Mike Smart Designs Electrified Raven 3m build log - RC Groups
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Dec 12, 2006, 10:53 PM
Build Log

Mike Smart Designs Electrified Raven 3m build log

See also previous threads here: https://www.rcgroups.com/forums/showthread.php?t=610239

Tonight I made the root ply rib on the right wing.

photo 2858 - On the left wing, had to add shims so the root would be square to the trailing edge. This will be sanded down. The aft part was 1/8 inch out of square

photo 2859 - adding paint to the wing rod tubes so the root rib cut-out will have the hole position marked when it is pressed on. Right after this the paint bottle decided to orient itself horizontally, also marking half my work area. I had to run the house fan to get the fumes out. After stopping the cussing, I resumed fitting the rib.

photo 2861 - The paint marked the holes perfectly

photo 2862 - After drilling the holes and epoxying the rib on, it is a perfect match. Don't forget to mark the aileron wire to distinguish it from the flap wire.

photo 2863 - the wingtip blanks are glued on. I will carve them out carefully with the Dremel and a drum sander. Note to builders - it would have been better to rough carve these to shape before gluing them on. Then you could have used a belt sander.
Last edited by Tim Pierson; Dec 22, 2006 at 03:15 AM.
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Dec 17, 2006, 08:26 PM

Wingrods, wingtips and root ribs

Had a good construction day today.

First I carved out the curved wingtips. Hobbed them into shape using a 4 inch belt sander, then got close using a 1/2 inch sander drum on the Dremel tool. You have to be really careful not to carve too deep or too uneven with this or else you won't get it smoothed out. I finished the carving with a sanding block with a curved edge.

Squared up the right wing root rib. I had to shim it about 1/8 inch from the center to the trailing edge, and sand and fair it in carefully. Its not too critical since the 1/16 plywood rib levels out small imperfections.

But, blast it, I forgot to angle the wing's root rib for the dihedral. Looking back I know now I should have left them floating until I could measure the correct angle.

I tried calculating the right angle from the measurements but I have forgotten all my trigonometry. So, after much thought, here is the plan:

The fairing ribs on the fuselage are supposed to be made out of 1/8 plywood. I will make mine out of 1/4, and by trial and error trim the side facing the fuselage with the table saw until I get it right. I think only a few degrees will do it. I'll mount the rib to a 2 x 4 to hold it while I trim, then cut it loose. That will be next week's project.

To assist in measuring the angle, I made the wing rods today. They are made out of 1/32 music wire and very strong. Mike's plans include a drawing of how much to bend them and I used that as a template. It worked really well, except I broke the mount on my vise. Time to get a new one, it was 35 years old.

I'm anxious to start making the fuselage. Hope to get to that next week too.
Dec 18, 2006, 11:58 PM

Fuselage root rib construction mess-up

Worked on the plywood fuse side root ribs tonight. The instructions say, ďform the ply wing stub ribs by drawing around the finished wings. Accurately locate and drill the dowel holes, and epoxy these stub ribs in place taking great care to ensure the incidences are identical between the sidesĒ.

In other words, the relative wing incidence is determined by how well these stub ribs are mounted. How am I supposed to do that? Get it wrong and oh well, it was fun building a desk model!

So I came up with the idea to drill the holes in the fuselage larger than the wing rods, and exactly the diameter of the wing rods in the stub ribs. Then after the fuselage is done Iíll put my new, never used-because-I-couldnít-figure-out-how, wing incidence meter on one wing. Iíll jig everything up and glue that side in matching the plan drawing, measure the incidence then glue in the other one positioning it to the exact same incidence. With the fuse holes bigger there will be some room to play until the glue sets. I hope that will work.

I cut lightening holes in the stub ribs. These took out 7 grams between the two sides, but the ľ ply ribs still weigh 42 grams. Ouch! So, back to the drawing board and another trip to the LHS Ė Iíll try 3/32 and maybe 1/8 ply. On second thought, maybe I can still sand an angle into 1/8 ply for the dihedral and have some plywood left.

The wing panels are almost completely done. I still have to finish-sand them before cutting out the control surfaces. The left one weighs 333 grams, the right 336. Amazing! Look at the picture of them together Ė this is going to really turn heads at the field.

I thought you might like to see my hangar. Not shown is the Renny I am building right now as well.

For radios I use a JR783, and a JR 9303. I have most of the planes on 53 mhz and use my ham license to transmit there, so there is never a frequency conflict. But you canít get 53 mhz equipment anymore, so Iím getting 72 mhz for my new receivers. Iíll probably have to convert all to 2.4Ghz in a year or two after they work the bugs out.
Dec 19, 2006, 02:32 PM
I bought a 3M Raven plan from Mike Smart when he was a boy - I was just a little older - Flew it off the line and slope and loved it. Did it all again, greater love hath no man.....Tried different colours but black was best, a raven? BUT what is it doing here in the electric segment?
Dec 19, 2006, 04:09 PM
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Mike Smart's Avatar
Hi Dave,

Boy here - looks like its going to be an electric Raven 3m - all that extra weight


Here's a photo of the original for inspiration
Last edited by Mike Smart; Dec 19, 2006 at 04:56 PM.
Dec 19, 2006, 05:25 PM
Registered User
"....my wife lets me build and sand in the family room."

You have a very understanding wife.

That's a real sharp looking plane!

Dec 19, 2006, 09:47 PM

Converting the Raven to electric


I put the thread here because I am converting it to electric (Sorry Mike). I figure the motor, ESC and battery will add about 16 ounces, or just over 2 oz/square foot. I think the total weight will be around 70 ounces.

I think building the cowling around the motor is going to be one of the most difficult parts for me. I don't know how I am going to do that yet.

Sigh, life at Microsoft and Seattle traffic are keeping me from getting much work done on it for a couple of days. Hope to get a lot of work done this weekend.

Here is a copy of the modifications I am doing from an earlier thread:

I am modifying it in a few ways:

I put shear webbing on both the front and back of the spar on the inner panels, and on the front of the spar all the way out to the tip. That is more than the plan calls for. I figure more is better with shear webbing.

I put carbon fiber on the bottom of the spar on the inner panels.

Converting it to Electric. Fuse will be widened about 1/4 inch to hold batteries better. I will firewall-mount an E-flite Power 15 motor and build some kind of cowl around it.

Adding flaps, so it will be a full-house glider.

Lengthening the nose about 2 inches so there is more room for gear and I HATE adding nose weight to balance gliders. I would rather add tail weight.

Lengethened the aft fuse 1 inch. It is fairly short coupled and this might help, as well as offset the nose lengthening.

Thickened the aft fuse by 8mm as I was worried about it breaking there. I don't want to glass it.

I will glass the wing join at the anhedral joint.

I built-in approximately 1/4 inch washout at the wingtip, tapering to no washout about 10 inches inward. I don't want to lose this one to a tip stall!

I absolutley love the look of the gull wing. I can now see it take shape, it is going to be beautiful. Haven't decided the color yet, probably dark blue or black wings and tail, and white painted fuselage with red or white painted wingtips.

I bought the plans from Mike Smart 2 years ago. They spent one year on the wall in my office at work while I was dreaming about it. now they are in use. The plans are pretty good, and the instructions are concise but ok. You still have to think about it a lot.

I am making all the parts to plan. The sandwich method of making ribs really was a lot easier than I thought it would be. A 4-inch belt sander sure makes it easier.
Dec 21, 2006, 04:38 AM
Registered User
Mike Smart's Avatar

If you mount the motor behind a front former and use a large enough spinner, you won't need to make a cowl.

Dec 21, 2006, 05:51 PM
Registered User
Thank you for your great pics, with them I feel much better when I know I am not the only one who started the builds and left planes unfinished for yrs .
I have an ALMOST done Cloud bound 4, and a 5 yrs old OD STOL plane--Gull, a plane 'designed' around the plan feature in MAN, it is the one really brought me fully back to this amazing hobby, and I have a plane almost forgotten until it was 'discovered' in my dad's house in a recent visit,which was a 'pilot/ok' kit I started the build around 1980-82 , it had been 70% built. I then left this hobby but it was wrapped with newspaper in good shape thou many ribs are rotten, the project .... it'll take lot of sanding works to be done, it gives me many memories good or bad ones though, and I am astonished to see how fast the time flies.
Sorry for my off topic ramblings...
Could you kindly help to show us more pics on the fuselage of your E-Raven? It does look sharp with the cool colour in the picture. Could you tell more about the wings, eg thickness, airfoil...etc.
Thank you in advance.

Dec 22, 2006, 01:18 AM

Fuselage root ribs and motor mount


Great post. I find if you just get started then it is easier to keep going and eventually finish. Would love to see the cloud bound of yours.

Tonight I re-made the fuselage root ribs out of 1/8 ply. They weigh 21 grams - half as much as the 1/4 ones I made earlier. I bought some 3/16 ply and meassured it, it would be 63% heavier than 1/8. So I hope to be able to sand the 1/8 ply enough to get the dihedral right. If I can't I plan to make some kind of ply-balsa sandwich on the fuselage. That will come later after the fuse is built. All becuase I had a senior moment when I made the wings, ignored Mike's instructions and forgot to angle the wing root rib. Read the instructions you foopa.

I also resolve that if I ever scratch build again, to make all facing and mating parts together and drill them together. It is the only way to make things fit.

So I turned my attention to the fuse today. I drilled the holes for the wingrods. I just cannot get the precision I would need, so I drilled these holes larger than the wingrods so I can put a brass tube insert in these ribs when I glue them to the fuse. I am now completely dependent on the incidence measuring tool to get it right. Again, that will come after the fuse is done.

See the photo, I made the front fuse extensions and laid out the motor, esc and battery. The receiver and servos will have to go under the wing to fit, then I will be able to move the battery back and forth about 2 inches to adjust CG. I am extending the nose about 2 inches from the plan to have more room for gear. Now if I can just remember to widen the fuse a little when I lay it up so the battery will fit.

The motor mount plan so far is to firewall mount the motor with a radial mount bracket you see in the photo, then build a false cowling around the motor to streamline it. I think this will be easier than Mike's suggestion, but then I am known to be challenged in making motor mounts and canopy covers. Fortunately I think I can commence to build the fuselage without getting committed to one way or the other. Although I probably should be committed to other places for other reasons.

Maybe somebody can send me a drawing or picture of the best way to mount the motor or design the cowling? I am really worried about the best way to make the motor mount and cowling.
Dec 22, 2006, 01:33 AM

Airfoil measurements

Almost forgot.

The wing at the root has a chord of 10 3/4 inches. At the widest thickness it is 2 1/8. I don't know what the airfoil is. But, building the way I am from scratch it would not have been much more work to use any airfoil you want, make outlines in Profili or other program, and make the ribs. In fact I tried that before I started this plane but in the end decided to stay with what Mike had designed.

I worry some that whatever airfoil it is, it is not designed to work with flaps. I don't know, but it is getting flaps. Of course then I worry too much about everything, especially that maybe I built in too much washout. You can visibly see the washout I built in. One day soon I'll measure it with the incidence meter, at least then I will know how many degrees it has so I can worry, with numbers.

I guess after losing that Thermic Traveller in my hangar photo to a tip stall I am spooked about washout (ok, it was a more complicated pilot error than that. I had mixed in down elevator when the motor comes on, hadn't tested it yet, made a too-low approach and turned on the motor and when it dived I pulled up elevator and left rudder - classical approach stall-spin. That plane is rudder - elevator only, and short coupled so it was an impossible situation to recover from. All because I was trying to avoid hitting the top of the sani-kan at our field {the only object in either direction for 50 feet}. I probably would have missed it anyway. Snapped the fuse in half in the aft section. The plane might be fixable someday)

Dave if you are interested in an unfinished Cloud Bound 4 left wing with a Tim-built 100% beefy spar, that is horked up a little but may be serviceable you can have it. Someday I hope to start over on the CB4.
Dec 22, 2006, 01:44 AM

Airfoil correction

At the widest thickness it is 1 1/8, not 2 1/8. Time to stop tonight, I cant even use a measure stick.
Dec 22, 2006, 02:24 PM
All airfoils work with flaps - but some a lot better than others! - Mike's original was always rock-steady in all attitudes. I did add ailerons (too small) from, in those days,a central servo which did upgrade the roll rate. Now, with mini servos, I think I would have gone for flaps, taking great care to test at a good altitude! and keeping them to the inner panels only.
Dec 23, 2006, 07:38 AM
Registered User
Mike Smart's Avatar

Those splices in the ply sides are bad news so near to the nose

Also, I would have thought you would be far better using an inrunner brushless motor and gearbox. For that size model, maybe a Kontronic Drive 501 set or maybe a Drive 502 set with 18.5" x 12" folding CAM carbon prop blades.

As I said before, if you mount the motor/gearbox behind the nose former and use a large enough spinner to match the width or height of the fuselage, you won't need to worry about a cowling. Cowlings are virtually unheard of on an electric glider.

Dec 24, 2006, 02:35 PM
Registered User

I am quite agree with Mike's point above the option of motors, an in-runner has tons of advantage over outrunners unless you are building larger scale ships. Otherwise it will definitely affect the overall outlook to some extent,I have just found a thread with your post of the raven with an ARC fuselage, it is as cool as the one in the photo of finished one. With a widened or 'cowl like' things dangling in the nose is ....

By the way, I personally like the Kontronik's products so much after I had acquired 3 pcs of their older BL series geared F5B motors (kv5250) and I have been using them for 3 yrs in a RW2 as a 7 cells class, and one in a 3M mistral mouldie with only 7-8 cells packs. It could take the abuses indeed, (170+A, 3 sec/8 sec). And their 'new' FUN series are equipped with segmented/ Ni-electroplated are said to be able to increase the eff some up to 10 % and work ok in partial throttle management, with such 'improvement' make them more versatile, eg able to use it in sport planes in which most of flight time are just run on partial throttle.(like C series of Hackers, which are advertised good for SPORT PLANE usage under partial load, ie: not like ON/ OFF option prefered by most of HOT LINER people ) .

And the suggestion above posts should be the right one to go for, I have a similar one fun500-24+4,2 (or 5,2 forgotten) using in a older type hotliners, with 4s3p Conion, (or sometime with 10IB3800- 4200 or ) at a AUW>=2,5kg , it will rocket like no tomorrow.

Also, attachments below may be interested or give some inspirations.
Last edited by C-MIC; Dec 25, 2006 at 06:43 AM. Reason: upload pictures , done this time.

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