Sweet Vee question

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ronin4740
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Sweet Vee question

Postby ronin4740 » Sun Nov 19, 2017 8:26 pm

Just maidened the Sweet Vee I purchased from a forum member. Set the CG to the recommended 2 1/16" location and as, over three flights. we got closer to getting the engine on the pipe the Sweet Vee went from flying pretty neutrally to feeling pretty nose heavy.

Previous owner states that CG was 2 5/16th. Just wanted to check with other owners and see if that seems like a pretty standard CG point? Also do they tend to balloon when the power is off? We're wondering if it's a thrust angle thing causing the "nose heavy" feel as well.

Otherwise maiden went pretty well.

Thanks!

Chris
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KRProton
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Re: Sweet Vee question

Postby KRProton » Sun Nov 19, 2017 8:37 pm

Hey Chris!

Yes, my Sweet Vees both ballooned slightly on power-off. It was worst immediately after power was removed/throttle cut (yes, a down-thrust issue). I added in about 3% down elevator mix to off throttle and that fixed it. Never thought about it again.

As far as C.G., sounds like you've read my account elsewhere. I stand by my figures and though, I feel my other planes are faster, I did fly my fastest time with a Sweet Vee!

I know there are many Sweet Vees out there and hopefully some of the pilots more experienced than I will chime in. I will say that I absolutely loved everything about my Sweet Vees flying and ground-handling characteristics (one sold, the other caught up in a mid-air).

Tim


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Re: Sweet Vee question

Postby ronin4740 » Sun Nov 19, 2017 9:03 pm

Tim - I may have read your thoughts on CG elsewhere but I'm at the age where I have a pretty good case of CRS - would you mind refreshing my memory here or point me to your account?

Good to know about the ballooning. Thought I was going a bit nutz...

Chris


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Re: Sweet Vee question

Postby KRProton » Mon Nov 20, 2017 6:00 am

Hey Chris.

There was some discussion on Sweet Vee C.G. and I found it here;

viewtopic.php?f=1&t=5554&start=30

It begins on page 3 if the link doesn't take you there.

Of course the C.G. And throws work together and I don't have immediate access to what my throws were. I think I have them documented on my PC (all the way over in a spare bedroom - too far to walk right at this moment :lol: ) which I can retrieve later today.

Tim


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Re: Sweet Vee question

Postby ronin4740 » Mon Nov 20, 2017 12:02 pm

Thanks Tim. Will move the CG back a bit and try again this weekend down at Crows Nest.

The thing that confused me a bit on the third flight was that I really had trouble getting the plane in the air and then keeping the nose up. Was holding full up elevator and the plane was barely climbing. It was bad enough that I killed the engine before it became a speck on the horizon... As soon as I cut throttle the plane responded normally. Didn't do that on the first two flights but they were slower...

I can't easily get any more throw than I had out of the VTail... The third flight's takeoff was done at full rates and the up endpoints are already set to 125% in the radio. It looks to me like I have plenty of up elevator though so I don't think more throw is the solution.

If it does it again with the CG back then I guess I'll assume the Tactic servos are the culprit for some reason and swap them out for Futabas. On paper the Tactics have better specs but maybe they just don't like the amount of vibration the Nelson engine generates. They work great in the Quickie though!


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Re: Sweet Vee question

Postby KRProton » Mon Nov 20, 2017 2:31 pm

Hey Chris.

On my Sweet Vees the elevators were rather stiff. One was really bad. I purchased them second-hand (but unassembled) from a friend. They were not the CMAD Sweet Vees.

Anyway, one elevator was very rigid and even squeaky where the torque rod entered the resin that I believe serves as a bearing. What I did was turn my soldering iron up to "11" and touch it to the torque rod just long enough to soften the resin. I moved the elevator up and down and that seemed to loosen it up noticeably. I followed up with a drop of oil where the torque rod entered the resin and that helped.

Also, maybe slip in a piece of medium-grit sandpaper between the ends of the elevators and the stab to remove any residual fiber that could be causing interference between the ends of the elevators and the stab.

Finally, I've used those Tactic TSX25s in MANY planes when I worked at Hobbico - but only sport electric stuff and .40 - .60 cu in glow-powered stuff. I also had them in one of my Quik-V6s. I do notice free play in the output shaft for the servo wheel/arm. I have no real basis for saying this, but my intuition just makes me not trust them for a Q40 plane. Simply, I trust the name Futaba over the name Tactic when the stakes are really high like they are in Q40.

As you probably know, the Futaba S9650s and the Tactic TSX 20/25s are a direct, drop-in replacement.

Tim
Last edited by KRProton on Mon Nov 20, 2017 6:14 pm, edited 1 time in total.


stoned
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Re: Sweet Vee question

Postby stoned » Mon Nov 20, 2017 4:47 pm

Hello Chris
I have flown the model that you now own. The plane was balanced at 2 5/16 and had no bad habits.I recommend the futaba 9650 servos for this plane. Dean Stone


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Re: Sweet Vee question

Postby ronin4740 » Mon Nov 20, 2017 10:28 pm

Thanks for the input Dean! I may yet switch to Futaba servos...

Not sure what you mean by free play around the output shaft Tim - did yours turn slightly without any resistance from the rest of the gear train or does it wobble/move front to back in the hole or...? I'll check mine for weirdness tonight while I'm setting CG back to 2 5/16 or so.

Chris


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Re: Sweet Vee question

Postby ronin4740 » Tue Nov 21, 2017 12:03 am

Moved the 700mAh LiFE battery back from right behind the fuel tank to behind the radio. Would have thought doing that would have gotten the CG to about the right spot but I still needed to add about 18g of lead tape to the tail to get the plane to balance at the 2 5/16" line I drew on the wing. My Great Planes balancer says it's nose heavy at that point and it balances on it at about 2 1/4".

I'm wanting to believe my fingers at this point but can add more lead to the tail after the next test flight or easily remove it as needed. Will probably take the scale out as well so I can keep track of how much weight I'm adding.

The plane is still .4 ounces under weight so this isn't a big problem. Still am kind of scratching my head with regards to how the previous owner got the plane to CG and legal weight - his Futaba receiver, servos and battery pack must have weighed a bunch more than my Spektrum receiver, battery and servos do.

Next planned hop is Thursday AM now as my builder/tuner friend is willing to go out and fly Thanksgiving AM. Hoping to get it dialed in and trimmed so I can try it on a three pole course Friday morning!

Chris


stoned
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Re: Sweet Vee question

Postby stoned » Tue Nov 21, 2017 7:09 am

Chris
The previous owner flew this plane with jr radio gear. I think he used 3421 metal gear servos .


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Re: Sweet Vee question

Postby ronin4740 » Thu Nov 23, 2017 2:55 pm

Flew a couple of test hops this morning and am happy to say that the Sweet Vee flies great with the CG set at 2 5/16"

Heading to California tomorrow to get it onto a three pole course and try to dial it in along with two of Jim Lime's Phoenix quickies.

Next I'll have to learn all the intricacies of tuning a Nelson engine...

Thanks for all the input gents!

Chris


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