Thanks, Nick PS. I have just found an old link which is pretty interesting too: http://www.rcuniverse.com/forum/m_7994067/anchors_8702310/mpage_3/key_/anchor/tm.htm#8702310
Posted on: 10/22/2009 10:43 AM by Author "NikolayTT"
in the forum "Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9193290
RE: CMP - Leo 110
Hi Guys, Out of quite many links, here is one about Leo 110 which seems very good to read, especially this page 3 http://www.rcuniverse.com/forum/m_7994067/mpage_3/key_/tm.htm
Posted on: 10/22/2009 10:41 AM by Author "NikolayTT"
in the forum "Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9193283
RE: CMP - Leo 110
Thanks Guille ! Great Photos of Nice Plane and your Co-pilots are so sweet ! Congratulations !!! Nick
Posted on: 10/22/2009 10:11 AM by Author "NikolayTT"
in the forum "Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9193234
RE: CMP - Leo 110
Hi Guille, Could you post some links for Accipiter, Venus and also Leo; there are too many links comming from Google for example for Accipiter... Thanks, Nick
Posted on: 10/22/2009 9:41 AM by Author "NikolayTT"
in the forum "Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9193173
Is this the F3A which one would like to have ?
Hi Guys, I came accross the CMPro's model of F3A: http://www.cmpairplane.com/aerobatic/Leo.html and I am wondering if it is good idea to buy it and power it up with 26cc-2S engine ? Looks cool, but the outlook is not everything indeed. Anybody exprienced with this one up there ? Please advice. Thanks, Nick
Posted on: 10/22/2009 1:44 AM by Author "NikolayTT"
in the forum "Classic Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9192717
RE: OS-81a Engine question
I wander why not going to .91 or similar because after all the weight of 0.61 and 0.91 are quite the same while the power is almost double for .91 and for any plane power/weight ratio is the most critical thing. Of course the fuel tank should be bigger and the the vibrations might be bigger too. I have some experience with 0.5 engines but they are really small for 3D unless the plane is small and light. Well, everthing is of course subjective when it comes to stability of the flight... Cheers, Nick
Posted on: 10/21/2009 3:15 PM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9191232
F3A and ARF, is there anyone like that ?
Hi Fellows, Having not much time for building nice F3A airplane I wander if it is possible to find some Almost-Ready-to-Fly one, which is of very good quality; I have couple of standard ARFs but they are near to junk-quality. - To ask the question in a different way: - Which kit or even ARF you would advice me to look at which is good enough for F3A ? The engines I have for this tasks are: OS.91FX, Webra-15cc, MVVS(Evolution)-26cc and OS-BGX-1. Hoping to get some nice ideas, as usual on RCU, Thanks, Nick
Posted on: 10/21/2009 12:55 PM by Author "NikolayTT"
in the forum "Classic Pattern Flying"
http://www.rcuniverse.com/forum/fb.asp?m=9190904
Best F1 airplane for 26cc Engine
Hi Fellows, After many discussions it seems (to me at least) that best Power/Weight ratios are achived by the 26cc Glow and 80cc Gaz Engines. While 80cc is requiring too extensive investment, and also I have MVVS(Evolution)26cc glow engine, I would like to ask if you could suggest some RC planes suitable for 26cc size engines. Thanks, Nick
Posted on: 10/21/2009 10:15 AM by Author "NikolayTT"
in the forum "Scale Racing"
http://www.rcuniverse.com/forum/fb.asp?m=9190559
RE: Faster Flying wth MVVS-26GFS; - What set-up ?
Thanks Pe, I just simply didn't think yet about the cooling...
Posted on: 10/21/2009 9:40 AM by Author "NikolayTT"
in the forum "MVVS Support"
http://www.rcuniverse.com/forum/fb.asp?m=9190499
RE: Faster Flying wth MVVS-26GFS; - What set-up ?
Yes Pe, Tuning of the pipe seems (to my limited experience) pretty dfficult job and MVVS have been doing very much work obviously on that. Also the price of the Macs pipes is almost twice higher. Looking in the dimensions it seems the Macs 23" lenght without mufler is equal to the MVVS with mufler section... That rises the Question: - While cuttng off the mufler section of the MVVS pipe it is maybe needed to consider the "kick-back" effect of the pressure accumulated there on the pressure in the resonance compartment, and then on processes in that compartment. Certainly, this will change the pattern of the waves in te resonance section and thus the MVVS power boost effect might be influenced more by the disk reflector while there isn't a mufler section... In order to be fair to Macs and MVVS maybe I should think that I am not comparing anymore MVVS original pipe with Macs but a MVVS modified (damaged by me cutting off mufler) one. In this sense it might be the case that Macs gives more power than the MVVS-modified on, what do you think ? P.S. In other words, I wander if in the Tutorial below was the right thing to cut out the whole mufller section; why not about the 'half' of it or to cut piece-by-pice and watch te power boost so to account for the new constellation of the processes in the resonance pipe ? http://tech.flygsw.org/all_about_evolution_26_gt.htm I hope all this makes good sense also for the Scale-Ricing guys which as Pe suggested have been very mich talking about F1 raing with Sundowner and using MVVS/Evolution 26 or 35. But I do no know how to link those two forums so the current discussion appears in the Scale-Racing too; please advice. It seems Very Hot Discussion at http://www.rcuniverse.com/forum/m_5704069/anchors_9190172/mpage_10/key_/anchor/tm.htm#9190172 Nick
Posted on: 10/21/2009 4:16 AM by Author "NikolayTT"
in the forum "MVVS Support"
http://www.rcuniverse.com/forum/fb.asp?m=9190153
RE: Sundowner from Hangar 9
Hi Fellows, Your input is very much missed at http://www.rcuniverse.com/forum/m_9143474/anchors_9190153/mpage_1/key_/anchor/tm.htm#9190153 or you can maybe advice me how to link those two dicussions ? Thanks, Nick
Posted on: 10/21/2009 4:15 AM by Author "NikolayTT"
in the forum "Scale Racing"
http://www.rcuniverse.com/forum/fb.asp?m=9190172
RE: Copperhead Venom 45
Sorry, was wrong post
Posted on: 10/21/2009 4:13 AM by Author "NikolayTT"
in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9190170
RE: Super Tigre prices appear to be heading up
Tower might have no choice. And also there is so much junk comming nowadays on the market so the relative quality of ST is relatively going up anyway and the ST guys have their rights to lift the price up. I like especally G-2300 but I just got a brand new MVVS-26 glow so I can wait till the ST prices go down next time or to get some new improved type of ST, which might consider fixing their fault to make 23cc instead of 26cc. Another reason for ST prices going up seems to be that good quality OS engines were stoped in production (50SF, 91FX etc, you might agree) and OS tries to save too much while keeping the prices going up anyway.[:D] Nick
Posted on: 10/21/2009 3:32 AM by Author "NikolayTT"
in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9190143
RE: Faster Flying wth MVVS-26GFS; - What set-up ?
After reading the http://tech.flygsw.org/all_about_evolution_26_gt.htm (mark Fuess) as said it is very good advice how to do it. But I got a bit confised. I was expecting to see that there is reverse conical surface in the MVVS mufler but it appered to be just disk. Surely it has been well experimented and tuned to fit the MVVS26. The question in my mind is: - Would be biger boost of the power if I would use the classis two-cones reso-pipe of Macs, for example in http://www.macspro.com/tunedpipes.asp the models # 1195 or # 1196. Maybe you or some of your contacts have tired those on MVVS-26 ? - please comment. Thanks, Nick
Posted on: 10/20/2009 2:58 PM by Author "NikolayTT"
in the forum "MVVS Support"
http://www.rcuniverse.com/forum/fb.asp?m=9188520
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