SydDythers

My Feedback: (5)

Well, I've got tired of waiting for a Yak 54 of Extreme Flight quality. I already have a 50CC EF Yak and love it but there is quite a bit of mileage on it. I really don't want to pay $650 or whatever it is for another or from Quique. So with winter and snow just around the corner, I've decided to make some plans of my own and use ideas from my Yak and my BME Edge V.2

I have some experience in Metasequoia making models for Aerofly but Autocad is proving to be a different beast altogether! The learning curve is steep but I've managed to master the basics in 4 nights. Today I started creating the plans by tracing a 3View. The fuse is relatively round so extrapolating from the 3 views shouldn't be terribly difficult. I realize that the photo of my progress tonight is pretty rudimentary but I am getting the basic shape down first before I build it up. Basically the plan is to build the model virtually to get the formers and such and then tear it down to print out the parts.

Not sure if anyone will be interested in my progress but I figure it'll take a couple weeks to CAD it out. I guess I'm posting this to show that a noobie can tackle this kinda stuff and be successful (hopefully!). If this works out I hope to scale it to the 75CC or 100CC class.

Cheers,

John

DT56

My Feedback: (18)

I'm very interested! Just spent an hour on RCU and the net looking for plans for that size Yak 54. Seems to be plenty of interest in flying the Yak, not so much in building one.

I started design on a slightly smaller, profile version this past spring, but have yet to build it. I'm not interested in exact scale, so I might just add some formers and stringers to the profile for a full fuselage. Building half a fuselage at a time on top of a profile crutch like some freeflight models, is an accurate and easy method of construction. With a larger aircraft, you could build both halves side by side and then assemble them, without a significant weight penalty.

Even thought about modifying an OMP 79" yak in the same manner, but decided I wanted a longer tail moment.

Good luck with your plan!!!

DT56

SydDythers

My Feedback: (5)

Thanks DT,

Made very good progress even after that last shot I posted. I'm not terribly interested in keeping it 100% scale so I'll be fudging here and there. Most important will be getting the airfoil right and I will have to get profili or something similar...great...one more thing to learn!

DT56

My Feedback: (18)

Syd,

I've got Compufoil and would offer to handle the airfoil problem, but the computer it's installed on is out of service. If I can resolve the problems with it before you complete your design, I'd be glad to help.

I've only seen photos of the 54 wing, but it appears to be the same airfoil from root to tip, just scaled for size at different stations. If you have an existing wing to copy, you could make templates of each rib station and use those on the new wing. With CA glue and a few sticks, making templates is no longer a great problem.

DT56

Brent G

My Feedback: (5)

Syd

I am also working on a yak design. I am building a 120 size for a new mvvs 26 that I just purchased. This will be the 4th plane I have designed. If I like how it flies I am planing on scaling it for 50cc and 100cc. I am looking for an all up weight around 10 lbs. I am using compufoil and model cad for designing the plane. I will post my progress as I get started.
Here is a picture of my most recent design and the 3d rendering of my yak wing.


Brent

SydDythers

My Feedback: (5)

DT, Thanks for the offer. I may take you up on that but for now I am focusing my energy on the fuselage. As I mentioned before, I have an EF Yak 54 87" and will probably borrow some ideas from it, including the airfoil.

Brent, nice job on your build! I'll be interested to hear the flight report. Good luck on your yak project...is that mvvs gas or glow? I am going to try and design this airplane extremely light and hopefuly I'll be able to beat my EF Yak by 1/2 lbs or so which would put it around 14 3/4 lbs with a DA50 on the nose!

Here is where I am currently...just getting the shape of the fuse, cowl and canopy out of the way before I start building up the formers.

Cheers,

John

Brent G

My Feedback: (5)

John

I now have about 80 flights on that plane. The plane flies great with a saito 100 at 8.25 lbs all up. I am taking some of design features of that plane and I am incorporating them into the yak. The other plane is my new scratch built Edge 540 with a DA50. It is a copy of an AeroWorks Edge. I made some changes like adding 200 sq!QUOT! of wing. 20% larger air-foiled stab and elevator. I moved the stabilizer down to the thrust line trying to improve the knife edge coupling. That worked great, knife edge flight is almost rudder only with no mixing.

The engine is the mvvs 26 gas. I will be running it with the tuned pipe made for that engine. Before I can get started on the yak I need the engine and pipe so I can design the tunnel.
Are you making your own cowl. I haven't decided if I will make a plug and mold like I have done for my other builds. I may just buy a QQ yak cowl for $40 and save a lot of work.

The Yak will have the things I liked about my most recent projects as well as some other new things I want to try.

Brent

SydDythers

My Feedback: (5)

Wow great work Brent...hope mine turns out as nice as those. I intend to make my own cowl. In the pics I posted you can see the purple discs where the cowl will be. I plan to transfer those disks onto cardstock and sandwich them between 1" insulation foam. Thus I'll probably have 7 or 8 of them all stacked up. Then I can rough cut the foam around the edges of the cardstock and then sand to a smooth contoured finish. That will give me a male plug. I may just use the male plug and fibergalss it then vaccum shrink it or I may make a female version to go along with it.

Cheers,

John

Brent G

My Feedback: (5)

If I end up making my cowl I was planing on stacking high density foam circles to get the needed length. Then I was going to turn it down on a lath to get the diameter and the radius on the front edge. From there the normal procedure. Glass it, fill and prime for what seems a life time. Make the parting board, polish, wax, pva, epoxy & micro balloons and voila I have a mold. Sounds so easy I just can't wait to make annother.

SydDythers

My Feedback: (5)

Ok, made some progress albeit somewhat limited. I've cleaned up the cad file so that everything is in perfect alignment. I want to jig build this so it is crucial that everything is as close to centered as possible right from the get go. I lengthened the fuse somewhat from the previous pictures. I wanted to get close to a 1:1 geometery between the wings and fuse and it was something like 1.3 to 1 based on the scale version. It's now down to about 1.1 to 1.

As it is now, the wingspan will be 86 inches and have a total wing area of around 1550 Sq In (including belly of fuse). The fuselage will be 78 inches. I may need to lengthen it a bit further though to prevent a nose heavy situation. To compare, the EF yak has an 87" wing and 85" fuse with wing area at 1450 Sq In.

This picture shows that I will have round and elliptical formers that wrap around a "box" structure which serves as the main support structure for the engine box and landing gear. This is pretty much what the EF yak does too.

Cheers,

John

Brent G

My Feedback: (5)

Where are you planning on positioning the wing and stabilizer in relation to the engines thrust line?

Brent

SydDythers

My Feedback: (5)

I plan to have 0 incidence and the wings and elevators will be in line with eachother and the thrust line. I also plan to make the stabs removable so I may experiment and add two stab tube holes...one in line with the wing and one 1/2" above it.

What do you guys think abot a NACA 0013 airfoil?

Cheers,

John

Brent G

My Feedback: (5)

That sounds like a cool idea. I am planning on placing the elevator on the thrust line with the wing slightly above mabey 1/2 inch. That combo on my edge works great. The Naca 0013 is very similar to the one I have been using. The only diference is I have thickened the wing at the tip.

Boogie

You'd better try an Eppler 169. Mike McConville says that it would probably be the best for a 3D plane. I am looking forward to this plane - I love yak 54s.

SydDythers

My Feedback: (5)

Would that airfoil's specs be Max Thickness of 14.40% at 26.5% of the Chord with 0 Camber?

Cheers,

John

Boogie

Yes.

SydDythers

My Feedback: (5)

Thanks for confirming.

Here's the latest progress...

SydDythers

My Feedback: (5)

Moving along...I've got the 3D outline of the fuselage pretty much set. As you might be able to see, I am now adding stringers. I will cull most of the purple discs...they are just placeholders for now.

Autocad is proving to be a major pain in the behind for 3D modelling...not very user friendly imho. Does anyone know how to grab the end of one object and move it around without moving the other end of it. This would be helpful in stringer placement. Basically, I can get a 3D box (stringer) anchored on one end but I'd like to be able to move the other end (4 points) into position rather than having to move each point at a time.

Cheers,

John

SydDythers

My Feedback: (5)

Ok some more progress...

I will probably make the canopy out of fiberglass as well so the top semi circles will be cut out and glued between 1 inch pieces of sandable foam core. I'll then glass over this mold. The green discs at the front will be utilized in the same manner to form the cowl...not sure how to do the louvers though.

I've got the basic box structure down (green and blue) and will begin the lightening process by cutting away a significant amount of material. This will also be an interlocking structure with the formers.

I aborted the stringer construction shown in my last post as I didn't feel it was exacting enough. I have come up with a different solution which I'll try once I have all the formers in place. I've probably got at least 3 days of major work left on the fuse before I am happy with it.


Cheers,

John

SydDythers

My Feedback: (5)

Not much progress but I've got all the formers set. Also mocked up an admitedly cheesy DA50 to bolt onto the firewall. It may not look that great but it's dimensions are very accurate. Just wanted to ensure the real thing will line up with the front of the cowl. It's ready for trimming now and I'll have a nice interlocking structure soon. Stay tuned...

Anyone actually interested in me continuing to post updates or you guys just want to see it when it's done?

Cheers,

John

Brent G

My Feedback: (5)

I am interested. I just received my mvvs 26 gas. Now I can start working on my Yak. Very nice little engine.

SydDythers

My Feedback: (5)

More progress...albeit somewhat limited. I managed to cut out the interlocking parts between the firewall and front of the inner box structure. I mocked up a 16 oz dubro fuel tank. Added an aluminum reinforcement bracket (green) and put in some drill holes to secure to the side of the box and some reinforcement ply and the bottom of the landing gear (not shown). These are just pics of the airframe split down the middle for better detail. I only work on one side and then use the mirror command to create the other half.

I still haven't started the lightening process just yet but am getting really close.

Cheers,

John

Brent G

My Feedback: (5)

John

What version of CAD are you using. I have been using model cad for my planes. I would like to use something with 3d capability, but the cost can be very high. For $75 the model cad has worked well, can't complain.

Brent

SydDythers

My Feedback: (5)

Brent

I'm using Autocad 2006 and it was a bit of a bear getting used to the 3D mode but I've got it mostly mastered after about 40 hrs or so of work on this project. I'm still learning bits hear and there. It is definitely not the most intuitive program out there but the way it is set up, once you figure things out, it's faster than other programs at getting things done.

Here are a few pics of my progress. Finally carved out and lightened the upper and lower part of the box and have started on the formers.

Cheers,

John

Brent G

My Feedback: (5)

John

Are you going to go with foam cheeks on the sides of the fuse like the extreme flight?
Or are you going with stringers and sheeting?

Brent