RE: Screamin Demon w/West 50V1 with tuned pipe question
[quote]ORIGINAL: kirkster2003 I think so. I can't see down thru it. Funny thing is, it sure is loud when I run it! [/quote] The supplied pipe is "silenced" but that is a relative term, it still makes lots of noise. Not as harsh as an open pipe mind you. I have yet to build one with the standard center fins so have never had to deal with the interference problem with side exhaust and tuned pipe. My West .50 version has tip fins. They are more of a PITA to install but no big deal if you can build kits. Did you put in some kind of hard point for the pipe standoff? Get that engine singing on the right prop and you have a 170mph machine, maybe more but proof is in the radar gun. It will outrun a Magnum R on the same power package. Similar power to a Sport Jett .50 but needs less shaft load as it is timed a bit higher. Very nice engine IMHO, easy to handle. As per my PM, APC sport 9-6 is a great test flight prop - lets the engine spin in happyland, more pull from launch and top speed governed by the pitch/dia combination.
Posted on: 9/18/2012 11:33 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11232582

RE: Screamin Demon .65 build thread
I'm not worried. That pass might have been just what you said. I was tweaking needle settings, who knows if the prop is working well with the airframe, the engine and pipe etc is all out in the breeze, etc. All that really matters on these two flights is that it flies [8D]. Once I am comfortable with it and I get it fully cowled, then it's time to turn the engine into a fresh .67.
Posted on: 9/18/2012 8:07 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11232337

RE: Screamin Demon .65 build thread
All the passes in the video are a long way from the camera (as in 200' plus), so they're hard to analyze and the Doppler shift will read low due to the angular error. So I don't think anything too conclusive will come, but it was moving along alright.
Posted on: 9/18/2012 7:10 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11232280

RE: Screamin Demon .65 build thread
IPhone video.. okay you can't see much but you can get a crude sense of the speed. I did not dare fly close to the pits on this second flight, it was a bit touchy in pitch due to CG and throws needed sorting out. But proof it flies at least! We'll see if a rough Doppler can be had from the audio track. [link=http://www.youtube.com/watch?v=XG4lgIXIOz0&feature=player_embedded]SD .65 video[/link]
Posted on: 9/17/2012 4:35 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11231620

RE: Motor question for RC glider
If you are stuck you can simply cap a booster "-0" motor with 1/8" or so of epoxy, that will prevent the burn-through (which is fairly violent as the motor is at operating pressure when it pops, and it burns things too of course) from doing anything. Same is true for a regular motor with delay and ejection, but you need to scrape out the clay and granular blackpowder first, to get down to the pressed delay composition (grey color). At 1-1/2 pounds you'll need a D or E motor to make anything interesting happen.
Posted on: 9/17/2012 3:10 PM by Author "MJD" in the forum "Model Rockets & Rocketry"
http://www.rcuniverse.com/forum/fb.asp?m=11231524

RE: Screamin Demon .65 build thread
I wouldn't dare launch it myself at that weight and with the piddly static thrust. SmokinRV4 did the honors. Besides, that way I don't get the tuned pipe blasting into my face or chest. I still want a catapult, I hate the first two seconds of wondering if it will mush in or torque roll. As the years march on I get more and more conservative.. most likely due to dwindling reflexes.
Posted on: 9/17/2012 3:02 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11231516

Jett .90 carb / OPS .65
Just a quick note of support - I finally actually flew my OPS Speed .65 with the Jett .90 carb Dub machined to fit for me. Already bench run a few times. This combination works flawlessly, the engine throttles as well as you could hope for and idle is reliable, transition quick. Very troublefree setup. Gobs of top end. And since the cost of carb and machining was very reasonable, I know what I will be doing when time comes to retrofit a couple of other engines waiting in the wings.
Posted on: 9/17/2012 10:48 AM by Author "MJD" in the forum "Jett Engineering Support"
http://www.rcuniverse.com/forum/fb.asp?m=11231243

RE: Screamin Demon .65 build thread
Yeah, they call that baptism by fire I think.. [X(] I have been flying "brisk" electric models but only in the 120-125 range, in fact I warmed up prior to the Demon maiden with a 950W Funjet. Big sky at the field helps, my sport flying is in tight confines. In truth the highest stress part of these flights is the hand launch. Predictably, I have not yet built a Demon-catapult but that would make things so much simpler. (and I wouldn't have to drag every last rpm out of the engine for launch) What astounded me is that I never broke the prop in two landings and three launches.. 2nd launch went "Uh oh, too much backstick, torque roll - ZOT!". Thank goodness for tall grass and soft dirt. If the engine was fresher the risk of stopping at TDC at the end of the flight would be higher and that is generally what costs props in my experience. At $16 a pop that can hurt after a while. The West .50 I had on my other Demon was famous for doing that, but it was hit or miss so setting the prop differently didn't help. I made the cowl so snug that the plumbing is a challenge esp with the addition of the mixture control valve. As it stands, I have to cut the tie-wraps on the pipe, remove the pipe and take off the cowl (4 screws) to get at anything. That will get old real quick. I can make it better with just a bit of effort. Needs a bit more exit area and I should put some epoxy filler on the inlet and get a bit of a radius happening I think. A hemostat is a must to stop siphoning into the carb with everything in line as it is with a rear rotor engine. It has end point settings on the IMC channel. I have it on a potentiometer dial above the throttle stick, and it goes from too rich to peaked on the ground over the full travel. This took some fiddling, as the IMC takes only a small amount of travel to have a noticeable effect on mixture. I use an HS85MG and wire pushrod, servo is siliconed down, so far works like a champ through the ground test runs and these two flights. At the end of the day the plug was still alive but the element was a bit distorted, I probably had it a bit too lean in the air at some point or I need to spend less time peaked at hand launch. Again, two 2 minute flights, with an aft CG and oversensitive control settings had me busy, so I still need practice on IMC management. One plug a day is acceptable for this type of flying. The 3.2 ounce Ceconite covering is tough as nails (this is certified light aircraft grade). A bit heavy for sport use but it sure stiffened up this airframe and it takes a pretty good poke to puncture it. I imagine if I stuff it the airframe will implode like a television tube because of the shrinkage pressure from the covering. It looks really cool doing show passes at full tilt. Still waiting for Iphone footage, I hope one or two passes show up at least. If there is anything visible I'll upload it to YouTube and post the link here. Time for the helmetcam I think. Proof of the pudding is doing it again. I was fully prepared to take home a bag of rubble, but it turned out alright. I hate to guess at airspeed, but it was moving. I doubt it is an F3S contender but certainly good for some laughs. If I can get over 200 and document it on video I'll be a happy camper. As I recall 202 is the target..
Posted on: 9/17/2012 9:38 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11231160

RE: Screamin Demon .65 build thread
Can you believe it.. it finally flew today! The local RC club was having a pylon practice day, smokinRV4 was going so the decision was made - scrape off the dust, shake off the willies and fly the darn thing. And fly it does. I still never got the plumbing completely sorted out with the cowl on (a couple of hours of focus at the bench would fix that) so decided to fly it naked. First hand launch went okay, but my control throws were wayyyy too high not to mention CG a bit too far back. After puckering up and getting it to altitude, got it sorted out, nearly trimmed out on the maiden, and stayed high for the entire flight. In-flight mixture control rocks, I'm a convert now. I was able to peak it for hand-launch then richen up as it climbed out, with a CL speed prop static thrust is not great so all the rpm it could muster was helpful. It is about 4-1/4 pounds so I was concerned about landing, but no sweat, it flared out fine and slid gently to stop on the grass. As to high speed flight, we have no idea how fast it was going, but was it fast? Uh, yeah, it was pretty fast! Used an Eliminator 8.25x10 prop for these flights, experimenting will come later. I'm running a couple of extra head shims, and 15% syn/cas sport fuel with castor added to bring oil up to about 23%. Ground rpm is north of 21k. After getting a bit more relaxed on flight 2, and getting the trim nearly neutral (I was a bit busy both flights so this took some effort), I was able to line it up and make a few high speed passes. With the mixture sounding about right it wound out big time for 3-4 passes and it is faster than any Demon I have flown to date. Someone took some Iphone video, we'll see if that comes out clear enough to post, and if the audio is good enough to get a rough Doppler read on it. All in all I was far more nervous than I needed to be, it seems to be a success and more flights will prove what it can and cannot do. Has a 10.5 ounce Tettra tank and that gives enough flight time esp. with use of the throttle (fuel draw is 4oz/minute at full bore). Sure is loud with the open pipe.. [:D]. It looks much more cool with the cowl on so I need to get that dealt with and fly it proper-like. If it survives a handful more flights I will freshen up the engine with a new 7-port .67 P/L set - as it is it has a fair bit of run time on it and nearly no pinch left ( I got it used). So a new P/L set ought to breath some new life back into it. It's not exactly a slouch right now, but there is more top end to be had. Last but not least was smokinRV4's flight with his Sport Jett .46 powered Demon. Nice and light, it goes like stink. He was using TF wooden pylon props today, and I think that is what saved the aircraft... after two very, very low full bore passes, a certain infamous veteran of the Canadian pylon racing circuit was heard to egg him on -"how low can it go?". We promptly found out on the next pass when he performed a full throttle touch-and-go. As you can imagine, with no landing gear this is not recommended. The aircraft crunched into the ground, looked like it might cartwheel and disintegrate but instead bounced up again, recovered, and glided neatly to a landing off the end of the runway in the adjoining field, engine still running but throttled back as it was evident that it was not actually pulling on the airframe anymore when revved up. Not surprising as both blades had been sheared off nearly to the hub! Had it had an APC prop or anything less frangible I think the outcome would have been disaster. The aircraft is A-okay except for a weed puncture in the covering that should take all of 10 minutes to fix. Amazing it survived, but J is pretty quick on the sticks.. [8D] For those that have been wondering where I have been for the last year or so.. new job sucking all my time, energy and ambition, but it is getting more back to normal these days and I am starting to get back at things that have sat dormant for ages. For two years my RC flying has been nearly all parkies out back for a few minutes here and there. Demon kit production ground to a halt, people were writing me and wondering what was up and I am sure I owe some folks an apology. My game plan is to make another run of kits very soon, as in this fall sometime, and when they are ready to ship (not before) I will make an announcement to that effect. But I sure let them slide for a while.. what can I say? It is painfully evident I need to come up with an electric version of both the standard Demon and especially the smaller 26" version. Speaking of which, the prototype 26" Demon flew every bit as well as I hoped, it is a nice size I think - I had a piped OPS .15 with 6x5.5 prop in mine and it was sporty, I estimate 100-100mph on the on the top end. The other prototype flew on an OS .25 VF-DF and hauled butt until a figure 9 rekitted it (way to go J). I think this size is perfect for a 400-1000W electric setup. Mine is past tense as well - on the last flight some knob in an ultralight decided to buzz the field and came up from behind at very low altitude. Not wanting to hit a man-carrying aircraft and panicking, plus turning around to see what the heck was going on then trying to reacquire a delta at high speed resulted in the inevitable, I planted it in a soy bean field. Engine and pipe are fine, the airframe survived better than I thought it would but was still a write-off. The ultralight went overhead the pits at less than 100' then kept going. I've flown enough to know that you can spot RC activity from 1000' feet up easily, we were in the clear and I know this guy could see exactly what was happening and he still buzzed us.. pretty stupid if you ask me.
Posted on: 9/16/2012 3:47 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=11230314

RE: Goldberg 1/2 A Skylark
Nice work, it's always good to see when someone does an ace job on a 1/2A model.
Posted on: 6/22/2011 6:56 PM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10587552

RE: Evolution 60 or Jet 53
The Jett is indeed a significantly better engine.
Posted on: 6/22/2011 6:55 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10587549

RE: sick free flight
[:)] I've heard of fly streamers and strings etc, never done it myself. How cruel! (snicker..)
Posted on: 6/17/2011 6:47 AM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10578483

RE: sick free flight
between horizontal and vertical relative to the body so some tilt works better. MJD * you figure
Posted on: 6/16/2011 11:58 AM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10577319

RE: first flight good, second flight BAD.
[quote]ORIGINAL: eddieC >Does seem that way, but actually the extra nitro needs more air to burn, hence a cooler running engine (all else being equal). Heli guys recognized this early on, as do the speed guys. 30% is cubic $ tho!  [X(] [/quote] This does not make any sense at all. The higher the nitro methane content, the higher the fuel:air ratio. More liquid, less gas = much higher mass of charge into the cylinder per cycle, which more than compensates for the lower btu/lb for nitromethane.
Posted on: 6/16/2011 5:44 AM by Author "MJD" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=10576724

RE: KMD 2.5 rev. over 26K rpm.
Here's about 40k, if you can adjust your ears for the Doppler effect. http://www.youtube.com/watch?v=4vAw1CC4A3g
Posted on: 6/15/2011 1:05 PM by Author "MJD" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=10575721

RE: KMD 2.5 rev. over 26K rpm.
Hey that's my OPS .15! Forgot I posted that, cool.
Posted on: 6/15/2011 11:04 AM by Author "MJD" in the forum "Everything Diesel"
http://www.rcuniverse.com/forum/fb.asp?m=10575539

RE: Demon-Outlaw mix = SLOTH
I haven't got around yet to designing a new version of the Demon with a big central fin/rudder like that, but believe me I've had it in mind for a while and have doodled it a few times.. Cool! MJD
Posted on: 6/15/2011 10:58 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10575531

RE: Goldberg 1/2 A Skylark
But with modern light weight radio and power systems, they are almost new again. Gone are the days of 24 ounce 1/2A aircraft, or at least they should be.. [:)] Enjoy!
Posted on: 6/15/2011 10:55 AM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10575529

RE: test stand for breaking in 56Jett
? I was referring to this: "Do you think the Tetra is a good match for this [b]engine[/b]." The answer is sure, why not - as long as it fits in the airframe. The Jett 12oz is kind of short and squat. I have no idea if those Tettras will fit as I don't have a Jackal, but my point is that series of three tanks I mentioned are about 2-1/8" x 2-1/4" square so might have a better chance of fitting than the 2-5/8" diameter Jett 12 oz.
Posted on: 6/15/2011 5:50 AM by Author "MJD" in the forum "Jett Engineering Support"
http://www.rcuniverse.com/forum/fb.asp?m=10575038

RE: test stand for breaking in 56Jett
The Tettra 10oz, 11.5oz, and 14oz are all 58mm x 54mm in cross section. Brand of tank does not matter, the engine doesn't read labels.
Posted on: 6/14/2011 11:20 AM by Author "MJD" in the forum "Jett Engineering Support"
http://www.rcuniverse.com/forum/fb.asp?m=10573708

RE: sick free flight
A good horsefly would probably give one of those a run for the money.
Posted on: 6/14/2011 11:13 AM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10573699

RE: Liquor and F2D - perfect combo!
He needs a swivelling bar stool.
Posted on: 6/14/2011 7:50 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10573358

RE: sick free flight
Deerfly are the biggest PITA, they never give up. Horseflies hurt when they bite, but you get a lot of warning.. they're big, heavy and stupid and feel like an indoor helicopter landing on your leg, and much easier to slap than deerfly. The blackflies have been out for a bit now, hate them too. Don't like mosquitoes much come to think of it either. But horseflies are welcome for the side benefit of being excellent powerplants.
Posted on: 6/13/2011 8:36 PM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10572633

Liquor and F2D - perfect combo!
How extreme rotational speed? Check out these lunatics. "Shorter, shorter!!" http://www.youtube.com/watch?v=Lq7MJ-DL3d0&NR=1
Posted on: 6/13/2011 8:31 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10572619

RE: sick free flight
..), but it needs the power of a horsefly. MJD Aha! YouTube to the rescue: [link=http://www.youtube.com/watch?v
Posted on: 6/13/2011 8:15 PM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10572580

RE: Imangine a 1/2A size Shrike with THIS engine
I'll bet it does! [:D]
Posted on: 6/13/2011 2:44 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10571945

RE: My first speed plane attempt now with video
The throws on a Demon likely have little to do with your aircraft's needs, but for reference my low rate gives me maybe 1/8" elevator at full stick and is more than enough for high speed passes and circuits. Not enough for launches or landings of course.
Posted on: 6/13/2011 2:42 PM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10571940

RE: My first speed plane attempt now with video
One of my Demons was notorious for launching exactly as you see in the video. It improved when I kicked the thrustline a bit to the right - it was close to zero but visibly a tiny hair left, and I mean <= 1 degree. The tendency is still somewhat there, but launching banked a bit to the right helps a lot, as does launching a couple of degrees to the right of the wind. Universal non-fuselage-equipped delta problem = hand launching with any kind of airspeed. A good delta launcher is the product of a tough physical workout regimen: toss a stack of 10-12 sheets of 4'x8' 1/2" plywood onto an 8 foot high shelf one at a time while your buddy sprays hot WD40 at your face (for glow power only, electric can skip this part). 3 sets of 10 daily until you can fire a delta 25 feet in the air at 45 degrees elevation.
Posted on: 6/13/2011 11:05 AM by Author "MJD" in the forum "Extreme Speed Prop Planes"
http://www.rcuniverse.com/forum/fb.asp?m=10571572

RE: GMS Engine Tuning Problem
[quote]ORIGINAL: dhempy Can more pressure be generated by tapping the back plate? Seems to me that in years past engines were tapped at the back plate for pressurizing tanks ... just a thought. Seems that there is a raised area in the center of the back plate that looks like it was made to be tapped. I haven't had a chance to get the engine mounted on the stand yet .. I did tighten the head down though ... a bit over 1/2 turn per screw! Dan [/quote] You can't pressurize the tank directly like that with an RC carb. You can use that pressure tap to drive a regulated pump. You can use backplate pressure with a venturi, but with a carb it blows the mixture all to heck anywhere below full tilt.
Posted on: 6/10/2011 1:54 PM by Author "MJD" in the forum "Glow Engines"
http://www.rcuniverse.com/forum/fb.asp?m=10567053

RE: Where does one obtain Cox fuel in Canada?
I live 1hr north of Toronto so that's where I buy stuff. I buy Omega 25%, which as I understand is 17% total oil of a 30/70 castor/synth mix, and add enough SIG castor to bring total oil to 23%. If I am correct on the baseline oil content, the end mix is 11.1% castor, 11.9% synthetic. I'm happy with that.
Posted on: 6/10/2011 9:35 AM by Author "MJD" in the forum ""1/2 A" & "1/8 A" airplanes"
http://www.rcuniverse.com/forum/fb.asp?m=10566617