My plane is better than yours because,its smaller

So you got a hot plane, eh? Tell us why you think you're gonna be Top Gun this year!

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Big Dog
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Post by Big Dog »

All this talk about snow. I think I'll take the 35% Extra out for a spin this weekend. It was a chilly 77 today.
TheKid
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Post by TheKid »

WEll it flies!!!! We took it out today with a mild setup (about 400 watts) and it flew like a charm! Well maybe not. I throttled up, and the old man threw it. It started to dive for the weeds so I throttled cut the throttle for a second but it started going up again and i got back in it and i was in the air.

I needed a few clicks here and there for trim, but for the most part it flew just great. I would guess the speed to be somewhere around 70 mph. The problem i had with it was that it was WAY nose heavy. You can tell this about a wing because when you try to do a tight turn it will "bounce" through the turn. This is the wing constantly stalling and recovering. I learned this on this forum [:D]

So i took it easy just to get a feel for it. It does thee flipping between positive and negative G's just like the real deal which is sweet!! The rool rate is fast or faster, just ho wi like it! The plane yawed a little bit. I attribute this to a few things.

1) Lack of vertical area and moment (not far enough back)
2) I had the antenna stretched out to one tip, and that was the tip it was yawwing to, so i think that was producing a noticable amount of drag
3) The nose heavy condition was making it just not handle very well.

So i came home, cut out the old balsa vertical and made a bigger, longer one out of 4mm coro. I also moved the motor back a little and taped the end of the antenna down so that it wasn't making as much drag. It still was a little nose heavy at that point it was still more nose heavy then i wanted it, so i taped 1/2 oz of lead to the back. This makes it balance at about 19% of the MAC, it was at 15% originally. Hopefully i can get back out tomorrow and ring it out a little more. I don't know if this will happen because we have a wedding to go to

Also, for the record i switched the motor out. It now has a higher turn motor (less rpm/V). So i have a 7x4 APC gas prop on about 400 watts. If all goes well i'll probably upgrade to a 7x5 or a 6x5.5. Im afraid the 7x4 will be too slow for my taste
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Ed Kettler
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Post by Ed Kettler »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">the old man threw it<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Scott,

Are you going to let him get away with that?
TheKid
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Post by TheKid »

Ed, it's sad but true. I am an old man, and I threw it. Like an old man.
combatgoblin
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Post by combatgoblin »

Whats the red thing in the picture a flying candy cane?LoL
ZenManiac
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Location: Near Madison, WI USA

Post by ZenManiac »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by TheKid</i>
<br />Ed, it's sad but true. I am an old man, and I threw it. Like an old man.
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">
<font size="2">Long time readers of the forum will recognize Scott's habit of not looking to see whose name he's logged in to the forum under. [:D]</font id="size2">
sgilkey
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Post by sgilkey »

yeah, because my dork kid keeps hijacking my computer!!!!
TheKid
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Post by TheKid »

Well i took the plane out today for the 2nd and 3rd flight. It flies very well. The first flight off the day i was still a little nose heavy. So i took it back and did a few things (again made the fin bigger and added some more weight).

Went back out to fly with my brother as film crew. Launched and it was all over the place. Definately too far back. So i eased it around and landed. Walked up and found i broke the prop [:(!] that was our only 7x5. So we went back, i changed back to a 7x4, moved the lead further forward. And the flight went off without a hitch. On landing though the prop must have caught and it snapped the shaft of my motor [:(!] good thing the company i got it through offers a 1/2 price replacement policy...

Heres a link to a couple videos. You can't see much besides the launch in the first video. In the second you see one turn and then the memory card was full [V] but it chhanges direction well like a real russian wing, and with a little bit of messing around im sure it'll be a real sweet flyer

http://www.rcgroups.com/forums/showthre ... st11278388
TheKid
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Post by TheKid »

Hey all, i posted a couple more videos. Ones where you can actually see it fly. Gilette, i know you're going to want to take a look at this. I think i found a good home for your 16/15/3...

And ed, i suggest you look. I don't know about you, but it sure feels like the battery isn't slowing me down too much

I still am getting the weird bouncing through the turns problem. My dad and i thought that it might be because it is a pig. So i put it on a diet tonight. I changed the whole power system, and now its 7 oz lighter!!! Only problem is im limited to a tiny 200 watts. I'm going to have to find a more suitable motor. Something inbetween beast (ARC 28-47-1.5) and wimp (cheap outrunner that im using). I think something in the 2 oz range and around a 2500 kv...
THend
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Post by THend »

Bouncing through the turns sounds like a CG issue. Move the CG back a tad. You do any of the climb high, dive straight down no throttle trim stuff to see what is going on? If dialed in, it'll dive fairly straight down to very slight pull out. If it tucks under or climbs out your CG is off. Just a thought.
TheKid
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Post by TheKid »

Yeah terry, i thought about that, and i've moved the balance point back a lot (like 25%!!!). I think its just too much weight for the wing to carry (300 sq and 27 oz) and still turn effectively. We'll see if/when i fly it tomorrow on the light power system though. If it still bounces then i'll know its too far forward

It is "hunting" a lot, meaning that when flying level it wants to go all over the place. This could be attributed to the balance point being to far back (my guess) or the servos not centering well (another good guess, dang HS-81s).

Im thinking that i'll leave this one how it is, nice and light. And get another one from fredericks around summer and make it a little bigger, maybe 50" span instead of 40 and then see how that one goes...

Thanks for the help terry, as a wing guy i know you've got good advice for me
Lee Liddle
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Post by Lee Liddle »

Brian, it`s pretty common for a "wing" with asymmetrical airfoil to bounce thru the turns like that if it`s nose-heavy or just plain heavy like you`ve already addressed, unless they are WAY over powered like the Russian combat planes of the Open B ships that Mike and Corey are flying.

O`d suggest a different airfoil like the Clark-YH and make the elevons about 20% of the cord. That way they don`t have to be re-flexed much to get level flight, and don`t need much movement to control pitch.

Even on a well balanced flying wing, if the elevons are too narrow and have to be deflected too much to control pitch, that can stall the back of the wing while turning and cause the "skipping" in the turns.

Overall, good job. Build another one, and keep us posted.
sgilkey
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Post by sgilkey »

I have zero experience with these wings, Brian did all the test and trim flying for the fleet he built last year. I've never flown them once, so I don't have a feel for what's going on other than from the perspective of "conventional" planes- this one's turns are "segmented", like a CNC cutter making an arc- rather than a smooth radius, it appears to be turn/stall/turn/stall very rapidly. It still turns tight, but you can see the rapid bouncing. So to me it looks like the wing is stalling which I think is just because of the weight/area. He tried moving the BP back and it became squirrely. I've seen him fly the full-size Russian wings tail heavy and it's not pretty. Especially when the fuel shutoff isn't working..... Anyway moving the BP any further back seems to degrade the handling from what he's told me.....

We talked about adding area, which could be done easily, this one has plenty of roll rate so a bit more span would be fine. I think this new lighter power system is going to perform really nice in terms of turns, he saved over 7 ounces. But he's at 1/3 the power so we think he's gonna find it a bit slow. We'll see...sleet storm last night so may not be able to fly for awhile, and he returns to school this weekend.

One other thing we thought about is the thrust line, which may be a bit high. He says it turns better negative than positive. With his engine (oops, silly IC boy) motor mount system, he can't lower the thrust line.
Lee Liddle
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Post by Lee Liddle »

I forgot to mention that. Yes Scott, you`re right about the thrustline. It`s best if it`s inline with the airfoil centerline. But if you can`t shift the whole motor, try a little up thrust. That will help. If it is requiring more "up" elevon to turn, which it sounds like it is, even though the whole wing is not stalling, the extra deflection on the elevons can screw up the airflow so much that it doesn`t turn right.

My theory is that the deflection causes so much turbulance at the back of the wing that the elevons stop working, which opens up the turn, then the airflow returns briefly to increase the turn for a moment until the turbulance returns, which opens up the turn again...repeat...repeat until you let off the stick.
M. Gillette
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Post by M. Gillette »

Sweet!! I like it!! You get it De-Bugged and I'll do one too. I'm still looking for a home for the Mega.

Where are you flying in the last two vids??
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