MorseAircraftDevelopment

Tom, give me a shout and if you can send me some pictures. 907-317-6056. I will contact Tony after viewing your photos. I want to see if it looks like you had an unknown hot start or if it is heat over time. Because we have been running even bigger turbines in it and have not had this issue.

dmattmul

Kim, you will need down mix for the elevator. I have 12% down but it depends on the throws set up.

Tip22v

After discussing this with Jordan we think I have the turbine mounted to close to the exhaust tube, which would restrict the exhaust pressure from drawing cool air around the turbine.
I used Jordan's recommended stick method for measuring the distance and it was 35mm, not 25mm as I thought. I moved it out to 40mm, I will try it this weekend. Big thanks to Jordan for the help. Tony from Pilot has also contacted me so it's very encouraging to see the manufacturer being responsive to these kinds of issues.

Kim Couturier

My Feedback: (120)

That's interesting as the instructions specifically say to put up elevator mix in....going to try with no mix and see what happens...

Helijet

Put a number of flights on the Dolphin this weekend. Thanks Tom for the measurements - they were helpful. I found them to be quite comfortable.
A couple of things I noted. My bird landed best with 35 degrees of flap and 3/8" crow mix. I found that NO elevator mix was required. In fact BE VERY CAREFUL when using any elevator mix with down flap as this bird is very sensitive to elevator inputs with flap set. The bird definitely has a little tail wiggle in flight and was more pronounced with wind. On the 5th flight I put in the iGyro 3E and dialed it in. The Dolphin wiggle immediately went away and the bird was locked in the entire flight. In fact, it was an absolute pleasure to fly. Sloooooow rolls, perfectly easy loops and solid approaches to bounce less landings were the order of the day! I found +47 on rate to be perfect. I like the overall L39 impression in the air. The bird handles well on the ground and takes off with ease. I am very impressed with the value of this aircraft. It is made even better with a a little 3axis gyro help. On a final note...I found the power from the KT 140 to be the perfect combination for this airframe ( trainer wings )

Dean W..

Tip22v

I'm glad to hear everything went well. Did you get a chance to clock you top speed? The max I've been able to get on radar is 134, others are getting 150ish so im just curious. Also, what does "+47 on rate mean"? Is that the preferred approach speed? Thanks for the info on the igyro and the wiggle, I have one sitting in my shop and based on your findings I will get that installed. Regarding the elevator mix I mixed in the exact amount recommended by pilot but with 30 degrees instead of 38 degrees of down flap and the aircraft stays perfectly level when the flaps are deployed (no ballooning). On earlier flights I found that aircraft pitched just a very slight bit when the flaps were set to 38 degrees down. After reviewing the video extensively I believe the slight pitch up was caused because I was not properly slowing the aircraft before deploying the flaps.

Anyway, congrats on a successful first weekend!

Helijet

Hi Tom

The max speed was around the 140 mark. I think it could get a little faster but not much. The + 47 is the number that I found in the rate setting to have the best effect..no oscillations at cruise speed. It seems to work well all around. Did not use the heading hold yet. In full dirty with crow the plane is very stable and locked in. It took me a few flights to figure out the flap / elevator setting and I found that virtually no elevator trim was needed. My aircraft balances exactly on the recommended cg with no extra weight. I also check for any heat damage and the area around the engine is perfect, so I suspect a position issue in your case.
I did a couple of stalls and the plane just dropped the nose but I wonder what it would do in a spin. We were thinking that tail was awfully close to wing trailing edge...thinking the rudder may be blanked out. Maybe I am just over thinking it...lol

Anyone spin it yet...???

Tip22v

Ah, rate on the gyro, I should have figured that out, thanks for the clarification. I think I will try the crow settings you listed after I get the gyro dialed in. I have to send my K-140 back to Kingtech as it started leaking again so it will be a couple of weeks at least before I can fly it again.

Kim Couturier

My Feedback: (120)

Well guys, a sad end to my Dolphin! Both initial flights, the jet rotated by itself....it was suggested I may have had it tail heavy. Checked it, and it was right on according to the instructions. Went to the northwest Mi. Jet rally in Baldwin today....first flight....take off run was very good, jet rotated smoother...it got about 2 feet off the ground, and rolled violently left, and piled into the ground. We have 2 videos of the take off, and, quite frankly, I am baffled. I had plenty of airspeed, made a good transition......everyone who looked at it agreed there was no reason for the jet to go down like it did!, Very frustrated....Jordan, any way Chief might help me out some way with a replacement? Not going to hold my breath!

MorseAircraftDevelopment

Kim, very disappoint to hear the news. Before any speculation starts on the cause of the crash is there anyway I might see the videos? Ate the videos of good quality? I would really like to look at them to see if there is anything that stands out to me. For a plane to roll hard on takeoff without anything being changed from the last flights leads in a few different directions. If you would like to call me I am available all the time. My number is 997-417-6056, I would like to talk to you about what your general set up was and get your take on what you think it was. Please contact me when you have time. As far as Chief goes... I couldn't say, I am not associated with Dana. I simply try to help guys with this plane that I reviewed and update you guys when tony gives me new info.

Tip22v

Sorry to hear about your Dolphin. I would also like to see the video to see if my jet exhibits any of the same behaviors. Ive got mine setup to be slightly nose heavy with a full tank of fuel and it does not rotate until I apply up elevator.

Kim Couturier

My Feedback: (120)

Don't know if I can get video. Was done by a spectator.....I suspect, after talking to Chief, that it was tail heavy......waiting to see about getting parts. Need a fuse, wing tube, vertical stab, and canopy.....

Tip22v

Jordan,
i just got my Xicoy weight and balance computer like the one you have, would you mind sharing your setup parameters for the Dolphin Jet? I want to be able to double check my measurements to make sure I've got the numbers right. Thx!

smaze17

My Feedback: (60)

Regarding the crash, is a radio problem totally out of the question? I know you mentioned that it was tail heavy but so tail heavy that the plane would violently snap like that? Has anyone considered a possible radio issue?

dmattmul

Here is the XyCoy readings on the trainer wing. I've been a little suspicious that this wing because it is more swept back might needs the CG further back. This tank is larger than the one provided and that might help. Sure sounds like it was tail heavy but radio issues could also be a problem. Does the fact that this airframe tends to need up elevator when flaps are out indicate anything? Mine definitely needed down elevator like almost every airframe I have flown.

dmattmul

Kim, noticed that you we went with a K140, it's about a pound heavier than my JC Cheetah. How much nose weight did you use? (If any) I'm assuming you did not have time to raise your gear? That would have made it worse. Also saw your jet was rotating on it's own, seems that might be telling you something. The new Xycoy is really great to have for these size planes. Without it took 3 adults and that was using my large 250 USD balancer.

Kim Couturier

My Feedback: (120)

I had about 3 1/2 ozs added to the nose. I couldn't get my batteries way up front, and I think that's why. You guys have all been great with your input. hoping to get replacement parts from Pilot so i can get it back together! K-140 is awesome in this jet by the way....

Kim Couturier

My Feedback: (120)

Jordan, I left you a message at your office line... Could you give me a call? 231-929-2315 or 231-645-0216

Tip22v

Dmattul,
Thanks for the setup numbers on the Xicoy, I also have the trainer wing and the K140 setup. I had to send my K140 back to Kingtech again (this is the second time I've sent it back for the same problem) because of a fuel leak somewhere in the front cowl so I have not been able to check my CG using the Xicoy yet. I originally checked the CG the old fashion way using a CG stand, and with the batteries installed way up in front of the nose gear it balanced out exactly where PilotRC marked the CG with a full UAT and a 1/4 tank of fuel. With a full tank it was just slightly nose heavy. My jet does not rotate on it's own, I have to give positive up elevator to get it to rotate. I also don't take off with flaps, on asphalt without flaps it still only takes 150 feet to lift off with plenty of airspeed.

dmattmul

Just a quick heads up, be careful where you place your airframe in a cradle for traveling. (I assume most need a cradle) I must of had mine in the middle of the bulkhead in front of the leading edge and broke the balsa covering a little. Not a big deal but I like keeping my planes pristine. The bulkheads before and after the wing are a little weak with limited amount of support stringers. I was hauling it in my trailer and the suspension system is not that great even though its a twin axle trailer.

Tip22v

I finally was able to weight my dolphin with my new Xicoy weight and balance computer. Full of fuel ready to fly my weight is 30.7 lbs, that's with the stock 100 oz tank using 1K Kero.
Regarding balance the CG is right on the mark with a full main tank, this means I'm landing slightly tail heavy with a 1/4 tank of fuel, which does not appear to be a problem because the jet handles the slow approaches very well.
I don't remember who said it but I think I agree that with the trainer wing the actual CG is farther back than what is indicated on the wing.

George

My Feedback: (57)

Sorry to hear, and it is never good when you can't nail down the exact cause.I know I'm a little late here (and I think I know the answer), but did you use the Xicoy balancer for the Dolphin? If you are suspecting a tail heavy condition, there is some evidence on another thread that you could have possibly gotten some erroneous readings. I'm not saying that was the problem, but something to investigate if you haven't determined the root cause.

erwin peters

Hello, isthere a good quality electric retracts set with electric brakes for this Jet??
Regards
Erwin

Tip22v

Does anyone know if there are replacement tires available? If not from PilotRC, FaiBao? Are these tires a standard size?

I've got 21 flights on my Dolphin Jet and the tires are showing wear. Thanks.

MorseAircraftDevelopment

Hey tip, I have some, give me a pm, or email.