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Extreme Flight 87" Yak 54 - Build & Fly

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Extreme Flight 87" Yak 54 - Build & Fly

Old 05-12-2005, 03:48 PM
  #4826  
morecashthansense
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Hi all
a couple of pics of the blinged up canopy...

came out a lot better than I thought it would.

Plus a little redesign on a messed up rudder instalation after a few trys this works very well no slack untill on the max deflection...
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Old 05-12-2005, 04:24 PM
  #4827  
747drvr
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly


ORIGINAL: NE0

I'm thinking of using 8-32 nylon bolts to hold my cowl on . I'll also just drill/tap/harden the mounting blocks. Any comments ? I'm thinking that the 8-32's have a larger diameter and won't have as much of a tendancy to enlarge the hole under vibration . Also , the nylon in the tapped holes should have enough friction to resist backing out .

Marc
That's what I'm doing. Big 8/32 nylon bolts through black grommets into blind nuts. Also added an extra mounting block at the 12-o'clock position. I think it's quite solid now and the nylon bolts will not eat the cowl. Has always worked before

Tom
Hi Guys,

Just got the cowl mounted with the nylon bolts . I also used the plywood patches recommended by Dick . I didn't use grommets and agree with Dicks's approach , that the cowl should be hard and not soft mounted . The holes in the cowl are a tight fit to the bolts , so as long as the bolts stay tight there should be no movement . I'm also thinking that nylon threaded into wood is a slightly tight fit and should prevent the bolts from backing out with vibration . I also agree with Tom that the nylon bolts will not eat the cowl . Maybe the other way around ! We'll see !

Marc
Old 05-12-2005, 04:29 PM
  #4828  
747drvr
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Question regarding cutting the cowl. I've noticed that most people have opened up the cowl to expose the cylinder head. It appears to me that only a small area is necessary to clear the plug and ignition wire. Is it needed for cooling ?Any comments ?

Marc
Old 05-12-2005, 04:30 PM
  #4829  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Nice canopy -adds a lot to overall look
Old 05-12-2005, 05:46 PM
  #4830  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I think they look ok. You need a big 5\16'' hole in the fiberglass for each one. I like Dick's idea of reinforcing the inside with ply. If the holes start to get bigger I will do that. For now they are working as advertised. I did not use the screws that came with them. Instead 4-40 button heads and blind nuts, and a little blue loctite.

Marc you need to open the cowl for cooling.

Dave



ORIGINAL: jrjohn


ORIGINAL: Dave763

I am using the PSP cowl binders. They work great. 20 flights no problems. Just be sure the hole is the right size, so they fit tight.
Dave, any chance of seeing a couple pics of your cowl with the cowl binders. I have a feeling the work really well, I'm just wondering about the Ugly factor. I ordered two sets today.

John
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Old 05-12-2005, 05:53 PM
  #4831  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Man I love this plane. Havn't flown anything else since I got it.
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Old 05-12-2005, 06:53 PM
  #4832  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Question regarding cutting the cowl. I've noticed that most people have opened up the cowl to expose the cylinder head. It appears to me that only a small area is necessary to clear the plug and ignition wire. Is it needed for cooling ?Any comments ?

Marc
Absolutely a reason... to obtain adequate exit venting of ambient air around engine (cooling). In order to keep your engine running cool, you've got to move the hot air surrounding it in the cowl by maintaining a constant airflow, almost a vaccuum. Rule of thumb is that you need to have an opening in your cowl for the air to exit OUT that is at least TWICE as large as any openings where air is coming IN to the cowl. In other words a 2:1 ratio of exit opening/s to entrance opening/s will produce the proper suction/venturi effect to keep the air moving through the cowl, and not just rolling around IN the cowl.

With a larger radial cowl, you have a lot of opening in the front that is taking in air. If you don't cut out enough of the cowl, the air gets trapped in there and becomes stagnant hot air (much like that which comes out of most RC modellers mouths ).

So, you can calculate the actual area if you want, but I just "eyeball" it to get it close. Just make sure you have somewhere for all that hot air to go to get out of the cowl quickly. Especially if you have an in-cowl muffler.

Tom
Old 05-12-2005, 06:59 PM
  #4833  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Dave, thanks for the pictures of the cowl binders, they look great, I'm glad I ordered two sets. I talked to the owner of the company today, he told me if the inside half of the cowl binder is too thick we can sand up to a 1/2 of the thickness down. I might sand a little off mine so I will have the same fit as I have now.

For you guys using the rubber gromets, It's only a matter of time, and you will only realize your mistake in retrospect. I would not have noticed my screws had eaten through the gromet and into the cowl had I not taken the cowl off to fix the firewall that I was told could be a problem. I had less than 10 flights.

I love the plane, there is nothing like it.

John
Old 05-12-2005, 07:21 PM
  #4834  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I have tried the rubber grommet thing on other planes, works till the fiberglass eats through the grommet. Maybe there is a way to blind mount it, with a cowl ring inside. I have done this on my 36% Katana. Looks neat with no screws showing.
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Old 05-12-2005, 11:26 PM
  #4835  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly


ORIGINAL: Dave763

I have tried the rubber grommet thing on other planes, works till the fiberglass eats through the grommet. Maybe there is a way to blind mount it, with a cowl ring inside. I have done this on my 36% Katana. Looks neat with no screws showing.
Jeff Williams has a cowl ring in his Yak, perhaps he will post a pic.
Old 05-13-2005, 04:36 AM
  #4836  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly


ORIGINAL: Dave763

I have tried the rubber grommet thing on other planes, works till the fiberglass eats through the grommet. Maybe there is a way to blind mount it, with a cowl ring inside. I have done this on my 36% Katana. Looks neat with no screws showing.
That is actually a very, very GOOD idea!!!! It would also make the cowl a little less flimsy and less likely to crack. I can't remember if it was Carden or ohio RC planes that used that technique, but when I used to build proffesionally, I remember them and the only thing I didn't like about it was installing and removing them, but they did look nice. You should call Chris about it to ponder...
Old 05-13-2005, 08:13 AM
  #4837  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I have tried the rubber grommet thing on other planes, works till the fiberglass eats through the grommet. Maybe there is a way to blind mount it, with a cowl ring inside. I have done this on my 36% Katana. Looks neat with no screws showing.
How do you get no screws showing???? What holds it on?
Old 05-13-2005, 08:47 AM
  #4838  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Personally I do not like any cowl ring setups
tho they don't show bolts - all the rest of the setup is either awkward or prone to failure OR you can't detect bolts coming out till they FALLout
Easy set?
a 1/4" thick strip on each side of F1- inset 1/4"

1/4" blocks /plates solidly attached to cowl --which match these plate positions
drill thru - add blind nuts and countersink for skt bolt heads
This also self aligns each time cowl is mounted
The ARF guys don't do this -- as it simply is additional work step in construction
Th nice part is instant access to all mounting bolts which are also flush with cowl surface.
the shock isolation technique is in my opinion not as smooth looking and is far more prone to failure over time
Just my own thoughts -------
Old 05-13-2005, 08:50 AM
  #4839  
Maudib
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Neo,

It's like the challenger I built... you use front former as a template to cut a ring of ply.

The ring is temp mounted to the former and the cowl fitted and tacked.

The ring is then permanently epoxied to the cowl and reinforced.

Then the screws go in from the front of the cowl to reach back and screw the cowl ring to the front former.

It makes for a decent setup, though maybe a tad heavier and a few steps more work.

Here is a pic of the wooden cowl I made for the C3... The ring shown is the "cowl ring" and was screwed (or blindnutted to the F1 former).... This pic shows it before I trimmed the excess wood to the ring....

On an ARF, there will be some inset usually as the cowl fits back further than the F1 former... On the Yak we'4re talking maybe only 1/4"-1/2" inset.

J. David

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Old 05-13-2005, 09:02 AM
  #4840  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Nice work on the wood cowl
I usually plank build this type stuff -or use lost foam /glass technique
Old 05-13-2005, 09:10 AM
  #4841  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Over 100 flights on my cowl ring setup. Dick try some loctite on those screws that keep coming loose on your planes.LOL

I did mine the same way Maudib has explained. One difference is I installed the top screws with the hatch off through the front former and into the cowl ring.


Dave
Old 05-13-2005, 09:23 AM
  #4842  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

If you like -it is the best setup for you!
Old 05-13-2005, 11:08 AM
  #4843  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Of all the contributors to this thread i'm on the low end of building skill sets but i'll pass on what has worked for me re: the cowl. First I sanded and prepared the cowl area around the mounting holes and tried to remove as much of the release agent as possible. After this I epoxied CA hinges over the hole areas (inside the cowl) and applied another coat after the initial coat dried. Then after this dried I simply applied clear RTV "seal" over that to form a soft, gripping type area for the cowl tabs to "hold ont to" .

Next I cleared the holes, used a 4x40 bolt with an alum. washer mounted to a soft, black plumbing fawcet washer and used blue locktite. It's very simple and holds like the devil. The mount is not dependent on the holes in the cowl but rather the grip of the rubber washer to the cowl and the RTV to the cowl tabs and the 4x40 bolt to the blind nuts. I found that replacing the 4x40 bolts (included with the kit) with new 4x40 bolts provided a much tighter fit & grip.

The cowl has been a non issue.
Old 05-13-2005, 11:25 AM
  #4844  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

good setup -- you removed the "shake" from the system and used a flexible tight grip
If I was to really redo mine - Iwould add blocks to back surface with countersink for flush bolt mount -simply slicker look but the present mod holds securely with no deformation from bolts and no loosening
Old 05-13-2005, 01:12 PM
  #4845  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Does anyone have a picture of how they cut their cowling for a slimline pitts muffler ?
Old 05-13-2005, 06:18 PM
  #4846  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

I going to search but just in case does anyone have pics of how the mounted thier Rx and batteries. I'm trying to figure the best way to secure them to the plane. THanks
Old 05-13-2005, 06:28 PM
  #4847  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

All depends on how you're balancing. With a stock muffler and the gas tank on the wing tube/CG... here's where my battery is for now. I made a tray with 2 positions available with velcro straps. The tray is glued to the balsa pipe tunnel, just in front of the tank. (right where the cowl and canopy meet.)

Old 05-13-2005, 10:16 PM
  #4848  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly


ORIGINAL: CHassan

I going to search but just in case does anyone have pics of how the mounted thier Rx and batteries. I'm trying to figure the best way to secure them to the plane. THanks


ORIGINAL: flyingcrazy

Does anyone have a picture of how they cut their cowling for a slimline pitts muffler ?




Old 05-13-2005, 10:49 PM
  #4849  
flyingcrazy
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

Thanks for the picture !!!!!!!!! Very nice set up it LOOKS-A-GOOD ! Mine is getting their not much left to do got to get a recever. Money is tight because I just bought a 2.6 comp. YAK ready to fly! IM IN YAK HEAVEN .
ORIGINAL: BBriBro


ORIGINAL: CHassan

I going to search but just in case does anyone have pics of how the mounted thier Rx and batteries. I'm trying to figure the best way to secure them to the plane. THanks


ORIGINAL: flyingcrazy

Does anyone have a picture of how they cut their cowling for a slimline pitts muffler ?




Old 05-14-2005, 03:18 AM
  #4850  
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Default RE: Extreme Flight 87" Yak 54 - Build & Fly

[]sometimes it works sometimes it doesnt. my computer that is.

Thanks NEO and BBriBro. I figured out a way to get stuff stuck on. Velcro was the order of the day. That, epoxy and some 3/4X1/4 basswood.

I need to cut my cowling, buy one more extension (that will be the 20th trip to the LHS since I told my wife I had everything I need), clean up the wires, figure out how to get everything programed, and buy some gas and things will be getting interesting.

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