Am i taking risks???
 

Hello,

I am about to put the final touch on my Feibao Rafale, and i have found out "late" that my air system is leaking. I have a UP3 valve to activate gears and doors.

Here goes what's happening:
When gear is down, air stays in system for about 24 hours, but when gear/doors are closed, pressure remains for about 25 minutes before reading on gauge goes to minimum pressure.

My questions are as follow:

1) I know that i should have installed a Tamjet gear failsafe unit (which ironically, i already have), but i will create a big mess if i do so now.

2) is there anything i can do to improve my system and reduce air leak, bearing in mind that most of the equipment/connections are buried under trays/turbine etc...

3) is it safe to fly with system as is, bearing in mind that when gear is down system's leak is not critical at all, or will this leak increase with time?

Appreciate any input/good advice that would make my life easier.

Thanks. Regards.

RE: Am i taking risks???
 

1. How will this create a mess, it takes 5 minutes to install and just needs to be T'd into the system.

2. Use safety wire on all the connections and use soapy water to check for leaks.

3. I would fly if it was the other way around, leaking in the down and sealed in the up, but not the way you are saying, at least not without a failsafe.

Thats just my .02;)

RE: Am i taking risks???
 

I know you said you have problems with access - but if you can get to the various airlines with some hemostats, try crimping each off in turn in order to isolate which line the air is causing the leak.

RE: Am i taking risks???
 

Why not fly it, and leave the gear down; then when you find out how well it flys you will have no problems in spending the time to sort out the leak.

RE: Am i taking risks???
 

Ianober, Gordon Mc, CollinW,

Thanks for your input. Onre thing i forgot to mention is that i can cycle the system 6 to 7 times before i emptying the air bottle.

I also needed to rule out that leak was not caused by the valve itself.

CollinW, i don't think the doors would wistand high speed while they are in open position, but presume your advice is to work on the plane as it is worth the trouble.....

Thanks again
Regards.

RE: Am i taking risks???
 

Hi, try to get in some silicone spray int the system it will take care of a minor leake. When I have leakage in the gear system I also try to put some low viscousity silicon oil into the tubing and after doing that it is usually leakage free.

When I was building my Rafal I had to take a part 2 out of 3 cylinders and lubricant all the O-rings inside, then it was airthight, a note though it was not the standard mecanisms including in the kit.

Please send us some picturers of your rafal, engine instalation and so on, it always good to compare instalations.

Best regards, Kjell-Åke

RE: Am i taking risks???
 

Kjell-Åke,

Thanks for your thoughts. Could you please advise where can i get such product and how to inject in the system?
Details would definitly be appreciated.

Will include more photos asap.

RE: Am i taking risks???
 

Hi, I insert into the system by using a, Oh i dont have the english word, when you are goint to have a vaccination the nurse have this whith a needle and sticks it to the arm. Thats is the gadget I am using, take apart the system after the valve and insert a amount of oil into the tubing, put it together and pressurise the system. Try to disconect as close to the cylinders as possible to bee sure that the oil gets all the way into the cylinders.

Do this a couple of times so that all cylinders get oil. The silicone oil you can buy at a hobbystore, I use the schock absorbing oil that RC cars uses, a low viscousity one, around viscousity 10.
I also use this oil in the start system to lubricant the O-rings in the valves for the Propane.

For lubricant in aircylinters if I take them apart I also use the same oil but whith a viscousity of 60 to 80, much thicker and slow running.

As Propane is very dry the O-rings need some oil from time to time.


Nice picture of the instalation, is it a P120?, Lots of extra fuel:D


Best regards K-Å

RE: Am i taking risks???
 

Do your best to find and repair the leak, when all else fails just add another tank for more air volume which should give you additional time. I swear by the Tams failsafe, install it !!!
V..

RE: Am i taking risks???
 

Thanks again guys,

Kjell-Åke,

Will try to get some silicone oil somehow and inject with "seringe" in the system and see how it goes. And yes this is a P-120 and saddle tanks are for smoke....

Vincent,

If silicone sealant will not work i'll have to go for the Tam's failsafe unit to stay on the safe side of the story!!!

Thanks and regards.
Dany

RE: Am i taking risks???
 

So why not just fix the leak? your model is worth a lot of $$$ and not worth risking damaging! so a few extra minutes to source leak is the logical (to me ) solution.

The method I use to find air leaks-
Grab a piece of Tygon fuel tube approx 2' in length then hold one end close to ear while running other end over all air line connections and valves, you will hear an amplified "leaking" sound when you come across the problem air leak, its that simple! no soap, no fuss and quick to the source and obviously always easy to keep a spare length of tube in the tool box for field check/repairs as well ;)

RE: Am i taking risks???
 

Jet Fx,
Dany said his air system will hold for 25min, this is a very slow leak. It may be very hard to "hear" the leak with your tubing idea??

Also Dany, do not forget about the air gauges and filler fittings, they can leak too.
V..

RE: Am i taking risks???
 

As per Vincent,
The one that usually we all miss is the fibre washer on the air gauges.
All the best,
John C

RE: Am i taking risks???
 

Vin you could be right there.... to be honest though I have never had a leak that could not be sourced using this technique the tube amplifys the sound quite dramatically to the point of being able to hear leaks that you cannot by using ear alone, sort of like a stethoscope in effect! I would be surprised when using this method if the source remained a mystery for long. 25 min is ok but odds are it will begin to leak air faster and especially when it matters.

I remember a converstion I had with Tom Cook about leaking air systems and pressure duration, He said "3 months" would be more like it! (He was refering to the gear system in his Firebird at the time) Wow! :D

RE: Am i taking risks???
 

JET FX,
I am going to keep your idea in my pocket and use it some day to find a leak. It is a daunting task to look for a leak in a plane with a mile of tubing a fittings going in and out of everywhere. I spent the better part of an afternoon looking for a slow leak in my CARF Mig-15 and it ended up being both air guages which were staring right at me the whole time...ugh.

V..

RE: Am i taking risks???
 

If this kit purchase direct from FB or other dealers using FB gear?
The leak mostly coming from the retract air cylinders. Some can be fix with thick selicone lube and turn the air cylinders in all the way and tight.
I had few of those gear and most of them have the same problem. That why we offer the kit we sold with our gear.

RE: Am i taking risks???
 

I had a leak in my JL F-15 and of course it was the last place I looked. The fill fiitting. I would guess that since yours is leaking when the gear is only up, the fill fitting and pressure gauges would be ruled out but of course check them anyway.

Marty

RE: Am i taking risks???
 

25 min????? What you waiting for??? Giddy up and fly that thing...;)

RE: Am i taking risks???
 

Just one observation: how much mess would a belly landing make ??

RE: Am i taking risks???
 

1 foamy in the air and it matter air leak or not.:D:D:D


Ronald R Long

RE: Am i taking risks???
 

Thanks again for all your valuable inputs which are very much appreciated.

I liked the idea of the "stetoscope". I will give it a try and see or should i say "listen" for a whistle!!!

Meantime here are a few more photos of my installation. Planing to install base loaded whip antenna inside nose cone (see below)

Regards to all.

Dany

RE: Am i taking risks???
 

Nice instalation picturers, I have the same aeroplane but in camo colours, I will use an P80 in my Rafal, have you linked the canard to the elevons? Or do you use a separate switch for the canard?

http://www.rcflyg.se/album_pic.php?pic_id=1891
My instalation i an early stage.

I have used a rather expensive retract and that did not mean that it was leak free, I had to take apart 2 out of 3 retracts and change O-rings due to air leaks.

K-Å

RE: Am i taking risks???
 

K-Å

I also have another Feibao Rafale new in the box, the camo version.
Frankly speaking, although they look nice, I didn't like much the FB retracts that came with the kit as they have some play in open/locked position which I hope will not be a problem on not so soft landings.

I noticed that you have ferrites on your servo cables although you are using a power box?? Is this necessary?

As for the canards, i haven't yet done the mix but intend to have both continuous mixing with elevators and an offset position for take off and landing activated by a 3 position switch.
I have a Futaba 9Z radio and have not yet tried thesettings but in a previous thread i have received some intersting advice to dial some delay in travel play which apparenly will make the Rafale fly realistic.

Can't wait to put the final touch and fly this beauty!!!

Regards.
Dany

RE: Am i taking risks???
 

Hi Dany, the ferrit rings was put there by Powerbox so I just let them stay where they are.
I have used som hevy duty retracts on mine as I am going to fly it mainly from our grass field which is currently covered in 50cm of snow and will be so for the next months.

I hope I can fly it from our field in May if we have a good spring.

Our season is quite short between may and oktober, but on the otherhand we have enough light for flying around the clock in may and june.

By the way Dany have you figured out where to put the 2 plywood blocks that is supplied in the kit and has the text jetcat on them??

I have tried to fit them but they don´t seem to fit anywhere!



BRG K-Å

RE: Am i taking risks???
 

K-Å,

what 2 plywood blocks are you talking about? havent received any I only have in mine 5 or 6 small square blocks which could be used to support central Fuel tank and eventually help installing plywood plate for ECU equipement.... Do you have any picture?

In Lebanon, we can fly all year long although we have snow sometime on our field. Check this link:
www.amazrc.com

Regards.
Dany