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Need help asap for firewall doweling/re-enforcement

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Need help asap for firewall doweling/re-enforcement

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Old 08-22-2008, 07:11 PM
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ErikElvis
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Default Need help asap for firewall doweling/re-enforcement

Hey guys,

Just putting together the sundowner 50 and ppunched out all of the pre installed blind nuts. A few took some of the inner firewall with them. Now I have either 3/8 dowels or 5/16. Does it matter what size I use to plug the holes with? Also it is ok to use elmers wood glue for the dowels correct? Now I also have some light 1.5oz fiberglass cloth I could lay on the inside of the firewall. would this help? The engine going on this plane is the OS 91 surpass... a lil big I know...

Please help with your tips and thanks,

Erik
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Old 08-22-2008, 09:14 PM
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Default RE: Need help asap for firewall doweling/re-enforcement

I would grind or shave the dowel so it just fits tightly into the existing hole size, I wouldn't make the hole fit the plug. Make sure the plugs are flush on both side when done. Use 15 minute epoxy and leave it alone for a few hours. The inside fire wall, engine box and wing hanger area are real dry of glue, so out in the sunlight I drip in to the joints some thin CA to start the wicking action and than chase it with thick CA as to not make all the balsa or plywood solid glue and heavy. Have acetone and paper towel ready for leaks and spills. Before you CA, iron down all the covering so if the CA gets through the sheeting it won’t fill the wrinkles. “Think light", keep the glues and epoxies to the minimum. Lastly locate and drill the new holes for the blind nuts.
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Old 08-22-2008, 09:40 PM
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Default RE: Need help asap for firewall doweling/re-enforcement

I'm surprised you don't have to move the firewall back?
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Old 08-23-2008, 12:33 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

Well I fit the dowels and sanded them down on the front. I then slapped a coat of 30min epoxy to the front. The rear of the dowels is what looks crappy. There are some chunks of the ply missing. Not horrible though. Do you think I should fit the blind nuts and engine then put a layer of 1.5oz glass to the inside over the blind nuts? I could prob drill small holes through the blind nut and then the fiberglass so the bolt easily passes through.
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Old 08-23-2008, 01:36 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

Ok another question. How will I know if the engine mounts are in the right place to drill them? For the top and bottom marks I can extend the lines but how about the left and right lines?
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Old 08-23-2008, 08:15 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

Draw a horizontal line across the centre of the original hole locations, then re-drill each hole 3.1mm further out. This will overlap the originals, so do small pilot holes first to avoid a wandering drill bit. This, using the supplied mount, was perfect for my OS 91FS and has been no problem.

Cam
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Old 08-23-2008, 01:26 PM
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Default RE: Need help asap for firewall doweling/re-enforcement

There you are Cam. I did fit the motor and cut the cowl but mine is no where near as nice as yours. Im hoping a lil time and some sandpaper will make the holes bearable. I pulled a red eye plane building night last night. And am still no where near done. [:@]
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Old 08-24-2008, 01:05 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

OK Im having a hard time with the throttle. I cant seem to get it so it doesnt bind somewhere. Any probs with yours?
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Old 08-26-2008, 02:56 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

No. Remember the pushrod moves side-to-side with the barrel opening/closing. You should have a diagonal slot in the firewall to follow the throttle arm. Let me know if no luck and I'll have a closer look at mine.

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Old 08-26-2008, 12:40 PM
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Default RE: Need help asap for firewall doweling/re-enforcement

I ended up putting the throttle line way out on the edge. It went through the tri stock inside. But it finally isnt binding. The prob is there isnt much room for that wire to move since the throttle arm is so close to the motor box. If it were farther out the wire would give a lil. Well seems ok now. I think Im done working on it for a bit. Have the tail, landing gear, and a lil cowl cleanup to do. Im going to see how it balances with everything in the right spot. Then from there I might add a couple strips of balsa behind the wing and velcro the battery back there. Let me know how your flights are goin cam.
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Old 08-28-2008, 04:34 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

Hi EE,

I cut through the fuz behind the wing underneath - there's a "hole" there anyway. Put a couple of ply strips across the fuz - glued to stringers - and shoehorned in a 3700mAH 4-cell NiMH pack, a pretty big pack. Re-covered hole. Balance was perfect with that setup.

Will take her out on Sunday weather permitting, and report back.

Cam
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Old 08-30-2008, 12:22 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

I plan on running a 2300mah 6V pack. How fast do you think your goin in your downer? I was maybe going 70 tops level. And thats pushing it. In my short experience with rc I really dont like a plane that flies doggish at half throttle. I want to fly comfortably at half to 3/4 throttle with the full throttle burst for fun. Im thinkin with the stumpier body, slimmer wings, and less weight the 91 should pull this thing around nicely. let me know how sunday goes.
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Old 08-31-2008, 06:04 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

In a word, rainy...[:@] Will let you know when things clear up - last day of our winter today so I live in hope. I've got a 2 week holiday looming, so if all else fails I'll get it out for a good fly then.

Don't worry about it being sus at 1/2 throttle - it was cruising along nicely. Another clubmate apparently has one with an OS .55(?) 2st and those watching my test flights said mine was WAY faster, and that was running rich and on a conservative prop. Leaned out with a bit more pitch on the prop, it's gonna be a hoot.

Cam
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Old 08-31-2008, 03:16 PM
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Default RE: Need help asap for firewall doweling/re-enforcement

Well if you have any more bad weather I might just catch up to you as far as flights go. Hope to finish and balance tonight. Just need to clean up the cowl a lil, throw in the servos for the elevator and rudder, and hook up the receiver. Oh and retune the engine. I think I was at 2.5 turns out on the high speed. Is the stock tank lasting you a bit? On the minnow I know I could be up well over ten minutes on a tank. Cant remember the size though. And that was near full throttle all the time.
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Old 09-01-2008, 05:13 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

Not sure about tank. I set my timer for 12 mins and had plenty left with 2/3-plus throttle most of the flight after landing at about 10 mins. I'll run it dry for you next flight....

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Old 09-04-2008, 01:00 AM
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Default RE: Need help asap for firewall doweling/re-enforcement

What prop you running? Im gonna start with a 13x9. I also have a 12x11 laying around. Just waiting for the tru-turn spinner. I went with a 2 1/4 ultimate to give a smaller sleeker look. Ive slacked due to work and drinking but it better get up this weekend.[8D]
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Old 09-08-2008, 07:25 PM
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Default RE: Need help asap for firewall doweling/re-enforcement

Well I maidened her today. Flew great. Only got one flight though. My fill line was split and dumped a pond of fuel into the fuse and soaked my foam. I added about 2oz of lead to the tail and left everything else where it was suppose to be. It dropped in fast but remained responsive. It wasnt till I was almost on the ground I noticed it dead sticked. Now back to cleaning the fuel and fixing the line problem...
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