PacificNWSkyPilot

My Feedback: (19)

I've spent a little time talking back and forth with one of our guys here who has no low-tail issues. He balanced his the old fashion way, he started on the spar/joiner bar and took it from there.

For those who don't know me, I use Bill Hurt's descriptive terminology "Center of Balance" in place of CG.

According to him, his Center of Balance is right at 3-3/4 inches back from the leading edge. Factory recommendations are 4-1/4 to 4-1/2 inches. So, at the very LEAST we are a full 1/2-inch forward of the factory recommendations, and AS MUCH as 3/4-inch forward of their recommendations. That's a LOT of difference, certainly enough to cause the tail-dragging some are seeing.

A small but very important difference.

So, I'll use this 3-3/4" CB when I put mine together, and we'll see how it flies!

I also just received word from Todd Syssa, he should be getting my 30CC Syssa gas engine out to me this week. So we'll be able to keep the build pretty much on track if all goes well.

Yeah!

Jimbo

PacificNWSkyPilot

My Feedback: (19)

quote:

ORIGINAL: TexasSkyPilot

I just couldn't resist working on those wheels, I was pretty sure they'd fit into the wheel-pants, and I was right! Plenty of room to spare, in fact. Must be AT LEAST 2 mm's on either side of it! Okay, maybe at MOST.

Yeah, it was a little tight, but the end product was worth the work. When you look at the photos below, tell me what you think. I don't think the wheel is sticking out too much, and I think it's going to be GREAT for flying off the grass fields that I love to fly at.

The way these wheel-pants are set up, you can mount the wheel on the axle, then slide the pant up onto the gear/axle over the wheel. It's pretty nice. I've been a wheel-pant enthusiast for many, many years, and keeping the wheel-pants on a plane is one of the toughest things around. I have a secret for this. No big deal, but it works great. One of the hardest things on a wheel-pant is flexing. If you were a little piece of flexy fiberglass and every time you take off or land you got shaken up and down pretty hard, you'd fall apart too. So, very simply I brace up the outside of the wheel-pant. Now, we don't want our axle coming through and showing, that's just tacky. What I do is I drill a small piece of something like lit-ply or spruce so that it fits firmly over the end of the axle, then I slide the wheel-pant up and over it and fasten the wheel-pant to the Gear using whatever method. At this point the little piece of wood is inside the pant and up against the side of it, the side which we have already been smart enough to rough-up with sandpaper. Simply drip a few drops of thin CA onto the area where they meet, and walk away for a few minutes. When you come back, the wood will be fastened to the wheel-pant, and you can flex out a little and remove the pant and put a fillet of CA glue around the bit of wood for strength. Viola! My wheel-pant is solid and supported! If you look closely at photo 2 you can see the little bit of support wood I've been talking about, on the left between the tire and the pant.

One more thing. When you finish lining up the wheel-pant and you are ready to mount both tire and pant permanently, remember on your final assembly to use a drop of blue locktite on each small screw in each wheel collett, and each small screw going into the T-bolts in the pant. Before you do final assembly....Do your wheels roll smoothly? I found that the wheels that came with the kit fit tightly on the axle...TOO tightly. I found a drill bit that was just a wee-bit larger than the hole already in it and gave it one more pass. The wheel would turn smoothly after that. I used the same bit to ream out my Sullivan Skylight wheels, and they also turn very nicely on the axle. Tight wheels can cause BIG issues with ground handling.

* * * * * *

KenCZ:

TSP-
So just to clairify the wheel pants support block: As I understand it the small piece of wood with a hole in it ends up sitting on the axle on the inboard side and bonded to the inside face of the wheel pant on the outboard side? Correct?
How much engagement to the axle do you allow? 1/8 inch or so? This would be controlled by the thickness of the wood block if I my understanding is correct.

Thanks,
Ken

PacificNWSkyPilot

My Feedback: (19)

Hi Ken,

Yes, in fact you can add to the thickness if you need to, depending upon the distance you need to cover. You described it accurately.

It can rattle a little if you like, I just like it to be firm so it doesn't move much. Less stress on the fiberglass that way, but a little more work (Like an extra 10 seconds) to get on the axle when you slide the pant over the wheel.

There's no maximum depth on the hole for the axle. That's usually limited anyway to about 1/4" to 3/8" at the very most just by the small amount of space that's available going over the wheel.

I really never have wheel-pants fail. Except when that Bipe crashed ten years ago. (Crashes don't count!)

Jimbo

PacificNWSkyPilot

My Feedback: (19)

Well I got home pretty late tonight, so not much building will get done. But I did find the time to select my servos, so I'll go over that with you.

The manual says that they use a high-torque 70 oz-in servo for the rudder, and standard 46 oz-in Ball-bearing servos on all the other surfaces.

It's nice to know that standard JR 517 servos would work on this, but I'm afraid I'd be stopped at the first giant-scale safety inspection, the last I knew they required giants to have a minimum of 60 oz-in servos on all control surfaces. So I decided to make sure it will pass at the event field inspection, and I also wanted to make sure I was satisfied, but I was also thinking of the average Joe who wants to put one of these together without spending a fortune. I was very happy with the servos I decided upon, they didn't cost a fortune, and they'll do the job VERY nicely as well. Now, these servos came out of my servo stock, all new but still in their packages. The prices I'll be giving here are probably a year and a half old, you may have to adjust some for today's prices and maybe they have upgraded models of the servos now as well.

For the elevators I went with two of the JR ST126MG servos. The sticker for the hobby shop showed about $34.00 each. I run 6-Volt battery packs, so the rated torque on these servos is 142 oz-in, WAY more than what is required, but not a pricey servo and so I said yes to them for my elevators, arguably the most important surfaces on the plane. I feel pretty good about them.

For my Rudder I came fairly close to their recommended servo output by using JR DS821 servos. They show 72 oz-in at 4.8 Volts and 88 oz-in at 6 Volts. Shouldn't be any problem with that one.

I also went with the JR DS821's for each of the ailerons. Well above the recommended threshold and good for giant-scale meets. The DS821's had stickers showing about $28.00 each.

For my throttle I simply grabbed a used JR 507 out of my "used" box. Should work fine. I'm also thinking of using a servo for actuating the choke assembly, but I'll wait on that decision until I find out what might be needed for nose-weight. I have a handful of used servos that for some reason are missing an ear and can only mount up with 3 screws. I often use those for throttles. No idea how they got that way, because I NEVER crash.....almost.....LOL

So, that's what the 'Coupe will be servo'd up with. I'll see you tomorrow! Hopefully I'll get home in time to do some more work and get some more photos out here.

I went over the aileron hinge installation, and these guys did a great job of setting up the hinge holes, these aileron hinge joints are spot-on.

Jimbo

PacificNWSkyPilot

My Feedback: (19)

Lotsofcrashes:

"You never Crash ?"

* * * * * *
TexasSkyPilot:


Define: "NEVER"..............!!

LOL

After all these years, almost never. Things happen beyond our control at times, though, so every now and then..........


Jimbo

* * * * * *

Lotsofcrashes:

"I'm smiling, I crash a lot but I am learning."

* * * * * *

TexasSkyPilot:

We all did. Sounds like you've got the right attitude and the determination not to quit and to become better at it. We all had that too. Those of us who didn't? Well, they're not here anymore!

Carry on bravely! You're doing great! That's why they invented glue!

Jimbo

PacificNWSkyPilot

My Feedback: (19)

Ed Posted:

" The funny thing is that I'm the one who notices that a certain number of these aren't flying quite right. Now I've got guys stepping up and pressing their expertise and telling me that these tails are supposed to settle in flight. " - Jimbo

The reason that I jumped into this thread, is because Jimbo has noticed the same thing that has been happening to me all along. My Clipped Wing Coupe's ***** is dragging ! And from what I'm hearing .... I'm not the only one that this is happening to. I'm now inclined to beleive that the 4 1/2" balance point called out in the manual is wrong.

Unfortunately, I cannot get back to moving the balance point forward, until I get back to flying that particular airplane. I've got 4 other big birds to rotate thru and fly, before I get back to tinkering with the Coupe. ( Got a couple of Big Bird events coming up here very soon, so I can't do it now ) ................. So stay tuned.

Ed

PacificNWSkyPilot

My Feedback: (19)

Lotsofcrashes posted (paraphrased):

I'm interested in basic things like whether the wheels rip off for some reason every time you land, and weaknesses in the plane that see it in the workshop every time you take it out. To me thats a guide as to whether I will buy a plane I have been reading about in the threads.

I have followed this thread and build for awhile now and I like the look of this one.

PacificNWSkyPilot

My Feedback: (19)

Thanks, Ed. I think we're on the right track with this. And lotsofcrashes, stay tuned, I like the looks of this one too.

Unfortunately my Boss thinks we have to work until midnight every night this week right up until Wednesday night, I guess he's determined to get those 40 hours out of me anyway.

Once he's done torturing me with lots of nasty work I'll get back on the build. In the meantime the Syssa gasser gets closer every day to being here.......

As for the balance point in the manual being wrong (if indeed that turns out to be the case), that's an easy fix for the manufacturer, and it's still do-able because they're still in production. Not like the Pica Waco where Bill and the guys finally re-adjusted the Center of balance. Oh, and....Now they fly right. I was amazed at how many guys used to think that a Waco model was supposed to land every time in a 3-point attitude.

So, let's see where this takes us. If it turns out that it is that simple, we can just work with the manufacturer, or probably more likely Pacific Aero, and a simple text adjustment in the manual makes all the foolish talk about carving it up and changing the angle of attack go away!

It's always been my experience that the simplest solution is often the best.

It's also been my experience that the folks who love melodrama like the complicated, round-robin's-barn way of doing things.

Jimbo

PacificNWSkyPilot

My Feedback: (19)

Okay, posts from here on are in Real-time.....no reproductions.....

Thanks!

Jimbo

splais

My Feedback: (25)

"6 5/8" is the standard clearance. You want an inch, you'll probably want 7 5/8" Why so much? "

I'm still gathering info in preparation for getting this plane and the Syssa 30 engine as my next project. I would have preferred the Aeroworks Cessna 195. But at twice the price and a maybe release date in March/Feb, well you know how that goes. I love the look/covering scheme of the Monocoupe anyway. I currently have an M-12 Pitts and have had a couple of other large round cowl 50cc birds. Found they seem to fly a little better with some clearance, in most cases it is also more scale. That being said, after looking at a couple of pics, the prop on the Monocoupe was smack dab up against the cowl on the real bird. Your numbers are hard to interpret - how much clearance does that 6 5/8" give you? it would seem 7 5/8" would give over an inch, if the 6 5/8 has any clearance at all. /Steve

GaGeeBees

My Feedback: (23)

Subscribed and looking forward to watching your build. Hope your engine arrives soon.

Ed

Better luck here in this thread Jimbo !

And while I got your attention .......... What diameter, and brand name tail wheel, do you plan using on that Sullivan rig ?

PacificNWSkyPilot

My Feedback: (19)

Thanks guys!

And Ed....Well.....I just hadn't thought about that so far! I've had a passing thought or two about it. I guess I'll take a look at what came on the original steering gear and pick out a similar size. I have a pretty good assortment around here. I'll let you know!

Splais,

I agree - it also looks to me like the prop is pretty close in the photo.....so I'll guess that 6 1/2 inches of it are all cowl with an 1/8th-inch clearance. At this point I don't have it measured out, since I'm still waiting for my engine I haven't had the need to measure all that out. The truth is, my engine is coming with a total length of 6.5 inches to prop washer, so I knew I was going to be within a 1/8th-inch shim of being right on the money.

~J

Lifer

My Feedback: (1)

All,

My CWP is about 2 years old. It does fly like a big trainer. For an engine, I used an SPE 43 cc. The cylinder barely protrudes out the bottom. The back end of the muffler protrudes out of the side of the cowl. I pointed the engine straight down. Had to remove the cowl mount that would be at the 4 o'clock position to clear the muffler. Simply fabricated a secondary support for the cowl near the old one. (Sorry; no camera, no pictures)

Balance was on the money with this engine and with the servos in the back. I fly it with the M.A. Simitar 20x8. It cruises effortlessly at 60 mph. Lands without the flaperons using just rudder and elevator. I'm getting the new Airtronics SD 2.4 radio for my birthday and when I install it, I will increase the rudder throw and then add expo to the rudder stick as my current radio doesn't have that feature.

I've been disappointed with the service from PAC but the plane is an absolute pleasure to fly nonetheless. Full speed passes down the runway are real cool and with the powerful rudder many acrobatics are possible. I reccomend this plane!

PacificNWSkyPilot

My Feedback: (19)

Hi Lifer, and welcome to the 'Coupe Build thread!

Thanks for sharing your findings. Sounds like you really enjoy yours.

I'm just curious, why were you disappointed with their service? I found that my phone calls with questions about this or that were not returned for a good day or two, but in this industry that's not at all unusual (but still frustrating). But he DID return the call eventually and apologized for being crazy busy there, and answered my questions. When we called to place the order on the order line he answered and shipped out the goods immediately, we got them really quickly. THAT is unusual in this industry for a smaller company (Horizon, Tower, those are BIG companies).

Like you said, I find that the model itself I am VERY pleased with. And I haven't even gotten it in the air yet!

This 'Coupe is very easy on the eyes! If I never flew it (fat chance) I'd still enjoy having it just to look at.

Jimbo

PacificNWSkyPilot

My Feedback: (19)

Ed!

I have answers!

Okay, I went out and dug around, and as you know I already had gotten this 10 to 22-pound Sullivan Steerable tail wheel gear. I believe what I found to go with it is a Sullivan wheel, it has a flat bottom, has fairly hard rubber, is a little shiny (oh well) and has a solid aluminum hub. Fits the axle perfectly with very little rattle or slop. Like the original wheel it is 1", but I am partial to the flat-treaded wheels for steering. That probably goes along with my affinity for grass fields as well.

Once again, nothing fancy or expensive, but I know this will steer it well and do a good job. And MAN, these gear are TOUGH.

~J

PacificNWSkyPilot

My Feedback: (19)

There are other issues besides tails dragging, such as poor handling. MOST of them don't have this problem, so I was looking into what might. Here is an excerpt from Page 7 of the Instruction manual reminding us that this Classic plane flies in a classic fashion, and requires Aileron Differential. Most of you guys know what that is. For the rest, it's simply this: Ailerons go up and down, but Flaps go down as well. You can probably see where this is going. Flaps create drag and lift, and ailerons are simply meant to change the location of the wing through louvering it, for lack of a better word. (Because moving the surface changes the shape of the wing it actually DOES involve "lift" and all that, but this will serve here.) When one aileron goes up, the other goes down. Quite a long time ago aero-engineers discovered that having less throw on the aileron that's going down than the aileron going up will help the plane to roll more axially, which just means it stays on the same trajectory rather than moving about while it's trying to move the wings around the fuselage. (I hope I explained that okay)... So, that's called Aileron differential. In essence, it prevents the aileron from moving downward too far and acting as a flap.

Here's what the Instruction Manual says:

AILERON DIFFERENTIAL. The Monocoupe will not fly well without aileron differential to offset adverse yaw. The simplest way to set up aileron differential is to use separate channels for the ailerons.(Preferably by using the Flaperon function of your transmitter.) This way you can set the differential travel by simply adjusting the up and down ATV/EPA for each channel on your transmitter. (The recommended control travels are given at the end of this manual.) If your transmitter doesn’t have the ability to mix two aileron channels, you can get the required differential as follows: Center your servos with the transmitter, then install the aileron servo arms two splines toward the leading edge from the normal 90 degree position.

I cannot find a way to move the photo from the Manual here to show you how a manual Aileron differential is set up on a servo, because it is a pdf file. I couldn't get alink to that Page (Page 7) because of that either. So, here is a link to the manual and the photo is on page 7.

http://www.pacaeromodel.com/MonoC/Manu/Mono.pdf

The way I explain a manual servo setup is like this; Think of a round servo arm in the same shape as a clock. With the servo pointing at 12:00 and 6:00, and the aileron running across the bottom past 6:00. When we used to set up both ailerons on the same servo ON THE BOTTOM OF A HIGH WING we attached the linkages on the round servo arm at the 10:30 position on the left side of the servo as it faced us and the 1:30 position on the right side. When the servo actuates, pushing TOWARD the aileron it has full travel all the way down as far as it can go, which usually would be in the 4:30 position or so, or on the left the 7:30 position. This is important. Now, watch the servo as it actuates AWAY from the aileron, it doesn't actually pull AWAY from the surface as much as it STARTS to move that way and then travels across as the linkage is pulled past the 12:00 position. Both sides move that way. Which ever side is moving TOWARDS the aileron is moving that aileron much more than its counterpart on the opposite side is moving away from the aileron. Instant differential! Of course, we can set the arms at 90 degrees and then program that differential right into a computer radio now, but I still enjoy setting up smaller models with this setup just for old-times sake. Note that if you are doing this with a low-wing, the servo is then ON TOP of the wing so you'll want to make the appropriate changes, such as moving your attach points to 4:30 and 7:30.

And of course, with the 'Coupe we are using separate servos, so nothing is changed except that we treat each servo like one side of the description above, the left or the right. Remember, in the end what we are trying to achieve is each aileron going UP more than it goes DOWN. Aileron Differential!

~J

TooLow

My Feedback: (5)

Thanks guys for keeping this thread going on this glorious bird. I have two of them and had to weed through the nit-picky problems myself. Having read that a few people have them flying in the "tail dragger" position tells me that they are not balanced quite right. Dont be afraid to deviate from the instructions and change your CG foreward. Just takes moving a bit of weight and no surgery! Mine balance about 1/4" ahead of the alum joiner spar and are real crisp when doing aerobatics! They fly with the tail flat not dragging their bums around the sky!

PacificNWSkyPilot

My Feedback: (19)

Excellent, TooLow,

Thanks!

TooLow's extensive experience with this model is kind of inspiring! I'd love to hear more anytime!

Jimbo

PacificNWSkyPilot

My Feedback: (19)

I've just been notified that after careful consideration (considering all the beers that went into getting the creative juices flowing and formulating the plan) that a Model-sized Vanessa Rig is going to be placed into one of these birds so we can remotely move the weight during flight until the airplane is flying perfectly. This will enable us to then test the model and ascertain the EXACT position of the actual Center of Balance.

Tell me this is not FUN!

Thank you, secret un-named tester! And of course, Budweiser. Or Heineken. LOL

~ J ~

tkg

My Feedback: (1)

Real old school CG check.
1. Balance plane according to Mfg instructions.
2. Fly plane adjust trims for level flight at WOT.
Now comes the important part
3. Fly level at WOT, pull up to 45 deg upline, roll inverted, remove hands from controls.
IF the plane noses over its nose heavy
IF the plane climbs (outside loop like) then its tail heavy.
Explanation
Nose heavy, you have to trim up, so inverted it becomes down trim and the nose weight makes it worse. The 45 degree upline slows things down a bit.

PacificNWSkyPilot

My Feedback: (19)

Thanks tkg. Very similar to what I do with my friends' planes when they ask me to check them out. A plane that changes dramatically when you invert it from flying flat and level is an immediate indicator of heavy nose or tail, typically, as well as detecting compensatory trim dialed in for the problem. I like your 45-degree upward angle, that's a good twist on it, it kind of neutralizes the plane so that the tendencies can show themselves more clearly.

Excellent!

I just finished installing the aileron servos but not the linkages yet. I'll be installing the rudder servo next here tonight, but I'm going with an experimental servo, not a JR. I have a friend who asked me to test out some of these servos, they have like 200-plus oz-in of torque, they're digital and metal geared. And not very expensive. I had a fellow poster (OldFart1) recommend that I not use the DS821 servo on the rudder. I don't think it would have had any issues at all, I've used them before, but it's no big deal. I have lots of latitude here, I'll use this new one and see how it works out.

~ J ~

Ed

" I had a fellow poster (OldFart1) recommend that I not use the DS821 servo on the rudder. "

I've had tremendous success with the DS-821, JR / Spektrum servos. In fact, I bought a bunch more. And at 20 bucks a piece, I consider them a real bargain.

Ed

PacificNWSkyPilot

My Feedback: (19)

Ed, I too have had great luck with all of the JR or Spektrum servos that I have used.

Are they 20 bucks apiece? I think I got robbed! LOL

If something really matters to me, it gets JR servos.

But a promise is a promise........ and I figure the rudder is a decent place to try one of these other ones out.

~ J ~

AJsToyz

Jimbo,

Found ya !! I'll go back and read more , you are a typing machine !!

Andy