All-New Freewing PJ50 Twin 70mm EDF Jet - Official Thread

[GliderGuy]

The First PJ50T in Mexico

Most excellent! Congratulations!

Please consider adding a gyro. It flies a lot better with a gyro during landings. You may have difficulty landing without a gyro when the wind is blowing.


https://www.motionrc.com/products/ea...SABEgJX9PD_BwE

-GG

[jasmith41]

I'm planning on using a Spektrum AR637T rx in my PJ50. Does anyone have any suggestions / advice / input to share regarding this plan? I'm still very much a novice so SAFE will be on most if not all of the time while I'm flying...

Is there anything I should be aware of or cautious of with this set-up...?

Please share your thoughts - all are welcome and appreciated as usual...

[GliderGuy]

I'm planning on using a Spektrum AR637T rx in my PJ50. Does anyone have any suggestions / advice / input to share regarding this plan? I'm still very much a novice so SAFE will be on most if not all of the time while I'm flying...

Is there anything I should be aware of or cautious of with this set-up...?

Please share your thoughts - all are welcome and appreciated as usual...

Whatever your final setup is, BE SURE it includes a gyro. Otherwise, you will have issues landing it with anything over a light wind. The Dutch roll induced by gusts is problematic.

After I installed a gyro, she’s my go-to bird on windy days. She’s my all-around favorite bird.

I have no added comments on your radio set-up.

-GG

[xviper]

I'm planning on using a Spektrum AR637T rx in my PJ50. Does anyone have any suggestions / advice / input to share regarding this plan? I'm still very much a novice so SAFE will be on most if not all of the time while I'm flying...

Is there anything I should be aware of or cautious of with this set-up...?

Please share your thoughts - all are welcome and appreciated as usual...

The 637T is quite effective and is not too bad for forward programming. "SAFE" is simply a feature that limits your roll and pitch angle when you crank on the sticks and it self levels when you let go of the sticks. I use it primarily for emergency recovery and on some planes, I use it only "on final" as it helps to keep the plane straight and lined up weill with the runway. On the PJ, I don't use SAFE at all as I've never had it "get away" from me.
As for the gains and priorities, leave priority at the default 160. If you're not sure about what gains to use on each axis, I suggest you go with something like 40/45/50 (AIL, ELE, RUD) and make them "adjustable" and assign that to the rotary knob and begin with the knob at the mid-point (ie, 50% or 20/23/25)) and gradually increase until you see some oscillation. On this plane you should be able to get the knob to about 80% before anything can be seen. Then note the knob position for all future flights (mark it on the underside of the battery hatch.
Assign a switch that handy to you for SAFE and use the default angle limits and gains for it. That usually works quite well for most planes. ALWAYS test the gyro response for SAFE and for AS3X while on the ground. Remember, you know that SAFE is incorporated into the programming as soon as you hook up the plane's battery as it will twitch the control surfaces twice. Note the direction the control surfaces move to counter the movement of the plane. Roll and pitch the plane and hold it there and the control surface will react and stay.
AS3X can only be tested after you blip the throttle to at least about 1/3. Then you can pick up the plane and move it quickly "off level" and hold it. Watch and see the direction of movement and that the control surface returns to neutral at the end of the tilt.

[jasmith41]

xviper Thanks Viper - you confirmed what I've been thinking this whole time about this approach. I've set-up the FW birds I have now with either the 6 or 8 ch Spektrum AS3X / SAFE rx - haven't flown all of them yet, but feel better about the plan...

I guess i just wanted to make sure there wasn't something inherently incompatible between the two (FW planes w/SAFE...). Thanks again.

[ColtPilot]

Work in progress. Wing painted and needs to dry. All Callie Graphics. This B1RD is turning out really well.

[ColtPilot]

https://photos.app.goo.gl/E9gfZpCmMngE5Lwe9

lights camera action.

[ColtPilot]

https://youtu.be/B5vDTAOAQFg

Took the PJ-50 to the US Coast Guard Air Station Detroit. The guys there loved the jet.

[ColtPilot]

This biz jet/Coast Guard livery turned out fantastic. Hope to maiden tomorrow.

[Twowingtj]

Good luck!

[GliderGuy]

Always looking for “better ways” to do cosmetic repairs….especially foam cell boundary cracks in areas under stress.

The PJ-50’s wings are just now showing stress cracks on the wing top skin after a lot of flying + aerobatics. The PJ-50 wings resisted cracking far longer than the AL-37 wings (which have the added stress of the nacelles).

I’ve tried, without great success, in the past to use various fillers, but the cracks return.

So…trying a new approach and experimenting with UV curing glue = Bondic.

1) Cut along the crack to widen it a bit…1 mm or so and almost down through the top skin thickness
2) Filled the crack less than full with Bondic and cured it with UV light
3) Finished filling the crack to level with the top of the skin with another layer of Bondic and cured it
4) Sanded smooth, painted, then added a coat of Minwax One Coat Polyurethane UV protectant

Now to see how this fix holds up. The Bondic bonds very strong to the foam. We’ll see after more flying + aerobatics.

-GG

[xviper]

The PJ-50’s wings are just now showing stress cracks on the wing top skin after a lot of flying + aerobatics. The PJ-50 wings resisted cracking far longer than the AL-37 wings (which have the added stress of the nacelles).

Your AL had many hundreds of flights. How many on the PJ before the wing cracks showed?

[GliderGuy]

Estimated….around 1000 flights

Received in early 2022

Here’s the math / probably very close to reality, but it is ONLY an estimate based on my flying habit

365 days x 0.7 days flown = 256 days
30% of those days were PJ-50 flight days = 77 days flown
When flown = 10 flights minimum (often 20 flights)

So 77 x 10 = 770 flights
77 x 20 = 1540 flights

1000 flights won’t miss it too far. 😃 Only recently started to show the top skin cracks. I am impressed by this wing!

-GG

[xviper]

Holy Moly, GG! 1000 flights! My most flown planes are my sailplanes and I might get 60 flights a year on any single one of them (I have 3, about to be reduced to 2). My other planes, even my favorites ones, might get 30 flights in a whole season. My least favorites one, even though I still like them, might get 4.

[GliderGuy]

Yepper, even if my estimate is 50% too great, that still speaks well for the PJ-50 wing design. Most folks will get years of flying before the cracks appear.

Noteworthy, I don’t baby her. She’s flown fast and with loops, inverted, snap rolls and spins (sorta…not a great spin bird). Also, she’s my go-to “windy day” bird, so lots of fast flying thru rough/gusty air that makes the wings flex. Windy day bird = only after a gyro was installed.

Also, this is a stock wing. No mods or internal reinforcement done.

-GG

[GliderGuy]

SUCCESS!!! The Bondic UV-cure glue repair of the wing’s top skin, foam cell boundary stress cracks passed test # 1 (see my earlier post above).

Made 10 flights and didn’t baby her. Aerobatics and high speed flying. Neither the left or right wing’s cracks opened back up.

Time and more flights will tell, but the initial results look VERY promising!

-GG

[GliderGuy]

Update to my post 491….almost 2 months later and several hundred more PJ-50 flights.

The Bondic held up, but the amount of flexing the wings still do caused the paint to crack. UGH and UGLY! The crack in both wing tops is about 1/4 the way to the tip and both cracks run chord-wise….almost from leading to trailing edge.

Back to the drawing board.

This time I Dremeled out the cracked paint and then Dremeled in span-wise trenches 90 degrees to the crack. Then I epoxied in some mini spars/stiffeners made from a carbon fiber sheet.

Filled, sanded, painted. Looks like new. The stiffness and resistance to flexing is vastly superior than to the Bondic-only prior repair attempt.

I’m betting the top wing paint won’t crack again. Not in this area, anyway.

The following visually depict the above and show the final results before I overcoat with polyurethane.

When I wear this bird out, the next PJ-50 will get an additional carbon fiber spar glued to the inside of the top skin like my AL37. That’s a real solution.

The designers of the PJ-50 weren’t counting on a thousand or more flights done with aerobatic flying.
-GG

[NickThePilot]

I am planning on purchasing this jet. I am fine with fast flight, but does anybody know if this jet can takeoff and fly and somewhat slow speeds? If so, how slow? Thanks!

[GliderGuy]

Hi Nick….

Somewhat of a subjective question and depends upon pilot skill level.

First, plan on buying a gyro with the bird. Before I installed a gyro, I was about ready to stop flying her. Any gust on landing can start a Dutch roll action that makes landings DIFFICULT. After I installed a gyro, she is a tamed animal. EASY to land.

Second, adjust aileron linkages to raise each aileron up so that with neutral stick, each aileron is about 5 mm up. This helps kill the Dutch roll as well because it reduces the tip stall.

My experience level would be classified as HIGH, so take this into consideration. I have over 1000 flights on the PJ-50…..no kidding! The below is stated from a COME IN COMFORTABLY…not on the hairy edge of a stall.

For short fields…which is probably why you are asking your question: She is a floater…low drag bird. She will glide FOREVER if you are fast on approach. You gotta be prepared to kill the power very early on base leg, or come in very low. Even with full flaps….and do plan on using full flaps for short fields. WITH A GYRO and 60% gain,!she has no bad flight characteristics at slow speed. It is possible to land slow. But, if you operate on hard pavement, give yourself 250+ feet to land and stop in a zero wind condition. If your hard runway is wide enough to make a wide J turn as she slows down, you can get by with 150 ft to land and slow down plus another 100 ft of roll to do the wide J turn at the end. I measured where I fly via Google Earth for these numbers.

She flies well in STRONG wind conditions WITH THE GYRO. In a good wind, you can get her stopped much shorter.

As with any slow flying bird, a stall and fall is always a concern. Your skill level will determine “how slow you can go”.

WITH A GYRO, she is my all-around favorite bird to fly in all types of wind and turbulence conditions.

Without a gyro, I was ready to hang her from the ceiling as a display-only bird. Especially in windy/turbulent flying conditions. Calmer days = Just fine without a gyro….but only on calmer no gust days.

Take-offs are VERY short. She has a TON of power, accelerates fast and with 1/2 flap is airborne after a very short run.

Slow flight with gear down and 1/2 flaps…nice and stable WITH A GYRO!

-GG

[GliderGuy]

Reference post 497 above…about the top of the wing. Now, for the bottom of the wing.

I noticed where the bottom wing section pieces fit together within about 6 inches of the fuselage the sections were beginning to develop a case of the “spread apart itis” under a positive G load.

So I added several mini carbon sheet spars all along the wing piece joints to stop the spreading under load. I added 6 mini spars sunk into the foam skin from near the leading edge back to near the flap. Did this to both wings.

See drawing below.

I flew her this morning and had to make a little aileron trim adjustment. Apparently the wing had been slightly twisting under load. She’s tight now and solid. Filled, sanded, painted…can’t see them.

Eventually, I am going to wear this bird out. She’s my all around favorite EDF, so she gets a ton of stressful fast and aerobatic flying which is wearing on her. And all this flying, only one aileron servo has needed replacement. Truly amazing for these tiny servo motors.

-GG