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Firefly-YCTTSFM

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Everything posted by Firefly-YCTTSFM

  1. Just came across an article in AvWeek (Nov 30, 09 issue) that said the latest Lycoming IO-390 engine variant was now certified. It's described as a replacement of the IO-360 series, specifically on older Mooney aircraft. I hadn't heard of this engine before. Quick internet results say that a new one runs roughly $33,000.00, 210 HP, 308 lb dry weight. Roughly 10% higher fuel burn than a IO-360, 7-28 lbs heaver, but 10-30 more HP. At first glance it would seem like a way to get more HP into a Cozy without going the rotary, diesel, or 6-cylinder routes. Just out of curiousity, has anyone looked at these?
  2. ... Yes, I didn't mean to imply anything negative for this particular idea... like I said I hope it works out.
  3. I tend to agree with Marc: it's sounds really interesting, but without data it's not worth the electrons we're posting with. And engineering "data" are more than numbers: it's good procedures, objective measurements, repeatable results, etc. I'm all for innovation and hope it works out, but then again I'm the type that'll listen to a sales pitch and suddenly start to realise it's a little far-fetched/too good to be true... then listen some more and realize there must be a catch ... listen some more and the BS alarm starts going off ... and keep listening to wild claims and nodding my head long after I've decided not to spend money on it simply because I know that there's going to be an absolutely spectacular train-wreck of a gotcha and want to hear it first hand.
  4. Waiter, if you don't mind me asking, how did you maintain currency during the 4 1/2 years of the rebuild? Also, did you do any specific proficency "warm-up" to prepare for flight test (borrow a RV-8 for a few hours?). PS everybody: I've already heard the "you'll save lots of currency not flying" joke...
  5. Spooky... I just picked up a Rutan book at the library, came across the Catbird and got online to find out more about it...
  6. I'll hit the softball, so others can do the hard part: "It'll vary from plane to plane based on empty CG, ballast, fuel, and other payload." My opinion: posts here imply that O-320 EZ's tend to be near the aft-end of the CG limit and often require ballast in the nose. Based on numbers from my terribly out of date manual, I would think the limiting factor to the heavy pilot would be the gross weight (or the fuselage width), not the CG. Lighter pilots on the other hand might need a lot of ballast. Caveat: the weight & CG limits for first flight are much tighter. I can see where a heavy pilot in a lop-sided airplane can run into trouble trying to make first flight. But do the math and see what you get.
  7. Wow... I'd have *never* thought that 2 inches would've made such a difference. I can understand the cowling / prop spacing being important, but it's not like you had a particularly ugly trailing edge. Thanks for the info!
  8. Waiter, when you're not busy (ha!) could you post a pic of that?
  9. If you're ever near central Illinois, I highly recommend stopping by Marshall County Airport (C75) in Lacon, IL. Their annual Father's Day breakfast is coming up and makes a nice change of pace if you're sick of hundred dollar hamburgers. Sunday, June 21, 7:00 am - 12:00 pm Pancake - Waffle - Sausage Breakfast Donations: Adults $5.00 Children $3.00 Under 6 Free Static displays Free Aviation Safety Seminar, Monday 7:00 pm Bring your own tie-downs.
  10. then we're all in the forum for the wrong kind of airplane...
  11. Anybody know the pair of canards flying over Troy, IL (NE of St. Louis) @ 5:00 pm today? Engine noise seemed louder, and kind of distinctive. Rotary maybe? I ask because 1) It's the first time I've seen one (let alone two) in flight 2) I got to point it out to my kids, who thought they looked neat 3) My wife, who's been lukewarm to the whole home-built idea, commented on how fast they were. Anyway, thanks for the experience.
  12. I have never built an aircraft or even sat in a LongEZ... (fellow n00b disclaimer). I briefly thought about this also (then after guidance from the more experienced posters, did more research & ran screaming from the idea). http://canardzone.com/forum/showthread.php?t=4493 Canard designs are very sensitive to cg and aerodynamic center changes (more so than conventional aircraft). If the changes to static balance don't scare you, try looking at the dynamic effects. The current design has known characteristics on a good range of weight/CG. You need to evaluate whether it's worth a few inches to risk (at least) sacrificing some of that range. Extra baggage room / legroom may not do much if you can't carry both fuel and passengers... or need to shift ballast around ... or effect the handling qualities of the aircraft. That's real aero-engineering stuff and for me involved more effort/risk than was remotely worth it. I suggest that if you have to ask this question, you need more research before you make the decision. 1) By shifting the cg forward you put more load on the nose gear. Questions you need to ask are: Can it structurally handle it? Do you have enough canard lift to rotate the nose on takeoff? Answer the previous 2 questions for the entire range of weight/CG. 2) How will you change the structure to support the main landing gear? How will this affect the CG? I disliked the "grazing" aspect of this aircraft when I first looked at it, but like most things on the aircraft, I've since come to appreciate the simplicity.
  13. I think I just found my new catchphrase Wonder how many times I can fit that into conversation tomorrow at work?
  14. End of pg 13 - missing the last part of the sentence "However, because of possible prop damage, avoid gravel or fields with loose rocks." Looks very nice, it's great to have one that you can do text searches on.
  15. Just as a general point, correlation does not *necessarily* mean causation. You can see trends in statistics, but rarely the whole story. My favorite: a chart "proving" that a lack of pirates cause global warming. http://www.venganza.org/about/open-letter/
  16. I think there's something to be said for sample size also. How many thousands of hours does the Cessna fleet fly in a week, vs. even the most popular home build. The Concorde had a phenomenal safety record ... until one day 5% of them were destroyed in fatal crashes. Would NASA have gotten funding for the shuttle if they knew there would on average be a fatality every 10 flights or so? Marc's comment on speed rings true to me also. I seem to recall once seeing a chart of single engine GA aircraft types: accident rates vs. approach or touchdown speeds and there being a definite correlation. Don't recall the details (you can "prove" anything you want with the right chart), but it left an impression on me. Consider also: brand new Cessna and LongEZ fly the same 400 mile trip and crash on landing. The Cessna's accident rate is 1 out of 4+ hours or so, the EZ's is 1 out of 3. Per flight hour, the Cessna is more safe, but the end result is the same. And to be fair: Cessna / overall GA numbers also include flight instruction accident rates, while experimental home-builts do not.
  17. Yes, especially since the link I posted is the *original* POH dated May 1980 (with the note that it's obsolete unless updated by newsletter #25). I like to review it for familiarization since I don't have plans yet, but I wouldn't recommend relying on it without the updates. Sorry for the quick (incomplete) response.
  18. A PDF is available at http://www.ezarc.org/downloads/longez_poh.pdf
  19. Ahh! You are correct, I had completely forgotten that. Well, that certainly simplifies things then: no reason to worry about changing the stall angle of the canard. Scrap my last 5 posts. Sorry Marc (and all), I didn't mean to labor the point, I was trying to figure out if I could change the stall angle of the canard. I wasn't trying to balance the forces & moments yet.
  20. Let me try again with pictures (increased the incidence angle for better visuals): First drawing shows canard & wing at 0 incidence and 30 AOA. Second shows the aircraft pitched at the same attitude, but with -10 deg incidence on the canard. The AOA the canard sees is reduced by 10 degrees, so the canard will no longer stall before the wing. Yeah... like I said you have to 1) prevent the canard from stalling at the same angle to take advantage of the increased stall AOA of the wing, and 2) Have enough pitch/lift from the canard to balance the wing. They seem to be mutually exclusive... but I'm not sure jettisoning the engine is the answer. A fore-and-aft sliding or variable sweep canard? Uh, this is a lot of work to save a couple of knots on landing speed.
  21. Typo: should be "... until the wing sees *32* degrees..."
  22. Marc, Oh, I follow you on the free body diagram (I've got a BS/MS in AE, but I've never used it directly to make a living). It seems to me that we need to increase the stall angle of the canard (what I was saying) while at the same time increasing the lift of the canard (what I believe you were saying). Tricky, no wonder they went with a sweeping canard on the Starship. I agree it doesn't change the stall AOA of the airfoil itself, but does in relation to the wing. Follow me for a second: Say a canard airfoil stalls at 30 deg at 0 incidence. The wing at 0 incidence stalls at 32 deg (you're safe, the canard stalls before the wing). Lower the canard incidence by 5 degrees. Now say you actually have enough elevator authority to pitch until the wing "sees" 35 degrees, the canard sees: (32 - 5 = 27). Wing stalls before canard: screwed! So I think the incidence angle *does* change the stall condition of the canard. (Note: ignores downwash or any other coupling effects.) Which is why I mentioned lowering the incidence of the canard before: to delay canard stall until the wing gets closer to its max lift. And as I said before, I don't know if you'd have enough elevator authority to pitch up (lift of the canard) to actually reach said max lift coefficient. Of course, the elevators already act like flaps on the canard. Crap, this is a complex thing... PS ... and I hope I didn't come across as a Tomcat basher... that's the last crowd I want to incite a flame-war with
  23. I mean by dropping flaps, you increase the lift coefficient (both maximum and current), resulting in an increase in lift. My thought was that lowering the incidence angle of the canard would reduce the AOA the canard sees, allowing you to pitch the wing closer to its maximum AOA before the canard stalls. You don't need the CLmax of the canard to change, just the total angle that the canard stalls at. As to whether there would be enough elevator authority to pitch far enough....? All things being equal: a swept wing will stall before an unswept (starting at at the tips for aft swept). That's why they thought putting heavy wingsweep mechanisms on F-14's were such a great idea. But it's certainly true that I don't know how much of an effect it would be.
  24. So I think there's two separate troublespots to consider when lowering the wing flaps: 1) Changing the canard by reducing the AOA or increasing the stall angle. Otherwise you can't take advantage of the increased stall angle of the main wing (canard will still stall before the "clean wing" stall angle). This is why I suggested reducing AOA of the canard, but doing so contributes the other problem: 2) Control issues caused by a big pitch-down moment from the increase in wing lif, "negative" increase in wing pitch moment. You're right, you'd need to increase the lift of the canard in order to maintain control. So you'd have to ease in a bunch of aft-stick to compensate for the flaps? Or Vortal's suggestion of separate flap / pitch controls. Didn't know that about the Starship! Did the canard unsweep to change location of the aerodynamic center or to delay onset of stall? I would guess both, as it helps with both problems above. Interesting to scratch the surface of some of the big design decisions: makes you appreciate how hard the original designers had it.
  25. Here's my first thought: add flaps and/or slats to the main wing, mechanically coupled to a device that reduces the pitch of the canard or canard elevator. I envision two separate settings: "cruise" with flaps up and "Landing" with flaps down. Coupling the two would prevent the two surfaces from ever being in a "mixed" state (not sure how to do said coupling, pushrod?). Adding high-lift devices to the wing would increase CLmax and the stall AOA, while lowering the AOA of the canard would delay stalling the canard so you can use more of that higher CL of the wing. Of course what happens in flight when you shift to landing mode? A quick decrease in lift of the canard, increase in lift of the wing... what happens to pitching moment when you add flaps? I'll go look it up...
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