Wing tip reinforcement
Posted: Sun Jun 29, 2014 10:41 am
by jcondon
I’ve installed the full size wing tips using #4 screws and nutplates. The installation came out well however there is a LOT of unsupported fiber glass in the tips and I’m thinking I should probably reinforce it some way. I could spend a lot of time fitting foam and fiberglass supports or just install an extra set of wing ribs half way into the tips. The ribs would probably be easier and lighter than fiberglass reinforcement although I hate to see what the price is for an extra set of ribs ;(.
Anyway, wondering what others have done when using the full size, untrimmed wing tips.
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 11:03 am
by Bryan Cotton
The loads would be low out there , are you sure you need it? If you did why not a foam rib glued in place? Have any blue foam left over from a house project?
Wing tip reinforcement
Posted: Sun Jun 29, 2014 11:52 am
by Sonex1517
Purely my opinion, but have we heard of any issues, failures, incidents or accidents resulting from a wing tip?
If not I am thinking the designers knew their stuff and we should not re engineer it…purely my two cents.
Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 12:07 pm
by fastj22
Rule #1 - Build to the plans.
Rule #2 - If tempted to deviate from the plans, see Rule 1.
Rule #3 - If you are still convinced you have a better design and the hundreds of Sonex are built wrong, revisit Rule 2.
That being said, I did go with some mods that violated the rules. Swing back canopy is one.
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 12:54 pm
by jcondon
Appreciate the feedback but I don’t know if this issue is applicable to non-OneX models. The OneX untrimmed wing tip is 20” long, the original tip design was extended to provide sport pilot compliance for “fluffy” pilots. Are the wing tips on non-OneX models this long and unreinforced?
My RV-9A has similar wing tips but probably only 12” long and they ARE reinforced as most RV tips. I know an RV is not the same as a OneX but they are similar. I think many if not most of the OneX builders trim the tips down so when they are folded they will fit under a standard garage door so there probably aren’t too many data points out there regarding full 20” length tips and any problems encountered. I’m not just concerned about total failure and the tip coming off but also concerned about cracking and vibrations.
Anyway, I appreciate the input.
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 2:26 pm
by fastj22
jcondon wrote:Appreciate the feedback but I don’t know if this issue is applicable to non-OneX models. The OneX untrimmed wing tip is 20” long, the original tip design was extended to provide sport pilot compliance for “fluffy” pilots. Are the wing tips on non-OneX models this long and unreinforced?
My RV-9A has similar wing tips but probably only 12” long and they ARE reinforced as most RV tips. I know an RV is not the same as a OneX but they are similar. I think many if not most of the OneX builders trim the tips down so when they are folded they will fit under a standard garage door so there probably aren’t too many data points out there regarding full 20” length tips and any problems encountered. I’m not just concerned about total failure and the tip coming off but also concerned about cracking and vibrations.
Anyway, I appreciate the input.
Sorry, I missed the part about this being a Onex tip. That clearly was an afterthought by Sonex to get the Onex sport pilot legal with a hefty pilot. The Sonex/Waiex tip is just a flat fiberglass plate that caps the wing tip. My 2 cents (and worth every dime) is the tip is probably fine unsupported without a rib. I would be more concerned with not having the spar extend into it. But, Sonex does a pretty damn good job being conservative on their engineering. Looking at other kits, the Sonex is a tank.
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 4:04 pm
by merle reppert
WING TIPS-----Thw wing is loaded around 11 LBS pe rsquare foot including the wing tips -------
Talk to Kerry --And build it rer plans ----I wouldn’t fly it with 4-40 screws especially if you have the long tips –
Merle Reppert —ONEX 0049 67 Hours
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 5:29 pm
by jcondon
Merle,
I’m surprised you consider a 1/8” pulled aluminum rivet to be stronger than a #4 – 40 steel screw. The 1/8” pulled rivet has a .125” hollow aluminum shaft with a steel mandrel about .076” diameter compared to a 4 – 40 screw that has a steel shaft .112” diameter. Also, if the steel mandrel happens to break near or below the material surface it is bonding or fall out of the rivet body completely as sometimes happens, it has a lot less strength. I’ve followed discussions on other forums comparing the strength of pulled rivets to screws and the consensus has been a 4 – 40 screw is an acceptable replacement for a 1/8” aluminum rivet with steel mandrel. Maybe you have had some bad experiences with 4 – 40 screws or perhaps you have some other information regarding strength comparisons?
Re: Wing tip reinforcement
Posted: Sun Jun 29, 2014 8:59 pm
by merle reppert
Plans call for stainless pulled rivets --NOT Aluminum
Merle
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 1:06 pm
by clevtool
Merle,
Before posting alarmist comments like ‘I wouldn’t fly it’, that will be on the internet forever for all to see, could you back up your response with some data? I have yet to do any calculations, but my first assumption is that a solid steel screw will be higher in shear than a tubular steel rivet. My second is that the heads are similar in size so the tension force on the top should be similar, and with the nutplate on the bottom, the tension stress on the bottom would be far less with the screw. Third assumption is that the tearout strength of the aluminum skin would be the failure mode with either fastener.
We have #4 screw kits on thousands of flying RV’s at higher speeds (but with less loading area) with not one complaint in 20+ years. I know that builders are using the screws in other areas for pull rivet replacement as well. We selected this combination because of their size being similar to the pull rivets, where #6 or #8 screws just don’t look right and seem to draw your eye.
If there is cause for alarm, send me some data as I need to ensure that we are not being unsafe, but this seems like more of a visceral comment like ‘I would never drive a Ford’?
Mike Lauritsen
Cleaveland Aircraft Tool
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 2:19 pm
by SvingenB
jcondon wrote:I’ve installed the full size wing tips using #4 screws and nutplates. The installation came out well however there is a LOT of unsupported fiber glass in the tips and I’m thinking I should probably reinforce it some way. I could spend a lot of time fitting foam and fiberglass supports or just install an extra set of wing ribs half way into the tips. The ribs would probably be easier and lighter than fiberglass reinforcement although I hate to see what the price is for an extra set of ribs ;(.
Anyway, wondering what others have done when using the full size, untrimmed wing tips.
I am wondering about long vs short tips. I asked Sonex about it, and the answer was start with the long and cut them later if you want to. This of course is not a very informative answer. Why do you want long instead of short?
Why would you support it with a rib? I would think any support would have to be extension of the spar.
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 4:11 pm
by onex0127
On my aircraft, I am starting with the long wingtip first. I purchased from Air Ward their wingtip removal kit which use’s #6 screws. The kit was very easy to install and if I find I want a little more speed, I can always shorten the tips. As far as how strong is the long tip and does it need support. I can pick up the left or right side of the aircraft by the wing tip with no problem. Now I do not have the engine in yet, but it seams to be very strong. And the Sonex Onex seams to be doing OK.
Roy Taylor
127
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 4:53 pm
by jcondon
The reason I’m going with the full size tips is because Sonex says they are necessary to maintain Sport Pilot compliance for pilots weighing over 175 lbs. Since I weigh over 200 I figured the full size tips would be a good idea, especially if I get a picky DAR when I have the aircraft inspected. I have a private pilot certificate but the Sport Pilot stuff is new to me and I just didn’t want to create any avoidable problems.
My reason for reinforcing the tip was not to add structural strength but to stabilize the wingtip surfaces. The upper and lower surfaces of the full size tip are quite large, thin and unsupported. My concern was the surfaces may tend to “oil can” or deform in flight and I was considering adding some type of internal support to the tips to help keep their airfoil shape in flight, not to provide additional structural strength. I probably wasn’t clear about that in my post.
I know some RV builders have added foam and fiberglass to the inside of tips to help maintain shape and on my RV9, the kit included some aluminum bulkhead type supports I riveted inside the tips to help maintain shape. I thought adding another OneX wing rib halfway into the tip would be a fairly easy process and keep the airfoil shape in the tip without the top or bottom surfaces collapsing or oil canning. The weight of the extra rib would be minimal, probably less than any foam and fiberglass support I might fabricate. I know the rib would not be attached to the spar but the purpose of the rib is to just maintain the tip airfoil shape, not provide structural support.
Note: Just heard back from SoneX tech support and they do not feel any additional support is required for the full size tips. I’m still waiting to get a recommendation on hardware for making the tips “easily removeable” as stated on their web site. I also appreciate Mike Lauritsen’s (Cleaveland Tool) knowledge and input regarding screw and rivet strength.
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 5:18 pm
by radfordc
jcondon wrote:The reason I’m going with the full size tips is because Sonex says they are necessary to maintain Sport Pilot compliance for pilots weighing over 175 lbs. Since I weigh over 200 I figured the full size tips would be a good idea, especially if I get a picky DAR when I have the aircraft inspected. I have a private pilot certificate but the Sport Pilot stuff is new to me and I just didn’t want to create any avoidable problems.
Whether you want long wing tips or not is your business. The DAR’s job is to determine if the aircraft meets airworthiness standards…not to determine if the pilot flying the plane is legal or not. Since the aircraft is not eligible for a “light sport” registration the length of the wing tips is irrelevant to the inspector. Once the aircraft is deemed airworthy it’s your job to fly it “legally”.
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 5:42 pm
by jcondon
That’s good information to know, I’m just not up to speed yet regarding Sport Pilot or Light Sport regulations.
I just want to be able to legally fly the airplane if I later choose not to renew my medical certificate. So, either long wing tips or losing 25+ pounds are my choices and long wing tips are probably the most realistic choice for me.
Re: Wing tip reinforcement
Posted: Mon Jun 30, 2014 8:24 pm
by fastj22
jcondon wrote:That’s good information to know, I’m just not up to speed yet regarding Sport Pilot or Light Sport regulations.
I just want to be able to legally fly the airplane if I later choose not to renew my medical certificate. So, either long wing tips or losing 25+ pounds are my choices and long wing tips are probably the most realistic choice for me.
I’ve been following the development of the Onex since I sat in the prototype in 2011 at a builders clinic. The tips were not in the equation then. After flight testing at gross, Sonex offered the tips. I guess the stall speed was over light sport limits without them. Your DAR won’t care. The only way you would get into a pickle is if you had an incident at gross with short wings and the FAA got up in your grill about it looking for a reason to violate you. Jeff Schultz told me that after his off airport landing, the FAA claimed his Jab3300 Sonex wasn’t light sport compliant. He’s a private pilot so it really didn’t matter.
If I were building a Onex, I’d definitely look at that Ward kit to quickly switch out the tips.
Re: Wing tip reinforcement
Posted: Tue Jul 01, 2014 9:42 am
by 75sx
How about both??? Dr. Jim.
Re: Wing tip reinforcement
Posted: Mon Sep 08, 2014 8:33 am
by alien
I have/had the same thoughts about these long unsupported wing tips. I wonder if one ever pulls 4, 5 or maybe 6 G’s when a loop or spin doesn’t work out the way we want, or at the Onex’ Never Exceed Speed of over 180 kts, if those riveted tips would survive. So I cut them in half and hope for the best.
As for the comment made to stick to the plans, I wonder what can be wrong with the following:
the upper seatbelt attachment is done with 3 rivets. The bolt in the seatbelt bracket itself is of a huge size. I replaced two of those rivets by AN3 bolts (and so did many others).
The Onex is full of shortcomings left and right, at least the early plans, so changes area good idea in many instances and showed up many times in Revisions as a result of builder comments and modifications made.
Robert, Onex 81