Register

If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Page 13 of 14 FirstFirst ... 311121314 LastLast
Results 301 to 325 of 327

  1. #301
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    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.. . 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.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  2. #302
    combatpigg's Avatar
    Join Date
    Nov 2003
    Location
    arlington, WA
    Posts
    17,709
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    That's a great report MJD..!
    After such a long lay-off that is a pretty hard core way to get back into flying.
    I've been too busy building up my ranch operation and building a hot rod car to do any RC.
    I'll use my Jett .46 powered Demon to get back into the flow and to get the eyeballs used to tracking a little black dot out there.
    Glad to hear you like the mixture control so much. It would be good to have that on a switch that has end point adjustment?
    Pitting with a cowl on...I use color coded silicone lines, T fittings, hunks of aluminum rod to plug off lines and "hemostats" to pinch off the line to the engine and to fish the tangle of lines out from inside the cowl. Just a rough sketch of how / what I do. Cram the whole mess back into the cowl, then fly. With as much pressure as we are working with you can have lots of slack in the plumbing.
    I also pit with the glow plug removed and spin the engine before popping in a fresh plug to make sure the crankcase is clear after the last flight.
    WHO GUNNA FEED MAW KEEEIDS..???

  3. #303
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    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..



    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  4. #304
    combatpigg's Avatar
    Join Date
    Nov 2003
    Location
    arlington, WA
    Posts
    17,709
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    Those 8x10 props ought to be pretty tough..!
    If it sounded good going past you I'll bet you get some impressive MPH figures.
    The helmet cam is easily the best way to go I think. I'm using an older camera that weighs a ton..but at least it works.
    Are you launching this sucker yourself..?
    WHO GUNNA FEED MAW KEEEIDS..???

  5. #305
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    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.

    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  6. #306
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    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.

    SD .65 video
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  7. #307
    iron eagel's Avatar
    Join Date
    Jul 2004
    Location
    Middleboro, MA
    Posts
    3,080
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    The pass at 1.58 of the video is 167.14 mph if I did it right.

  8. #308
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    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.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  9. #309
    iron eagel's Avatar
    Join Date
    Jul 2004
    Location
    Middleboro, MA
    Posts
    3,080
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    The last pass seemed faster but I couldn't get any good lines, and I'm not sure I did it right either so don't get to worried about it.

  10. #310
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    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.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  11. #311
    smoknrv4's Avatar
    Join Date
    Dec 2003
    Location
    RR#7 Aylmer, ON, CANADA
    Posts
    1,165
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    All I can say is it was awesome! Nerve racking at first hand launch but it turned out alright, other than the strong taste of nitro. LoL
    Impressive sounding engine though, ear drum pounding for sure!
    HOW AM I SUPPOSED TO FOLLOW THAT WITH THE CAMERA !!!
    RB#239 Elgin Flyers, St. Thomas, Ontario

  12. #312
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    It was your mighty hand launches that saved the day. If I could avoid panic and lay off the sticks for a couple of seconds..

    Just for you, I'm going to drop in another head shim and switch to 30% fuel. Your eyes weren't watering nearly enough.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  13. #313
    iron eagel's Avatar
    Join Date
    Jul 2004
    Location
    Middleboro, MA
    Posts
    3,080
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    Well he's smokn...

    Should go nice when you dial it in. I think you will find a catapult makes launches almost a non issue, still propped for speed it an adventure still, although a bit less drama.
    I know what you mean as far as matching the prop engine and airframe, it's quite a learning experience for me.

  14. #314
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    I bought an assortment of AMA D speed props to try out. 8.2x11, 8.2x10.5, 8.5x10.5, 9x12 (older style for lower rpm and lots of nitro, my pipe will be too short for these). Lots of expensive props to snap on landing. Also finally found a European speed flier who sells props for the F3S crowd, might try a couple of those out too.

    The drag of the exposed engine, pipe, tank etc. is not a good combination with a small high pitch prop (the cylinder is nearly as tall as one prop blade), so I figure the cowl should help a fair bit.

    I recently started bungee launching my Funjet, what a difference that made! That convinced me I need a launcher.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  15. #315
    iron eagel's Avatar
    Join Date
    Jul 2004
    Location
    Middleboro, MA
    Posts
    3,080
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    Check out the second video of my Stingray I built a launcher using the idea that Speedy G came up with with using bungee that is stretched around pulley.
    http://www.youtube.com/watch?v=MmF5kgUkEgQ

    That video is a good example of a prop that almost works on a airframe. Trying to get the pull you need from a small diameter prop is interesting to say the least.
    I think of the problems with that plane is the cowl size, the cowl area behind the prop has been reduced by 40% in area that should help.
    Your right, whats behind the prop has a dramatic effect hopefully in the near future I will get to see if the repair/modification to my cowl helped...

  16. #316
    bob27s's Avatar
    Join Date
    Apr 2002
    Location
    Cleveland, OH
    Posts
    5,556
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread


    ORIGINAL: MJD

    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.

    SD .65 video
    Nice [&:][8D]
    Bob Brassell
    Jett Engineering - Engine Mfg Support Forum Host
    rjbrassell@gmail.com or bob27s@hotmail.com
    RB-78

  17. #317
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    I managed to Wav-O-Scope the pass at about 1:40, and doing it a bunch of times it indicates maybe 185 or so depending how you pick the points, the trace is a bit grainy. I don't claim huge accuracy but errors in Doppler analysis also go to the low side. Gut feel from being behind the Tx is I don't disagree. Never flown anything this fast before, I know that. The Jett .50 and West .50 versions are quick when everything is happening, but not quite this fast.

    No conclusions but certainly encouraging. Better tracking will tell.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  18. #318
    iron eagel's Avatar
    Join Date
    Jul 2004
    Location
    Middleboro, MA
    Posts
    3,080
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    I can't wait to see how it does with the cowl on it and you get it all dialed in and are more comfortable with it.
    Nice plane!

  19. #319
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    I think a fresh engine with the 7-port .67 piston/liner set will put it over the magic mark.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  20. #320
    combatpigg's Avatar
    Join Date
    Nov 2003
    Location
    arlington, WA
    Posts
    17,709
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    If this engine / prop gives you 200 mph+ on a bench run..then I believe that taking some blade area out of your best prop is the 1st thing I'd try if you aren't running at 95% of what this thing should do on paper.
    WHO GUNNA FEED MAW KEEEIDS..???

  21. #321
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    All I know at this stage is what's been done in Europe by the speed junkies there. The OPS .65 is known to have 210-215 speed capability in a clean airframe, but how the Demon's drag properties qualify in relative terms I really don't know. I have a hard time imagining the combination is not capable of 200, I have hopes more than that. I wonder how much effect the cowling will have, that's a big-ass cylinder sticking up in the airstream at the moment. Time will tell, there's 6-8 weeks of flying weather left.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  22. #322
    smoknrv4's Avatar
    Join Date
    Dec 2003
    Location
    RR#7 Aylmer, ON, CANADA
    Posts
    1,165
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    Can't wait to see her fly again! I'm hoping to head up your way again this coming weekend to do some more pylons, you going to be there?
    HOW AM I SUPPOSED TO FOLLOW THAT WITH THE CAMERA !!!
    RB#239 Elgin Flyers, St. Thomas, Ontario

  23. #323
    MJD's Avatar
    Join Date
    May 2003
    Location
    Orangeville, ON, CANADA
    Posts
    6,637
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    Could be. Wish I could build a launcher by then.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  24. #324
    smoknrv4's Avatar
    Join Date
    Dec 2003
    Location
    RR#7 Aylmer, ON, CANADA
    Posts
    1,165
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    I don't mind launching, what about a cheap and dirty dolly with nose wheel steering. Just have the rudder ch hooked up to the servo on the dolly and when the SD leaves it just unplugs from the dolly.
    HOW AM I SUPPOSED TO FOLLOW THAT WITH THE CAMERA !!!
    RB#239 Elgin Flyers, St. Thomas, Ontario

  25. #325
    iron eagel's Avatar
    Join Date
    Jul 2004
    Location
    Middleboro, MA
    Posts
    3,080
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: Screamin Demon .65 build thread

    Several guys at my club have tried dolly's like that with varying degrees of success.
    Getting a reliable connection to the rudder channel which will disconnect easily is one issue, and getting enough thrust to obtain flight speed (with high pitch props) is another. That is what made me decide to go with a catapult style launch despite the work it took to build one.

    I'll post better pictures of my SRB (Stretched Rubber Booster) not solid rocket booster later today. Speedy-Gonzales designed and posted pictures of his launcher for speed planes and it is a simple elegant and reliable setup for launching. Where I am not using glow motors for my speed planes at this time I do not have the detention setup that he used installed on mine yet. His releases the plane just as the launcher is at maximum velocity and if I recall his launcher will handle airplanes up to 6 pounds or better using two bungees looped around pulleys on either side, mine uses two bungees internally under the support sled as the main boost mechanism (providing 40 lbs of thrust) and two external bungees which supply force for the initial acceleration and they can be added to if need be for a higher terminal velocity or launch load.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Da83580.jpg 
Views:	7 
Size:	99.5 KB 
ID:	1804120  


Page 13 of 14 FirstFirst ... 311121314 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -6. The time now is 02:18 AM.

SEO by vBSEO 3.6.1 ©2011, Crawlability, Inc.