RE: Can I use a Graupner 12.5x7 - 3 blade on a YS63?
My Saito 100 swings the Graupner 12.5 x 7 3-blade at 10200 rpm peak, the same rpm it swings MA 14x7 prop. So this prop is definitely too big for YS 63. Graupner's 11x7 3-blade is perfect load for YS 63. If you want larger diameter, MA 12x6 3-blade should also work pretty well. If you don't like the color, they paint pretty well.
Posted on: 9/21/2007 7:33 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6397980

RE: 1 horsepower, really the power of a horse?
[quote]ORIGINAL: jaka Hi! 1 horse power= lifting 75kg , 1m, in one second. Try it... Don't think anyone will make it... [/quote] I think 1 pony can lift 50 kg 1 meter high in 1 second. I can probably make it with leg press. Does that make me a pony?[:D]
Posted on: 9/3/2007 11:15 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6324626

RE: saito's 220 large bore carb & pump
I tested the Master Airscrew Classic 20x6 today. It seems to peak at about 8000 rpm, with the main needle at 2 turns out from fully closed. The engine seems to be real happy with this prop, as opposed to the Biela 20x6, which struggles to reach 7500 rpm, and need the needle to be 3 turns out from fully closed. The MA Classic 20x6 has great thrust too. The only draw back is its heavy weight, as I can notice a slight spool up delay. For those of you who have good luck with Biela 20x6, I suspect that my carb is not getting enough fuel. I have a real simple fuel setup, with standard muffler pressure, on a profile plane. My fuel is 30% nitro heli fuel. I wonder if it could be the cause. What nitro are you guys using?
Posted on: 7/15/2007 10:40 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6115732

RE: saito's 220 large bore carb & pump
I recall my APC 19x8W peaking at 8000 rpm.
Posted on: 7/13/2007 11:14 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6108625

RE: saito's 220 large bore carb & pump
[quote]ORIGINAL: onewasp [quote]ORIGINAL: seanychen Also an over-bored engine tends to consume more fuel than the long stroke engine of same displacement. A prime example is Saito 82 v.s. Saito 91. Saito 91 puts out more thrust than the 82 at lower fuel consumption. [/quote] seanychen Not a bad out, but tell me where the above quote refers to carb bore???? [/quote] Not here[:D] Some of us started
Posted on: 7/13/2007 11:12 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6108618

RE: saito's 220 large bore carb & pump
I think the title of this thread speaks of the bore on the carb, not the bore of the piston.
Posted on: 7/13/2007 8:00 AM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6105468

RE: saito's 220 large bore carb & pump
[quote]ORIGINAL: onewasp Sorry, but that simply isn't true. Equal displacements will not have unequal volumes and compression stays the same here as we have defined only changes in bore or stroke. Equal CID is equal CID (by definition). This applies to two and/or four strokes----makes no difference as volume is volume. BTW re-read my post---I said the STROKER would have more torque (it will). Piston speed also goes up. (and that isn't all good) [/quote] Just to clarify, I was referring to the volume of air-fuel mixture above the piston when the piston is at the Top Dead Center. The combustion volume is merely the little volume that's trapped between the cylinder head and the piston's top surface when the piston is at the Top Dead Center. This is NOT displacement. Displacement = bore * stroke. Displacement is the difference between the volume above the piston when the piston is at Top Dead Center MINUS the volume above the piston when the piston is at the Bottom Dead Center. I hope this can be understood without having to draw a picture. Two engines with same displacement but different bore area can actually have different combustion volume. If this is still not understood/accepted, it needs to be discussed in a different thread.
Posted on: 7/12/2007 10:07 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6104355

RE: saito's 220 large bore carb & pump
I am by no means an engine expert, and I wish not to hijack the Saito 220 thread to discuss the fuel economy of over-bored engines. I just know that my Saito 220 lasts longer than my Saito 180 on the same 20 oz tank. My Saito 91 lasts longer than my Saito 82 on the same 10 oz. tank. As for the propeller, I actually went to Toledo show 2 years ago to buy a Mejzlik 20x6, but it was sold out, and I bought a Biela 20x6 instead, not realizing there is that much difference between the 2 props. I don't want to spend another $50 for another 20x6. Do you think a MA Classic 20x6 is less loaded than Biela 20x6?
Posted on: 7/12/2007 9:55 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6104313

RE: saito's 220 large bore carb & pump
I find the Biela 20x6 load to be on the high side for my Saito 220. It is much more comfortable with APC 19x8W than Biela 20x6. Maybe I should try a lesser load 20x6.
Posted on: 7/11/2007 12:39 AM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6096395

RE: saito's 220 large bore carb & pump
[quote]ORIGINAL: onewasp [quote]ORIGINAL: seanychen Also an over-bored engine tends to consume more fuel than the long stroke engine of same displacement. A prime example is Saito 82 v.s. Saito 91. Saito 91 puts out more thrust than the 82 at lower fuel consumption. [/quote] I've been 'around' engines (stroked; bored;bored and stroked -- you name it) for a long time. I would love
Posted on: 7/11/2007 12:35 AM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6096382

RE: saito's 220 large bore carb & pump
Also an over-bored engine tends to consume more fuel than the long stroke engine of same displacement. A prime example is Saito 82 v.s. Saito 91. Saito 91 puts out more thrust than the 82 at lower fuel consumption.
Posted on: 7/10/2007 12:26 AM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6091631

OS 200 Surpass-FI
http://www.os-engines.co.jp/2007spring-summer/fs200sfi/index.htm Translated via Babelfish: A thread the world of the stunt where the flight which is not disordered is required. O.S. The private engine which overtakes the power quality of F3A competition is added to line-up. By the fact that development concept is squeezed in F3A competition, the character which begins the output characteristics of the engine was directed to stunt flight, all settings were administered. The electrically controlled gasoline injection system which is largest feature the finishing being something which is made to form with the cooperation development with Futaba, administers the setting which is optimum to stunt flight in all aspects of power, the response and fuel economy, in everyone of the competition flier has become the completion which satisfaction it can receive. In addition because the fuel injection type engine is made to stabilize, it pressurizes the fuel inside the pump, in order always to have controlled in fixed pressure, vis-a-vis whatever kind of attitude change which is in the midst of flying, it can obtain the output which is stabilized. Furthermore e.g., it utilizes the good quality of electronic control and of course in flight mixture adjustment of the medium speed and high speed it is possible with control from the transmitter, to do the fuel supply which is always optimum memory it is possible the highest rpm in flight, ahead the one step the function which goes is loaded. In the preciseness which is fed back to the fingertip which has the feeling where the F3A flier is sharpened securely, it probably is to be able to get wise the real value. As for EC-3 which controls the fuel gushing quantity from the injector, it is the part which can be called the brain of FS-200S-FI which everything administers the operation of the engine literally. In addition also decoder function has, exhausts the best to efficiency showing in the competition meeting e.g., the highest rpm in flight memory is done. Because the F3A flight performance which it stabilizes is actualized, O.S. FS-200 which reaches the one cylinder 4 stroke engine maximum aerodynamic volume displacement of the engine is designated as the base. In addition e.g., it changes to the existing black head, adopts the head of the blue color, O.S. Expression as a top model of the new generation 4 stroke engine was given. Because the flight where the accuracy and powerful, and fuel economy are good by squeezing the purpose of flight in stunt competition, is actualized, the fuel injection unit which has the compressed type pump was made to complete. Furthermore it evolved the merit of electronic control, it made the flight which has キレ possible. As for this engine of the private model for FIA F3A competition because of the F3A competition private model, knowledge and experience in regard to F3A competition and the engine in regard to use are necessary. ************************************************************************************************************************************************* Hopefully they got the FI system figured out this time. But the blue head reminds me of the 70 Ultimate pressurized system, which wasn't quite a hit.
Posted on: 6/19/2007 12:34 AM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=6005428

RE: What prop
MA 3-blade props get pretty good RPM for their advertised size. However, I find that the pitch flattens. My plane with 14x7 3-blade @ 9500 rpm flies at below 50 mph top speed. Theoretically it should be close to 65 mph. MA plastic props flatten pitch at the tips, which will increase rpm, but not necessarily performance.
Posted on: 6/14/2007 9:55 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5989125

RE: Prop size vs Torque
[quote]ORIGINAL: tstotts Any of you guys know how to figure load factor on 3 bladed props? [/quote] Going from 2-blade to 3-blade requires 10% reduction of diameter to stay in the same rpm, assuming pitch, chord width and profile stays the same. Sometimes, chord width will be narrower (e.g. Master Airscrew & APC 3-bladers), in which case you won't have to lose all 10% in diameter. In order to have an apple-to-apple comparison, you should experiment with Graupner. Their 2-blader and 3-blader use the same piece. So Graupner's 12.5x7 three-blade should swing the same rpm as their 14x7 two-blade.
Posted on: 4/30/2007 9:44 PM by Author "seanychen" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=5794198

RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?
I think we should wait for his flight report before eagerly recommending expenditures, an imminent one however.
Posted on: 4/30/2007 9:31 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5794109

RE: Just a matter of time. ARFs getting real cheap
[quote]ORIGINAL: stangevil29 Any guess on who the makes those planes? Are they a copy of someone elses product? I see the wings on that ultimate are already glued together. I'm might have to look into it a bit more. I like to beef up my bipes, escpecially since they call for a 1.40 Fc and they sell it with 26cc gasser as a combo. What the heck, well see what happens. Stangevil29 [/quote] You don't mean World Models, do you?
Posted on: 4/29/2007 10:40 PM by Author "seanychen" in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=5789502

RE: Just a matter of time. ARFs getting real cheap
Thanks the Brits for what they made Hong Kong into: hub of ARF trades!
Posted on: 4/29/2007 10:38 PM by Author "seanychen" in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=5789486

RE: Prop size vs Torque
Right thrust will help offset the left yaw during upward pitch. However, when you do an inverter pull-up (downward pitch), you will need left thrust. Counter-rotating prop is perfect in theory, but hard to implement, especially if you want to keep both thrust the same. I've found that when I increase prop pitch, the P-factor increases. Talking extremes, when I switch from 16x6 to 16x4W, the left yaw during up pitch pretty much went away. I can guarantee you that when you put your 12.5x11 3 blade on, the left veer during upline will be worse. Give that a try. If that's true, you know what to do then.
Posted on: 4/29/2007 10:35 PM by Author "seanychen" in the forum "Aerodynamics"
http://www.rcuniverse.com/forum/fb.asp?m=5789466

RE: best 3D ARF under 400$
Extreme Flight Yak 74" http://www.extremeflightrc.com/html/74yak54.html QQ Yak 23% http://www.somenzini.com/html/aircraft/yak73.html
Posted on: 4/29/2007 10:17 PM by Author "seanychen" in the forum "3D Flying!"
http://www.rcuniverse.com/forum/fb.asp?m=5789382

RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?
Well, I wouldn't go to the extreme of 10x8 either, as it won't have enough prop wash to accelerate the plane to a speed that will take advantage of the 8" pitch. What he really needs is a 3-bladed prop, preferably 13" diameter to look right, and to fly at good speed, 8" pitch. Graupner has a 12.5x7 3-blade prop that may look all right and fly the plane well if he has a .91 4-stroke instead of a .60. Saito 91 may just be the ticket. Hmm, I didnt' even think about the speed you lose in high G turn. I am sorry, I've been spoiled with the new generation lightweight ARF warbirds, with which I hover and torque roll. I've never been trained with a brick warbird to fly "scale". I don't know if the Kyosho Zero .40 will stall at 25~35mph, but if that's the case, he will need to land it pretty hot. Well, nice thing about prop experimentation is that they are cheap and easy to swap out. I have > 20 props in my garage as a result.
Posted on: 4/29/2007 3:57 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5787708

RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?
[quote]ORIGINAL: DaveInLA 57 mph might be "pathetic" to sport fliers, but it's certainly more than scale, and that's good enough for me. I'll try 12x6 first and see how that goes. Anyway, re: the 12.5x5 prop putting out 6.5 lbs thrust, I know that's all just theory, but wouldn't that mean that theoretically, this engine and that prop would be able to hover this plane? [/quote] This estimation is more than just theory. This is an adjusted estimation based on my other "real" thrust measurements: APC 13x4W @ 11000 rpm = 7.5 lb Anyway, if the thrust is the same as your weight, you can get to a point of hover, but you will need more to pull out. This little Zero won't hover too well even if you have 2:1 thrust to weight ratio. The key to hovering well is to maintain in hover heading, and you will need very strong pitch and yaw authority. Yaw authority is something warbirds lack. The 12x6 will be a good choice. I recommend the 12.5x5 MA Classic more because of the look, something that might matter to you. http://www.masterairscrew.com/index.asp?PageAction=VIEWPROD&ProdID=29
Posted on: 4/29/2007 1:25 AM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5785582

RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?
[quote]ORIGINAL: DaveInLA Ok, newbie question. I know what the numbers of a propeller's specs mean in a physical sense, but how do they affect flight? For example, I know that larger diameter typically means fewer revs for any given engine, but if you increase the thrust of the prop (ie, 12x6 vs. 13x5), does that make up for it? For example, how would a 12x6 prop fly with this engine compared to a 13x5? Thanks [/quote] OK Dave, this is not as straight forward as you think. Many factors affect the thrurst, including diameter, rpm, pitch, chord width, airfoil, and profile. From what I've gathered, I've found the following relation ships: Thrust is proportional to RPM^2 Thrust is proportional to Diameter^3 Thrust is proportional to Pitch^1 Thrust is proportional to Chord^1 Speed is proportional to Pitch^1 Speed is proportional to RPM^1 However, you can't have it all, since for a given engine: If you go up 1" in diameter, you need to reduce pitch by 2" to maintain the same RPM The best thing to do is to find the rpm that yields peak power, and prop to allow engine to peak at that RPM. Magnum 60 4-stroke is a good engine that's also pretty light. I think its peak power is about 10500~11000 rpm. I don't have this engine, but based on my experience with other engines in this size range, I estimate the 12.5x5 will peak at 10500. It should give about 6.5 lb. of thrust, based on the thrust measurement I've done on similar size props. The ThrustHP calculator has an error which assumes thrust to be proportional to Diameter^4, but does not account for pitch. chord, or profile. The only thing the ThrustHP does correctly for is speed, which you can easily calculate by hand: 10500 rev/min x 5"/rev x ft/12" x mile/5280inch x 60min/hour = 49.7159 mile/hour, about 50 MPH. If you want the airspeed to be faster, figure out what MPH you want, and back calculate the RPM and pitch you need. Based on the RPM and pitch required, estimate what diameter you need to drop to to achieve the RPM.
Posted on: 4/28/2007 2:50 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5783207

RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?
Master Airscrew Classic 12.5x5. It will be the right load for the engine @ 10500 rpm, looks great, and fly scale speed at about 50 mph. For your Zero, you want the prop diameter to be large enough to extend past the cowl and blast enough air. Richard L has the same airplane with YS 63 w/ Graupner 12x7 @ 12000 rpm, and it flies so fast it's hard to imagine it's a real airplane.
Posted on: 4/28/2007 2:31 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5783162

RE: Finished my Dave Patrick Ultimate!! update - maidened with video
My Ultimate setup: For rudder I add the double bevel on the fin side, so max deflection will almost touch the elevator For elevator I also double beveled, resulting in 60 deg of deflection in both directions For aileron, I didn't double bevel, but I maxed out the physical movement possible Low rates are 50% of the full rate. CG is at the aft end of the recommended range. It's hard to achieve this aft CG because plane is inherently nose heavy. I had to put the battery pack at the tail, remove the cowl, and use wood prop to get there.
Posted on: 4/25/2007 10:49 PM by Author "seanychen" in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=5771130

RE: AX Engines
You shouldn't have to worry about an engine not lasting 10 gallons for your RV-4. Most RV-4s don't get that much flight time anyway. It's a sport plane, fly around type of plane. People who own RV4 usually don't fly it as much after a few year or so. 1 gallon of fuel will provide 12~16 flights, which should last a month if you fly on the weekend, 4 flights per weekend. Assuming you fly nothing else throughtout the year, you might hit the 10 gallon mark after a year. I would actually recommend Thunder Tiger Pro 46, the undisputed champion of .46 2-stroke engine in terms of reliability. I have one. Even after getting run over by a car (I'm serious), the engine still runs like a champ, swinging MA 9x6 @ 17000 rpm or APC 12x4 @ 14000 rpm. This is an OS in its former glory before things went south in some of OS products.
Posted on: 4/24/2007 10:16 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5765654

RE: 120 AX with afermarket pitts and 3d prop reccommendation
Start with APC 17x6 for 3D prop. I don't know what the Bisson Pitts would do, but they usually result in power loss for smaller OS 2-strokes. On the larger 160 FX, the power between stock muffler and Bisson Pitts favors Bisson Pitts. Hopefully for the 120 AX you get even performance. As for pressure loss, Bisson Pitts always result in less pressure than OS's stock muffler.
Posted on: 4/24/2007 9:36 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5765444

RE: Equal to Saito 100
If you want to swing the same prop at the same rpm as Saito 100, try Super Tigre G90. It's a little weaker than OS/Magnum 91 2-stroke.
Posted on: 4/24/2007 9:29 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5765387

RE: Saito 100-125
It would be kind of difficult to slip 3.8 oz of slug into a Saito 100 without getting detected. So I think the weight check is safe. On the other hand, I would love to have a real 125 that weighs 20.9 oz.[:D]
Posted on: 4/24/2007 9:26 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5765366

RE: Saito 82 muffler vibrates loose. Is there a fix?
Some Saito mufflers will still come off even with Tefflon tape. I just go double portion, going twice around.
Posted on: 4/24/2007 9:19 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5765321

RE: Magnum .91XLS or .91 RFS w/APC 14-6 to 15-6's
Hello, for the RV4, depends if you want sound or speed. Frankly, if you use a Pitts muffler and swing a 15" prop, the 2-stroke and 4-stroke .91 power end up being about the same. My Magnum 91 4-stroke swings 15x4W @ 9800 rpm. My Magnum 91 2-stroke swings the same 15x4W @ 10500 rpm using stock muffler, but drop down to 10000 rpm with scale muffler. Furthermore, you can boost 4-stroke power by using high nitro. So for the RV, I think the 4-stroke should work out better for you. By the way, these are also the same price after discount if you know how to do it.
Posted on: 3/17/2007 9:36 PM by Author "seanychen" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=5577034