1st flt Avid - impressions

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Posted

The Junkers- style flaperons have the advantages of the CP peak reduction of a slotted flap if rigged correctly, and of not inheriting the wing's tired boundary layer, but at our scale tend to develop their own wimpy laminar boundary layers, which limits their max CL,  and contribution to roll authority.  It may be possible to trick them into early transition to the much more robust turbulent boundary layer with an appropriate level of surface roughness, which is likely quite fine.  Teensy VGs could also be effective in this, but it's relatively easy to overkill the problem and make things worse.  In any case, there's only so much even a slotted flap ( in our case as an aileron) can do.  Having studied the kinematics of the mixer mechanism, I was somewhat unimpressed to see greater down deflection than up deflection as flaps are lowered.  I think there is a cure, with a different mixer geometry.  Leni says they overpower the elevator at the higher deflections anyway, so maybe it's a moot point.  Maybe they are just the ticket at 15 degs as-is.  I need more experience flying the bird.

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Posted

More down than up deflection.. Well known well documented issue.  The F7a arms help to fix this.  You have to get into the designers head to really understand why it is why it is.  Folding wings by just pulling 2 pins and folding them back.  The only way to get them to work was wit the mixer system set the way it is.  its called design trade off.  give a little hear for the better of the overall design goal.  Others have changed the arms in the mixer even more so that just the swap to the F7a arms and you have to pull the bolts on the flaperon linkage horn and manually roll the flaperons up then fold the wings.  it doesn't do the magic all by itself.

Can there de refinements to the design.  Yes for sure.  Is it worth it for minimal gains?? that's a question only you can answer for yourself.  Several people have spent a ton of money trying to turn an avid or a kitfox into a supercub, its not going to happen.  Gas through the tanks is the single biggest performance enhancement you can do.  I see guys with 200K + planes that can't fly them even close to the planes potential.  I personally would not start mucking with anything on the plane other than get the roll out of it by adjusting the rod end and getting your CG back to about 16" with some weight on the tailwheel and just fly the crap out of the plane till it becomes a part of you, then you can start making little tweaks here and there if you want to. 

Again, Just my opinion.  Put that with 5 bucks and you may be able to get a cup of coffee these days.

:BC:

 

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Posted

Ya know just to see if it could maybe be done I went to work and designed a mixer for my avid that should produce like 2.7 to 1 differential and still allow the wings to fold without disconnecting the controls.... Everything works.... on paper. Just a matter of getting ambition up and building the components and seeing it if actually works on a physical plane. And that is the reality. Don't have the time and ambition to tackle it. Would take a lot of time or money or both probably. Just not in the mindset to do it. Then there is also the question of how much up travel on the alerion is structurally acceptable. My plane fly's without it. for now.

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Posted (edited)

So how do they say this... If it ain't broke, don't fix it...?

Not all planes are alike. The Avid Flyer takes a lot of footwork and some getting used to but it has a very sane behaviour. While no one will say it is the easiest plane to fly with clean turns there are no real traps to fall into. 
But it takes a little time to fully appreciate (well, that was actually very fast) and master (takes a little longer).

Get some airtime before deciding what to change, if not you might not improve your plane but degrade it. By degrading I could mean just that (depending of what you used to fly before...) or change characteristics of the plane that you with more experience would have appreciated (or no longer noticed).

I changed to the the F7A bell cranks, they have a positive impact but do not transform the plane (it still need an active pilot - luckily as that is one thing I like about it...). With just the F7A mod you do not have to disconnect anything when folding the wings.

Regards

Fred  

Edited by FredStork
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Posted

Checked wing incidences with inclinometer & found them to be equal to within 1/10 of a degree, the precision limit of  my tool.  Also found an area on the port aileron where the trailing edge had been bent up, likely hangar rash.  That could explain the roll moment.  Bent it back down as best I could.  We'll see if I got all of the roll moment out.  This may take several iterations.  Turns out I have the older f7 mixer arms.  No matter; Just need more airtime.  If my new, stiffer trim spring works with some flap, I'll be tickled silly!

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Posted

Checked wing incidences with inclinometer & found them to be equal to within 1/10 of a degree, the precision limit of  my tool.  Also found an area on the port aileron where the trailing edge had been bent up, likely hangar rash.  That could explain the roll moment.  Bent it back down as best I could.  We'll see if I got all of the roll moment out.  This may take several iterations.  Turns out I have the older f7 mixer arms.  No matter; Just need more airtime.  If my new, stiffer trim spring works with some flap, I'll be tickled silly!

I would love to see a bolt on design where the flaperon is separated where one part is flaps and the rest is aileron.  Leni has a plane with that design already.  Be nice to put some larger flaps on the avid and get is slowed down to 30. 

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Posted

Turbo.  If the washout is the same in both wings, next time you fly, pull in just a little bit of flaperon.  Not sure why, but it might make the plane fly straight.  Like I said, I'm not sure why, but I've seen it work on other Avids.  JImChuk

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Posted

I had the carbs apart and they are clean, including the idle jets.  The floats had sunk, so I had to buy new ones.  Gotta look to see what size those idle jets are, though.  Joey flies out of somehere near Fairfield, which has to be less than 100 ft elevation, so maybe the #50 idle jets is a good call right out of the box.  I too will be flying out of fields at less than 1000 ft elevation.  Totally agree re static idle rpm vs on final - part of why I had a tough time getting the bird down.  Trees at approach end of runway & short strip - bad combo for green TW pilot in unfamiliar bird.  Smooth at 1400 static is my new goal!  Next time The Dalles with 5000 ft, 100 ft wide tarmac!  Just loved putting around the verdant Hood River valley & hills, though.  This is why airplanes have such magic.

 

Aircraft spruce has the jets , about $60 a piece!!!! but they make it run better....

60 dollars a Piece what a load of crap. Any motorcycle shop should be able to get you any jet you want for 5 or 10 bucks a piece

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Posted

Had 2nd flight July 26th. I found that I have the #50 idle jets, and backed the air screws out as far as I could before the o-rings started to uncork.  Adjusted idle speed down to 1800 rpm.  Idle was much better, and the bird would descend for landing just fine!  Lifting the tail helped tame the takeoffs, but green as I am, I had difficulty judging height above the runway on landings. A couple were a bit hard as I stalled too high above the runway.  I am now thinking that holding it off as long as possible is not a good plan - rather better if I just flare to a low sink rate by parking the nose relative to some reference like the end of the runway or the horizon and let the ship settle.  I am still way overcontrolling rudder on runout, and need to mix in more subtlety, and stop being such a nervous Nellie.  As Leni says - "more fuel thru the tanks" is the answer.  I'm still a little skeered of the beast,  but  JimChuk's grin is starting to appear on my face.  Can't wait to land into a headwind!  Oh yeah - I went to a different airport with no glider ops, and a longer, wider runway. Whew!  Love the smooth response of the 582, and the bird, even with all those unnecessary openings in the front of the cowl, and big bellyrad, felt slippery!  Measured 80mph at 4500 rpm.  EGTs were above 1000F everywhere except at idle, not optimal, but in the range.  CT was rock steady at 150F.

I have just cut up a beer coaster for use as a friction disk for my cheeseball trim system, but now have to reinstall the stbd bungee.  Cork for the disk might have been better.  Thoughts?  Trim will sure be welcome!    Full flap appears to not be anything near 25 degs, more like 15 on one side with stick full over! What gives?   -Turbo

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Posted (edited)

Try adding a little power during your flare and slowly fly it onto the runway. As soon as you touch cut the power and flaps. I am not good at judging where the runway is either, that's why I add a little power at the flare and let it settle in.

Edited by Bandit

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Posted

Thanks, Bandit.  Will give it a try.

 

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Posted (edited)

I say your flaps are fine for now.  Until you really get a feel for your bird, the flap down 15 at full stick deflection will never allow you to get into a control reversal situation.  Where the drag of the down flap overcomes the roll input of the up flaperon and you bingo, the nose rapidly swings the opposite direction and you crap your pants.

These planes were designed and set up a bit conservative by Dean.  The thought and dream was for a guy to build a plane in his garage and learn to fly in his creation.  Keeping this in mind, he kind of tried to keep it idiot proof and tame.  What happens when you build something idiot proof.. well WE DO!  yes, we make a better idiot :lol: .

 

So the design has evolved from a knock around the local area slow flying forgiving airplane to us wanting the cheapest plane we can get our hands on and seeing just how far we can push it.  In pushing it we have figured how to add at least 100 pounds to the empty weight, figured out ways to make the same wing area haul more weight and then we decide we want to make this slow draggy airplane go faster, and slower!

This is the exciting and wonderful world of experimental aircraft.  Where men act like little boys and see how much they can modify a toy and make it do more than it was designed to do. To top it off, it seems to give us great pleasure to do so and we as humans can never seem to just be satisfied with what we have.

All that being said.. The more flap input you have the more up elevator you need or the larger you need to make the elevator.  If the stick is not in your lap on landing then your leaving some short field performance on the table.  This begs the question... if you have 6000 feet of pavement on the runway do you really need to be landing on the numbers then taxing for a 1/2 mile to turn off..

As I have said before, before you start tweaking on the plane (other than adjust the rod end to make the wings fly level or adjust CG to make it handle better) put gas through the tanks.  Lots of it.  Make so many turns around the pattern that you can do it without looking at the instruments.  you feel it in your butt and you hear it in your ears with the tone of the engine.  Don't start by trying to focus on making every landing perfectly on the numbers, focus on getting it safely on the ground.  Do not be afraid to use power to arrest sink rate.  Elevator controls speed, power controls sink rate when you are trying to fly precision approaches. (that is kind of an oxymoron in a 600 pound plane but I think you know what I am getting at).  Some destructors will slap your hand if you touch the throttle after you have pulled the power.  This may be good for initial training to make sure you know how to keep the runway within reach in case of a power failure but at this point, we are not in 1st grade anymore, we are the bright and shining know it all 7th graders with something to prove in a new school.

so here we go.  You are looking down the runway on final.  Is your chosen landing spot staying stationary? sweet!  no, its creeping up the screen, add power.  its slipping down the screen?  pull power.  here we go, nice and steady, your right leg starting to shake a little bit, sweat beading up on your brow, the seat sucked so far up your butt you can take your seatbelt off and stay put in a -10 g wing ripping outside maneuver.  Breathe,  shit, don't forget to do that.  relax, the stick between your legs is just that, its not an ax handle, its not going to fly out of your hand or try to run away from you, relax your grip a bit and enjoy it damnit.  hold what you got with little inputs, little blip on the power here and there, little movement on the stick, your trying to make the moment last, your moms not gonna walk in the room so you don't have to finish so damn quick.

Keep in your mind that these are high drag airplanes.  Excess speed is going to go away really fast when you pull the power and pull the stick back.  Hold your approach angle and when you start seeing the shadow on the ground reaching up to meet your tires getting smaller and smaller out of the corner of your eye start slowly easing back on the stick.  Add more power if it starts to feel a little sluggish.  keep that going as you see that huge shadow get smaller and smaller until it just kisses your tires and you get that little bump and squeak as the tires grab mother earth again.  YOU ARE NOT DONE YET!  pull the power out and stay ahead of the plane.  dance to the music and let your feet feel the rhythm.  it is amazing how good a white boy can dance when you just relax and let it happen instead of thinking about it.  You have trained for this, you have been doing it your whole life.  You have to stop thinking that there is only one way to do it perfect and just let it flow.  The punk kids sitting  on the side bleachers you think are making fun of you on the dance floor but guess what.  You have your lady on that floor and your smiling while they are just sitting there wanking it wishing they had the ballz to ask a girl to dance..

She is your lady and she responds very well to your touch.  Take her out dancing and having a good time and you will be rewarded with great feelings and big smiles.  Also keep in mind that no one starts off doing a perfect elegant waltz.  You gotta just get out there and get jiggy with it and learn the waltz.

:BC:

 

Edited by akflyer
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Posted

But Leni, you are a poet!    I gotta admit that my fear of that embarassing groundloop has my dance steps a little choppy and nerdy-looking.  I'm zigging & zagging along the runway desperately trying to keep it on the tarmac, never mind the centerline!  I keep imagining myself the day's high amusement for the other fliers at the airport, but so far am not hearing the murmurs or seeing any smirks.  Perhaps they recall their own rights of passage.  Thank God the true terraphiliacs are blind to my plight!  Thanks for the advice and encouragement.  Gas thru the tanks!  Banzai!   

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Posted

Leave it to Leni to describe how to land like that!:lmao: 

Turbo, Two additional things that will help to make your landings easier; find a grass or gravel runway (of comfortable size) to practice on and install wide gear if you don't have it.

Are you in Hood River, OR? I grew up there and get down there a couple of time a year to the home place there up near Mt Hood store.  I will be down there in Nov. but will be immediately going to MT to hunt, but would like to catch up with you when i get back to HR if you are around.

Randy

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Posted

Leave it to Leni to describe how to land like that!:lmao: 

 

What can I say.. Gotta put it in terms a man will understand.

:BC:

 

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Posted

Randy,

I live on the other side of the Columbia, in Mill-A, but it will be fun to meet and compare notes.  Just let me know when you're in town so-to-speak.  HR airport has grass, but also the dreaded glider ops, so I am liking CG regional in Dallesport, with its 100' wide and long runways.  Wind often dumps out of the Gorge and right down runway 31 there.  Gotta love that!

- Turbo (Art)

 

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Leave it to Leni to describe how to land like that!:lmao: 

Turbo, Two additional things that will help to make your landings easier; find a grass or gravel runway (of comfortable size) to practice on and install wide gear if you don't have it.

Are you in Hood River, OR? I grew up there and get down there a couple of time a year to the home place there up near Mt Hood store.  I will be down there in Nov. but will be immediately going to MT to hunt, but would like to catch up with you when i get back to HR if you are around.

Randy

Leni That is the best description of landing an Avid or a Kitfox I have ever heard.  With your permission I would like to reprint that in our club newsletter.

 

One of the things I find many of my students do is dance too much on the rudders.  Just yesterday one of my students was punching the rudder hard one way and then hard the other.  I try to explain that the rudder dance is gentle and easy pressure is all that is needed to keep the airplane straight.  Think of trying to keep a balloon in one spot by tapping it.  If you tap it too hard one way then you have to tap it hard the other.  Soon you are working so hard at pushing it back and forth you get behind it and that's when the problem starts.     Easy pressure usually works better.   By the way once I got the student settled down and using easy pressure his takeoff was smooth and easy.

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Leave it to Leni to describe how to land like that!:lmao: 

Turbo, Two additional things that will help to make your landings easier; find a grass or gravel runway (of comfortable size) to practice on and install wide gear if you don't have it.

Are you in Hood River, OR? I grew up there and get down there a couple of time a year to the home place there up near Mt Hood store.  I will be down there in Nov. but will be immediately going to MT to hunt, but would like to catch up with you when i get back to HR if you are around.

Randy

Leni That is the best description of landing an Avid or a Kitfox I have ever heard.  With your permission I would like to reprint that in our club newsletter.

 

One of the things I find many of my students do is dance too much on the rudders.  Just yesterday one of my students was punching the rudder hard one way and then hard the other.  I try to explain that the rudder dance is gentle and easy pressure is all that is needed to keep the airplane straight.  Think of trying to keep a balloon in one spot by tapping it.  If you tap it too hard one way then you have to tap it hard the other.  Soon you are working so hard at pushing it back and forth you get behind it and that's when the problem starts.     Easy pressure usually works better.   By the way once I got the student settled down and using easy pressure his takeoff was smooth and easy.

No need to ask mr, use it and abuse it.  You can remind the students that if they would like to get lucky it would serve them well to stop stepping on the ladies toes while dancing.  Besides that. being that nervous is going to lead to premature ground loops.. No man wants that! :lmao:

 

:BC:

 

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Posted

3rd flight today.  Just like Leni says, gas thru the tanks is what gets you there!  Found my tailwheel chain/spring arrangement had slack, and wondered if this was contributing to my ungraceful zigging & zagging post touchdown.  Moved some washers around to get rid of the slack, and presto!  I could smoothly control the direction I'm rolling at higher speeds!  My landings were not perfect, but way better than last time.  JimChuk's grin has arrived!  I am feeling like light at the end of the tunnel is not that of an oncoming train; that this can be done with grace...eventually!  In Leni's terms, that saucy Spanish gal who with body language and taunting look asked if I was man enough to dare try to conquer her has been given her answer! .

I learned to fly years ago in a C-150, and hated that sprung nosewheel steering.  My old Tri-Pacer had direct connection to the nosewheel, which I liked much better.  On the Avid, all that slack in the tailwheel connection to rudder must have some function, and maybe some guys just let the tailwheel swivel.  Being a TW newb, I dunno.  But in fast taxiing I have found that a more direct connection to that tailwheel is beneficial.  Is there controversy here?  Or is there a tradeoff I don't groc as yet?

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3rd flight today.  Just like Leni says, gas thru the tanks is what gets you there!  Found my tailwheel chain/spring arrangement had slack, and wondered if this was contributing to my ungraceful zigging & zagging post touchdown.  Moved some washers around to get rid of the slack, and presto!  I could smoothly control the direction I'm rolling at higher speeds!  My landings were not perfect, but way better than last time.  JimChuk's grin has arrived!  I am feeling like light at the end of the tunnel is not that of an oncoming train; that this can be done with grace...eventually!  In Leni's terms, that saucy Spanish gal who with body language and taunting look asked if I was man enough to dare try to conquer her has been given her answer! .

I learned to fly years ago in a C-150, and hated that sprung nosewheel steering.  My old Tri-Pacer had direct connection to the nosewheel, which I liked much better.  On the Avid, all that slack in the tailwheel connection to rudder must have some function, and maybe some guys just let the tailwheel swivel.  Being a TW newb, I dunno.  But in fast taxiing I have found that a more direct connection to that tailwheel is beneficial.  Is there controversy here?  Or is there a tradeoff I don't groc as yet?

Another Heinlein fan?

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Posted

Running the chains a bit loose will help the tail wheel unlock.  Easier for pulling 

into the hanger. 

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Posted

 

Are you in Hood River, OR? I grew up there and get down there a couple of time a year to the home place there up near Mt Hood store.  

I was just there the other day. That WAAM airplane museum is awesome. To be honest this whole Oregon coast is one of the funnest  vacations I have ever done.

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Other side of the super-river.  But yeah, WAAM in Hood River, OR, is great.  Huge collection of antique cars and airplanes. 

I think I'll keep those tight TW chains.  No hangar  to pull into yet, just trailer & garage. Still working on getting comfy with post-touchdown fast taxi.  It's hard staying off of those brakes.  Sorta glad I have the narrower stock gear, as wider stance would exacerbate yaw sensitivity to braking, although it's also clear that with the narrow gear's geometry, hard tarmac touchdowns chew up the tires.  Gotta work on greasing her on.

On the tailfeathers comment:  A big advantage of the flat-plate airfoil shape on the H-tail is its insensitivity to contamination.  The max CL is so low that in essence it can't go lower, even with serious mud & crud on the lower surface.  So the designer just sizes ithe H-tail appropriately, and we clumsy fudpuckers can't ever get into the deadly situation where the tail stalls, losing so much downward lift that we lose control.   Smart.  ATR turboprops scare me, as the H-tail is so small that tail stall in icing conditions is a real and scary prospect, especially with flaps down for landing.  I know - it has a de-icing boot, but what if the pilot doesn't realize he's got ice, or forgets to bump it off with the boot?  It has happened.  

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Other side of the super-river.  But yeah, WAAM in Hood River, OR, is great.  Huge collection of antique cars and airplanes. 

I think I'll keep those tight TW chains.  No hangar  to pull into yet, just trailer & garage. Still working on getting comfy with post-touchdown fast taxi.  It's hard staying off of those brakes.  Sorta glad I have the narrower stock gear, as wider stance would exacerbate yaw sensitivity to braking, although it's also clear that with the narrow gear's geometry, hard tarmac touchdowns chew up the tires.  Gotta work on greasing her on.

On the tailfeathers comment:  A big advantage of the flat-plate airfoil shape on the H-tail is its insensitivity to contamination.  The max CL is so low that in essence it can't go lower, even with serious mud & crud on the lower surface.  So the designer just sizes ithe H-tail appropriately, and we clumsy fudpuckers can't ever get into the deadly situation where the tail stalls, losing so much downward lift that we lose control.   Smart.  ATR turboprops scare me, as the H-tail is so small that tail stall in icing conditions is a real and scary prospect, especially with flaps down for landing.  I know - it has a de-icing boot, but what if the pilot doesn't realize he's got ice, or forgets to bump it off with the boot?  It has happened.  

no, the wider gear makes it a much tamer beast period.  The narrow gear is much more of a hand full.

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Leni is right. The wide landing gear makes it a whole new airplane.

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