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Post by akeasy3 on Apr 8, 2012 1:36:59 GMT 1
Hey just added ailerons to my cub. First post, but been reading a lot into how I should do this.
I bought my new cub last fall and she was shelved after running her into a post. I did some patch work a month ago such as gluing the tail back on and the battery cage. I recently had to scrap the body with just the eppinage, wing, electrical, and motor.
I decided to build ailerons into a new wing. I used the normal park zone servos and put them flush into the wing about an inch back from the leading edge and about 10 inches from the fuselage. The ailerons are 10 inches by 1 1/2 inch 8 inches from the fuselage. I did not want to make them too large. My intent was to have an easy roll when she turns.
I weighed heavily on flattening out the wing and after a lot of research (I'm surprised I got any work done this week) I decided to add a small steel bar 2 inches from the leading edge with the help of a blow dryer and some hot glue and heavy books she now nearly flat with a slight barely noticeable bend.
I decided to try her out last night just to see how she handles. There's still way too much snow on the ground at the parks so lately I have been going to a nearby high school. I chose a park since I figured I needed as much room as possible. She seemed a little sluggish but worked just as I hoped.
My concern is I did not upgrade to a brushless motor. I usually enjoy powering back and floating over snow berms and hills. With the wing flattened is more power needed to just stay in the air? I really haven't gotten to do a good test flight yet as for some reason the weather wanted to break the snowfall record this weekend. Anyways have a good flight
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Post by realbob on Apr 8, 2012 3:33:44 GMT 1
Nice! DO yoiu have any pictures to share?
Where are you located to still have snow?
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Post by toff on Apr 8, 2012 22:13:03 GMT 1
Akeasy...welcome, and in answer, nope! The SC will fly quite happily with the stock motor, with or without ailerons. However....are you using the old Nimh batteries, or are you using lipos? I ask becuse the battery drain on the Nimh will be quite high ( they are only 8.4v), as opposed to the 11.1v 3cell lipo, which will shrug off the extra load. Fro the sound of the 'sluggish' test flight, I suspect Nimh...Lipos may have to be the next upgrade! And, if using the original RX/esc , I'll point out that although it may be fine, the electronics are not that great, and no-one really knows what it's real potential is! (We think it has a 13A esc, but don't know if it has a BEC, and if it does, what it is rated as - A BEC (Battery Eliminator Circuit) means you can still control the plane even if the motor dies) If it happens to you, flying stock, it may not provide enough amps to power your servos.
Sorry if it sounds a bit much, but this hobby seems to thrive on information overload ( Unless you are a priest of the holy electrode like flydiver.)
Hope you have great flights with it, and find 4 channel flight as rewarding as me.
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Post by realbob on Apr 8, 2012 23:02:48 GMT 1
HI toff,
I think there is BEC since when my motor goes out I still can control both tail servos...
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Post by toff on Apr 8, 2012 23:39:06 GMT 1
Hi realbob (My littleun loves your avatar!),
Point is, how many servos are you running? 2? Thats what the SC was designed for. Rudder and elevator. Akeasy is running 4 ( rudder, elevator, aileron, aileron.) The RX/Esc on the stock was only designed (as far as we know) for 2 servos, hence my warning regarding the exrta strain on the BEC on the Stock RX/esc unit.
I personally ( and, I think, many others, have requested this information from horizon hobbies, but you never, ever get a reply.......)
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Post by realbob on Apr 8, 2012 23:58:26 GMT 1
oH!!! Now I get it! (thanks for the avatar!!). But correct if I am wrong, if BEC cuts off the motor, if the servos for the 2 extra ailerons are not touched, you think it is still drain battery to those servos? Sorry for my ignorance!
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Post by toff on Apr 9, 2012 1:49:29 GMT 1
Realbob, anything connected is a drain, even if not working (think about your tv, tivo box, etc on standby - still using electric, even if not in use - same applies to the plane, but limited power source - battery. 4 servos drain more than 2, and if it's an 8.4v battery....faster than a lipo. Basic maths. (about all I can do, ask flydiver -I'm as thick as a plank! but, Ive got this 2+2 stuff nailed! However...2+2+2+2+=shortage of amps? Ebola? Umm, dunno, ask fly, he's clever... He knows!
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knadams
Flight lieutenant
Posts: 48
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Post by knadams on Apr 9, 2012 12:58:25 GMT 1
i have done the same thing but brush less and it definitely has a higher stall speed so i do think you need more motor.
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Post by flydiver on Apr 9, 2012 18:52:41 GMT 1
Just flattening a wing does not change the loading or the stall speed since the wing loading theoretically is the same. There IS a bit more drag now with the aileron gap, extra servos, and the foil is compromised a bit. That does change the stall speed a little.
The real reason for increased stall speed is most aileron conversions end up adding a bunch of weight with heavier motors, battery, decorations, etc. THAT changes the wing loading.
BEC:
The BEC IS what feeds the servos and RX their power. They have a maximum rating. As you add servos to a plane the increased load is placed on the BEC. All ESC (with BEC) can handle 2 servos, generally can handle 3 servos, but once you get up to 4 servos you are definitely pushing your luck.
If you are lucky, noting happens > you get away with it. LOTS of people do this.
If not lucky > BEC overloads > shuts down (or fries-depends on the brand an quality) > no control at all > crash. This can happen to anyone and happens more easily to Spektrum users, a condition called BROWN OUT. Newbies learn this the hard way when their brand new converted Cub takes off like a rocket, makes them grin ear to ear, then promptly looses all control and destroys their new pride and joy. Search the forum for [Spektrum + Brown out]-happens all the time.
Solution:
1. Stay within the limits of the BEC. The higher the amp rating of the BEC (note - that's NOT the amp rating of the ESC) the better. Small BEC are generally 1A, step up is 2A, better is 3A.
Switching BEC are superior to Linear BEC. Linear BEC are on most ESC under 30A and and ALL cheap ESC unless proven otherwise. If it does not specify switched or SBEC, it's probably not.
2. Get an aftermarket BEC, disable the on board BEC and power your servos and ESC with that. Superior solution but adds a little electronic complexity. Most after market BEC are at least 3A Switched and can handle 4-6 servos no problem.
3. Use an RX battery pack. That's how the nitro guys power their servos and the way it used to be done. That's WHY its called a BEC (battery eliminator circuit) since you are no longer carrying a 2nd battery specifically for the servos and ESC. The BEC circuit inside the ESC is providing that function via voltage reduction to a separate circuit.
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knadams
Flight lieutenant
Posts: 48
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Post by knadams on Apr 9, 2012 20:54:02 GMT 1
^^^ the weight is what has gotten to me..... but it still flies great for the few flights i have had. im also using a rx battery i dont want to loose total control
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Post by akeasy3 on Apr 9, 2012 21:58:47 GMT 1
Hey thanks all. I have The DSM supercub with a li-po battery. I took her up yesterday due to calm winds and clear skies. I will have to upload the videos this afternoon. It took some work to adjust my thumbs but I was very pleased with the performance.
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Post by rivergreenmachine on Apr 20, 2012 23:33:52 GMT 1
I'm adding ailerons ... quick question please:
What kind of tape is used to keep the aileron attached to the wing? thx
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Post by SCC on Apr 21, 2012 7:01:46 GMT 1
I'm adding ailerons ... quick question please: What kind of tape is used to keep the aileron attached to the wing? thx Not looked into it for a while, Blenderm tape used to be the popular choice I preferred using hinges. If I did not have any and I was in a rush, I would use the old trick of cutting up a floppy disc or the plastic milk carton.  |
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Post by toff on Apr 21, 2012 8:01:54 GMT 1
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Post by rivergreenmachine on Apr 21, 2012 13:07:45 GMT 1
Thank you for the info on the tape. I'm in USA, so I'm off to Home Depot to search their inventory.
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