Revy

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That gave me a good start on ideas, Tom! Between yourself, the PA Extra 260 and Deadeyes wickedly cool mount, I came up with something like this work in progress...

Revy

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Soooo, any updates on your build? i wanna see

Revy

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I think I got the motor box almost sorted out. I hope that it will be stout enough to handle the P160. We shall see.

I shear pinned the laminate tab to provide a bit more holding power. I must redo the top 1/8 ply brace as it isn't as snug as I'd like it to be. I'll 'glass the box at the motor mount and the firewall.

Not too shabby for a bunch of scrap material. (Pics all dry fit.)

twn

Looking good Jason!

Be sure to glue that thing together with 30 minute epoxy. You could even wrap some fiberglass/epoxy-zpoxy around the joins to give it added strength. Pin every join with something like 1/8 dowl or carbon and epoxy. With the fiberglass/epoxy/pins it will be bullet proof!

When you gue it to the plane use gorilla glue. Read the instruction as it expands and can be a pain to use but it will be the strongest bond to foam. Plus pin the fire wall to the plane with some thick dowl. sink the dowl in as far as the foam will allow. More gluing surface equals a stronger bond... We don't want that power 160 pulling off the front of the plane at full throttle.

Revy

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Put it together with 30 minute epoxy.

I wish I had a that woodpecker tool. I had taken a T-pin and made a million tiny "pecks" to every surface that mated. Epoxied applied the same way, letting it soak in before I joined the pieces. Clamped it and after the epoxy set-up, I went an took 1/8" CF rod and pinned the box where ever I could to reinforce it. Used over a foot! Thats an 18 x 6 Zinger for mock up.

Now to get on with the wings now the re-engineered power plant aspect is outta the way.

cap10b

Revy,
Ok The Zimpro Cap21 has flown in her new colors, Today not less than one hour ago.

Winds were 13-15 mph
72 degrees
Sky - overcast
Slight SSE cross wind.

BH-50 swings a PK Plus 20x10 at 6750
dual Lipo main batts, with Dual Sky 8amp Regulator
Lipo and MPI 6 volt regulator on ignition
JR 126MG analog servo on Ailerons and Elevators
ATX 94162z rudder.
ATX 94741 std analog on throttle
Dave Brown 3.5 spinner
All up weight - Dunno guessing 17.5 lbs.

Flys great, no bad tendencies, landing smooth and predictable, roll out and taxi easy and no problems.

Now the DANG THING IS FOR SALE !!

JDS

twn

Looking good!

Jason, a suggestion. You might want to think about closing that motor box in a bit more especially around the motor area. There will be a phenomenal amount of twisting going on especially from quick transitioning from low to high throttle. Carbon pinning alone won’t stop it. That motor might be able to twist it in to pieces if you don't. I bet it has similar torque to a 40cc gas! (Probably closer to a 50cc as electrics have incredible immediate torque.) Most gas motors use aluminum rods ½� diameter with 5mm bolts on each end to mount the motor which kills most of the torque. (I can still see my dl50 torquing even though it is tight!) There is lots of strength down the sides which is good for direct pull from the body but putting more meat into the front of it will kill the twist from the torque. I posted a pic to help u understand what I mean. I drew in a hole for ventilation.

I would also fill in the top of the mount (looking at the back side of the pic)


I would even go as far as wrapping the whole mount in 2-3 oz fiberglass and 30 minute epoxy.

Revy

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Thanks, Tom. You can tell it is way stronger completely boxed in. I took more scrap and laminated light ply to form rabbeted panels to enclose the box. Not gonna twist on me now. I'm toying with putting the ESC underneath the box to put it in direct airflow, rather than route cold air into the fuse.

The wings are coming along. I was going to use four CF square tubes but 4 were too heavy. I am using two CF tubes 30 min epoxied on the bottom and the stock balsa strip on top of each wing. When I saw Deadeye's wings flappin away during taxi, I knew they needed to be stiffened up. These puppies are not goin flex much at all!

The instructions make no mention of the 1/16 ply hinge anchor blocks that are to be installed to beefen up the hinges. I noticed it on the full size plans when I figured out that the Robarts they supplied me with were way larger than they mentioned. Like 1" longer and a 1/16 larger in diameter! Not to big of a deal, just more fartin' around on shortening them up a tad on the aileron side.

I had the spare CF tube sitting there in front of me when I had an "a-ha" moment. The aluminum tubes that hold the horizontal stab are almost the exact length of the left over CF! A meant to be mod?! At the longer length, they are 1 gram heavier.

Revy

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I got my West Systems resin / hardner and their pumps yesterday as well as some 3/4 oz cloth.

I was wondering on how much material I should remove from the control surfaces to allow for the thickness of the 'glass to still allow adequate clearances on my covered hinge lines. Anyone know how much should be removed? My guess is1-2 mm per edge, but set me straight if I am wrong.

twn

I doubt you will need to remove any. The 3/4 oz cloth is thin like paper...

Remember go thin with the epoxy. More won't add strength, only fill the weave or you will regret it! Don't try to fill the weave with one coat either...

3 playing cards glued together and used to apply 1st coat is to adhear the fiberglass, second with a 4" roller cut down to 2" to fill the weave. Don't sand into the fiberglass anywhere. Only sand lightly between coats just to knock down the bumps and giblets. Only do a 3rd coat if needed. Resist the urge if you can.

FlyingTyger

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Awesome build Revy. Its cool to find someone else building one of these old school aerobats.

Revy

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Thanks for the words of encouragement! I just might be building the last one. I do believe it to be one of the biggest "foamies" I hope I'm doin' it right .

As far as progress goes, I got a fair bit done. I put a full piece of 1/16 ply on the rudder hinge line just outta pure laziness (I had cut soo many of those other ones) but I think it will end up being a blessing on those not so perfect landings. No finish 'glassin' yet. Practiced inside the fuse first using the West system. I 'glassed from the fire wall back to the rear bulk head. Made a couple minor errors but thats why I started on the inside. I was hoping to reienforce the bottom especially where the gear sits.

Setting the dihedral was a bit of a PITA as I do not have an 8 foot table. I did one side at a time repositioning the fuse to get the other set. Twice the amount of set up time and quadruple the anxiety of I hope this werks! It did.

Then I figured out how much to elevate the elevator servo off the tray to clear the rudder servo sitting in its own box on the floor. I thought of just sitting the servo ontop of the tray and boxing it in, however I am gonna need to get my mits inside to swap out batteries, so accessability played a factor. I added a couple of 1/16 ply strips on each side of the maple gear blocks to allow the servo to sit in that channel. The servo tray got some beefing up as well after re-positioning the servos for a more efficient aileron throw. I will place the reciever in the left side of the fuse as well to keep the right side clear. The elevator control rod was reinforced using 1/8 light balsa ply using the same little cable spiggot protectors to help in keeping everything sliding smooth and quiet. An awful sound was made when the fiberglass push rod rubbed up against the ply only to be amplified by the foam fuse.

The CF tubes for the h-stab needed to be shortened a tad, but slid in-place of the aluminum tubes without much difficulty.

Now to figure out a battery tray (box?).

twn

Very nice Jason!!

Revy

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Thanks Tom.

I narrowly avoided disaster last night! I found out how volatile chemicals can be on foam. I used some Evercoat Poly-flex flexible polyester putty to fill in a small depression in the CF spar channel. Within a couple of minutes the foam started to swell and took on a football / basketball rawhide texture! I quickly scrapped off what I could in a hurry! I think the fact the Evercoats flash time is so fast that helped in keeping the damage to a minimum. Both wings saved! A little elbow grease and a longboard made things look good again. Almost blew it before I finished, pheww.

Edit: BTW I weighed the fuse w/ aluminum gear (1.37 Kg), the wings (1.1 Kg) the H-stab/elevators (172g) for a total of 2.62 Kg sans electrics and finish. Not to bad soo far.

twn

Try a thin wipe of gorilla glue, it sands like foam. u can also use a very small amount of epoxy and a whack load of microballoons (and/or talcum powder if u have it). if u keep the epoxy to an extreme minimum it will sand nicely. Balloons and 5 minute works great on small divets. mix the 5min with about 12 very quick vigorous circles and then quickly put the microballons in until it is super thick then apply, 30 min later can be sanded if your environment is warm enough. This won't work if you are trying to fill a long depression, well it will if you leave the mix some what wet but then it is very hard to sand on foam. (don't use 12 min with balloons, it sucks don't know why)

Resist the urge to try to fix every depression. It is going to add weight and you will be chasing depressions after you glass. You will see them when you prime. I won't be a perfect job... perfection will add weight. A good place to completely ignore imperfections is on the bottom.

A good way to keep it nice is to try to do the surfaces in as few pieces of fiberglass as possible. Seams are hard to blend.

Keep in mind planes like Stacy's composite (extreme-composite, krill etc...) are done COMPLETELY with perfectly shaped molds and the fiberglass is 3/32" thick so there is a lot of meat to work with no inside framework to weight it down with. When the molds are perfectly shaped the skin comes out almost ready to be final sanded and primed.

When your sanding to good finish use the blue masking tape place around the area being sanded. That will keep the sanding to the area u want... always try to use a sanding block. Paper in hand makes odd shapes on the surface. I just use some rubber cement applied like contact, some on the paper and some on the block. easily removed too. Get your self some great planes sanding bars. I have a 6" 12" and 48" that i use profusely. Lester has them. Don't bother with the great planes LE/TE (leading edge / trailing edge) sanding/shaping bars they suck.

For larger holes in foam go get some of that foam they use to fill doors jams and window frames. That stuff is sandable too. Best to try on a small area to make sure it won't destroy...

Revy

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I have got a lot of those goodies from Ron's stuff, Tom, even that dorky forming tool from GP, lol.

Gettin' the courage up to do the next part.

I was wondering on how to get the cloth on. I was thinking on doing it in three main sections on the fuse. Each side and bottom overlapping on top of the turtle deck as well as the vertical stab's LE and the two bottom edges on each side.

For the wings and control surfaces I'd do it in two parts, top & bottom. Is there a better way of doing it that would be a good technique for a beginner? I have 'glassed car parts and speaker boxes in the past, but not with such fine single application tolerances.

Maybe I'll start with the rudder as I do have a spare!

twn

Well first things first. It is your first glassing. You will probably goof it up a bit. Not a big deal. The thing to remember put the seams on the places where you can feather edge it the best with little added weight. Like the leading edge of the rudder. Only over lap the fiberglass by 1/8" and where ever the over lap is be sure to sand (prior to epoxying second piece) slightly into the glass. You can achieve this buy using masking tap where you don't want it sanded. This will loosen the strands creating thousands of little fingers and create a small but damn strong join (over lap). Plus with the join on the leading edge u will only need about 1/16" of feathering to smooth the join.

I would do it like this:

Fuselage/fin – 4 pieces of fiberglass, (2) 1 for each side of rudder placing a 1/16� seam the seam right at the base of the fin. (2) 1 for each side of the fuselage. These are big jobs only mix a bit of epoxy at a time.

Wing – just like you said, (4) 1 for each side. Again use the ca to hold it here and there.

Normally on the trailing edge of the rudder you would do it the same as the le but with this cap i bet the rudder is sunken in to be more scale like. On the te of the rudder don't bother with an over lap just bring the edge together right at the 90 degree.

With fiberglass you can force it to be held into odd places by using a tiny bit of foam safe ca and "tacking" it here and there so it is tightly held against the surface of the foam or edges prior to epoxy. This will also reduce the amount of epoxy used. This will allow you to hold the fiberglass on to convexed places. Just put a drop on the fiberglass let it soak right through, even squish it a bit with yer finger and hold the fiberglass against the foam with a pin or such and hit it with the foam safe kicker. zap! LOL neat eh! Heck you could do the entire leading edge of fiberglass over lap with tiny bits of foam safe ca. epoxy will grab to hardened ca.

With tacking the fiberglass in place with ca you could quite possibly use a roller for the first coat too. This will reduce the pooling of epoxy and reduce sanding…

Only do 1flat surface of glassing at a time though so the epoxy can relax flat.

Revy

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I was thinkin' it was goin to be harder than it is. A little pre-planning and a good substrate is helping out big time. The sanded foam soaks up the West product so the first application makes the 'glass look satin cloth like. I am using a 4" foam roller cut down to two inches to apply the West and then lay the cloth down and sqeegee the cloth with the playing cards. Works like a charm. The second coat I applied to the fin and h-stab's bottom gloss it up as it fills in the weave. Thanks for the advice. I am gettin' stoked!

twn

don't do any second coating until the entire plane has all of the fiberglass and first coat on.

btw you want a lot of fiberglass showing on the first coat. the more you try to put on on the first coat the more the foam will soak up = more weight. go thin. Remeber it is only to adhear the fiberglass down.

Revy

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All of it is barely soaked fabric looking with good adhesion on the initial application. I only second coated the H-stab and as they are basically done. Besides I had a bit of the West left with no other pieces ready for covering!![X(]

twn

Something else that works is using a foam safe contact cement spray. Spray only the foam and then the fiberglass will stick to the glue then epoxy. This also works to keep the fiberglass against the foam prior to epoxy. Just a very light spray. I found that elmers can that is white and blue and the glue sprayed out is clear/white works nice on foam, just light sprays though as heavy ones will eat the foam a bit.

Revy

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Well I did add a bit of weight to the fuse. After 'glassing It is almost 200 grams heavier! My initial application didn't go as far as the ones afterward, lol. You do get better at it with practice. I started on the bottom and I think I may have over soaked it a tad. The balance I had when it rested on the flat motor box is now bottom heavy for sure. Maybe I can lose some weight from the gear by going composite. We'll see how it pans out. I did the fuse in 3 sections and the fin in 2. The rudder is half done.

On the tail there is a linkage access hatch that I cut the ply cover out and placed it on top of a piece of an old zip-lock bag to form a stepped hatch opening. This will allow it to sit flush and is a little more durable when the screws are foam-safe CA'd into place, I hope.

The wings are coming out better than the fuse. I like what I see so far anyway. I was thinking of leaving the ailerons unwrapped as my clearance is tight enough. This should be ok to just prime and paint them along with the rest of it, right?

Revy

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Anyone ever use these?...

http://hobbyking.com/hobbycity/store...00mAh_5S1P_40C

I can get 4 for the price of 1 here!

Also I was looking for cockpit floor graphics. Where would I find one to paste onto the floor of the canopy?

I thought I'd go with a Tru-Turn Big Bird 4" 20x10 pitch spinner as it would be way better than the "best used as a paperweight" spinner that came in the kit.

twn

If you plan to paint the control surfaces you will need to glass them. But if you are doing a color that is matched by ultracote (or other covering) then just use covering for the control surfaces...

From what I can see in the pics it looks good so far!

Glassing will be heavier than covering even if you go as light as possible. Just wait untill you have the paint on!! If you have too much on in places you should try to sand it off unless it has collected under the fiberglass.

Revy

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Guess I'll have to try and glass the ailerons as well.

The rest has been relatively easy, just be patient and the better the light the better the results. I work in a basement, but when I bring it up to daylight I can see all the small imperfections I could have done something about. I had a large low sitting bubble go un-noticed until I saw it the next morning. I cut it with a sharp x-acto pizza pie like and it lay down nicely when I second coated the fuse. There is more than a few small dents n dings that'll have to be filled in. I can't be too picky as it is foam and it will ding up over time, I'm sure.

The little 2" foam rollers are a bit pricey but werk awesome. I got a little matching tray that is perfect for this as it cleans easily. Two pumps of each of the West cans is a good amount to "work" with at a time. Three is too much as it will thicken too soon if you have multiple pieces to work with. My second coat on the bottom of the wings, fuse belly and control surfaces was prime example, not only was it too much for starters it got to thick to work with the roller. It started to pick up the cloth!

All said and done, I think it looks OK. When my camera charges up I'll take a few pics.