Mefisto build (BLEJZYK)

[u2builder]

Thanks Wayne. I assume you don't expect them in the near future. , correct? If not, do you have an estimated time? Jarron recommended the CN 32mm motor mount which I purchased. Is the approach to cut off the glider nose such that the circumference is the same as the outer lip on the motor mount and can the nose then be deformed into the required round shape? Is the outer shell strong enough or does it need an interior wrap of fiberglass in the mount area? Would the cut be parallel to the rear of the canopy?

BTW you prefer clear gloss, semi gloss or matte Polycrylic? About how many thin coats? Do you sell any fiberglass cloth tape for reinforcing the center joint for a one piece wing? What epoxy do you recommend?

Thanks

 

[Konrad]

Ecal 2212 is that the can or stator, diameter length? I find that a prop that is a bit closer to square works better for these efficient gliders, like a 9x8 vs the 10x6.

Smith Industries 30 min epoxy is more than adequate and easy to get.

No need for any extra fuselage glass work. Yes, the fuse should be easy enough to change to a round cross section. 32mm looks to be a bit large for the fuse. Can you post a picture of the firewall and fuse?

I like to set my thrust line for 1.5° to 2° down thrust datum from the stab, and a bit of right thrust just to make sure there isn't any left thrust.

P.S.
I use a hardwood (plywood) block to span the center line break as my hard points for the hold down bolts. (The supplied blocks are just fine, You are trying to set things up so the bolt doesn't crush the foam). I use 2 bolts not the 4 shown.

 

[Konrad]

FYI;

I think Blejzyk has changed the configuration of the fuselage since I last saw a kit. Can you post a photo for what fuselage you actually have? Is it a 2 piece, with slip on nose? is it a 2 piece "canopy style" nose, or a one piece "canopy style" nose. I think each will require a different motor mount/ firewall set up.

 

[Wayne]

I can see if I can get some electric noses from Artur, might be a couple of weeks. In the mean time you would work on the other parts of the plane.

I have used the Semi-gloss Polycrylic in the past. Very easy to use. Just do thin coats, I like to do both sides at the same time. Fine sanding between coats. I can usually get 2 coats in one night as it usually dries quick. Sand the wood with some fine paper before the first coat. Then very little sanding between coats. Don't let the Polycrylic pool in the hinges, and clear out the hinges so they have smooth operation at each sanding. The more coats you do, the better it looks. It is a very satisfy work.

We do not sell fiberglass, but we do have some we can send to you for free with your next order, just include a note to remind us.

 

[u2builder]

The CN models 32 mm motor mount which I purchased is shown. The front of the tape on the white nose is circumference of the outer lip on the motor mount so that would be about where the nose would be cut if the white shell is strong enough.. If needs to be wrapped inside with a layer of fiberglass (probably, please comment) the cut line would be a little further back. The The 2212 980 kV outrunner has a 28 mm outside diameter. So there is not much clearance. The motor shown is that type but the shaft would be reversed. I would choose a different brand with more flexible wires. The motor would mount behind the firewall. The motor wires would have to exit below below the fuselage and then reenter behind the motor and be covered by a little protective shroud or the motor bell would rub on them. There are no smaller diameter motors I can find that are powerful enough AND light enough. In runners are too heavy.

What would be the width of the fiberglass bandage in the wing center. I'd like to use as little as required to do the job. I am a gentle glider pilot. Is 4 oz cloth sufficient?

Thanks!

 

[u2builder]

Thanks Wayne! I would definitely be willing to wait and have plenty to keep me busy. I would very much appreciate it if you could get the purpose made electric nose! Thanks.

 

[Wayne]

ok

 

[Konrad]

I have many 20mm inrunners that are infinitely more suitable for this application than an outrunner. But they do cost a lot more. So for sport use they might not be what you want.
with the down thrust and 4mm diameter (2mm clearance) you should be able to train the wires to clear the rotating can without needing to exit the fuselage. I think I give some details here. That slip on nose is going to be a problem with a motor. You might want to look at how we mounted motors way back in the old days of round cells. Are you thinking of taping on the slip on nose every time you change the battery?

 

[u2builder]

Wayne posted that he might be able to get me an electric nose from Artur and that is worth waiting for if it is available. It is a good way to slow myself down.

The electric nose has a canopy for access to the battery and if I had to use this glider nose it would be permanently mounted with the motor and I would need to cut in a canopy.

 

[Konrad]

Sorry, I ran out of my daily allotment of posts. In the mean time, I'm actually a bit surprised nobody has addressed this question. (Come on guys there has to be more than one way to skin a cat! Let's hear it).

While 4oz cloth will work fine I prefer 2oz cloth as it has more than adequate strength and is much easier to feather edge. Go back into this thread to see how I feather edge.

If weight is a major driver in your build I'd glass the bottom of the wing to span about 5mm past the wing seat. If for no other reason than to harden the wing against the fuselage. On the top I see no reason to go past the aileron/flap cut.

 

[u2builder]

Thanks Konrad! Good info.

 

[u2builder]

I am curious what type of wing I have on my Serafin and where to locate the wing on the footage. I am posting here because it is a more active thread!

The instructions note the following:
"FUSELAGE Wing position on top of the fuselage: - HN1033 profile: as per drawing - S6063 profile: move the wing forward by approximately the thickness of the leading edge"

I don't know which wing comes with the kit and there is no drawing for the Serafin at on the Bleizyk website. The Mefisto is said to be similar. I notice Konrad moved his wing forward 4-5 mm.

I think I read on some forum a post by Wayne that stated that a wing used for thermal has greater incidence than for slope. Since the Serafin is listed under Slope on Aloft site perhaps mine has the slope wing.....S6063???? which would seem to have the greater incidence via the instructions.

Anyway, I am interested in Thermal and would like to know where to mount the wing or what the incidence should be. Thanks

 

[Konrad]

There isn't a nickel's difference in the thermal mode/trim. But I think the box top should say what is the airfoil. Again decalage will have no impact on your thermal performance. But I did raise the LE of my stabilizer 0.7mm so as to remove any camber (down trim) I was carrying at my aft CG. This can all be trimmed for after your test flights.

So the short of it is move the wing forward until it is stable on the fuselage wing seat. And if you like the efficiency of a rearward CG raise the stab's LE a bit.

 

[u2builder]

Thanks Konrad. Th boxtop says HLG is all Handwritten in pencil is Serafin VF. But in any case I get the gist of your comments. I am such an unskilled glidr pilot it surely won't matter. Curiosity is all.


I am also curious how what the hinge material actually is. I can't really see it. Th machining is very impressive. I am not familiar with anything like this, just tape hinges, CA hinges, and various plastic hinges.

 

[Konrad]

I haven't torn mine (yet) but I think the live hinge is a polypropylene strip in between the balsa skin and foam core.

 

[u2builder]

I am working on a Serafin, but I think this is the more active thread.

My question is should I install the servos in the marked locations with the control horn nearest the leading edge or the trailing edge (I am going to do the standard down drive set up). I have seen the servos done both ways in various threads. Thanks.

 

[Konrad]

I assume you mean the servo output arm. I like to place these forward towards the LE. (This causes less angular errors in the pushrod at the cost of a longer push rod [flexable]) Do bias the surface control horns to maintain leverage and differential.

For the flap I like to place the control horn clevis hole aft of the surface hinge line for leverage when the flap is fully down. For the aileron I like to place the control horn clevis hole aft of the surface hinge to get some mechanical differential. Place the clevis as close to the servo output as practical (usually the first hole in the servo arm.

Note: Use a large enough flap servo arm to allow at least 20° up flap movement to be used as part of an articulated trailing edge and when coupling the flap movement as ailerons

 

[u2builder]

Thanks Konrad. Great to get answers with explanations, and I appreciate the answers to questions I didn't ask, but should have.

 

[Konrad]

You’re welcome.
Having built, designed & engineered myself into a corner a few times. I try to share my experiences so others don’t have to suffer the same fate!