sgilkey

My Feedback: (180)

Having watched the bladder guys, once you have a system sorted out, it looks like the way to go. my problem is i just haven't forced myself to adopt the bladder system. it would mean a total re-do of my fleet to find a place to put the bladders, while new construction would be easy I don't want to have a mixed fleet so I stick with the simple suction system. Watching ROID in action, he handles the system very easliy and smoothly and it solves a lot of potential problems. Since you're starting virtually from scratch on your combat fleet, you might want to consider "taking the plunge". Sure bladders have some drawbacks but so do suction systems. I saw Lee pop a bladder seconds before start at the NATS, he has anticipated this problem and his bladder cavity has a drain, he has a spare made up and he very calmly inserted his spare, refueled, and had the engine going in probably less than 30 seconds from the burst. I too have used the Hayes 3 ounce tank with success, it is enough for an SSC heat but you must be careful to get a good floppy clunk line, the tank is so short that you need to use very flexible line to get good clunk motion- i got some small soft tubing from McMaster-Carr. The hayes 4 ounce tank is easier to set up in this regard and if you use the soft Sullivan medium tubing it will have good clunk motion. AJ taught me a trick that has worked well on the AVENGER profile-type fuses, stick the HOOK side of sticky-back Velcro (Available at home Depot, etc) on BOTH the tank and fuse, then put a layer (i use about 3/8 inch think) of foam rubber between the tank and fuse, the hook side of the velcro bites the foam and keeps the tank from sliding. then GENTLY wrap with a strip of velcro (or I use packing tape) to secure to fuse, wrap so loose that you don't compress the foam. this solved the foaming problems I had on the SSC planes. On Brian's B AVENGERS i was able to mount the tanks with two-sided tape with no foaming problems. for sealing the LA backplate I use HILOMAR, a non-hardening sealer for auto water pumps (available at auto parts stores), it has the consistency of RTV but does not harden, so it is much easier to deal with on disassembly. or you can use the FP backplate which is cheap and solves the loosening problem but i'm not convinced it's the best for durability as it is shorter, and therfore the rod can come slightly off the crankpin which seems to me less than ideal for big-end bearing life. but guys have been using the FP backplate with success so what do i know. if you have access to a machine shop you can machine the sealing surface of the FP backplate to let it extend the proper distance into the LA case. or you can use the Magnum XL 15 which does not have backplate problems but has a soft crank and a finicky carb needle. Or you can use the TT GP15 which has none of these problems but has a HS needle that is easy to break off, ruining the whole carb casting. What the world needs in addition to a good 5 cent cigar is the 25FX-equivalent of an SSC engine- reliable and durable out of the box. I use the FP15 which has none of these problems and is very reliable and durable but it is not as powerful as the LA, it's the rare FP15 which will hit the 17.5k limit in my experience, while it seems many if not most LAs will.

Montague

Lou,

It's funny that you say that bladders are as easy to use as tanks. You really should go back to the RCCA forums history and read your own posts back when you were first trying out bladders, and the posts of other guys trying bladders for the first time. It's an amusing read to say the least .

Once you are used to bladders and have a system all worked out, there is no question that they are as easy to use as tanks. And if you have an experienced guy there to help you, it makes bladders easier to learn. Lou learned a lot from Lee, for example. Learning it on your own, with out someone there to show you and help you trouble shoot is not as easy.

Keep in mind that learning the ins and outs of clunk tanks isn't exactly easy either. It's just that most all of us learn how to make clunk tanks work when we learned to fly on our first glow fueled airplanes. As an instructor here at my club, I've spent many hours going over how to make a basic fuel system work with newbies.

My point is that if you are new to combat, keeping the number of things "new" down to a reasonable number helps. And you don't "need" a bladder. Anyone who's seen me, Chris Quinn and many other guys fly quite well, and get plenty of power on normal tanks is plenty of proof of that.

(also, fwiw, I don't have any problem with the Hayes 3oz tanks using the black tubing that comes with them. Go figure).

(another side note. SSC wings are getting thinner and thinner. My wings have never been thick enough to put a bladder in. And I really don't want a 3-4" long spoiler sticking out of my wing if I can help it. I've never done flight testing to see if that lump results in a noticeable performance drop, but it can't help . And it is true that my "new" wings are faster than wings that have been in a couple of mid-airs and have the wrinkles in the covering as a result. Of course, I could fit a bladder in to my fuse with a bit of re-design, but I don't see a reason to bother)

Lou Melancon

Hi Kirk,
I actually used bladder tanks in CL Combat planes in the 60's (we used baby pacifiers then) before the plastic clunk tank had been invented.

Most of my troubles were from needing to find the materials needed to make and run bladder tanks. They don't sell the parts at the Hobby shop. But once I did find all the parts it became much easier for others to duplicate the success we were having. That's why I published the article on how to make then and where to get the parts. The Pioneers are the ones with arrows in their chests.

There are drawbacks to bladder tanks. Scott and you both make good points about putting them in wings. You really need to be around someone running them to see how they work and how to use them. Also you really can't use the throttle with them except for maybe the last 30% of its range. But, even with the drawbacks, the performance benefits of reliability and repeatability have been so good that I'll continue to use them. Please note that I am not advocating that anyone try them, just relating my experience.

Capn America

My Feedback: (3)

I am going to experiment withn a bladder tank over the winter and see if i can put it inside a fence post fuse. No time to try one out before the brickyard event this weekend, gotta go with what i know. Amorall really helped last night.

New question:

Avenger has a small flight problem. left turn it rises in the turn, Right turn it drops to the ground. Left side G-10 is cracked and allows the motor to pitch off to the right. Right thrust would cause this problem or possibly the stab is not true enough? Going to fix the engine mount today and test fly it again tonight. Using a single aileron servo so there is no mismatch in aileron differential or anything.

sgilkey

My Feedback: (180)

if you follow the materials list in Lou's article you'll have the right stuff for your bladders, based on what i saw others going thru I wouldn't recommend experimenting as the wrong stuff is, well, not right! take advantage of what others have learned and are willing to share, copy shamelessly! i forgot to comment on the aileron gap seal tape, i use it on the SSCs too, i figure if it eliminates flutter on fast planes then flutter must come from turbulence and turbulence means drag so might as well reduce drag even if it doesn't lead to flutter. not sure it's really helping but it takes 5 minutes per wing so i do it anyway. on your turning problem, one possibility (though i'd say remote) is your lateral balance is WAY off. if the plane rolls OUT of a left turn and dives INTO a right turn, that is a sign that MAYBE your right wing panel is much heavier than your left one- when you yank elevator, the heavy panel having more mass than the light one tends to make the plane roll in the direction of the heavy panel. This was a common tuning step when I raced Q500 and when i started combat I used to add tip weight to my wings to try to tune this attribute out of combat planes. I stopped doing it long ago as I found it really did not seem to be necessary (you really can't statically balance laterally IMHO, it's much better done with flight tuning). I can't remember the last time I added tip weight to a combat plane. I just keep adding elevator until I don't get a stall/snap. It's possible you just have too much elevator and your right wing panel, due to a twist or something, is consistently stalling before your left one and that's leading to the roll. But you can try adding some tip weight, i used to just make a slit in the tip foam with an xacto and cram pennies into the slit, put tape over them or they might pop out! if tip weight doesn't help, try reducing the incidence of your right panel (twist it and iron it to add some washout).

Montague

I still do balance my wings when I have time. I don't always do it, but when I do, I can turn a little tighter. Basically, I first try to make sure the vertical stab looks true, since if it's twisted (common with coro stabs), that will cause the kind of thing you are seeing.

Once I think the stab is true, I'll do turns in both directions, and if the plane always rolls out the same way, I'll add a little weight to the light tip, and try again.

However, at the field or a contest, if I have a plane that shows this tendancy in trim flights, I'll just apply some rudder trim (by grabbing the stab and twisting it), and that can often counter the effects of a wing being a little heavy well enough.

Capn America

My Feedback: (3)

I will wheck that as well, but i dont think that is it. Its not a snap roll problem either, its at any turn radius not at full elevator throw. Im also going to build a spare wing tonight so i have one for sat. If nothing else i will swap them out and see if the wing is twisted or something... Also noticed that it rolls one direction much faster than the other with the same throws. Really hate to have to to this last min, load it in the truck and go run it but that seems to be the way it works out for me.

Montague

sounds like you might have rudder trim and are compensating for it with aileron trim for level flight.

Capn America

My Feedback: (3)

Allright, I changed the stab, straightened the motor mount and reinforced it, balanced the wing on the fuse...7/10 weight on the right tip and flew again. Same problem. rolls left well, right slow and the travel of ailerons are identical. left bank turn it climbs right it drops. I would have to program elevator up in a right turn to stay level and down in a left to stay level... Really has me confused.

Possibility: wing and elevator out of alignment? If the wing was not exactly in the same phisical plane as the elevator it seems logical that it might influence the turning like this but shold not affect the roll rate i would think. I am stumped. 20 hours till i leave for the brickyard and im still not happy with the way it flies. Guess i will try to check the wing to elevator relationship next and fly it over lunch break tomorrow and see if i gain anything. Building a new wing just in case it has something to do with this one but i could use some more ideas.

aimmaintenance

"Hotwheels" I would suggest (by looking at the time you posted last) that sleep deprivation may be a bigger problem than roll rates.
OK nevermind,,,,,, what time is this forum on anyways?

Capn America

My Feedback: (3)

To further complicate things, i went back out last night and measured the wing to elevator alignment and at 6" of center they are within 1/8". At the tips it definatly has some lean to the right by an inch or so.

Fuse is now straight, maybe left thrust? I talked with AJ last night and we discussed adding weight to the left tip to balance the flight . Might work but would really make it heavy to the left as i just added 7/10ths to the right to static balance it. It might pull the left down in the turn but how would it help the right? Going to give it a try , nothing else is working.

I am about to give up and progran 120% right Al and 80% left, couple elevator to ail and put a little up with left and down with right to make it corner straight. It seems though with that combination of mix to correct the problem it should be obvious what would fix it. But its not...

sgilkey

My Feedback: (180)

given your differential in roll rate i would guess you have a wing twist, it's not that hard to build one in! we build our wings with flat tops by gluing the spars in the slots with PU, putting a long strip of waxed paper (not waxed legs like Aaron's) on the floor, gently "tweak" the wing to slide the spars in the grooves to give your plane excess dihedral (it'll be elliptical dihedral like a Hobie Hawk), lay the wing on the floor top side down, and then put weights on the wing to press it flat agains the floor- paint cans, old batteries, etc, just make sure the wing is pressed flat consistently along its length, and that the weights are placed such that they are not causing the wing to twist but are just pushing it down. This of course presumes your floor is reasonably flat... Some time ago I gunsighted some wings i built and they were not flat but wavy, pretty ugly looking so i adopted this method and it seems to give me straighter wings. but i still do occasionally get one that rolls way better in one direction than the other (it's pretty typical, for me, to have the plane roll slightly better one way than the other) which i try to compensate for with ATV. one other thing is, depending on your aileron linkage geometry, you can actually get MORE throw than you need for max roll rate and you can get less roll rate with the added throw. assuming you have programmable ATV on your radio, while flying, observe your roll rate and then start dialing OUT aileron throw 5 or 10% at a time and look, you might see the roll rate doesn't get any slower (which means you're saving throw and therefore drag) and it might even IMPROVE. good luck, wish i was coming to Indy to kick your butt.

Capn America

My Feedback: (3)

I will try the reduced rates before i swap the wings out. I have the new wing built, just need to tape it up and throw a servo in it tonight. See how it flies tomorrow.

As for kicking my butt, Ill have more stick time when we meet again. Ill catch you, then that Brat of yours is next on my list

sgilkey

My Feedback: (180)

yeah, join the club, he's on MY list too.

aimmaintenance

Once I decide to quit lettin you all win, you'll all go down.
I'm just worried that if I show my REAL stuff everyone will just quit!

And by the way. I DON'T WAX! (NAIR WORKS FOR ME)

Capn America

My Feedback: (3)

I think it was a twist in the wing. I built a new wing friday night and it flew a lot better sat morning right up to the first mid air of the first round. Broke my new wing, fuse and needle valve. It was all downhill from there. Full debrief of my first ssc event is coming, lets just say i was not impressed....

Montague

sounds like some really rough luck there. It sucks getting good gear taken out early, but it does happen to all of us once in a while.

Capn America

My Feedback: (3)

I still mananged to fly 9 of the ten rounds offered sat. just kept me hopping all day staying ahead of the 5 or so midairs that followed. wing swap and repairs nearly every round....

Montague

You'll have days like that.

But with practice, you can actually learn to avoid mid-airs, and you'll find they go down a bit. The trick is to start thinking tactically, not just going straight after whatever you see. And staying out of the middle of the furball, so you aren't crossing right through most of the traffic.

DEF

Getting back to bladder tanks, if you tie a rubber band around each end of the bladder you can hang it on the wing dowels under the wing. Worked great on my sscAvenger and should work on a fence post.

Fred420

My Feedback: (1)

Here are some pictures of the Brickyard that my wife took. This was my first event and I want to thank everyone there. This is a great bunch of people and again, Thank you.


Fred420

Skull Man

Marine Dad,

What is it you were asking.....Looks like the focus turned to "how to use a bladder tank"!QUOT!...hehe

Don't get me wrong, but you got derailed

FlyingGreg

My Feedback: (4)

Hey guys--I've been away from the combat threads for a while. Nice to see Lou, Scott and Kirk still posting like crazy. Lou, I tried your bladders, and just made a mess of everything. Engine (OS) would flood immediatley. It took two of us to start the plane, one guy slowly releasing the forcepts while the other spinned the prop and modulated the needle. Flew ok, but too much trouble for me. I had a couple of tetra bubbless tanks that worked great. Probably a little heavy, but no foaming.

I agree with everything you guys said about SSC and how it has become more popular around our area as well (Cincinnati). We tried to do Limited B this year in Hamilton, but I think most guys preferred SSC. I liked Kirk's three levels of fliers--I rarely get thru a round without a mid air--lots of head ons as well.

We just moved our field after the city ran a new access road through our fly area. We are about a thousand yards northeast of where we were. Hope John Labarre will run a couple of contests next year, but his real pilot job at Delta has taken him away most weekends.

Best regards,

Greg
HAWKS

Which_way_is_up

I would have loved to have seen that. . . . . a varation of the joke . . . .how many XXX(fill in the blank) does it take to change a light bulb!

MarineDad

My Feedback: (10)

Never mind. I think I got my answer from reading this thread, and from seeing what went on in the RCCombat threads. Perfect example of what you guys have been forced to put up with.