Aileron nose ribs

G

geraldmorrissey

Well-known member
Has the profile of the above changed over the years? I'm sure I read that a change was made however I can find nothing in the engineering change notices, nothing mentioned in the Patrol plans built list, all seven pages, nothing. A general search of all lists showed nothing. Am assembling my ailerons and need to know I'm not going crazy. My ribs are factory but at least 10 years old.
Thx
Gerry
Patrol #30
 

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The shape of the aileron nose rib did change at one point. The bottom is more flat as seen in the pics of newer plans. Instead of curving up towards the leading edge. I suggest you get with Bob and request a drawing of the newer style aileron nose rib. Mark
 
I talked to Mike at Bearhawk, indeed the aileron nose ribs have changed. No engineering change notice that I can find. Such a significant change to a control surface warrants a change notice. Maybe they did, can somebody point me to it. I went through the change order list again this morning, no joy. Obviously I need a new set of drwgs. Mike also said that the old configuration could be cut, new web and flange added on to get close to the new configuration.

Gerry
Patrol #30
 
One needs to be clear if the change is a mandatory "change notice" that addresses a safety concern, or if it's an optional change for product improvement that may or may not be published. If the latter I'm leaving my ailerons as-is.
 
Gerald;

My 2017 Patrol kit came from the factory with the same nose rib yours has. I bet Bob's Patrol has our nose rib shape. I'm not concerned. I wonder if maybe the change was made to streamline production of ailerons in a factory setting amongst all the different models as opposed to an issue. But I don't know. Just a theory. It seems like I talked with Mark about it years ago and it was not an operational issue that changed the design.
 
Interesting. I am in the same boat in that I have acquired aileron nose ribs that are the older style. They do not match my updated blueprints. I'll have to decide if I am making new nose ribs or going with the older ones. I plan to see Bob Barrows this week, perhaps I will ask him about the design change.
 

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Bob will tell you that there were 3 versions.

The original profile was flatter much like the present version with the flatter profile.

At some point a builder wanted to make his patrol make faster turns. So Bob came up with the curved design more appropriate for high speed turning.

Probably, most patrol fans wanted light stick force instead of the ability to make fast turns. Hence it is back to the flatter profile.

It is just a question of what you want optimized. The present default is light control force on the stick. Neither one is right or wrong. Just what do you want optimized.
Both are 0.025

Neither here nor there but:
The more recent version uses a 7/8 tube . The curved version used a 3/4 tube. As far as I know both tubes could hold the right amount of lead.
 
Data point:

For West 105/206 epoxy and #8 washed, uncoated shot with 1/2" cork cap at one end, the 7/8" center tube in the Patrol comes out at almost exactly 6 pounds. A molten pour would hold 1/3 more lead, but take away the epoxy mass, so roughly 8.7 lbs (which would require some lead removal or capping the tube a bit further in versus epoxy slurry pour). A 3/4" tube will hold about 30% less by volume, so makes a molten pour attractive to get all but trim weight in that center tube.
 
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I need to perform the lead weight step. I have always thought my table router with spiral bit grabbing was the most dangerous operation. Probably molten lead is next.

In the case of the Patrol - with a 7/8 tube -

Do you think 4 lbs lead per wing is enough or do you think I need to more?

Also, what should I use to provide a cork for a molten pour?

I am surprised by the cost of lead.



sjt
 
Thats where i got my lead. To form my lead slugs, I fabricated a mold by clicing a piece of steel tubing (with the right ID) on the vertical axis. Then I put the two halves back together with safety wire and sealed the joint with drywall compound...that stuff is ground rock and will not melt or burn. Pouring went pretty good and I got solid lead slugs with out too much mess. Heat your lead in a pan that you can disose of on your coleman stove outside. Lead Fumes are not good for you.

BTW, I have the 3/4 tubing and I feel I needed solid slugs to get the weight right. I doubt the density of lead shot would have been ok...I may have even filled it and figure out I did not have enough. Long time ago.
 
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Melting lead for sure can be dangerous. Never had a problem the several times I have done it. Recently, I have just filled the long tube with fine lead shot. Sealed both ends well obviously. That has been enough. If more is needed you could always use another piece of aluminum tube for additional counter weight in the further inboard section of the aileron nose ribs. Mark
 
Let me suggest that it would be great to have folks that have finished their wings to airworthiness to weigh in on this... experience beats 'I think...' just about every time.

For a molten pour, I think I would weld a 1/16" aluminum cap on one end of the tube or press-fit an 1/8" shop-made aluminum disk of correct diameter with edges upset with a center punch, then bury that end of the tube in dry sand. For epoxy and lead slurry, a cork pounded into one end works fine... leave the tube a little over-length, then trim back to get a very nice looking surface off the tablesaw.

I ran back through the forum as well as available newsletters, and it looks like the range on aileron balance weight is from just over 5 lbs to just under 6 lbs. For an Oratex covering job, about 5.1 lbs of lead was reported as perfect, while more traditional systems with nice paint seem to require from 5.5 lbs to about 5.9 lbs. Carlo suggested that final tuning of the weight could be addressed after getting the ailerons covered, as the math gets a little easier once the only additional weight added is paint, so we went with a target weight of 5 lb 14 ounces for all four tubes and prepped them for future weight removal (dimpled the ends to line up the bit for drilling out the outboard end).

Like Mark mentioned, when I have done poured lead (mostly for marine work), it's been pretty easy if the mold is well supported and sealed. Saw a sailboat keel pour that made a terrible mess as the bottom of the mold blew out from the hundreds of lbs of lead above. The amateur builder thought keeping things above ground would make handling the casting easier and avoid digging it out. Had some fun collecting up all that lead spill from his yard. The next time they poured that keel, his crew dug the recommended hole, set the mold in place, and back-filled with tamped sand. Good support and good sealing makes for a safe pour.
 
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I used about 1" of modeling clay at the bottom of the tube to seal it for the lead pour, worked perfect. I did add some extra length to the tube before filling. The tube ended up just a little heavy, drilled out a small amount of lead to get a very slight nose heavy balance.
 
I've previously melted lead for a variety of uses, but in this case I used lead shot and epoxy. It helped to warm the epoxy and then it flows better. One small thing to watch for, the tubes need to be held in place in the aileron nose ribs, I used rivets. The rivets need to be checked regularly. The position of them - at least on my build - is such that if a rivet migrated out it could bind the aileron. If the tube were to move laterally this also wouldn't be good. Also, if a rivet loosened, then the lead shot could potentially escape. I did make every effort to mix the epoxy all the way through but no easy way to tell if this was successful. My first attempt at pre-mixing the shot with epoxy, then pouring into the tube, didn't work, it simply wouldn't pour. That said, I've just completed an Annual at 300 hours, and no issues at all.
 
Thanks for the reply, that is just what Bob said. He suggested I go with the flatter ones. While he has the curved ones on his patrol now, he said he would have put the flat style back on his but he said he would have had to mess with the hinge alignment to go back to the original setup for his and he didn't want to bother with that amount of work.
 
As SJT commented below, Bob said the original design was flat. He said you could feel turbulence on the controls when doing full deflection turns above 100mph. The curved design fixed that and allowed full control inputs at high speeds. It however made the controls feel heavier - less responsive. So the design was changed back keep the lighter feeling on the controls.
 
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