Steve Pierce
BENEFACTOR
Graham, TX
Yes, only the two on the vertical fin because of the steeper angles. I have seen these cracked at the radius a few times when the waashers were not installed.
Tail brace wires
- Thread starter swoeric
- Start date
Yes, only the two on the vertical fin because of the steeper angles. I have seen these cracked at the radius a few times when the waashers were not installed.
Binty
Registered User
South Island, New Zealand
Id 2nd this advice... As I recorded in an earlier post (search "Nipples and Safety") ours were in bad shape too. There are not many 'Jesus Nuts' on the Cub but I reckon these are one such example. To check these properly, they require dis-assembly. I have a feeling the dis-assembly part is often overlooked on inspections- It certainly was on ours.
Binty
Registered User
South Island, New Zealand
Fascinating film! I never thought it would make a magnitude 9 difference?!! I think iv just discovered why my Climb performance has been KILLED after installing 29" ABWs
courierguy
MEMBER
Inkom, Idaho
About 18 years ago I found some PVC airfoil shaped snap together fairings that were being pushed to the hang glider and ultralight boys for drag reduction. As it was designed for 3/32 cable, and that's what my Rans S-7 at the time used for tail bracing, it seemed like a natural to try it. After carefully fitting it, doing a real good job and liking how it could swivel a bit to find its best AOA, I test flew it. As I got above 50 mph, severe flutter started in, I could feel it in the stick. I looked back there and the cables were a blur. They came off for good a minute later, too bad as for sure reducing drag anytime I can is a good thing. Round stainless is what they use now back there, maybe I'll try the hobby shop route and give it another shot.
mike mcs repair
Registered User
chugiak AK
too neutral of a AOA position?, hunting????
courierguy
MEMBER
Inkom, Idaho
Yes, something like that I guess. It just freaked me out so off they came. SD Cubman has me getting fired up about the idea again though! Just because there is no airspeed noticeable difference doesn't mean it isn't worth it. I like the "stick it out the car window or bed of the pickup while going 80 mph" concept of drag or lack of affirmation. I first did that 30+ years ago (40 mph) with a round piece of tube that we used for the kingpost on hang gliders and it damn near ripped my arm out of the socket. After slipping a soft foam airfoil fairing over it someone was making back then, the difference was dramatic. More recenty I did the same thing when I converted the RANS to Cub style gear, trying to decide whether to fair and cover it (note, not just cover, but also fair the TE) and again, the difference was dramatic.
I am a few days away from taking the 29" Airstreaks off and putting the 8:00's on (the biggest that work with my Datum retract skis) and usually I make a flight just to see if there is any difference in speed with the small tires. None at all, yeah right, I wish!
I am a few days away from taking the 29" Airstreaks off and putting the 8:00's on (the biggest that work with my Datum retract skis) and usually I make a flight just to see if there is any difference in speed with the small tires. None at all, yeah right, I wish!
skywagon8a
MEMBER
SE Mass MA6
courierguy, What mike says above coupled with the tension of the cables could have been the trouble. Try again with the cables tightened a bit more and use some RTV at the upper end to increase the resistance of the fairings to flutter.
courierguy
MEMBER
Inkom, Idaho
Yeah, I was just thinking the same thing.....I will pursue it again. This time with the K & S stuff. Thanks Larry.
Just did a search for K & S, I guess I don't understand how they size it. They don't specify what the I.D. is, they do call out various sizes but it's not clear if that's the overall size, I.D., or whatever. It's cheap enough, that's good. I'll run down to an local hoby shop and get educated.
BTW, I got a bit over 2 hrs. dead stick ridge soaring this year, several 10 or 15 minute flights, one an hour, so I appreciate any drag reduction probably more then most.
Just did a search for K & S, I guess I don't understand how they size it. They don't specify what the I.D. is, they do call out various sizes but it's not clear if that's the overall size, I.D., or whatever. It's cheap enough, that's good. I'll run down to an local hoby shop and get educated.
BTW, I got a bit over 2 hrs. dead stick ridge soaring this year, several 10 or 15 minute flights, one an hour, so I appreciate any drag reduction probably more then most.
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cubdriver2
FRIEND
upstate NY
I still have original streamlined wires on my J4 tail, just like the flying wires on a biplane they need to be a few degrees off center to keep them loaded so they don't flutter
Glenn
Glenn
Steve Pierce
BENEFACTOR
Graham, TX
Sorry Gary, I quoted you the wrong part number. U81102-002 is the square washer under the brass barrel that tightens the wire.. What you need is 40131-000. Sorry about that, it is item 10 on figure 23 in the parts manual. Send me an address and I will send you a pair.
Kodiakmack
Registered User
winters in Utah, Summers in Idaho
Hey all,
I'm looking to go to the round wires. As a -12 with the -18 flap/tail conversion I'm looking for guidance in finding the correct part numbers, and would really love to find a kit with everything in stainless. Help appreciated as always!
I'm looking to go to the round wires. As a -12 with the -18 flap/tail conversion I'm looking for guidance in finding the correct part numbers, and would really love to find a kit with everything in stainless. Help appreciated as always!
Steve Pierce
BENEFACTOR
Graham, TX
Call Dakota Cub [FONT="](605) 757-6628[/FONT] DC41031-KIT . Found a broken clevis on a friends Clipper at Oshkosh and the DC guys and gal loaned us the tools and gave us a new clevis to get him home safely.
Kodiakmack
Registered User
winters in Utah, Summers in Idaho
Thank you Steve.
courierguy
MEMBER
Inkom, Idaho
Nothing like reading a post and getting all fired up to make a comment....only to see you already did, 6 years previous!
I never did follow up on trying to streamline mine on the S-7 again, after my bad experience with the PVC stuff (not that the type of material was the cause of the flutter), but most likely the fact that I left it to "freewheel", thinking it would auto find it's best location. This thread has inspired me to try it again, and this time I'll shoot a little goop of some sort on the ends (probably Lexal, my go to goop these days, an adhesive caulk of sorts that stays crystal clear, and is specifically made (among other uses) for adhering different types of plastics to each other. Though I will try the aluminum streamline stuff this time.
Found this:
The big advantage of this plastic stuff is how it can simply slip over the rods, then be secured. https://antisplataero.com/
I never did follow up on trying to streamline mine on the S-7 again, after my bad experience with the PVC stuff (not that the type of material was the cause of the flutter), but most likely the fact that I left it to "freewheel", thinking it would auto find it's best location. This thread has inspired me to try it again, and this time I'll shoot a little goop of some sort on the ends (probably Lexal, my go to goop these days, an adhesive caulk of sorts that stays crystal clear, and is specifically made (among other uses) for adhering different types of plastics to each other. Though I will try the aluminum streamline stuff this time.
Found this:
The big advantage of this plastic stuff is how it can simply slip over the rods, then be secured. https://antisplataero.com/
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Things tend to flutter when the CG is behind the hinge point.
To prevent flutter on my ailerons and my elevator I balance them with lead. When I read your post #37, I wondered if flutter might not be an issue. It seems to me like if you somehow added weight to the leading edge of the streamline tubing then it would have natural flutter resistance. Maybe a piece of 1/8" diameter solder put in the leading edge of the streamline tubing?
courierguy
MEMBER
Inkom, Idaho
Since these fairings are apparently used by the go fast RV crowd, amongst others, it would seem that fixing them into place is adequate. I would hoist the tail up to a flying attitude, and then just eyeball them into place while the goop sets. I'd take the test flight seriously. I have about 18' of round rod that could be faired, and while I was at it I'd fair my com antenna with the scraps. I emailed him to see what lengths it comes in, I am willing to give it a shot, screw the money, it's for the plane! I need to tell him about my previous experience, and get his take on why it happened.
courierguy
MEMBER
Inkom, Idaho
No response to my email, several days later, from antisplateaero. I may call but that seems so 20 th. century. I never added up my total hor stab bracing lengths before, 18' of round rod, about the only round stuff left exposed to the airflow, besides the Airstreaks.
skywagon8a
MEMBER
SE Mass MA6
Try gluing balsa wood to your round wires. Here are some trailing edge sections. $3.84 will get you 18' of faired balsa.
https://www.nationalbalsa.com/trailing_edge_p/181236te.htm
courierguy
MEMBER
Inkom, Idaho
Now you tell me! Just ordered.
That's ok, my plane is so trouble free and gives me so much enjoyment, throwing money at it now and then doesn't bother me. Like buying flowers for an already happy wife.
That's ok, my plane is so trouble free and gives me so much enjoyment, throwing money at it now and then doesn't bother me. Like buying flowers for an already happy wife.
courierguy
MEMBER
Inkom, Idaho
Got them installed, and I think I may have gained 5 mph in cruise. Then again, I haven't flow it yet, so it could just be wishful thinking! They pass the "I can't see it while flying so don't care" visual test anyway. Blue tape holds while the Lexal sets up. I paid for 6 3' lengths, he has the stuff in 5' lengths only, but sent the scraps along gratis, so I did my com antenna also. So about 19' of round rod, now faired. I'm driving into town today and will be on the interstate, and will do the aero test of setting the cruise control at 80 mph, and then holding a similar size rod out in the breeze, then will slip the fairing on it and see if I get pulled over for inattentive driving.
Attachments
skywagon8a
MEMBER
SE Mass MA6
You missed the lower rear wire. 
courierguy
MEMBER
Inkom, Idaho
My lower rear struts were not missed, but as I did a mod back there I won't go into, the original struts didn't have enough adjustment to work. So I went back to what the earlier S-7's used, and as an old hang glider and ultralight pilot, am pretty comfortable with, good old 7x7 3/32 cable. It's never let me down. Ha ha. Didn't think the fairing were applicable for it's smaller size, point being.
Got 10 hours or so on it now since installed. Figured a top speed run would be best to show any difference, so made a note of the unfaired top speed, and the ambient conditions first. Then, after the install, was able to replicate the same conditions, EXCEPT for the OAT being 6 degrees higher..... and the top speed was EXACTLY the same. So, either they "don't work", or they work a little, but beyond what my ASI could show. The unknown, to me anyway, is what difference my test conditions and indicated speed made with a 6 degree high temp difference? I would be thrilled if I could affirm a solid 1 MPH ind. speed improvement, could the 6 degree higher temp in the after installed test account for enough variance that I can claim that?
Don't know.... but I'm not taking them off, no flutter anyway or other adverse effects, and the weight of them is nothing. I've frittered away more money then the approximately $250.00 they cost (with freight) on flying related gizmos before, without losing any sleep over it, and at least now I can rest easy every round thing on the plane is faired. Meanwhile, when other S-7 pilots remark on them, I'll claim a solid 5 mph speed increase just to mess with them.
Got 10 hours or so on it now since installed. Figured a top speed run would be best to show any difference, so made a note of the unfaired top speed, and the ambient conditions first. Then, after the install, was able to replicate the same conditions, EXCEPT for the OAT being 6 degrees higher..... and the top speed was EXACTLY the same. So, either they "don't work", or they work a little, but beyond what my ASI could show. The unknown, to me anyway, is what difference my test conditions and indicated speed made with a 6 degree high temp difference? I would be thrilled if I could affirm a solid 1 MPH ind. speed improvement, could the 6 degree higher temp in the after installed test account for enough variance that I can claim that?
Don't know.... but I'm not taking them off, no flutter anyway or other adverse effects, and the weight of them is nothing. I've frittered away more money then the approximately $250.00 they cost (with freight) on flying related gizmos before, without losing any sleep over it, and at least now I can rest easy every round thing on the plane is faired. Meanwhile, when other S-7 pilots remark on them, I'll claim a solid 5 mph speed increase just to mess with them.
bob turner
Registered User
Really. I cannot measure the difference wheel pants on or off my Decathlon, and at 120 kts speed fairings are a lot more effective than at a Cub-like 80. We do have streamline tail wires on the J4, and while my partner disagrees, I maintain it is at least 10 mph faster than the J3 (with or without wheel pants). Probably all that is due to the wires, huh?
courierguy
MEMBER
Inkom, Idaho
It HAS TO help a little bit is my thinking, even if it's not apparent on the ASI, it gives me a warm fuzzy feeling, even if it's half a MPH, and a tiny bit more range/duration/glide. I am trying to replicate the same OAT temp for another test, rather than 6 degrees warmer, to see what effect that has, if any, on my top indicated speed, which you'll notice I don't bother to state, I have my pride.
skywagon8a
MEMBER
SE Mass MA6
I suggest it is due to the wider fuselage. Remember, a Blimp is supposed to be the most efficient aerodynamic shape. The J-4 is a faired out J-3.
courierguy
MEMBER
Inkom, Idaho
The RANS S-20, a side by side design, uses the exact same wing as my S-7, you can imagine my chagrin when word filtered back that the chubby 20 is a bit faster than my svelte 7.
