phantom_najd

My Feedback: (2)

I built two Ultra Flashes and in both I had no problems with the provided L brackets servo mounts. I however have noticed that the L brackets come with different hole locations in each arm of the bracket. So one arm of the L bracket would need to go against the servo and the other arm against the carbon cover. the difference is very small in the locations of the holes so the servos will install okay on either. When you install the servo on its arm it will sit flush on the table while when you install the servo on the wrong arm it will be raised and the brackets wont align with the cover's holes.

Azzam

Steve N.

Thanks for that Azzan. I do wonder if that might have been my problem. But I had a look for that and didn't find an improvement. Don't deny that it could have been me and my older eyes :-)

Steve.

737Driver

That's a 2 part question.

1. Referring to covers for BOTH aileron/flap servos. As you see in my photo, I split the cover in half to access either gear, or flap/aileron servos. Had zero problems mounting servos to wood support, easy peasy

2. Referring to elevator servos metal mount brackets. Yes in fact, when screwing all 4 screws into the metal, invariably 1 screw would give me a "hard" time and I would have "coax" it into place. It sure seemed that it would cross thread, but in my mind, that bad boy ain't come'n out till I said it was time to come out. Now, as far as all 4 screws securing the elevator hatch down, they all have to be aligned perfectly so that when you tighten all 4 down, 1 doesn't bind the other causing the panel to not pull flush with the skin. What I ended up doing for ALL panel screws was if one was binding the others, I would widen 1 or 2 holes a tiny bit so that the screws wouldn't bind all the others. It's more of attention to detail than anything else as far as getting your panels to "flush" with wing skin, horizontal stab skin. My sincere hope is that I didn't thoroughly confuse you!!!!

737Driver

If you look at post #5188, photo #2, left side of photo, upper right corner screw, you'll see that I had to oblong the cover screw off center a tad so that the cover wouldn't buckle when all cover screws were tightened. Before I did that, when I would tighten all 4 screws, the leading edge of that panel would buckle up a tad, not a big deal in my mind, just attention to detail is all.

tellmic

I have build two UFs and many other Carf jets. Yes there is some normal small tolerance in the position of the holes. What I do is drill the holes in the carbon panel 0,5mm larger and there is no problem anymore the get the screws in place.
The carbon panel should be sanded at the inner edge so you will get a bevel, this improves a flush fit.

have fun building and flying your super sports jet!

Michel

Steve N.

Nope,,, you didn't confuse me Tom. The wing hasn't been an issue for me because I haven't tackled it yet. I just wanted to install the elevator servos before going to the Princeton Rally.
It sounds like you had a similar issue with the aluminum brackets. I could do it, and they would have held just fine,,, but I didn't like it because it wasn't right.
I sanded the edges of the covers (outside and bevel) as Michel suggested,,, and the lay flat and fit like a glove.
Steve

737Driver

That's a great idea Michel to bevel the inside of the carbon cover. I'll give that a try when I button up the aileron/flap servo cover. Yeah those aluminum L brackets weren't very friendly to work with, but I got them to fit the servo with a little effort, didn't think about drilling them out. This is my second Flash, the first one I didn't build so it's a learning build for me

tellmic

My "speedy carrot" custom McLaren sceme.

737Driver

Damn Tellmic, that thing looks fast, even for a still photo! Man I can't wait to get my Ultra in the air.

Steve N.

Yeah,,,, Damn Tellmic. That's an awesome scheme, and awesome pics. If I didn't have one,,, I'd want to go out and get one.

Steve

FMRR

Hi Steve, Thanks for the link. Not sure if I want that footing glued just to the skin. Like to attached it to the aft spar,upper and lower skin on the forward end... this way both the upper and lower skin support it...sandwich box... may be over kill , but not sure about flap servo and holder flexing on the upper skin alone... what do you think ?

Steve N.

You have a point about possible flexing, but that's one of the reasons I wasn't sure if the mod was a good idea. I'm certainly not an expert, but if you want my opinion, I'd suggest that you just stay with Carf's flap system. I understand it's a bit of a pain to set up at first,,, but has worked well in countless UFs before us. (Just my opinion)
Steve

FMRR

Duly noted, nothing wrong with UF design and we'll proven. May go with the original design as intended or modify it. When I get to that point I'll decide. I'm Airframe Powerplant mechanic so I like easy access to rigging and inspections. If Dave can share how the wing is actually layed up that would be helpful. Wing skins are very strong well designed and fabricated...quality # 1. Appears to me the skins ( Wing Planks ) are the primary structure, monocoque design or semi monocoque. They would have no problem supporting the flap box support.... Imho.

Dave Wilshere

In the UK there are lots of UF models, we have always done the servo mount as stock since it works. Never struggled connecting the linkage. I guess its understanding the mechanics and that the hinge line to servo position WILL vary wing to wing and also the control horn to hinge line. Its just not possible to jig that the same. People measure flap travel to the TE, I never do as the hinge line to TE can vary depending how they are cut/released. I stand over the nose and line the top surface take off and landing positions.

The wing layup will take a plate for the flap, the outer skin is two layers of cloth and inner a single layer. The UF wing is tough, rigid and almost certainly the strongest on any sports jet.
The wing spar is Carbon capped, early Flashes had plywood spars, first UF's had glass skinned balsa and now glass skinned PVC type foam.

FMRR

Thanks Dave that's helps a lot. Two ply outside, one ply inside seperated by PVC foam... assuming each ply minimum 6 oz.... that would be strong enough to Hysol sevo mount plate to upper skin only....then the servo mount Steve recommended will work with out the extra work. That makes the modification much simpler. When I get to that point I'll decide. Dave you really know these jets inside and out. Thanks gentleman Cheers.��

737Driver

Wing is officially finished! Let me just go on record and say that the flap linkage was a ROYAL PITA!!!!! Once setup though, set it and forget it! Works fine, lasts long time. The only thing left is to glue the strut doors on..

I have a question??????

Do you trim the door so that IF the the strut twists in the trunion, and the gear retracts, one side of the door won't bind in the strut/leg cutout?

or......

leave the strut door alone and hope it sits flush with the bottom skin of the wing when the gear retracts, AND the strut just happens to twist in the trunion and POPS the door off during the retract cycle?

man I sure hope I didn't confuse everyone and someone can chime in. Thanks!

FMRR

Hi Tom, I just read your PM and sent you a message. Sorry the for slow response...just very busy.

Dave Wilshere

Last weekend I was in Aberdeen (Scotland) for the annual Heli Nationals. Local Stewart McCallum was demoing his UF, JetCat P-140 Rxi-Brushless, All JR.
Photos by Jim Selkirk

JP-1

A few pictures of D.W.s Ultra Flash at RAF Whyton, (Two years ago) some slow fly-bys for the camera

Alistair

Steve N.

Hey Tom,
It looks as though you haven't got an answer yet... Being that mine isn't built yet, I don't have any operational experience with the strut door. However,,, having read through this entire thread, I believe that most of the guys aren't bothering to install them as they are more cosmetic than serving any function. I believe that those who have installed them, do so with light bond (like a few drops of CA?) rather than a solid/permanent mount with Hysol. That way, if they do end up binding, they'll just pop off rather than cause any damage.

737Driver

Steve N.


Many thanks for the reply. After talking it over with a fellow Flash flyer, I believe I'm going to trim the door to fit inside of the strut cutout in the wing. That way, IF the strut twists in the trunion, the door will slip inside the cutout, even if it's twisted a bit. I had that door on my previous Classic Flash, didn't crash it!!, and kinda like that it covered that part of the strut. I am leaving those silly pre-fab'd plastic pieces that fit inside the strut cut out, out!!!! They don't fit very well, more of a PITA than it's worth.

Thanks for the reply!!!

Tom

Steve N.

I would appreciate it if anyone who is running a Merlin-140XBL (with a full bypass) could offer me a little advice...

1) What is the optimal distance (for temp vs thrust) that the aft end of the exhaust cone should be from the front of the inner pipe? I believe that a while back Dave W. mentioned 22-25 mm. But I'm not sure if that was in reference to a big block or if that would also apply to a 140 size.

2) In that the fuel line and turbine cable exit the top of the Merlin, is there enough room between the top of the turbine and the bypass/fuselage to run the line/cable out without kinking,,, or does the turbine have to be rotated? If so,,, how far can it be rotated without it affecting the start-up with the burner out of position?

And while I'm asking questions...

3) I don't recall anyone mentioning the use of BVM Heat Shield, Other than the inside of the bypass, is there anywhere else that I should be using it? ie: the top of the fuse above the aft 1/2 of the turbine,,, former #6,,, and/or the inside of the carbon bellmouth?

Thanks in advance,
Steve

Steve N.

No problemo Tom. I didn't plan on installing them, but after what you just said, I may reconsider. I'll see how the frustration level is by the time I get to that point (lol)

Thanks,
Steve

737Driver

I'll take a picture of my doors when I get them installed

DrV

My Feedback: (2)

Hi Steve.

I have an M140xbl in my UF. I won't be able to measure to tell you for sure since I'm out of the country now. But since the turbine is within a bypass it does not matter much. I usually use 5/8"-3/4" as a general rule from the end of the cone to the front of the inner pipe when running without a bypass. 22-25mm should be just fine also.

As as far as the MPX cable entering the turbine. If you have the plane upside down with the wing off and looking from front of the plane to the back, my MPX cable is positioned at about 8 o'clock position. I have made a slot within the bypass to accommodate the wire.

I used the bvm ceramic heat paste within the last 1/3 of the hot section of the bypass top and bottom and also within the carbon cone that connects to the exhaust tube.

Hope this helps.