Pirat 1.5m slope (Blejzyk)

[Konrad]

Hank,
I'm glad your kit looks to be a later kit.

Please feel free to add your thought to this thread as you build yours.

As I don't see a drawing, it looks like it is up to us to engineer a wheel mount and elevator actuation system.

All the best,
Konrad

 

[Hank GB Z]

Hey Konrad,

Yeah for the elevator I’m planning on putting the servo in the rudder avoid all that slip and friction from a long run of the push rod. For the wheel I’m thinking ply blocks epoxied in place with an axel between them.

Reading through the stuff you posted previously the height for the polyhedral is for just Rd elev I’m thinks something like 3 degrees a side based on pictures of the full size ones.

Hank

 

[Konrad]

As this is a high wing there is no need to add any dihedral for an aileron ship, as the fuselage will aid the turn in a rudder commanded yaw. But 3° measured on the bottom of the wing should look good. The outer wing thickness tapers about 2.5mm (0.100")

 

[Konrad]

Well I had some left over epoxy. So I started the build! Using the TLAR I raised the wing tips 16mm. This works out to be about 2.5°. I might be on the shy side as the ailerons are a bit small. (Note the drawing is showing 62mm! )

I will be using 2 aileron servos near the aileron. This is to allow for differential adjustment and allow the ailerons to act as spoilerons when landing.

I'm telling myself that real pilots work both the rudder and ailerons to control their sailplanes.

 

[Hank GB Z]

Konrad,

Did you block sand the outter panels to get the angle?

Hank

 

[Konrad]

Yes. In fact my panels would have presented anhedral if I didn't.

Looking at some photos of the full size, it looks like this kit has an oversized rudder. I need to look into narrowing the chord at the top of the rudder about 10mm. As my Pirat is set up to rely on the ailerons as the primary directional control I don't think a smaller rudder will be a problem.

 

[Konrad]

I’ve been building toy airplanes since the late 60’s, OK 1969. With the Blejzyk kit I just learned a new to me process. With thin veneer wood sheeting Blejzyk has you under cut the veneer by crushing the foam for a few millimeters as shown on the top wing panel. What this allows is the formation of an epoxy bead under the veneer that spans the joint. This makes for a much stronger joint! If making a face (butt) joint with the wing prepped like the bottom panel there would be little glue actually bonding the panels together. (Note; any glue on the white styrofoam adds NO strength to the joint). After the joint cures a follow up fiberglass bandage will be applied on top of the veneer. This wing is of a stress skin design, there are no spars. So all skin joints need to be well fitted and have some fiber running across the joints. Here Blejzyk is using fiberglass. I’ve seen some guys omit this glass as it interferes with the staining of the wood. DO NOT OMIT THIS FIBERGLASS!

Now that I can hold the 1.5meter wing in my hand, I’m thinking that maybe lifting the wing tip 18mm to 20mm might actually look better than the 16mm I lifted the wing tip.

With a bright light shinning through the wing I see that there are factory installed hard points for the hold down screws. The center of these blocks are 25mm and 95mm from the training edge.

Here are some spec’s I didn’t see on the sales page, these are my measurements.
Aspect Ratio about 13:1
Wing Area (non FAI) 17.3 DM2, (265 square inches)

All the best,
Konrad

 

[Hank GB Z]

Konrad.

Thanks for the notes. My kit would have annhedral too if just glued as is. I read that note about crushing the foam. Sounds like a good technique.

Hank

 

[Konrad]

As mentioned earlier the rudder is too wide at the top. I'll have to cut down the rudder cord about 10mm to match the stabilizer cord. With this photo I'm also trying to show that the rudder is a hollow core balsa structure.

I hope this, oversized rudder, was done because it would have been difficult to bring the sides together any faster without splitting the side sheeting. I hope the larger rudder wasn't to address a stability problem with a more scale rudder.

All the best,
Konrad

P.S.
Early SZD 30 had the wide cord rudder later SZD 30 had the narrower cord rudder. I'm staying with the earlier wide cord rudder.

 

[Konrad]

Well this is going to be the first of what I'm sure will be a couple of retractions. I've learned that there has been an airworthy notice issued for the SZD 30 that resulted in the narrow rudder cord to minimize the torque on the fuselage. Early Pirat SZD30 had the wide cord and that later and reworked SZD 30's had the narrower rudder.

So to keep the rudder response as strong as possible on my model I'm going to stay with the as delivered rudder (wide cord).

 

[Wayne]

Both options will look good. Atrur said he would get some pictures of the wheel installs as it would be better than writing it out, especially when going through a language translation. Will probably have them in a day or two.

 

[Wayne]

Heard back from Artur, here is what he says and shows:

the Pirat circle can be mounted in many ways - it is probably the fastest and the simplest one.
It uses clippings for this - pusher waste , mats the laminate inside the fuselage , I cut the piece of the pusher and match it ,two drops of cyanoacryl to pre-hold, 5 minute resin and two pieces of glass fabric - you have to do it quickly .
That's it, all the work.

best regards,
Artur

I like it it. Simple, yet functional.

 

[Konrad]

Thanks for the posting.
Artur has never seen my landings! I'll need to spread my landing forces over more area. Also the 3 views show the axle outside the body line.

 

[Wayne]

Since he is using plastic he has some give. It is called elegant and simple. LOL It is a pretty darn light plane too.

 

[Konrad]

This will be another of my 2020 Sunset Beach hopefuls. I had sized and shaped the hold down blocks a while ago. But from my experience with other light Blejzyk fuselages I didn’t want to cut into the top of the fuselage under the wing if at all possible. This meant that I’d need to use threaded fasteners as I didn’t have clamps with deep enough throats to reach the aft hold down block. Drilling and threading the block meant that I would have to align the wing to the fuselage and the blocks to the fuselage prior to drilling and tapping. The more things one needs to align, the more chances thing will slip out of alignment. So to give myself some leeway I used rather small diameter bolts. This meant that if things are not perfect I can move the holes a bit and step up to some larger fastener. If nothing moves and the fuselage to wing are square all I need to do is ream the holes in location and go up to the appropriate fastener size.

All the best,
Konrad

 

[Hank GB Z]

Hey Konrad,

I’ll join you in trying to get mine done for the SunSet fly in 2020. It’s my birthday weekend so I’ve got approval to attend just need to book my camp site and get building. I probably won’t start my Pirat till Christmas time though.

Are you planning on putting the elevator servo in the vertical stab? I dont like tube with two bends so that’s my current plan.

Hank

 

[Konrad]

Sunset Beach is just inside my driving range. As I value my sleep (I don't sleep well at camp sites) I drive in each day from San Francisco. I don't know if there are camp site lefts.

Sunset State Beach Camp N Fly May 2-3 2020 :)

Join us for one of the most popular social flying events in California! A great weekend of flying, fun, raffle and a fantastic Saturday night potluck BBQ!! Get your Campsites now for May next year, otherwise they will be gone very soon! Any campsite will work great, the closest ones are sites...

forum.alofthobbies.com

While I like the snakes (Bowden tubes) supplied by Beljzyk I too have concerns with having to make such sharp bends to reach the top mounted elevator. So I too will be placing the servo high in the vertical fin. I'm sure there will be a weight penelty with the servo being aft. But I'm sure the improvement in control responce will be worth it. Since I'll be routing wires back there I'm thinking I might as well place the rudder servo in the fin. I'll need to look into this a bit more carefully.

For servos I'm using 4 of these KS HD47 MG running on 2 LiFe cells. I do like these sub 6 gram servo for this type of ship.

KS HD47MG Servo - 1.2Kg (16.66 oz in), .10/sec - High Voltage

High voltage (4.8 to 7.4V) digital servo with a coreless motor and tiny weight with reliable metal gears and good specs makes this a very nice servo that could sell for a lot higher price at some other store.

alofthobbies.com

All the best,
Konrad

 

[Konrad]

These might be a good servo with FrSky's S-Bus RX's. I wonder if the savings in wire weight (even if using the common bus bar architecture) will make up for the added weight of the servo. The only hit I see is that these are standard 4.8v and have plastic gears. (Sure looks like they are GWS servos, I wonder if the mechanics are GWS. Notice the Corona label on top of the assembly strap).

Corona SB6033 Servo - .95 kg (13.19 oz-in), 0.10 sec - 6.2g

Corona SB6033 Servo This is a S-bus servo and is programmable using (..........). This servo also works as a standard PPM servo too.

alofthobbies.com

 

[Hank GB Z]

Hey Konrad,


I'm starting to work on my Pirat. For gluing the blocks for the wing bolts to the fuse. Did you use the two small pieces supplied in the kit or did you replace them with one long piece? I would think gluing one long piece in using both the bolts and a clamp like you would be easier than two small ones. Did you use the brass insert nuts that came with the kit or a more common T nut. My brass nuts are tight on the screws which is good gives good locking features.

I'll try to post some pictures soon.


Hank

 

[Hank GB Z]

Ok well here are some pics of my progress. I have cut out the area for one aileron servo. I’m planning to do the other one soon. I’m doing this before I glue the panels together.

I also started working on installing the elevator servo in the vertical stab. More on this later.

The horizontal stab is installed. I still didn’t get the orientation perfect so I will adjust the stab it’s self instead of redoing the tapped holes.

Next week I will try to install the wheel and the rudder servo and boden tube.

Hank