n00bs Gonna Build a Carden

[gareth.ky]

I think it will be a great freestyle airplane. I did some flying on the 26x12 and its much better. Much more like video's I have seen of the DA-85 powered airplanes out there. Good strong vertical, very responsive.

Unfortunately its been getting warm and feels like its sagging. I messed with the needles and tried to richen it up but there was no change. I don't see how I don't have enough area cut out of the front of the cowl. Like the Aeroworks airplanes have way less cut out than that and they fly fine. The motor is also making some funny rattling noise at full throttle. I sent the motor back to DA so we will see if they find anything. I think its like the bearings or something.

I have also been talking with Dennis and I'll be taking out the levels again to check some things on the airplane. Hes is a really helpful guy.So I'm hoping I can find some error in the build or the setup because my experience isn't jiving with his experience and the experience of other builders he has talked to. My mix percentage in yaw->roll is like 10% and it should be more like 1-2%. I need a Yaw->pitch mix and that should be almost 0. I'm just trying to find out why that is.

I'm going to be looking for surfaces not set to 0, stabs/wings not set to 0 and any up/down thrust that's in the motor mount.

[FlyguyXII]

gareth I would try taking a piece of 1/8in light ply and put it verticaly in the cowel slightly forward of the center of the cylinder head. I had a zdz80 cooled like this for a long time and never had any cooling problems.

[craig77]

thanx for that info bud!hope they sort out you DA!?I had a 50 do the same thing!it would be fine for abt5mins into the flight then just suddenly loose power!i tried everything with the cooling and nothing seemed to work!I eventually found out that the cylinder had warped due to excessive heat!this was quite pronounced in the really pink couloured head!it turned out that i was over reving the motor!it was installed in a EF 88" yak 54!she was running 7200 on a 23X8 mezlik on a mtw tuned pipe!way to much!!hope this is not your case!(ie damaged the motor in its early life)

looking forward to getting mine!

[gareth.ky]

Well, that may have happened when I had the cowl too closed off. It flew with the more enclosed setup for a few flights. On the 27x10TH prop there isn't much vertical penetration so the problem went unnoticed. I'm sure DA will give it the once over and see whats up.

[Neil4]

Gareth.Ky, Did you figure out the yaw/pitch coupling problem? Was any of the incidences on the flying surfaces off? Curious to hear because you don't usually hear about that bad of a pitch/coupling problem on a 260, let along a Carden. Extra 260's usually have a little of the pitch/coupling when the rudder is applied but not as much as you described.

Keep us posted,

Neil

[gareth.ky]

We I finally got a new battery in my angle pro. Keep in mind that these are throws i have come up with by feel so far. Per instructions from Dennis I re-did the Yaw->Pitch mix so that if fly's hands off in knife edge. This resulted in needing only 5% mix for right rudder and 0% for left.

Rudder throw is around 23 - 25 degrees (40% D/R). Its kind of hard to measure with a protractor.

Elevators throws are 6 degrees up and 7 degrees down (22% D/R). The Yaw->Pitch mix of 5% on right rudder gives a 0.3 degree deflection of the elevator at full rudder.

Ailerons are about 18 degrees each way (50% D/R). With the 10% Yaw->Roll mix I measured 1.2 degrees of deflection at full rudder.

All surfaces report less than 0.5 degrees off of 0. I think that's probably within the fudge factor because the garage has a 5 degree slope and the airplane was oriented across the slope.

That's the raw data. I'm surprised I use so little elevator throw! I'm also surprised at how small those angles are, it doesn't sound like much.

[gareth.ky]

I called DA and the motor got a clean bill of health. No problems found so I guess its time to consider baffling and cooling.

[craig77]

well it least thats some good news thenmy cardens should arrive next weekcan't wait!!!

[gareth.ky]

I like it.

Motor worked like it should. The funny noise is gone. I moved the pushrods in one hole on the arms. Using the carbon tail tube the CG is right where it should be. Coupling seems to be reduced and mor closly related to KE coupling.

At 10 degrees of elevator it's really fun to fly. It hovers really well, super light.

More after practice tomorrow.

[Jim T]

	Quote: Originally Posted by gareth.ky
	I like it. Motor worked like it should. The funny noise is gone. I moved the pushrods in one hole on the arms. Using the carbon tail tube the CG is right where it should be. Coupling seems to be reduced and mor closly related to KE coupling. At 10 degrees of elevator it's really fun to fly. It hovers really well, super light. More after practice tomorrow.

Hi Gareth,
I'm curious what you've ended up with for servo arm length? I'm going to be building this same plane this winter with a DA100. I'm going to set it up for IMAC only.
By the way, I've gotten a ton of great build info from your thread.

Tnx, Jim

[gareth.ky]

Jim, I am at 1" on the arms now. Thanks for the appreciation of the thread, good feedback makes it worth doing!

[gareth.ky]

Today's Lesson: Don't fly with a cracked spinner.

The bolt that holds the spinner on didn't break when the spinner self destructed. So it became a big weight and unbalanced the motor. The firewall broke free of the motor box and the prop hit the cowl stopping the motor.

I'll have it repaired before I go to sleep tonight BUT I need a new spinner, prop, muffler and cowl.

So, oddly enough, the motor box failed at an epoxy glue joint. The dowel pins got sheered off. It broke up one side of the box but the other was intact. So the lightened box is not as weak as you might think.

The repair will be done with 100% M100XF Mercury CA. In fact I think I'm pretty done with epoxy. I'm putting the bits back together and then I will plate the sides with 1/8" ply. I had 8oz of weight on the nose so added weight is not a problem.

[eagle1]

ouch Gareth!
what cracked the spinner to begin with? and you knew it was cracked before you started the engine or did it all happen too fast?

[gareth.ky]

It's been cracked for maybe 15 flights. I don't really know what cracked it. The crack was not getting any worse. People have suggested that I over tightened it. I held off on getting a new one because they cost $120.

Now its like this: cowl $90 + prop $80 + muffler $160 + spinner $120 = $450

Don't fly with a cracked spinner.

For this weekend I have a prop I can use and Greg is going to loan me a muffler. So all I really need is the cowl, spinner and enough time to fix it all.

The planking on the motor box added 5.2oz to the nose.

[craig77]

damn bud!sorry to see that!Iam nearly done with my 40%er