Monthly Archives: April 2020

26 posts

Chairman’s Corner for April – May 2020

Hey guys,

It’s going on five weeks now since the city shut down the beach areas, and subsequently our flying field. I have had people sending me messages with recommendations for hidden flying sites, and I’ve also had one member tell me he received a $400.00 ticket for flying behind a Target store near I- 805. If you absolutely have to fly, please be careful. I, for one have still been at work, and have been staying home on the weekends – working on an “Apocalypse project”.

Sad news this month as we have had two SEFSD members pass away recently (NON-COVID). Jack Hix was an active member when I first joined the club in 2003. He was heavily involved in the club from the late 90’s to early 2000’s, and his personable attitude is one of the things that brought me back to flying with an AMA club after a 10 year break. I haven’t seen him for a while, but I remember his smile and his friendly influence In the club at that time. Also, John Foster passed away recently. For the last 20 years John has been an institution of training at the club and he was always willing to volunteer his time with new pilots with both an intensive ground school preflight training program, and then hands-on instruction. I know a lot of current pilots who spent time with John Forrester as they were getting their wings. Steve Belknap had a chance to meet John’s son this week as he was in town settling affairs, and will also make some comments in this newsletter. John will be sorely missed!

With the exception of the homeless people using Mission Bay Park during the virus outbreak, there should have been little to no traffic on our site. I am hoping the rain has done its job of smoothing out the runway surface, and that no one has slipped in during the evenings to do donuts in the parking lot. I do expect a problem with weed control on the runway proper upon eventual return.

Just a quick note I’m carrying over from last month: When we do return to the site – we will need your used, but still serviceable lawn furniture, and any decent carpeting that you may have replaced while stuck at home.

Not much else to write about since we haven’t had any events at the club since our initial T-28 race practice day mid March, so instead I’m going to paste a couple of pictures in. I get asked quite often just how I store my airplanes, and what my garage looks like. When I purchased my home the garage was unfinished. I had the chance of hanging the drywall myself and chose to Hang it right to the bottom of the roof joists. The first image is of the open ceiling space after I completed the sheet rock. This gives me quite a large space in the overhead to the peak to mount angle irons with pool noodles zip tied to them from which to hang my planes. If you look at the attached pictures, right now I have 68 planes in the garage from micros all the way up to 40% aircraft. And I can still fit a car in there! If anybody wants more specifics, please feel free to email me.

Here’s to hoping things normalize in May and we can get back to enjoying our great Hobby!


Thanks To Everyone Who Contributed!

When I sent out the request to let me know what you guys are doing on your COVID vacation, I never thought I would get such a tremendous response.  Thank you so much for your stories and pictures.  Never let it be said a modeler does not know how to keep himself occupied.  Below are the articles you sent in during the last couple weeks.  These are your editor’s favorite kinds of things.  I love to share what our members are doing with the readers.  Anything from a picture and a paragraph to full blown build article.  It is all appreciated! – Steve B.

“SEFSD Memories 2019”

(The video above starts 16 minutes from the beginning.  Click on the left end of the status bar to see it from the start.)

Frank Sutton, our intrepid photographer, has put together a beautiful collection of pictures and videos from 2019 for your enjoyment.  He says it best:

“This is the SEFSD 2019 Memories movie, 92 minutes of rocking music, videos and photos covering the flying highlights of the entire 2019 year! We recommend you get your favorite drink and pop some popcorn when you’re ready for that one – and crank your speakers up! Starring in this movie are the Pilots and Planes of Silent Electric Flyers San Diego, and the movie is dedicated to them. We hope that by watching it, the Pilots and their Friends and Families will be able to escape for at least 92 minutes from these uncertain times we’re in now.
  During these uncertain times, we all probably have a lot of spare time on our hands and little entertainment. We certainly can’t go flying! So, it took a national disaster for me to taxi down the runway and get this going, and it is about time too!
  In addition to our San Diego County Dash Cam Spy Channel on YouTube, we have a brand new Channel – Aviator Alex! We already have three short videos and one full-length feature movie ready for your viewing pleasure! Please take a look and give us a “Like” if you like it – and we think you will!
  For the moment, all the videos are with Silent Electric Flyers San Diego and flying via Radio Control (R/C), however, we will soon be adding more videos to include Alex’s adventures flying actual sailplanes a Lake Elsinore Soaring Airfield and Hemet Airport with Cypress Soaring (with a Go Pro camera in the air too!)! I have a lot of photos and videos ready to go, and too much time on my hands!
  Here’s the direct link to the new Aviator Alex YouTube Channel……
  And here’s four videos ready for your viewing pleasure……


Stay tuned, our new YouTube Channel Aviator Alex has just taken off!
Keep your seatbelts on, you ain’t seen nothing yet!”

Our Friend & Fellow Member John Forester

“Remembering John

John was born in London England October 1929.  His father was CS Forester, an author who wrote many books but was known for the Horatio Hornblower series and the African Queen

John served in the Navy for a short term before being honorably discharged.  He earned a Master of Science in 1964

He had three passions in life: Cycling, Taking pictures, and Flying model airplanes.

Cycling was not only a passion but a way of life for him. He started to ride in 1937 in England and then continue when they moved to California in 1940.  He was instrumental for helping to fight the battle against mandatory bike paths in 1972.

I remember him as always building and tinkering.  We made model boats and rubber band launched gliders out of balsa wood and tissue paper which would slowly circle before landing.  He also had several rubber band power planes.  I think it really changed for him with the advances in battery technology and then finally from analog to digital controls.  We would often talk about the issues with the analog controls.  He loved to fly and also to teach in his own style and was never afraid to give suggestions and guidance at the field.  He typically liked to fly on weekdays when it was less crowded so that on weekends other could fly.”  – Geoffrey Forester


I was happy when John come and sat with Alice, Sean & I at a table in the back of the room at the Harbor House this last January.  Little did I know that was the last time I would see him.  I heard from him a few days before he died.  We exchanged a couple emails where he asked if I thought someone from the club, who lived near him, might consider helping him if he needed it.  That was our last conversation.

During the dinner he showed me the response he had written to the FAA regarding their proposed new rules.  Well written, concise and to the point.  I was impressed how well written it was.  I just learned that John has been writing professionally for a long time.  He wrote Practical Cycling which is now in its seventh printing.  

John was a big contributor to our club.  He headed up the flight training program and many of today’s pilots learned to fly under his tutelage.  Maybe you have read his comprehensive article on learning to fly.

I received an email from his son Geoffrey a few days ago telling me he had passed in his home.  John was 90 years old.  – Steve B.


“I remember John Forrester as a kind gentleman and an avid competitor in our EMAC competition series. John rarely missed a chance to improve/demonstrate his flying skills in the BASIC class even though he probably surmised that just taking home his airplane in one piece was a successful endeavor! More recently, John’s reasoned and impassioned letters to the FAA defending our rights to fly our models without restrictions, registrations, etc. became the model for mine and other peoples’ writings on the subject. We’ll miss your charm and wit, John. Hope your skies above are filled with light to no winds, perfectly axial rolls and all 10 point round loops”.  – Steve Manganelli


“John Forester (1929 – 4/2020)

When I first contemplated joining SEFSD, John Forester was one of the members I connected with first.  It turned out that John and I shared a common background as subject matter experts; he consulted about bicycle cases while I worked on accident reconstruction cases.  Once I formally joined SEFSD, it became a weekend ritual for one of us to seek the other out for some good old fashioned flight line chatting.

John was well versed about many topics, but the two I recall the best were aero modeling and bicycling.  John was an engineer and those two fields of interest seemed to suit him to a tee.  Each was a science-based endeavor that clearly kept his mind active and heart young.  I think he was 83 when I met him and, irrespective of age, he was a remarkably good pilot. He even remained an SEFSD Flight Instructor until the last year or two.

I had earned his confidence, along the way, and he occasionally spoke with me about his active consulting cases.  I felt honored that he confided in me as a case-related sounding board and I enjoyed the time we shared together.

John’s influence can still be felt today since he was a staunch advocate for the bicycle transportation industry.  I’m convinced that bicyclists today owe a certain debt of gratitude to John and that many policies were advanced by him.

I’ll remember John Forester as a kind and intelligent person who will, no doubt, be missed.  Rest in Peace, my friend.

Eric Shapiro


Farewell to SEFSD Member Jack Hix

“Dearest friends of Jack,

My name is Sara, and I am Jack’s daughter. This post is to let you all know that, early Easter morning, my Dad passed away peacefully in his sleep. He had been receiving absolutely wonderful care for the past nine days from the staff at Day Break Retirement Villa and Seasons Hospice & Palliative Care. Everyone involved with both these organizations was so skilled at helping us navigate this difficult time under such extraordinary circumstances. We never imagined we would be saying goodbye to him over video chat, but the universe does what it does, and you just have to roll with the punches. I will be forever grateful to the staff at Day Break and Seasons. They made this confluence of events as easy as it could possibly have been considering this previously unfathomable scenario. They are truly gifted care providers, for both patient and family. Though we were not by his side, they were able to provide enough connection to make us feel that, in a way, we were there. From the bottom of my heart, I thank them.

My mom, Mary, has moved in with my brother, Jesse, and sister-in-law, Laura Mae, in Richmond, CA. The three of them are enjoying each other’s company and sharing this experience together with deep love and gratitude for our cherished family. My husband, Joel, and I are able to video chat with them several times a day and, for that, we are thankful. I await the moment when we can all wrap our arms around each other again. There will be tears that day.

Once the shelter in place order is lifted, the five of us will be having a memorial service and burial of his ashes which we will live stream here. I will make sure to provide updates as to when that will be taking place. I know how dearly loved my dad was by so many of you. I know you all treasured the amazing, funny, kind, and endlessly brilliant person he was. Please feel free to comment on this post with any pictures of him you’d like to share or stories you’d like to tell about him. Don’t spare the details. Go on at length. Make us laugh like he would have. Since social media is all we have right now, let’s make good use of it. My love to you all. I know my Dad is at peace, and I hope we can use the connections we make here to bring some peace to each other.

-@Sara Jane Hix”


We lost a great club member recently, Jack Hix.  Most of the current members may have never met Jack, but you would remember if you had.  He has not flown much in the last 10 years or so.  Jack was an outstanding modeler and great story teller.  Always quick with a joke and had a tremendous sense of humor.  I think that is what I’ll miss most about him.  I remember him coming out to the field so pleased with his latest creation and ready to show it off.  His attention to detail was inspiring.  Some of his models are shown below like his Mini-Mamba, Old Timer, etc. 

For those members who were around then, Jack provided his expertise as a graphic designer to create the wonderful logos for our yearly events such as the Mid-Winter Electrics, Spring Fling or Fall Fun Fest.  Some of his designs are below.

I can still hear his laughter. – Steve B.


“As for Jack Hix in addition to him being a most excellent modeler and builder of miniature airplanes it he was also the the leading pool shark of, I think he lives in Vista, but the local senior center he regularly clean them out of a couple hundred dollars a night just shooting pool with them.” – Wayne W.


Still Grounded

I know, with self-quarantines, city park closures and this cold wet weather, it feels like we will never get our airplanes off the ground.

But take heart, these drastic measures enacted, seem to be having the intended effect. Infection rates of the virus in San Diego appear to be leveling off. So hang in there everyone and stay healthy.

If you haven’t done this already, drain all your batteries to the storage voltage (3.8 V/cell). Check your aircraft for any repairs needed and maybe start a kit airplane. The Electroglide, T-28 racing and general flying will start up again.


Jeff Struthers

Treasurer’s Report for April 2020

Business is still getting done at SEFSD even with Covid-19. First off, I want to thank the members that continued to join our club even after the city closed the parks in in Mission Bay. All of your support is appreciated! We are at 253 members. As of April 23rd, we are still closed, but look for reopening announcements. Just FYI, we have temporarily suspended service on the port-a-potty until the field reopens, so if for some reason you go there (which you should not) and notice a lack of service, that’s the reason. When we do reopen, we plan to do maintenance on both the runway, and the parking lot. We’ll have 50 – 60 gallons of dust control to soak the entire field and parking lot to get everything in good shape again. Our charter has been renewed, as well as our insurance policy for the city. We’re still waiting to hear back from the AMA to see if we got any money from the Flying Site Improvement Grant. 


Who Needs a Stinking Runway?

Bob Stinson here. Many of you have seen some of my unusual aircraft at the field. Words like “crazy”, “what the heck is that?”, and my favorite “of course you’d have one, Bob”, have been heard often over the years. Well, there was a method to my madness! What would I do if the field was closed down? Vertical flight was the answer. Of course, I wasn’t expecting the culprit to be a virus.

I’m fortunate to live on a cul-de-sac, and on the edge of a canyon. I’ll fly drones over the canyon and helis over both. Happily, neighbors are tolerant of my toys!

Stay safe and healthy everyone. See you all when this is over.

Mark Davis’ Avanti XS Jet Project

I’m using quarantine to work on a Sebart Avanti XS.  It has a 120mm fan running on 12S.  The fuse is fiberglass, the wings are wood, and it has a wingspan of 1.8m.  For comparison, the plane in my hand is the Freewing foam Avanti S (wingspan 1236mm) that many of us have.  I chose a carbon-fiber 17-blade fan (optimized more for thrust than for top speed). – Mark Davis

Allan Flowers’ FW-190

Hi, Fellow COVID Exiles.

Since I can not fly at either the electric field or the Chula Vista club, I have spent time on a new foamy from Motion RC. This is a FlightLine FW-190 44” model, a bit smaller than I like (due to my old eyes). The model is a reboot of an older design which now has added flaps – but not the proper “scale” split flaps : ( I guess the days when I would spend 1500 hours on an over-the-top scale project are probably over anyway.)

This plane runs on a four-cell, which is one of the reasons I got it, since I have several batteries that can be used in it. The battery bay is extremely tight and required some surgery to get everything in. The model is spectacular in detail and fairly good in terms of scale fidelity. I did it in the optional Heinz Bar #13 scheme, adding my own Photoshopped swastika which was missing on the tail (PC reigns). I decided to try some weathering which I have really never done before. My attempt is terrible compared to the incredible models I see on the internet – but I had fun and it isn’t too bad after all. A little black to hit the panel lines, ocher for oil leaks and where the guns dirty the wing, and blotched silver to look like chipped paint on metal…  Everything on the model has been coated with some acrylic floor finish, which pulls it together – as well as sealing down the stickers which, on this model, were not good. The colors and detail was great but they really didn’t stick very well at all – especially the small/thin ones.

Today was spent binding the new RX and setting the throws, etc. Hopefully I will be able to handle this fast little plane, once the field is open again.

I hope all is well with all of you,

Otto’s Nostalgic Builds

Well as soon as the confinement to quarters hit I pulled out two projects to complete. 
The first is Jim Kirkland’s 1970 Nats pattern winning A-6 Intruder. This was built from and old Skyglass kit produced in 1972 that I found in a storage bin. The major issue was the fiberglass fuse. It had been on its side for 35 years and had deformed. I cut it all up and built a jig to reassemble. Turned out pretty well but probably would have been easier to scratch building a new one.
The second project completed Is a ModelTech ARC Calypso. Hanno Prettner’s Calypso won the 1984 International F3A pattern competition. The kit was my first ARC, almost ready to cover, and went together very easily. Very pleased with the results.
Both projects have retract gear and are electric conversions. You should see them at the field tearing up the sky. – Otto

An MQ-9 Story pt.6 – 3D Missiles & Bombs

A co-worker kindly lent me his Ender 3  3d printer. I have taught myself to use it and am now printing missiles and bombs.  In particular, Hell Fire missiles and GBU -12 Paveway  laser guided smart bombs for my MQ-9 project.  So  am learning new skills and moving the MQ=9 project forward in these difficult times.  I can recommend the Ender 3d printer as a nice and economical beginner’s printer as it is producing a fine product(s). – Bob Kruetzer

What I Did on my Covid-19 Vacation by George Sullivan

Like most everyone I have done some repairs to my airplanes. But here is something a little different. It’s flying related but not an airplane. In a prior life I had a video business where I would record various events and provide DVD’s and/or downloads. For this purpose I purchased a Servocity Pan and Tilt device (picture below). I would mount my video camera on it and using a hand held wired remote I could move the camera both left to right and up and down. – George Sullivan

Taking video of RC aircraft is a pain in the …. I always hoped I could use this device but aiming it was a problem. So the project I have is in 2 phases. The first phase is to convert the controls from the hand held wired controller to a wireless receiver and my Spektrum transmitter. This was surprisingly easier than I expected. I now have a 4 channel receiver mounted on the device and can control the pan and tilt motions using the right stick of my Spektrum transmitter. I will output the video from the camera to either a small monitor or perhaps a pair of goggles. Here is a short video showing the Pan and Tilt mechanism controlled by the Spektrum transmitter. ( )

The second phase is to solve the problem with aiming the camera. My plan is to put a “headtracker” on the output display (monitor or goggles) and input that into my Spektrum transmitter. So at least in theory the camera should point where I’m looking.

The first phase is completed . Phase 2 is waiting on the delivery of the electronics for the headtracker. I hope to get the electronics by 4/15. If all goes well, an update for next months newsletter.

Plenty Happening at “Casa Gagliardi”

Like the rest of us, I’ve been “hunkered down” in my case at Casa Gagliardi trying to keep my brain from going to sleep with way too much TV !  So let’s build something…..First it was the Wanderer Glider that Mike Morgan so graciously laser cut for me as it was my first glider back in ’75 after going to Torrey Pines and watching the action there. I had just been transferred here after Recruiting Duty with the Marine Corps in Indiana (can you say FLAT?)

Wow the cliffs were amazing!….It was fun building something small for a change. It’s Monocote covered and weighs 24 oz RTF. I can only practice drums, vibes & piano so much each day so it was a fun build….Mike was building one also so we shared ideas via the phone & internet. 
Build #2 was to finish my Ziroli SNJ which spans 101″ and is to be powered by a NeuMotors 8019/180 which Steve PROMISED will turn a 22×10 APC @ 8K on 12S….This is probably the 5th one I’ve built, as I raced them in the past at USRA and Unlimited Air Racing events. FiberGlass fuse, foam core wings, which Belknap & I cut, Robart retracts, fabric built-up tail feathers Ultracote covered wings, paint from Home Depot and a sound system courtesy of Mike Morgan. That should keep me busy for a while !!!!!
Semper Fi
Frank Gagliardi

Wayne Walker’s Sailing Adventures

Wayne bought a sail boat in 2018 with the intent of sailing from the East coast down through the Panama Canal and on into the Pacific.  The trip has had some starts and stops due to mechanical issues.  Last year he made it to the South of Florida.  This winter he has finally made it to the US, Virgin Islands.  Here are his latest comments as of April 13th:

“I’m trying to get to the US Virgin Islands after getting chased out of Jamaica and not allowed into Puerto Rico.  Great sailing so far, Wayne

I made it to Saint Thomas island in the US Virgin’s yesterday so all is well.  Things are not bad here at all, everyone’s taking the quarantine business seriously and being being good about it I guess is the best way of saying it.  I’ve got to get a place to haul the boat out and leave it here for the hurricane season so that’s my job for the next week or so.  All is well everything worked out, talk to you later bye-bye”

The prequel to this story can be read on his blog.  His latest entry was on Jun 2019:

Kyosho Hurricane Retract Upgrade

The stock mechanical retracts that came with the Hurricane were underperforming.  I replaced them with the main retracts that normally come with the Freewing Avanti Jet.  They fit pretty well with only moderate fiddling and fussing with the mounts.  One of the great things about these retracts is they are very inexpensive.  Only $50 for the set!

If you are looking for retracts for a project, check out  They sell the retracts for nearly all their models.  You can find all sorts of sizes, configurations and styles.  –  Steve B.

The Freewing Avanti S Power Upgrade, NeuMotor Style

By Steve B.

Last year I bought the Avanti S from  Although this is an excellent jet, I wanted it to go faster.  The modification required replacing the entire fan assembly, the motor and the speed control.  It was all pretty simple to do because al the new parts fit right in where the old ones were.  No foam cutting, just a slight change to the ESC mount.

The test flights went perfectly.  It is significantly faster than the stock setup.  The flights are shorter due to the higher currents.  Unfortunately, I forgot to get video.

In order to get the correct motor and fan, I took the easy route and went to our very own ‘motor master’, Steve Neu of Neutronics and asked him.  If anyone knows how to make airplanes go fast. . . well, you’ve seen him fly, enough said.  Steve created a special wind motor just for this application: NeuMotor inrunner 1412/2D/S/5mm with a Kv of 2400.  In this application the motor is using 2700 Watts.  The stock motor’s Kv was 1900.

The stock fan that comes with the Avanti is plastic and specially made to mount on their outrunner motor that itself mounts from the rear.  The motor and fan are cantilevered off the back of the motor.  Seems crazy but it works.  This fan cannot accept a motor that mounts from the front.  Turns out they have fan housing made of metal and it fits a front mounting inrunner (p/n P0806).  I used the fan housing but the fan that comes with it cannot mount to a standard motor shaft.  So I purchased a Jetfan 80 V3 from eJets in France.  It is made to fit the NeuMotor 5mm shaft.

I bought a Castle Phoenix Edge 130Amp ESC to replace the stock 100 Amp ESC.  Current at full throttle is 135Amps.  The battery is the stock 6S 5000mAh Li-Po.

I’ll take you through a pictorial explanation of the conversion process:


Below you can see how I took off the motor hatch.  The screw eyes made it easy to lift it off (after you remove the screws).  Otherwise it is a pain.

Continue reading

How to Size a Jet Exhaust Cone – Math Method

By Steve B.

I needed to make a small conical shape from a flat piece of plastic.  I had replaced the small jet fan in my Kyosho Jet Vision since the original fan shucked a few blades on takeoff (FOD).  The new fan was bigger so it needed an adapter to fit between the fan and rear half of the exhaust cone.  I could do it with trial and error but I wondered if I could figure out the math and create it in my drawing program, and I did.

The part I made was the amber colored piece between the blue fan and the black tail cone. The fan assembly is pulled forward so you can see the cone. Normally it sits all the way back.


The part before installation.

I’m sure there are any number of places online that have this already figured out, where you can simply input your measurements and voila you get the answer.  I didn’t look.  I wanted to see how it was done.  My only external source was my lovely retired middle school math teacher wife, Alice, who provided some of the basic formulas I had forgotten.  Although, when I had a question, I did have to raise my hand and wait my turn. . .

Remember sitting in Middle School (Junior High) Math class and wondering what you’ll ever use this stuff for?  Well, this is a great example where you can use both Geometry and Algebra.  Sound like fun?

A typical exhaust cone will look something like these.  The long one fits my Avanti jet and the other is for my Jet Vision:

The cone template on the left is for the Avanti and the right one for my Jet Vision as seen above.


My drawings were done in a computer drafting program.  You can also do it by hand using a compass, protractor and straight edge.  You may need to commandeer the dining room table if your workbench is loaded with stuff, like mine.

Using my Avanti jet as an example, I created this drawing.  I know the Avanti does not need a tail cone, I just used it for an example.  The calculations are below:

This shows all the geometry involved. The part we are interested in is the small segment at the right.


This is the segment that gives us our cone template.


This is the math used to create the drawing:

What we know:

   <1 = <2  (Angle 1 = Angle 2)

   R2 = R1 + Lc  (Radius 2 = Radius 1 + Length of Cone).  (R1 & R2 are radii used for the layout above.)

   Arc1 (Arc length 1)  see just below

   Arc2 (Arc length 2)

The arcs lengths are the circumferences of the ends of the cone.  For their radii, just measure the diameters of the fan and outlet and divide by 2.  (ro1 = radius of outlet, rf2 = radius of fan.)  The arc lengths are:

eq. 1   Arc1 = 2π ro1 and Arc2 = 2π rf2

Now all we need to find are <1 & <2 and R1 & R2 in order to create the layout.  We know the relationships between the angles and between the radii.  This gives us only two unknowns.

Now we just need two equations.  Solve for one unknown in one equation, substitute that into the other equation and solve for the other unknown.

eq. 1a   (<1÷360) 2π R1 = Arc1

eq. 1b   (<2÷360) 2π (R1 + Lc) = Arc2

Lets solve for R1 in eq. 1a:


eq. 1c   R1 = Arc1÷(.0175<1)

Substitute that into eq. 1b and we get: 

   (<2/360) 2π (Arc1÷(.0175<1) + Lc) = Arc2

Lets solve for the angles (<1 = <2):

   (.0175<2 (Arc1÷(.0175)<1 + Lc) = Arc2

   Arc1 + .0175<2 Lc = Arc2

eq. 2  <1 = <2 = (Arc2 – Arc1)÷(.0175Lc)

The Arcs and the Cone Length are measured quantities, so substitute them in to find the angle.

Now find R1 by substituting the angle into either eq1c.

eq. 3  R1 = Arc1÷(.0175<1)

Here are the numbers needed to make the drawing above:


ro1 = 35mm, rf2 = 41.5mm

Lc = 365mm


From eq1:  Arc1 = 2π ro1 = 220mm, Arc2 = 2π rf2= 261mm

From eq2:  <1 = <2 = 6.419 Deg

From eq3:  R1 = 1958mm, R2 = R1 + Lc = 1958 + 365 = 2323mm

These highlighted values are what you need to draw your exhaust cone.

How to Size a Jet Exhaust Cone – Layout Method

This method is a bit simpler than the previous method.  It involves little math but may require the same clearing of the dining room table to make the layout.

It was sent in by Bruce Brown, club member, expert aerobatic pilot, retired sheet metal Journeyman and all ’round great guy.  I’ve flown aerobatics with Bruce for many years and when I want to know exactly how a maneuver is suppose to be flown I just watch him, usually followed by “Oh, that’s what it’s supposed to look like. . .”  

Bruce:  “If the cone adapter for the jet exhaust was your project then here’s how I would have done the layout, just as I did at work for 36 years. (Step 1) Draw a vertical centerline, then an outline of the fitting or “side view” of cone, bottom being the big end (D2) and the top (D1) centered above it by the length of the cone.  Then draw lines through the end points of D1 & D2 and extend them upward until they intersect. (Step 2) This is the point (Vertex) to then swing arcs through the same end points of (D1 & D2). Multiply D1 & D2 each x π to get their circumferences, which are also the arc lengths (Arc1 & Arc2).  With a flexible ruler, measure half the circumference (arc length/2) to each side of the centerline along the arcs drawn.  Then from the ends of the arcs, draw lines back to the Vertex. (Step3) You now have the pattern.”
I provided these drawings to help visualize the process.  I added the references in Bruce’s instructions above.  This is the adapter for my Jet Vision mentioned in the previous post.

San Diego Dash Cam

The MAY2020 San Diego County Dash Cam Spy video #25 has been unleashed early to help fight the boredom some may have due to the ongoing COVID-19 Crisis and upside-down uncertain times!  Stay tuned to the very end for some Breaking COVID-19 News, you’ve got to see it to believe it!  – Frank Sutton