hobbydude214

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Hello Everyone!

I recently purchased a 89" Carden Aircraft Company Extra 300/s. It is equipped with a DLE 55, for Aileron and Rudder HS-5645MG and 2x Elevator HS-5625MG. This is a used airplane kit built by a well respected pilot and builder in the area. Before taking it up for the first time yesterday I had gone through it checking over every bit of what I could think of (All servo leads, fuel tubing checking everything tightened down, any slop in servos, etc)

Fuel is 90 octane no ethanol mixed with Stihl Ultra HD at 30:1, spark plug is of unknown age. I had the help of some experienced members getting the engine ran up. We had some trouble getting the DLE 55 to idle properly, it would fire up fairly easily. It seemed to load up at idle and would transition to full throttle with hesitation but get there. We tweaked the low end by about 1/16th turn rich then lean with a few adjustments either way and none seemed to get it in the range where there was a confident low idle. Finally got it to idle and a slightly higher speed and flew for the first time, a beautiful flight with a great landing even in 15mph crosswind. The second flight didn't go as well on landing, I made about 4 passes with the idle trim just too high in fear of it quitting. the 5th pass I dropped the idle a few clicks on the trim and it started to float right in nicely but about 10ft over the field the engine quit, luckily it glides well however with the cross wind I needed some decent correction and it almost tumbled, but landed safely. While in hindsight I should have stopped for the day and worked out changing plug, switching fuel etc, and not risked the plane, excitement got the best of me.

If you're with me still and reading this Thank You, I know it's long, and I'm trying to provide as much info as possible. The left Aileron was stripped when we got out to the plane, which likely contributed to the hairy landing scenario aside from the engine quitting.

I have decided by the suggestion of one of our members to change the spark plug, ordered a NGK cs6, and change oil to Redline Racing Oil. If you have any further things to check out on the engine, suggestions are quite welcome. I've seen posts about the carb gasket, cleaning etc.

My second question is about the servos, I'm in a position now where I either get a couple gear kits, and replace both the aileron servo gears, only 1 stripped but might as well do it in pairs. Or consider new servos, I know some of the newer Extra's of this size are saying to go to 400oz/in which seem like some very very good servos. I'm not planning on doing some extreme 3D with this as of yet, and if in the future it's something I wanted it to do, I would reconsider different equipment on board.

From all the research I could find on forums related to this airplane, hence many 10 or more years old, I see many people putting similar if not smaller torque servos in the plane.

All suggestions welcome, and thank you in advance!

speedracerntrixie

My Feedback: (29)

Ok first let’s talk servos. I have never been a fan of the Hitec 56xx series of servo. IMO they are too slow and don’t center well enough for use on a top shelf aerobatic airplane such as your Carden. Since you already have servo arms ( hopefully aluminum ) for Hitec, my suggestion for a Hitec servo that is a great bang for the buck is the 7955TG servo. I have used these myself on a 40% Extra ( 2 per aileron ) and had zero issues with them the 4 years I owned 5he airplane. If you are open to a different brand, the MKS HV1220 is a wonderful servo. I currently have a set of them in my 35% Edge. Again a titanium geared servo like the Hitec 7955 but a reasonably priced high voltage servo. This allows the use of lipo batteries which not only give you higher voltage but a battery tech that will keep the voltage constant while under load. Of course you will want a smart switch such as a Zepsus that you can use dual power inputs to your receiver. All of my new builds as of 3 years ago are going the high voltage route and seem to feel just a bit more solid in flight.



Now the engine. Every used engine I buy always gets a carb rebuild before I fire it up. Carb kits are cheap and it can be done in less then an hour. There are many videos on YouTube showing rebuild and metering needle height adjustment for Walbro carburetors. While on the fuel system, I highly suggest a felt clunk and a 3 line system. Using a dedicated fueling line reduces the debris getting to the carburetor. Even with a felt clunk, use a good quality lawn equipment fuel filter. Hobby fuel filters don’t get the really small particles that can mess up a gas carburetor. Going to a CM6 plug is a must, gap the plug to .026. I would hold off on checking the Reed block for straightness as a last resort as that was an issue that got resolved a while ago. However do make sure you have no air leakage. I suggest getting rid of the carburetor/reed block retaining bolts and replace with a couple 10/32 studs. The bolts have a habit of working loose and if you over tighten them to prevent that, you can easily distort the Reed block. A couple studs with lock nuts prevents both situations. I fabricated both my studs from 3/16 titanium rod and a 10/32 die. From what you describe I think your metering needle is not sealing and you are getting excess fuel at idle. Fairly common with Walbro carburetors. The rebuild kit and correct metering needle/lever height ( pop off pressure ) will fix that situation. Good luck and if you have further questions regarding that airplane don’t hesitate to reach out.

hobbydude214

My Feedback: (13)

Hi and thank you for all your advice! I'm currently running lipos with (2) 6V regulators for ignition and rx, the rx is an AR8020T with satellite. The Hitec servos you mentioned definitely seem like they would be a great step up, looks like they're out of stock until June, if I was going to wait for them, how do you feel about flying the current servos, with a gear rebuild of course, until then? I've found many forum posts from the mid 2000's and seemed like a fair amount of people used these servos, surely technology has come a long way, and budget could come into play. I got the plane at what I would think is a very good deal, and I know that with bigger planes, everything becomes more expensive.

Is this the correct kit for the carburetor?

speedracerntrixie

My Feedback: (29)

I would order the carburetor rebuild kit from Valley Veiw R/C that will take the guesswork out of getting the correct kit. Using your current servos. If I were going to do as such, I would set up your control geometry with a 2:1 ratio. What that really means is use a 1” servo arm and a 2” control horn. You can of course change actual dimensions as long as the servo arm is 1/2 the length ( or shorter ) then the control horn. This will increase force to the control surface but will also make the surface movement slightly slower. I have a gut feeling though that your gear failure ( the fine pitched brass gear ) was more vibration related as the DLE 55 kicks out a fair amount of vibration. Aileron servos are hit the hardest when it comes to vibration. You may want to check other retailers for the 7955’s, odds are you will find a pair with a search.

Speaking about linkage geometry, you probably noticed the throttle being quite non linear and full throttle happening before full stick. To greatly help with that make a carburetor arm that is at least 1.5” and make your servo arm .5”. This will have you use +/-100% of the travel volume to get to 80% carburetor opening. That last 20% offers no power increase and reducing travel gives you a power change with each click of throttle. Then with a throttle curve in the TX you can adjust so that you have cruise speed at half stick.

Your RX/ battery setup sounds fine. It sounds like you are using dual batteries into the RX which IMO is necessary to get enough current to the servos. How are you powering the ignition? I suggest you take a look at the Tech Aero IBEC. It serves as a regulator and on/off switch that plugs directly into your RX. Remember to do a good range check each and every time you change any electrical item.

hobbydude214

My Feedback: (13)

Thank you for your thorough responses!!

I've scoured Valleyviewrc.com it doesn't appear that they offer the carb kit, they do have full replacement carbs, reed valves, and various other parts, just not the rebuild kit which I think is K-20 WAT.

I believe you're a psychic on 2 levels (haha), it was the brass gear on the Aileron, and the throttle was extremely non linear (Full throttle at about half stick, servo endpoints set way back, and even tried a throttle curve). I will inspect and follow your instructions on the linkage setup on that, any advice on making a longer arm for the carburetor?

As for the Aileron servos, since they are hit the hardest, how do you feel about swapping those out first and getting to the rest when I can? Pending the servo search.

My battery setup is a 2000mah 2S LiPo with regulator to the RX and 2000mah 2S LiPo with regulator to the ignition with remote ignition cutoff. I also have smoke on this airplane which I have not gotten a battery for yet.

speedracerntrixie

My Feedback: (29)

LOL, Sorry no super powers other then I’ve been at this for a while. Yes you could just replace the aileron servos for now and be fine. About your battery setup. For a 55cc airplane, 2000 is a bit light for the RX and a bit overkill for the ignition. That said, if you went into the RX with both and then pulled the ignition power out of the RX you would have a pretty much ideal setup. I will again suggest the Tech Aero IBEC to run the ignition as it has filters to keep the nasty stuff out of the RX. Valley View will have the DLE version for half the price but I have no real time experience with it. Not too much of a worry there as the ignition frequency is well below 2.4 ghz. The worry is that the ignition noise can get into servo leads. Good news is the Hitec servos you have and plan to get have twisted leads that help eliminate the chances of that happening.

The carb kit will most likely require a phone call to Valley View. Owners name is Tom. I make my throttle arms out of fiberglass plate. You could also make 5hem out of aluminum or even a metal servo arm. I attach with a single 4-40 through the hole in the factory arm and backed up with some JB weld after scuffing the parts. You can also correct the carb arm differential angle while making the new arm.

hobbydude214

My Feedback: (13)

I think I'll do just that for the ailerons. I'll probably enjoy them so much I'll be very enticed to put them on the rest of the plane. So if I get the Tech Aero IBEC would I run the batteries (2x 7.4V 2000mah) in parallel then to the rx, with the Tech Aero from the rx to the ignition? Which would give me 7.4V 4000mah at the rx.

I found this article on the fiberglass plate and figured I'd share with anyone following this thread. https://www.modelairplanenews.com/cu...-throttle-arm/

speedracerntrixie

My Feedback: (29)

You would run your batteries to the switches then regulators and then into the receiver. Switches before regulators as the regulators draw current whenever the battery is hooked up to them, if you run out of ports in your RX you can power in through a Y connector. Just install the Y to your throttle servo and plug a switch into the other side of the Y. If you have a battery or regulator failure you will have a redundant system that won’t end up in a crash.

You may find yourself running out of available ports in your RX though with the additional battery input, an IBEC and smoke pump. A warning about smoke, yes it’s super cool but will add a couple pounds of weight but more importantly, the smoke oil will get everywhere including under covering.

hobbydude214

My Feedback: (13)

Thoughts on MKS 1220? Titanium gear, faster and more torque (also able to go up in voltage from 6V) than the HS-7955TG

speedracerntrixie

My Feedback: (29)

I have them on the elevators of my 35% Edge. So far so good. I tend to put a lot of effort into my builds and keep them for several years. As a result I’m pretty picky about how things work.