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Great Gonzo

May 02, 2015



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Great Gonzo

Great Gonzo

Completed September 2001

 
 

Airfield Models (http://www.airfieldmodels.com/)Prototype Specifications and Equipment

Wing Span: 58"
Chord: 10" (11-1/2" w/flaperons)
Wing Area: 580 square inches (667 square inches)
Aspect Ratio: 5.8:1 (5:1)
Weight: 29 ounces (34 ounces)
Wing Loading: 7.2 ounces/sq. ft. (7.3 ounces/sq. ft.)
Length: 42-3/4" from back of propeller to elevator hinge line
Engine: O.S. .15 CV-A
Transmitter: Futaba 8UHP
Receiver: Hitec Micro 555 5-Channel
Battery: 4.8v, 350 mA NiCad
Servos (3): V-Tail (2) and Throttle JR C341
 
 

Great Gonzo Plans

I have received a number of requests for plans for Great Gonzo.  As of this writing (Feb 2004) I am working on them diligently and they are coming along well.  The fuselage drawings are completed and highly detailed.  I still have the wing and V-tail drawings left to do, but they should not take long.

I have spent a lot of time and effort in this design and it has paid off.  The prototype shown here was flown for over two years and underwent multiple changes including replacing the V-Tail three times, changes to incidence and thrust setting as well as testing flap, flaperon and V-Tail only versions.

Great Gonzo is ready for prime time.  My fellow club members are impressed with the design and I have let anyone fly it who wanted to.  I have received nothing but positive feedback.

The design that will be released is the fourth generation and finely tuned.  This version begins with the last version and has a few more changes that I believe will make a good design even better:

Before the plans are released, another prototype will be built to ensure the plans are correct and that nothing has been omitted.

When the plans are released, they will be announced on this page.

 
 

About Great Gonzo

Great Gonzo is my "Zen" airplane.  I call her a Kite with an engine because that is how she flies.  Of all the R/C aircraft I have owned or flown, this one is my favorite by far.  She was designed and built in approximately ten days in early September 2001 and is a direct descendent of Gonzo.

When I fly Great Gonzo 90% of each flight is with the engine idling or a couple clicks above low idle.  That is no exaggeration.  With the CV-A she can climb at about 1,000 feet per minute at full throttle and once at altitude she just floats around on the air currents.  I have also used a Magnum .15 which is significantly less powerful, but still provides plenty of power for the model.

To really enjoy this airplane you have to work with the wind and let the plane do its thing.  I like to keep her nose pointed within a 180 degree arc.  At 90 degrees she is directly into the wind.  To move downwind, I simply turn her slightly away from that heading and let her drift.

She is incredibly relaxing to fly.  I usually grab a drink and a chair and sit back with the transmitter in my lap.  I just bump the stick every once in a while to correct her heading and watch her float around.  You could call it assisted free flight.  Flights of 30 - 40 minutes are routine on a 3 ounce tank.

I have flown this model extensively using only the V-tail, but to prove it, I removed the flaperons and servos.  Control response with only the V-tail is excellent as it has been all along.

The model is now about 3-4 ounces lighter (under two pounds) and it climbs like crazy.  One person even asked me if I had a .46 engine on the plane.  I had to show him the model to prove it was a .15!  Generally people think the model has a .25 on it.

Great GonzoI believe the model would fly well powered by a good .049 or .061, but I have not tried it.  If I did, I would not take her out on windy days for fear she might get downwind and lack the power to return.

A .10 is all she needs and the .15 is more than she needs.  I like the .15 to get her to altitude fast.  With a smaller engine, it will just take a lot longer.

The prototype has several hundred flights and countless hours.  So far the only damage incurred has been due to blowing over on the ground.  That is just a matter of me not being diligent and removing the wing between flights, leaving her unattended on a table or turning her cross-wind during taxiing on exceptionally windy days.

The first flight on December 22, 2002 posted an endurance flight record for this model.  That record was broken on the second flight.  The first flight lasted 47 minutes.  Great Gonzo ran out of fuel at 34 minutes and was dead stick for the remaining 13 minutes.

I am not a good judge of altitude, but I am guessing she was between 1,000 and 1,500 feet when the engine cut off.  Most of the club members present were unable to see her because she was a microscopic dot in the sky.

The second flight lasted 56 minutes.  She went dead stick after 38 minutes and landed 18 minutes later.  She was at roughly the same altitude as the first flight.  I wouldn't know a thermal if it bit me, but apparently I caught some lift to be able to stay aloft for so long.

In fact, at one point she seemed to be gaining altitude and I was seriously concerned about the range of my radio.  In any case, I was impressed enough by these flights to tell you about them.

 
 

Bon Voyage

On April 15, 2003 I was flying Great Gonzo at an extreme altitude.  I couldn't begin to guess what it was, but I would say at least half a mile high - possibly much higher.  At the altitude she was flying all I could tell was her directional heading.  Her shape was imperceptible -  just a very small dot in the sky.

I took my eyes off her for a second to call a buddy over and when I looked back she was gone.  Last seen she was circling in a thermal slowly gaining altitude.  I scanned the sky for about fifteen seconds and realized I was in serious trouble.  My buddy and I couldn't find her and we called over some others.  Within a minute there were five or six of us looking for her.  Nobody was able to spot her.  I attempted to put her in spiral dives hoping to catch a glint from the covering, but no success.

I live on the west coast of Florida about three miles from the Gulf of Mexico.  The wind was blowing towards the Gulf and I suspect she's out there somewhere.  I have this fantasy that she made it into the Gulf Stream and is on a historic voyage encircling the Earth.

Realistically, I have little hope of ever seeing her again, but if should happen to have any information regarding her whereabouts please contact me.  This incident is without a doubt the most heart-breaking I have experienced within this hobby.  To say I am deeply saddened does not begin to describe my feelings.

Bon Voyage Great Gonzo.

 
 

Construction

To achieve my goals with this model, I needed to design a light but strong airframe.  My philosophy is reflected throughout this design.  The airframe requires solid construction skills because it has only the minimum structure to safely sustain flight.

Great Gonzo with FlaperonsNo shortcuts were taken that would have added weight.  The wing uses the same rib pattern as Gonzo and is generally identical in construction with a few modifications.  The ribs were lightened by removing large sections from them.

Great Gonzo's wing is two bays longer on each panel than Gonzo's wing.  Flaps were also added.  The wing does not have a carry-over spar and is simply joined by fiberglass cloth and slow-cure resin.

The fuselage is truss construction built from 3/16" square longerons ripped from a sheet of light, but rigid balsa.  All the joints in the aft fuselage are reinforced with 1/64" ply gussets.  The longerons run the full length of the fuselage from the firewall to the tail post.

The forward fuselage sides were cut from medium density balsa and no doublers were added.  The firewall was cut from 1/8" plywood and is reinforced by 1/4" triangle stock.  This arrangement is stiff enough even for the powerful O.S. .15 CV-A engine and has shown no signs of deterioration.

Even though Great Gonzo has over forty percent more wing area than Gonzo and two additional servos, she still came in two ounces lighter.  This gives Great Gonzo a wing loading of just over seven ounces per square foot.

 
 

Flying

Great Gonzo has flown over one hundred flights to date with no structural failures of any type.  She is not an aerobatic aircraft, but can loop and roll respectably.  Her rolls are much more axial than was expected.  She can maintain inverted flight although it's a challenge.

The high-lift wing coupled with the model's very light weight combine to make a model that is a slow floater that is capable of flying across the field at a couple feet of altitude cruising at a few miles per hour (definitely less than 10 and probably close to 5 mph).

Great Gonzo with FlapsWith the O.S. engine, she can climb to altitude very fast.  From there I pull the throttle back to idle and watch her float around.  I really enjoy just letting her cruise around the sky doing her own thing.

With a little bit of trim added she will move around the sky in a large circular pattern with very little control correction needed. 

Even at idle, the aircraft takes a very long time to descend.  I have flights logged of over forty-five minutes using only a three ounce tank eventually landing with the engine running.

Lowering the flaps to about forty five degrees is like putting on speed brakes.  She slows down fast and pitches up noticeably.   The pitching has been mostly resolved through mixing flaps and elevator in the transmitter.

When the flaps are deployed Great Gonzo does not want to come down so I usually I raise them before entering a landing pattern.  The flaperons are entirely unnecessary but they are a lot of fun.

As the flaps are lowered the ailerons become proportionately less effective.  However she steers easily using only the V-tail.  At extremely low airspeeds a lot of control input is required and she takes a while to respond.  But when I say "extremely slow," I mean airspeeds (guessing) in the neighborhood of 5-7 MPH.

When throttle is added with the flaps down she climbs at a very steep angle and gains altitude quickly just like a kite.  Most people are surprised when I tell them she's powered by a .15 engine.  They generally think she has a .25.

Two modifications to the design were made after the photos shown here were taken.  The flaps shown have been replaced with full span flaperons that are of the same total area as the original flaps.  I also reduced the elevators to about two-thirds their original area.

I had never built a V-tail model before and wasn't really sure what I was doing.  I did some research but in the end I was guessing.  Unfortunately it ended up with negative incidence causing the nose to pitch up when under full power.  I gradually added down-thrust to the engine eventually reaching minus nine degrees with no significant improvement to the effect.

I am going to have to cut the tail off and reattach it with the proper incidence to correct the problem.  The tail will probably be detached by the time the movers deliver it anyway so that will save me the work of doing it myself.  To be honest it is not a big problem because I mostly fly her at 1/4 throttle or less.  It does not take a lot of power for her to maintain altitude.  The only time I add power is to gain altitude.

 
 

German Modelers

Great Gonzo with Flaps

Great Gonzo shown coming in dead-stick after maneuvering away from a U.S. Army Patriot Missile and surviving to fly another day.

The weekend following September 11, 2001, I went to fly Great Gonzo on an Army post in Mannheim, Germany that is normally deserted on weekends.  I had considered that I might not be allowed to fly because of heightened security.

When I arrived, the post was being patrolled by a guard mount.   I asked if I could fly and they said they did not see a problem with it.

I assembled Great Gonzo, fueled her up, started the engine and range checked my radio.  When I was satisfied that everything was OK, I throttled her up and pointed her into the wind.  Immediately after take off, I climbed her to around 300 feet.

No sooner than I did so, an MP vehicle approached me with flashing lights and a wailing siren.  That was the end of my flying on Army installations.

After leaving the field, I stopped by a hobby shop in Leimen-St. Ilgen, Germany owned by my friend Reiner Pfister.  Like a bartender, he listened to my tale of woe while ringing up my purchase.  He invited me to fly at the local flying field as his guest.  When he closed his shop that afternoon I met him at the field and that is where I flew from then on.

Even though I do not speak German, the guys at the field were very nice and we always found a way to communicate - normally by making engine sounds, waving our arms like idiots and drawing pictures.

Some days there were flyers who could translate.  The club declined my offer to pay dues for the time I would be using their field, but I did help them put up a fence that kept pigs from thrashing the field in the winter.

My most memorable experience with Great Gonzo was a windy day that kept most of the flyers grounded.  Having no fear or common sense, I fired up the engine and proceeded to show off by  flying her out about seventy five yards after take-off and then flying her backward to about thirty feet from the flight line.

I had her hovering at about fifty feet of altitude and then landed her and never changed direction the entire flight.  She just sat there as a spot in the sky which I thought was really cool.  The flight lasted about ten minutes.  The Germans just laughed.  I am not sure if they thought it was cool or thought I was an idiot for thinking it was cool.  I prefer the former case.

At some point in the future, I may scale the design for a .90 size engine.   This would give the aircraft a 120" wingspan approximately.  I think it would be a good platform for aerial photography or other type of payload.

As always, the biggest problem is transporting it once it is built.  I am also considering making a Micro Great Gonzo for electric or .020 power.  It may never happen, but I have put some thought into it and I think it is not only feasible, but it would fly very well.

 
 

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Copyright 2002 Paul K. Johnson