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Extreme Flight 87" Yak 54 - Build & Fly

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Extreme Flight 87" Yak 54 - Build & Fly

Old 05-09-2005, 09:18 PM
  #4776  
BBriBro
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly


ORIGINAL: jrjohn

The guy that came foreword with this problem probably saved my plane

thank you

John
it was actually brought up a while ago, but not discussed since he was the only one. Mine broke more than 2 months ago (shortly after I started flying it) I don't think I would have ever lost the engine though, since it has a large washer behind the firewall essentially holding all the plys sandwiched together. In my case there were no failed glue joints either by me or from the factory that built the airplane, so I don't know what to say, unless Chinese plywood isn't very good, like weak Chinese hardware.
Old 05-09-2005, 09:21 PM
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

OK let's get specific - here is a picture of mine
Note that I added a piece of 1/4"x1/2" ply behind the firewall to better support the ZDZ lower mounting bolts .(which are located in a different place than that of the DA) Doing this ,effectively added a return (L shape), to this bottom edge
Is this the location where your firewall came apart?
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Old 05-09-2005, 09:36 PM
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Dick, your lower bolts a up higher and more to the outside of the firewall, I can see why you setup would be stronger. If you look where the lower DA mount holes are, you can see why there is enough leverage to crack the firewall.

Mine firewall is not de-laminated, it's actually cracking straight through imediatly below the tri-stock. I had to wiggle the engine to see it. I'll pull the cowl off tomorrow and take pictures.

john
Old 05-09-2005, 09:38 PM
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Dick, can i see a picture of the back side of your firewall where you added the 1/4 x1/2 ply. I believe this is what I'm planning on doing.

John
Old 05-09-2005, 10:03 PM
  #4780  
jrjohn
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Dick, the piece that you added to the back of the firewall. Would the measurments be
5 7/8 x 1 1/8 x 1/4 thick?? (with a little jog to go around the side wall) If so, I think that will fix the problem. Wish I had added it before glueing in the tristock.

john
Old 05-09-2005, 10:38 PM
  #4781  
fancman
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I know what you mean about the Chineese plywood. I had a Patty Wagstaff that I did a nose over with and the area where the engine bolts went into the firewall pushed right through the wood. It sort of shattered and delaminated. The wood was nothing like the aircraft grade plywood you would expect in this area. On that airplane I ground out all the tri stock on the front of the firewall and glued in 1/8" (real) plywood to the front of what was left of the 1'4" junk plywood that was used in the kit.

The Yak is a great flying plane and I'm happy if my post has alerted anyone of the possible problem. That was my intent. Thanks
Old 05-09-2005, 11:05 PM
  #4782  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Here is a better shot of what I used --and it was simply because I felt the ZDZ holes were too close to the cutout.
The wood is aprox 1" high -full width and is aircraft grade -note the laminations .
I only glanced at the DA template -as it was not applicable to me .
I also used 10x32 blind nuts for the thru bolts in the rock hard maple supports .
I personally prefer this to metal mounts as it widens the footprint from the motor flange. Those blocks are 1"x1/2" end grain and are as rigid as any metal support .
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Old 05-09-2005, 11:30 PM
  #4783  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Dick, thats exactly what I'm going to do. How do I get the epoxy to stick to an area that was previously coated with epoxy. (the tri-stock area) when I put the tri-stock back in. Doesn't epoxy work best when it soaks into the wood? This is a critical area and now I'm concerned about the tri-stock joints holding.

john
Old 05-10-2005, 06:20 AM
  #4784  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly


ORIGINAL: jrjohn

Wish I had added it before glueing in the tristock.

john
Yes! , that would make it easier and cleaner, than fixing it afterwards, oh well. One day it might need a new firewall, and then it will be neat and clean.
Old 05-10-2005, 06:27 AM
  #4785  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

JRJohn,

Sand the existing epoxy with a medium coarse sandpaper to remove the "slick surface"... epoxy with then adhere to itself as well as bare wood.

As an extra "umph" you could drill a few 1/8" holes through the front and into the extra plate and glue some 1/8" dowels to add additional glue surface.

ORIGINAL: jrjohn

Dick, thats exactly what I'm going to do. How do I get the epoxy to stick to an area that was previously coated with epoxy. (the tri-stock area) when I put the tri-stock back in. Doesn't epoxy work best when it soaks into the wood? This is a critical area and now I'm concerned about the tri-stock joints holding.

john
Old 05-10-2005, 08:27 AM
  #4786  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Dick, how much did you say your plane weighed??????????? I seem to remember you said you would be in the 15 pound range, but with a ZDZ, tuned pipe, choke servo, Nimh's, aluminum gear, and a heavily painted canopy, I would say you will probably have the heaviest Yak out there????
Old 05-10-2005, 09:08 AM
  #4787  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

David, first of all it's great to have you back on the thread. I hope your doing well.

I just talked o a buddy of mine, he hasn't completed his plane yet, however during the building process he suspected this part of the firewall would be a problem and added a piece of alluminum angle stock. Bolted the bottom engine mount screws right through it. I'm considering this avenue, but not sure yet

John
Old 05-10-2005, 09:08 AM
  #4788  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

wrongo--
It weighs exactly 15.25 lbs
First -the al gear is lighter --also-no wheel pants-smaller wheels - lighter, scale tail wheel I did from carbon rod and ABS block .
the canopy paint is a few grams at best.
One elevator servo (tho both elevator and rudder servos are 8611s-not light)
The ZDZ50 and the DA50 weigh to the ounce -same weight - I have had both at the same time in the shop.That's a fact
My scales are calibrated from my triple beam Ohaus scales -so thats what it is
Oh yes -it is a bit nose heavy relative to recommended CG-but look at the pics - It does the 3D stuff easily -and knife edges with essentially no elevator corrections .
I really like it!
Easily one of the best kit aerobatic setups I have flown.
Old 05-10-2005, 12:27 PM
  #4789  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

How I can put a picture in the forum.

Can Help me[&o]
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Old 05-10-2005, 12:29 PM
  #4790  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I do

Is my Carden Cuda

The saturday was the first fly.

Awesome plane

DA 50

JR 8611 on all

Fly sweet

The nex saturday I hope fly my YAK
Old 05-10-2005, 02:16 PM
  #4791  
coche
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

your cuda looks nice Carlos! you are going to love the Yak!
Old 05-10-2005, 04:12 PM
  #4792  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

ORIGINAL: dick Hanson

wrongo--
It weighs exactly 15.25 lbs
First -the al gear is lighter --also-no wheel pants-smaller wheels - lighter, scale tail wheel I did from carbon rod and ABS block .
the canopy paint is a few grams at best.
One elevator servo (tho both elevator and rudder servos are 8611s-not light)
The ZDZ50 and the DA50 weigh to the ounce -same weight - I have had both at the same time in the shop.That's a fact
My scales are calibrated from my triple beam Ohaus scales -so thats what it is
Oh yes -it is a bit nose heavy relative to recommended CG-but look at the pics - It does the 3D stuff easily -and knife edges with essentially no elevator corrections .
I really like it!
Easily one of the best kit aerobatic setups I have flown.
Hey Dick

Did you make your own landing gear or is it off the shelf?
TIA
Old 05-10-2005, 04:22 PM
  #4793  
Richard D Bahmann aka/Wrongway
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

[Rdb127,
Honestly, you have a month and a half, at least before your plane gets here to build up funds to get a larger gas engine and sell the Moki. Not only will you have balance issues but you will probably not like the performance. If that engine can turn, say, a 22X8 at about 6500, it might hover, but a 20 inch prop doesn't have much blade sticking out past that fat cowl and it will diminish thrust quite a bit... ]

Bodyworks,

Hey thanks for the advise. I cut loose today and ordered a DA-50 from Don's Hobbies. Still have them at old price saving 45 bucks. Will try to put a couple of tanks thru her on the test stand so all will be jam up and jelly tight for the first flight on the second [production] run EF-YAK.
I guess I will see if I can find someone who wants the Moki 2.1, I did get it to turn a Zinger 20X10 at 7000 but it won't be the same punch as the DA. If you know anyone looking for a 2.1 with around 2 gal thru with Bisson Pitts, I can even throw in a prop and mounting backplate have them PM me.

Richard -all I need now is a 87' EF Yak.. Trailer..Froemco...switches...sunny day.....
Old 05-10-2005, 04:38 PM
  #4794  
Richard D Bahmann aka/Wrongway
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Wanted to add to the last post for you guys interested, Don's hobbies says they are about 3 weeks behind on DA-50 orders.[X(]
Old 05-10-2005, 04:42 PM
  #4795  
rmh
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Yes -I made the gear and tailwheel assy, etc..
Iwanted to make a more scale look -and it was very easy .
Old 05-10-2005, 09:19 PM
  #4796  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

More flying today I'm starting to get really comfortable with it. Almost got two gallons thru it now. The 32:1 sure messes up the bottom. Yuk.
My firewall was coming loose at the bottom. I posted pics of the repair back a few pages. This thread is so long its hard to find anything unless its bookmarked.

Here is the post http://www.rcuniverse.com/forum/fb.asp?m=2898150
Old 05-10-2005, 11:07 PM
  #4797  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Help, I ran out of gas and my plane went down in a drain ditch. Up to the wings submerged in water. Minor damage, but I need to know what the covering on the bottom is. I am trying to cover with monocoat and it is not sticking well. Please, if you know what it is, let me know. I fly IMAC this weekend in Oregon and desperately need to get my plane ready to be in the air. Thank you...

ten pillows[sm=drowning.gif][sm=confused.gif]
Old 05-10-2005, 11:15 PM
  #4798  
flyingcrazy
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I had to recover most of my fuse I used utralcoat it did stick to the other. Hope this helps.
ORIGINAL: ten pillows

Help, I ran out of gas and my plane went down in a drain ditch. Up to the wings submerged in water. Minor damage, but I need to know what the covering on the bottom is. I am trying to cover with monocoat and it is not sticking well. Please, if you know what it is, let me know. I fly IMAC this weekend in Oregon and desperately need to get my plane ready to be in the air. Thank you...

ten pillows[sm=drowning.gif][sm=confused.gif]
Old 05-10-2005, 11:21 PM
  #4799  
ten pillows
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Thanks Rodney,

I will have to get some tomorrow. I appreciate the quick response.

ten pillows
Old 05-10-2005, 11:22 PM
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wgeffon
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

The plane is covered in Oracover. Thats the same stuff as Ultracote.
They just use a different name for it over there.

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