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Firewall removal

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Old 12-27-2007, 10:37 PM
  #1
snacker
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Default Firewall removal

I've recently decided I would like to put a bigger fuel tank in my Sig SR Kadet. The only way to do this I can see is removing the firewall. Does anyone know the best way to do this and what tools should be used? Also what is the best way to re-attach it after I'm done. Any recommendations on the largest or best tank to install?

Thanks for any suggestions.
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Old 12-27-2007, 11:21 PM
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Default RE: Firewall removal

alot of people seem to just fly them into the ground, most of the time that will free them right up
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Old 12-27-2007, 11:42 PM
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Default RE: Firewall removal

If you can, post a picture or two of your firewall and the tank placement area.
If im understanding you correctly, you want to remove and reattach the firewall, moving it forward on the fuselage,
making room to install a larger fuel tank.

Have you checked on a wider/taller tank of the same length? You may be able to stuff a bigger tank in without the need,
to lengthen the tank compartment.

If you cant supply a picture,take some measurements of the tank area,so we have something to work with.

I replaced a 8oz.tank with a 12 oz. on my Great Planes cap 232 without having to alter the build.
There are several types of tanks available, there may be one that will install without the need to alter your firewall.
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Old 12-27-2007, 11:51 PM
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Default RE: Firewall removal

The tank is round with a flat side on each side if that makes sense. The wood behind the firewall is specifically cut to fit this tank which is why I only think it can be done by removing the firewall. I hope this pic helps.

Thanks clouddancer.
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Old 12-28-2007, 12:06 AM
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Default RE: Firewall removal

Heres a link that may help, i noticed several sizes of round or cylinder type tanks.

I also noticed on the 10oz. and 12oz. sizes, the square tanks are shorter than the round tanks of equal volume.

I think a short square tank might just work better, thats what i used on my cap 232.

Scroll down on this link and read about the Rectangular Flextank, that may be a possiblity as well.


http://www.sullivanproducts.com/Fueltanks1Content.htm
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Old 12-28-2007, 12:18 AM
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Default RE: Firewall removal

Snacker - I'm putting a Kadet Sr. ARF together right now. I see no need to remove the firewall. To put a larger tank in, I would use my Dremel tool with the flex shaft to get in and modify the factory tank cutout. No problem going in through the cabin area with this. Tower Hobbies site gives dimensions of most tanks they carry. If you don't have the Dremel tool just get a small rough cut file. Slower, but it will get the job done too.
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Old 12-28-2007, 12:19 AM
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Default RE: Firewall removal


Quote:
ORIGINAL: dragnbye

alot of people seem to just fly them into the ground, most of the time that will free them right up
That is funny Though not very helpful in solving the problem.
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Old 12-28-2007, 12:41 AM
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Default RE: Firewall removal

Thanks for the link clouddancer. One of those tanks might work with some slight modifications. I'd like to at least put a twelve ounce tank in. I'm afraid of eight ounces not giving me much flying time with the OS 91 I'm putting on. What do you think?

Flylow, I just got a dremel stylus for Christmas but there's no flexshaft included. I don't think I can fit the dremel inside the plane. Is there a flex shaft for the stylus?
Thanks.
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Old 12-28-2007, 12:55 AM
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Default RE: Firewall removal

Did the plane call for a 60 or 90 size engine?

If that engine is called for there should be room in the plane for a 12 to 14 oz. tank, which is about what you would want
for those size engines.

If you are putting a larger engine and tank on then called for, that may explain a tank not fitting.

If this is the case, your cg will change dramatically as well.
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Old 12-28-2007, 01:43 AM
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Default RE: Firewall removal

There's plenty of room for that size tank, the inside just needs to modified do to the factory installed wood supports for an eight ounce tank which are hard to get to. The plane is recommended I believe up to a 60 size engine however I believe the OS 91 is the same size/dimensions as the 60.

I have flown this setup before, I just need some helpful hints in making my own modifictions in the least painful way possible.

Thanks again.
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Old 12-28-2007, 06:32 AM
  #11
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Default RE: Firewall removal


Quote:
ORIGINAL: dragnbye

alot of people seem to just fly them into the ground, most of the time that will free them right up

LOL [sm=lol.gif]
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Old 12-28-2007, 06:56 AM
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Default RE: Firewall removal

Often, an oversized engine running mostly at half throttle during the flight will actually burn less fuel than a small engine that's always screaming to keep the plane in the air.

If the firewall is glued in with epoxy, you can remove it by using a monokote heat shrink gun. Heat the epoxy up to 400 F and the glue melts and lets go. Patience, it takes a few minutes.
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Old 12-28-2007, 08:02 AM
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Default RE: Firewall removal

Snaker,
Quote:
ORIGINAL: Flylow

Snacker - I'm putting a Kadet Sr. ARF together right now. I see no need to remove the firewall. To put a larger tank in, I would use my Dremel tool with the flex shaft to get in and modify the factory tank cutout. No problem going in through the cabin area with this. Tower Hobbies site gives dimensions of most tanks they carry. If you don't have the Dremel tool just get a small rough cut file. Slower, but it will get the job done too.
Do what Flylow said. Buy a Dremel with a flex shaft and use it to cutout the formers. You'll find a lot of uses for the Dremel.

Make up a shelf out of balsa to fit the bottom of the enlarged formers, or bridge the gap with two balsa sticks glued to the bottom of the enlarged formers. The balsa sticks provide support ie two beams across which the shelf is glued on. Dry fit everything. Try to make the center of the tank even with the spray bar on the engine.

Glue some 1/4 sponge rubber onto the top of the shelf. Have the tank all plumbed up and water tested for leaks. Zip tie the tank to the shelf and test for fit. Use some epoxy to glue the shelf in place with the tank zip tied on top and the hoses threaded through the firewall.

Trust me this will take a lot less time than trying to rip the firewall out of the fuselage, and you won't have to recover anything.

Most of all take your time and have fun.
John
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Old 12-28-2007, 08:52 AM
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Default RE: Firewall removal

The Senior Kaydet has a hugh caniverous area for the fuel tank. Do not remove the firewall. This is obviously the ARF version since you are reluctant dig out the internal supports for the Usually poor quality arf tank as suggested in other posts.

Its a simple matter to just glue in a couple of cross sticks from the backside for new supports of any tank you want. Then push it in with some foam, Also do not push the stopper bung throught a hole in the firewall as you discussed in another thread. This can and will cause foaming.

If you want to get fancy its not very hard to create a simple access panel on the bottom for easy access to the tank compartment area.

I highly recommend you use of whatever size you choose a genuine Hayes tank (not a chinese ripoff) as these are not only simple but arguably the most trouble free tanks of all.
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Old 12-28-2007, 09:11 AM
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Default RE: Firewall removal

I also agree that you should NOT remove the firewall.

If you can't get a Dermel in ther, just get out your hobby knife and start hacking away.

Looks won't matter cause once the wing is on, no one will see it.
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Old 12-28-2007, 09:43 AM
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Default RE: Firewall removal

That's a lot of engine on that particular plane. You sure you want to do that?

CGr
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Old 12-28-2007, 11:22 AM
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Default RE: Firewall removal

Ok, thanks guys. I think I will do my best to replace the tank without removing the firewall. If I do a little research I could probably find one with the same diameter and maybe just a little longer. I'll sand down the inside supports and then I'll pack it in with some foam since there's no room for foam with the stock tank anyway.

I know some people have thought this engine is to much for this plane but I'm not going to be flying at full throttle anyway.

Thanks again.
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Old 12-28-2007, 12:42 PM
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Default RE: Firewall removal

i have a kadet kit that when i first built it i put a OS 40fp and it flew very well when i toyed with the idea of flying off the water i installed a OS 61fs on and installed a 16oz tank i fly it over a hour at a low power setting and it flys great as for the larger tank i cut a large square in the top to change tanks it was easy // try it and good luck
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Old 12-28-2007, 12:43 PM
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Default RE: Firewall removal

One of my favorite tools is a half round metal file. About 8-10 inches long. It has a rough tooth pattern, very agressive for metal filing, but it does a wonderful job on balsa and ply. If you can't apply "more power" this might work for you.

Also, Xacto has a blade for the #2, it's got a saw tooth pattern. I don't use it much, but it might work in your application.

Another interesting tool.. A hole punch. A good one meant for punching through leather. You could conceivably punch a series of holes in a piece and "connect the dots" with a knife or something later.

Good luck...
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Old 12-28-2007, 01:17 PM
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Default RE: Firewall removal

I have replaced a number of firewalls because of unfortunate ground contact. Replacing the firewall is the most difficult method imaginable to have a bigger tank. Find another method. Sand or saw the former behind the tank. Use a second tank. Anything but don't take the firewall out.

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Old 12-28-2007, 11:16 PM
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Default RE: Firewall removal

Lots of good ideas that I never thought of, or would even consider doing until now. Thanks gang!

Redbluffwingnut, since you've done this before, I was wondering what you used to cut open the top of the plane and what kind of tank did you use. Will it mess up the covering?

Thanks.

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Old 12-28-2007, 11:39 PM
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Default RE: Firewall removal

Quote:
ORIGINAL: clouddancer


Quote:
ORIGINAL: dragnbye

alot of people seem to just fly them into the ground, most of the time that will free them right up
That is funny Though not very helpful in solving the problem.
good humor helps! and I think that might have been a voice of experience

If carefully cut out you can reseal the hatch with clear monokote strips. [8D]
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Old 12-29-2007, 09:01 AM
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Default RE: Firewall removal

You use a razor saw and the covering is going to be messed up a little. I would reinforce the section I cut out with balsa. Make a ledge and use it to screw the hatch back down into the fuse with. Cutting the formers on the inside is easier.
Just my opinion.
John
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Old 12-29-2007, 09:27 AM
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Default RE: Firewall removal

Web page showing the kits fuel tank placement. I do not know if the ARF is built the same as the kit but it might give you some ideas.
http://www.ncn.net/~chasnoble/rc/kadet.html
Flex shaft
http://www3.towerhobbies.com/cgi-bin...?&I=LXC523&P=7
Xacto saw blades
http://www3.towerhobbies.com/cgi-bin...lade&search=Go
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Old 12-29-2007, 09:43 AM
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Default RE: Firewall removal

The Xacto saw blade fits into a standard holder. It should be really easy to use.
John
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