|Jan 27, 2012, 12:26 PM|
Joined Jan 2011
I built FSW full fuse plane by someone on here. It was the nasa one, x-37 or something along those lines. He had a long thread about getting the CG and everything right as its hard with planes of this style. Also had some bad pitch tendencies depending on throttle. Think the way he solved it was by adding a cheap gyro to the elevators,and that helped it out a lot.That might also work for the guy having issues flying in the wind.
|Feb 22, 2012, 08:27 PM|
Joined Dec 2010
i am making one too, if you care to, here is the reason why it broke and have taken some effort to make the concept clear
wash out/ Wash-in Due to Flexure
Disclaimer (This discussion pertains to RC aeroplanes and esp foamies, therefore aeroelastic tailoring has been left out of the discussion)
When a swept back wing flexes due to less of torsional rigidity the incidence at the wing tip reduces , effective lift production is concentrated inboard of the wing (See image) wing tip therefore looses lift, the centre of pressure moves forward and aeroplanes pitches up, if the tip lift loss is high, she will pitch up and yet loose altitude
How does this happen (You need to have some imagination , easier way is to fold a paper and see)
When a swept back wing flexes under load, all chordwise points at right angles to the main spar are raised to the same degree, see image two, the points A and B rises through the same distance and the points C and D rise through the same distance but through a greater distance than A and B.Thus C rises further than A and there is a consequent loss in incidence at this section. This effect is termed, ‘washoutdue to flexure’, and is obviously greatest at the wing tips. It is most noticeable during high g manoeuvres when the loss of lift atthe tips and the consequent forward movement of the centre of pressure causes the aircraft to tighten up in the manoeuvre. (very applicable on faomies).
Now washout is structurally not dangerous, because wing tip is unloaded of high lift
Wash-in Due Flexure on a swept forward wings (Like su-47 berkut)
In a swept forward wings if you see the image above due to flexure the wing tips will produce more lift, this will overload wing tips and it will break away clean . (http://www.rcgroups.com/forums/showp...60&postcount=9), you can see how cleanly it has broken, it is due to wash in due to flexure
|Mar 21, 2012, 10:57 AM|
Joined Nov 2011
I agree pusher jets Rule.
I am just curious if a 1800KV motor would be enough for it. I am making in 5mm depron, as this is the only size is available here. I have previously made F-16 & SU-37 out of it. I had 100% success rate even in windy flying conditions. But I has 3700KV motors on them. Since, these motors are already hooked on planes, the only available in my stock is 2209/1800kv (RC Timer brand). Kindly let me know.
|Mar 21, 2012, 06:03 PM|
That 2209 will work OK, but you can still only use a 6X4E prop (or maybe bump up to a 6X5E) due to the prop opening. The plane will fly, but not with authority.
Oh, and I now carry the motors and ESCs for these bad boys on my site. There's individual pricing for the motor and ESC, and then there's a combo as well. And I have APC style 6X4E props too.
|Aug 11, 2013, 10:35 AM|
Looked great, crashed great..
I've had this plane for a while now, returning to it from time to time. Although I've never had it in the air more than a few minutes I have yet to completely give up on it. If I had to guess I'd say that my CoG is completely out of whack. I've tried putting the CoG where the plans call for it and then tried moving it forward but the plan still acts, I think, like it's overly tail heavy. When launched it noses high, starts to slide sideways and then will usually end up rolling over onto its back.
Anyway, after having the nose crumpled yet again I decided to take another swing at this and try something different. Functional canards.
I cut the old nose off, traced some new replacement pieces, toyed around with a few different sizes and shapes for the canards and set about putting my plan into action.
First thing I did was change the programing of the two existing servos to dual-aileron mode. Then I dropped in a spare 9g servo towards the nose for the canards. To make the canards I used some carbon fiber tubes, a spare control horn and a bunch of epoxy. Everything went together well and functioned correctly on the bench.
First flight - EXACT same thing. Nosed up, slide sideways, flipped onto its back and then nosed into the ground. Surprisingly no foam damage but the one side of the canard popped the epoxy from the carbon tube and was spinning freely so I couldn't reposition the battery forward to test a more forward CoG.
Frustrating... I really want to see this thing flying some patterns at my local field. Oh well, I've re-epoxied the canard and we'll try it again with a more aggressive forward CoG.
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