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Author Topic: "Novice" Penny Plane by Cezar Banks attempted by a novice... maybe  (Read 9914 times)
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Jimmy JFlyer
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« on: March 22, 2014, 03:04:32 PM »

Hello indoor folks...
So I have finally placed an order from A2Z and will finally take a shot at indoor duration. I want to start out with a thank you to all you folks that helped me with advice in knowing what to get and also helped with enabling me to get it. Serious thank you!!!

I am hoping to maybe get a plane built for the Cloud Busters Indoor Fling in May but I am not holding my breath as my order got held up wtg for some out of stock items.

So I narrowed it down to the Novice and the "2 Cents Plain" by Dave Linstrum. A lot of folks have recommended the Novice and so I want to go for it. But looking at the plan, which seems extremely simple, I see some things that to a newb are not so simple. I will do my build & share it here and of course throw plenty of questions out as I go. I don't want to totally try it alone as I know I will goof it up. I know how sensitive these are to being properly built & trimmed.

It seems that the plan has experienced builders in mind as a few things seem to be left to fore-knowledge.

Looking at the plan the first thing that confuses me is the ribs... 12" arc for the wing ribs & 18" arc for the stab ribs... Can someone put that in laments terms? I am totally unsure of what constitutes this "arc". The plan does not have a template on it.

Then there is "1/8 left turn (rudder only)" ... I see no offset in the boom, nor stab tilt for that matter. It almost sounds like this is describing tilt in the stab ends? Can't see that in the plan as it looks like right angles from the stab TE to the edges... again, this may be obvious to an experienced builder but I am baffled.

And last question for now... the prop... oh goodness this one makes me nervous for sure. Regarding the blades position on the spar... would it be just like it looks on the plan? If this is the case then it looks to be much closer to the TE of the blade. It actually almost looks like if the blade was split into quarters length wise of the blade, the spar would be on the back 75% marker, so 3/4's the distance back towards the TE.
I will be using the prop pitch gauge from A2Z and am hoping that it will help me to understand how to do the 22" pitch that the plan calls for.

Being brand new to this kind of building makes it hard to go by a plan that leaves some things open to interpretation so I am hoping for a little advice on how to proceed in these particular areas.

I will try to add the link to the online PDF that Mike Kirda posted for me in my other thread in the general forum. We'll see if it works. Otherwise I will try to post my pdf if that is possible. This way folks can look at the plan in question.
http://indoornewsandviews.files.wordpress.com/2013/09/inav-137a.pdf

I figured it would be nice if this starts up some discussion abut this interesting plane and of course any advice that anyone could offer will be greatly appreciated.

Thanks for looking folks and God Bless!   Smiley

Jimmy
« Last Edit: March 22, 2014, 04:36:31 PM by Jimmy JFlyer » Logged
Olbill
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« Reply #1 on: March 22, 2014, 06:49:33 PM »

Some quick answers:

12" arc - draw a part of a circle with a 12" radius. That is the shape of the wing ribs. Same idea for stab ribs except the circle radius is 18". Glue your drawings to something durable that you can cut out for rib templates.

My guess about the 1/8" rudder is that the tops of the stab tips are twisted 1/8" for right rudder.

Yes the prop spar is closer to the TE of the prop. Many are actually on the TE.

I would suggest using the full legal 4" for the stab chord to increase the static stability margin. Anything less will make the model harder to trim.
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mkirda
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« Reply #2 on: March 23, 2014, 11:43:20 AM »

http://propblocks.files.wordpress.com/2013/09/bankslpp.pdf

I'm getting pretty good at doing these in Autocad now.
I'd suggest UHU or similar glue to 1/16" plywood, cut close with good scissors, then sand to outline with disc sander.

Regards.
Mike Kirda
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Dave Andreski
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« Reply #3 on: March 23, 2014, 01:11:53 PM »

Mike,
It was very kind of you to draw those for Jimmy. It'll be a big help.
Dave
« Last Edit: March 23, 2014, 01:45:30 PM by Dave Andreski » Logged

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Olbill
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« Reply #4 on: March 23, 2014, 01:43:05 PM »

http://propblocks.files.wordpress.com/2013/09/bankslpp.pdf

I'm getting pretty good at doing these in Autocad now.
I'd suggest UHU or similar glue to 1/16" plywood, cut close with good scissors, then sand to outline with disc sander.

Regards.
Mike Kirda

Mike's method will work well.

I use aluminum flashing material for templates. I spray the back side of the paper with 3M77, stick it onto the aluminum and cut out with tin snips. Then I sand the curved edge with a sanding block to remove any roughness.
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mkirda
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« Reply #5 on: March 23, 2014, 01:43:57 PM »

Mike
It was very kind of you to draw those for Jimmy. It'll be a big help.
Dave

5 minutes of time, Dave. That is all it took. Now getting to where it took me only five minutes? Many hours... LOL.

Mike
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Dave Andreski
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« Reply #6 on: March 23, 2014, 02:01:27 PM »

Mike
It was very kind of you to draw those for Jimmy. It'll be a big help.
Dave

5 minutes of time, Dave. That is all it took. Now getting to where it took me only five minutes? Many hours... LOL.

Mike

Many hours...
Even more appreciated.
Dave
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Jimmy JFlyer
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« Reply #7 on: March 23, 2014, 02:53:34 PM »

Wow, all you guys are greatly appreciated!

Olbill, thanks for that explanation on that arc. I planned on going with the wider stab. Do you think I should go with 4" chord instead of the 3 &3/4" on the '89 plan? Now I am wondering how I might get just the stab tips to twist. More on that ...

Mike, thanks a ton for those templates! That is a huge help. When I print them, should I print them to a size that matches the chord of the wing & stab? So make sure that when I print them the length of the wing rib template is 5"?

Dave, thanks for all your encouragement and help too.

So back to the stab and rudder... tips only, twisting the tips??? The first thing that comes to mind would be to just set the angle of the stabs ends to be offset but the last thing I want to do is defer from the plans. Being a newb the last thing I want to do is NOT build per plans. The weird thing is this is the first LPP plan that I have seen that doesn't have the boom offset or stab tilt.
If I just twist the ends, I am assuming that I build per usual, cover, then make the dihedral but when I glue it to set it I should then "twist the ends" and somehow hold them in position?

Then looking at the end of the boom it shows what appears to be a lift of 1/4", would this give the stab neg incidence? Looking at the side view pic it looks like the top of the motor stick & the tail boom stay level with the bevel being underneath going to the rear. So then is the stab glued to the bottom of the boom or the top?

Sorry for all the questions folks. I am just realizing how vague the pics in the plan are and without actual how-to explanations it is hard not knowing how it "should" be done. That and I tend to be a bit "detail" oriented in how I approach things and with out details I am not sure what to do and certainly don't want to do the wrong thing on a first LPP.

Thanks guys!
Jimmy
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Dave Andreski
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« Reply #8 on: March 23, 2014, 03:47:39 PM »

Jimmy,
Go back and read everything everybody posted.
ALL info is there.
Dave
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mkirda
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« Reply #9 on: March 23, 2014, 04:20:42 PM »

Jimmy,
Go back and read everything everybody posted.
ALL info is there.
Dave

It *is* all there, but not necessarily to the novice eye.

Jimmy, there are two ways to do this. One is build the flying surfaces straight and offset the tailboom.
Or you can offset the rudders by say 1/16" while building the stab and keep the tailboom straight.
Neither one is more right than the other, IMO. Just make sure to build in some stab tilt while building it.
And make sure that there is some negative incidence - You don't want it all to come from the wing.

Some starting points:
1/4" stab tilt
1/4" offset to the left and up.
1 degree downthrust
1 degree left thrust.

If you use a Harlan-type bearing a bit off the motorstick, use hard vertical grain (end grain) to avoid crushing the balsa and wrap it with thread - Kevlar fly tying thread works great here.
Use Ambroid - it can be dissolved if necessary to change the angles.

Regards.
Mike Kirda

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Jimmy JFlyer
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« Reply #10 on: March 23, 2014, 08:02:26 PM »

OK. That's about what I figured on doing, the tilt & offset. I just realized I didn't get 3/16 wood so I will have to hunt the local hobby shop for good wood for the motor stick & boom.

Mike, when you talk about "crushing" the grain on the motor stick do you mean when I wrap it with thread? Is that when I could risk crushing it?
I have both the double end bearings and also the Harlan type coming in my order from A2Z.
I also have Duco that I have been using thinned with acetone. I planned on using it if it will do.

Will try the nearest hunting/fishing goods store for the Kevlar.

Now just can't wait for my order to get here. Might cancel the items they were waiting for if they aren't in over the next day or 2. It was the nozzle caps for the glue bottles. Can probably do without them. I know George sells them too.

Can't wait to get started. I am almost finished with my Flyboy. Just have to seal it & he's ready to test out. I will be itching to build once its done.  Roll Eyes

Thanks for all the guidance guys!
Jimmy
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mkirda
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« Reply #11 on: March 23, 2014, 09:18:24 PM »

OK. That's about what I figured on doing, the tilt & offset. I just realized I didn't get 3/16 wood so I will have to hunt the local hobby shop for good wood for the motor stick & boom.

Mike, when you talk about "crushing" the grain on the motor stick do you mean when I wrap it with thread? Is that when I could risk crushing it?
I have both the double end bearings and also the Harlan type coming in my order from A2Z.

1/8" A grain will be fine typically for LPP - that is what I use. Make it 1/4" high, maybe slightly higher. Don't bother tapering it for your first one - My last one wasn't tapered and it was strong enough to launch at near max torque and still underweight.

I don't have a handy pic, but I offset the Harlan bearing about 3/32-1/8" in order not to have to deal with rubber knots as much.
If you have the grain run parallel to the motor stick, it can tend to crush under higher torque levels. Especially with 5-6# wood. Hence the suggestion to use harder End Grain in this application.
Rock hard balsa would also work.

I wrap with thread for one reason - If the glue/bearing surface fails, the thread will keep the bearing from shooting back and turning your creation into so many useless sticks.

Regards.
Mike Kirda
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« Reply #12 on: March 23, 2014, 09:22:09 PM »

Of course I don't agree with the flat wing and negative stab or the washin in the left wing panel or the usual way of getting left thrust. But I wouldn't want to try to talk you into my deviant ways of doing things.
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« Reply #13 on: March 23, 2014, 09:29:23 PM »

IMHO, you are over-thinking this a bit. If you do anywhere near a halfway decent job, it will fly for a few minutes. Which is quite satisfying.

The Harlan bearing is quite small, but it will have some force on it. I haven't had problems with one of them crushing a motor stick spacer, but it would make sense to make the spacer out of end grain, since  you need one anyway. I don't think it's shown on the Banks plan, but the Harlan bearing isn't terribly deep, so for a model with a fat motor, like a pennyplane, you may want to put a little spacer there.

The prop mounting shown is correct, but not necessary. With most of the prop blade in front of the spar, the blades will bend back and increase pitch under high torque. This means you won't have to back off as many turns to avoid hitting the ceiling. But if the torsional stiffness of the spars don't match, your prop might get a little wobbly.

If the wood you have for a motor stick is too large, it's easy to sand down. Take a sanding block and tape slippery spacers on either end to raise the block an appropriate distance above the work surface. Use fresh sandpaper and don't press down too hard. Clean the dust off the sandpaper often. Always sand away from the fixed end so you don't buckle the piece.


Don't know if I've mentioned the following to  you:
If you haven't read Bob Meuser's No Non Cents article, you may find it helpful:
http://www.rcgroups.com/forums/showatt.php?attachmentid=2294852

Ron Williams' book is great, too:
http://www.indoormodelairplanes.com/
An exceptionally well presented book.
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Jimmy JFlyer
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« Reply #14 on: March 23, 2014, 10:30:20 PM »

Mike, thanks for the motor stick advice. I'll give 1/8 a try.

Bill, I know being a newb & all I should stick to simple methods for trimming but truth be told, I am quite curious to hear about your "deviant ways".  Wink Maybe someday after a successful build or 2 under my belt...

Lincoln, thanks for that No Non Cents article, very helpful indeed. I had actually started looking at that RCG thread shortly before coming here to HP. I do plan on getting Ron Williams book too.
And your right, I know I am over thinking it. I do that often, one of my bad habits.  Roll Eyes

I will initially shoot for just a plane that will fly a few circuits around the sanctuary successfully, then start going for time. I agree, just watching a plane go for 3 minutes would be great.

Regards,
Jimmy

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lincoln
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« Reply #15 on: March 24, 2014, 05:16:00 AM »

If you have room, once you get your plane dialed in you'll probably get more like 5 or 6 minutes.

Save the overthinking until you get to 1/2 gram EZB's. Then you'll need it. Or if you get into one of those events where they use variable pitch props! The delightful thing about limited  pennyplanes is that they tend to fly pretty well without a lot of trouble. I seem to recall that EZB's built to two or three grams are pretty easy to fly also. But not if built at a competitive weight.

Don't wait too long for fancy tools and materials. You can make a fine limited pennyplane with Elmer's glue in a bottlecap, applied with a toothpick. Just freshen it up every few minutes. You don't need kevlar for the wrapping, because it's not that hard to hit the weight. Sewing thread is fine. (Not heavy stuff like carpet thread, just your average or thin sewing thread.) Bare steel guitar string will work for the prop shaft if you're waiting for wire. And so on.
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Jimmy JFlyer
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« Reply #16 on: March 24, 2014, 08:24:00 AM »

I shudder at the thought of sub .5 g planes and covered variable pitch props! At least while build time is few and far between. I watched some vids of indoor last night. Saw a few of Kang & his EZB too... Ah some day. Real life is seriously busy right now with kids & church so I am not able to really devote the amount of time nec for successful R&D so a 5-6 minute LPP will do... that is until the bug bites and I start looking at the lighter ones after getting used to LPP fatties.  Wink

Wont wait for tools. There is thread somewhere in the house. As soon as my A2Z order gets here I will be good to get started as all the items I need materials wise is there. Can't wait!

Back to work... Sad  Wink
Jimmy
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« Reply #17 on: March 25, 2014, 12:00:10 PM »

Jimmy
I see no one answered your question about how long to make your rib templates. I would suggest making them a couple of inches longer than you need. Also hold on to them for future uses. I have a box full of templates for different radii.

When I'm making wings or stabs with chord restrictions I cut a piece of wood the exact length of the ribs and use that for all of the ribs for that wing or stab. That will insure that your wing or stab chord will be the exactly what you want. It will also eliminate having to trim the ribs while you're building which I think is a bad idea.

To do the actual gluing together of the parts I usually will glue one or two ribs to one of the spars freehand. For instance you could glue the end ribs to the LE spar. After they've stuck but before the glue is totally set you can adjust them to make sure they're square to the spar and at the same angle. You can check the angle by laying the 3 piece assembly on your building board and adjusting the ribs so that both TE ends are resting on the board without twisting the LE. Then you can attach the TE spar to the loose ends of the two ribs. This will give you a stable rectangular frame. You can then glue in the remaining ribs.

I use steel nuts to hold the spars in alignment during this process. You can either build the frame over a drawing or use a straightedge to make sure the spars are straight.

Building a model with tapered wingtips and tip dihedral complicates this process a little. The other alternative is a flat wing with tip plates which is much easier to build and cover. But then there are some complications with attaching the tip plates so it's pretty much a personal preference which way to go. Flat wing models are pretty popular and have been very successful.

You asked about 3 3/4" stab chord vs. 4". I would go with 4" but I doubt you'd see much difference in real life performance. Just keep in mind that for the model to be legal it can't be over 5" for the wing or 4" for the stab by any amount. I usually build about 1/16" under the max. Some other people cut it closer than that.
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Jimmy JFlyer
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« Reply #18 on: March 25, 2014, 02:20:39 PM »

Hey Bill,
Thanks for all the advice and explanation on the spars & ribs. You spelled that out quite nicely. That shed a lot of light on doing the surfaces. I will do the tip dihedral per the plan & see how it goes.

Mike posted a link a few replies back to his PDF of the rib templates for the needed dimensions too so I am all set there. Thx again for those Mike.  Smiley

Yesterday I emailed A2Z just to check on status to my order and was told it was set to ship later that day. They replied like less than 3 minutes later. Then I got the confirmation email it was shipped w/tracking #. Won't be long. I passed back and forth a couple emails in the beginning with their sales dept and Karen personally emailed me and added something I forgot to my order. Very helpful indeed.

Wow, I might soon be holding super fragile actual indoor wood in my hands!!!  Shocked  Grin
Will have to make sure to keep that crazy 3 yr old spitfire son of mine on the other end of the house. lol

Thx again for the all the advice Bill!
Regards,
Jimmy
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Jimmy JFlyer
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« Reply #19 on: March 27, 2014, 10:21:36 PM »

Happy dayz!!! My order is already here! Finally got all my stuff and can get started on my Micro-stick and my LPP. I told myself that I would do the Micro-stick 1st since I would be able to fly that right off the bat at home but I really have had this LPP on my mind so will start that one.

I looked through all my stuff and my jaw dropped. Before being introduced to indoor duration I never would have thought pieces smaller than my pinky fingernail would be used in building a plane! I can't believe how little the bearings are. I knew they were small but had no clue they were THIS small. I got a small rat tail file and the thing would fit in my daughters Barbie doll's hands!  Wink

Then wood thinner than paper?! lol And stoked to have my needle cap glue bottles.

So enough silliness. I hope to start cutting wood this weekend. I just had to share my excitement at getting this stuff.

And a new chapter begins... Grin

Jimmy
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Re: "Novice" Penny Plane by Cezar Banks attempted by a novice... maybe
Re: "Novice" Penny Plane by Cezar Banks attempted by a novice... maybe
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Olbill
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« Reply #20 on: March 28, 2014, 09:33:20 AM »

Jimmy
The real exciting part is just around the corner - flying!
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Jimmy JFlyer
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« Reply #21 on: March 30, 2014, 12:05:14 AM »

Just noticing the plan calls for 3/16 motor stick & boom. I only have 1/8 sheet. Would that be sufficient? Or do I need to get my hands on a scale and head for the hobby shop and start looking for good 3/16?

Thx!
Jimmy
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« Reply #22 on: March 30, 2014, 01:11:16 PM »

1/8" wide on LPP will be too weak in twist if you ask me. If you do not find 3/16" you can always go 1/4" and razor plane it down. I can typically find 5-6 pound rather easy at my local hobby shop or craft store in the thicker sizer. Many times a sheet that weighs 6 pound is really half 5 pound and half 7 pound so the 5 pound is hidden in the sheet. Sometimes you have hidden 4 pound in a sheet as well :-)   
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« Reply #23 on: March 30, 2014, 02:00:51 PM »

I agree that 1/8" is a little on the thin side. My best current stick is actually just a little over 1/8" at the midpoint (1/4" high x .140" thick) but it's from an exceptional piece of wood. If you can get your hands on Larry Coslick's Hobby Shopper EZB article there is a great discussion on how to find those hidden treasures. Once you find one be sure to mark it and keep it in a safe place where you can find it again.

Like Don says it might only be a small part of a sheet of wood. When I'm cutting a stick out of a prized sheet I try to make the cut as close to the final shape of the stick as possible to avoid messing up the place where you will want to cut another one in the future. When you get outside that small area you might be looking at heavier wood or less stiff wood or if you're really unlucky heavier AND less stiff.
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Jimmy JFlyer
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« Reply #24 on: March 30, 2014, 02:10:23 PM »

Thx for the advice Don & Bill.
Hmmm, I think I need to learn more about identifying the various weights when looking at wood at the LHS. I was not aware it was possible to have different weights within a single sheet. I'm not even exactly sure how to go about weighing/testing the sheets. Is it just a matter of weighing the individual sheets to determine which is heavier/lighter? But what I really want to know is how to actually  determine the specific weight of a given sheet in pounds. I will go back to the articles from Indoor Duration.com. Fortunately I have Ron Williams book coming. Can't wait to crack that thing open.
For the most part I can tell visually what grain it is. I looked yesterday when I was there at all their 1/32 and they all looked like A/B. I didn't find a single sheet that looked like C. Fortunately I have like half a dozen stores in my area that sell balsa by the sheet.

Just saw your post as I was typing this Bill. It's the Hobby Shopper article I was thinking about. I will check it out again.

Jimmy
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