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Fei Bao F86 1/6.5 Build Thread

Started by STORM, October 20, 2011, 20:23:59 pm

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STORM

After this I razor planed some material off the botton flap t/edge skins to get enough movement. The flaps and ailerons are not permanantly attached yet so this is the time for hacking while it's gettatable.
I noticed that the top laquer coat was peeling a bit from the trailing edge, this had already happened on the silver servo panels which I don't mind, I removed it, it just peeled off.
I'm a bit concerned that the clear laquer does not like sticking to the silver paintwork, it appears to be ok on the coloured area's, I'll have to keep an eye on it.

STORM

Now time to fit the flaps, firstly I assembled the wings to the fuse to get the inboard position measurement noting that as usual when the flap was in deployed position it fouled the fuse at the root, usual technique is to take material off the flap but in this case I am going to remove material from the fuselage to clear.
The two flaps were then installed.
Interesting to note that while I was doing this I clocked that FB have built in a sizeable amount of washout (or it's a big warp) ;D
I understand that this is more important than usual as it is a swept wing design which is more susceptible to tip stalling, especially in turns as one wing tip is flying faster than the other. Harry & Peter I will stand correction on this if you know different.

STORM

The sequencer has now arrived and been fitted, sod's law of course the doors need reversing but I think I can do that on the valve programming which will have to be done before the inlet duct is finally installed.
One good reason for only using low air pressure for setting up!
However, no air leaks were found and everything, including the air brakes appear to work ok.

STORM

Whist the wings were on it became apparent that the holes for servo leads and air fittings were not large enough and the gear legs fouled the fuse root when fully closed, this was rectified with the trusty Dremel.

STORM

I could do with some advice now.
The front aux gear door has no means of being actuated. I assume that FB expect the door to be pushed open by the gear which it would, and closed by air pressure, which it also would.
I have to provide a way of attaching the door to the leg to hold the door closed, the door is not scale, as far as I know the f/s is hinged across the centre and therefore split in two but I'm going to leave it as supplied for simplicity.
When the leg opens and closes whatever way I use must enable it slide up and down the leg. I could use a small spring or even a rubber band but it would not look nice, any bright idea's anyone?

Roger M

On my Ultra Flash I use a small magnet projecting slightly from the fuselage and a small piece of tin plate stuck to the door. This keeps the door closed for transport, but allows it to easily open when the leg comes down and when the leg goes up the air pressure closes the door.

Roger

Thommo

Fighteraces supply these door clips which may suit.

"Glass Filled Nylon 'Snap On' landing gear door mounting blocks.
Supplied in a pack of four in the following sizes

to fit 3/8, 1/2, 5/8, and 3/4 inch diameter landing gear legs

All £5.80 + P&P"

[attachimg=1]

STORM

Thank you both for those suggestions, much appreciated.  :af

Alex48

Hi Gary

Is the oleo oil damped or does it use a spring?  If its the latter you could tap the oleo and use M2 ball ends and studding to make a little linkage up that attaches to the gear door.  I did this on one of my builds and it worked out fine.  The door would stand proud of the oleo by the length of the linkage. 

Cheers, Alex 
The Little Jet Company
www.facebook.com/TheLittleJetCompany

HarryC

Quote from: STORM on November 27, 2011, 13:48:42 pm
as far as I know the f/s is hinged across the centre and therefore split in two but I'm going to leave it as supplied for simplicity.

It is indeed, I tried to replicate it on my original F-86 but with no success, I took close up photos of the linkage when the f/s was at RAF Hendon but it was not possible to replicate.  It's easy enough to cut it in two and hinge it, the problem is getting it to close flat and yet open bent like <.  So after much faffing I opted for a one piece door and it looks fine.  Few people will know it is not right!  I moved it by a method you may not like since you don't want a spring etc looped around it.  I glued a piece of 1/4 ply edge on to the door to rest against the leg, and gently ground out a circular groove where it rests against the leg.  With the leg full retracted, close the door, and see that the door is still not closed, grind out a bit more from the groove, test door closing and repeat until the door just closes perfectly with the wood hard up against the leg.  Cut off a bit of cable tie and make a half-loop around the leg, screwing both ends into the wood.  Paint the wood and cable tie silver.

A problem with the Sabre is that the noseleg is (or should be!) a twist and turn unit which on models means the whole leg rotates 90 degrees and makes it impossible to use a control arm from the leg to the door

I have the problem again, having acquired another, slightly bigger Sabre which has the split hinged door and a spring around the leg but does not close properly.  I have some more ideas this time, and a better supply of springs so will report back shortly.

STORM

If I did your method Harry it may work ok as when the leg and door are up the leg goes in further than a standard retract as it's a home made non rotating job from FB so I probably would not need a groove in the block.
Alex, I can't do that because when its all open there is no gap between the oleo and door, any further and it would break the hinge, especially on the Sabre as the leg is angled forward when open as you know.
Plenty of idea's to develop now though, thanks guys.
Harry, if a one piece door is ok for you it's ok for me! I don't actually mind a spring, but a rubber band on a jet for me is a big no-no.

HarryC

This is how it looks with a 1 piece door, seems fine to me, only Sabre enthusiasts would realise it is not right

STORM

That's cool Harry, not a lot of flap though.
They tell me Sabre's do not need much aileron movement, do you find that?
Nice to see all your other doors up.  ;)

HarryC

that photo is at take-off, (lozza risking life and limb to stand in front of it and take a sequence of shots,) hence the smaller amount of flap.  I guess it is not much aileron travel, but none of my scale jets do have much aileron travel.  With small spans or swept wings rather than long span straight wings like the boomer, the aerodynamic damping is less so I guess it must mean less force to get things moving.
Be prepared to either accept the Sabre wiggle, or fit a gyro!  Mine is ok much of the time but if there is any wind or turbulence it sets it off and the model doesn't damp it out before the next gust starts the next wiggle, so the net effect can be a continuous fishtailing/dutch rolling in some conditions and speeds.

STORM

I've got used to that with the L39 Harry.

Alex48

The large F86 I did had a twist and turn on the nose but only the oleo cylinder rotated not the housing so you could attach linkages for the front gear door.  It was a clever arrangement and the folding front door was just hinged normally with two small springs either side which folded the door up when open.  Once the gear was retracted the force of the retraction pulled the door flat with the fuselage.

I've got a selection of small springs Gary, if you PM me your address I'll send you an assortmen.
The Little Jet Company
www.facebook.com/TheLittleJetCompany

STORM


STORM

Must bring this thread up to date, had a bad cold for three weeks over Xmas so didn't get too much done but today she's virtually finished.

Also managed to aquire some booms and wings for the Elan so I have been busy putting them together.

Got the scales out this morning, auw dry is 11.26 Kg, nearly 25 lbs! Heavier than I wanted but do you all think it will be ok?, turbine is JetCat P80SE with 22 lbs thrust.

Happy New Year to all!

pylon²

She will be a pussycat. Look forward to the pics. Hope to see you at Barkston Warbirds.
Richard.

STORM

Hi mate, not sure I can "Warbird" it, it's supposed to be an display aircraft, at least it was in the 50's.  ;D
I have enjoyed my first couple of Barkston WB's so much I don't think I would like to miss one now!
I didn't say thank you on the forum as I preferred to do it in person before I left.
It always seems to run and police itself, that to me shows great organisation, you and the B lads should be rightly proud!
I am attempting to join you,
Happy New Year and better luck in 2012,
Gary.
p.s. Hope you are right about the pussy cat bit!

STORM

Difficult to remember where I was now after a lay off.
Final assy was being delayed by me not being too happy with the elevator pushrods binding a bit, this meant that the thrust tube was being delayed which meant the bypass and engine etc. etc. etc.
So yesterday I went for it.
Flap and aileron hinges were connected and then the wings slid on to check clearance on the fuse root which I knew would present binding problems because of the swept back trailing edge.

STORM

Sure enough a problem, fouling. Rather than releive material from the flaps I opted to remove it from the fuse root.
Not pretty but won't be noticable except when fully flapped on the ground. Bit like me really!  ;D

STORM

After sorting the elevators I worked on the bypass set up finally gluing the mounts and packers in.

STORM

An observation window was the cut for the air trap to be seen, thanks Alex!
All ecu connections were made and the intake duct installed for hopefully the last time.

STORM

Before the pipe could be fitted I had to fabricate a rear support former, this was originally going to be made as a simple liteply ring but then I realised that unused air needed to be able to escape out the rear fuselage so I modified it before fitting.
The inside diameter was a bit tricky to measure because the pipe tapers but trial and error overcame the problem.

STORM

Before fitting the pipe I checked my notes and realised that I needed to support the extension cables to the top of the fuselage, a simple gadget was made and cyno tacked then epoxied in.

STORM

While that was drying I did some serious fettling to the wing tank support pods which will live permanently on the wings as it makes them a little easier to handle (something to grab hold of!)
The top and bottom surfaces were not square and the profile to the wing was bad.
These did not fit well from the factory but they do now.

STORM

The pipe, bypass base and turbine was then installed and fuel supply from the valves and turbine cables connected.

STORM

The last major item left was the top tray carrying the powerbox etc. When trying to fit this and connect the servo cables I found that the plate fouled the connection route for the turbine power supply so a small chunk was removed from the plate.

STORM

The plate was then attached and all servo cables connected, a little remapping of the SRS output was required to keep it as neat as possible but I am pleased with the final result as I may need to get at the box for programming etc. later.

STORM

The thoughtfully supplied "carrying handle" was then fitted.  ;D
I'll probably give that a lick of paint sometime.

STORM

The satellites were then connected for final rc and turbine programming so now almost all that remains is to permanently install receivers and ecu battery. I have deliberately left the lipo untill last for cg reasons and of course if it ever does decide to catch fire it will be accessible and quickly removable.

The one big worry is the cg, have to wait for a nice day to get her outside on the cradle and fully assembled. I always worry about this but usually the cg works out well, almost of the heavy stuff is at the front so it's a big fingers crossed because if it is out it's going to be a real pain to rip it apart again to get at the stuff in the lower region (read bowels) to move it about, I hope that I will not need any extra ballast in the front, there is room right in the nose but at an all up weight of nearly 25 lbs dry I could do without that problem!

Another worry is that I heard that when the gear is up it fouls the bypass so that was checked next.

Phew! Close!

STORM

So, there we have it, from having bits lying around everywhere suddenly in one day we have a Sabre!

As mentioned, cg next and we find out how well or not it's been put together. Due to the design it's going to be pretty much impossible to see if we have any fuel leaks as everything is buried away now. Air system has been checked and everything seems to work ok with no leaks yet.

Just a few things to tidy up, still a little work to do on the front gear door as my first attempt is not to my liking yet and then we are ready for ground/system tests.

I'll post some pics when she is on her feet and update on future developments, test flight etc.

Thanks to you that have been following the thread, I hope it will help someone in the future as I am sure this model will look nice assembled and hopefully fly well also.

A very Happy New Year to you all,

Gary.

selleri

Happy new year mate, looking good, like the innards!
Sverrir  - Icelandic Volcano Yeti - RCMF Tech Team

STORM

Does that mean you don't like the outside?  ;D

selleri

Well now that you've brought it up...       :nananana:
Sverrir  - Icelandic Volcano Yeti - RCMF Tech Team

STORM

I wanted to finalise this thing today but not in a gale and pouring rain so got permission  ::) to assemble in the house for cg, final radio setup etc.

A few pics while it's in one piece.

STORM


xairflyer

Dont like it, horrible  ;D maybe that should be  :'( I want one  :'(

Looks great Gary cant say the same for that chap sitting behind it  ;D