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TWIN FEVER !!!

Old 02-27-2008, 06:40 PM
  #51  
KidEpoxy
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Default RE: TWIN FEVER !!!

Efficiency be danged, MAS 6x4 3blade !

Its a twin, give it some props that look right for a twin
Old 02-27-2008, 06:51 PM
  #52  
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Default RE: TWIN FEVER !!!


ORIGINAL: KidEpoxy

Efficiency be danged, MAS 6x4 3blade !

Its a twin, give it some props that look right for a twin
Better cut it down to about 4 to 4.5 inches. That's a heck of a load for an .049 or .061 that likes to rev. Saw a bit off the nose and it might start to look like a twin Convair Pogo..
Old 02-27-2008, 07:22 PM
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Default RE: TWIN FEVER !!!

I built about as streamlined a plane for the .074 as you could get, put a oversized venturi on it and ran it on bladder. I tried every prop from 4.5x4.75 on up and couldn't get much speed out of it, but was able to kill overall flyability very well. Unless you were to grind the case down and get the engine really singin' with some mods, speed with .074s is kicking a dead horse. I have a few .061 powered planes ready to scramble when a serious .074 powered job comes a callin'!

By the time I found a prop small enough to allow the .074 to get into a happy zone, it might as well have been put on a smaller and lighter .061 in a smaller plane. The power / drag / speed formula favors less drag over more power by a factor of 3.
Old 02-27-2008, 09:29 PM
  #54  
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Default RE: TWIN FEVER !!!

Piggy,
I just went through my super secret stash of wide blade Cox gray props and I have three 7"x 3.5", two 6"x 3" and one 5.5"x 4". You can't have the 5.5x4. I am going to make up a mold from it so I can make new carbon fiber clones; as I don't think there are going to be any more of the wide blade Cox gray props made. You are welcome to the 7x3.5 and/or the 6x3. Could even work out an arrangement to make up a mold from your model after you get it flying like you want. That plane cries to be molded in black carbon fiber with just a clear epoxy finish. You will be able to see what my CF fuselages look like in a couple of weeks. Since I don't have it done yet I guess I will let the cat out of the bag. Will be sending you one of my Sky Terrier fuselages to play around with. Go to the field with a couple fuselages and two of four sets of pluggable wing panels and you are ready for a day of hard combat. each wing panel has its own miniature servo and self contained linkage so replacing one or two panels is really only a couple minute process. If something gets smashed just pull another arrow from the quiver and hit the skies again.

[link=http://www.rcuniverse.com/forum/m_1452648/anchors_1452648/mpage_1/key_Sky%252CTerrier/anchor/tm.htm#1452648]Sky Terrier Contest Entry[/link]
Old 02-27-2008, 11:03 PM
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Default RE: TWIN FEVER !!!

Steve, that's very generous considering that 7x3.5s are going for about the same amount as dinner for 2 at Azteca. You could get $40-50 for the lot and I could break all 3 of them in 15 minutes....I think you should just sell them on E-bay.....I'm happy with those $2 APCs, no remorse when they snap.
The C/F fuselage would be most appreciated, used, raced, thrashed, etc.! I'm sure I could learn alot from just having it in my hands to study. That's how I learn best.....from stealing ideas from everyone else.

Here is another 2-3 hours worth of wood removal. $10 worth of balsa on the plane, $20 worth on the floor.
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Old 02-28-2008, 12:16 AM
  #56  
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Default RE: TWIN FEVER !!!

Close up shots reveal more work is needed, so here are more "distance shots"
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Old 02-28-2008, 12:33 AM
  #57  
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Default RE: TWIN FEVER !!!

"Wild Gooser" ?
Ralph
Old 02-28-2008, 01:34 AM
  #58  
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Default RE: TWIN FEVER !!!

Did you run rib capstrips over the spars, then capped the spars to match?
Or are those Sub Skin level spars?
Maybe its just the photo, you got a close pic of the capstrips we can oggle?
Old 02-28-2008, 01:54 AM
  #59  
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Default RE: TWIN FEVER !!!

KE, the capstrips just fly over the spars. Capping the spars isn't a bad idea, it would save me the frustration of accidentally nailing the monokote to a below grade spar. Only rookies do that, though
Over in the Extreme Speed forum there is a shot of a good looking SR71 covering sceme that looks like silver on top with flat black on the bottom and some small % of black on the top. Might be the most functional way to go? Gotta come up with some CIA insignias, where do you find those [8D]?
Once this plane is done, I'm going to have fun flying it over a local commune full of paranoid 60 year old hippies up in Arlington Heights...might have to try those Flyquiet pipes out?
Old 02-28-2008, 07:26 AM
  #60  
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Default RE: TWIN FEVER !!!

Hot dang! That bird is looking awsomer and awsomer!
Old 02-28-2008, 11:59 PM
  #61  
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Default RE: TWIN FEVER !!!

Today was a landmark day in the "programme", the fin / rudder assemblies were installed without incident. The angles were set with a right triangle shooting off identically placed marks on the wing. Too easy.
The fillets are strips of blue foam stuck on with 3M77 and sanded with paper wrapped around a dowel. A minimum amount of spackle is needed, but the foam blends to the wood very nicely. A coat of epoxy to seal the foam goes on next, then a layer of cloth and more resin to give the plane a tough skin where it will be rough handled.
I think the finished weight will be well within what a pair of .074s can carry vertical, and the plane looks like it might balance with just proper battery placement. Good!
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Old 02-29-2008, 08:49 AM
  #62  
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Default RE: TWIN FEVER !!!


ORIGINAL: combatpigg

The fillets are strips of blue foam stuck on with 3M77 and sanded with paper wrapped around a dowel. A minimum amount of spackle is needed, but the foam blends to the wood very nicely. A coat of epoxy to seal the foam goes on next ... <snip>...I think the finished weight will be well within what a pair of .074s can carry vertical
Ain't foam great!!?? I've been using it more and more and building a few foamys. It works so easily and if you screw up, it's not like losing $3 of wood and 30 minutes sanding; more like 3 cents and a few minutes of work time. My primary building tool is an old fashioned carbon steel butcher knife.

I can visualize that plane flying horizontal for about 100' then pointing the nose up about 80 degrees and disappearing near the speed of sound! I still have your Mustang SWR video and watch it occasionally just to get the juices flowing.


Old 02-29-2008, 11:30 AM
  #63  
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Default RE: TWIN FEVER !!!

Dear CP, Chuck, or Piggy (which do you prefer? For myself I'm used to being referred to as EL Magnifico but you can call me anything - except "late for dinner"),

I am becoming more and more addicted to foam (as a building material - I tried freezing some as a substitute for ice cubes but the little chunks just floated on the top of my Southern Comfort and I nearly choked on the darn things).

Anyway, I'm too lazy to read all of your earlier posts so if I'm asking you to repeat yourself - tough nuggies.

I have used water-based polyurethane (WBPU) to stick the FG down and to fill the weave. It comes out somewhat softer than epoxy or resin when cured but its definitely lighter. For 10 points, do you use WBPU? For 17 points if you do have you found a magic hardener? 25 points will be awarded if you have found "the best" brand of WBPU? 13 points for what you use for a final finish coat. If you score more than 38 points total I'll share one of my many beauty secrets with you.
Old 02-29-2008, 11:41 AM
  #64  
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Default RE: TWIN FEVER !!!

I know autoshops use heat rooms to dry painted cars, ala Baked Enamel,
would any of our finishes come out better if we dry/cure them in an oven?
(or devious ovenlike apperatus)

Not really practical for them .91 planes, but we are 1/2A and can do the unthinkable.
Old 02-29-2008, 05:24 PM
  #65  
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Default RE: TWIN FEVER !!!

Hi Andrew...yep, try to find real light balsa block anymore. I haven't seen real light stuff in quite awhile. The only trouble with foam is putting a hardshell finish on it.
Ye olde Mustang is still good to fly, you just have to remind yourself to breathe every 5 minutes or so. That plane has a foam upper fuselage and it is getting a little bit lumpy, but it has served its' purpose pretty well. The original HS 55s just got changed out for 65s. Imagine all the G-forces those HS 55s withstood?

RLF, I tried WBPU on cloth but didn't think the sanding of the seam edges went very well, it got fuzzy. Epoxy isn't any picnic either, it seems to take forever before it is set up enough to sand without being gummy. I like polyester because it gives the hardest shell, but can't touch foam with it. Foam will soak up epoxy resin like a sponge on the first filler coat. Laying up cloth without filling the pores of the foam first is asking for incomplete adhesion. Is there something that you can lightly spray onto the foam [like maybe WBPU] to seal the foam without gaining a lot of weight?

KE, when I was a kid we built those plastic model cars and one of the tips for a glossy paint job was to use a hairdryer for curing. Our model planes can't be painted "hot and heavy" like you would a show car or they would gain too much weight. The secret to a light and shiny job is to wet sand between light coats until you get a nice result. I think white primer followed by silver will give the top color coat a vivid look. If you are shooting out of a spray can, one tip is to warm the cans up to get the paint to flow out and give a fine mist.
Old 02-29-2008, 06:07 PM
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Default RE: TWIN FEVER !!!


ORIGINAL: combatpigg

I tried WBPU on cloth but didn't think the sanding of the seam edges went very well, it got fuzzy. Epoxy isn't any picnic either, it seems to take forever before it is set up enough to sand without being gummy. I like polyester because it gives the hardest shell, but can't touch foam with it. Foam will soak up epoxy resin like a sponge on the first filler coat. Laying up cloth without filling the pores of the foam first is asking for incomplete adhesion. Is there something that you can lightly spray onto the foam [like maybe WBPU] to seal the foam without gaining a lot of weight?
I had an old foam wing that I tried some testing on -- treated each panel differently. I took some lightweight DAP spackle and thinned it down with water to a thick cream consistancy, then painted the panel with a foam brush. It went on pretty well and filled in the porous portions of the foam. I sanded that down (it needs to set up long enough so its not gummy) and added enough coats so the foam was not porous. The filler in the lightweight spackle may be microballoons since it floated if I added too much water. Once it seemed to be fairly smooth, I came back with Minwax WBPU. Found out later that Minwax is not fuel proof. I've also tried .5 oz glass and WBPU -- it added a lot of stiffness, but was a little heavy. I didn't try it, but mixing lightweight spackle into WBPU may improve filling and save a lot of weight.

I've also been using DEFT lacquer sanding sealer on wood -- it's light, seals the pores and leaves a hard finish, but attacks foam. If I could figure out how to lay down .5 oz cloth and seal the foam, then come back with the sanding sealer, I think it would fill the weave and also be pretty hard.

I think BEHR WBPU is supposed to be fairly fuelproof and may work better.
Old 02-29-2008, 06:47 PM
  #67  
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Default RE: TWIN FEVER !!!

Andrew at least you've taken the time to experiment. I've never had the discipline.
I just picked up a tip to save weight when glassing balsa.....use Balsarite for the filler coat. Nothing is lighter or seals as well in one shot.

I've considered using a medium build up of 3M77 on foam to limit the amount of resin that soaks away from the cloth. If this works, there won't be any need for a primer coat of resin before glassing. I think it is time to experiment, plus prove whether or not this old can of epoxy resin is still good.

Ray, I've had great looking results with WBPU and silkspan over foam, just remembered that. I've never done much testing with it, if it aint fuel proof, it aint fool proof enough for me. The only polyurethane type paints I know of that are impervious to fuel are the kind that will make your future great-grand children be born blind if you take one whiff.[8D]
Old 02-29-2008, 08:34 PM
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Default RE: TWIN FEVER !!!

A. Spackle (thinned or otherwise - I forget) over/in foam cracked on me one time and showed up eventually under the covering - almost like a wrinkle. Euch, I hate wrinkles (I see enough of them in the mirror).

2. Spackle (I use the lightweight stuff like everyone else) does shrink and I always sand off the first layer and apply a second automatically (no I don't spread it very thick at all - gimme a break).

III. I sealed the edges of FFF with thinned epoxy satisfactorily on last Summer's diesel experiment (still OK). Epoxy seems to be flexible enough to hold up on light structures as well as withstand the rigors of er, unpredicted ground contact.

Four. I have not tried tissue covering over foam. Oh boy a new gimmick to look forward to. (Tissue over laminating film gives a tough old-timey look - alas heavy).

Cinco. I have made a couple of false starts on a project trying to take advantage of the best attributres of balsa and FFF. Youse-all have just stimulated me (oooh, giggle) to keep on truckin'.
Old 03-01-2008, 01:12 AM
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Default RE: TWIN FEVER !!!

I used silkspan over foam applied with WBPU, then painted with one of those "iron on film brands" of paint. It all looked good till I pulled an alldayer with CP and it bubbled up in the sun. Note sure but maybe the paint got to the foam?
Old 03-01-2008, 01:31 AM
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Default RE: TWIN FEVER !!!

Jim, is that little sucker still with us? I really liked it, but don't remember if it ever "got on step" with a good run?
I finally got a nice enough day to put the newest GLH in the air with a "Toaded" BigMig......it ran real good, good enough to throw a blade off a rubber 5x3. The first time I ever saw that happen. The engine ran unbalanced for a second, then there was a 2nd POP noise, then silence. The engine tore out the firewall from the sides, even though they were glassed. I got to see it fly for about 30 seconds. It landed nicely and awaits some more glue and glass before it is ready to roll.

I think trapped gasses cause bubbling with your plane when exposed to the heat......if the first coat hasn't completely gassed off before the 2nd coat, then you will get bubbles. Some C/L gurus wait a few weeks between coats of dope, [but those guys are paranoid, obsessive, detail freaks].
Old 03-01-2008, 11:27 AM
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Default RE: TWIN FEVER !!!


ORIGINAL: combatpigg

. . . completely gassed off . . . .
Somehow I thought of V** when I read that. (Now you know I would never name actual names in a situation like this - to protect the innocent ! like they say).
Old 03-01-2008, 07:03 PM
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Default RE: TWIN FEVER !!!

Ray, the way I understand it, Vic was studying to get into the priesthood until he first ran into you?
Old 03-01-2008, 09:04 PM
  #73  
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Default RE: TWIN FEVER !!!

We got it screaming pretty good with the TD up in Canada, but it is such a pain to refuel I'm not to motivated to rebuild it right now. I wish there was some kind of micro fueling valve out there.

That's crazy that you lost a rubber prop... but way aren't you using a small APC?
Old 03-01-2008, 09:19 PM
  #74  
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Default RE: TWIN FEVER !!!

Believe it or not, the best prop with our rules is the 5x3 Cox. The planes are too big and heavy to take advantage of smaller props.
Old 03-04-2008, 09:24 AM
  #75  
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Default RE: TWIN FEVER !!!

Fast N Final spackle/filler. Its super light....can be thinned, and I've never had it crack on a wing or fuse I've used it on. Now lets just hope Fast-n-Final won't be an accurate description of this things maiden!

ZZ.

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