Author Topic: Bent NVA (Read 2881 times)

Joe Ed Pederson · « **on:** August 09, 2018, 07:53:20 PM »

As my Carl Goldberg Cosmic Wind rolled to a stop on a grass landing it flipped over and bent

the ST .46 NVA a little (about 5 degrees). At home I bent it back as best I could.

Is it a waste of time and an act of futility to try to straighten a slightly bent NVA? If it is futile, I may switch to full body models to keep from going broke buying NVAs.

I've thought of putting a piece of 1/8" plexiglass under the engine mounting bolts (control line handle side) to stick up higher than the needle valve and hopefully protect the needle valve in next inevitable crash or flip-over. Is the plexiglass a good idea?

Thanks,

Joe Ed Pederson

Ken Culbertson · « **Reply #1 on:** August 09, 2018, 08:14:13 PM »

Quote from: Joe Ed Pederson on August 09, 2018, 07:53:20 PM

As my Carl Goldberg Cosmic Wind rolled to a stop on a grass landing it flipped over and bent the ST .46 NVA a little (about 5 degrees). At home I bent it back as best I could.

Is it a waste of time and an act of futility to try to straighten a slightly bent NVA? If it is futile, I may switch to full body models to keep from going broke buying NVAs.

I've thought of putting a piece of 1/8" plexiglass under the engine mounting bolts (control line handle side) to stick up higher than the needle valve and hopefully protect the needle valve in next inevitable crash or flip-over. Is the plexiglass a good idea?

Thanks,

Joe Ed Pederson

If you are careful not to damage the threads, you can bend a ST NV about 1/4" above the cap with it screwed in all the way. Not as much fun to set but it takes it out of harms way. Or, get a McCoy NVA with the funny spring...or not.

As to straightening it - go for it but don't damage the threads in the NVA. As long as the inside part is OK and it doesn't leak air, it doesn't much matter what it looks like outside. Plexiglass works. I have used a wire loop too.

Ken

Dan McEntee · « **Reply #2 on:** August 09, 2018, 09:42:12 PM »

As Ken mentions, shorten your needles right off the bat as short as practical. Solder some sort of knob, an old 4-40 nut or something to give you something to grab. The protective 'fin" is an old trick also. Use anything that is thin enough, even 1/16" ply, or thin sheet metal. Make sure the leading corner is well rounded, and the fin is just tall enough to do the job. I even shorten OS and Enya needles. Any needle that is too long can shake like the dickens and the point then becomes like a tuning fork, so keeping them as short as possible no matter what the configuration helps with getting a good engine run.
Type at you later,
Dan McEntee

Mark Mc · « **Reply #3 on:** August 10, 2018, 08:38:38 PM »

This is what I do. 1/16" aluminum just high enough to cover the needle, and it doubles as an engine pad to keep the lug from digging into the doubler.

Mark

Joe Ed Pederson · « **Reply #4 on:** August 11, 2018, 12:29:00 PM »

???This will be my fourth attempt to post a reply. I tried with 3 attached photos taken by my Ipad and I got "error file too large". I tried it with 2 photos; same thing. I just tried with one photo; same thing. Stupid me, I didn't copy my text the first two attempts , so I have typed this response three times. So, here's my response without any photos.

Thanks Ken, Dan, Ty, and Mark for responding.

Ken: I bent the NVA back as best I could and it has worked on two test runs at home. My modeling budget is shot for August, but I'll probably replace the NVA next month.
Dan: After the incident I did shorten the needle valve and bent it over to the same angle they come with. Hopefully, I'll find the time to solder a nut or something on it.
Ty: You suggested just leaving the needle valve alone. I guess I should break some old habits. Since I was a kid I've been returning the needle valve back to the starting position per Cox instructions.
Mark: I put a 3/32" plexiglass fin on the inside of the fuselage to get more clearance for my fingers when turning the needle valve. I made my fin a good 1/2" taller than the ST needle valve to protect the needle valve if she hit on the nose and a wingtip.

The last single photo I attempted to attach would have shown that the leadout lines were made by simply looping the leadout wire over, wrapping with copper wire and soldering. Would this arrangement be allowed at a club field or at a contest?

Thanks for all the help,
Joe Ed

Brett Buck · « **Reply #5 on:** August 11, 2018, 01:17:43 PM »

There is no specification for the leadout connections, so you can do whatever you think will hold together. It is very remotely possible that a CD might not permit it due to "in his opinion" safety authority but that seems unlikely. It *is* a bad idea, but people get away with bad ideas all the time.

On the topic of ST needles, what usually happens when you try to straighen it is that it will get almost straight every easily, and when you try to move it that last little bit, it breaks off. That's because the original crash cracked it most of the way through and then when you are bending it back, the crack closes up, the breaks off the last little hanging bit.

The Harry Higley versions are different, and a softer but tougher, and you can usually bend those back OK.

Until you get a replacement in hand, don't try to get it that last little bit. Also, expect it to break off at some point from vibration, or while you are adjusting it.

Brett

Ken Culbertson · « **Reply #6 on:** August 11, 2018, 01:20:52 PM »

Quote from: Joe Ed Pederson on August 11, 2018, 12:29:00 PM

???This will be my fourth attempt to post a reply. I tried with 3 attached photos taken by my Ipad and I got "error file too large". I tried it with 2 photos; same thing. I just tried with one photo; same thing. Stupid me, I didn't copy my text the first two attempts , so I have typed this response three times. So, here's my response without any photos.

Thanks Ken, Dan, Ty, and Mark for responding.

Ken: I bent the NVA back as best I could and it has worked on two test runs at home. My modeling budget is shot for August, but I'll probably replace the NVA next month.
Dan: After the incident I did shorten the needle valve and bent it over to the same angle they come with. Hopefully, I'll find the time to solder a nut or something on it.
Ty: You suggested just leaving the needle valve alone. I guess I should break some old habits. Since I was a kid I've been returning the needle valve back to the starting position per Cox instructions.
Mark: I put a 3/32" plexiglass fin on the inside of the fuselage to get more clearance for my fingers when turning the needle valve. I made my fin a good 1/2" taller than the ST needle valve to protect the needle valve if she hit on the nose and a wingtip.

The last single photo I attempted to attach would have shown that the leadout lines were made by simply looping the leadout wire over, wrapping with copper wire and soldering. Would this arrangement be allowed at a club field or at a contest?

Thanks for all the help,
Joe Ed

All good but the solder part. You don't want to solder any part of the leadouts from the bellcrank to the handle. Use the AMA approved double wrap and put a piece of heat shrink over it to keep the copper from unwrapping. (Put it on the wire first so you can use a smaller size). You don't want to create a hard spot and the double wrap will let the wires tighten around the eyelet as you pull on them. If you worry about the copper loosening you can put a thin coat of epoxy or JB Weld on the outside but it would be a good idea to pull test it first to tighten the connections.

What Brett said is important. I didn't ask if it was bent in the threaded part. If it is be careful, it will break at some point and you don't want that to be where you can't get it out!

Ken

Joe Ed Pederson · « **Reply #7 on:** August 11, 2018, 02:11:29 PM »

Thanks to Brett and Ken,

When I build a replacement for the Cosmic Wind I will use the AMA guidelines in Figure 3 on page 8 (eyelet and copper wire wrapped control lines) of the AMA CL General guidelines. Ken, thanks for the suggestion of heat shrink tubing.

Brett: I'm following your advice and working on flying inverted at five feet until it's second nature. I'll probably keep flying the Cosmic Wind in that pursuit until I: a) I demolish her or b) I am ready to move on.

When I buy more control lines I'll probably buy finished lines from Tom Morris. I have grave doubts that I could add four eyelets to two bare wires and get both lines to come out even close to the same length. On the other hand, I do have a set of unfinished Sig seven strand .015 wires and I might as well try and see if I can get them to come out equal length.

Brett: While I've got you on the line, let me say you've convinced me to give up on my OS Max S .35 and switch to an OS .25 LA. But hopefully, my Ebay Max S .35 will last long enough to burn the 3 1/2 gallons of Sig Champion 25% castor that I got this Spring.

Thanks guys,
Joe Ed

Brett Buck · « **Reply #8 on:** August 11, 2018, 05:32:35 PM »

Quote from: Joe Ed Pederson on August 11, 2018, 02:11:29 PM

Brett: While I've got you on the line, let me say you've convinced me to give up on my OS Max S .35 and switch to an OS .25 LA. But hopefully, my Ebay Max S .35 will last long enough to burn the 3 1/2 gallons of Sig Champion 25% castor that I got this Spring.

That's great, but don't let perfection stand in the way of good enough. As long as your current setup starts and runs reliably, it's good enough to learn all the basic stunts. Once you get to the more complex parts, then, you probably are going to want a better airplane with the better-performing engine. Start on that now, keep flying the current one, and, if you are pushing yourself enough, the situation will "take care of itself" soon enough.

Sounds like you are doing the right stuff, always remember, learning to build, set up engines, trim, and fly, is a *process*. You are never going to "finish" learning, no one ever has. The process itself is the end goal.

Brett

Joe Ed Pederson · « **Reply #9 on:** August 11, 2018, 07:57:32 PM »

Sounds like you are doing the right stuff, always remember, learning to build, set up engines, trim, and fly, is a *process*. You are never going to "finish" learning, no one ever has. The process itself is the end goal.

Brett
[/quote]

I've always been attracted to hobbies that you are never going to "finish" learning and in which the process is the end goal. And boy, is there a lot to learn. If it weren't for Stunthanger,I would have never realized just how complicated it all is, nor had such a fabulous resource by which to learn about it all.

Later this fall I plan on building a back-up plane to take to the field. The top three candidates (at the moment) are 1) The Brodak Shark 402, 2) the Sig Skyray 35, and 3) Ted Fancher's Medic, little brother to Ted's Doctor from Stunt News May/June 1998. There's even a picture of a younger Brett Buck in the article on the Doctor (p. 61). I'll either cover the model with polyspan or silkspan. I despise Monokote and its offshoots because of the impossibility (as far as I can tell) of keeping fuel/oil from getting under it and soaking into the wood.

In fact, after rereading the article on the Doctor/Medic I may just put the Medic forward to my first choice.

Thanks again,
Joe Ed

Ken Culbertson · « **Reply #10 on:** August 11, 2018, 08:12:48 PM »

Quote from: Joe Ed Pederson on August 11, 2018, 02:11:29 PM

Thanks to Brett and Ken,

When I build a replacement for the Cosmic Wind I will use the AMA guidelines in Figure 3 on page 8 (eyelet and copper wire wrapped control lines) of the AMA CL General guidelines. Ken, thanks for the suggestion of heat shrink tubing.

Brett: I'm following your advice and working on flying inverted at five feet until it's second nature. I'll probably keep flying the Cosmic Wind in that pursuit until I: a) I demolish her or b) I am ready to move on.

When I buy more control lines I'll probably buy finished lines from Tom Morris. I have grave doubts that I could add four eyelets to two bare wires and get both lines to come out even close to the same length. On the other hand, I do have a set of unfinished Sig seven strand .015 wires and I might as well try and see if I can get them to come out equal length.

Brett: While I've got you on the line, let me say you've convinced me to give up on my OS Max S .35 and switch to an OS .25 LA. But hopefully, my Ebay Max S .35 will last long enough to burn the 3 1/2 gallons of Sig Champion 25% castor that I got this Spring.

Thanks guys,
Joe Ed

Joe, I am with Brett on the engine. Unless it is giving you trouble, the 35s is one of the best Stunt engines of it's era. I have over 1000 flights on mine and I still fly it every weekend in my classic. They are a bit prone to overheating so if you get an overly lean run let it cool down a bit between flights. The OS LA series of engines are better but not so much better that I would switch now. It is a huge leap from the Cosmic Wind on a .35 to the current generation of PA ships on a .60+. There are a lot of really good interim planes and I would wait till one of them catches your fancy when you have reached the limits of the Cosmic Wind and get the best engine that plane supports. Please take it one step at a time. I have seen too many people quit when they sped a fortune in time and $$ on a pattern ship too early and crashed it the first day. Now go burn up that Sig Fuel.

PS. I just read your last post as I was typing this. You might want to add the "Fancherized" Twister to your list. With an OS46LA it is a fantastic stunt trainer. Your current list is fine though. Any one of them will get you through learning the pattern. Don't be afraid of MonoKote. If you learn how to seal the edges it is fine.

Ken

Tim Wescott · « **Reply #11 on:** August 12, 2018, 05:31:51 PM »

Quote from: Joe Ed Pederson on August 11, 2018, 02:11:29 PM

When I buy more control lines I'll probably buy finished lines from Tom Morris. I have grave doubts that I could add four eyelets to two bare wires and get both lines to come out even close to the same length. On the other hand, I do have a set of unfinished Sig seven strand .015 wires and I might as well try and see if I can get them to come out equal length.

Drive a finishing nail into a post or the corner of your house or a heavy-enough board (on a bit of plywood or 2x6, and then put a rock or a cinder block onto it). Make up nice line ends on the two free ends, at the comfort of your modeling bench. Then go out to the yard (or the street if you have a really small lot) and put down your anchor. Hang the lines on that and unroll. Measure (remember if you're doing it for a specific length that "official" lengths are center of handle to center of cockpit -- not eyelet to eyelet). Mark one cable so you won't lose it and put it down. Make the other line end out there in the grass or dirt or whatever. You can get the other one pretty even by putting "your" end of the made-up line on a nail and making up the other line with the eyelet on the same nail. There's basically a point where you have 5-10 wraps of copper wire on the first layer where you can adjust things, but they'll stay put when there's no tension on the line. When you get to that point, even things up, let the line go slack, and finish.

If you're making up one set of lines per plane anyway, you can be off in the lengths -- just keep track of which is the "up" line and which is the "down" line.

I can't find if I have pictures, but I have a jig that lets me make lines in the comfort of my shop, without having to grovel in the gravel. Since most of my work time is at night, it's very nice.

Tim Wescott · « **Reply #12 on:** August 12, 2018, 05:36:13 PM »

Quote from: Brett Buck on August 11, 2018, 01:17:43 PM

There is no specification for the leadout connections, so you can do whatever you think will hold together. It is very remotely possible that a CD might not permit it due to "in his opinion" safety authority but that seems unlikely. It *is* a bad idea, but people get away with bad ideas all the time.

The more I use it, the more confident I get of the swage you get from the swaging tool sold by MBS. This crimps the sleeve along it's length, rather than crossways per the rulebook. I have some pretty well-used (and abused) lines with these crimps on them that are still going strong.

That having been said -- doing it the rulebook way is cheaper, and a 1/4-pound roll of #38 copper magnet wire will last forever.

Joe Ed Pederson · « **Reply #13 on:** August 13, 2018, 11:35:01 AM »

Quote from: Ken Culbertson on August 11, 2018, 08:12:48 PM

Joe, I am with Brett on the engine. Unless it is giving you trouble, the 35s is one of the best Stunt engines of it's era. I have over 1000 flights on mine and I still fly it every weekend in my classic. They are a bit prone to overheating so if you get an overly lean run let it cool down a bit between flights.

Ken

Ken,

I had read on the Forum that the con rod in the OS Max S .35 is only good for about 300-350 flights. So, 1) Is your Max S a reworked one or is it stock? 2) Since you've got 1000 flights on it, I have to ask what ratios of castor to synthetic you use and if you use any additives. 3) What muffler are you using and have you found that one type of muffler (tongue vs stock OS) makes the overheating worse or does the type of muffler make no difference in how hot the engine runs? I nosed over in the grass on take-off recently and the engine would not restart until it cooled down. She starts readily when she's back to room temperature. I haven't had any lean runs on my Ebay Max S and Jim Lee looked at her and said the venturi inner diameter is good.

I will take it (learning to fly) one step at a time. I couldn't afford a top notch PA engine and a top notch world competition model even if I wanted one. The very generous John (Doc) Holliday gave me a well-used Fancher Twister. I've bought aluminum plates (1/8 x 3/8 x 2) from Tom Morris to mount my engine to so I won't have to drill any more holes in the Twister's nose, but I'm in no hurry to start flying it.

I expected to have a lot more flights on the Cosmic Wind by now. I've been very frustrated with the weather and my schedule this year. But I'm sure that most flyers don't get to fly as often as they would like. I'm not waiting for dead calm. I'm just waiting for less than 12 mph and a 2 hour space of open time.

Thanks,
Joe Ed

Joe Ed Pederson · « **Reply #14 on:** August 13, 2018, 11:36:33 AM »

Tim,

Thanks for the help on how to make the lines equal length.

I appreciate it.
Joe Ed

Ken Culbertson · « **Reply #15 on:** August 13, 2018, 01:05:55 PM »

Quote from: Joe Ed Pederson on August 13, 2018, 11:35:01 AM

Ken,

I had read on the Forum that the con rod in the OS Max S .35 is only good for about 300-350 flights. So, 1) Is your Max S a reworked one or is it stock? 2) Since you've got 1000 flights on it, I have to ask what ratios of castor to synthetic you use and if you use any additives. 3) What muffler are you using and have you found that one type of muffler (tongue vs stock OS) makes the overheating worse or does the type of muffler make no difference in how hot the engine runs? I nosed over in the grass on take-off recently and the engine would not restart until it cooled down. She starts readily when she's back to room temperature. I haven't had any lean runs on my Ebay Max S and Jim Lee looked at her and said the venturi inner diameter is good.

I will take it (learning to fly) one step at a time. I couldn't afford a top notch PA engine and a top notch world competition model even if I wanted one. The very generous John (Doc) Holliday gave me a well-used Fancher Twister. I've bought aluminum plates (1/8 x 3/8 x 2) from Tom Morris to mount my engine to so I won't have to drill any more holes in the Twister's nose, but I'm in no hurry to start flying it.

I expected to have a lot more flights on the Cosmic Wind by now. I've been very frustrated with the weather and my schedule this year. But I'm sure that most flyers don't get to fly as often as they would like. I'm not waiting for dead calm. I'm just waiting for less than 12 mph and a 2 hour space of open time.

Thanks,
Joe Ed

Joe - My OS was reworked early in it's life and I do not know what was done to the crankshaft and connecting rod. All I can say is that it still has very little "slop", even when cold. It did have a Teflon insert in the crankshaft to keep it from hitting the back-plate. That may extend the life and a higher quality connecting rod may have been put in.

I use "Wildcat 10% Premium fuel which is a caster/synthetic 16% total. Engine really likes it. Ran VP "GMA 5/22" and it hated it. Runs OK on VP "AIR 10" which is a very similar mix to the Wildcat. As long as I dosn't scream at the end for too long it restarts normal in about 10 min. I am using one of the really old Jet Stream mufflers. Really just a "Cheater" from the 70's.

You are in good hands with the Twister.

Dead Calm is a death wish in Stunt. You really want a steady 5-7 blowing about 45degrees from directly out of the Sun. 3-5 if you are new at it. Once you start flying at 5', wake turbulence and the dead air that comes with no wind can pancake even the best of us in a corner faster than you can say "Oh S...".

Ken

Tim Wescott · « **Reply #16 on:** August 13, 2018, 02:18:53 PM »

Quote from: Ken Culbertson on August 13, 2018, 01:05:55 PM

Dead Calm is a death wish in Stunt. You really want a steady 5-7 blowing about 45degrees from directly out of the Sun. 3-5 if you are new at it. Once you start flying at 5', wake turbulence and the dead air that comes with no wind can pancake even the best of us in a corner faster than you can say "Oh S...".

Several years ago I was graced with about four or five months of dead calm mornings, two days a week. It was at exactly the right point in my growth as a stunt pilot to learn to do good-looking maneuvers while walking backwards.

But I wouldn't recommend it for an absolute beginner.

Brett Buck · « **Reply #17 on:** August 13, 2018, 02:41:05 PM »

Quote from: Joe Ed Pederson on August 13, 2018, 11:35:01 AM

I had read on the Forum that the con rod in the OS Max S .35 is only good for about 300-350 flights.

I snipped the rest, which are good questions. but, ultimately, I don't think it matters too much. 350 flights seems a little pessimistic, but, run it until it won't any more, or you replace it with something else. 350 flights is a lot, you should certainly have moved on (because you have reached the limits of performance) or crashed the airplane beyond practical repair by then. That's not a negative - I have built probably 50 stunt planes of various stripes, and I have 4 of them left right now.

Brett

Ken Culbertson · « **Reply #18 on:** August 13, 2018, 02:58:52 PM »

Quote from: Tim Wescott on August 13, 2018, 02:18:53 PM

Several years ago I was graced with about four or five months of dead calm mornings, two days a week. It was at exactly the right point in my growth as a stunt pilot to learn to do good-looking maneuvers while walking backwards.

But I wouldn't recommend it for an absolute beginner.

That happens so infrequently in Texas that we forget. Whomp.... And that is why my planes have double the control movement necessary for the pattern!

Ken

Peter in Fairfax, VA · « **Reply #19 on:** May 05, 2019, 09:22:43 AM »

Great topic. Started with bent NVA, but then veered off into how to tie lines and even OS 35 conrods.

Back to the NVA, yes, shorten it. However, to bend it, heat it red hot with a torch. Otherwise, it may break. If you are not comfortable with a torch, saw off the needle and bolt on a wheel collar.

FLOYD CARTER · « **Reply #20 on:** May 05, 2019, 10:26:43 AM »

Back when I flew some profiles (no more) I was concerned about the NVA sticking out on top. I bent a piece of 1/15 piano wire in a half-loop and fastened that to protect the NV. It doesn't show as much as a plywood piece.