Highly Modified AK Models SU-27 Build Thread
 

Summary

Hello SU-27 fans,

I've read and re-read the "AKM SU-27 Does Look Good" thread on RCU several times and it inspired me to build one of my own. I'm a builder at heart who sometimes flies (to test out the build) and like my handle implies, I tend to heavily "mod" every kit I build. Most of the time just for the coolness factor. Since I'm modding the original kit so much, I started my own thread. For this kit I plan to make three main mods*:

1. Full flying stab/ailerators
2. Movable L.E. flaps
3. A Speed brake

* and other scale resembling mods here and there

I understand that these mods are not needed and will/may degrade the performance a little, but the coolness factor far outweighs that[8D]. The engine will be a Jett 90L of course.

The Kit

The kit is sold by [link=http://www.ak-models.com]www.ak-models.com[/link]. It's laser cut (the parts actually fit together) and for $124.00 you can't beat the price!

Covering Design

Lastly, this will be my covering design. It's a MIG-29, but it is absolutely beautiful.

http://img379.imageshack.us/img379/5875/24tp.jpg

http://img150.imageshack.us/img150/6540/40hf1.jpg

RE: AK Models SU-27 Biuld Thread with many Mods
 

Full Flying Stab/Airlerators

The original kit uses epoxy bearings and control rods to move the elevators (See Figure 1)

http://img55.imageshack.us/img55/408...ction479lv.jpg
Figure 1

My design will use 1/4 dia aluminum torque rod epoxied in the stab itself (See Figure 2). This is the same design as [link=http://www.savagelight.com/]savagelights'[/link] SU-27 ailerators but it's smaller so I scaled up the dimentions. Almost bought that one over the AKM but it's electric and I'm not ready to go there yet. The aluminum torque rods will be enclosed in a 1/4 in ID carbon fiber glide tube epoxied into the fuse.

http://img55.imageshack.us/img55/7826/elevonmac9fc.jpg
Figure 2

I'm going to use control horns purchased from Cermark. These are the same milled aluminum control horns used in their F-16. I have not seen nor heard of a better control horn for high speed full flying stabs. Surprised they don't sell them commercially [sm=confused.gif]? Here's a pic of the control horns installed in the F-16.

http://img206.imageshack.us/img206/7169/ay747711ev.jpg

RE: AK Models SU-27 Biuld Thread with many Mods
 

Got a chance to crack the kit open and start building.

Began by building the stabilizer per the instructions. Since I'm not using the torque rod method to control the elevator I filled in the open slots with scrap balsa.

http://i60.photobucket.com/albums/h3...n/IMGA1018.jpg

Took me about 2-3 tries building the epoxy bearings for the rudder. Found the best way was to file a grove in the center the aprox. diameter of the torque rod, fill with a mix of 30 min epoxy and milled fiberglass (for added strength).

http://i60.photobucket.com/albums/h3...n/IMGA1032.jpg

http://i60.photobucket.com/albums/h3...n/IMGA1027.jpg

RE: AK Models SU-27 Biuld Thread with many Mods
 

Next, I taped off a scrap peice of balsa and used that as a dam so epoxy would stay where it's supposed to. Then, lubed the torque rods with Vaseline and pinned it to the building board.

http://i60.photobucket.com/albums/h3...n/IMGA1033.jpg

http://i60.photobucket.com/albums/h3...n/IMGA1035.jpg

Worked like a charm!

http://i60.photobucket.com/albums/h3...n/IMGA1039.jpg

RE: AK Models SU-27 Build Thread with many Mods
 

Hi MRM.. thats a very tidy looking torque bearing there[sm=thumbup.gif]

RE: AK Models SU-27 Build Thread with many Mods
 

I'll put a link to this thread over at the old thread so all off us can see your progress.

I plan on doing the same stabilators set-up as you so I'm very interested to see how yours works out.

I do have one question, though. You say you're going to use the Cermark aluminum horns but you say they don't sell them. Did you get them out of a crash F-16? Or did I misread what you wrote?

Thanks for the thread

Don

RE: AK Models SU-27 Build Thread with many Mods
 

Actually I got lucky becasue they had some damaged ARFs lying around and sold me a set off one of them. Charged me $14.50 [:@]! They were worth it though. I have to go buy an extra set because one of the screws that came with it stripped and I can't drill it out [:o].

Mods

RE: AK Models SU-27 Build Thread with many Mods
 

How did you come up with the location (foward and aft) of where to place the aluminum shaft? The weight and aerodynamic balance of the surface is important.

Rich

RE: AK Models SU-27 Build Thread with many Mods
 

I started a thread in the aerodynamics forum to pick their brains on the best method. If you want to check it out: [link=http://www.rcuniverse.com/forum/m_4225798/tm.htm]CLICK HERE[/link]. They gave me a little insight and a good place to start, but I wanted to be sure so I broke out the calculator and got to work. My calcs showed it to be in about the same place as suggested. Did some more digging and found the best (and easiest) method by far on [link=http://www.airfieldmodels.com/information_source/math_and_science_of_model_aircraft/formulas/mean_aerodynamic_chord.htm]www.airfieldmodels.com[/link]

Here's a screen shot (Figure 1):

http://i60.photobucket.com/albums/h3...Elevon/mac.gif
Figure 1



The rod must be placed 20%-25% on MAC to be effective. All three methods above yielded a distance of 4.40 in from the tip of the L.E (Figure 2). I shouldn't need to balance it since the rod will be located 25% on the MAC, but I am anyway just for grins :D. What's the point of going to all this trouble to do a half a@#ed job. I then plan to fill in the crevis created by the rod with 30 min epoxy. Lastly, seal the entire stabilator with medium weight fiberglass.

http://i60.photobucket.com/albums/h3.../ElevonMAC.gif
Figure 2

RE: AK Models SU-27 Build Thread with many Mods
 

Kit comes together very easily. Completed the fuse and engine sides. I found using the tape & strip planking method worked better to keep the CA from hardening on the outer skin (Figure 1).

http://i60.photobucket.com/albums/h3...n/IMGA1048.jpg
Figure 1


Next, installed most the fuse formers with thick CA, except for the landing gear and firewall formers which I used a mix of 30 min epoxy and milled fiberglass (Figure 2).

http://i60.photobucket.com/albums/h3...n/IMGA1052.jpg
Figure 2


I am constantly reminded how well this kit was designed. Case in point, here is a photo of the fuse sides (Figure 3). In every kit I have put together, you have to use a 90 degree square to install the formers. This kit has the placement and angles of all the formers lasered on the fuse sides themselves!

http://i60.photobucket.com/albums/h3...n/IMGA1054.jpg
Figure 3

More to Come,

Mods

RE: AK Models SU-27 Build Thread with many Mods
 

Thanks, this was my first epoxy bearing.

RE: AK Models SU-27 Build Thread with many Mods
 

Looking good Mods.
You picked a great scheme to do, but I will warn you that it is a bear to translate from the Mig29 to the '27 planforms. I spent more time converting scaling the scheme on the pc, than in actual covering time. I am not sure what good photos you have, but if you look, the bottom of the right wing has the Mig logo on it, so what I did was cut out the Sukoi log in blue and replaced it. That is the only change to the scheme that I have done.

Keep the pics flowing!

Spar

RE: AK Models SU-27 Build Thread with many Mods
 

Hey Spar,

I'm glad you approve of the covering scheme. Do you mind posting some pics of the bottom. I've searched the net for hours and can't seem to find any.

Thanks,

Mods

RE: AK Models SU-27 Build Thread with many Mods
 

Since this was my second choice, I have few photos as shown below.

RE: AK Models SU-27 Build Thread with many Mods
 

I would if I could, but I am in Norway this week and all my reference stuff is home. It will have to wait until I return. Vic also posted some very good pics, and take notice of the engine bays. If you look at the first picture, notice how the white on the fuse flows down a bit and the blue still creates that 'lightning bolt' look... especially in the front area and where the retracting wheel is shown. Really examine your photos and look for those subtle things that most would overlook (look at the jagged LE of the Stabs!).

Spar

RE: AK Models SU-27 Build Thread with many Mods
 

For any of you who may want to use this paint scheme, I have uploaded a large video of the Mig at the following address:

http://download.yousendit.com/0422A0E85FAF5360

The file is nearly 39 megs but it is well worth the time to download. There is an interesting dialog at the end of the video where the pilot shows the functionality of one of the engine nozzles. Enjoy ! !

RE: AK Models SU-27 Build Thread with many Mods
 

Today I began by strip planking the fuse bottom sections together and attaching it to the formers.

1. Taped two sections together with masking tape. Flipped the section over and spread medium CA in the crack.

http://i60.photobucket.com/albums/h3...n/IMGA1056.jpg

http://i60.photobucket.com/albums/h3...n/IMGA1057.jpg

2. Using a paper towel with a few drops of acetone and wiped off the excess. Flipped it over, removed the tape and wiped off the other side.

http://i60.photobucket.com/albums/h3...n/IMGA1059.jpg

3. Connected all the fuse bottom sections and attached them to the former bottoms with thick CA.

http://i60.photobucket.com/albums/h3...n/IMGA1064.jpg

RE: AK Models SU-27 Build Thread with many Mods
 

Used a mix of 30 min epoxy & milled fiberglass to attach the firewall and landing gear plate to the bottom.

http://i60.photobucket.com/albums/h3...n/IMGA1066.jpg


Next. I wanted to make sure that glue got to all the formers, so I poked holes in the sheeting above the formers and dripped thin CA into the hole.

http://i60.photobucket.com/albums/h3...n/IMGA1065.jpg


First and foremost, I HATE sanding. That is why I bought and use a razor plane :D. Using the razor plane, beveled off the corners.

http://i60.photobucket.com/albums/h3...n/IMGA1060.jpg


Then, wet down all the corner sheeting with water, waited for 5 min, then razor planed some more until I achieved a rough rounded shape.

http://i60.photobucket.com/albums/h3...n/IMGA1061.jpg

http://i60.photobucket.com/albums/h3...n/IMGA1062.jpg


Now I can add the side formers and start making it look like an airplane. Should start the ailerator mod this weekend.

More to come,

Mods

RE: Highly Modified AK Models SU-27 Build Thread
 

very impressive nozzles !!! thx for sharing :)

RE: Highly Modified AK Models SU-27 Build Thread
 

Little more progress....

A much as I hate sanding; it is necessary, so I rough sanded the fuse center and prepared it for the side formers (Figures 1 & 2).

http://i60.photobucket.com/albums/h3...n/IMGA1069.jpg
Figure 1

http://i60.photobucket.com/albums/h3...n/IMGA1072.jpg
Figure 2

__________________________________________________ _______________________________________


The good news is that my supplies arrived from Tower Hobbies and [link=http://www.acp-composites.com/acp-tube.htm]ACP Composites[/link] via UPS (Figure 3):

1/4" dia Aluminum Rod from KS Metals
9/32" OD Brass tube from KS Metals
1/4" ID Carbon Fiber Rod from ACP

http://i60.photobucket.com/albums/h3...n/IMGA1074.jpg
Figure 3

__________________________________________________ _______________________________________


Bad news is that it looked like the UPS staff took an axe to my brand new Carbon Fiber tube (Figure 4) :(! The funny thing about it is that they tried to tape it back together and continue shipping it like I would not notice (Figure 5)[sm=lol.gif]. Thanks Brown [sm=thumbdown.gif].

http://i60.photobucket.com/albums/h3...n/IMGA1077.jpg
Figure 4

http://i60.photobucket.com/albums/h3...n/IMGA1078.jpg
Figure 5

__________________________________________________ _______________________________________


The bad news turned back to good news when I discovered that the aluminum rod did not fit inside the carbon fiber tube anyway, but it did fit perfectly into the 9/32" brass tube with no slop whatsoever (Figure 6) :D. So now I will use the 9/32" OD brass as my glide tube and the 1/4" aluminum as my control horn. All in all, it was a good day.

http://i60.photobucket.com/albums/h3...n/IMGA1076.jpg
Figure 6

More to Come,

Mods

RE: Highly Modified AK Models SU-27 Build Thread
 

All,

I did not know this but AKM is coming out with and F-16 propjet soon! There is a guy who got one of the first prototypes and he set up a thread for it in the kit builders section. For those of you planning to use the full flying stab mod and can't buy the Cermark control horns, his control horn set up is pretty ingenious (and easy). We're on parallel paths so check him out: [link=http://www.rcuniverse.com/forum/m_4157678/anchors_4262031/mpage_1/key_/anchor/tm.htm#4262031]CLICK HERE[/link]

Mods

RE: Highly Modified AK Models SU-27 Build Thread
 

I hope he gets the it done soon too, Ive been waiting for the F16 along time now .The cermark arf is just to expensive to ship over to Aus..hope this is available soon!!!

RE: Highly Modified AK Models SU-27 Build Thread
 

I just saw this in a thread about the Jet Legend T45.

www.rcuniverse.com/forum/m_4262306/tm.htm

Tony.;)

RE: Highly Modified AK Models SU-27 Build Thread
 

That makes me so wish I had a milling machine :(.

RE: Highly Modified AK Models SU-27 Build Thread
 

The Stabilator Mod

I've spent the last three days designing the stabilator mod and spent the entire day woirking on it. I think it might work.


Got the tail section assembled.

http://i60.photobucket.com/albums/h3...n/IMGA1080.jpg


Once I squared the stab with the fuse, I drew refernece lines on it so I can quickly do it again later (Figure 1).

http://i60.photobucket.com/albums/h3...n/IMGA1084.jpg
Figure 1


Drew another line where I plan to separate each stabilator from the stab (Figure 2).

http://i60.photobucket.com/albums/h3...n/IMGA1083.jpg
Figure 2