Posts: 1703
Joined: 5/27/2003 From: Orangeville,
ON, CANADA Status: online
quote:
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..
Posts: 9824
Joined: 11/22/2003 From: arlington,
WA, USA Status: online
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.
Posts: 147
Joined: 11/20/2002 From: Evansville,
IN, USA Status: offline
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.
Posts: 9824
Joined: 11/22/2003 From: arlington,
WA, USA Status: online
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.
< Message edited by combatpigg -- 2/28/2008 5:08:42 AM >
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Joined: 10/14/2004 From: San Antonio,
TX, USA Status: offline
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?
< Message edited by KidEpoxy -- 2/28/2008 6:35:55 AM >
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Optional MA is part of AMA history, we can go optional AGAIN if we just say so
Posts: 9824
Joined: 11/22/2003 From: arlington,
WA, USA Status: online
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 ? 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?
Posts: 9824
Joined: 11/22/2003 From: arlington,
WA, USA Status: online
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!
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.
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the "other" andrew I'm not older than dirt, but I can remember when it was patent pending
Posts: 1830
Joined: 2/10/2002 From: Just a little south of Raleigh,
NC, USA Status: offline
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.
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RE: TWIN FEVER !!! - 
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