Micro F15 twin 35mm EDF

[Joe 1320]

Some time ago, I got into my first twin EDF. There was a certain fascination with a pair of EDFs with their characteristic whine. The only downside was that in order to get any real performance the plane had to carry a significant sized battery due to the fact that a pair of EDFs would draw huge amounts of amps. With the intro of lipo batteries, the physical weight of the battery could be much less, but that still didn't help the fact that a pair of EDFs could still torture a flight battery. As technology in the smaller EDFs has come into play, it sure seems we're in the golden age of electric jets and with that comes another member of the Skyangel Jpower lineup of microjets.



The F-15 was designed in 1967 as an air superiority fighter and since it entered into service, has been sold to several countries and is expected to remain in service past until at least 2025. This new model in the Skyangel line is molded from tough EPO foam and features twin 35mm EDFs with brushless motors. It features a lightweight servo arrangement of only two servos and uses Delta (or Elevon mixing depending on your transmitter) that couples the elevators and ailrons together. This system is very effective on small models that have equally small flight control surfaces. I've had quite a bit of EDF jet experience along with micro airframes so when I saw this model available as an airframe only, I had to make the purchase. F-15s are not quite as overmarketed as some of the other planes, in fact this is the only micro F-15 that I'm aware of unless one wants to convert an old stick and tissue model. That in itself makes the decision easier for those who like flying more than building from scratch. The model is also available as a plug and play for those wanting virtually instant gratification, just add your own receiver and lipo to round out the complete package.





The model arrived from www.hobbyb.com is perfect shape, excellent packing by the vender who is a relatively new company based out of Canada. They appear to be the go to source for the Skyangel / Jpower line of Jets and Warbirds as their selection is much greater than what I've seen elsewhere. Prices looked great and shipping was not out of line, all the better! They even carry spare parts like control horns and rods, EDF fans, clear canopies, motors, etc. for a well rounded offering of products. I had run across several people who successfully ordered from them so I indulged myself and bought several items including the micro A-10 and the new 50mm Screamer.

The parts were laid out and the plan was formulated.





I typically like to mock up the plane first, this model's construction is slightly different. The main fuselage is made just like the other Skyangel jets, including a magnetic EDF cover. The difference here is that the vertical stabs would have to be glued to the fuselage before the horizontal stabs can be glued in place. Since the model's power system and servos need to be installed, it's best to leave off the rear surfaces so that the model can rest on it's back during the majority of it's assembly. Once the powersystem is completely installed, then the final parts are added.





The 2g servos are glued into place and the wires are run in thier pre molded channels to the center of the fuselage. The receiver location was chosen to be in the very rear of the plane for several reasons. The first was to place more weight in the tail in order to balance a heavier lipo if desired. Another reason was to eliminate the need for any servo extensions and to keep the receiver far away from the speed controllers as well as the lipo. 2.4 ghz has been known to have difficulty with being shielded by a lipo so there will be no potential issues here.



　
The EDF units are mocked into place to test fittment and all looks great. This powersystem was removed from the MIG-29, another skyangel jet that had been flown into oblivion and the airframe was getting tired from impacts due to my bravery. EPO can withstand so much more abuse than EPS foam or balsa that you find yourself doing stupid stuff like inverted passes attempting to brush the grass with the vertical stabs, fly in between bushes and other things that one wouldn't do when flying a fragile airframe. The motors and fans are carried over, but I have chosen to upgrade the ESCs to a pair of 10A. The stock escs are rated for 6A and work fine for stock voltages, but I'm not one to normally be satisfied with basic performance levels. After all, the F-15 is supposed to be an air superiority fighter and this one comes with drop tanks and ordinance, I figure it should be assembled with more than just basic power. It will be able to use a 2s lipo if I'm in a lazy flight mood, or rip along on 3s power when called upon.






After the fans were mocked into place, the power system was removed from the airframe and the stock 6A ESCs were seperated, new 10A ESCs that were 3s capable were installed. The during the test, one fan was vibrating and I discovered a hairline fracture on one of the impellers. I swapped both impellers with the three blade versions that are typically supplied as extras when purchasing an ARF. This would be a good test as to how those 3 blade impellers perform. The theory is that the reduced rotating mass would allow for a higher RPM and a reduced amp draw. We shall see.....

After everything tested fine, the fans and ESCs were installed into the airframe and held in place with a little silicone glue. This prevents any unwanted fan movement and takes the burdon of holding the fans away from the hatch cover. The main power lead was fed up to the large battery area and the hatch cover was popped into place. Everything was tested once again just to be sure, now it's time to finish the model.




The horizontal stabs are glued into place with 5 minute epoxy and allowed to dry. Next, the elevators were glued into place and also allowed to dry. They have to be done in this order as the vertical stabs play a major part in the mounting of the elevators. Once those parts are secure, all that is left is to install the control horns and rods. The control rods are attached to the servos and the horns, secured with a set screw and final testing performed.




The kit doesn't come with a pilot figure like the plug and play models but I had one left over from a Mig 29 so I glued him into place and attached the clear canopy with a flexible silicone type glue. That assembly pops into place with a mounting tab and magnet and we're ready to rock and roll! The CG was verified to be 32mm back from the laeding edge wing root so it was time to take a maiden flight test hop.







Flight test

The hand launch was fairly uneventful with just a hint of roll to the left. After just a couple seconds I immediatly pull the stick back and pointed the nose straight up and it climbed straight up without any drama. The first flight's main purpose was to test for any thrust line issues that were quite apparent in the Mig-29. Even though I thought it was a fun model, it has some issues. This F-15 shows none of those traits and flys rock solid. In fact, it's perhaps among the most stable I've flown. There are no pitch issues when going to full throttle nor chopping the power and going dead stick, It actually behaves like a much larger plane that is devoid of any twitchy handling. Rolling verticals, large and even loops, inverted, and nice dead stick glide properties. In fact, I didn't even do any programming in the transmitter. I was expecting a hair more speed, but perhaps after playing with the new 50mm Screamer on 4s I might be a little spoiled. I cannot really complain as it moves along quite nicely. The 3 blade impellers sounded fairly quiet compared to my Mig-29, the thrust was good and the model cannot be described as underpowered in even the slightest degree. Once I swap in a pair of 5 blade impellers I will post a follow up of the flight performance.

The weather conditions have not been the greatest, there are tropical storms headed our way and the conditions show in the video. The lighting was a little challenging as was following the model, but you'll get the idea of how well behaved this model is.

So here is the maiden test hop

F-15 35mm Maiden test

In conclusion, the F-15 came out better than expected. There are no ill handling traits, there is plenty of room in the battery compartment for a wide range of lipos, overall I can see this being a favored model for park flying. The dead stick glide is quite predictable, the power is great on 3s, the sound is good, I can't really find much to complain about.

The Pluses
*Durable EPO construction
*Fairly easy to build
*Excellent flight characteristics
*Large battery compartment
*Excellent space for electronic componants

The Minuses
*No instructions included. It's not critical, but even with an airframe only, the CG should be indicated.
*No pilot figure like what comes with the plug and play models.
*Vertical and horizontal stabs require care when being glued to ensure proper location.
That part is not quite the no brainer like some of the other Jpower models. It's still fairly easy though.
The positives really do outweight the negatives by a wide margin. Consider the negatives a minor gripe.

So if you like the F-15 and can fly larger models, you should have no problems with this one. The flight characteristics really do feel like it's a much larger airplane but you can keep this in the back seat of the car for a lunchtime flight or two in the local park. It's easy to hit your spot on landing, the EPO construction should allow for quite a few tumbles that would turn EPS foam into confetti. is this plane for a beginner? Maybe.... I could see this being a first EDF for someone that has experience on other trainer type aircraft due to the fact that there are no bad handling traits and a dead stick glide with this one is exceptional for a micro.

[Arbo]

Watching this one...

[dahawk]

Boo Rah ! Another one on the list.

[Joe 1320]

the maiden test hop was a success, the original post has been updated. I'm pleasantly surprised, this kicks the Mig's hiney.

[dahawk]

Nice Review Joe ! Good luck on the storm that's on the way ! Been through a few of those when I lived in Fla. Maybe you can find a "Hurricane Hunter" and make RC history

[Joe 1320]

Originally Posted by dahawk

Nice Review Joe ! Good luck on the storm that's on the way ! Been through a few of those when I lived in Fla. Maybe you can find a "Hurricane Hunter" and make RC history

Haha! I went out in the break in the rain from the tropical storm and flew a 24" wing. The wind was pretty stout but the wing handled it just fine. The landing was a bit touchy, but since it came down in one piece it was a success. It took full power to make headway in the wind. Best guess was 35-40mph winds. Yeah..... I'm nuts.

[termite]

Joe,
Could this also be flown in a large gym indoors?

NICE Reveiw Joe
Thanks
Randy

[Joe 1320]

Originally Posted by termite

Joe,
Could this also be flown in a large gym indoors?

NICE Reveiw Joe
Thanks
Randy

Hey Randy!

Indoors huh? Well, I think you would need larger than a regular gym. It could be done, it would be difficult as these cover some ground quickly. I would think soccer field size indoor venue would be ideal. If you fly in a smaller venue, there is no way you'll be able to use the speed unless it's short bursts.

[termite]

Thanks Joe,
We do have a LARGE sports dome available a couple times every winter!!!

Thanks Again
Randy

[Joe 1320]

The more I think about this, I believe you could loaf along in a gym and have some long flight times. The wing loading is low enough that it doesn't take lots of speed to hold altitude. Then in larger venues, let it rip!