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My new Avenger

Old 10-14-2007, 03:41 PM
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Default My new Avenger

"Classic" I-beam. The Avenger's wing shape makes it impossible to run the I-beam out all the way to the tips with a reasonable airfoil high point, so there's about 3-4" on each side supported only by the LE and TE. Doesn't seem to be a big deal since there's not a lot of stress that far out anyway. A minor warp did creep in on the outboard tip while stretching the silk on though. I can heatgun that out.

Just under 500 square inches and ~44oz ready to fly as in the pics. For its first and only flight so far the Tigre C35 in the pics was swinging a 10x6 and it was WAY too much engine for it. At a rich 2-cycle it felt like somewhere around 80mph. A 10x4 might be the answer for that.

Of course it was grossly out of trim being a completely scratch built 1st prototype of an original design. Gotta back off on the rudder offset, fix the minor warp, and it feels like maybe lighten up on the tip weight, but I'll get the others issues sorted before fiddling that. With the rudder offset slackened up I suspect the leadouts are going to be just about right.

Even with the warp and other trim whacked, I hit a few loops and 8's and it really had the ability to pop into a turn very quick albeit awkwardly due to the wonked trim.

I'm pretty sure I can find a way to eliminate about 4-6oz if I build another one of these. The maple mounts are excessively beefy and the doublers could be slimmed down a lot, the tail and fuselage center area could be stick built and sheeted with 1/32, the ply sandwich ribs in the center could use 1/64 rather than 1/32 ply, etc, etc.

That funky looking horn apparatus on the fuselage is there to correct some of the control geometry issues associated with having the tail much higher than the wing like an Avenger does. Looks odd, but it worked OK in the air on the 1st flight.



Old 10-15-2007, 03:54 PM
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Default RE: My new Avenger

Just about the best profile I've ever seen of the Avenger. Please keep us informed of your flying adventures with the plane.

Tight lines,

Tom Perry

AMA 43388
Old 10-15-2007, 04:37 PM
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Default RE: My new Avenger

I love it.
Old 10-15-2007, 05:10 PM
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Default RE: My new Avenger

The weather in south FL has been pretty miserable lately. The day I put the one flight on it the wind was blowing about 20mph and people thought I was nuts to try and fly it that day. Today was no better.

Well, I got the warp out and adjusted the rudder back to 0 offset last night. Might put something a tad heavier than the C35 in it before the next flight too. I won't say it was unstable, but it was ummm....uncomfortably "quick" using a small EZ-Just Hot Rock handle. I think I need to obtain/build a handle with some adjustable line spacing.
Old 10-15-2007, 07:02 PM
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Default RE: My new Avenger


ORIGINAL: cutaway

The weather in south FL has been pretty miserable lately. The day I put the one flight on it the wind was blowing about 20mph and people thought I was nuts to try and fly it that day. Today was no better.

Well, I got the warp out and adjusted the rudder back to 0 offset last night. Might put something a tad heavier than the C35 in it before the next flight too. I won't say it was unstable, but it was ummm....uncomfortably "quick" using a small EZ-Just Hot Rock handle. I think I need to obtain/build a handle with some adjustable line spacing.

Or adjust the elevator rigging to reduce the throws.
Old 10-18-2007, 11:25 PM
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Default RE: My new Avenger

I put a Stallion in it for one flight today. The Stallion is about 3/4oz heavier than the ST C35 and that made quite a difference in how sensitive it was.

The problem is the Stallion .35 is quite gutless compared to the C35 or even a Fox stunt .35 and wasn't running well at all with the uniflow tank. I don't think it develops enough suction to work well with the uniflow and its needle was very sensitive - like 5 clicks from dead rich to full lean with nothing holding steady for more than a couple of seconds.

Removing the rudder offset seemed to be the right idea, that helped. I'm going back to the ST C35 for the next flight and will bolt 3/4oz weight to the nose.
Old 10-19-2007, 03:28 AM
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Default RE: My new Avenger

Cutaway,

Your tank looks like a GRW-type chicken hopper/shallow wedge strapped onto about a 1/4" foam base. Close? Depending on your airspeed/laptime, that might put the 'reference height' of the tank (thinking the direction of loads in flight) pretty far outboard. That could relate to the needling problem with the Stallion, but it does sound like that's legitimately worn down some.

Nice looking bird! Appears to have ample wing area to carry noseweight you might need. Keep the word coming, and Luck!

Old 10-19-2007, 07:10 AM
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Default RE: My new Avenger

The Stallion is almost new and ran fairly steady on the test stand while breaking it in, but that was a with conventional venting not uniflow. The C35 ran OK with the hopper and uniflow setup (yea it is a GRW).

I may wind up making a 4oz shallower ordinary wedge uniflow for it...the GRW is 6oz which is a long time on a suction .35

Last time I took a Stallion apart (30 years ago) I remember the crank having just a round hole in it for timing rather than a rectangular cutout like most engines. I would think that has to limit the amount of window available for strongly pulling air through the venturi.

I could try my ST G21 .35 too if I can find the suction venturi for it...that's a tad heavier than a C35.

The leadout rake might an issue. Even with the rudder offset eliminated I can see it wants to nose out a tad. As built, they're about as far forward as possible without having the front one exiting on the leading edge somewhere or passing through the I-beam right where it ends (not acceptable structurally). The Avenger's severe LE taper is clearly problematic for a reasonable stunt type airfoil. A Thunderbird style over/under scheme could buy me an inch forward on the rear line. I'll try it with the draggier kevlar lines too, that might be one answer, or maybe .021's rather than .018's.
Old 10-20-2007, 05:42 PM
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Default RE: My new Avenger

Really nice plane! I never really got any good at CL. I crashed & trashed so many airplanes.....I could never get past a simple inside loop. Finally gave up. I was young and broke and just couldn't afford to throw my $ away like that. Sad part is I didn't realize how repairable they were. I had heard some pretty experienced contest types repeatedly saying how once a plane was repaired it was just too heavy to be much good. I was an inexperienced teenager who took the whole thing out of context and really had no frame of reference so I was throwing away perfectly repairable planes and building new ones. Stupid, eh? Now that I am 60 years old I am trying my hand at RC and I find it easier than CL. Probably because I got a simulator and joined a good club.
Old 10-20-2007, 07:41 PM
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Default RE: My new Avenger

With a C/L plane you're never more than 60 or 70' from disaster ;->

OTOH, you get to where you're not scared of the ground eventually and every landing is "dead stick", so that's not so scary anymore either ;->

I took the Avenger out again today for one flight. Still got a tiny warp I can barely see to caress out, but it was getting closer to straight. Close enough that it wasn't chasing me around the circle or going slack inverted. I think I'm going to have to limit the throws on the elevator down to maybe 30 degrees. The ST C35 was running well on the GRW tank, and with 3/4oz of lead in the nose it was grooving fairly well with no tendency to hunt. My Magician hunts and it annoys the heck out of me, maybe its LE is too blunt?
Old 10-22-2007, 10:23 AM
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Default RE: My new Avenger


ORIGINAL: cutaway
... I think I'm going to have to limit the throws on the elevator down to maybe 30 degrees. The ST C35 was running well on the GRW tank, and with 3/4oz of lead in the nose it was grooving fairly well with no tendency to hunt.
You can move the control spacing closer together at the handle to limit your movement. Then check where you get the best response. This way, when you change them on the plane, you know where to set it. Make sure you NEVER hit the limits on the plane before the handle or you will put undue stress on the plane...especially the elevator.

My Magician hunts and it annoys the heck out of me, maybe its LE is too blunt?
More likely it's something else. Check that the balance is not too far back. CL planes balance about 25% behind the leading edge of the wing chord (forward from most RC balance). The more forward, the more stable. Next, check that the wing, stab, and engine are set parallel to the center line. Most affect is wing and stab not parallel.

Good luck.

George
Old 10-22-2007, 10:29 AM
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Default RE: My new Avenger

ORIGINAL: Black Arrow

...I could never get past a simple inside loop. Finally gave up...
With my weird sense of humor, I saw humor in that..

There are lots of folks who fly both. Sorry noone was around to help you learn to rebuild those crashed planes. Some guys repair so you could never tell that it crashed. I think for most of us, the plane gets uglier after each repair...depending on how close the next flying day is.

George
Old 10-25-2007, 01:11 PM
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Default RE: My new Avenger

The latest trimming flight has it flying straight enough to do some overhead 8's. The leadouts are definitely an issue as I suspected previously. Level tension is very stout and overhead noticibly lighter although it does stay up there. With a light hand and not over controlling it, it comes pretty close to a spec 5' radius corner. Losing 6-8oz would probably help a lot if I do another one.
Old 10-25-2007, 06:42 PM
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cutaway,

I would balance the plane so it is manageable. The elusive 5' radius is something to shoot for, but don't sacrifice handling. It was put in the pattern in 1957 and, as far as I know, has never been achieved. It has to be performed in milliseconds and still straighten out at 90 degrees.

I just noticed that in a previous thread you were going to try draggy or heavier lines to keep the nose from goind out. I would suggest going for .015x60' and adjusting something else. Make sure you have no rudder offset or engine out-thrust first.

I assume you did not make provisions for adjustable leadouts.

George

Edit: Upon rechecking your pics, I guess you could not move the leadouts forward. If you make design changes, try the wings ~1" forward.
Old 10-25-2007, 07:27 PM
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Default RE: My new Avenger

The field I'm flying on has some pretty stout weed stubs even though its cut fairly low. A new set of .015's was kinked into uselessness a couple of days ago in just two flights on my Ringmaster. The .018's seem to handle the weed stub issue much better than the thinner lines.

The CG isn't too bad now. Its snappy, but not unstable and there's no tendency to "bounce" out of a sharp turn - it'll stop pretty quick. I think some of this is due to the scale aerodynamic balancers on the elevators. Years ago I build a VooDoo with the pivots on the stabilator inset maybe 1/2" rather than on its LE and the aerodynamic balancing that provided made it fly like it had power steering.

Something with a closer line spacing than my old HotRock would make using a light touch not so necessary. I really need to buy/make a real adjustable spacing stunt handle once I get beyond the rudimentary trimming.

The wing shape is definitely a tough one for the leadouts with any airfoil with a 20-25%ish high point. It does however have some swept back wing stabilization effects from the high point (and section CP) sweeping back towards the tips. It seems real solid in a gusty breeze that bats a Ringmaster around rather badly.

I might try a bent I-beam on another one to free up some space at the tip. The front leadout probably wants to be about 1/2" forward, but there just wasn't any way to put it there without compromising the straight I-beam's strength.
Old 10-26-2007, 09:11 AM
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My thought on seeing your first wing picture was that I would have swept the spar back, I've run leadouts through I beams and box spars with no problem. Maybe a little reenforcement, but there is little aerodynamic force on the wing tip. So, as long as you don't pick the airplane up and try to hold it level by the inboard wingtip, should be no problem.
Old 10-27-2007, 11:14 PM
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Default RE: My new Avenger

Tonight I reduced the throws on the elevator down to about 30 degrees in each direction and evened out the balance between up/down some (it had a bit more down than up previously). Noticed there was still maybe 2 degrees of rudder offset and took that out too.

Some time next week I'm going to cut the adjustable rudder off and replace it with a 1/8" sheet fixed one (the adjustable is 1/4" stock). That will knock some fraction of an ounce off the back end allowing for some nose weight removal.

Weather permitting, we'll see how this all works out tomorrow.
Old 10-29-2007, 07:14 PM
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No joy so far. Local weather has been too windy to risk it. We're seeing the outer fringes of the tropical storm and that's going to persist for the next few days. Grrrr.
Old 11-01-2007, 11:02 PM
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Hi..nice looking bird there...since I see you are doing the S tigre thing..I have a few questions,,,,I am attempting to re enter the world of C/line after 15-17 years off ..have a few old Enya .35 engines and Super Tigre C 35 and the G21 versions...question...have oiled these guys up,have strong compression..they "pop" like crazy..and were always very easy starters....always 3-4 flips and it was off to the races...mounted an Enya and a G21 ..(they are all >35...sorry.)...fueled them up..chocked till I got "bumps"..and then flipped like crazy..they were hitting..but never seemed to take the fuel and run....have taken the needle assemblies out and soaking in thinner...the Enya and the Tigre both have only 1 hole in the spray bar....as I recall...this is supposed to point straight down the throat of the venturi with the angle of it...Isnt that right....? Ok..now on the Tigers the spray bar is actually behind the venturi..So...where is the hole in the spray bar supposed to point....? Will try to run these babies again with spray bars re-installed...and new tanks...Can anyone think why these are not firing up for me,,,they were put away oiled and clean..someone said to "cook" them in a crockpot with antifreeze...or take them apart...I am all ears...and waiting for the advice from flyers of today....The credit card is on the bar...this rounds on me...thanks in advance...joe in Houston
Old 11-02-2007, 07:49 AM
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I have two C35's and they're both one or two flips. The hole in the spray bar should be oriented perpendicular to the venturi on them (i.e. aiming towards the front of the engine).

An engine that's been stored full of oil will load the plug with gunk pretty quick. Unless its packed in like cosmoline, letting some raw fuel sit in it for a few minutes while shaking it around should free up it up. My Enya .29 sat for a long time and I didn't have to take it apart to get it running again.

If your tanks are old and used, a fuel filter is a must. You might fill'em full of acetone or MEK, plug all the vents, and let'em sit for a day or two shaking every once in a while then blow the stuff out the feed line under pressure with a fuel bulb. A couple of treatments like that and most of the solvent soluble junk gunk should be dissolved and ejected.

There might be some water soluble gunk like solder flux residues left too. Some nice soapy dishwater shaken around for a while can get that. Keep flushing with clear water under fuel bulb pressure until you don't see anymore suds coming out. The dregs of the flush water are soluble in alcohol. Some rubbing alcohol will absorb the water and get that. Then a dash of fuel shaken around will pick up that flush alcohol and carry it out too.

Another thing I've seen that could cause a problem was a pickup line with a hairline crack running the length of it that was bleeding air in. That only happened to me once but it was a real puzzler for a while.
Old 11-02-2007, 08:07 AM
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Default RE: My new Avenger

Other possibilities:

When you say not hitting, do they run off a prime? Before hooking up the fuel system, make sure it runs a prime. If not, change the plug. Some oils used to store engines will ruin a plug.

Are you running with the needle too far open? Perhaps it is dieing rich. Close the needle and open just enough to pull fuel when choked.

Make sure the tank is low enough to not flood the engine. I would suggest top of tank at or below needle valve while on the bench.

I think everything else has been covered...except - make sure the new fuel has 20%-25% lube, preferably all or at least half castor for iron/steel engines. Many fuels used today are for large BB engines that do not need as much lube (~14%-18% synthetic).

George
Old 11-03-2007, 09:08 PM
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Default RE: My new Avenger

Thanks for all the help...replaced tank..easier than trying to clean the old one..new plugs...Running to beat the band...! .here is a funny...Had to make an ignition
battery..no one in Houston,texas stores that should sell these had a clue as to what I was talking about....took an old Everready square starter battery apart...Guess what was inside...4 cells about the size of D batteries..so off to Wal-mart...bought 4 D's...taped them all together..soldered the tops inline with each other..and the bottoms the same....connected the wires....Bingo..solid 1 1/2 volts!dont know why everthing is so %$%$^%.. Yeah I know Brodak sells the battery , but he want more in shipping than the darn thing cost...try as I may..just can't play that game...

an old fart signing out....Happy Flying
Old 11-04-2007, 06:00 PM
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I use a Cyclon 2 volt 5 amp/hr lead acid gel-cell like used to be in your Glo-Bee Fireplug. You can get them at Batteries plus. I use my old Glo-Bee charger, but I'm sure a suitable one is available. Your D batteries will work fine.

Have you been out to Scobee field yet?
Old 11-08-2007, 04:40 PM
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Default RE: My new Avenger

Well, I just bit the bullet and did some surgery to move the front leadout forward. I got it exiting immediately in front of the spar going through the LE. Not the most graceful looking lashup, but it feels solid enough and the LE isn't carrying much on this thing anyway. If it still needs more, I can relocate the rear leadout through the old hole that's still there for the original front leadout.

I also swapped out the ST C35 for my Enya .29. I put one flight on that combo today and its fast even with the Enya .29 and this thing is almost 500 square inches. If I do another one of these I'm going to thicken up the wing to slow it down. I think the highly tapered tips are the culprit here.
Old 11-08-2007, 07:27 PM
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Well....here we go..Got everything working,,I thought..bench runs on the older engine..Super Tigre G-21 .35 Evidently these older hot rods do NOT like the new synthetic lube fuels...OUCH..! Evidently it got too hot..old engine..new fuel= Bad Combo !!

Anyone know where parts for this engine are available,,,found bearings at Boca Bearing...$15 for both ball bearings....would like a piston/sleeve set...havent found anything yet...any help appreciated....got a jug of Ritche's Brew..10% all castor...hope that will eliminate any future problems..

comments apprerciated ..thanks ...joe in Houston/santa fe

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