AJ Laser 230z 73" Build Thread

[Steve_JR]

Hey guys,

I'm currently building a 73" competition-scheme AJ Laser as well. It had been mentioned in a prior post that not many people install a canister or pipe on this model and I can see why. I was forced to knock the back out of the tunnel and extend it to the adjacent bulkhead in order for it to fit. I am keeping the bottom of the cowl closed and have an opening at the back for the air/exhaust to vent. If my fluid dynamics calculations work out, all the entering air at the front should be sucked out the back properly.

I'm about half-way through the build now so if screws appear missing or certain items aren't plugged in... there's a reason

My setup:

DLE 35RA
Mejzlik 20 x 8 Carbon Prop
Tru-Turn 3" Spinner
Fourtitude 12oz V2 Tank
PlaneBender Pro-Flow Header (1 & 3/4" drop) and Small Canister
Futaba BLS 175sv's Control Surfaces
Futaba S3073HV Throttle & Choke Servos
Vbar Control/Neo
Tech-Aero Super IBEC
OptiPower 3500mah RX Pack

Let me know if you have any questions about the header/canister stuff...

 

[Bipenut53]

First off, welcome to the site [MENTION=4415]Steve_JR[/MENTION] you will find this a friendly, helpful site. I notice you are using VBar control... So does that mean you are using the VBar transmitter along with the Neo? I didn't know there was an airplane mode in that gyro set up, I have only seen VControl in helis interesting. And second are you planning on putting a lip in front of the exhaust exit to assist in sucking the air through the tunnel?

Looks like a nice build and I'm sure we all would love to see some more pictures!

 

[Steve_JR]

Thanks for welcoming me!

No lip is planned for now. I will keep a close watch of the engine temps and adjust as necessary. I attached a video of Vplane software so you can see. I'll do a formal build once I have everything all done and tested

[video=youtube;sl6E6CNncbI]https://www.youtube.com/watch?v=sl6E6CNncbI[/video]

 

[Bipenut53]

Very interesting Steve, I will be keeping an eye on your build and testing process. I know VControl is a big deal in the heli side. So if VPlane follows along the same route, means you have full control of all adjustments from the transmitter and no need for a laptop at the field....

 

[AKNick]

[MENTION=4415]Steve_JR[/MENTION] I've been thinking about using the 12oz tank as well. I do remember my 35RA sucking quite a bit of fuel during break in, so I'm probably going to stick with the 16oz tank until after break-in and use the 12oz after the 4th gallon or so maybe.
What did you use on the firewall? Is it fuel proof and does it have a hard finish? thanks.
When you say you are not opening up the front of the cowling, are you going to baffle the inlet air from the cooling ears to somehow run over the engine cooling fins? I would think it would be better to block off the ears, and open it up in front of the engine, keeping in mind hot air does rise... so when ground running you'll need a way for that air to escape the cowling even though the flow calculations work... maybe adding a louver or two on the side to help relieve trapped hot air and the possibility of a pressurized cowl in flight? Just a few things to think about.
Thanks for sharing!!!

 

[Steve_JR]

I haven't cut the cowl yet, but if you go to SupaTim's build thread, I will be opening the main air inlet (in front of the cylinder head) to the same size/shape as he did. I'm not going to add any baffling yet. My theory is that (even at idle on the ground) air is constantly being forced into all 3 inlets. This creates a positive pressure in the engine bay with the only escape being out the back of the tunnel. I'm not a huge fan of having multiple openings in the bottom of the plane because this can create different areas of pressure and a "swirling" effect on the flow of air.

Once again, should I run into overheating issues I will start with baffling and go from there.

The paint is Krylon base grey primer + a can of Krylon "Make It Stone!" in grey. I highly recommend that you use a primer paint because it makes the application of the stone finish considerably easier and more consistent. The finish texture is similar to stone pottery and the like. It does NOT feel like those 90's popcorn ceiling textures.

 

[AKNick]

Ok, just making sure! I misread what you said about cutting the area in front of the engine. my bad. I really need to get my act together, create, and post the way I've been baffling.... I've been holding off on the baffling because of my choke geometry issue with my DA.

So this paint is fuel proof? or do you have to put some sort of protective coating over it like a gloss? It looks pretty sweet.

I must say, your work appears seamless, well done!

 

[Steve_JR]

I don't know if it is technically fuel proof but I know many who have used it without the fuel breaking it down over time. I did not apply a clear coat over it - just primer and stone finish.

Thanks for the compliments! I would love to see a good write-up on baffling

 

[AKNick]

Went ahead and mounted the throttle servo on some ply rails that I made and epoxied onto the LH side.

Here you can see the rail I added.

With using my throttle linkage (Du-bro blue/gold rod) you can figure out where it's going to go through the firewall.

Installed the throttle servo on the rail using some allen head screws purchased from Tail Dragger RC a while back. They are pretty nice if you cannot fit a screwdriver inside, plus they'll give you the torque you need without stripping a phillips head!!

And of course once all that's in place, I can install my ball links to the desired length. If you don't own a ball link driver, I highly recommend them!! SO nice. Since I have carpel tunnel - I love having tools that keep me from gripping small things!!

Next I'm going to post my bellcrank choke system.

 

[Bipenut53]

Wow [MENTION=3929]AKNick[/MENTION], that is really nice! One question though, are you going to cut a hole in the firewall where the carb is?