PointMagu

My Feedback: (11)

I've begun the process of cutting a fuselage kit for my Big Kaos. This beast has an 80+ inch wingspan for 1.08 to 1.20 sized 2-strokes. I'll be bolting a Thunder Tigre 1.08 on the nose once completed.

The foam cores are incredibly thick so I'm going to install retracts. I don't want the headache of a nose gear/steering linkage issue so a butt-dragger she'll be.

I have several questions I'd like to throw out there in case anyone has built this plane previously...

The firewall calls for 1/2" ply. Can't find it and don;t like laminating so I'm using 7-ply 3/8" birch from Balsa USA. Does this sound like a reasonable alternative?

The plans naturally show the tricycle undercarriage. Since I'll be moving the gear forward, how should I recalibrate for the CG? AND...
traditionally, how much further forward is recommended for mains when losing the nose gear?

This baby has an incredibly long moment arm and the fuse sides show a 45degree splice with 1/8" doublers. I worry about twist in the tail having those control surfaces so far away from the wing saddle. Has anyone else experienced a problem here?

Since the distance is so great, I'd like to mount the servos in the tail but can't quite grasp how to run dual elevator rods without using 2 servos and a "Y" connector. Any thoughts? As this is a pattern-type ship, I hesitate to use pull-pulls on the rudder but the area is large and my 3004 futaba servo might not like the resistance.

This is my 1st venture into displacements over a .90 and construction techniques are going to be different, I know.

Any feedback/input/advise will be greatly appreciated!


PointMagu

Rcpilot

My Feedback: (78)

Totally fine. 3/8" hard ply will hold a lot of engine.

You don't need to "recalibrate" the CG. The CG is wherever it shows on the plans. You just need to locate your equipment so that it balances on the CG.

For any taildragger, you want the center of the main axles right in line with the leading edge of the wing.

If you can build straight--then don't worry about it. If you can't build straight, then stop right here before you waste anymore money or time.

When using dual elevator servos--it's best to mix then with your radio or another servo matching device such as a Futaba Servo Synchroniser or a JR Matchbox. Smart-Fly sells an Equalizer that works just as well.

DON'T USE A REVERSING Y-HARNESS!!!!!!! The US 1000 is a precision aerobatic airplane and a reversing Y won't do what you need it to do in this situation. Just trust me on this. Do a search for reversing Y harness'. I've covered this more times than I care too. I'm not going to type it all out again. Just don't use one. Do it right and get a servo synchr. or a matchbox.

If your worried about your 3004 Futaba servos on the rudder--then the best thing to do is to buy a more powerful servo. Problem solved.

PointMagu

My Feedback: (11)

'ppreciate the response.

I Have seen dual CG points on kits over the years that offer alternative gear arrangements. This was the prompt for my "recalibration" question. However, I concur with your observation.

Have not heard of the device you mention...never had cause to worry about dual elevators in the past. I can imagine the reasoning against using the Y harness. Glad I asked that one!

My twist concern was prompted more to the fuselage length than to my building ability. I feel reasonably confident that I can utilize the jig and produce a straight construct. But again, I get your drift.

I just purchased a Futaba 7C CAP. I haven't yet assimilated the in's and out's of programming a computer transmitter so I'm hoping that the mixing function you mention is a "doable" for this rig. This stuff has come a long way since my 1st Orbit gear!

Buying a heavy duty servo is the logical choice of course. I was simply looking for alternatives via construction tips. Someone mentioned a tray of sorts, ganging multiple servos in line. Sounded complex...

Thanks again!

PM

jeffo

My Feedback: (68)

Point-
Everything RC says is correct.The dual point C.G. you are refering to is the range you can balance your plane,More foward,more stable,rearward,more aerobatic.Keep in mind if your plane is more nose heavy,you can adjust after flying it.A tail heavy plane flys once.
Why don't you buy a kit from Bluejay Airplane kits?Everything you want in your Chaos is in the plane.I'm covering mine right now.The quality of the kit is excellent.It has servos in the tail,2,one rud. elev.-I am using a 5/32 wire joiner and a hitec 645 servo.It is a taildragger.I am putting a 150 f.s. Saito four power.
I scratch build too,but for 110.00 bucks I don't want to be bothered.
-these are Bridi kits,they bought the rights from Joe.
-Jeffo

PointMagu

My Feedback: (11)

Well, isn't that interesting!

Didn't know Blue Jay existed till I read your post! Unfortunately, I've already invested $85. in wood and covering. To buy the kit at this point isn't financially viable. However, my NEXT Bridi design will be found there!

I noticed from the photo on their website that flying wires are used on the eppanage. If this be the case, then pull-pull for the rudder just got practical.

Thanks for the input. I must have had a senior moment on the CG thing. I could swear what I saw years ago referred to differeing gear arrangement. Oh well...once a CG, always, eh?

PM

PointMagu

My Feedback: (11)

I finally got my Robarts retracts.

Now...how long a gear leg should I make these? With 3-1/2" tires, I figure a gear leg of 5" or so...what are your thoughts?

Photos to follow...

PM

blw

My Feedback: (3)

The Futaba 3004 is probably only sufficient for .40 sized planes. It only has 44 oz of torque. I was going to put 3151s in a .60 sized pattern plane that I'm building but some knowledgeable builders convinced me to chuck that idea for more power. Those had 43 oz and are digital. Your .90 sized Kaos will need even more. Big servos aren't really a waste of money if you consider the disasters from stripped gears, or the misery of controls suffering from blowback and your tracking visably suffering.

PointMagu

My Feedback: (11)

Well, I got the horizontal stab done tonight and the fuselage 90% sanded.

I made the mistake of rounding the nose cone BEFORE I had the engine/spinner installed. The plans call for a 3-1/2" but after my efforts with a sanding block, a 3-1/4" will more likely be the final choice for spinner size. lol.

I have all the wood assembled and 2-8oz bottles of Ultimate Glue ready to do the wing cores this weekend.

This is a big bird! As you can see, it spans my entire work surface.

I'm still up in the air about the length of the retract legs. My US 60 sits 6" off the ground and the 13x6 prop clears nicely. Since I'm running a 1.08 on the KAOS, I'm thinking 7" of ground clearance to be about right. I DO need some helpful input here. Retracts and I are a relatively new relationship :-0. That 7" DOES include the 3-1/2" Robart scale wheels.

I'll try better photos this weekend. For now, these will suffice:

PM

PointMagu

My Feedback: (11)

Well...

Elmer's Ultimate Glue is certainly interesting to work with. It's consistancy is best compared to honey! After trying to spread with convertional brushing, I finally opted on a palette knife and the task was improved 100%...

I opted on spreading coats onto the wood, misting the foam cores and then taping the edges prior to placing back into their nest. I had to do this due to the fact that the cores have been in storage a few years and the foam has compressed to the point that the cradles do not provide tight seals around the outside parimeters.

I may experience slight gapping of the skins but this can be remedied when the balsa LE and TE's are epoxied on.

Ordered the air control kit this weekend and will be getting a large storage cylinder to mount in the aft fuselage compartment. 605HD's get installed next...once the skins are completely set.

Here's a few from today:

PM

MarkD

PointMagu,

What set of plans are you working from?

Thanks,


MarkD

PointMagu

My Feedback: (11)

Mark,

The plans I'm building from were given to me as were the wing cores. They are at least 5 years old if not older.

Here's the photo of them...

Thanks for your interest!

PM

MarkD

I thought it looked familiar! I used the same set of plans (the small ones in the magazine) to gin up a set of cad plans.

It has been flying for 2 seasons now.

I built mine as a tail dragger.

Saito 180 Four stroke

Hobbico CS-70 rudder servo
Hitec HS-77's ( 2) on elevators
Futaba s-148's on ailerons and throttle

You will need at least an 75 oz/in servo for the rudder.

The S-148's on the ailerons have been adequate ( even in flaperon mode), but I will be upgrading this season to digitals.

I still need to play with the balance on mine. It flies very smooth and true, but is sluggish when snapping and doesn't seem to want to slow down for landing. I think the balance is still a bit too far forward. I will be bringing it a bit further back this season.

If you are into CAD I can send you a copy of the file.

MarkD

PointMagu

My Feedback: (11)

Love that scarlet red covering!

I was going to side mount my 1.08 but it's a new engine and I wanted to have easy access in case of break-in issues so upright it is.

How high off the surface does your plane sit? I'm having issues trying to determine how long to make the gear legs on my Robart retracts.

I want to have adequate groud clearance but not make the gear legs so long as to become spindly under the 12+ lbs I know this beast is going to end up at.

What did your project come in at once completed? AND...can you give me a little insight on what method worked for you on control surface hookup?

My largest plane so far is my US 60 running an APS .90. The Kaos will be my "big" plane. All that sheeting on the foam wing begs for 3/4oz cloth and fibreglassing but I don't want the add'l weight. OraCover or UltraKote will probably be my finishing choice.

Thanks for the feedback!

PM

MarkD

If you can open the drawings I think everything you need should be on there.

If you haven't tried CAD before, go to www.deltacad.com and download the free demo. It will only take a couple of minutes to figure out how to open the drawing and zoom in on the details.


PM me your regular email and I can send you some pictures of any details you need.

You will definetly need 7/32" gear legs- i tried 3/16 at first and it was too light. I moved my gear outboard by about 3" per pannel. With the heavier wire and the very wide gear spacing the plane is very stable on the ground, even on a very rough field.

I'm running a 17x8" APC and have about 2 1/2" clearance. I will get you a more precise number.

Mark D

MarkD

With the trustline of the plane paralell to the ground there is 10.5" from the bottom of the wheel to the centerline of the spinner.

I have never had a 1.08 2 stroke- I'm going to guess you would use something like a 14 or 15" prop. That would let you drop the gear height about 1" or 1.5". If so a 3/16" gear leg might be enough. The 3/16 did work on mine even with the longer reach, but it was a bit skimpy.

PointMagu

My Feedback: (11)

I appreciate the info.

I downloaded the Delta Cad. I really would like to get the plans. My email addy is:

[email protected]

The CAD program looks quite intriguing. You may have introduced me to something I may want to explore further :-)

I have a source for a pair of HAWE pneumatics with 1/2" oleos. They came off a big P-51 from some Euro company. The gear are large and weigh pounds. Way too big for my Kaos but the price is right and I MAY come across an airframe to bolt them up to someday.
As thick as this wing is, they'd certainly fit but the weight would push the wing loading too high.

If you have more photos, yes please...send me what you have. I really like the design of the aircraft and am now thinking about the finish and color scheme. I assume your plane has fixed gear? You haven't mentioned retracts. Just curious.

Thanks again!
PM

PointMagu

My Feedback: (11)

After seeing the CAD version, I'm thinking that mine COULD have been so much lighter had I built from your planset rather than my own.

Here's where I am to date. The wing panels aren't joined...this is just for "looks"...


PM

PointMagu

My Feedback: (11)

Leading and trailing edges are now installed and I've begun the process of routing access tubes for the aileron wiring.

I plan on melting out my retract cavities with copper wire inserted into my Weller soldering gun bent to the appropriate templates.

I'm still dinking around trying to find the right location for the retracts. Once I have the final positioning and the recesses carved out, the wing halves get epoxied together and the center section will be glassed.

I have collected all the components for the gear except 3/16" axels for the downlegs. I'm using a HAWE storage vessel with Robart valves and fittings.

I've decided upon a single elevator servo, (Futaba S3302) along with the Cental Hobbies DEPS system. I like CF and their revised compnents now make this system a proven performer. No dual elevator servos in the tail group. Rudder chores will fall upon another single 1/4 scale servo utilizing pull-pull and a bellcrank, ala MarkD. Thanks, Mark!

I'll be posting a few photos this weekend illustrating my next obstacle: running the pushrods aft around the oversized HAWE storage cylinder. I may have to mount the thing atop the wing center...

Thanks for looking!

PM

buz2au

G'day MarkD,

Just wondering if I could get a copy of the cad plans also

Cheers

buz2au

kdheath

If you lay out the plan side view, lay out the largest prop you think you'll use, or just draw something to indicate the length. Add, what? 2 inches clearance or a little less. Your ground line is then drawn through that point, parallel to the thrust line of the plane. Set a main wheel in position, prop a retract assembly in place, and measure the gear length. Isn't exactly science, but it''ll get you close enough to get an idea how it will work out. Make the leg as short as you can, to reduce the load on the retract unit. The longer the leg, the more oomph it takes to lift the wheel. Just assure that the plane can run on the mains, on the ground, in a level attitude, without digging in the prop. BTW, thefancy formula for locating mains on a tail dragger is to locate the axles at a 17 degree angle forward of the center of mass. Curiously,this is pretty close to the LE of the wing most of the time.

MarkD

If I were to do it again, I think I would leave out the bell crank and just run the pull-pull cables to the servo.

In a really LARGE plane with multiple rudder servos the bellcrank method has its advantages.

For a single servo setup, it's overkill. It does take the tension of the cables off the servo bearings, but then you don't really need very much tension to begin with.

Mark D

PointMagu

My Feedback: (11)

Ok, well here's how I ended up on the retract issue...

I took the plans and drew the prop arc as advised. I figured on a 16" prop so 8" from the thrust line was my measure. I factored the gear legs at 6" from pivot and with the Robart 3-1/2" wheels, ground clearance should be optimal.

I worked the geometry back and forth until I finally gave up and "eyeballed" the dang things and commenced cutting my wheel wells.

The wing is thick enough to allow for the slight angle the axels will have and the angle that the wheels will take when fully retracted into the wells. I think things will be fine....(I hope).

Here's a few snaps:

PointMagu

My Feedback: (11)

Wow...

Been awhile since I posted but I've slowly been working and assembling parts and stuff.

Here's a few of progress to date. I had to CA strips of CF to the trailing edges due to overactive sanding, lol...

PointMagu

My Feedback: (11)

Here's the latest update on the big Kaos project:

Tail group finished off and ready to install. I'm waiting on 2 hi-torque servos I picked up off eBay. They were incredibly cheap, ($12. ea), are coming from Hong Kong and have been kicked around on this site in other forums.

Once I get them, I'll cut the access holes on the aft fuselage, measure the pull-pull wires for the rudder and then affix the horizontal stab and fin-rudder.

I'm looking for a bellcrank for the rudder wires or else I may simply make one.

Here's a few pictures:

PointMagu

My Feedback: (11)

Finally got the canopy and most of the hookup accessories. Here's a few from this evening...