RE: df engine and fan unit upgrade
 

B1,

Do you think fuel distribution weight will be fine from the original position of the tank???? I mean as during flight the balance weight will change?

Or is that, as long as the balance weight (dry) is the original 200mm back when fuelled it will compensate with elev???

need help!!!!

RE: df engine and fan unit upgrade
 

And does anyone know what this is for?????? I bought my RK-740 2nd hand, and without many of the bits it needs (now on order)

Where does the thing below go???????

RE: df engine and fan unit upgrade
 

is it an engine mount you screw onto the backplate of the engine or something ?

RE: df engine and fan unit upgrade
 

Don't think so SJ.

Anybody know???

RE: df engine and fan unit upgrade
 

Dave, I think the original location of the tank is fine...where else you gonna put fuel. Your right, as long as the dry weight balances fine your allright. I'd keep that tank right where it is.


Luis

RE: df engine and fan unit upgrade
 

Thanks. That means this evening, i gotta cut some of the wing away.

You have an A7 don't you? (maybe i'm thinking of another person)

RE: df engine and fan unit upgrade
 

You gotta cut room for the tank? Yes, I have one of them A7's. Great flyer. If you setup goes good, I might do it myself. Keep up the posting.

Luis

RE: df engine and fan unit upgrade
 

Dave, That part you asked about is the rear engine support ring. I also have an RK-740 and the instructions. If you don't have the instructions I would be happy to scan them in for you.

Just went and looked over my parts, it looks to actually be the Tank Tube Mount Ring, but is seems to have been cut out at the botton. My ring is a full circle.

Thank you,
PigHeaded

RE: df engine and fan unit upgrade
 

Ph,

Thanks for the offer of the instruction, but i've just ordered all the parts i need from Kress, including instructions.

Thanks. Yes B1 i have to cut the front of the wing what it sits on the ledge behind the fuel tank!

I'll put some progress photos up tonight.

Cheers all
Dave

RE: df engine and fan unit upgrade
 

Hi all, Not getting much time to devote to my A7 at the moment.
However, have decided it's more trouble than it's worth to cut throught the wing to let the fuel tank through, so it'll will go as far back as it can and be left hanging out in the cockpit.

However, my next problem has arrisen. The outlet duct in the A7 is 3.75" and my Kress fan is 4" and i can't get one to fit in the other.

Can anyone suggest anything?

RE: df engine and fan unit upgrade
 

Exterior

RE: df engine and fan unit upgrade
 

If the fan area is 4" across then shoe horn that puppy in thru the wing saddle area, with the numbers you gave your outlet to FSA is around 87.9%. That's close enough to the 90% mark your looking for, just make sure that your intake is not smaller than the FSA. Plus I would put the tank in the wing to help maintain the CG point, on such small models the CG is very sensitive, espiecally since the fuel we're putting in can weigh 25% of the models weight.

RE: df engine and fan unit upgrade
 

Can't move the fuel tank! no room!
I did drop all the parts into the A7 that will be in there when it's completed and in their rightful places, and the plane still balances in it's original CG location! wooooooo hooooooo!

Did buy a ducting cone. Moves 100m down to 62mm. I'll cut it so that it will be 100m down to 95mm!!!!!

Thanks for you input, much appreciated.

RE: df engine and fan unit upgrade
 

The A7 has cheater inlets on the sides of the fuz. These are restricting movement inside the plane and making things difficult.

Can any of you forsee any problem if I remove these inlets, and just have the one nose intake?
remember there is going to be no little toki fan in there but the more powerful kress rk-740!


Thanks
Dave

RE: df engine and fan unit upgrade
 

Every little bit helps but in your case those little holes are not going to show much difference. The kress is pitched much more aggresssively than the toki and it's going to draw the air in no matter what. You'll know if you have a small inlet if the motor over-revs from the vacuum created, or worse, your engine over-heats. Just don't implode the plane, HA HA![:-] I put some pic's of my kyosho f-86 and you can see the mods to the wing to hold the tank there and I put two hs-85mg in the wing. I decided to recover the plane in olive drab with a military tan camo scheme. So the whole thing is apart for the painting process but she'll be back together in a few days. I'm still toying with the idea of mini retracts but I have to figure out where to put the servo. I'm also thinking about a kress-709 with the mvvs 15 engine. or I could diesel the O.S. 15 and use 2/3 the fuel, big weight savings.

RE: df engine and fan unit upgrade
 

Thanks PB66,

Whats the diameter of the ducting in the F86?

RE: df engine and fan unit <span class=
 

http://www.rcuniverse.com/forum/fb.asp?m=1372743&key=

RE: df engine and fan unit <span class=
 

The fan unit in the F-86 is 90mm and overall height from top to bottom inside where engine mounts is 121.67mm/4.79". If you divide that number in half I have almost 61 mm from engine beam to fuse top clearance, but you'll have to subtract about 5mm for head clearence. so if I replace the fan unit with another system it can't have a radius of more than 55mm from the center of the crank on motor. maybe I can sqeeze a hot .21 on a 720 kress fan in the fusealage, I'll have to go to the hobby shop and check out the motor heights, including that I hack off 2/3 the buggy cylinder fins. It shouldn't over heat with the air flow of the fan unit.[:-]

RE: df engine and fan unit <span class=
 

That's another problem I have. The top of the picco 45 is not in the airflow. It's half sticking up through the wing. So I've bought vents, so that when the plane's moving, air will be forced down over the engine. I can't think what else to do?

RE: df engine and fan unit <span class=
 

How about running your kress fan with a [link=http://www.modelengine.com/aero/ductedfan.htm]K&B (3.5) Ducted fan engine[/link]


Or the OS 25. There's one on ebay now! do a search for "Ducted fan" there's an OS25 there!


Good luck. Let me know what you get.
Merry Christmas
Dave

RE: df engine and fan unit <span class=
 

You could use the louvers or put a engine cover on the fan unit like the one I have for my turbax unit, it forces the air to go thru the cylinder head and not around it. Like I stated in other posts on baffles, air is stupid, you have to show it where to go and get it out just as fast. Here's a pic of the head shroud.

RE: df engine and fan unit <span class=
 

If you look back at my post #17, you'll see what my problem is. I don't really want to hack the carbon fibre shroud, to force air over?

RE: df engine and fan unit <span class=
 

In that case you'll have to use a scoop or a louver like you have, that way the vacuum created by the exaust tube will draw air over the cylinder head, it should work fine and not present any issuses if the opening is suffecent and the duct work is right.[:-] " YOU CAN DO ANYTHING YOU WANT, IT JUST DEPENDS ON HOW MUCH OF AN ANIMAL YOU ARE! ":D

RE: df engine and fan unit <span class=
 

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