Zeeb

My Feedback: (41)

Okay guys after numerous delays on Hitec's part with getting out the new 7XXX series servos, I have them and most of the stuff to start putting mine together.

Actually though the Hitec delay let me get into a new JR 12X so it wasn't all bad, great radio bye the way....

Any way, what if anything, are you guys using single aileron servos doing with the slot in the outboard servo cover?

tetsa

Hello Comp-Arf Extra 260 Fans!

It's time to wake this thread up from hibernation, and it's also time to put the 260 on a diet...

During the last flight season I flew the 260 quite a bit. I was very happy with the performance but I thought it could be better if I could shave some weight off.

And so it happened that on one particular flight I simply ran out of petrol. ('Cause the plane was at it's best when the tank was almot empty...) I couldn't make it back to the field but I did manage to land the plane wings level at walking speed on rome rough ground. The landing gear basically broke the front part of the fuse. This could have been easily repaired, but it gave me an excuse to order a new fuse, since the repairs would have added quite a bit of weight.

So... The plan now is to strip a bunch of servos out and generally 'think light'.

I got the DA-85 with KS 1090 tuned pipe, I'll change the wing and rudder servos to single 8711's and get rid off the large Powerbox Royal and replace it with simple regulators.

The only problem I can see is that the mounting of the rudder servo needs to come up from the bottom of the fuse because of the tuned pipe. No big deal though...

I'll keep you posted.

Cheers,

Tero

BaldEagel

Tero

Great idea, I will be very interested in how you going to offset the heavy tail with the lighter DA85 up front, this should make interesting reading, looking forward to it.

Just an idea, how about moving the tail servo's into the cockpit area and close loop linking them to the elevator, similar to the rudder? You could also use one quarter scale big powerfull servo for the elevator and rudder respectivly, it may be a weight saving overal not just at the tail end.

Mike

tetsa

Mike,

For me it seems that the sweet spot for balance point is well behind the recommeded aft point. So I'm not TOO worried about moving everything as far forward as possible. I think I'll build a light-weight tray for the batteries in front of the firewall, though.

But I'm sure I'll keep the elevator servos at their current location. I will drop the other rudder servo as well, and replace the combo of 8511's with a single 8711.

In my current set-up (with the DA-100) I have about 200-300 grams of dead weight just in front of the rudder as ballast...

bubbagates

My Feedback: (32)

Wow, that much weight with that engine...something was not quite right. Changing out the Royal to regs is only gonna save about an ounce or two, been there done that. The Royal alone is only 5 ounces, twin regs are gonna be that same weight

I have the same plane and I'll tell you if you are after 3D performance, going to one aileron servo is gonna hurt you big time ion control. Your battery drain is gonna go through the roof not to mention the gears in each are going to need replaced way more often. My rudder is on one receiver, the battery on that receivers uses around 400mah more over 5 flights than the one without the rudder servo and that is doing an IMAC sequence which is a heck of a lot less load than 3D

I'm at 29lbs on mine with this setup. I could save 1 full pound by going to Li-ION and the thing locks on like there is no tomorrow

DA100
MTW75K cans
3 Jet Black 2300 A123 batts One for ignition, 2 for the receivers
2 AR9000 receivers (no real reason other than I had them and wanted to try duals on 2.4
2 8611's per wing using a matchbox per wing
1 8711 on the rudder
SWB arms all around
H9 Titanium links all around
32 ounce Dubro tank
Tru-Turn spinners (2 or 3 blade, depending on what I'm flying)
2 or 3 blade Mejlik props
Smart-Fly ignition cutoff

Now I admit this engine is well broken in and will rip a 28X10 at near full throttle, forget about a 27x10, I'll rip that just running it on the ground

Now if I wanted to, I could lose a pound in batteries, taking into account adding regs, another 8 ounces in changing out the wing/stab tubes for CF, removing my pilot and dash panel but sine I fly IMAC as well I need those items

A DA85 is gonna shake that plane like nothing you have ever seen before.

One thing to remember is you can get too lite in weight. 3D is not all about weight savings, it's finding that balance between them.

I'd stay with the DA100, change your wing servos to 8411's (you'll save 4 ounces right there) Change the rudder to 8711 (there goes another 4+ ounces) Leave the Royal but do not leave the remote screen hooked up in there and since you did not mention what batteries I'd go with Li-ION in the 2600Mah range for everything. I get roughly 7 flights on my receiver batts and I could probably get more but since you cannot really load test a A123 cell, I'm not pushing it. Change out the tubes for CF

Depending on your muffler choices, you could easily see 27.5 to 28lbs which is pretty respectable for that plane

One other thing to think about, using a KS1090 is gonna put you right back or very very close to the same weight as a DA100 on mufflers.

My plane

tetsa

Bill,

Thanks for stopping by! My Extra at the moment is at 28 lb, with a set-up very similar to yours. (with MTW cans and so on...) I just feel that the plane could be better with less weight.

If my experiment doesn't work out it's pretty simple to go back to the old set-up. The only worry for me is the vibration of the DA-85.

bubbagates

My Feedback: (32)

After doing some checking, you will lose some weight going to the 85 and pipe. You may want to check out the Greve pipes if you can get them where you are at. Similiar in price to the KS1090 but about half the weight and a couple more hundred rpm than the KS version.

You could also go with a 24 ounce tank and keep an eye on time. That will reduce your airborne weight. I know I typically have 1/4 tank left after 10 minutes of IMAC flying but I like having the extra fuel for those times the judges hold me in the air or I forget to set the timer

Greve pipes can be found on DA's web site

To help with the vibrations, try using some 1/4 inch square balsa sticks right where the turtle deck starts, below the canopy line that go from one side to the other. That seams to be the weak point of this plane. You could do one straight across, or lay two in there that cross each other that will form an "X". I put one stick down low in there to help keep my rudder cables separated and noticed the vibrations went way down, not that the 100 vibrates all that much

I definitely would not go to single servos on the wings, you will not like the response, just go to the 8411's and you'll lose about 4 ounces across all 4

I think going to CF tubes, the 85, the Greve pipe and 8411's you could get another full pound out of it, if you use the KS, maybe 12 to 14 ounces (not quite a full pound) The hard part is getting it to balance.

I'm like you, I know I'm closer to the back edge of the CG if not a bit past it but it flies just fine there. If I do a 45 degree upline and roll it over and let go, it takes about 10 seconds to come back to level which is right where I like it. Sounds like you may be pretty neutral or just a tad tail heavy

I'm not a 3D person by any means so I like mine right where it is, snaps are dead on, things like that

Also, something you might want to try, especially if you are going for pulling power is instead of going with all of those changes, try a 26x12 2-blade, the 26x12 will spool up way faster than a 27x10 and give you the punch you might be looking for. On my 100 I need a 27x12 and when I use that prop, the darn thing goes uphill in a huge hurry. The occasional hover pulls out well. I tried a 26x12 and it was better but I was ripping that prop as well (ripping equals too many rpms and that's bad)

Just some food for thought

WinginIt

My Feedback: (17)

Bill,
You are the first person I have heard against 1 servo each wing. My friend and I have been flying ours ror almost 2 years now with 1 5955 on each wing. I have right about 100 flights on mine and I am into 3D. Our flights are always very extreme when it comes to high speed manuvers as well as stall speed ones and we have had no problems with response time or servo probs.
Mine flies at 27lbs 5oz without smoke fluid (recently installed). Do a lot of high speed snaps and walls, etc.
The ailerons have no flex in them what so ever and the one servo on the inside is all that is needed.

imho,
Doug

You can see my setup back early in this thread if you haven't looked already.

bubbagates

My Feedback: (32)

Doug,

Maybe it's because I'm more into IMAC and a single servo at the root kills the snaps and this thing does some of the best snaps I've ever seen with twin servos, I had a single 8711 in them originally at the root but did not like the snaps, I found the delay to get auto-rotation going and then get it stopped, right on line, especially 1 3/4 snaps to KE, seemed very slow starting the rotation compared to twin servos and over-rotated at least 1/4 turn. I like fast, in your face snaps on low rates with instant stops

Since we are mainly talking 3D here I'll let you all hash that part out since I'm not much of a 3D person. I'm still concerned though about the 85 and the area around the turtle deck.

Sorry guys....no harm, no fowl

WinginIt

My Feedback: (17)

I can respect that Bill. Especially since you flew with one before two per wing. Imac is a much more precise flying than I do so I will concede that you probably have something there.

tetsa

Guys,

Nice to see the old thread come to life again!

Bill: I actually HAD the 8411's in the wings, so I know what you are talking about. But since my main goal is to get rid off all wing rocking in high alpha I see no other way to go than loose weight. I feel that I've tried everything else.

My balance point at the moment is probably more aft then yours since from 45 degree upline my plane will eventually go vertical. Landing it requires some pushing. Which suits me fine. But still it's nice that from the same basic structure you can get a nice pattern plane or a pretty serious 3D performer!

You're idea of the balsa sticks across the fuse seems very good, I will surely give it a go.

I will also try to smooth out the vibrations by using a secondary firewall and some rubber grommets between the sec. firewall and the stand-offs if I can find suitable ones.

In all honesty I must say that since quite a bit of my flying is done well under 30 feet and I do like to try out new tricks, I would be hugely surprised if the servos wear out from vibration before I crash the thing... [:@]

bubbagates

My Feedback: (32)

I'd say that's bad karma right there...[:@]

Yep, that's tail heavy

Have you tried reflexing the ailerons up. I used to have a mix in mine that once switched on and I had full up elevator, I'd get full up ailerons on both sides. You could make it proportional if you wanted to

Damn plane would literally drop straight down and no wing rock, well maybe a tad if it was windy. I actually had the mix to go both ways, full up elevator equaled full up aileron, full down elevator equals full down aileron. The full down was for inverted stuff and totally killer KE spins.

Besides, there's nothing like a Comp-Arf with full up aileron on both sides screaming as it comes down in a harrier [X(]

tetsa

It's not karma, just statistical mathematics... when I stop wrecking a plane once in a while, that's the day I'll take up bird-spotting. (not that there's anything wrong with that!).

Tail heavy, yes. Still just about how I like it.

I've tried the 'both-aileron-up' mix and I must say that I'm not a huge fan. While it dampens wing rocking, it also makes the plane move in a weird way. Matter of taste I'm sure but not for me.

Anyway, I've now received some laser-cut plywood for the secondary firewall. Drew it up on Autocad and sent the file by e-mail to a local laser cutter. Two days later the pieces were in the mail. So pretty soon it's time to fire up the old Dremel and start cutting some holes in the nose!

WinginIt

My Feedback: (17)

Post some pics of your progress, please

tetsa

Well it's getting a bit late here in Finland (well past midnight) but still I thought I'd share a few pictures.

To be honest I haven't really made any progress 'cause of other stuff getting in the way. But still here's pic of my secondary firewall bolted to the engine. Nothing breath taking there...
In the second pic you can see that I've marked new locations for the bolts that connect the secondary firewall with the 85 to the actual firewall. The reason I had to relocate the bolt holes is that I didn't notice at first that the plywood doubler behind the laminated firewall was quite a bit more narrow the the nose cone. Luckily I checked inside the fuse before drilling... I've drawn some lines in photoshop on the bolt locations to highlight them.

I actually had a spare 3mm layer of the sec. firewall cut so that I could use it as a template for cutting the hole for the carb and to drill the bolt holes. I then taped the nose cone and glued the template on to the taped surface with Titebond.

That's about it. Also I've been taking measurements to design the header bends and pipe location with in the fuselage, but I really have nothing to show for this. The 300mm long header will have to be routed under the engine on to the other side of the fuse and then taken through the motor dome.

Until next time!

Cheers,

Tero

tetsa

A little bit of progress here on the 260. I drilled the firewall for the secondary firewall and made a hole for the carborettor.

I also silver-soldered the header pipe from KS 28x0,5mm pipe, elbows and flex pipe. Everything seems to fit nicely. The spark plug cap may hit the side of the cowl, so a small hole may need to be made for it. Obviously the header - pipe installation is only at mock-up stage. I'll use the KS Comfort Mount to install the pipe.

I've been building a glider tug (Top Model 'Bidule 116' ARF with MVVS/Evolution 116, a fantastic combination!) for next season, and now that I have finished it I can put my focus on the Extra. Hopefully I can make some real progress now!

cesar781

Hei tetsa
Wy don't you installed the engine up side down? I'm not saying you did wrong ;the job look extreme nice ,but I think would be easier no?
just woundering becouse I'm thinking in do the same setup as you did with the DA 85 but w/ GREEVES PIPE insted.
let me know

WinginIt

My Feedback: (17)

Looking good Tero.

Do you expect any problems with air flow to the carb since it looks like it might be drawing air thru the fuse? Don't know if that is a bad thing or not, was just wondering.

tetsa

If the engine was installed up-side-down, I'd have to cut quite a lot of cowling away. I like to keep the cylinder hidden as much as possible.

About the carb sucking air from the fuse: I see no problems with this set-up. I have much bigger engines getting their air from inside the fuse and they work just fine. Usually the air inside the fuse is cooler that the air inside the cowl, so theoretically the engine should produce more power when carb gets it's air from the fuse.

Damo260

Here are a few pic of my 260 with a DA100 MTW Stainless-steel header, 70mm drop with KS 1060 tuned pipes.....

Damo

Giln

Looking the business Damo.
Thanks for the pics.

Damo260

Thanks, I should have it finish by the weekend for it maiden if all goes well…………
Damo

Damo260

What is the best way to do the elevators & rudder hinge to keep the aluminium tube in position[sm=confused.gif][sm=confused.gif]
Thanks Damo

RTK

My Feedback: (1)

I use button head screws, looks nice too.

Damo260

cool thanks
Damo