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Experimental J-3 with PA-18 wings and Subaru motor

Mikhail

Registered User
Primorsky kray, Russia
Greetings, everybody. I'm new here and want to share a project I almost finished few month ago. It's a Cub airplane with J-3 fuselage and PA-18 metal/fabric wings with flaps and 2x50L fueltanks. The engine is Subaru EJ22E, untouched injectors and stock ECU. The wheels were taken from the PZL Wilga. The plane is completely self-made by drawings from WagAero, but with correction for russian assortment of metal.

Before cub I had a Flylab Tucano ultralight, so I can't compare my Cub with other Cubs. As for perfomance - it has a 5 m/s climb rate (1000 fpm), pretty short landing and takeoff roll (three-point landings is about 50 and takeoff is 70 meters on grass strip with no wind and ~17C). The ground-adjustable propeller and reduction drive are tuned so the plane have 4500 rpm at full throttle and 3200-3600 rpm in cruise.

It's not completely finished, because it requires some minor adjustments and upgrades, but at this moment it already fun to fly airplane

Best regards from Russia
Mikhail

P.S. appologise if there are mistakes, English is not my native language.
 

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Welcome Mikhail, where in Russia are you? We in the western world are not that familiar with small plane flying in your country. Occasionally we see someone like yourself who is able to enjoy private flying.

I myself have visited Moscow many times, but having used Sheremetyevo airport, there were no small airplanes.
 
Here's some earlier progress photos.
I used a car parking brake lever for flaps, and it works wery well for me. :smile:
A couple of words about fabric covering. In Russia we often use specific technology: we use synthetic thermo-shrinking polyester fabric in combination with special lacquer. We use 3-4 layers of lacquer with thinner, then 3 layers of lacquer mixed with aluminum powder to protect the fabric against UV. Such covering lasts for about 10 years even if keep the plane without hangar.
 

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Mikhail, I installed an EA-81 Subaru in a RANS S-7 and flew it for 1300 trouble free hours about 20 years ago. As you know by now, most auto conversions are a bit heavier then an aero engine, but as long as the aux systems (fuel, electrical, reduction system, and other "minor" items) are done correctly, the engines themselves can be quite reliable. Running auto fuel in them is a given!

I went to the trouble of getting a Subaru placard off a junked car, and while I was at it I also took the horn. It proved to be handier then one would think, and was always good for a laugh of course. Nothing like making a low pass, while honking.
 
I've never specifically looked into it, but I haven't ever heard of much if any private, general aviation type flying being done in Russia-- let alone homebuilding.
Especially if that's the case, I salute you for accomplishing what you have.
I'm not a big car engine fan (except in cars), but that looks like a very cool, fun to fly airplane.
 
Nice Cub. We here in the USA have it luckier than most when it comes to our personal aviation freedoms. I have many trips through Khabarovsk and I do not recall seeing any civilian aircraft like a cub.
 
I agree. My impression of Russia has not included light aircraft, so this is a hopeful sign. There is so much we don't know about modern Russia.
I became intrigued with Russian literature a half century ago and got far enough along to be able to read simple short stories in Cyrillic. Really nice to hear you have Cubs there!
 
Here's some earlier progress photos.
I used a car parking brake lever for flaps, and it works wery well for me. :smile:
A couple of words about fabric covering. In Russia we often use specific technology: we use synthetic thermo-shrinking polyester fabric in combination with special lacquer. We use 3-4 layers of lacquer with thinner, then 3 layers of lacquer mixed with aluminum powder to protect the fabric against UV. Such covering lasts for about 10 years even if keep the plane without hangar.

I'd like to hear about the gear reduction. I don't know much about them.

Love the radiator!
 
as long as the aux systems (fuel, electrical, reduction system, and other "minor" items) are done correctly, the engines themselves can be quite reliable. Running auto fuel in them is a given!
It's true, in Russia we have some good statistics with fuel injeted subaru and honda motors (EJ22, EJ25 and Honda D16, L15). Carbed old Subies are also good, but they're too old and it's nearly impossible to find one in a good condition.
You idea with car horn sounds good, I should check local car junkyard for it :smile:

Nice Cub. We here in the USA have it luckier than most when it comes to our personal aviation freedoms. I have many trips through Khabarovsk and I do not recall seeing any civilian aircraft like a cub.
It's sad, but I must agree with you about aviation freedoms. We have poor law regulation of private light aviation in Russia. And yes, my cub for now is the only flying Cub in our province. Next time you can make a detour to Vladivostok and contact me, if you wish, I'll make a tour for you to our local small aviation sanctuary )

I'd like to hear about the gear reduction. I don't know much about them.
Love the radiator!
The gear reduction drive was made here, in Vladivostok. It has a 1:2.23 reduction ratio and is meant to be installed on Subaru engines up to 260 Hp. You can google VladTehnoMarin and find out more about it. I'm not sure about quality, I have bought it not so long time ago, but people who using theese drives mostly give a good feedback. The previous gearbox (the purple one on the photo above) wasn't last long, it was made a few years ago in Belarus and has a defected gears, so I decided to buy a proven one.
As for the radiator - it's from VAZ-2108 car family. It fits very good, because the pipe exits are placed on one side.
 

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Neat thread. Thank you for posting your build story and pictures. Your English is excellent. Much better than my Russian!
What is your occupation/trade?
 
What is your occupation/trade?
I'm not sure about the right name of my occupation in English, but I belive it sounds like Computer specialist, or System administrator, or Computer network specialist... something like that. My job always was around computers, the aviation and building/flying is my hobby.

To mantain thread, here's a video with a couple of boar packs. They were just in one mile from our airfield. Sory for shaked hands - I'm not that skilled yet to drive and shot simultaneously at low levels )
[video]https://drive.google.com/open?id=1CdQsMvRpfAzFwuYUp-1sffite8f7bEBA[/video]
 
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As I mentioned above I have PZL-104 Wilga's rims installed on my Cub. It's neraly impossible to find 500x200 millimeters Wilga's tires, so I'm curious about if 6x8.50 AirTrac will fit. Any suggestions?

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Over here that 500X200 tire works out to essentially an 8" diameter rim, 7.87 to be precise.
The 8.50X6 is a nice tire size but will not fit your 200mm rim.

Thanks for the link, Charlie!
In this case the size 500x200 isn't mean that the rim diameter is 200mm, it describes the diameter and overall width of the tire: 500mm is a diameter and 200mm is the width. The rim diameter is about 6", but I'm not sure about this yet. I need to disassemble the rim and measure exact diameter.

As for the vehicle tires I have some experience with my previous ultralight (actually it was 8" ATV tires):
 

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If I read this right and my math is done right the diameter where the tire bead sits is about 4 ½"

Stomil Tire from Poland. Fits Wilga Aircraft. Tubeless

  • Tire size 500x200 version 1
  • Number of layers 4
  • Tread pattern AT4
  • Variety TL
  • Overall diameter - new tire 505mm
  • Overall diameter - in service 520 mm
  • Section width - new tire 195 mm
  • Section width - in service 200 mm
  • Static radius 208 mm
  • Inflation pressure 0,20-0,02 MPa
  • Maximum speed 120 km/h
  • Rim - Flange height 152,4 mm
  • Rim - Width between flanges 127 mm
  • Rim - Flange height 18,8 mm
  • Rim / Ledge width 25 mm
  • Standard WT-70275

Your picture, that is a good job shaving the lugs off that tire if you did that locally.
 
If I read this right and my math is done right the diameter where the tire bead sits is about 4 ½"

Stomil Tire from Poland. Fits Wilga Aircraft. Tubeless

  • Tire size 500x200 version 1
  • Number of layers 4
  • Tread pattern AT4
  • Variety TL
  • Overall diameter - new tire 505mm
  • Overall diameter - in service 520 mm
  • Section width - new tire 195 mm
  • Section width - in service 200 mm
  • Static radius 208 mm
  • Inflation pressure 0,20-0,02 MPa
  • Maximum speed 120 km/h
  • Rim - Flange height 152,4 mm
  • Rim - Width between flanges 127 mm
  • Rim - Flange height 18,8 mm
  • Rim / Ledge width 25 mm
  • Standard WT-70275

Your picture, that is a good job shaving the lugs off that tire if you did that locally.
152,4 / 25,4 = 6" so I suppose the Wilga's rims are 6" and 8.50x6 should fit well. But are theese 8.50x6 Airtrac are allowed to be installed without tube?
 
I'd look into Aero Classic smoothies from Desser. They make 8.50 - 6 in tube and tubeless. The tube type is ~10 pounds but of course requires a tube. The tubeless does weigh a little more, I've heard ~13 pounds. I'm guessing without the tube they needed to stiffen the side wall in order to run as tubeless. I use the tube type on my Savage Cub as the tubeless had not come out yet when I purchased them. I get great wear and they are a pretty soft ride. Some even use them up to and including C-180s. In my opinion, that is a lot of weight on them but they work perfect on 1000 to 1800 gross weight planes.

Link to the tubeless [FONT=Verdana,Arial,Tahoma,Calibri,Geneva,sans-serif]https://shop.desser.com/pc_product_detail.asp?key=BAB6FA72A07F4FEDAE85717E1387DCF3[/FONT]
 
152,4 / 25,4 = 6" so I suppose the Wilga's rims are 6" and 8.50x6 should fit well. But are these 8.50x6 Airtrac are allowed to be installed without tube?

I read The Flange Height as the outer diameter of the rim flange. If that is actually the bead seat diameter then you have no problem with 6" tires.
 
Hi everyone! It's time for me to practice some storytelling.
Okay, as you can see form the photo below I have had a bad day. Yes, it was "not so good" engine-out landing. It was all my mistake, I forgot to switch on the fuel tank lines. That day I noticed some oil pressure arrow slightly twitching, but inspection didn't showed any problems and I decided that it is poor quality soviet-made oil pressure sensor glitching. I have 2 oil pressure sensors: one is stock lamp indicator, showing that there is no pressure at all, and second is sensor with arrow, showing the exact oil pressure value. That day oil pressure indicator arrow was twitching between 3 and 4 Bar, that's normal value, but there should not be any twitching. So, that day I decide to continue my flying experences with twitching oil pressure indicator, I was sure that everything is allright with oil and oil pressure (and was actually right). So I was in couple of miles from airfield at about 150 meters altitude when engine suddenly stopped. First of all I call to mind about fuel switches and switched them on, trying to start engine, but it won't start. Then I switched on the second fuel pump, and engine starts for some seconds and stopped. As it seemed to me - there was no time to try to start the engine further, so I concentrated at the controls. I have the powerlines ahead and rough soft potato field with some copses below within reach. The only chance for safe landing at that moment was a very rough road. I retract the flaps and pushed the stick, slipping under the powerlines, ganing some extra speed, levelled above the road. The speed was too high and the straight part of the road too short, so I started to grind the airplane to the road to use brakes as soon as possible. As I said, the road was very bumpy and rough and I have broken the left tailwheel chain (I haven't differential brakes - for your better understanding), after that the airplane throwed right. The speed was too low for the rudder to take effect, so I wasn't able to recover from driving to the right side of the road with about one meter deep ditch in it. So I have my right wing broken and the cherry on the cake is one broken propeller blade and cracked engine cowl. So what about the twitching indicator? It was actually a broken fuse on the fuel pump that I didn't take in mind. When the fuel sucked from the supply tank, the fuel pump began to suck the air and it's load exceeds the fuse nominal, then fuse goes finally out. That's why I can't start the engine in flight, I forgot about the fuse. As for the second fuel pump - it takes fuel from the higher part of the supply tank and the fuel haven't reached proper level. All I was had to do is to press and hold the fuse.

To be continued...
 

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It can be repaired. You certainly aren't the first nor the last to bend an airplane. Unfortunatley I know how you feel.
 
Here's some photos about what exactly happened to the right console. As you can see - longerons and a half of all ribs need to be replaced.
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That's a lot of work, actually, the whole console needs to be rebuilt.
 

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2 spars... replace time is less than 4 hours... and some leading and trailing edge... then the major time is to do the fabric & painting..
 
Not only spars, there's some bent ribs also. Fortunately I have some 0.5mm sheets of anodised aluminum, russian analog of 6061-T6, and acces to CNC machinery, so it won't be hard to make some new ribs.

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About the fabric: I have an obsession to make an all-metal wing. My plane kept under the sun all the time of the year, so I think metal wing will last longer under the UV and weather. I have enough aluminum sheets, clecoes, solid and pop-rivets. There will no be too much weight addidion since I'll remove almost all compression struts and diagonal tension strings, but airfoil will be more accurate. What do you think?
 

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I think properly prepared fabric will last a very long time. If going to cover with aluminum I would stay with a light gauge and not remove any internal structure. It will be interesting to see what others think. Get her back together and flying!
 
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