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Building Tips and technical articles. => ARF'S => Topic started by: Ron Varnas on April 19, 2008, 07:27:06 PM
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Hi all,
What's a good starting out line-length for a Vector 40 ARF eyelet to eyelet?
I'll be using a re-worked OS FP 40 with tube muffler and
.015 dia lines.
;)
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Hi all,
What's a good starting out line-length for a Vector 40 ARF eyelet to eyelet?
I'll be using a re-worked OS FP 40 with tube muffler and
.015 dia lines.
;)
Hi Ron
That will depends on several factors, how fast-slow you fly, how much the plane weighs etc.. but a good start point would be 62 ft
Randy
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Hi Randy, ok it's a good starter, thanks.
*ps I'll be calling you soon
RonV
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Well, let me add something here. I'm not an Expert by any means, just a retread at it with great pleasure for the last five years. Perhaps my experience, however, is closer to Ron's than Randy's. I'd start off with 60 foot lines on the Vector, at least for shake down flights. If something is out of trim, the shorter lines will make it less likely that the plane will come in on you. Or if it comes in, it'll be easier to back up and maintain tension. Also, initially, the shorter lines will make coming over the top on wingovers less demanding on the set up. A poor over rich engine run will also be easier to handle on shorter lines. After the initial trimming the longer lines would probably be closer to ideal.
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Hi Ron V.,
62' eye to eye and 60' eye to eye is about 2/10s a second in lap times. Unless you built the Vector as a pretzel, and the FP 40 sounds like a 1 cylinder John Deere when you launch it, you should be just fine on 62' eye to eye.
If anything, miss the needle a click or two lean for the first flight, not too much, but a touch on the fast side. Faster airspeed will mask a lot of trim issues, but might save the plane early on. Once you get it pretty level and stable, you can start to refine the trim and slow the plane on down. On 62' eye to eye, I would say the Vector 40 can easily fly in the 5.3 to 5.4 lap times if decently trimmed. Wings level, and tank trim first. Those are the two worst enemies to a retread if they are not dealt with early on, IMHO along with proper CG. The CG should not be a real issue with the Vector 40 unless something has drastically gone wrong.
Bill <><
Bill <><
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I disagree, in my experience there's quite a difference in feel between 60 and 62 feet. Speed difference may not sound like much. But, for me, in practical terms, felt quite different.
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Hi Bill & Dennis,
Good points there for sure :D
I'll go with the 62's as here in OZ we are not bound
by the line dia. (ama rules) I can use the 'laystrate'
we used here years ago, it's most likely .012 & a lot
of guys still use it on 600sq ST46 size models.
I wouldn't class this 40 FP as a John Deere as
Scott Reise built it ,as such it's a jewel ;)
Bill, did you ever get to build the Genisis 35 ?
RonV
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Hi Ron,
I did not build the Genesis 35 per se. I modified the fuselage to a bubble canopy, and added a couple inches to the WS. I used an FP 40 from Byron Barker and it flew excellent!
Bill <><
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I disagree, in my experience there's quite a difference in feel between 60 and 62 feet. Speed difference may not sound like much. But, for me, in practical terms, felt quite different.
Well, Dennis, there is nothing to *disagree* over. The designer of the model said '62 and I said 62' for the first flight for obvious reasons. As I said, unless someone cannot build (assemble) or the engine is toast, then starting at either length is a moot point, really. You HAVE to start some where, and you have to trim the plane. That can be done as easily at either length as it can the other. I can find it hard to believe that anyone can tell a difference of 2' in line length on the FIRST flight, and you have not flown the model before. Changing line length AFTER the model has been trimmed can provide a noticeable difference in feel, but BEFORE it has been flown?? Plus, it is REAL easy to cut off length while trimming, but petty hard to add length without getting another set of lines.
Bill Little <><
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No biggee, of course. Simply a caution. I've had one or two birds that showed weirdness on the initial flights. A misalignment not caught or a wing warp, for instance, or an engine mounting that made for slight offset the wrong way. Shorter lines make it somewhat easier to deal with big trim errors like this. IMHO. I'm talking about the first shake out flight. I've got an assortment of lines now, some of which are kept strictly for back up. So it's not a problem for me to choose shorter lines when trying a bird at first, a set that might be replaced by lines that are longer. I've had more than one bird that felt very different with a line length differential of 2 feet. Also, 62' eyelet to eyelet is close to 64' handle to center of plane. Very different from 60' eyelet to center of plane. The AMA method of measure. Never thought much about the difference until one of my birds sat next to a friend's bird. I was using my typical 60' lines, eyelet to eyelet, my friend's bird looked like it was on short lines to me, big difference. I asked him why he was using such short lines. Well his was measured eyelet to center of plane. Accurately classified as 60' lines when using the AMA standard. An appropriate length for the 35 sized plane he was flying.
.
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Hi Dennis,
Line length does make a difference in flying a model of course. Trim is different when you change line lengths, for sure. And yes, when you go to the NATS they measure from C/L of handle to C/L of the plane. So you are correct, a set of 62' eye to eye lines would measure about 65' on a Vector ARF at the NATS.
I have heard Ted, Brett, and others, mention that flying a precise pattern is actually much easier on shorter lines (to a point, of course).
I have also heard for years the old adage of 60' lines for a 35 size model. But, as we both know, that is just an arbitrary number that will not get you in trouble, usually.
Bill
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Big Bear, reread your last post. 64 foot lines eye to eye will be measured longer than 65 foot center of plane to center of handle at the NATS or anywhere. Now don't yell at me as I make the same mistake at times. I think it was last year or the year before when guys had to cut lines to meet the rules. Another is when the guys find out that the safety thong has to be pulled also. I think several never even got close to lifting the weight. But, as far as trimming planes I think Windy, Bobby, Billy andquite a few others say the important trim is when you learn how to bench trim a plane. My Fancher "Doctor" did not take any trimming at the field as I followed Ted's advice to the letter. Have fun, DOC Holliday
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Big Bear, reread your last post. 64 foot lines eye to eye will be measured longer than 65 foot center of plane to center of handle at the NATS or anywhere. Now don't yell at me as I make the same mistake at times. I think it was last year or the year before when guys had to cut lines to meet the rules. Another is when the guys find out that the safety thong has to be pulled also. I think several never even got close to lifting the weight. But, as far as trimming planes I think Windy, Bobby, Billy andquite a few others say the important trim is when you learn how to bench trim a plane. My Fancher "Doctor" did not take any trimming at the field as I followed Ted's advice to the letter. Have fun, DOC Holliday
Sorry, Doc, a typo. 62' eye to eye (like I had been saying, and Dennis said) will come out around 65' C/L to C/L. I didn't proof read it close enough...............
I do agree totally with the comment on bench trimming!
Bill <><