Idigbo

Hi folks. A few years ago I had a Yakovlev Yak 3 at 1/4 scale. I absolutely loved flying it but was never happy with the motor, a Mackay 75cc. It would only be reliable when it was 4 stroking the model was upright, roll it over and it leaned out. I always planned to change the crappy Mackay 75 for a Zenoah 62 but never did before the piece of junk stopped in the wrong place and I tried to stretch it back to the strip. Just at the point you think 'cor, I got away with that' it flicked in at only a couple of feet and the damage was pretty spectacular for such little height. One retract snapped off at the top, the other buckled beyond recognition with the associated linkages a bit beyond twisted. One wing panel slapped the runway and was pretty much rekitted outboard of the snapped off u/c leg, the front end was frightened a bit as were the wing mountings etc. Various other dings and scrapes from getting walloped by the flailing u/c components as they made a break for it. But it was all there still, just some of not attached! The model always flew beautifully, very tame for such a small heavily tapered wing, bit it was always a bit bland, no detail and too bright on the paint front. There were also some glaring inaccuracies which bugged me, so now I get the chance to do it how I would want it. Here's a few pics of it in better days. I started some of the repairs straight away and picked away at some others between other stuff happening in the workshop. But now its time to give it more attention.

Ian.

Idigbo

Like I said above, some of the repairs were done as soon after the incident as I could, since I knew that if I didn't I'd end up giving the model away or summat. I also now have the opportunity to do some mods to the model which will improve its scale looks and practicality. The list of mods I wanted to do include nearly doubling the dihedral as it always was too flat, some outline changes, proper gear doors but perhaps the most involved is scale cooling. The outgoing air already goes through a duct in the fuselage, coming out of the radiator under the cockpit, but the plan is to have ingoing air through 3/4 or so of the rad inlet, plus the leading edge ducts too. This involves fairly drastic mods to the wing centre section and the retract actuation cylinder, so since the area is already broken now is a good time to do it!!

Ian.

Idigbo

The wing was tacked back together (ages ago) to keep the shapes and sections right. The spar strip wood was undamaged, but the shear webs and the ribs took a beating. They were replaced one by one and all glued up. The sheet was hacked back to good but when I resheet it I might do the lot, it may be just as easy to do that than scarf and feather in the glass cloth etc. We'll see. The retracts were also mostly repaired over a year ago, to a stage they could be re installed and checked for smooth running. A mix of brazing and silver soldering is used, material is steel tube. The cylinder was always a bit undersized and sometimes struggled to lift the legs properly without rolling inverted, another thing that bugged me. One leg is a new fabrication of the original since the tubes were kinked, the other just has some new components since it was easier to remake rather than straighten. The new cylinder is from Unitracts and is now going to be situated behind the main spar, instead of in front of it where I want to chop the wing about.

Ian.

Prekin

My Feedback: (19)

Hi Ian,
your thread which you´ve started is very interesting. I´m happy, that someone show some "new" warbird. There are many of P-47, Mustangs, FW-190,etc, finally some new- Yak-3.
I´m not sure if I understand well. You have had crashed your Yak-3 and now you are rebuliding, is it right?

My friend had similar problem. He destroyed two of Yak-3 and now he has done his third Yak. Here are pictures. I think, that his last one (the green one) is the most well-done.

fokke

Hi guys , in our forum we have the same thread Yak -3 1/4 of my friend Dobri

http://www.fokkerc.com/forum/viewtopic.php?f=3&t=127

Idigbo

Great news that there are other Yak lovers out there! Please feel free to post any pics or reference etc, keeps the enthusiasm going!!

Next job is to sort the wing fixings to include the space making to allow the leading edge inlets to be used for cooling. This easier than it sounds since as the model has scale retracts, they are attached to the main spar and therefore the leading edge has no structural value and can be chopped about without too much worry. The original front dowel fixing will obviously go, replaced with a pair of facing formers much further back to allow the ducting forward. The rear radiator inlet duct will run in the fuselage, full width and its bottom surface will be the top skin of the wing. The leading edge ducts will be 'flowed' into this incoming air. Luckily, all radio items, including the receiver are positioned behind the cockpit, well out of the way of the ducts. The ducts will be as wide as possible to allow them to be as shallow as possible at the cockpit area.

Check out the racket from the nasty Mackay 75, only leans out when upright, was very unreliable any leaner!!

http://www.youtube.com/watch?feature...&v=SE2-_fNMVDw

Idigbo

The new formers all glued in, the front of the centre section is cut free to reveal a weird looking wing profile now! This fixing is just as rigid as before and has freed up the space needed for the cooling ducts nicely. Moving to the fuselage, since the firewall was loosened and access was bad to do a decent repair (oh alright I wanted a scale hatch on the top decking!!) out came the saw and the top just fell off! The Zenoah and prop driver I'm using is longer than the Mackay 75 so I need to look at either making a new spaceframe mount, or building an engine box to replace the brazed up jobster. I'm leaning towards an engine box but need to think about the exhaust, carb installation plus the in / out air situation. With the new hatch on top, the tank and some other stuff can be accessed from the top, meaning the front 8 inch or so of air in / out duct can be fixed in as part of the structure. Thats the plan anyhoo.

Ian.

vease

I don't remember seeing this model Ian. Looked great.

Hell of a rebuild but we've done similar with dads hurricane and if anyone can its you!

Actually, when I say we....... Dad has done similar with his Hurricane!

ARUP

Sure is refreshing to see something different!

Peter_OZ

My Feedback: (1)

90 degree carb bend on the 62 will make life easier. Gives it better response too plus electronic CDi

91zulu

My Feedback: (2)

Finally...a real different warbird. Where have you been hiding this one? One of my favorite Russian planes. This plane is a beast. I take it the retracts are home made, also which kit or plans is it?

Idigbo

Cheers folks, its good to be different! Zulu, the model was scratch built by Rick Stevens and I managed to prize it away from him. I had a few issues with it, ailerons falling off (luckily they fell off whilst I was trying to get the junk motor to run, so no biggy. Lost an elevator linkage in flight which was interesting, at which point I worked through the model replacing all linkages, tail retract but never did get to replace the motor [] The retracts are home made. Designed and originally built by Rick they follow closely the full size. The retract rebuild was easy enough since I had the bits to copy. This is the colour scheme I like, just love the writing on the sides. I presume the plastic model has taken some artistic licence and added the writing on both sides, or was it that way? Also, what does the writing say? Presumably some sort of presentation aircraft perhaps?

Ian.