I built Endgame as my last PA ship that I would fly till one of us died.  Well, it got murdered in a house fire, so I built Endgame II to take its place.  It flew OK but I have always wanted to try a canard, so I added one and II became Endgame III.  III is an unqualified success but I am still above ground and I have always wanted a twin PA.  I had one of those, I think it was Sterling, P-38's with two Fox 15's.  Ever try and get two Fox 15's to start at the same time?  It was a poor performer but the sound, ah the sound.  Well, after seeing Frank McMillen's twin which I commented on in the Endgame III thread it is official.  What appears to be the first twin canard is on the worktable.  There will be enough changes to give it a new name but it still has the same roots so it will be IV.  Aside from the twin setup it will have a 1" longer nose to give the canard more leverage and get it away from the props.  It will be totally in clean air so it should be even more effective.  One thing I noticed on III was that the large elevator/stab was too far back with the addition of the canard. The elevator became way too sensitive along with the logarithmic.   Great for corners but you have to fly it in-between them too!  So, I am moving it from 19 1/2 to 18 1/4.  I am switching airfoils from the Geo-Bolt to Geo-XL.  I used it on my Trifecta and the thinner wing seem to penetrate better and still have gobs of lift.  The last change I am making is going to inline.  I have no experience with this one so I am relying on those who have gone before to be right when they say that a twin electric should be inline.  I will post drawings/plans when they are finished for any and all to laugh at.  All suggestions will be appreciated.   

Things that I have to decide on include the logarithmic.  III has a tendency to "snap" in a turn.  What I mean is that if I need to increase my turn rate in a round just a little it seems to overreact and "snap" making me miss the bottom.  I attribute this to having the logarithmic set to transition too soon probably from adding the canard.  I can't change the logarithmic to fix it on III without replacing it, which I may do, but I can correct in on IV.  The question becomes, do I need a logarithmic at all with a canard?  III will turn as tight a corner as I want to fly and keep the wing in one piece.  I have yet to stall it in a turn or attempt a "bang" corner.  I have done maneuvers with corners so tight as to be annoying to those watching - without any stall.  Never thought that was possible.

I have another question but I will make it in a separate post, so my ramblings don't clog up Sparky's drive.

Ken

To me I built the Sarpolis canard to prove to prove to myself and others that they will fly and do a pattern.  I have witnesses to that when the LA 40 is set right.   So I constructed my version of a Ringmaster canard without the rear moving surface  The canard has no control of the plane until it gets moving through the air.  I had an LA 25 for power.  Had to extend the gear as far forward as I could get it so the plane would not nose over.  Once it got moving and control of the canard started it flew better than I fly.  I learned that is why the Sarpolis canard had the rear moving surface.  It was to keep the nose up until some speed was obtained.   Yes it was strange to look at while flying.   When I get to rebuilding the Ringmaster canard it will get a moving tail surface.  Works like an elevator.

By the way searched for canards on the internet.  A lot of good reading and why people who have built the Bert Rutan canards had to learn a few things.   They don't handle like a Cessna or Piper Cub.    

That was what sketching things in a hurry will do.  I was trying to illustrate the direction with a logarithmic and left that tiny bit of information out.  I will revise the illustration!  Thanks for pointing that out.  What about the other two?

Ken

Got the aft fuselage framed.  The 1 1/6 sides are fine.  The twist capability is next to nil and I don't even have the bottom framing.  That goes on after the pushrod is in.  53 grams including the CF doublers in the unframed nose.  It is going to be a twin so all that will go in the nose is the battery and timer and perhaps the ESC's.  I haven't decided if I am putting them in nose or the wing.

Ken

For what it is worth.  That .3mm CF Sheet is fantastic.  It cuts with scissors and is stronger and lighter than plywoood.  The wing LE is reinforced for the pull test.  I am going to use .5mm for doublers in the motor nacelles.

Nice project!! An ESC does not like twisted motor wires. I would use the motor wires as supplied.

Regards,

Wolfgang

I think that I read somewhere that there is a technical reason to always use short battery wires and long motor wires?  Rather than vice versa.

Steve

My Phoenix Edge ESC´s work with 50 cm battery leads, Maybe cheaper ESC´s need shorter battery leads, because of their smaller input capacitor.
On the top horizontal of the square eights I noticed sudden RPM increase. Do you use the Circuit Flyer timer? That uses a gyro to influence the RPM when turning, I suppose.
Maybe you should test  my new timer, which does not use the gyro, but only keeps the line pull constant....

Best regards,

Wolfgang

What better use can there be for a cheap Chinese spinner than a radar dome doubling as a nose weight box!  Nose is shaping up nicely.  I am having to learn a new skill set to build with everything molded.  Al would be proud!

Tomorrow I build the Canard drive.  All that stuff needs to be in place before I can finish up the nose.  I am itching to start on the cockpit interior.  On the original I used wheel collars glued to the Canard to allow it to slide off of a 5mm carbon fiber rod and therefore be adjustable.  It worked great for about 2 adjustments then the CF rod started slipping.  So that was replaced with an arrow shaft that was fixed.  Both were anchored to the wing with ball bearings Epoxied to the fuselage.  My dream of having an extra surface to trim wings level went "poof".

Ken

I am about to order the ESC's and motors from Russel at Okie.  I will be using 2 BadAss 2320-820's and I hope the Jeti Spin 33 ESC.  Problem is that the Spin 33 is only rated for a 5s battery but it is rated for 26 volts which is over 6s.  I have plenty of 5s 2800 batteries so that would be a good thing but I question if the 5s has enough head room for 2 motors.  I am having fun composing this plane.  I like to do things in random order.  Lots of subassemblies.  Right now I am building out the nose.  I will make the entire front top removable so that I can work on it and glue it on after the wing is installed.  Next step will be the bottom hatch.  That will be the tough one.  Need a mount for the nose gear.  First trike I have built since the 60's.

Ken

The most difficult thing in making a new plane is making the second elevator, flap, or in my case canard.  They do look better with two.  The motors, esc and timer came today.  Haven't laid it all out yet.  I am still trying to place the ESC's where they will cool properly and not be a pain to service.  One question I have not answered to my satisfaction is whether they need to be separated and if so how far.  I will be using a 5s 2800 battery so I can get away with 18 gauge wire which matters since there will be 9' of it from the ESC to the motors!  (3@motor x 18").  "Bing" tells me that the wire will weigh 10 ounces - OUCH!.   I am still shooting for a "start the timer" weight under 70 oz.  I made a decision to go with a Geo-XL wing vs the Geo-Bolt I used on II & III because folks who have been at the electric game longer than I have convinced me that I didn't need the thickness of the GBolt. I sure hope they are right!

Some Pix of the "fun" stuff I have been working on.  I have found that if I build the wing first it wants to fly and I do a hurry up on the fuselage and stab.  So, I save the wing for last. 

The adjustable logarithmic is in the works.  I will skip the cam rudder.  With the separate settings in the Fiorotti timer for each motor I will not have any use for it.  The one fear I have with a twin is an inboard only motor failure.  Have any of you adventurous types ever tried flying on just the outboard?

 One of the things I had to do with III was restrict the bellcrank to 60 degrees to keep it out of the way of the canard pushrod.  I am going to put in a 5" bellcrank to give me back some of the leadout movement I lost plus the extra leverage doesn't hurt.  The 5" will also require some very smooth leadout guides.

Ken
 

Started work on the nacelles.  Got the props in pair of BadAxx 10 x 5's opposite rotation.  That little motor sure is cute.  I don't see how only two of these little things can power a 65oz plane but those who know far more than I do say the will.

Ken

Looks like the bots have lightened up.  Only 70000+ reads.  Here is the proposed power train.  I have never wired a twin so if anything anybody sees that looks strange please post your concerns.  Only one I have is placement of the ESC's.  Some electronic components do not like to be next to each other.  I have no clue if this is true for an ESC.  Probably not.  The rest is just making up the wiring so that you can get it out later if necessary.  I do have a question on the ON/Off switch.  Can one switch serve both ESC's or should I have 2.  I assume one is OK.

One thing that saddens me.  I have always used the 2nd ESC port on the Fiorotti timer as a programming port that I route to a receptacle on the side of the plane.  I don't have to unhook anything, just plug in the Jeti-box to change settings on the timer.   Now I have to plan on an easy to remove hatch for programming. Boo!

Soon as I have the whole thing wired I am going to bench run to see what it does.  Being able to run the motors without a prop - priceless.

Oh, Plan "B" is to put the ESC's on edge to separate them more if necessary.  I want to keep them side by side in the center to keep the wires to each motor the same length.

Ken

Composing an airplane can cause you to say things that are not acceptable in polite society.

Today was wiring day and I was able to get everything crammed into the nose, but the only way to fit the timer and still have access was to turn it with the pins pointing straight down.  You can't bury the thing because you have to be able to unhook the timer to program the ESC's.  With the six motor wires going into the wing the ESC has to be turned around and the leads to the battery box and the "Y" splitters have to go in the front where there is no room then there is that darn arming plug.  Has to go in front of the positive splitter which meant another 6" of 14g wire.  So instead of having it tucked neatly near the wing joint it will stick out like a woodpecker under the canopy.  Either that or 14" of wire.  Maybe I will shape the plug to look like an air-air refueling port.   I had to use more bullets than a John Wick movie just so that I could take it apart later.  With the wiring all in place it was time to check the top and bottom "blocks" to see what it looked like enclosed.  Timer on the bottom, arming plug on the top didn't clear, not even close.  So we now have a fake cannon blister to cover the timer leads and the pilot's left console is now 1/4" up.  It was either that or amputate his left arm.  Having the Canard's pushrod run smack down the center of the nose creates some serious design issues!  I guess that is the price you pay for designing your own.

Reshaped the nose more like a F-86D.  Not exact but close.  All of the pieces are "finished" now except the wing.  34.89 oz with everything, motors, battery, esc's, timer.  All that is left is the rudder, wing and wheels.  I guess I can pull that off with about 15oz which puts me at 50oz.  Finish will be a first for me.  SLC over polyspan with a military paint scheme of some sort.  I am optimistic that I can keep it under 60 which will be 10oz lighter that the single motor Endgame III.

If you are a "tinkerer" like I am you always come up with a better way just about the time you finish a component and that is why we never stop building and rebuilding even when we don't need any more planes!

Ken

Everything excellent! Only the leading edge of the canard looks a little too sharp to me.

Regards,
Wolfgang

Subsonic and in clean air I would use a NACA 0009  :-)

Regards,
Wolfgang

Thought it would be worth posting what this beast will look like.  I drew this up do that I could plan panel lines.  I settled on SLC over polyspan for the finish base after a successful test on the canards.  Everything else on this plane is a first for me, why not the finish!

Ken

Made the wing spars today and cut the right wing ribs. Those Warren Truss ribs sure are long!  It's my first.  Had to make a stripper to cut the spars.  2@ 1/8" x 1/4" strips making a sandwich with a .3mm CF strip of carbon fiber plate in the center (no mayonnaise).  What is so cool about the carbon fiber plate is that you can cut it accurately with scissors. I figured with the motors on the wing and tricycle landing gear, having a beefed-up spar was not going to hurt. 

I will ask it here just for grins since only bots seem to be reading this.  How does one mount wing gear in a Warren Truss wing?

Ken

Control box mounted and pushrods made up.  So far so good.  Elevator gives me 40 degrees in both directions with equal movement of the logarithmic horn.  Next up will be the inboard wing.

Ken

  Normally it would be a 1/32" molded insert but I found that smoothie straws are the perfect size and lighter that the balsa. 

Ken

...and much more colorful!  Nicely done.

Don

 Finally got he wing framed.  Bellcrank and landing gear Monday.  Thought it was time to put it together for a test fit.  Pretty close, needs some work on the nacelles.  Right about now I am cursing Bob for getting me into this but seeing it together has rejuvenated me!

Wing is getting fitted out.  Center spar reinforcement assembled.  Consists of two laminations of .03 CF Plate over a 1/8" balsa core.  This is my new plywood.  Considerably stronger Bellcrenk pivot wire (1/8") goes through the center.  Plumbing for the motor power cables added and cut the openings for the canard pushrod.  Landing gear mounts next.  Todays progress was interrupted by the wall mounted hook to hang Endgame III broke and THUD she fell three feet.  Saved by the collett.  It slipped and let the spinner absorb the shock.  Aside from a broken battery limit - no damage!

Don’t forget, the canard will require moving the CG forward of a normal configuration.

Make a simple sheet scaled down model and tie some string to the wingtip. Swing it around to get some speed over the surfaces.

Move the CG aft till it flops around and you have discovered the limits. I would guess that 10% chord aft of that would be a good starting place.

Actually, my guess is that airfoil has little to do with stability on a symmetrical airfoil wing. Tail and canard area/moments are the controlling factors. 🤠

Back to the build.  Assembled the main components and resized the pushrods.  Found that the Flap gizmo was not giving me enough elevator so I shortened the distance between the levers and now I get 40 degrees with 1 1/2" leadout movement.  40 degrees on a canard is huge so I should be OK even though I had intended my stops to be at 1 1/4" movement each direction.  Controls are so loose and slop free with the new ball links Bob Hunt suggested.
I did have to re-do the pushrods to have more thread exposed.  These links have about a 1/8" recess before the threads make contact - better but if you have trimmed for the DuBro's you are too short!

Added 5/16" cap strips and wingtips glued on (they fit, imagine that).  As soon as I get the gear mounts done the wing gets mounted and I can finally start beefing up the aft wing/fuselage joint and covering up all the false starts that come from composing an airplane vs building from plans 

Ken

Made a new set of flap horns when I found that the dogleg ones from Russel interfered with the logarithmic.  The good part is that the logarithmic tray mounts to the back of the wing so that every part of the control system is accessible for fine tuning.  Most of today was spend making the new horns after wasting half of the day trying to make the old ones work.  Most of tomorrow will be spent recovering from the brain fart of the century.  When I decoded to make Endgame IV I took my "plans" from Endgame III and traced them.   One of the changes I made was to put the horn for the canard on the outboard inner side of the fuselage pointing down so that it would be accessible through the nose hatch and I could use a standard horn.  For this I had to attach the pushrod to the opposite side of the bellcrank from the flap pushrod.  After some discussions with Bob Hunt about twins I decided to jump the shark and go full inline.   So I lowered the canard to the centerline but now the horn was too long to be on the bottom.  The canard doesn't move much.  I have about 3/4" up and down at the TE of the canard.  That equates to about 10 degrees.  I get that with the bellcrank hole at 7/16" and the "horn" for the canard at 1 1/8".  It is adjustable to give me as much as 20 degrees deflection if I want but I doubt I will. 

 No biggie, plenty of room on the top.  That was three months ago.  Today, after making the new flap horns, I hook it all up and marvel at how free and smooth all it is. (Thanks Bob, those ball links are fantastic).  Then it hit me, when the flaps went down, the Canard went up.  Sh.......t. The Canard pushrod was on the wrong side.  The main spar cutouts are cleared for the pushrod to be on the outside of the pivot.  Now they are on the inside. One more hole in the main spar.  Thankfully I used CF webbing out to the nacelles.  Ok, the good news is that the canard pushrod is now straight down the nose center.  The bad news is that the tunnel for it is still angled for the outboard position. and the Cockpit interior is built to hide that tunnel.

The beauty of the hobby to me is that I get just as much enjoyment from building as I do flying and I love to tinker with things. 

Ken

Mounted the flap control box and bellcrank.  Works great.  Absolutely no binding anywhere.  Now I have a question.  I hesitate to ask it here because I don't think anybody reads the build threads if they are in the building forum but here goes anyway.  I have to have trike gear for the twin and I need to place the rear wheels at about 1" behind the CG.  I have no clue where the CG should go on a GEO-XL airfoil.  I know a million other factors play into the exact position but if I can at least get a ballpark I can bend some wire.

Ken

The general rule of thumb for trike gear is that the mains axle be placed at an angle 15 degrees behind the CG.

BTW, those is some nice looking control system parts....