beepee

I just today picked up a complete 1/4 scale Waco built from Pepino's plans, Its got a 90" W/S and I would estimate it weighs in at about 27# with a Quadra 50 in the nose. Unfortunately, I did not get the plans. Does anyone know what the CG location should be. The incidences? Control throws?

Would appreciate any help I can get.

Thanks,

Bedford

SilverEagleBW

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I have the plans in my archives here somewhere,,gimmie a day or so and i'll look that up for you.

beepee

Thanks SilverEagle. Did you build it? I would appreciate any comments you may have about flight and handling. Would lilke to discuss the possibility of buying a copy of the plans from you.

We are still in flying season around here, which runs from September 1 to August 15th, but the weather doesn't look too good for any test flying this weekend. Patience, patience.

Bedford

SilverEagleBW

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The CG is 1 9/16 in front of the leading edge of the bottom wing,,,,,,,,

beepee

Great! Thanks, SilverEagle.

Bedford

Big_Bird

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Bedford, do you happen to have any photos of your YMF-5 that you could post here? Did you fly it? What engine?

beepee

Hey, Ken, good to hear from you.

I have not done much with it since ... working on other projects. I have not flown it yet, but will soon. It has a Quadra 50 in the nose that I have not run, but feels like it has good compression.

I have to get some pictures sometime. I always do before first flight. Don't want to jinx it.

I saw you fly your B-J at Bomber. As usual, nicely done. Sorry I did not get over and say high. I think it was too hot to move!

Bedford

Big_Bird

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Looking forward to the photos Bedford.

I have ordered the plans and Craig at Fiberglass Specialties sent me these photos of the cowl and wheel pants. I plan to use a G-62.

I had a great time as usual at Bomber Field even though I lost my Corsair. The receiver died. Someone stole about half of the plaques so I didn't get mine at the awards ceremony. Nick Stratos said that they have been reordered.

Ken

beepee

I am thinking about a G62 as well. I will see how she does with the Q50 and then decide. Some of our Club members have G62s looking for an airframe to pull around. I don't think I will suffer a weight penalty as the plane was badly tail heavy when I got it (one of the causes for my delays). I have had to add at least a pound of nose weight to get it in line. A heavier engine would be nothing but a plus.

Will keep you posted.

Very sorry about your Corsair. Fortunately I missed the incident.

Bedford

Big_Bird

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The G-62 would be a very good engine for the plane. Also the Zenoah GT-80 would be a good choice. I would like to find one at a reasonable price.

Are you going to Austin on the 14 & 15 for the Hill Country Flyers big bird flyin? I plan to be there.

beepee

I should go to Austin, but I am trying to prepare for Space City's cross country event the following weekend. My daughter lives there and we don't get to see her near enough.

I have a great source for YMF-5 3 view that I will send you on Monday ... I have it in my office.

Bedford

SuperCub Man

Bedford - I am building one of those beautiful Wacos from Pepinos plans. He includes an awful lot of spruce in the fuse. Anyone find this a little over-kill or does it require this for the Quadras and Zenoahs. Could it be lightened by using more balsa? My buddies here urge me to build for flying - not crashing! I'd like to use a Quadra 52 with CH Ignition I have on the shelf, so it needs to be kept light!

James

Big_Bird

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I have a good friend who built the Pepino YMF-5 back in the late 1980s but never finished it. While I was over at his house a few days ago he dug it out of his attic. The fuselage without tail feathers or landing gear weighed 4.5 pounds. It was built with all spruce per the plan call out for a plane with a greater than 1.8 cu-in engine. It was hard to believe how heavy it was. I believe you could grasp it by the tail and use it for a soft ball bat. I think by substituting medium balsa for the spruce you could save at least 2 pounds if not more. That's what I'm going to do and I plan to use a Zenoah G-62. There are so many cross braces and gussets that the plane will be very strong without all of the spruce. I do plan to use spruce in the wings as called for.

At this point I have all of the ribs built and all of the metal wing pieces built. I have done a lot of modification to the plans to correct obvious errors. The plans call for the bottom wing incidence to be 0 degrees, the top wing to be +2 degrees and the stab to be +2 degrees. The only one of these numbers that I disagree with is the top wing incidence. I think it should be -1 degree. That's the way I am doing mine unless I get my mind changed. Another friend built 3 of these planes. The first one had +2 degrees on the top wing and it flew terrible until he took the 2 degrees out. It took off like a home sick angle and any time you changed engine RPM the pitch changed drastically.

These plans are pretty poor in several respects. For instance, look at the top wing drawing on the fuselage side view sheet. See how the trailing edge of the wing center section curves up. Now look at the rib for the top center section. It curves down. The bottom wing on the fuselage side view does not match at all the actual wing shape. I'm enclosing a couple of photos to show you what I mean.

Note: for the lower wing to fit up into the fuselage, a considerable amount of wood will have to be cut out of the lower 3/8" x 3/8" crutch member. This means that an additional 3/8" x 3/8" piece needs to be glued above the this long 3/8" x 3/8"piece. The 3 views show that stringers run from the landing gear to the tail. If built by the plans the lower wing will hang somewhat below the fuselage saddle and can not be streamlined into the fuselage.

If you start comparing a rib drawing in one place it does not begin to fit the same rib in another place. Drafting precision was not one of Jim's strong suits.

SuperCub Man

Hi Big Bird - Well I guess it pays to research a plan set before starting to build off them! I really appreciate the tips you have listed here. You mention that you have cut all the ribs. I presume you used the "Basic Rib" planform that he shows on sheet 3. I presume then that you would have used this to modify the length of the center ribs.
I agree that the top wing should be at -1 degree. My 26% Skybolt - plans by Dario Brisighella - was incorrectly drawn but I set it at the same incidence as the lower wing and it flies OK. But I wish I had set it at a negative 1 degree as I think it would help with some of the "strange things" it does some times! Too hard to change now. However, as a point of interest - I have read that the wings on a number of bi-planes are set at different incidences so that only one wing stalls at a time. I wonder if it matters if it is the top wing or the bottom wing and if Pepino was setting up the top wing to stall first? (Just thinking!)
My 1/4 scale Super Cub is from a Balsa USA J3Cub kit that I bashed into the Super version. It's mostly all balsa fuse framing. I used 1/64 ply gussets all over the place aft of the wing and it has held up to many landing errors and lots of water flying. It has a Quadra 41 in it so it has to take lots of shaking as well. I read in a thread somewhere where someone was building the Pica YMF-5 and they said they were glad all the stringers were spruce so you couldn't put a finger through one when picking up the plane. I thought that they must be very "ham handed"! I think hard balsa would suffice.
I did notice that the bottom wing fairing was not on the plans but I missed how it should fair back into the fuse aft of the wing root and now I see that it couldn't the way he's drawn it. Also I don't like the wing bolt going in at the angle illustrated.
I think a lot of these things can be cleaned to make this a great model. We'll just have to double check the drawing accuracy before cutting.
I'm not starting mine until into the new year but I will be making lots of notes on the plans as my buddy is also going to build one with me, so we'll be twins! The heads up you've given me will save us lots a grief. I'd appreceiate any updates you find as you progress. Are you planning to do a build here?

Big_Bird

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Hi Big Bird - Well I guess it pays to research a plan set before starting to build off them! I really appreciate the tips you have listed here. You mention that you have cut all the ribs. I presume you used the "Basic Rib" planform that he shows on sheet 3. I presume then that you would have used this to modify the length of the center ribs.
Yes, I used the basic rib pattern for shape. What I modified was the placement of the slots for the spars so that they would fit the wing spar spacing shown on the wing plans.
I agree that the top wing should be at -1 degree. My 26% Skybolt - plans by Dario Brisighella - was incorrectly drawn but I set it at the same incidence as the lower wing and it flies OK. But I wish I had set it at a negative 1 degree as I think it would help with some of the "strange things" it does some times! Too hard to change now. However, as a point of interest - I have read that the wings on a number of bi-planes are set at different incidences so that only one wing stalls at a time. I wonder if it matters if it is the top wing or the bottom wing and if Pepino was setting up the top wing to stall first? (Just thinking!)
Several years ago I built Great Planes Giant Aeromaster. I set up the wings as called for on the plans, 0 degrees on both wings. The plane flew good but was a little pitch sensitive. I raised the trailing edge slightly to give the upper wing -1 degree of incidence. Of course that meant adjusting the inter plane struts. The plane then grooved beautifully with no pitch sensitivity. If you can imagine with the wings set this way it is a little like the front wheels of a car having a little toe in. The theory behind having the top wing stall first was that the plane would then pitch down taking the wing out of the stall condition. Most of us don't fly our R/C planes so slow with such a high angle of attack that this would ever be of benefit.
My 1/4 scale Super Cub is from a Balsa USA J3Cub kit that I bashed into the Super version. It's mostly all balsa fuse framing. I used 1/64 ply gussets all over the place aft of the wing and it has held up to many landing errors and lots of water flying. It has a Quadra 41 in it so it has to take lots of shaking as well. I read in a thread somewhere where someone was building the Pica YMF-5 and they said they were glad all the stringers were spruce so you couldn't put a finger through one when picking up the plane. I thought that they must be very "ham handed"! I think hard balsa would suffice.
I have a Dumas electric Waco YMF-5 and I lost track of the number of times I cracked the 1/16" square stringers. On the other hand, the stringers on the big waco are 1/8" x 3/8" and placed on edge. You would probably have to be someone who drug his knuckles on the ground when he walked to regularly break these balsa stringers.I did notice that the bottom wing fairing was not on the plans but I missed how it should fair back into the fuse aft of the wing root and now I see that it couldn't the way he's drawn it. Also I don't like the wing bolt going in at the angle illustrated.
We will have to put a plywood piece in the trailing part of the wing for the bolts to go through and the head of the nylon bolt should fit squarely against this plywood. Of course Jim doesn't show this plywood. I also don't like the way he shows the leading edge of the wing wedging in above the block. The leading edge of mine will get two more nylon bolts.
I think a lot of these things can be cleaned to make this a great model. We'll just have to double check the drawing accuracy before cutting. AMEN, check, check, and re-check.I'm not starting mine until into the new year but I will be making lots of notes on the plans as my buddy is also going to build one with me, so we'll be twins! The heads up you've given me will save us lots a grief. I'd appreciate any updates you find as you progress. Are you planning to do a build here? Probably when I start gluing.
I don't plan to start gluing until all of the parts have been built and these odd items have been corrected. I'm going to build the wings solid so that they don't plug in. I'm putting all of the hardware in so that I can use flying wires if I want to.

SuperCub Man

Thanks for that Ken. I agree with all you've said. On looking at the plans I notice there is no fuse doubler. Most aircraft I have use a 1/8 ply or 1/8 lightply doubler from the firewal back to just aft of the wing saddle to strengthen. I think he has used so much spruce he didn't feel the need for this. I am tempted to make one of 1/8th ply and use spruce (basswood) just around the firewall and back to the diagonal over the wing saddle. It would be notched so the cross members seat in it and also I'd use the 1/64th ply half round gussets to support the other members. Then everything aft of this would be medium balsa with 1/64 ply gussets. It would make a nice strong box! I've noticed on some ARF's that they run a portion of the doubler through the firewall for extra firewall support. The portion of the doubler on the engine side of the firewall is then secured with a piece of tri-stock on each side. I like this idea. Not sure about the four main longerons and may keep them as basswood. Still don't know about one piece wings. The bottom wing would have dowels at the front and just the two nylon bolts as indicated, but with the addition of the ply strip as you mentioned. I don't want to get into too much re-engineering and having the cabanes semi-permently fixed would be nice. Will think further on that. I have a Caravan and my Skybolt wings are 80+inches so no problem on size.

Big_Bird

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A few posts above, I mentioned that a good friend started a Pepino Waco a few years ago but didn't finish it. His work on it was first class. I asked if I could borrow it to look at. He brought it to me at the club meeting tonight and told me that when he transfered it to my truck that he never wanted it back. Sooooooo here it is. If all works out I plan to go over to Lone Star Balsa tomorrow and buy my balsa, bass wood, and plywood. What do you guys think of substituting bass wood for sitka spruce in the spars? I've never used spruce in my giant scale planes and have never had a problem with bass wood.

Oh yes, here is same good friends scratch built 1/2 scale Spacewalker II.

SuperCub Man

Are you going to try to re-build that fuse or just use it as a building guide? I found a number of the top builders are using basswood as it is lighter than spruce. It is considered a "soft" hardwood. Combined with the judicious use of lite-ply, I think you can save a lot of weight. Interested in what some of the other builders in this forum think!
Buy it from the lumber yard and strip it yourself - cheap!

Big_Bird

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No, I won't use the old fuselage because I think I can build one at least 2 pounds lighter. I just plan to look at it.

As it turns out sitka spruce is pretty hard to find in the metroplex. Lone Star Balsa only carries bass wood which will suit my purpose just fine.

Big_Bird

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If you cut the stringer notches for the lower rear formers as shown on the plans, here is what you get. The best way is to not cut the notches until the bottom formers are in place. Then use a tight line to find the proper location of the stringers.

There is no way that this plane needs all of that cross bracing. The fuselage can be built with balsa cross bracing in place. After all of the stringers are in place most of the cross bracing can be removed. The stringers add a lot of strength to the structure. This plane is strictly 1980s design and I would like to think that we have learned a lot about strength verses weight since then.

SuperCub Man

THAT is a GREAT tip. It's not something I'd have caught until too late!! Thanks for that. I'll add these notes to my plans to keep track of them.

Jim

Big_Bird

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You have heard of getting the cart before the horse, well, this is getting the horse before the cart. In the past I have always built the plane and then struggled with getting the cowl properly located and attached to the firewall. This time I started with the firewall while it could still be put down flat on the table.
A very good friend of mine (RCU screen name Gremlin Castle) did a very skillful job of turning my firewall assembly on his lathe. The actual firewall (F2) is 1/2" plywood with a spacer block that provides 2 degrees of right thrust. Of course, the spacer is offset to the left the correct amount so that the prop comes out in the center of the cowl.
Photo 1 shows the cowl in place with the holes cut for the muffler and spark plug lead.
Photo 2 shows the recessed T nuts for the cowl mounting tabs. They are recessed because some of the framework will glue over these T nuts. The firewall is 1/8" smaller in diameter than the curved balsa front. This is to allow the 1/8" balsa fuselage sheeting to be glued to the edge of the firewall for greater strength.
Photo 3 shows the mounting tabs. 1/8" x 1/2" hardware store aluminum.
Photo 4 shows the engine offset.
Photo 6 shows the large hole in the firewall. I put the hole there to allow me to fish out the fuel line for the engine and put it through the firewall.
Note: Look for the photo number reference in the bottom right corner of the photo.

SuperCub Man

Great idea Ken. Thanks for that. Doing all that firewall work before assembly will certainly simplify the build. I always get ahead of myself and forget unless construction notes are made or supplied! Similarly, making hinge holes with leading and trailing edges of stab and elevator and ailerons and wing is another note I must make for myself! Much easier lining things up. Keep it coming!!

Jim

SuperCub Man

Hi Big Bird - Any advancement on building the Pepino Waco? Very curious about how you're making out. My shop is too cold to do much work at present, but ocasionally I'll fire up the electric heater, burn a few dollars of electricity and get it warm enough to take off the gloves and look around! Looking forward to a little warmer weather so I can finish the Rapide and start the Waco!

Big_Bird

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A lot of other things have taken priority lately but I think I'll be getting back on the Waco pretty soon. I have managed to get a few flights in on my other gassers as time permitted.