bluebird recent flights

3 May 2022....late afternoon, varying wind

Mainly this was a flight for fun and practice. I had felt some peculiar rolling at tree top level that made me want to check my rudder before flying any more, so I aborted the takeoff and landed in the grass at the end of the runway. Everything looked good on the ground. I scooted (I taxied but only while balanced on the main wheels) downwind on the hard surface runway, and started the flight over. There may be some peculiar turbulence coming off the tree line on these windier days.

Later at high altitude I did some experimental wallowing with the stick held full back and the engine at cruise rpm. Usually the nose would drop slightly, but with very smooth operation I was able to keep the nose up continuously without dropping. In a moderate turn, when the stick is brought full back, there is still a mild nose drop, but then instead of dropping the inside wing (as might be expected) the plane tends to level out as the nose drops. I don't understand this leveling tendency but it is not unwelcome.

I'm always looking for Bluebird improvements. I considered moving the fuel tank higher to avoid fuel line bubbles, but I'm not going to do it because the height is good now for convenient re-fueling. Then I was going to lower the tail skid to make the tail section deeper, allowing the rudder and vertical stabilizer to be the same size as now but a different shape and farther back. However, I then realized that the present shape is just right for raising the tail skid to shoulder level with the nose skid still clear of the ground, so I can wheel the plane around easily, so I don't want to change that. The only change I am looking at right now is to perhaps use some bouncier wheels, as I had on the Bloop biplanes, to make the plane more robust in hard landings on rough fields. These would just be the "fat" BMX bicycle tires and tubes I am using now (after all, aircraft tires do not come with knobby tread and stylish gum sidewalls) but with extreme wide rims (4 inch). The wider rims allow a larger internal volume for a given tire pressure, thus more bounce.

18 April 2022, late afternoon, smooth winds

There above is the day's photo, showing the Bluebird as it is after more than a year of flying. There are 30 hours on the engine (recorded and displayed by the tachometer), so perhaps I flew 45 minutes a week, except for some intervals of modification and bad weather. Engine operation has been good, without any reworks or adjustments, so I'll just keep flying with it until I see a problem, such as not reaching full speed, abnormal noises, or something like that. Today I did a touch and go on the paved runway, then a landing on the dirt (shown above). Both landings were preceded by a prolonged engine idle, so the windmilling propeller could drag me down on a steep approach. I wanted to practice dealing with landings at the full rate of descent of the approach.

On the first touch down, the flare was ineffective and did not do much to reduce the high descent rate, so I hit hard (I could feel the tires going down on the rims) and bounced a little. This was a good landing, I could have approached over obstacles and then stopped after a minimal ground roll if I had to. Soft landings are for airshows, a serious landing gets the plane down promptly. My landing flare usually reaches full back stick at the very end, a few feet off the ground, but the airspeed can be so low that the plane just keeps sinking fast.

The second touch down, on the dirt, seemed softer, I may have dived a little more and had more airspeed. My runway alignment was not very good, I rolled my left wheel right through a big squirrel crater (in the photo above, a couple of meters behind the rudder), but the ground speed was really slow so it was just another big bump. These flights were fun and interesting, so I'll do more like them, but in response to high landing loads I may need to consider bouncier wheels and a strengthened airframe.

Other items: my EGT gage has stopped working. It's reading zero all the time, whereas it used to read about 800 deg. F in flight.

18 March 2022....late afternoon, slight winds

I took this photo to illustrate how yawing produces banking. Suppose the rudder is yawing the plane to the left (which it regrettably is not in the photo). Now the direction from which the photo is taken is about the same as the airflow direction of the incoming air. The bottom of the right wing is seen, but not the bottom of the left wing, so the right wing is at a higher angle of attack and creates more lift, banking the plane to the left (the desired result). Most airplanes have this yaw/roll coupling to make the flying easier, allowing the rudder to contribute to the banking of the wing. The Bluebird uses a big yaw/roll coupling and a big rudder to do without the ailerons altogether.

Ailerons and roll coupling perform the same primary mechanical function, they increase the angle of attack of one wing and decrease the angle of attack of the other, producing a roll in the direction of the turn.

On the underside of the near wing the view of the shaded area tapers as you look farther outboard. This is because the wing really is twisting so as to slightly lower the leading edge at the wing tip. This built-in "washout" is intended to produce forgiving flight characteristics at very low speeds, near a stall or spin entry. The idea is that the wing center should stall first while the wing tip, at a lower angle of attack, keeps flying. The stall should be milder because less of the wing is involved, and the plane will remain level because neither wing tip stalled first and created a roll.
This is conventional wisdom and is well known, the point is that a designer should not allow an increased angle of attack at the wing tip.

14 March 2022....late afternoon, mild winds

I'm making some continuous turns that are steeper (more bank) and tighter (lower airspeed) than usual, improving my skills for demanding situations. It's a lot like thermalling, except we don't get many real thermals this close to the ocean.

My little engine does not have much kick, it's not a rocket like some of the other paramotor engines. It spools up slowly and the thrust changes are mild. If I feel a thump the most likely thing is that I just spiraled down through my own wake turbulence.

Today, however, in the landing pattern when I throttled up from full drag (idle engine with the prop disengaged and windmilling) to substantial power, going from a dragging prop to a thrusting prop, I felt a shove big enough shove to know that the engine was still there. Usually in the landing pattern, when power is added to extend glide or to climb quickly, you can readily see the effect against the nearby terrain, but it's not something you feel through the seat.

Near touchdown, I'm still tempted to look at the close ground and make small, fast corrections with the foot pedals, but the whole thing is almost always more stable when I just look ahead to the far end of the runway and ignore the local effects. Could it be that a full field of vision makes landings harder? The video below gives a pretty good idea of what good vision looks like on a landing. Maybe open views are exhilarating but erode pilot performance and confidence. Maybe the people who design roller coasters already know this.

13 February 2022....warm & calm

Here I am in the office, smacking it down on the hard surface runway!

This is actually a pretty normal "touch and go", a landing and ground roll, followed by another take off and flight, just an exercise for fun and practice.
Notice that I'm looking at the far end of the runway, not down, which makes for a smooth approach. There is a slight crosswind from the left, I drift a little right then roll back on the wheels to the center of the runway before the lift off. The elevator control stick is slightly forward on approach, then brought back for the touchdown, then forward again for the ground roll, then finally back a little for climb.
The touchdown bump (you can hear it) is a result of a slow landing where the plane has entered the parachute mode and has a high rate of descent to the ground. Watch the elevator as I impact and you will see that I am trying to smooth it out, to no avail. This is not smooth but it does get you down using minimal runway.
I'd rather do all my landings out on the grass instead of on the hard surface, but the soft field runway is shorter and doing "touch and go" landings from there, under calm conditions with a small engine, can leave me with minimal clearance over the tree tops. If my altitude looked inadequate for safe clearance, I would have to do some extra maneuvering, so sometimes it's just simpler to use the hard runway.

Here's the takeoff from yesterday's video. At the start I'm standing out front while the engine warms up, but the engine is at low power so the plane does not move. I stand in front of the plane during warm up in case it does start to roll away while I am not watching, then it will come up and tag me. This might be another advantage of having the propeller in back. The engine warm up is specified by the engine maker, usually about two or three minutes well above idle and including a run up to full speed. (In the video I edited out the run up, getting in the plane, and the takeoff radio call. My webpage server limits upload file size, so if I want to post a video longer than 30 seconds I will have to use Youtube or Vimeo).
At the very beginning, you can see that the windsock shows almost no wind, and the fuel tank is about half empty. Full throttle is applied for take off, but this engine gains speed slowly, making the ground roll a little longer. Would a really heavy paramotor pilot have to run this far to get in the air? The nose goes down to level for the ground roll, then up a little for climb out, not getting far from level while in flight.
Notice that at the end of the clip the plane has not climbed above the tree tops and will have to continue the takeoff leg until it is high enough to turn left. When I overlook that first gravel taxi way, I have traveled about 500 feet over the ground. I'm using a low powered engine, but otherwise this is an ordinary motorfloater takeoff, with calm air and the engine running well, and moderately sized squirrel holes.

6 February 2022.....late afternoon, light wind

First flight with a helmetcam!

Also I had just re-set the strut lengths so they are all equal, adding about a degree of washout to the outer wing panels, so this was a test flight of modified wing twist as well as a video shoot.

The engine start was prolonged, probably because it had been several weeks since the last flight. I used the primer bulb to pump a lot of gas into the empty fuel line while holding down the carburetor button. I needed the button to open up the line for increased flow, allowing the vapor to be blown through and replaced by liquid. I tried a few start pulls with no success, then advanced the throttle lever and tried a few more. (This I can do safely in my motorfloater because my engine is firmly secured and the propeller is well guarded. Using an advanced throttle (not at idle) for starting a paramotor might be dangerous since a burst of power might move the engine). I was concerned about possible flooding, but it started at last, and I learned more about how gas systems behave when they sit around unused for too long.

12 January 2022.....late afternoon, increasing and turning winds, getting darker

I think this is my first flight in one of my planes where I used a horizontal trim tab, and it was effective without other consequences, a success! The evidence is in the photo, which I was able to take with both hands, without diving (maybe). With San Diego Bay framed inside my struts, I have a good enough horizon for measuring my wing angle at this level cruising speed.

I pasted the photo into my CAD program and measured an angle of attack of 6 to 7 degrees, a lot less than I expected. Maybe my wing is super good at producing lift, or maybe I need to take more photos and be sure I am not descending. This is supposed to be a one speed airplane, always slow, struggling to stay in the air with a pathetic little engine, so I expected a high angle of attack, up in the teens, maybe.

By the time I returned to the airstrip the wind sock was wagging up toward level and the wind direction had shifted north, a turbulent direction in the little valley where I land. I flew a "touch and go" practice landing and takeoff on and off the paved runway, and got mildly rocked around. I had to touch down a little sideways because of the crosswind.

(I sometimes use the paved runway for "touch and go" landings and takeoffs because it is longer than the dirt runway).

My impression of the Bluebird relative to the Bloop biplanes in turbulence is that they are similar in that they get rocked side to side but not much in pitch. I expected the longer wing Bluebird to be rocked more than the biplanes, but it seems to rock less.

My final landing on the unpaved runway was across a significant wind, so just before touchdown I turned a bit into it and rolled across the runway out into the field for a wingspan or two, which works well when you have room to do it.

8 January 2022.....mid day, slight winds, wore a jacket

I made a quick flight, just to get up and around the pattern. I would have done more except I was low on fuel. My procedures looked good: landing was reasonably straight ahead, course equals heading (which is what you get when the cross winds are very light), and when the wheels touched I pushed the nose down to level, raising the tail to the the ground roll "good control" position. I don't recall if I looked at the far end of the runway as I was planning to, but I felt I had done my duty and demonstrated good landing practice this time.

3 January 2022.....late afternoon, slight winds, sunny and warm

In 2022, the Bluebird flies on! I might even be flying better as a result of my frequent, casual flights, often to test minor changes. Today I had modified my stylish retro throttle for almost full throw (full back is idle, full forward is nominal full power except for the stop about 1/8 inch short), and I had checked it out with engine runs on the ground. At last, into the new year with a thundering 16 horsepower, I flew a full ceremony blast off, with throttle all the way forward! It didn't fly any differently, but it was spiritually enhancing.

The camera refused to work in the air (although it worked perfectly on the ground) so no pictures, this time. My camera handling was awkward, I suppose, mostly as a result of having to hold the nose up while aiming, the plane wants to drop its nose when the stick is not held. I tightened the stick trim bungee recently, it worked, but now after only a few flights it seems to have stretched out again. What I want is to have the plane hold a stable, slow speed in level flight, so I can release the elevator control stick without an immediate change in pitch attitude. I'll probably try a trim tab on the elevator next, that might be a simple fix.

My landing was a little sloppy, I tend to regard the landing as just about over when I skim down onto the wheels. I still need to remember to do two things: 1) look at the far end of the runway and 2) put the nose down to level as soon as the wheels are on the ground. Part 1 will help stabilize the plane in yaw, a slightly sideways landing is normal but I tend to make it worse by over- controlling with the rudder. This tendency to over-control is reduced by looking farther ahead. Part 2 means forward stick pressure as soon as the wheels are on the ground, a prompt transition from the normal tail down landing to a nose level (or low) ground roll, which is more stable and allows more effective steering.

21.December.2021...

My after-landing photo today shows the divot in the dirt from my nose wheel stop at the end of the unpaved runway, the result of a normal nose down landing. The non-rotating wheel, actually a nose skid, serves as a ground brake but only acts over a distance of about a meter when used at slow speed.

True confession: my nose wheel is junk and needs a re-design (notice the side tilt in the photo, it wobbles). The current setup is brainless, it was derived from the previous system by switching the rear struts to the front and swinging the wheel back into the frame, where it just happened to fit snugly by accident. The old front struts became the rear struts, and now I had a shorter airplane that fit better in the hangar.

My main wheels are at the center of lift, so I can stop on the nose or tail, I just have to make up my mind while rolling before I slow down so much that I lose pitch authority. If I wait too long, I can still add power to speed up, and then choose which way to stop, as I did on today's ground roll. If I want to stop on the nose, I hold a forward position on the stick to keep the nose a little low, and when I get slow enough the nose will drop and stop. The nose down stop is probably essential for landing a motorfloater in a very strong wind and getting out of the plane safely.

The Bluebird main wheels have no brakes, just as in the early years of airplane flying. I was trying to compare conventional airplane tires to my knobby bicycle wheels, when I realized this was mostly pointless. Modern airplane tires are very much designed for their braking properties on hard runways, which mean little to me.

The knobby main wheel BMX tires may become my tires of choice if they can resist punctures by thorns, which the bicycle literature says they do. I have seen some signs of this, I have already removed thorns from the new tires that were not driven as far into the rubber as they often are with the street treads. Maybe I don't need to put sealant slime in the tubes anymore, that would be a benefit.

Right now I'm applying blue thread locking compound to all my maillons, the quick links I use for nearly all my lines and cable tensioning. These removable links are very practical for line and cable attachment but they tend to unthread themselves under vibration, which could make them the weak point in the cable. I have locked the maillons before with tape or a strong twist with pliers, but the locking compound should be just a good, maybe more reliable and durable. This thread locker is not much used on aircraft, as far as I know, but I'm willing to try it on hardware that is visible on every pre-flight inspection.

Looking at the video below you might see a lower throttle position than expected. I'm at fairly high engine speed (cruising with a very small engine), but the throttle is not advanced very far forward (forward being the increasing power direction). This is an example of design legacy, on my biplanes it was the same, I never bothered to set up the throttle beyond adequate function, full power is barely halfway forward on the lever. I have used the same hardware in the same way on several successive designs, never bothering to set it up as originally intended. Maybe now I'll change it so the full throw gives full power. I don't think this will give me much more precise engine speed control, nor do I have much need for precise control, but I might like it.

16.December.2021...

Today I accidentally recorded my first Bluebird inflight video, so here it is, all four seconds of it! I was fumbling around, trying to take still photos with my digital camera, and this is what I got. Prepare for a sound blast, this comes complete with 80cc engine noise at the cruise throttle setting. (When will there be an electric motor with a big, slow turning prop that is not loud? We don't have to wait for better energy storage, the quiet system could be developed now.)

At right below, above the tire, you see one of my new wheel fork assemblies, to keep the fat BMX tires clear of contact with the front landing gear struts. I flew with them but I need to finish the adjustments and fly in calm conditions to really judge the stability of this setup. These knobby tires may be a mistake if they are less stable than the much smoother street tires.

There was a lot of wind effect today. The downwind nudge at liftoff was exactly what I didn't need while trying to evaluate a new wheel setup. All three landing approaches (two were touch and go practice) involved intermittent crosswinds, so I would sometimes be touching down in the middle of a drift correction, one wheel low at a bank angle, a "wheel dance" landing, again not very useful for testing the landing gear.

I'm taking off toward a row of trees at my airport. The headwind produces a big sink hole in the middle half of my takeoff leg, but there is usually big lift on the upwind side to make up for it. This is kind of a test of faith with my little engine, I sometimes lose all my takeoff climb and have to wait for a boost to get high enough to cross over the trees. This is a motorfloater, so if necessary I can just turn back and circle up to get over an obstacle, but in the takeoff pattern I prefer not to deviate from what is expected unless I have to. Today was a good sink and lift day, no problems.

Turning from upwind to downwind is visually dramatic at low altitude in a slow flying airplane. A steady wind has no actual effect on the flight of the plane, you are turning normally, but you see the ground sliding away to the side as it might in some horrendous side skid. I saw this again today, and I can understand once again why the temptation to react is strong. My airplane's attitude looked normal, so I just sat there and let it turn until the visuals got less extreme.

Some later changes from what is shown in the video and photos: the red throttle knob is now black (an aircraft recommended standard for combustion mass flow) and the red tape on the maillons (quick links) is gone, replaced by the use of thread locking compound (not an aircraft standard).

12.December.2021.....late afternoon flight

Flying with a small engine is beginning to feel normal. The slow climb rate has not been a problem, just something to get used to and allow for. Maybe this is the way it should be, flying with a minimal engine to reduce fuel handling, engine influence on flight control, noise, and landing distance due to weight.

Near sunset the light was dim, this combined with vibration may be the cause of my fuzzy photos. I took a few pictures but the focus was bad on all of them, so I didn't post any. Also I had some trouble leveling out too high on the landing, coming down with a bounce, which dimness contributed to, I think. Judging height above the nearby ground is more difficult close to sunset.

Tightening the stick trim bungee cord was effective, it held the nose up in flight so I could use both hands for the camera without diving. Trim bungees don't seem to last long before they stretch, maybe I should try a metal spring.

I flew two touch and goes on the hard runway, then landed on the dirt strip, also did my 360's, sharp turns, and roll reversals. I may try some S turning on the takeoff leg to get more time to get high over the trees, but this is probably not going to be worth the effort and disruption. In the pattern it's usually better to do what people expect you to do, even when you think you are all alone.

28.November.2021......just before sunset

Calm and warm, still flying in shorts and a jacket. Take off was delayed a little while by golf carts and people doing field maintenance, also by paragliders coming over from the local soaring ridge to land on the airport grass (grass is unusual for a California landing). I was amused to note that they mostly acted as if there was no traffic. Even at the runway threshold in the plane with my engine running I am still invisible. In other words, as airfield traffic goes, I count as zero. This is somewhat realistic, since my operations usually are very slow and predictable, taking up very little ground space. However, I waited until the entire field was clear before taking off, because if things had gone wrong I might have needed extra room.

I floated around, taking pictures while banked left and right to get a good measurement of my "usual" turning bank angle (wingtip visually on the horizon). The measurement method is similar to looking at the pilot's view photo below where I see the rudder tube at an angle of about 21 degrees to the (poorly defined) horizon, indicating a 21 degree bank.
Previously I thought it was turning at about 25 degrees, but now I am measuring 18 degrees.

Typically, if I have good altitude and I want to briefly tighten a turn, I just pull the nose up, like an RC model with aileron turn control.

In the walk away photo, after landing, the stuff I wear flying is piled in the seat. This is unphotogenic but realistic.

Maintenance List: there is still a light intermittent wheel rub against one landing gear strut, that needs adjustment. The flip down cover on the engine run switch is hanging up before the switch is opened (off), needs lubrication. The pitch trim seems a little nose down in flight, I'll tighten the stick bungee (in photo: light colored line from stick bottom forward to nose).

In the photo notice that the right rudder pedal is back and the control line is drooping below the tail boom. The bungee cord rudder pedal return needs attention.

12.November.2021....about an hour before sunset

There's nothing much to test on this flight, it's just for fun.

Looking down at my new stylish wheel, I am gaining confidence that it will do its job and let me set down at some side angle while bouncing on through the squirrel holes. I still doubt that the knobby tread is good for anything but show and spurious drag on an airplane, but I suppose there's always room for some nonsense. I haven't tried these tires on the pavement yet.

As you can see below, it's still warm enough for shorts and toe sandals. The Pacific Ocean is out there, hidden in the haze. I was satisfied by just poking around the local area.

My landing was the most accurate in a while, even though there was no evident headwind to help out, so I was pleased. On the 500 foot dirt runway I try to land as short as possible, pretending that my airfield is small. Actually I have a big over run if I get sloppy and need it.

Earlier, while driving to the airport, I had stopped for a little fresh gas. As usual I pumped 0.8 gallons into my mixing jug, with a half charge of oil already in it, which will give me the right fuel/oil mix if the station pump is accurate. I shook it up and poured it into the Bluebird tank, and it's good for the next couple of flights, because I'm not using much fuel. I'm making short flights but with a lot of satisfaction.

I'm still self-inflating on my claim of flying the world's most efficient gas powered airplane, a boast so far unchallenged.

	9.November.2021 The photo was taken before the flight. You can see the that gas tank is almost half full, which will keep me up for about an hour, in theory. I would not take off with much less than this. This is the kind of thing you look at during the preflight inspection. New tires! I installed larger bicycle tires for a more elastic landing gear suspension, (and to get the gum colored sidewalls for a new "retro" look). These tires are BMX 20 x 4 (nominal 20 inch diameter, 4 inches wide) with moderate knobby treads, still mounted on the nominal 1.75 inch rims (not a real rim dimension, these wheel rims are sized for a 1.75 inch wide tire). The previous tires were 3 x 20, so this larger set will have a greater internal volume of air, even when mounted on narrow rims. They should be softer and give me more bounce during hard landings. Flying with these tires was ordinary, maybe a little softer on touchdown. I'm glad they didn't pop out of their rims, I'll keep them well inflated as a precaution. During the landing roll out, I could hear one tire rubbing against one of the landing gear struts. I will add an axle spacer to try to make a little more clearance. Now that I think about it, I'm surprised that I could hear the wheel rub with the engine running and my helmet on, maybe it was rubbing during the takeoff too but the sound was lost in the noise of the engine at full power. Slick tires would probably be better, I don't think the tread knobs will do anything but add drag, we shall see. Street slicks are considered stylish by adults, but I think kids want knobs, and these were described as kid's tires. At takeoff the motor took 4 or 5 seconds to come to full power, a real slow response. Maybe this is typical of new engines as they get used. This is usually no problem except when using a short or rough runway, where you might want to get off the ground fast and climb steeply.

9.November.2021

The photo was taken before the flight. You can see the that gas tank is almost half full, which will keep me up for about an hour, in theory. I would not take off with much less than this. This is the kind of thing you look at during the preflight inspection.

New tires! I installed larger bicycle tires for a more elastic landing gear suspension, (and to get the gum colored sidewalls for a new "retro" look). These tires are BMX 20 x 4 (nominal 20 inch diameter, 4 inches wide) with moderate knobby treads, still mounted on the nominal 1.75 inch rims (not a real rim dimension, these wheel rims are sized for a 1.75 inch wide tire). The previous tires were 3 x 20, so this larger set will have a greater internal volume of air, even when mounted on narrow rims. They should be softer and give me more bounce during hard landings. Flying with these tires was ordinary, maybe a little softer on touchdown. I'm glad they didn't pop out of their rims, I'll keep them well inflated as a precaution.

During the landing roll out, I could hear one tire rubbing against one of the landing gear struts. I will add an axle spacer to try to make a little more clearance. Now that I think about it, I'm surprised that I could hear the wheel rub with the engine running and my helmet on, maybe it was rubbing during the takeoff too but the sound was lost in the noise of the engine at full power.

Slick tires would probably be better, I don't think the tread knobs will do anything but add drag, we shall see. Street slicks are considered stylish by adults, but I think kids want knobs, and these were described as kid's tires.

At takeoff the motor took 4 or 5 seconds to come to full power, a real slow response. Maybe this is typical of new engines as they get used. This is usually no problem except when using a short or rough runway, where you might want to get off the ground fast and climb steeply.

24.October.2021....an hour before sunset

Another sunset flight with mild wind conditions, cross at about 5 mph. but actually quite comfortable. I wore hiking shorts and a puffy jacket. Will this be the last warm flight of the season? Hopefully not.

My new landing gear side struts now have Styrofoam fairings with light spackle for filling, rough and not yet sanded, but with no ill effect in flight. I did notice a left turn tendency, so I will adjust my trim tab on the ground later to neutralize that. This was my first flight in the Bluebird with another ultralight in the traffic pattern, no problems there, we just used our made up names on the radio until we started to agree. I did my circles for turn practice and some extended climbs, which require some patience and some high rpm operation with this little engine. I find myself stopping mostly nose down recently, that is convenient for getting out, as long as the upgraded nose wheel shows no signs of overload (breaking).

I'm trying to practice what I call "numberless flying", not reading any gages at all during the flight. This might be fun, a way to return to a more pure and simple form of flying, similar to the early ultralight airplanes, paramotors, and perhaps some Edwardian aircraft. The engine temperature gage is easy to ignore because it always seems to run cool and read the same, but I do tend to look at the tachometer because I have had the habit of setting the engine speed with a number. I want to control the airplane by looking at what it is doing, without numbers.

26.August.2021.....morning flight

Conditions were calm and warm. I flew in a tee shirt, shorts, and sandals, quite comfortably. At about 200 feet up I passed upward through a thermocline, into a layer of air noticeably warmer than the air below. This was a welcome effect, since I could keep on climbing without any wind chill.

Touring the local area, I checked out objects on the ground and flew some circles for practice. Landing with no headwind at all, I floated far over the ground, finally coming to a stop after using up all of my unpaved runway (actually just a track across a field).

The landing on the nose felt smooth and gentle, but afterwards I noticed that the plastic frame of my nose wheel was shattered to pieces, so this little bicycle wheel is not going to be a durable skid. I'm now using a stronger replacement, still a plastic wheel but with more spokes.

The nose of the plane still wanders around just prior to touch down during the landing, which is often a little sideways. I don't remember the biplanes doing this. Maybe the tail is a little short (referred to as "short coupling"), but the tail volume calculations show a generously conventional vertical tail authority. Maybe the lack of a fuselage is a factor, or maybe just the extreme slow speed at which I finally land. I have read that some pilots of more conventional airplanes prefer to land fast for extra stability rather than use all their flap for minimal airspeed, especially in cross winds.

Also, I'm noticing the "parachute mode" at the slow end of the Bluebird speed range, where the sink rate increases and sets me down on the ground firmly instead of letting me float on and on in ground effect. In the Bloop biplane I would get a good bounce sometimes if I came down at the high sink rate, but that was pretty much suppressed when the vortex generators were added. For now I will not use vortex generators on the Bluebird wing because I like setting down promptly as soon as I am in the ground skimming situation, even if I bounce a little.

Bluebird... Recent Flights

by Mike Sandlin Last Update: 23 August 2022