Sign in to follow this  
Followers 0

Just joined the Fat Avid Club

207 posts in this topic

Posted

Vendor literature for screw terminal type Aluminum Electrolytics do tend to warn against mounting them with the seal end facing down.  A couple of examples are attached.  Completely your choice.

 

e-al_gui.pdf

UCC_PrecautionsGuidelines.pdf

Share this post


Link to post
Share on other sites

Posted

Not to stick my nose where it doesn't belong... but I would bet a pay check that Chris has valid reasons for mounting the way he did and that a lot of thought went into it.  I do believe that a sparky engineer is his job profession :lol:

 

At any rate, quit stalling mr, we have been waiting forever for a damn flight report!  I think you can stall a project longer than I can, and I am pretty damn good and not getting my project in the air :lol:

:BC:

 

Share this post


Link to post
Share on other sites

Posted (edited)

(Av8r_Sed is also an electrical engineer...  He's been my go to sparky on the Mangy Fox project, Especially since he told me why my first capacitor popped:  from being mounted wrong.)

Edited by Av8r3400
1 person likes this

Share this post


Link to post
Share on other sites

Posted

Didn't mean to hijack the thread. Back to Fat Avids!

1 person likes this

Share this post


Link to post
Share on other sites

Posted

I meant no disrespect!!  I just figured that as a sparky Chris had put some thought and reasoning into why he was doing it that way.  Everyone here has good contributions to the site and I was not meaning to step on any toes :BC:

 

Share this post


Link to post
Share on other sites

Posted

Av8tor

I was no aware of the screw base operating limitation. Thank you for providing the literature. I may switch to a pc mount cap that is not position sensitive. In any case the gas emitted is corrosive and I have seen many an aluminum electrolytic fail and do not want the electrolyte deposited all over the electronics in the panel should it fail. Thanks for pointing this out. It is a nuiance I was not aware of. That's the wonderful thing about this group. Always something new to learn!

1 person likes this

Share this post


Link to post
Share on other sites

Posted

Keeping our minds sharp. Always designing and building to keep learning. That's my attraction to experimental aviation. Glad I could help. 

1 person likes this

Share this post


Link to post
Share on other sites

Posted

This capacitor mounting position thing has been driving me nuts. By the way thanks again for pointing this out to me Av8tor. I have not messed much with screw terminal electrolytics even though I have a few laying around and it was one of those that I put in the plane after conditioning and verifying it held a charge for days.

So after a fair amount of searching, I finally found an explanation as to why position is critical on certain types of aluminum electrolytic construction. Here is the explanation from the Cornell Dubilier application guide:

Be careful not to interfere with the operation of the vent, for instance by mounting measures such as clamps, glue or potting compounds. In the case of large capacitors with the capacitor elements secured by thermoplastic potting, don’t mount them with the safety vents down as the potting may flow when the capacitors overheat and block the vents.

Anyway, NOW I understand why. The app not is attached.

 

AEappGUIDE.pdf

2 people like this

Share this post


Link to post
Share on other sites

Posted

Been a long time since I posted last. I lost access to this site at work which is primarily where I posted from. Now access is back.

I finally flew the Fat Avid for the first time this weekend. Been doing some taxi testing over the last week. The plane flew nicely with one HUGE exception.

This particular Fat Avid was a complete factory kit and it came with longer wings. About 33 1/2 feet wingspan with the additional fuselage width included. Each wing has an extra bay outside the flapperon and then the standard wingtip on the end. Bear in mind these wings were "factory".

When I first took off the wings had so much bend in them that the flapperons were super hard to operate and bound with little more than a few degrees of deflection. It was a bit unnerving, but I got it back on the ground safely. After much discussion and thought We reasoned we needed to see inside to check if the stiffener was missing or something from the spars. Also the plane barely fit in the hangar. So I cut the wingtips off, looked inside, found the correct stiffener, or at least it looked like it. I flat capped the end of the wings with vinyl tape. This shrunk the total wingspan by 3 feet. It made the wings the standard Avid length, but instead of a wingtip at the end the wing is boxed off square at the last rib. It was amazing how much less bend there was in the wing after removing the wingtips and how much better it flies.

What I want to know is does anyone else have the longer wing option on their Fat Avid and how did you deal with wing bend? And second HOW COULD ANYONE TURN OUT AN OBVIOUSLY UNTESTED CONFIGURATION? This long wing variant could NOT have been tested or they NEVER would have sold it....unless of course there was a different stiffener that was supposed to be installed in the wing than the one that is in there. But it came as a factory kit!

This is SO wrong.

Share this post


Link to post
Share on other sites

Posted (edited)

Hi Chris, glad to have you back on the list. (and still with us after that first flight)  Another guy on this list has a standard Avid MK IV that has extended wings, don't think he has had that problem.  Also, the Avid Magnum has longer wings.  I wonder if they perhaps have longer lift struts than standard Avids as well.  Kitfox went to longer struts on their Kitfox 3 and later for some reason.  I thought it had to do with increased gross weight, but maybe not.  On second thought on that last sentence, higher gross weight would cause the wing spars to bend more, so maybe that's the answer/cause.  Anyway, glad to have you back.  And maybe if Mark reads this, he can measure his liftstruts.  I'll now have to go out to the hangar and measure my Avid's liftstruts.  I found a picture I had showing the Kitfox 1's liftstruts are 98" from bottom bolt to front outboard bolt, (c-c)   One last thing, how wide is your fuselage where the wings attach?  JImChuk

PS  Avid MK IV liftstruts measured 91" and Kitfox 4 measured 108"

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted

My Magnum has longer wings like you said, but the spar attaches out further than all other Avids and the stiffener is different from the original MKiv too. The magnum wing has no visible flex whatsoever.

My first MKiv HH also had no visible wing flex whatsoever either.

These extended MKiv style wings (same lift strut position and construction) bent like crazy out toward the tip till I cut off the wingtips. There is still some flex although GREATLY reduced. I think the flex that is there now is because the lifting element goes out to the end of the wing as opposed to having a foot and a half of reduced lift from just the wing tip. 

Anyway it works well enough to fly safely I think now, but I cannot believe that this went out as a salable configuration. Really unsafe as it was. 

Share this post


Link to post
Share on other sites

Posted

Plane in final inspection before first flight, plane with wing tips cut off, closeup of taped off wing spar.

IMG_0297.JPG

IMG_0305.JPG

IMG_0306.JPG

Share this post


Link to post
Share on other sites

Posted (edited)

I believe all of the early Avid struts attach about 90" from root end of spars - Kitfox 1 & 2 with internal I-beam attach about 86", and Kitfox 3 and later about 96", except the Aerobatic short wing Speedster which is the same strut but attaches at 97" because there is no dihedral.  It would be nice info if someone would measure the Magnum and Catalina strut location because I didn't see it in the Magnum manual which I sold.  What about Avid+ and Fat Avid struts?  I would think that all the wings would have less bending if the 60" aluminum I-beam spar inserts that Just Aircraft and later Kitfoxes use in the 32' wings were used.  EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted (edited)

Hi Ed,  I measured my Avid MK IV and the Kitfox 4 lift struts today.  91" on the Avid, 108" on the Kitfox 4.  The Kitfox 1 struts measure 98".  JImChuk

PS, just reread your post, and I'm talking lift strut length.  You were talking distance out on the spar to strut location.  Sorry.....

 

Photo0164.jpg

Photo0165.jpg

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted

So what I want to know.....does anyone else on this board have these longer wings as delivered by Airdale and if so do yours bend a lot at the tips and how are you dealing with flapperon bind????

Share this post


Link to post
Share on other sites

Posted

It's like someone at Airdale (or where ever the Flat Avid came from) said "I want to extend the MKIV wings because I have this fancy wider and longer fuselage. Can I do that?" to an engineer friend, who then did some calcs and said "Sure it will work fine. The spar tubes wont fail and have sufficient safety margin" without even THINKING about the profound effect wing flex would have on flapperon operation. Then its as if they built and sold it as a kit without even testing. That's why I want to know if there were any other complete Flat Avid kits with the long wings. It is unnerving because the Fat Avid uses cables to drive the flapperons. These cables are not super strong in compression like the standard linkage, so flapperon bind could become a serious problem real fast.

OK I've vented now.

Share this post


Link to post
Share on other sites

Posted

Hi Chris,

Sorry to hear about your binding - maddening after so much work. I have Avid Mk IV #1602D, produced by Avid in 1992 iirc with 18" extended fuselage, no mention noted in the paperwork of the extended wings. HH wings, each being 1' longer for a wing span of close to 32'. The struts look to be nearly 92". I have seven flaperon hinges, at 2' spacing, on each side. No noticeable flexing of the wings and half of my limited time since purchasing it this spring has been in gusty (to 28K by local AWOS) or thermally conditions. Flaperons stop about one foot short of wingtip attaching point. No binding. Jabiru with RV6A nose gear (just purchased Grove taildragger gear for the future).

Pasco...I had my Avid there in April...on trailer enroute to Minnesota after purchasing in Oregon.

Beautiful airplane, wishing you well in getting it flying right,

Mark Johnston

Share this post


Link to post
Share on other sites

Posted

Hey Chris ,the Avid is looking good, I ended up adding the 18" extensions to the wing, I did have some binding in the flaperons on my avid + but it was due to crud and water that got into the flaperon pivot area, once we clean them up and got them moving freely I didn't  have any problems in flight. I only got 3 hours on it though in the spring and probably wont get any more testing on it till later this fall.

Share this post


Link to post
Share on other sites

Posted

Just thinking some more on this Chris.  Have you measured your wing spars?  Are they .083" or .065" wall thickness?  JImChuk

Share this post


Link to post
Share on other sites

Posted

My flapperon hinges were a bit stiff when I first purchased the airplane, but with generous application of mobile one at the hinges they freed up nicely.

Mark

Share this post


Link to post
Share on other sites

Posted

Thanks for all the feedback guys. My flapperons are definitely binding, not just stiff. When on the ground I get easy full flapperon deflection and full flap travel in all combinations. Once up in the air and the wings bend up, the flapperons are only happy in a very small range of travel aligned with the wing flex. 

We verified the bind with a friend at the end of the wing lifting it so one of the mains came off the ground. It binds up just the same as in the air. Removing the wingtips did a lot to reduce the problem but it is not anywhere near resolved. However I am comfortable flying it for the time being while working through this.

As far as 08 vs 06 thickness, when we removed the tips, I thought "is that 062???" My friend said "naw looks thicker to me". I will definitely MEASURE that tonight although I think it is 08.

At least I'm flying again even if it is more working out problems than just jumping in and going places! Like I've said before projects are great fun if you already have something to fly. I'm still trying to get there. I am a whole lot closer now than when I started this two week project 5 years ago! If I can get this resolved I can go back to plan A which is fix the Magnum!

Share this post


Link to post
Share on other sites

Posted

Hi Chris,

I am just in the process of building a new set of wings for mine and am planning to extend each wing by 18".  Now you have me wondering if this might cause me some troubles like you encountered.  I have built up laminated spar inserts for mine that are made with the original 18" long x 1/4" thick microlam insert epoxied to an 36" long X 1/4" microlam insert and with 3/4"X.125 2024 aluminum strips epoxied and riveted along the top and bottom of the 36" long side.  This should be considerably stronger and stiffer than the stock 18" Avid spar inserts but I am not sure how they compare to what you have in your Avid+. The lift struts I will be using are the stock Avid MKIV length.  Can I ask you to check one thing in addition to the spar wall thickness; that is can you shine a light in the spar and see what the insert looks like (thickness) and also see if you can get a tape on it from each end to see what the length of the insert is?

I was planning on extending my flaperons by 18" as well with an additional flaperon hanger at the tip rib but this would worsen the condition if binding is a problem so may plan to start with stock length flaperons and see how they work since I could add the flaperon extensions later by keeping the tip rib with the flaperon hanger tail.

Thanks for posting this and any further information you can provide.

Randy

DSCN2521-1.jpg

Share this post


Link to post
Share on other sites

Posted

My complete firewall back Avid+ kit was supplied by [old] Airdale with the same 144"L x 0.083" spars, 18" fixed wingtips, 141" flaperons and lift struts they supplied with the Mk-IV HH kit. Front spar lift strut bracket bolt hole is standard 80" from the root end on both, but the A+ kits were supplied with 18"L ply stiffeners vs 12"L ply stiffeners for Mk-IV. Distance between centerlines of A+ front spar carry thru pin bushing holes is 40-3/8".

To the best of my knowledge, wing extension kits were never provided as standard equipment to any A+ kits sold by Airdale. Based on my conversations with Steve Winder, I believe all seven complete Avid+ kits sold by [old] Airdale were delivered with the same Mk-IV wing/strut configuration as mine. The 12" wing bay extention kit was developed to extend the short spar speed and aerobat wings. The principals of Avid, [old] Airdale and Steve Winder were too intelligent and safety concious to knowingly promote and sell an untested or unsafe wing configuration and to suggest otherwise and malign them with zero evidence is inappropriate, IMO. Winder warned me repeatedly about wing and related structural issues when I was hoping to increase MTOW on my A+ and I detailed that year's ago in a thread here.

In any event, Avid and Airdale had no control what people do in the EAB universe. A more plausible explanation to me is that Vince thought the longer wing would buy him some extra performance (just like his choice to use a higher hp 912ULS vs 912UL) on his back country strips. He would not be the first to lengthen a long spar Avid Flyer wing, and you have two respond to this thread. Personally, I would be very hesitant to add wing extentions absent .083" wall spars and a much longer stiffener. I think Randy is spot on making longer stiffeners, did Vince do the same?

Share this post


Link to post
Share on other sites

Posted (edited)

Randy, If you aren't past the point of mounting your lift strut attachment points, I wonder if it wouldn't make sense to consider lengthening you lift struts.  The Kitfox 3 and later are almost 18" longer then the Avid and I think they use the same length on the latest planes, some of which go up to 1500 lbs gross weight.  Funny but Kitfox uses the .065" wall thickness spars on the highest gross planes they make.   I also think it might be a good idea to use the spar stiffeners like Kitfox uses.  They are 5' long.  About $40 each from Just aircraft I think.  JImChuk

Edited by 1avidflyer

Share this post


Link to post
Share on other sites

Posted (edited)

If I were taking the trouble of making new wings for an A+, I would use KF's Riblett airfoil, aluminum stiffener and flaperons. That wing is vastly superior to Avid's undercamber wing and anyone who has flown both knows it. The A+ teleflex cables would negate the need for a complete new flaperon control system, however, you would still need to modify the flaperon horn or change out to a different length cable. The 27-1/2" f/r spar spacing is direct bolt on and any needed wing sweep is easily accommodated for. It would be very interesting to see if the KF lift struts maintained the correct dihedral without modification. That would seem to be the biggest potential hurdle from what I see, although with a little foresight and calculation, adjusting the location of lift strut brackets slightly would be very easy to do.

Edited by dholly
2 people like this

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0