Avid B Sheriffs Auction on 10/2/18. 10:30am.

46 posts in this topic

Posted

The airplane has the attachment brackets to move the landing gear forward for tail wheel operation and by flipping them around from side to side the additional tie location for the suspension rubber works with the current gear that's on the airplane. I've seen You Tube videos of people doing this and while the gear is not ahead as much as the newer styles; those that fly this way say they have not had any problems.

I'm curious if the guy that nosed his over had any tail dragger experience? I've never heard of anyone holding full up elevator during a rev-up nosing one over? Anyone else ever heard of this? That said, all these Avid Flyers and Kitfox designs seem to have a short legged wheel stance. The tail hardly even begins to fly and they seem to take off. What happened to airplanes that required you to push the stick ahead to get the tail off the ground and then pull back once flying speed is established?

Anyone ever make an aerodynamic shaped skid plate that could mount in the nose wheel mounting tube? While you would still loose a prop in a nose over; a skid could help prevent damage to the lower cowl and allow your airplane to burn off energy while it slows down. Think of it as training wheels for transitional pilots learning how tail draggers differ from nose wheel aircraft.

Flapperon attachment points. Not a good photo, I took it before I purchased the airplane in the dark, unlit hanger.

 

flapperon.jpg

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Posted

The guy that nosed over wasn't flying or anything.  I think it was the first time he ran the engine, and onto it's nose it went.  The wheels are going to be about 6 back from where they would be if you use the right gear.  I would like a link to the you tube video where the guy says he swapped the gear as you describe with no problems.  I've taken off probably at least 1000 times in an Avid, and I usually lift the tail before I leave the ground.  JImChuk

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Posted

I have a friend who wanted to change from nose to tail. He moved the main gear to the forward attachments, taxied, light brake and on the nose. The only winner was me as I sold him my old prop...
There is no way you can use the nose wheel main gear for tail dragger configuration unless you fill up the trail with a large stock of spare propellers (don't forget to put the broken ones back in the tail when changing)... The geometry is different and the main gear get way to close to the CG. 

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Posted

what i know for tail draggers : the axis of main wheels has to be in the vertical line of leading edge when plane is in line 

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Posted

Here's a link for the non-believers. https://www.youtube.com/watch?v=e_F86gQ8A-U

Another gentleman at the auction also mentioned the gear was designed to be flipped around like this. He also had built an Avid Flyer.

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Posted (edited)

As I'm not only a non-believer but also a friend of Bryce (it is him and his plane in the video) so I sent him a mail. It will be interesting to get his view on this. He is a good pilot with a lot of experience. It will also be interesting to hear why he later changed the returned nose gear main to a real taildragger main gear:

Bryce.thumb.JPG.c59838702beb3580b45a4a36

You can see the difference in geometry.

Edited by FredStork
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Posted

 When I first got my Mark IV it had the tricycle gear on it.  I flew it like that for about five hours, and then we took the nose gear off and swap the mains back around. And by that I mean the left main way up to the right name and The right Maine went to the left and they were rotated 180°. I flew that off of pavement for about another 15 hours, before I moved it out to my grass strip.  I did also move my battery to the back of the airplane from behind The seat. So at that point my CG was pretty rearward somewhere in the neighborhood of 14 inches aft.  My airplane was never in danger of tipping over on it’s nose, mostly because the brakes on it suck! And that is with some modification to the brakes to improve them. I still could not get detailed it come up off the ground with a full power right up. In Fred‘s video where you see me flying there is a set of what I believe are avid c Taildragger gear.  With the tricycle gear on the airplane in the Tail Drager configuration the airplanes sets real flat so you don’t get up off the ground very quickly. I bought that the current gear legs to get the prop further up off the ground. And also I think it looks better.  My experience of using the tricycle gear legs in the  tail Drager configuration for about 40 hours is that it is completely doable, but it just looks awkward. Bryce

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Posted

 When I first got my Mark IV it had the tricycle gear on it.  I flew it like that for about five hours, and then we took the nose gear off and swap the mains back around. And by that I mean the left main way up to the right name and The right Maine went to the left and they were rotated 180°. I flew that off of pavement for about another 15 hours, before I moved it out to my grass strip.  I did also move my battery to the back of the airplane from behind The seat. So at that point my CG was pretty rearward somewhere in the neighborhood of 14 inches aft.  My airplane was never in danger of tipping over on it’s nose, mostly because the brakes on it suck! And that is with some modification to the brakes to improve them. I still could not get detailed it come up off the ground with a full power right up. In Fred‘s video where you see me flying there is a set of what I believe are avid c Taildragger gear.  With the tricycle gear on the airplane in the Tail Drager configuration the airplanes sets real flat so you don’t get up off the ground very quickly. I bought that the current gear legs to get the prop further up off the ground. And also I think it looks better.  My experience of using the tricycle gear legs in the  tail Drager configuration for about 40 hours is that it is completely doable, but it just looks awkward. Bryce

Thanks Bryce,

...but to quote you," it is completely doable" as long as " the brakes on it suck!" and the CG "pretty rearward". It does not really sound like a recipe for success...
 

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Posted

It kind of sits like a Champ ..

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Posted

Bryce's comments make perfect sense to me; if you extend the mains your increasing the angle of attack as it sits on the ground and the added air flow under the wings helps it get air born quicker. We played around with swapping out different wheel sizes on our ultralights back in the early 80's and noticed the same thing. I had an original design airplane that I built based on the Mach .007 plans; at one point I had the gear so low that I could not get off the ground at all. When we switched to the taller bicycle wheels like I had on my Teratorn taildragger the airplane finally could get off the ground. We also experimented on Rotec Rally's and noticed they also got off the ground faster with taller wheels up front. At the time my friend had bought out a dealer's remaining stock of Rally parts so we had lots of tubing and parts to play with. We ended up building a Rally 2b, a Rally 3 and a Rally Sport out of those spare parts and experimented with many different tires and rims. Flying those tail draggers without brakes wore out many tires from all the crosswind landings, those bicycle tires were never designed for the weight and side loads those ultralights were putting on them. My friend also was a bicycle mechanic and we had tons of spare bicycle parts to pick from. We quickly found out those plastic mag style motocross bike rims held up the best but heavy side loads would tear the centers of the hubs out on those too. We also wore out tennis shoes as those were the only brakes we had on the paved runway back in those days. Be careful if trying this with a Rotec as too much tennis shoe pressure on pavement will result in your feet getting dragged under your seat and the the axle. My friend was slow to learn this and suffered many twisted ankles. I learned to skid off the pavement into the grass resulted in burning off airspeed much quicker and saved on tennis shoes and ankle injuries. If the grass had not been mowed in awhile the change from runway to grass tried to put you on the nose. Full up elevator works to keep you from nosing over until your below a certain speed where the tail surfaces don't have enough air to provide any authority. At that point you better be pointing towards something friendly rather than a fence because your at the mercy of the aircraft until it's slow enough to stop. We even tried heavy leather gloves to use as differential brakes during these transitions from lack of  tail control speed to safe taxi speed. By grabbing one or the other tires you could keep yourself from a ground loop. The ultralights would weather vane from a cross wind puff of side air sending you either into a ground loop or try to send you off into a runway fence on the side of the strip.

Later ultralights I flew such as the Fisher 202 still had no brakes but handled well with the smaller tires they were designed for. You might say the Avid Flyer was a copy of the Fisher 202 since the 202 predated the Avid by a year or so. The 202 was itself a copy of the early airplanes such as the Cub, the Aeronca and the Tailorcraft.

That nose wheel skid idea idea I mentioned earlier was not a random thought but a reflection of my vast experience with early ultralights. The Teratorn the Rally and the Mach .007 all started as conventional gear aircraft. They all would nose over if given a chance and they all had part of the frame that would act as a skid prior to nosing over and in most cases it would burn off enough energy to prevent a roll over. The Teratorn and Rally designs were pushers so no danger of a prop strike in a nose over. The Mach .007 was a tractor design but I never got it close to hitting the ground, the frame would drag first in tall grass or a tall clover field slowing you down. My friend did manage to put one of the Rally's on the nose but it took a crash to do it. He ground off a section of the wood floor board before it went over; he was really moving and it was 100 percent pilot error. I've seen first hand the benefits of part of your frame acting as a skid to prevent nose over and the advantages of pushers with their props protected in the back.

My grandfather was a Great Lakes dealer back in the early days of aviation. As a child he would tell me stories of flying those. He started flying in a Jenny.The idea of a tail skid seemed so strange to me at the time. I could not understand why they didn't have a wheel back there. He would tell me stories of holding the stick ahead with a heavy foot on the rudder pedal and then giving it a blast of throttle to turn it on the ground. It seemed so strange until I started flying ultralights a decade later and realized he needed the air over the tail to get it to turn and he needed that tail skid to stop. Those early stories all clicked when I started flying ultralights.

The Cobra the Quicksilver and the Mitchell Wing I flew later all had nose wheels and put an end to the tail draggers and their tendencies. My A-10 Mitchell Wing and later my T-10 Mitchell Wings even had a brake! What progress.

Today it seems we forget there's nothing new here, people have unraveled the tail dragger mystery again and again. Every airplane design has strengths and weaknesses. Landing gear placement has been argued to death since the Wright Brothers and that's a good thing. It keeps things fresh for the next generation learning to fly these things with wings. Is there a magic formula for figuring out wheel placement in regards to wing leading edge or center of gravity? I wish things were that black and white but the reality is more gray. Toe in, toe out, gear forward or backward, angle of attack and more all play into the equation. Another question is who designed the Avid gear so that it could be flipped around and mounted both ways? Clearly the designer intended it to fly both ways right? Is this in the early plans somewhere? The nose gear flipped for tail dragger operation puts the placement very close to the Fisher 202 placement that predated the Avid Flyer. The 202 I flew was quick to raise the tail with a little throttle but I thought it flew great set up like that.

Maybe Bryce has some insight as to where he heard about flipping the gear around? We are hundreds of miles apart so I doubt we heard about it from the same person.

I'm looking forward to hearing other ideas on this subject.

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Posted (edited)

I"Another question is who designed the Avid gear so that it could be flipped around and mounted both ways? Clearly the designer intended it to fly both ways right?"

We know very well who designed the landing gear but the way you are asking implies that you already have the answer to the second part of your question. One could get the impression you are trying to prove that flying with wrong gear is right...

I don't think there was any intention that it should be used both ways. Seen the thoughts put into the the design of the Avid Flyer there would not be different designs of the main gear for nose and tail dragger models it it was intended to be used that way. A more likely reason is that when half of the gear is identical you can save a lot of effort in both design and construction. You can use on welding jig with 2 different wheel axis positions rather than having 2 compleatly different sets of jigs.

It is not be always by design that the round peg fit into the square hole...

Edited by FredStork

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Posted

Are there any plans available for the various landing gear legs and changes made over the years? I'd like a chance to study them.

And before your so quick to pass judgement on Bryce's decision to relocate the battery in the tail; removal of the nose gear assembly had to be addressed since it weighs more than the tail wheel he added in the back and it's also a fact that most Avid aircraft end up nose heavy. The placard in mine reads 433 pounds, how heavy is yours Fred? Most of the things people add for personal tastes get mounted up on the firewall or forward and explains why they end up nose heavy. Even things like brakes, longer legged mains and bigger tires help to make them nose heavy. The center of lift on a straight wing is usually somewhere from a 1/4 to 1/3rd of the chord of the wing when the airplane is level. Most tail dragger designs put the mains close to the leading edge of the wing which is ahead of the center of lift. The center of gravity location is also ahead of the center of lift. Adding weight ahead of the center of lift requires either weight in the tail to balance the addition or a higher angle of attack. Those that chose to go with the higher angle of attack to make up for the additional weight up front will suffer slower speeds and reduced climb rates due to the added drag from the increased angle of attack.

 

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Posted

I think that who ever stamped 433 lbs on your placard was using poor scales or just not being truthful.  My B model Avid had a 532, rope start, no battery, light wood prop, and it was 445.  My first Avid which was a rebuilt A model, and had electric start was 525.  Both of my Avid MK IVs came in at 585 lbs when they had 582s with electric start.  All of those planes were taildraggers.   JImChuk

PS  My first Avid MK IV was stamped 460 on the placard.  I think the builder copied the sample W&B sheet in the manual for that weight cause the plane was 125 lbs heavier

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Posted

 I built a kit fox 2, end it came in at about 420 to 430

Dean,s orginial #99, that Paul Seahafer owner 370,nose digger 

 My first avid, serial number 82, a model A, came in @378 cyauna powered,converted to532=395!

 Butyrate dope, 2coat silver on top surfaces only  minimal white topcoat, pull start, wheel barrel tires, drum brakes, sling seat

 Minimal instruments! And the list goes on to prevent  ANY under undesirable weight, it can be done,

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Posted

Cloud Dancer,

I think you are misreading me. Why would I judge negaitive the decision of using what ever is at hand to adjust the CG? Ask anyone using a 912 or Sob and you will find that most of them have the battery in the tail. This is perfectly normal and I have no contradictory opinion. But having the CG "pretty rearward" to avoid tipping over is something compleatly different. 
However, if you do put your battery in the tail, make sure it can't not get lose in a crash as it will make a really nasty projectile aiming for your head or spine... 

Pilot and passenger CG is 16 in aft of datum, i.e very close to the aft limit and any luggage way behind. So starting "pretty rearward" is a bad starting point.

Here are the designer notes on CG from the builder manual:

image.thumb.jpeg.0364b9cfebb351d4e07a6ecWeight, unless in the wrong place, is obviously unrelated to CG but as you ask.. in the paperwork for my plane there is a "reference empty weight", I don't have it accessible but it is something ridiculous like 400lbs. It must be for the rubber band engine version. My actual (and declared) empty weight is 573 lbs and that appear to be fairly normal compared to others. As I don't need additional weight in the tail I'm using a lithium-ion battery, a great weight saver. 

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Posted

Fred, maybe you missed the video where Bryce was also adding weight to the tail even with the white colored landing gear featured in your photo above? In the video he clearly states his intent is to alter performance to get it to stall more like a Cessna. Nowhere has he mentioned it was to prevent nose over. Link to the video  here: https://www.youtube.com/watch?v=jNVj_I_J5BY

Yes, I have previously read the designer notes you included in your last post. My 2 cents on that topic maybe belongs in a new thread but here goes. Being a machinist for many years I'm used to working with tolerances. Something to be made with a diameter of .995 to 1.005 is usually written as 1.000 +/-.005 or 1 inch plus or minus 5 thousandths of an inch. A 1.000 inch diameter part is what I would try to machine. To get to the sweet spot of your CG you also need to find the middle. 16.5 max minus 11.185 minimum is 5.315 and that number divided by 2 is 2.6575. That's your minimum and maximum deviance number when your CG is set in the middle. 11.185 plus 2.26575 is 13.8425 and that's very close to the 14 inches aft that Bryce mentioned in his reply above. I'm not quite sure how you are coming up with Bryce being close to the aft limit when he clearly states he's around 14 inches and that's almost perfect. If you wish I can convert to metric for you. Also keep in mind that there is a safety margin built in the numbers published in the book to keep the airplane stable within general aircraft guidelines. In reality those numbers are more for making the aircraft stall and spin resistant and recoverable in those situations. Since most people these days are not trained anymore in stalls and spins we try to put training wheel numbers in our figures to keep the average pilot safe. Not a bad thing but it can make a sensitive airplane fly like a bus.

Anytime your flying out of spec you are doing test pilot work without the hazard pay. Many groups today still argue over the possibility of flying a Cub solo from the front seat even though many are placarded against it. I mentioned my grandfather was a Great Lakes dealer, he also owned a Stinson and a Waco at some point. As a kid in the 60's I heard him tell me he liked the Champs over the Cubs because you could fly them solo from the front seat. Under some conditions they found the Cub would not recover from a spin. Everybody practiced stalls and spins back in the 30's, it was required to get your license. My point here is too weight ahead of the CG can be just as lethal as too much weight behind the CG. I have no idea how fully the Avid Flyer was tested under extreme ranges of it's recommended CG limits. Your reprint out of one of the manuals only applies to one version of the Avid Flyer with one set of wings and in one landing gear configuration. And even then the rearward limits were not fully tested, it was only tested to 14.562. It states flutter and stalls. One can pull a stall in an airplane that results in a tail slide and progresses into an inverted spin. I doubt those were attempted. Some airplanes that can recover from a stall; cannot recover from an inverted stall. Anything not listed in more details may or may not have ever been tested. Even if it was fully put through the paces during testing; no manufacturer wants the liability that could result from a customer trying something outside of his abilities. Also in your manual reprint the max fuel ever listed is 54 pounds. At 6.3 pounds per gallon that's only about 8-1/2 gallons. Hardly a true test of spins at full stress numbers. Anyone getting into a spin without wanting to is probably going to have more fuel on board.

I'd still like to see measurements comparing the arm length from the datum point of the tricycle gear attached in tail dragger configuration and the original Avid Flyer model A when it was first setup as a tail dragger. Someone in this group from Idaho may want to ask the original designer the next time he bumps into him.

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Posted

Fred, maybe you missed the video where Bryce was also adding weight to the tail even with the white colored landing gear featured in your photo above? In the video he clearly states his intent is to alter performance to get it to stall more like a Cessna.

Cloud,

did you not just answer your own question? I don't think Bryce added weight in the tail when he changed to the tail dragger landing gear, I think he left the weight in place as he might have been satisfied with the stall behaviour as you mention. And if he was happy, why modify the CG by moving the battery? His change of landing gear had very little impact on CG as it only moved the wheel forward about 6 inches (the exact distance to be confirmed). This could be comparable to the passenger stretching, or not, his legs. 

I wish you good luck and many safe flights,

Fred

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Posted

Hey kids this is the experimental world of aviation. That being said no plane is going to be the same no matter what you do . Mine is a true speedwing with a 582 3:1 c box and a 72" warp drive tapered tip. I get 1200 fpm solo and cruise around 120mph. You can have all the same equipment and get very different results. Landing gear being flipped around on avids has been a hot topic since it was designed. I heard about it years before I even got one so it had to come from people who tried and lived to tell the tail. Cg on these is also a hot topic and most are nose heavy and whatever someone does to make it a little more center is there business. I'm definitely not worried abot weight and all that considering I weigh 150lbs and my plane is around 535lbs. It has been put on a diet but I did add a couple things that didn't make anymore nose heavy or tail heavy . Shit I can honestly tell you I didn't weigh it after because the stuff I did was minimal in weight it was all for performance. If how someone sets there plane up and chooses to fly it is going to start bickering don't fly in it and stick to your own plane. I know this will start some mud slinging on my end bit when is everyone going to realise we have these little planes so we can do what we choose with them and use the manual as a guideline ? It's not a certified plane where tou have to stick to the book .... Now go out enjoy your plane and don't worry about someone elses choice. I'll get off my soapbox now and go make some parts for mine and a couple other peoples GOODNIGHT

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Posted

Well said!!!

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Posted

On the other hand, if I was going to do something that might very well mess up my day, and someone showed me a better way, I would be glad they stepped forward, and I avoided a costly repair.  To each his own, I always try to help, and hope it comes across that way.  At this point though, I've said as much as I'm going to on this subject.  JImChuk

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Posted

On the other hand, if I was going to do something that might very well mess up my day, and someone showed me a better way, I would be glad they stepped forward, and I avoided a costly repair.  To each his own, I always try to help, and hope it comes across that way.  At this point though, I've said as much as I'm going to on this subject.  JImChuk

I'm with you Jim but you said it right to each his own ....

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