Had 4 at the field today, each of us with at least 5-6 flights.. good day at the field!

Setting up my Diablo and have a few questions.

The manual calls for 7mm "elevator mix" @ full flaps. I am assuming that means down-elevator, but can anyone confirm?

The elevator rates and expo for normal flying + T/O and landings seem excessive in the manual (55mm and 65% expo). Would around 25 mm and 25-30% expo feel more linear and natural?
I see someone mentions tip stalls on landings and recover from 3D maneouvers. Would a bit spoiler mix (ail up) with flaps and elevator to spoiler mix help on that?

Are you messing at the leading edge or trailing edge of the elevator? I’m at about 45mm and 30% expo for all flight conditions (flight, TO, land 3D), measured at the trailing edge.

As far as tip stalls go, just remember that it’s a 2m jet and don’t slam the ailerons when going slow. It slows down very fast due to the massive intakes and low momentum. Always keep the nose pointing down when at idle and you’ll never have a problem.

Diablo needs understanding. If you want to 3-D then yes large movements are the norm, but normal aerobatics can be flown with a fraction of the movement. +/-20mm elevator movement. If you need high expo to dampen the large movements you will get a very un linear feel to the elevator. Crow is NOT needed, it has a tonne of drag, which gets people into trouble since it Slows up really quickly once the nose is allowed to come up…presenting those huge flaps to the airflow.
Rudder throw should also be limited, I needs very little and large movements will get you into trouble…

Yes, down elevator with takeoff and full flap, remember the balance goes back as the tank empties, so set the landing down towards the end of the flight.

Just building my diablo

is it normal to trim the servo horn slots?

I had to dremel out some of of the servo holders to get servos in and on the tailrons/elevators I had to dremel out to get the servos in

also had to cut/trim control rods to get correct length

not an issue just manual mentions not of this …?

Yes, normal to open up the slots for the servo arms.

Yes, depending on the servo you use, you may need to open up the servo pockets slightly.

Yes, cut your linkages to the correct length.

Are the elevator clevis clips a CARF only thing or is there another source for spares. I am pretty sure I am go to lose one at some point.

Dan

CARF have them as spares, ask your CARF Rep and I’m sure they will sort you out.
I have carried spares for 2 1/2 years..still not needed!

That is the surest way to not need them is to have spares.

I knew you were going to say that as I posted 😁

Hi guys, I’m starting to push my Diablo more and have been doing some 3D maneuvers with it such as spins and harriers. I’m curious about the best approach to recover from 3D maneuvers. My default recovery is to point the nose done and apply power to get airflow over the surfaces. However, sometimes during spins, it’s hard to get the nose down. It is safe to apply full throttle to punch out even if the nose is not pointing down? Wondering if I can pick up from tips from you all. Thanks.

As long as you can accelerate the wing into flying again, adding full power is the normal approach. Other than climbing where power to weight is the deciding factor, I would not worry if it is upright or inverted, just accelerate out and fly the aircraft.

The only safe way to exit any of the 3D maneuvers is with full throttle. Never just point the nose down and hope it works. Always full throttle and keep the nose level with the vector. After 10 seconds it’ll be flying again and you can take the gyro and vector out of 3D mode.

Guys, I just started flying 3D with Diablo, had other 3d EDFs before, and had a couple of sudden pitch up on take off. I have 220Rxi in mine and previous owner had put in a fuel bag. I noticed fuel bag extremely close to turbine. So last week on my second flight a sudden pitch up on take off at 70% power, I pushed elevator and reduced my power and all of sudden I had a flame out. I am hypothesizing that the fuel in the bag conformed to the turbine intake and caused suffocation /compressor stall.
Nonetheless I need to fix the fuse and will go back to regular tank and will reduce the elevator to 20mm. Is it possible that my TV is not trimmed (to the thrust line of tube, how best to line up the TV to tube?Could the plane be too nose heavy? any other suggestions to avoid sudden pitch up (Obviously not pulling elevator too hard, I realize, I just nearly touch the elevator and it lifts off.).

Also, in the manual it recommends to put the overflow (tank vent) near the rear of the fuse. Can you tell me why is that recommended. Can I just put it right under the tank?

Thanks
Jason

The jump on takeoff is because the nose leg is too short ( no spacers) or too soft, original spring…probably both.
Also I guess you hold the brakes and open the power? Bad tendency also compresses the nose leg.

Flame out could be bag, but sounds like it is not mounted properly, it should be retained from sliding.

DW

thanks Dave, I do not hold break and open power, I slowly gain speed and with this plane I would only go to 75% power and it would lift off easily. My very first flight it did sudden nose up and when I reduced the elevator travel it wouldn't do it after that. However I reset the elevator to factory for other reasons. Hence I am going to set it back to 20mm as recommended here. However, the nose strut is just as it comes, no changes were made to it. Does it need to be moodified? do I need to change springs? do I need to make sure it stays fully open? and do I need spacers? how much?
Any comments regarding the vent?

Thanks
Jason

For this reason, I mounted my nose retract with the retract wings on the bottom of the retract mount. I moved the blind nuts to the top. The front bulkhead needed to be Dremeled for the steering. Canopy needs a little Dremel sanding, because the wheel now extends further forward when it is retracted. This helps extend the nose wheel to get rid of the negative ground incidence. Rotation is more stable.

After the first kits CARF added spacers, a longer steering pin and a stiffer spring inside the nose leg.
I still additionally add 3/32 Tygon inside the spring to keep the nose leg as stiff as possible, even with my P-220 I don’t have a problem.

can you post pictures of how the fuel bag was mounted? It should not be any closer to the turbine than a regular fuel tank would be.

Haven't flown mine so much yet, but never noticed any pitch up after take off. But didn't try to rotate too early and TV is is OFF in T/O and landing mode (but TV gyro stays ON to dampen any unwanted pitching).

About trimming and centering the TV, i didn't find it easy as its tapered and the back end is not cut accurate enough to use a angle meter.

But, here is how i done it on other planes after eye balling the line up first.
Fly straight and level and trim the plane at a high cruise speed. Then chop the throttle to idle. If the plane starts to climb the TV is too much down. If it starts to dive, its too high.
To center left or right, fly past yourself in low pass, a couple of hundred meters after passing yourself pull into vertical and release the sticks. You will see if it plane wants to go left or right.
My TV elevator axis was good, but it pulled a bit left in verticals so have adjusted that before next flight.

What surface on the fuse can be used as a reference plane to check TV pipe thrust line?
I don't have a close up shot of the fuel bag to show, but it was butt against the FOD screen. I am thinking it conformed to the FOD on take off roll.

Here is a shot of the plane just before taking off. does it look like it has negative incidence? Seems pretty level to me



Thanks
Jason

Hey Jason,

As you said, it’s difficult to tell if there is negative incidence. And, yes, yours looks level, but 1 degree of down incidence is difficult to detect without an incidence meter. And, even -1 degree will make a difference, especially on a high performance jet.

I don’t have TV, so I’m sorry that I don’t know the answer. With others I have helped with their different TV jets. I learned that the VT pipe changes when heated. It can be trimmed zero-zero when the engine isn’t running. After the starts and heats the pipe, the TV pipe will have moved a couple degrees of either up-down or left and right, and even both directions. So trim it hot standing over the tail and looking from the side.

If you’re familiar with Robart’s jeweled incidence meter. It can be used to see if the jet has negative incidence. It is used on the wing. Moving the retract to the other side of the mount was the last thing I did after making sure the W/B was where I wanted it to be. I use the knife edge to trim the balance. I want it to be neutral with no tuck or pull, and no mixes. Because most jets start off nose heavy, it pulls to the canopy in knife edge. I move batteries aft until it tracks true and straight without any mixes. After I did that, it still would jump off the ground. Because of another jet I had experienced the negative incidence, is how I SWAG the Diablo has negative incidence. Moving the retract to the other side of the mount is how I solved it. I didn’t want to buy a longer nose strut.

There is a chance this shot is after the nose leg started to uncompress. It looks normal from the sit position.

No need to buy a longer leg, CARF would have supplied the longer pin and spacers. Anyone with an early kit was able to request them.

Dave

Can someone please post a picture of the front retract installation. My steering arm hits the front former.

Have you got the two spacers? One above the steering arm, one below to extend the leg?