Fly Fly 90mm Red Arrows Hawk

Wingnutz · November 22, 2019, 01:44:33 PM

On TEMAC's home page slideshow, there's a great photo of a Fly Fly Red Arrows Hawk (Michael's I think) landing on green grass spotted with dandelions...I've admired the model every time I see the photo...
I thought Fly Fly models were gone but I recently found out most are still available and since the Hawk is reputedly a great flying airframe (the resemblance between the Hawk and Sebart/Freewing's Avanti is striking!), I pulled the order trigger...twelve days later, a huge box from Hong Kong.
For those of you not familiar with the Fly Fly 90mm EDF models, they're old school (in EDF terms) EPS foam ARFs. They're bigger, lighter and "less expensive?" than the current generation of PNP, RTF, BNF 90 mm EDFs.
EPS (beer cooler) foam makes them light but also means they're not as strong as the newer EPO foam EDFs. Compared to EPO, easy to work on...great for modification...not so good at crashing!
Started with THE WINGS!
Started by sanding in a bit of dihedral...
SPARS
The wing halves have all the ribs and spars moulded in foam, with bottom skins to glue on when you're finished messing around inside. The lack of strong spars results in wings which have a reputation for folding under stress...ask Michael about his Fly Fly F-86!...so I cut holes in the foam "ribs" and added two carbon fibre tube spars. I may add a carbon strip "swept" spar behind the leading edge of each wing.
FLAPS
Added these using Robarts pin hinges anchored in hard balsa "anchors" with the pins below the underside of the wing.
RETRACTS
Fly Fly used to supply air retracts but now supply the same servoless electric retracts that HK sells for EDFs. The wheels are a bit smaller than I'd like for grass field operation, but all three are trailing link and that seems to help on rough terrain. Cut larger 1/8" ply plates and sunk them into the rib/spar foam grid to allow the bottom skin to sit properly.
AILERONS
Supplied mounted (very sloppily) with strand tape...re-mounted with pin hinges.
BOTTOM SKINS
Supplied bottom skins on my Fly Fly F-86 started showing stress creases after only a few flights so for the Hawk, followed the advice on RCGroups and re-cut skins out of Dollar Store paper backed foam board.
No glue or paint yet...photos below! Rudder next.

Frank v B · November 22, 2019, 05:37:31 PM

Hey Mr. Nutz,

It's great to see you are active on the Forum again. We sure missed your presence at the field this year. Please drop by soon... like the Christmas Pilots' Meeting.
You must have a full year of insults pent up inside you.

Regards,

Frank

ps: Where is the usual Canadian beer bottle in these pictures. How do we know they are your photos?

Wingnutz · November 22, 2019, 06:07:45 PM

Quote from: Frank v B on November 22, 2019, 05:37:31 PM
Hey Mr. Nutz,

It's great to see you are active on the Forum again. We sure missed your presence at the field this year. Please drop by soon... like the Christmas Pilots' Meeting.
You must have a full year of insults pent up inside you.

Regards,

Frank

ps: Where is the usual Canadian beer bottle in these pictures. How do we know they are your photos?

Hi Frank,
Obviously, I haven't been taking many photos. I'll try to do better and include the ever present beer bottle in the photos!😁
Weather permitting, I'll try to make the Dec Pilots Mtg

Wingnutz · November 27, 2019, 10:56:21 PM

Got back to the bench for a while and cut the rudder out and hogged out the hole for sinking the rudder servo into the v. stab.. Man, those little foam cells end up everywhere...seems they've acquired a static charge and stick to any and everything!
I tried to order a blue one to do it up as a CT155 but had to settle for a Red Arrows colour scheme which with Callie's help will be modified slightly to the 2019 Red Arrows scheme, the livery the Red Arrows used this past summer when they visited North America. The only significant change is the rudder scheme...

Wingnutz · November 30, 2019, 08:45:38 PM

MOTOR MOUNTING
The motor and ESC arrived a couple of days ago and brought its own problems. I chose a Freewing 90mm 12 blade fan/motor from FW's Venom as I really like whooshy sound it makes. The EDF shroud is flared on the intake side and the airways in the Hawk are designed for a non-flared EDF. So, more foam excavating to make the EDF fit. Again, foam cells everywhere!
ESC MOUNTING
Fly Fly provides a cavity for ESC mounting on the outside of the fuse, but it's behind the wing and way too far back for getting the cg right. Did the same as I did on my FF F-86 and cut an ESC mounting hole in the top of the intake airway, ahead of the EDF. I'll cut a "cheater" intake in the outer skin of the fuse and see if I can devise some kind of "cheese grater" intake grill to help achieve the Venom's whooshy sound and allow air to get sucked over the ESC.
MOTOR HATCH
The fuse is designed so that left and right halves are glued together with the EDF already in place. With the limited hatch provided, the flared EDF is not going to come out so the hatch has been widened to allow the motor to be removed if that proves necessary.

Wingnutz · December 02, 2019, 11:04:51 PM

NOSE GEAR
Following the RC Groups build thread, I cut a plywood plate to mount the nose gear retract and slotted the plate into the moulded formers in the fuse. The plate was extended forward to support the steering servo and the retract was re-configured to mount as shown. The rx battery and old rx in the photo are used to test operation of servos and retracts and clearances as I build. I'll use the 10ch rx once it shows up. The fuse is resting on a 3" foam pad which helps prevent hangar rash while building...especially important with soft EPS foam that's already painted!

sihinch · December 03, 2019, 04:41:47 PM

That looks like the same gear I used on my FlyFly Phantom, Bill. If I could do it again, I'd use something with a stronger pin...

Wingnutz · December 03, 2019, 06:01:37 PM

Quote from: sihinch on December 03, 2019, 04:41:47 PM
That looks like the same gear I used on my FlyFly Phantom, Bill. If I could do it again, I'd use something with a stronger pin...

Simon,
That's a beauty! Must have been sleeping if that one has been here on the forum already.
Do you remember if your pin is 4mm or 5mm? The one I'm using is 5mm and it looks pretty sturdy. Thanks for the heads up!

Wingnutz · March 09, 2020, 09:06:59 PM

Back to he Hawk after a lengthy absence. The FW 90mm EDF is too large to allow the fuse halves to seat properly so opened them up using careful cuts with a utility blade knife and finishing the enlarged opening with sandpaper wrapped around a..no, not a beer bottle (too small a diameter) but another Canadian beverage icon...a Tim Horton's coffee cup!(china version) with an o.d. exactly the needed size.
I'm giving the Beriev beer bomber a rest until the Hawk is done.

Wingnutz · March 16, 2020, 01:02:14 AM

The Fly Fly instructions call for the ESC to be mounted in the bottom of the fuse behind the wing. It means long wires from ESC to battery and like other builders of this model, I prefer to mount the ESC between the motor and battery which keeps the wires (10 ga) shorter. Moving the ESC forward involves moving the battery back into space not designed for it. Following the RCGroups thread on this same model by fellow Canadian 4stripes, cut a battery opening through the last two formers ahead of the wing and built two balsa walls to keep airflow to the EDF smooth and create an extended opening for the battery so it ends up far enough back to balance.
The fuselage comes in four sections and the photo shows the two inverted front halves with the balsa in place.

Wingnutz · March 27, 2020, 05:55:53 PM

Social distancing provides some model building time, but still seems difficult to make it to the model bench.
Whining aside, I have epoxied fuselage left front to left rear and same for the right side. Photos show fuselage left and right halves ready for gluing.
As mentioned, I re-located the ESC. Following the two RCGroups builds, I've re-located the ESC between the motor and the battery, shortening the wires. However, unlike the other builders, I put the ESC at the top of the fuse, ahead of the motor and opened a cheater hole in the top of the fuse to allow air to be drawn over the ESC. The ESC itself is set on edge, held to the top of the fuse with two-sided tape.
The ESC location choice moves the CG forward, necessitating moving the battery location back and creating a new space to accomplish this. Balsa walls (previous post) were constructed to allow the battery to be moved back into the intake duct space, the obstructing foam was cut away and the battery tray has been re-located. Electronics used are listed;
Battery- 4500mah 6S
ESC-130A Freewing with 10 A sbec
EDF-90mm, 12 blade Freewing
RX-Lemon 10 ch
Stab - Eagle3A
Next...glue the two fuse halves!

Wingnutz · March 29, 2020, 06:37:10 PM

THE BIG STICK
Pompous title for simply gluing the fuse halves together, but I was apprehensive sticking the Fly Fly F-86 fuse halves together when I built it back in 2013, and no less when sticking the Hawk halves together yesterday...there is(are?) a lot of things that have to line up and you only get as long as it takes for the epoxy to set...I used 30 min rather than 5min.

I'd already checked all the fuse servos and nose retract...good thing as I found one connector I'd assembled backwards.
My fears proved unfounded and everything went together better than I'd hoped! I used an adjustable strap, masking tape with the sticky side out (pretty sure the sticky side would have lifted the paint) and elastic bands to hold the halves together while the epoxy set.
The battery tray wouldn't fit in its new cavity, but the hole in the bottom of the fuse allowed some remedial foam hogging and a secure battery tray mount.
Wing halves next...

sihinch · March 30, 2020, 08:59:10 AM

Looking good Bill. I love the masking tape backwards trick - not heard of that before! It's genius.

Aside from the F-86 in the background (through the window) what else have you got hiding back there?

Wingnutz · March 30, 2020, 07:20:40 PM

Quote from: sihinch on March 30, 2020, 08:59:10 AM
Looking good Bill. I love the masking tape backwards trick - not heard of that before! It's genius.

Aside from the F-86 in the background (through the window) what else have you got hiding back there?

Hi Simon,
The area behind my workbench is a three season sunroom, not heated in winter so it becomes a seasonal hangar for the models I'm working on (all EDFs) and a twelve month hangar for floatplanes.
There's the Fly Fly F-86, an FW Venom, an FW L-39, two Seawinds, an Icon, Beaver on floats, and an eFlite Carbon Z Cub on floats...it's getting crowded!

Wingnutz · April 02, 2020, 07:05:42 AM

WIRING THE WING
A little art, a little science and hopefully a little humour here.
The wing mounting proved a nuisance as Fly Fly had supplied bolts that were too short. Happily I had two bolts with blind nuts to fit as trying to source these in my small village during Corona days would not be fun. Then, the fun of hooking everything to the receiver began!
Art...included this gorgeous shot of the Red Arrows. For added enjoyment, simply note the position of the horizon...
Science(okay calling this science is a stretch) ...second shot shows how I help my seniors brain keep track of all the servo leads. There are ten servo extensions, three stabilizer leads and one satellite receiver plugged into the receiver...it's crowded in there! Before printing labels for the leads I stick a strip of 1" wide masking tape on a waxed paper backing. This keeps the tape flat and the back side clean while I print the label...simply cut off enough for the label and apply it to the correct lead.
Ever had that old Sharpie extra fine you've been nursing for years dry up? Cap it tightly and store with the business end down!
Humour...I'm surprised Frank hasn't called me to task for omitting my trademark Canadian beer bottle in recent post photos. I've found two new trademarks!
It all works and the Hawk went for a short taxi trial across the family room floor yesterday.