marwen1

My Feedback: (6)

I have some very large WING EXTENSIONS on a DELTA aircraft.

I used 3/8" carbon rods -- INSTALLED permanently into a plywood box into the wing extension. The remainder of the ROD "slides" in/out out duplicate plywood boxes installed into the opposite side. (main wing fuselage)

Q) What suggestions would you have in "keeping the in/out" rods permanently in place while in flight?

See attchment for somewhat of a helping sketch)

marwen1

Laird SS

How about a screw, pin, or bolt through the rod and into something fixed in the fuselage or part of the wing that is permanently attached?

Bruce B.

John 38

Marwin,

with just the short carbon rod at the front, you need to make a strong connecttion just if front of this rod.
assuming there is enough wood in the box around the tube, I would make a small aluminium plate with a screw hole at each end to screw into the box each side, on the underneath of the wing.
John

marwen1

My Feedback: (6)

HI JOHN 38:

Will you try to elaborate a little bit, please. Your suggestion has (I think) some viability.

Keep in mind, my sketch is NOT to scale.

_______________________

My plywood boxes are 1/8" ply -- wrapped around the diameter of the carbon rod, (3/8") and they go from the starting RIB, inward to the next rib in the top unit and to the second rib at the lower unit.
100% epoxied into place. ------ allowing the extensions to slide freely into the open units

_______________________________________

I was thinking of a clear adhesive tape, permanently on top of the MONOKOTE on both sides, then when installed for flight, simply add some more clear tape that joins them together.

Good idea? Bad? ???




Marshall

(marwen1)

Mike Connor

My Feedback: (5)

I like the clear packing tape idea. When put down right you can hardly see it. I was thinking about using tape for securing different wingletts for testing on my delta as the side forces are not that much. I have used it often for tears on my hand launch planes with good success.

marwen1

My Feedback: (6)

Thanks Mike.

Yep! I've looked hard at the "screw-in-the-hardwood" idea, but the tape thing sound far more viable.

Marshall

marwen1

BMatthews

I'd suggest the tab and screw deal instead. Unless you use a lower tackiness tape you risk it lifting the heat sealed on plastic coverings. The extra protective layers of tape don't prevent this from happening.

It may work out fine for a season or two but eventually it'll lift the covering off the unlying wood.

marwen1

My Feedback: (6)

Hi Bruce:

Can you possibly simplify the alternate method for me

Thanks

Marshall

Mike Connor

My Feedback: (5)

leave it to Bruce to find a fly in the ointment.

ArmedZagi

My Feedback: (1)

I'd do something like this. I think its along the lines of what BMathews was suggesting. The rods give it strength and the hardwood tab keep the wing attached. If it were me, I'd probably put a blind nut in there and just use a regular nylon wing bolt. Clean and simple.

BMatthews

BINGO!

Marwen, you'll want to run the bolt up from below so it's not in general view and a 10-32 will be way more than adequite. The tab would run into a little reciever box and preferably tie to a spar or some other stronger point. Perhaps put the tab and bolt closer to the front rod so you can take advantage of the already strong point.

The tape lifting the covering deal isn't just a guess either. I've used it in the past and as I mentioned it eventually lifted the covering. On those models I've had to re-seal the covering a couple of times each over the years. I just dislike iffy stuff like that so anything I've done since uses a mechanical method instead of tape.

marwen1

My Feedback: (6)

MUCH THANKS GUYS! Now that makes sense!

Bruce: If I put a layer of clear glossy tape down --- that is installed permanently and each side has it on it


The tape that would go on/off would be the second layer.

Q) will that 1st permanent layer of tape still comee loose?

Marwen1

John 38

Marwen,
just catching up on this thread - armedzagi sketch shows more or less what I was getting at altho his idea should be built in at construction stage. From your question, I assummed model already built, hence a small metal bridging plate screwed into your ply boxes on both sides of the join on the undrrside - missing carbon bar as that would weaken it

Your opening post also stated " large " wing extensions with substantial 3/8 carbon joiner rods- can you specify how large model is and power (speed ) involved as this will have a bearing on how robust the connection needs to bet to hold the wings together against the resulting drag on the tip wing trying to seperate them

I also indicated that the connection should be just forward of front rod - this is based on the drag on the wing extension attempting to pivot the extension round the bottom corner and the best place to prevent this is to have the tying connection as far forward as possible.

I hope to put some sketches together to post tomorrow to illustrate the above.

Re tape, I use electrical tape to join my glider tip sections together as this is fairly common practice . The drag forces involved here are relatively small.

John

BMatthews

The first layer of tape is still only as good as the grip of the covering material under it to the balsa under the covering. And that ended up being the weak link on my two models. It's the balsa to covering bond that let's go.

marwen1

My Feedback: (6)

Bruce: Now that all makes 100% sense now.

John: This plane is Laddie Mikalowski's FORCE ONE. His original plans was a 36.5"WS

I printed up the entire set of plans with a 60"WS

The ribs break at 17" from the tips --- giving me 34" taken from the 60"WS

That leaves the fuselage and some of the wing a total of 26". Add them all up and we have the 60"WS.

The length of the rib at the split (which is about mid-wing) is 27.5" (before the elevators)

I have a ROSSI .61 (rear exhaust and rear carb) that was bored out by ROSSI to a .81cc

I'm told that I should expect about 18,000 RPM on the test stand. No telling what this is capable of as it unloads.

I know one thing so far, even with the TUNED PIPE that I got from Robert at MORRIS HOBBIES, this thing is LOUD!

John 38

Marwen,

yes it is big and will be fast, with rossi up front ( now I know why you went for 3/8 carbon rods !! )

I attach a sketch of where I believe the best place for connecting strip to be. ( nice dwg armedzagi)

based on holding extension on against drag and also where you are likely to have strongest location - corner between ply box and hardwood face rib (?).

there should be a strong glue joint particularly with the ply box.


model should be really impressive in the air - what speed are you expecting out of it ?[img][/img]

regards

John

marwen1

My Feedback: (6)

HI John:

Not sure if this is important or not but, when I made the extensions, that is the side where I anchored them --- see post #15--- the wing tip on the left of the two images is showing the underside -- hence, the servo .

Flips over and feeds INTO the hardwood receiving blocks in the main fuse.

While we're there, go back to post #15 again, notice that the leading edges of the fuselage and the wing tips are at a slightly different angle of attack.

Air coming down from the nose of the plane via the leading edge is going to be interupted a little due to the foremost point of the extention. Hopefully to reduce tip stalling,

Q) should I have a bit of a larger "plate" (or something) to help with that? or should I just leave it alone?

There is a difference of about 5Ëš angle of attack from the startup leading edge to a more acute angle of the extension.

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Take a look at my avitar. that is CANADA's CF105 the AVRO ARROW. You cannot tell from the avitar but if you look at an top view of it's plans, that is where I pulled the idea from.

In reality, the only reason why I made the change is because if I made removeable extensions (as I did ) I stood a good chance of the total leading edge to not "look " right. LOL Call me paranoid. So, in the grand scheme of things, I just played it safe.

Marshall

John 38

Marwen,

I dont think it matters which side you anchor rods , but I would suggest it is probably preferable to have the heavier (?) boxes inboard and lighter rods outboard giving better distribution of weight/ strength on model.

re your break in the leading edge - if it is good enough for the CF105 ....................

Perhaps some aeronautical engineer out there can offer an explanation of the purpose of the break.

The Vulcan bomber - the recently restored one flew today after 14 years - http://news.bbc.co.uk/1/hi/england/l...re/7049694.stm - had a similar wing shape in that the L/E angle curved back to give more sweepback towards the tip, so you have a precedent for your design

As you have already built the model, there is only one way to go and that is forward

regards
John

marwen1

My Feedback: (6)

John 38:

Ya gotta love ignorance. I made ALL boxes the same size.

Well, it's been an interesting day here today.

Here I am retired and after 2 months of glorious -- doing nothing -- I got bored to tears so I stared to drive courier here locally within the city of Winnipeg, MB. Probably putting about 165 KM per day onto my car.

Yesterday, I had to call a tow truck andx carry my minivan off to my mechanic. Turns out that I broke the timing chain on my Plymouth Voyager van.

OK -- stuff like that happens now & then. All the $$$ I make with my working this job (5.5 hrs/day- avg.) helps to pay for this incrfedible RC hobby.

I'd built the 36"WS version of this plane way back in the late 80's ---TOTAL self taught.

Build it. Fly it. Crash it Repair it. Fly again. Really slow learning curve.

With the advent of this thing they call the INTERNET & the FORUMS --- Holy Cow! What a source of help.

In fact that goes both ways,

Should YOU EVER have need for any of your plans ENLARGED --- I can do them to any percentage you choose.

These SPEEDY printing outfits though can do them fast, but they are not too accurate I'm finding. Our accuracy is within a .15/1000 tolerance.

I think that's pretty close.

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So, while taking a few days off to have my engine worked on, I'll get to trying to finish this FORCE ONE 60, (I guess I'll call it the FORCE 160) a little farther down the track.

I'm at the point where I have to try to tune up the TUNED PIPE. Looks like I need to buy a new TACH

I'd put up some more images but for some strange reason, my computer doesn't want to "see" my digital camera.
I'LL JUST GET A SanDisk that reads the SONY STICK and I can keep on uploading.