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Post by Britbrat on Jul 23, 2004 11:31:00 GMT -7
I don't know if this, or the "Warbirds" is the right place, but I have a problem landing my Blackhorse Spitfire.
It has a high stalling speed & very unforgiving stall characteristics. Additonally, it is pretty clean, so it doesn't slow down easily. Our paved runway is only 200' long with 75' of grass overrun at each end.
If I do a wheels landing it scorches through the entire runway & overrun area & flips onto its back in the uncut grass. If I try a three pointer, it invariably stalls at the point where I start to flare, despite still having a lot of speed.
There is no washout in the wing tips & I have tried reflexing the ailerons up a bit to delay tip stall -- this eased the stall characteristics somewhat, but it didn't lower the stall speed. If anything it seemed to raise it a bit, which suggests that the stall is progressing more quickly from the root, rather than the tip.
Being an ARF, it is not easy to fit speed brakes without chewing up the wings unacceptably.
I even fitted it with a 12-4 prop to help bleed off speed when the throttle is closed, but that does nothing for the high stall speed.
Any suggestions, other than only flying when there is a good wind down the runway?
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Lightning
Listener
R/C Combat flier aka.Lawn Dart king
Posts: 91
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Post by Lightning on Jul 23, 2004 15:37:21 GMT -7
Yup, trade it for a Cub, or at least something you can handle ;D ;D ;D
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Wayne
Story teller
Posts: 167
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Post by Wayne on Jul 23, 2004 16:40:24 GMT -7
I haven't heard of a Blackhorse spit... does it have flaps....sound like it needs them...
To me it sounds like the wing loading is too high..don't know if there is much you can do with it at this stage that you have not already tried.....
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Post by Britbrat on Jul 24, 2004 3:51:27 GMT -7
Keith, you're getting better & better. I can't think of a zapper in return -- just yet! ;D It doesn't have flaps. I've thought about flapperons, but that will increase the effective AOA at the tips -- not a good idea (I think) in view of the nasty stall characteristics. I've also though of shifting the C-of-G back a bit but I'm a bit leery of that because this thing, at low speeds, is about as forgiving as a mother-in-law.
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Post by jetmex on Jul 24, 2004 5:42:24 GMT -7
I think I'd definitely add flaps to this model (shouldn't be too hard), and if you have to move the cg, move it forward. Aft will only make it worse. Sounds like it might be too far aft as it is, if you're stalling out of flare.
Just out of curiousity, how much does the beast weigh?
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Wayne
Story teller
Posts: 167
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Post by Wayne on Jul 24, 2004 6:00:35 GMT -7
yes you're right, flaperons is not a good idea...reflexing the ailerons up was, too bad there was not more of a positive effect. If you are at the point of frustration, what I would suggest is make some rough and ready flaps out of lithoplate, screw them on to the bottom of the wing (they will always be down) and try that. If the spit shows any improvement, it may be worth cutting some real flaps into the wing.
Failing that, I'd be looking at getting rid of some weight, - smaller battery and fuel tank, lighter wheels , lighter prop and spinner...look at any hardwood or plywood that may be in excess of what you need, and trim it out........
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Lightning
Listener
R/C Combat flier aka.Lawn Dart king
Posts: 91
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Post by Lightning on Jul 24, 2004 7:49:35 GMT -7
:)Pat, on a serious note, (seeing as it would appear I'm temporarily ahead on the jabs ;D) I think I would start with a surface incidence and a CG check!! This thing should not behave that way. If they all check out to spec, then cutting in a pair of flaps is the best suggestion I have seen yet. My 1/12 combat Spit glides like a brick, but it does not have that nasty behaviour along with it. It doesn't stall out, more like a semi-controlled crash Good luck
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Post by Britbrat on Jul 24, 2004 11:29:30 GMT -7
Thanks for the comments. It is not very heavy -- 5 3/4 lbs without fuel, & 520 sq in wing area. The C-of-G is right on the recommended value & it tends to drop its nose when inverted, so I don't think that it is too far aft, although I will try more nose weight. It could be just a poor wing design (it is semi symetrical). The incidence seems to be correct @ zero/zero.
This thing is a "fun/sport scale" Spit & it flies very well at speed, but is a beast when it slows down. A friend lost an identical one on its maiden -- stalled in the turn onto final.
If I can scrounge the wings from the dead one, I can try installing flaps, or speed brakes on them.
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Lightning
Listener
R/C Combat flier aka.Lawn Dart king
Posts: 91
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Post by Lightning on Jul 24, 2004 12:35:15 GMT -7
Pat, if you find an extra wing to play with, I'd try to add a little wash-out too. Might help with the tip-stalling. (By wash-out, I mean reduced incidence at the tip, just in case I got it bass-ackwards).
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Post by Britbrat on Jul 25, 2004 4:55:29 GMT -7
Good idea Keith ( I know what washout is)
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Post by Britbrat on Jul 26, 2004 4:44:16 GMT -7
More Spitfire "fun". Yesterday I was flying the Spit -- ripping the butt outa the sky (this thing can really dance at high speeds) when BANG --- BWAAAAAAAAAAA!!!! The 3" spinner exploded & the bits went through the prop, reducing its 12" dia to ~ 6" in a millisecond. I was caught at the downwind end of the runway without any options except a killer downwind dead stick in the Stall Queen. To keep airspeed, I executed a diving turn onto a short downwind approach, & of course, blew right through the runway & overrun & straight toward a tree-filled ravine. There was then a very scary low altitude turn across the wind (thankfully it didn't stall) out over an an uncut field at about 900 kts, with a highway looming at the projected touchdown point, so I just dove it into the long grass & gritted my teeth. At the end of a 30 yd swath of newly mown grass, the Spit was sitting right side up with grass sticking out of every crack & joint, but no damage.
OK Blackhorse, your birds are tough, but it sure would be nice if they landed with more dignity!
I also think that we need a "Crash" posting board.
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Post by Patch on Jul 29, 2004 18:58:32 GMT -7
I went out to a medium sized local pond that only has access from one side, with the wind blowing that way of course, to test fly my seaplane (ACE Seamaster) that I haven't flown in 2 years, and just reinstalled the radio and gear. It has only had a total of about 5 flights in total. I filled in the holes that once mounted the landing gear after my maiden flight because I was never going to take the radio gear out and have to set it up again ....if I had a nickel...... Anyhow....line up for a cross wind takeoff. I pull up a bit too soon and do a little skip. Just go a bit sideways. A bit meaning enough to take off the left velcroed on float. I have about 1 second to decide to cut the power and hope I don't cartwheel, or keep full power and worry about it in about 7 minutes. I keep full power and climb out. I need lots of up elevator trim, and plenty of left rudder due to the extra drag on the right wing. I finially bring her in for landing. I keep about 1/4 throttle hoping I don't slow down enough to drop the wing and do an unplanned 180. Doesn't happen..after the 180, I take her up to 1/2 throttle to keep the wing out of the water. I get her back to shore. I,m inpressed that with all the splashing she only took a couple drops of water inside. My float of course is on the unaccessable side of the pond. I'm heading up to Haliburton to a cottage on the lake and am taking my plane. As soon as I got home, I started to make a new float. Then the wife thing happens .....I asked you to fix the bannister 6 months ago and you haven't touched it, but you can fix a plane in hours . Silly women bannisters can't fly! ;D I'm thinking it's not sex night
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Post by Britbrat on Jul 30, 2004 7:12:25 GMT -7
Well Patch, did you get lucky, or was the banister thing an unforgivable sin?
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Post by Patch on Aug 4, 2004 8:31:24 GMT -7
I think that once a wedding band goes on, EVERYTHING is an unforgivable sin. It's also when they take inventory of everything you have, or could have done wrong.
I am currently working on a theory about gold affecting the female hormones. It goes like this. Once the gold gets into the females body (sinks in shortly after the honeymoon) they lose their sex drive, complain about all the things that were "cute" before marriage, and I think in many cases, it adds a lot of extra weight to thier behind. In case there is any doubt about this theory, just look at a newly divirced women (no longer wearing the evil gold band) huge sex drive, laughs and giggles all the time, and trying to get in shape.
Any extra input from you married guys will help me in publishing my book I'm working on. NEVER GET MARRIED-----EVER!!!
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Post by Britbrat on Aug 4, 2004 18:07:22 GMT -7
I ain't touchin that one budy!!
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Lightning
Listener
R/C Combat flier aka.Lawn Dart king
Posts: 91
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Post by Lightning on Aug 4, 2004 18:10:40 GMT -7
Jeez Patch, who peed in your cornflakes this morning
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Post by Patch on Aug 4, 2004 20:51:31 GMT -7
I should have added some smileys or something to let everybody know I'm just kidding around. My wife really does support me in this hobby, and I think the guys in the hobby shop know her better than me!
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Post by Britbrat on Aug 5, 2004 4:56:21 GMT -7
If I was you, I'd watch those guys at the hobby shop!! ;D
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Post by Britbrat on Aug 5, 2004 5:03:16 GMT -7
Hey Keith -- I had another fling at a combat model. A super? mini? something? Mustang with a piped OS 25 FX (I think). Danged thing ain't got no rudder!! --an' the wheels don't come down! -- but thats OK, 'cause it glides like a uranium brick. Flyin' it is a blast, & no prob at all -- I just can't get the little blitzer near another plane!!! Is there such a thing as a combat recon class, where the object is to zoom by & then run away?
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Lightning
Listener
R/C Combat flier aka.Lawn Dart king
Posts: 91
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Post by Lightning on Aug 5, 2004 5:22:37 GMT -7
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