1/6 Scale Yak 9D from 3 views - Page 2 - RC Groups
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Mar 14, 2012, 05:25 PM
Crazy Cessna Owner
Robbie d's Avatar
I should make up some decals, etc for my PO-2. Flies like a champ on a tiny CD-rom motor
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Mar 14, 2012, 08:10 PM
Scale Builder
Excellent choice of subjects Mr. Fawcett! From all accounts the Yak designs make very good models. The highly tapered wing makes some folks nervous but it has proven itself to be very docile despite the narrow tips. I have two Yak-11 designs currently flying, a 66 inch span sport version for racing and an 82" inch span giant scale version, and both builder's are extremely happy with the flight characteristics. The bigger one uses the scale ClarkYH airfoil with 3 degrees of wash out and is, according to the builder, the best flying warbird model he has flown. The smaller one is modeled after the Reno racer "Czech Mate", uses a SD6060 airfoil with the same 3 degrees of wash out and is a really nice flying model with no tendency to snap out, even in very high G turns. I have not doubt that your Yak will be a fine performer as well and I definitely look forward to seeing the finished product.

Here is the 82 inch span version built by a customer in Germany.

And the 66" span racer built by my friend Rober Vogel.

Mar 14, 2012, 11:12 PM
RFC Cadet
Guy Fawcett's Avatar

Progress 14-Mar-12

Well today I refined structural details on the fuselage drawing not much to show there

But I also started shaping the elevator and stab. Also managed to make the first piece of the fuselage.

The PO 2 sounds great.


Very Pretty looking planes.
Mar 15, 2012, 04:02 PM
a.k.a Maltone
Pat Lynch's Avatar
It is looking to be a great build Guy - I have always loved the freedom that comes with building from a 3-view. Did you make 'proper' drawings of the whole model or designing the structure as you go? Many folk, including myself, enjoy seeing how others approach the design/build task.
I hope you keep it up
Pat (also with a couple of unfinished models........)
Mar 15, 2012, 07:37 PM
RFC Cadet
Guy Fawcett's Avatar

Design Philosphy

Hi Pat

What I try to do is create the best set of scale three views that I can. Once the scale drawing is complete I choose the scale of model I want to build and begin adding model structure. When possible I use full scale indicators for locating the models underlying bones. A row of rivets or panel joints indicate a rib or stringer location.

The model structure drawing and templates are added as I go and find a need for them.

In the case of the Yak I drew the rudder/fin assembly started construction and while waiting for glue to set ( I use carpenters glue) I started drawing the elevator/stab assembly and so on until I have an airplane.
Mar 15, 2012, 08:52 PM
RFC Cadet
Guy Fawcett's Avatar

Progress 15-Mar-12

Well I started to frame up the fuselage.
Mar 17, 2012, 04:27 PM
Registered User
Mike Smart's Avatar
Originally Posted by Guy Fawcett

Wing Area : 728 sq.in.
Wing Span : 64"
Length : 56'

Proposed Moto r: Axi 5320/34,
Battery : A123 6 series x 2 parallel cells;
Prop : Vario 16D 3 blade 19.9"

Sound: Model Solutions (now Model Sound Inc.), SFX5.3 and 4" speaker.
Thats a big motor for a 64" span model

Mar 17, 2012, 04:43 PM
eye4wings's Avatar
A big motor, yes, but there is the weight of a sound system to carry as well Mike.

I'm using an Axi 4120 for my 60" La-5 which I surprised myself by deciding to repair about the time this thread started. ( I crashed it on its second flight three years ago - never got to find out if the automatic wing slats worked as I still had them taped shut).

I'm coming along for the ride so I can compare the two.

Do you have a target weight for yours Guy?
Mar 17, 2012, 05:08 PM
RFC Cadet
Guy Fawcett's Avatar

Motor choice

Hi Mike

The motor was chosen for swinging the 19.9" 3 bladed close to scale size prop with sufficient rpm and pitch to produce the speed I want. Notice that the 6s2p pack is below normal size for the motor.

Hi eye4wings

Hoped for target weight is between 9 and 10 LBS. Gets windy here in Alberta and all my biplanes get too easily grounded
Mar 17, 2012, 05:25 PM
eye4wings's Avatar
Thanks Guy. The only problem with more weight is that the wing loading and drag go up, but granted it does help a model punch through windy conditions with a better semblance of scale performance than just trying to do it with power alone.

Just checked my motor/prop and it is Axi 4130/16 with 20"x10"x3 not 4120 as stated before. Sorry about that.
I normally overprop my motors but compensate by dropping the cell count so as to balance the current draw - hence the larger pitch than normal. I was running 4S at the time of my crash but I may just try it on 5S if the current draw allows.
Mar 17, 2012, 05:43 PM
Registered User

Klimov Engine Rotation

Hi Guy

I was in the Museum of Flight last year and saw the original Yak 9U they have. Of interest to me was the reverse rotation of the engine.

I had seen new build Allison powered Yak 3's and 9's and the Klimov rotation was a surprise. Ramoser does left and right blades so it may be an option for you.

You may remember my dad Brent's 56" Enya 45 powered Yak 3 with retracts and flaps. It was an excellent flyer and turned heads in the late 60's-early 70's. It was published in MAN.

Dad built a 70" version for his winter trips to Phoenix in the late 90's. Flew even better at that size. He used it for warbird racing until it was midaired.

Dick Baum from Moose Jaw designed and built an even larger Yak 3 which he still flys.

I will try and rustle up some pictures.

Dad passed away peacefully in Yorkton last month.

Best regards
Mar 17, 2012, 07:46 PM
RFC Cadet
Guy Fawcett's Avatar
Hi Garry

We really should keep in better touch (mostly my fault I guess). Very sorry to hear of your Dads passing and I do remember watching his Yak 3 flying at the 73 Yorkton Nationals even have some B&W photos somewhere around here.

Thanks for the info on the Klimov. Even with looking at all the pictures I hadn't noticed that and now another quandary, to counter rotate or not to counter rotate. That is the problem. Good thing is I haven't ordered the prop yet.
Mar 18, 2012, 04:06 AM
eye4wings's Avatar
From the few pictures I have the Yak9 rotation seems to be clockwise viewed from the front - but in view of the cost of props at this size my own choice is to go with the cheapest available. Unless you fly with a load of Anoraks your bank balance is the most likely to notice the difference.

Making up your own 3-blade from a couple of 2-blade props cheapens it considerably of course - and I was grateful of having a spare blade left over when I crashed. The prop was the first thing repaired.
Mar 18, 2012, 11:44 AM
Registered User
vonJaerschky's Avatar
Looking good, Guy! Interesting to see you move on to WW2 models. You just want to chase my 109, don't you!?

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