specialFX

Hi Folks!

After some building on my first jet i decided to share my project with YOU, the community. First of all i want to state that this community is an increadible source of knowledge for any newcomer. Even, if myself, most of the time just searching the existing threads, itĀ“s a great source of information.

Some years ago, at about Ā“93 to Ā“95 my friend Franz and me built three turbines. The last one really worked, but our jobs and personal issues threw us away from the jetcommunity. Last summer, after my new buddy Alex had really great success with his first jet, a Black Shark from jetwelt.de, and myself being back into the rc-world for some years, i was really thrown into it again. So i decided to look for a jet trainer with a simple setup and the look of a real jet, no roo, spot or even a shark, even if it prooved to be a reliable and handsome bird.
After some research i found the Su-27 Sport from Jet-team Liebetrau. It looked awesome, had this simple setup i was looking for and in a german forum i got very positive response about this bird. One of the pilots already flying this plane, this very nice guy being Andreas Scholl, was on holidays in Austria and we had the opportunity to see it in life action. I took some video footage that can be found here:
[link=http://www.andreasscholl.de/Jets/sportSU/sportsu27.htm]Su-27 from Andreas Scholl[/link]
Thereafter my buddy Kurt and myself ordered two kits. This kits were delivered at the Nitro Days in Punitz/Austria end of september.

And here our journey began. In a positive way!
We got two very nice kits, the composite-parts being of really good quality, flying surfaces beeing foam cores with obechi-sheeting in very good quality, pressed without leading edges and being realy true, tips glued on and already sanded, light and of equal weight on both sides. Being flown only by Tailerons without ailerons or flaps, the wings are almost ready to finish, just (optional) rudders to install, really nice. But itĀ“s a kit, no ARF at all. Wing-mountings have to be installed, but itĀ“s no problem for any builder who has built a kit before. But more on this as time will come. The kit is delivered with building instructions beeing ok for any kit-builder, without plans (that are really not neccessary) and a CD with approx. 170 pictures of the actual build. Very promising at all!
Thereafter, any time we had any question, Peter Liebetrau was as helpful as he could, really nice to be in touch with him, an outstanding person in the jet-business.

Long words of introduction, lets begin!
Following are two pics of the kit in the state of delivery;-)

specialFX

Hi!

At first i decided to exchange most of the formers and stringers by nomex/glass laminate. I want to state that this was really NOT necessary at all, but after having the possibility to do so i decided this way. And i like to modify planes in my way. A wheight comparison to the original formers showed up that i could save approximately 300-350grms of wheight by this step. but i think itĀ“s a reasonable amount of additional work to do, because every joint has to be laminated, no butt-joints at all;-)
Instead of the original lite-ply i used 3mm nomex with 2x163gr glass on each side on the structural important formers and 1x163gr each on not so importent parts. This nomex-plates were built fore me by my buddy Xandi, being a genius in glass/carbon-technology. HeĀ“s building F3B-planes and hotliners in full glass/carbon/aramid in exceptional quality, i would name it NASA in RC!
Here are some shots of my replacement-parts;-), but as stated befor, absolutely not necessary, none of the european builds of this plane iĀ“ve seen so far used something like this, and all went well and showed up with a real good dry-weight!

specialFX

Thereafter the real build started. The first cut in the virgin fuselage started. After being this plane a former ducted fan queen in the european scene, the fuselage was the original one from former ducted fan-eras with some serious strengthnening in some lethal areas.
But here the real big constructon-idea showed up. Being a twin, in the Sport-Su the turbine is mounted inbetween the big engine-nacelles of the original airframe. Already as being known for the enthusiast planewatcher, this solution is almost invisible in flight! Even after the actual version has an engine-cover to provide FOD and making the engine more invisible. If you donĀ“t want to believe, watch the images on Peter LiebetrauĀ“s homepage, i think itĀ“s Fridhelm Schafers plane that was to incorporate the engine cover as the first one, a fantastic idea!
Pictured here are the cutouts in the fuselage and some former-installation into the fuselage. The formers were fixed by small drops of CA and then laminated into the fuse with some glass-strips (30mm, aprox.200grms) For each former-installation the fuse was placed as stated in the instructions on itĀ“s tail end, for avoiding distortion of the this so far relatively soft fuselage.

specialFX

And lets continue!
As a next step i decided to reinforce the fuselage in the main-former area by a strip of approx. 12cm (=5") of carbon cloth with a weight of ca. 200grms/mĀ² to give this area the stiffness i desired. Not neccassary at all, but for my confidence into the gear/wingmounting-area it was desired by my not so well educated jet-confidence
In this step the nosecone was also cut away.
We got our kits delivered personally by Peter therefore we had to cut the nosecone ourselves, as itĀ“s done normaly for package-size and we got a special-deal about that not had been done. Besides, we had therefore the opportunity to make the cut approx. 10mm back of the original position exactly in a panel-line, which we preferred;-)

specialFX

Much work to do, so letĀ“s go on!

Thereafter the main former was brought in. Nothing unusual here, after fixing with CA-drops the joint was made secure with some thickend up epoxy and then laminated with some glass-strips, also 30mm, as almost in any place was used And as allways, the fuselage was brought to a stand on its back end for minimising distortion!
If my thread comes out to lengthy, tell me, otherwise iĀ“ll bore you with some more stuff like this. But i think jet-newbees should be able to take some usage of this thread. But itĀ“s your decision!

specialFX

At this stage of building there would have been the main-stringers to be implemented. After watching AndreasĀ“s plane and examining Peters pictures on his CD i concluded, that his airbrake-solution wasnĀ“t exactly what i wanted. Therefore i had to go over this detail;-)
Therefore i took the dimensions of the original fuselage by really basic means, that is i ruptured some electric wire around the portions of interst and took the slices of this portion of the fuse. this pictures can be seen below. This slices i ported to 3DMax (most of you will know) and began my thoughts on my solution to this problem. As i am in the belief that a working airbrake is a necessary option to enrichen the flight envelope of a real fighter plane this had to be taken special care about. As i witnessed AndyĀ“s flight in St. Johann, his airbrake didnĀ“t fully close on fast flybys and was not able to open fully at medium speed flybys. Not a satysfying option (in my opinion at least) After looking over all the material avalible on PeterĀ“s solution, i identified 2 reasons for this problem:
1. he closed the AB by rubber-bands - obviously not strong enough at higher airspeeds
2. The kinematics of his solution was inadequate for fully deplouing the AB at higher speeds.

After some thinkabouts and some whiggling and whaggling around the components and some calculations i came up with a solution like shown on the animation sequence below:
[link=http://www.airtec.at/Airbrake_v01_Kolbenhub_4zoll.avi]AB_Solution_v01, avi, 1MB[/link]
This solution was based on the UP-Cylinder with 4"stroke. As i opted to use a WABO-Cylinder with about 150mm stroke and a cylinder diameter of 15mm it should be satisfying!
We gonna see!

[edit] the blue notes on the hand-written sheets below are of a completely different kind![/edit]

erbroens

This plane flies great and it is not often see.... keep the pics coming please!


Rgds, Enrique.

SJN

Looks good so far!

Do you think it can be flown on 2 mw-54`s ?

jescardin

My Feedback: (1)

Hi friend:

Very happy you started this thread as I also own one but find some trouble with the german instructions, even after trying with a translator.

Your comments as well as your photos will make a grat help for my building. Only one question; which retracts are you going to install?. I understand that Liebetrau set, together with oleos, is a great choice but last time I contacted him it was sold out. Please comment on this and many thanks.

Jesus Cardin

I-NAV

My Feedback: (3)

Thanks for the info. I've got one of these kits as well and plan to start building this fall.

Mike

SJN

Hi guys.

I have downloaded all the pics I can find on the net with this plane.
There is also a movie with it flying.


They are located here:
http://bornholm.adsl.dk/modelfly/files/su-27/

Christopher2

Hi,

Here is also a site whit some building pics.
http://www.neutro.fi/lennokit/su27/alaosa.htm

Hope you enjoy.
Keep up the great work,looking forward to your finish.

Greetz.
Chris

specialFX

Hi folks!

There seems to some interest in this plane, so iĀ“m happy i started the thread to share my project with you.

Hey Chris, the ZModel SU-27 is a different kt than the Liebetrau one!

Yeah Sonnich, two MW-54s or P-60s etc. would be a perfect match. With paying some attention to the wheight, it should be not heavier than a single-version with 120-160-power. But the kit is not designed for that option so considerable mods would be neccessary. But it would be awesome!

Jesus, i had a similar problem about the gear. first i wanted WABO retracts but they would not be able to deliver until end of march or so. But then i decided to buy a set of Behotec C-50s with oleos and 105Ā° retractangle on the Nose. They came up at ā‚¬500, complete with valves, tank etc. and were delivered within a week! Here are some pics of the retracts, they are state of the art. The blocks a milled out of a block of aircraft-grade aluminium, the oles have 18mm diameter and are manufactured to the highest standards and should withstand some kind of abuse

specialFX

Lets continue, spring is nearing with warpspeed[X(]
I thought it would be a good idea to first build up the AB-structure and glue it into the fuse at this stage. After cutting out the airbrake in a later step it should give a perfect fit.
I printed the CAD-drawings and made the parts out of carbonfiber laminate i made myself. Therefore i tacked two sheets togeter by doublesided tape and glued the drawings on it, so i got perfect fitting pairs. Then i aligned the two main stringers by a wooden plate with 2 slots cut in, glued the formers in place and bolted the hinges to this assembly. This whole component was then glued into the fuselage with slow curing resin.
Maybe itĀ“s overkill, but if the result will work as desired, itĀ“s worth the effort

Thomas

specialFX

After the epoxy had hardened i put in the two main stringers reaching from the main bulkhead far into the nose, gicing the fuselage enourmous strength. The nosegear bulkhead was also glued in at this stage. As allways, tack-glued with CA and secured with epoxy and glass. And donĀ“t forget to put the fuse on itĀ“s tailend while the epoxy cures, as the fuselage can be easily distorted in this stage.
IĀ“ve attached 2 pics of my special tools that i use to finger in the glass at remote positions. Very helpful. Masterbuilders might smile a bit[8D], but this thread should be useful for the not so sophisticated builders too!

Thomas

wsmalley

My Feedback: (6)

Thanks for the great thread, keep the info coming! I'm scratch building an SU 27 from Bertelli plans which-if you know- have no instructions. The pictures and data is very helpful. Got to be the sexiest jet out there!

specialFX

Hi drivers!

After having put in the main stringers and the nosegear-bulkhead the former for the removable nosecone was tacked in by CA as were the stringers and front former of the nosegear bay. Everything as in the last steps, tacking and glueing with thickend epoxy and glass strips laminated over the joints.
Sorry guys, I just have a pic of the nosecone-former, cause I by mistake deleted the pics in my digicam. But this region can be seen in a later stage, there is much work left to do, donĀ“t be afraid!
After this step the fuselage showed up very stiff but still very light at a bit over 3kg incl. nosecone. I had to wait until all this formers etc. were in the fuse before I could cut out the airbrake and the nosegear door, what I was eagerly awaiting as you all can expect.

Thomas

specialFX

Hi to all not yet bored!

Big day! Cutting out of the speedbrake. Now would show up if the CADĀ“s were right and if it was smart to glue in the complete AB-assy at this early stage I did. If I would have distroted the fuse after the AB-group was glued in, my speedbrake would pop up big gaps after cutting, when the Carbonfiber-frame would go back to ist original form and twist the speedbrake. We gonna see.
For making the cuts I used a very thin steel-disc with some kind of diamond application on it. It gives very thin cuts of approx. 0,3mm. For making straight edges I use a thin steel-ruler (an old one, of course, because the edges will be harmed in the following cutting process). This ruler is glued onto the fuse with thin doublesided tape. The pics show that the ruler can be bent around rather tight curves.
Of course the same method was used for the nosewheel door.

After the cuts were done - big grin in my face. The speedbrake showed up to have realy minimal gap[8D], absolutely no warping at all! The position of the hingline gave exactly the expected result by opening the brakeboard upwards and foreward. Not exactly scale but as expected. Up to now it was worth the effort!

Thomas

specialFX

First after opening the fuselage was to make the "lids" for the speedbrake to rest on in closed position from thin laminate similar to polyply. My buddy Xandi made this sheet for me by using "peel-away"-cloth on the surface. This gives a perfec surface for glueing. Exposed portions are easily made smooth with some filler and slight sanding. Now that the fuse was open between the main stingers, the inner joints could be laminated, as well as the backside of the nosegear-former. I think this step is very important for making this essential joints durable.
Attached are also two pics of the nosegear-area, that were lost in the last step.

I glued some liteply into the wingroots where the holes for the front and back wing dowels will be. Peter Liebetrau omits this step in his manuals but I think they are absolutely neccessary. I have some weights of very different shapes for differing tasks. The ones shown on the pic are brass-wheels with a short sticks of spruce fixed onto it with heatshrink as "antiroll"

Next step will be to install the tubes into the wings and adjusting the correct incident of the wing root. Then she will start to look SU-like

Thomas

I-NAV

My Feedback: (3)

Thomas,


Thanks! Keep it coming.

Zack Morris

Thanks Thomas!

Following your progress daily and appreciate your sharing.

specialFX

Hi dear Jet jockeys!

As stated last time, itĀ“s time to give the girl her wings. The paper-tubes are not already premounted into the wings, but a brief testfit showed, the factory drilled holes are spot on and the wingroot fits almost perfect to the fuse.
Peter describes this step in the manuals and the pics on the CD should clarify the last black holes in ones mind. First I put the fuse on my flat table. It rests on the main former. Now you have to pack up the foreward fuselage area to bring the nose of the plane to a height of 130mm above your building board. One of the pics shows the measurement (itĀ“s a pic from Peters CD). This step brings the fuse in its flight-position.
As my table is not big enough for the whole fuselage (total length of the plane is 2,42m!) I positioned it that way, that i could measure the noseheight above the table. I made a support in the region of the forward end of the nosegear bay and marked the position of this support on the fuselage. Then I moved the fuse with the support that far foreward, that i was able to measure the height of the leading- and trailingedges of the wings above the table.
PeterĀ“s manuals demand an incident of positive 1Ā° for the root. With a rootcord of 570mm this equals 9,95mm, a measurement of 10mm shoud do it. There are no marks on the fuse to assist you in this process. The dihedral of zero was judged by looking from behind. DonĀ“t be fooled by an optical illusion, the wings have a washout of 2 degrees built in. I made 2 supports for the trailingedges to have no problems finding this position again when glueing in the tubes with thickened slow epoxy. A little bit of waxing the fuselage and the tube in the fuse could be very useful

specialFX

After the epoxy had cured the root section was marked onto the fuse for future reference. Then the wings were removed and some tape put on the root of the fuse. After waxing the tape, the wings were put on again with some very thick epoxy, allmost like butter, on the roots. This step gave me a perfect fit of the wings without any gap.
The position of the dowels is marked on the fuse and drilled with an 8mm bit. Put the wings on again and mark the position of the holes on the root. Then drill the root. I inserted the Aluminium dowels into the fuselage, test fited the hole positions in the wing using the premarked wingroot on the fuse, remove again, put in some 5min epoxy and reattach using the reference lines and the supports from the prvious step to ensure the correct incidence angle.
On the pics you can see that just a thin film of epoxy was needed to fill the gaps on the root.

And on the last pic, she begins to look like the most beautiful fighter jet around[8D]

Feel free to add comments or questions

greetings
Thomas

specialFX

Hi folks!
I think iĀ“ll tell you more on this stuff tomorrow. Today i fitted the horizontal tail feathers, but thatĀ“s a completely different story. IĀ“m too drunk to state the facts as they were and had a really nice time at my work. Met with my buddies, had great fun and realized that some prezision stuff is not the thing to do tonoght, but i like it. My buddies are great!

Expect to see some follow up

Thomas

Carbon-Customs

which turbine will you use for this bird, do you have a photo of the engine cover?