RC Jets Discuss RC jets in this forum plus rc turbines and ducted fan power systems

Question on F18F from X-Treme Jets

Reply

Old 09-07-2019, 04:34 AM
  #1  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Question on F18F from X-Treme Jets

Hey guys,

I am restoring an F18F from X-Treme Jets (the entry model from Skymaster Jets) : http://www.skymasterjets.net/f18e.htm
I am stuck at the tanks plumbing, there is 1 big kevlar tank, 2 smaller kevlar tanks and one UAT. I will be using a Jets Munt M166TS.
Can someone share or explain how should I plumb all the tanks together ? What size of tubing do I need to use, 4mm or 6mm ?
I have to order a new UAT and I was thinking about the Intairco iTrap but I wonder whch size I should pick : https://www.final-modellbau.de/en/ac...cessories.html
I was thinking about the iTrap 175ml Basic, but what kind of fitting would you recommand festo 4mm ? 6mm ? Barb fitting ?
Thanks a lot for any help guys.

Regards,

Jimi
jimibar is offline  
Reply With Quote
Old 09-07-2019, 05:54 AM
  #2  
gunradd
My Feedback: (9)
 
gunradd's Avatar
 
Join Date: Aug 2008
Location: Springhill, FL
Posts: 3,139
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Depends on the tank locations. Allot of times though you can plumb them all in series. So you can go from vent line to the small saddle tank. Then the other saddle tank. Then the main center tank to the uat.

Plumbing this way drians each tank 1 at a time. This helps with keeping the last tank full longer getting less air in the system.
gunradd is offline  
Reply With Quote
Old 09-07-2019, 06:16 AM
  #3  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by gunradd View Post
Depends on the tank locations. Allot of times though you can plumb them all in series. So you can go from vent line to the small saddle tank. Then the other saddle tank. Then the main center tank to the uat.

Plumbing this way drians each tank 1 at a time. This helps with keeping the last tank full longer getting less air in the system.
Thanks a lot for your reply Gunradd,

The UAT is in front of the main tank and the saddle tanks are behind the main tank on the side of the turbine.
Mind sharing a diagram or something, I must say it is not pretty clear

EDIT : Nevermind, I got the plumbing in series
jimibar is offline  
Reply With Quote
Old 09-07-2019, 06:49 AM
  #4  
Ceeray
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 272
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I had one with one single large 3liter tank between intakes. Saved a lot of hassle..
Ceeray is offline  
Reply With Quote
Old 09-07-2019, 01:08 PM
  #5  
ravill
My Feedback: (11)
 
ravill's Avatar
 
Join Date: Jan 2003
Location: Granite Bay, Ca
Posts: 4,955
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Series is good. You can also plumb the saddle tanks to drain into the front tank. I would choose series because it simplifies the tubing. The last tank in series has to vent to the outside of the jet. I like to make the vent accessible so I can hook up my jersey modeler to catch the overflow

In the tanks, use BVM in tank tubing (cut it 3/4” shorter as it expands in the tank) but it stays pliable for the life of the jet. Use large or extra large Tygon for the rest.

You will only need 6mm from the front of the UAT to your pump. Your turbine will be fine with a medium sized UAT. Once you get to 180N+ turbines will it become critical to use large fittings.

I like barbed fittings on the suction side secured with safety wire. Many people use festo on the suction side, so it probable doesn’t matter. It helps me sleep better at night though!
ravill is offline  
Reply With Quote
Old 09-07-2019, 01:43 PM
  #6  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Thanks Ravill for all the answers.
I will order the 175ml then and will do the plumbing as you said.
jimibar is offline  
Reply With Quote
Old 09-16-2019, 02:03 PM
  #7  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by Ceeray View Post
I had one with one single large 3liter tank between intakes. Saved a lot of hassle..
I just exploded my main tank so I have to find another solution. Where did you get your 3 liters tank ? Is one big tank enough ? I am planning an M166TS in my F18.
Where can I get a tank for this plane ? I just sent a mail to Xtremjet but they are usually long to answer.
jimibar is offline  
Reply With Quote
Old 09-16-2019, 06:55 PM
  #8  
Ceeray
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 272
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I did not build it myself, but I think any generic tank which fits between intakes is good. Onlu downsize is that then the fuel sits in front of the CG..
Ceeray is offline  
Reply With Quote
Old 09-17-2019, 03:31 AM
  #9  
ravill
My Feedback: (11)
 
ravill's Avatar
 
Join Date: Jan 2003
Location: Granite Bay, Ca
Posts: 4,955
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Why did your main tank explode? Was there too much pressure in it? Did it drop and break?

It's likely repairable too. Post pics.
ravill is offline  
Reply With Quote
Old 09-17-2019, 07:32 AM
  #10  
Craig B.
 
Join Date: Dec 2002
Location: PERTH, AUSTRALIA
Posts: 1,367
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I fly one of these powered by jet cat 160. Rear tanks empty into front tank then to small INTAIRCO header. Only 6mm festo tubing. If you go smaller you are asking for cavitation problems, especially if plumbed in series. Plumbed in series can introduce lateral balance issues on flight. Not my choice of setup but others have apparently used this successfully.
Craig B. is offline  
Reply With Quote
Old 09-17-2019, 10:42 AM
  #11  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by ravill View Post
Why did your main tank explode? Was there too much pressure in it? Did it drop and break?

It's likely repairable too. Post pics.
Too much pressure and the tanks was already repaired by the previous owner and was really old from what I see.
I really don't want to repair it or even go with the 3 tanks setup. I would prefer to use only one bigger tank. What size of tank would you recommand ?
According to Jet Munts, the M166TS has a fuel comsumption: @160N: 460g/min. 3Liters might be a little low ? 4Liters ?
jimibar is offline  
Reply With Quote
Old 09-17-2019, 10:58 AM
  #12  
Ceeray
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 272
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

3l can with jm 200xbl was good for 7 min spirited driving and extra 1min for problems..
Ceeray is offline  
Reply With Quote
Old 09-20-2019, 11:34 AM
  #13  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I found the perfect tank. CMJets is producing a 4L Kevlar tank for the F18F Jet Legend. A little expensive but wortht the money I'm sure.
jimibar is offline  
Reply With Quote
Old 09-20-2019, 03:05 PM
  #14  
Craig B.
 
Join Date: Dec 2002
Location: PERTH, AUSTRALIA
Posts: 1,367
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I wouldn’t have all of that fuel sitting way in front of the c of g. The super hornet has a tendency to leap off the ground and this is exacerbated if you have a nose heavy model on takeoff.
Craig B. is offline  
Reply With Quote
Old 09-20-2019, 10:05 PM
  #15  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I agree with you but the 4L tank is sitting at the same place as the old bigger one, which is not that far from the CG. I'll try to balance the plane with bearing in mind the heavier tank in front.
What do you think Craig ?
I really don't want to mess with 3 tanks + UAT ...
jimibar is offline  
Reply With Quote
Old 09-21-2019, 01:26 AM
  #16  
Ceeray
 
Join Date: Dec 2006
Location: Kuopio Finland , EU
Posts: 272
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Takeoff wirh flaps and no hopping tendencies.
Ceeray is offline  
Reply With Quote
Old 09-21-2019, 06:08 AM
  #17  
Craig B.
 
Join Date: Dec 2002
Location: PERTH, AUSTRALIA
Posts: 1,367
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

It will still leap off the ground with flaps if the fuel load makes it appreciably nose heavy. I had a bad experience with a yellow hornet for the exact same reason. Superhornet is worse than the C model in that respect because it was aerodynamically designed to stand on its tail with large LEXs.
Just my experience....
Craig B. is offline  
Reply With Quote
Old 09-24-2019, 01:50 PM
  #18  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Ok guys, another issue ...
I've installed the elevator servos, it looks ok but I wonder if the small play is normal ?


I assume it was flying like that, any chance of flutter ? i'm using the stock command ... with aluminium control horn and MP Jet link ball ...

Is the "shaking" normal ?
jimibar is offline  
Reply With Quote
Old 09-24-2019, 03:46 PM
  #19  
ravill
My Feedback: (11)
 
ravill's Avatar
 
Join Date: Jan 2003
Location: Granite Bay, Ca
Posts: 4,955
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

That amount of play looks pretty normal. Those full moving stabs will transmit even small gear train slop.

And what people are saying about hoping off on take off is real. Use lots of flap for take off. Landing is around 45 degrees and take off is 35-40 degrees.

We’ve had lots of hornet experience around here.
ravill is offline  
Reply With Quote
Old 09-25-2019, 07:16 AM
  #20  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by Craig B. View Post
It will still leap off the ground with flaps if the fuel load makes it appreciably nose heavy. I had a bad experience with a yellow hornet for the exact same reason. Superhornet is worse than the C model in that respect because it was aerodynamically designed to stand on its tail with large LEXs.
Just my experience....
Any chance I can work around that to reduce this hopping tendancy ? Should I balance the plane with tank full for exemple ?
Or the only option is to keep the 3 tanks ?
jimibar is offline  
Reply With Quote
Old 09-25-2019, 08:41 AM
  #21  
Canadian Man
My Feedback: (1)
 
Canadian Man's Avatar
 
Join Date: Aug 2008
Location: Calgary, AB, CANADA
Posts: 274
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by jimibar View Post
Any chance I can work around that to reduce this hopping tendancy ? Should I balance the plane with tank full for exemple ?
Or the only option is to keep the 3 tanks ?
I fly a Tams F18 Hornet. 1/8 Scale. when I first got the plane I experience the jump off the ground. All fuel is in the stock location between intakes and it's about 5L of fuel with stock tanks.
Here is what I did to solve the problem.

- Flaps on take off as has been suggested.
- Make sure the plane has a decent positive angle of attack when full of fuel. I added an extender to my nose gear to ensure
the positive angle. Even with the front strut compressing about 1/2 way on the nose when full of fuel.
- Get up to a decent speed and pull gently back on the elevator. Dont mash the elevator.

These things made for a beautiful smooth take offs.

Jonathan
Canadian Man is offline  
Reply With Quote
Old 09-26-2019, 01:55 AM
  #22  
Craig B.
 
Join Date: Dec 2002
Location: PERTH, AUSTRALIA
Posts: 1,367
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by Canadian Man View Post
I fly a Tams F18 Hornet. 1/8 Scale. when I first got the plane I experience the jump off the ground. All fuel is in the stock location between intakes and it's about 5L of fuel with stock tanks.
Here is what I did to solve the problem.

- Flaps on take off as has been suggested.
- Make sure the plane has a decent positive angle of attack when full of fuel. I added an extender to my nose gear to ensure
the positive angle. Even with the front strut compressing about 1/2 way on the nose when full of fuel.
- Get up to a decent speed and pull gently back on the elevator. Dont mash the elevator.

These things made for a beautiful smooth take offs.

Jonathan
Jim, do what Jonathan suggested above. In all of my hornets I have lowered the nose gear to ensure a positive AOA on the ground; especially under load on takeoff. All you have to do then is go gradually on the elevator and your will see the nose get light. Don't yank on the elevator. I turned up an insert out of delrin that I inserted into the nose leg strut to limit nose gear compression and I shimmed the nose gear retract down in the fuselage to increase the AOA on the ground.

Do not under any circumstances move your c of g back to compensate for forwards fuel placement. I maintain you are best to go with the 3 tanks, plumbed in parallel a the back feeding the front tank in the super hornet.

BTW, that slop in your stab is no good. The stock skymaster arms are way too short and this leads to poor holding power, poor stab resolution and slop as you have seen. I ALWAYS lengthen my control arms on my skymaster jet's stabs. Will see if I can find some pics on how I did it to show you. All you need is some 3mm aluminium sheet and a few bolts....dead easy. I end up pretty much doubling the effective length of the control arm. No way would I fly it like that but others have and gotten away with it. Just asking for trouble though in my view.
Craig B. is offline  
Reply With Quote
Old 09-26-2019, 02:14 AM
  #23  
Craig B.
 
Join Date: Dec 2002
Location: PERTH, AUSTRALIA
Posts: 1,367
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Jim, check out post #6 on this thread.....

My Skymaster 1/8 F16 Fitout
Craig B. is offline  
Reply With Quote
Old 09-26-2019, 05:58 AM
  #24  
jimibar
Thread Starter
 
Join Date: Nov 2015
Posts: 81
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by Craig B. View Post
Jim, check out post #6 on this thread.....

My Skymaster 1/8 F16 Fitout
Ok I understood what I need to change, but ... how do I access there ? The dual thrust tube is sitting there and can't be moved ?
jimibar is offline  
Reply With Quote
Old 09-26-2019, 06:09 PM
  #25  
Craig B.
 
Join Date: Dec 2002
Location: PERTH, AUSTRALIA
Posts: 1,367
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

You should always be able to remove the thrust tube for servicing. Why can't you take it out? Normally they are just held in place with screws at the forward end.
Craig B. is offline  
Reply With Quote

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service