Sold the P-47

I sold my P-47 on craigslist today.  I liked it, but for whatever reason, it wasn’t my favorite to fly and I’ve got my eye on something else … but I need to free up some space first … !  I really enjoy flying my PBY though … I need to set up a category and post a few pictures of that soon!

More wing related repairs

I encountered two more issues that I needed to address:

  1. The cheap retract servo stripped out.
  2. The rear wing hold down threads stripped out.

I replaced the retract servo with a much higher quality hi-tech metal gear servo and spent about 10 minutes fiddling with end point adjustments and linkage lengths to try to get non-binding operation and minimize the servo buzz.

The stripped rear wing hold down threads was a bigger problem.  I tried to glue a nut to the back to replace the cheap plastic threaded plate, but just made a mess of things, got glue on the threads, etc.  Just a big mess that was hard to deal with due to it’s location and inaccessibility when things are lined up and put together.  So I went old-school — found a “blind” or “t” nut (like you use when kit building to anchor firewall mounts, wing mounts, etc.) and found a matching non-metric screw (my hardware store doesn’t sell metric t-nuts.)

So that’s it — no pictures, but the repairs are complete and the bird is airworthy again — at least until the next cheap part strips or breaks. 🙂

P-47 Wing Repair

The Hobby-Lobby “Hun Hunter” P-47 seems to have a small design flaw.  Because of the size of the wheel well required for retracting the gear, there is not a lot of foam material along the leading edge of the wing in this area.  At the thinest point, it’s pretty thin. The wing is subject to cracking in this area — starting at the leading edge and proceeding through the middle of the wheel well.  There is a carbon spar in the wing so the wing isn’t in any danger (I don’t think) of coming off in flight, but it does create greater flexing and makes me nervous.

It seems that any landing that is less than perfect has potential to crack the wings.  I can grease in a sweet landing now and then, but once in a while everyone bangs in a little harder than they intended.

In an attempt to repair this problem “permanently” I cut two small pieces of glass cloth, about 5/8″ wide by 1 – 1/2″ long.  I then used a mixture of slightly thinned 12 minute epoxy to glass in this cloth.  The picture below shows the outline of the tape along with the rough location of the crack (in green.)

The tape blends in pretty well once the epoxy saturates it, although the epoxy will cure a bit yellowish.  This takes away from the perfect scale appearance of the aircraft I’m sure, but what are you going to do?  I want to be absolutely rock solid safe in flight.

Launching Update

Update on MiG-15 Launching Technique

Here is a launch tip for anyone who’s struggled to get the Hobby Lobby MiG-15 airborne reliably:

First, recognize that at FULL throttle, there is a small tendency to want to pitch up (probably due to the large mid-T tail configuration more than thrust lines.

Second, recognize that this is not a prop plane so there is no prop wash flowing over the control surfaces. All control surface effectiveness is due purely to forward speed. During a hand launch, forward speed is at it’s slowest and control surface effectiveness is at it’s lowest.

The problem: At full throttle and very slow speeds, the tendency to nose up is stronger than the control surface effectiveness, so right after the aircraft is thrown, even with full down elevator you may not be able to overcome the nose up force of the motor. This leads to the aircraft floundering … the full thrust is pushing the nose up, keeping a high angle of attack, and forcing slow flight speeds. The control surfaces can’t compensate due to slow flight speeds and no prop wash to help out. You can’t push the nose down, you never begin to accelerate, and often the flight ends after a few seconds as the aircraft stalls/flops/cartwheels in.

The solution: Launch at 2/3 to 3/4 throttle. (Basically keep the throttle as slow as you dare on launch.) Throw the aircraft level or even on a slightly nose down trajectory. This reduces the tendency to nose up, allows gravity to help accelerate the aircraft a bit, and allows the aircraft to accelerate naturally, and fly off as expected.

The launch problems with the MiG-15 are EXTREMELY frustrating, but once you get your launches dialed in, this little bird is a blast and really performs well! One final tip: this MiG does have a nasty spin if you manage to stall it. I try to hold at least 1/3 to 1/2 throttle through my turns and I’m careful not to pull too hard on the elevator. Let the plane fly itself, keep your control inputs light and you should have no trouble staying above stall/snap speed.

Hobby Lobby P-47

Introduction

Hobby Lobby recently introduced a neat P-47 warbird model.  It has a 40″ wing span, 4-channel flight control, retractable landing gear, and comes receiver ready.  It includes servos, motor, speed control, and even a suitable battery.  All you have to do is some basic assembly, install your receiver, and you are pretty much ready to go.

Construction

Here are the tail surfaces as they come out of the box.  Everything is pre-hinged.

Here is the fuselage as it comes.  The motor and speed controller are already installed.  Servos and linkages are installed.  Even the cowl comes pre-installed:

Here is the wing.  As you can see, the two halves are already attached.  The landing gear and retract system is already installed.  The servos and linkages are also installed and the control surfaces are hinged and attached.  The wing flaps are not operable by default, but I noticed there are servo mounts molded into the wing and it would be a 30 second job to cut the wing flaps loose and hinge them.  So if anyone really wanted to add flaps for additional realism, it should be a straightforward mod.  The aircraft definitely doesn’t need them though … it slows way up if you want it to and flies very stably at slow speeds.

Here is a close up of the machine guns on one side.  There are tons of little details built into this aircraft!

The prop was a neat surprise.  It’s an operational, scale, 4 bladed prop.  The prop tips are painted yellow and it really looks neat when it is stopped and when it is spinning.  It includes a scale prop hub and the final result looks really sharp!  I’m sure the prop is not the most efficent choice, but it looks great, and works great so I’ll run with it.

After hardly any effort or time, I ran out of things to do and the aircraft was done.  It’s midnight though so I took it out in my driveway for a pre-maiden photo shoot.  She really looks sweet.

Here is a good view of the business end.  You can see the scale prop and the retract system.  Very nice!

… time passes …

The next day after I finished the airplane we got a giant snow storm here in Minnesota.  Blast!  I figured it was still late fall, wait a few days and this first snow fall of the season would melt.  But unfortunately, mother nature had other plans for us.  The temperatures dropped, more snow came, and more, and more.  The RC club field was buried for the winter. 🙁

Fast forward to April.  The snow has finally mostly melted and the road to the field has dried out enough to be passable with normal street vehicles.

The Maiden Flight

I snuck out to the flying field for an early lunch break.  The winds were relatively light @ 5-10 mph.  But they were at a 45 degree cross wind though which was the only minor complication.

Here are some pictures before the first flight.  I also have a battle tested Hobby Lobby MiG-15 that uses pretty much the same battery so I brought it out as my “backup” airplane in case I found a problem with the P-47 and couldn’t fly it.  I hate wasted trips to the flying field!

She’s just as pretty in the grass in the morning as in my driveway at midnight. 🙂

Maidening a new airplane can get the butterflies going, so I always try to tell myself that these things are designed to fly.  They want to fly!  It will fly great!  And that’s the truth.  I had to dial in several clicks of right aileron and a couple clicks of up elevator and I was grooving around the sky.  The scale prop doesn’t offer blazing top end speed, but it’s solid and gives good power.  There is plenty of HP to climb very agressively.

Retracts!

I’m especially excited about this P-47 because it is my very first RC model airplane with retractable landing gear.  A WW-II warbird really needs retractable gear.  It just doesn’t look right flying around with the gear down, and if you build it with no gear at all, then you have to hand launch and belly it it.  The retracts worked great with two lessons learned:

  • I mentioned earlier I had quite a significant cross wind.  On my very first landing I mismanaged my rudder and my slip and touched down with quite a bit of side load.  This collapse the upwind gear leg and I skidded to a stop.  Dohhh!!!  That left a couple scratches on the bottom of the aircraft, but didn’t seem to damage the gear (it just popped right back out when I picked up the airplane) and the big scale prop was safe too.
  • On the second hop, the retracts suddenly stopped working.  Fortunately they were stuck down.  I landed, this time being much more careful with my cross wind technique and inspected the gear.  In my lap, the retracts worked perfectly.  I took off and still couldn’t get them to retract in the air.  Then I took a quick cheat peek at my hands and realized I was trying to toggle the wrong switch.  Dohh!!!  That’s what I get for buying a 7 channel transmitter with about 20 levers and knobs and switches on it.  Once I found the right switch the gear worked perfectly again. 🙂

Nose Overs

I read online that this design has a tendency to nose over and guys were busting up their scale props (and then complaining because they were out of stock.)  So in my test flights I was very careful to hold up elevator at the start of the take off run and touch down with a heavy dose of elevator dialed in.  By the way, this P-47 has awesome slow flight characteristics.  If you are careful to bleed off your speed and flair at the right time, this thing totally slows down to a walk and drops in for a nice 3-point landing.  I need more practice, but on a nice light wind day, I think there’s potential for some really really sweet landings.

Wing Crack

After my first battery was expired, I picked up the aircraft to walk back to the pits.  I noticed a crack developing in the wing foam on the bottom side of the wing, close to the wing root between the leading edge and the wheel well on the right side.  The spar was solid, but there was more flex there than I liked to see.  Bummer, done after one battery, but still happy with how things went.  I’ll file this under “shaking out the bugs”.  Hopefully a little glue will secure the foam and I won’t have any more problems.  It’s something to watch though. Update: the crack was a little more extensive than I first thought … it appears to be from landing, but I don’t recall banging it in real hard. Oh well, I glued it together and hopefully it will hold.

Hobby-Lobby MiG-15 Electric Ducted Fan Jet

Assembly

My birthday present to myself this year was a MiG-15 electric ducted fan model from hobby-lobby.com.  I bought this at Toledo in April (well paid for it in April … it’s a new item so wasn’t yet in stock.)  It shipped in May and arrived on Tuesday.

http://www.hobby-lobby.com/mig_15_epo_jet_arf_rc_airplanes_528669_prd1.htm

Here is a picture as it looks when you first open the box.  I don’t see too many pieces to glue together.

First thing to put together is the tail.  Here are the pieces dry fitted.  The only challenge to assembling the tail is that you are required to free hand drill a hole to slide in a carbon fiber tube that extends into the right elevator, and then drill the matching hole (again free hand) into the left elevator, and do it in such a way that everything lines up.  2 things in my favor: it’s foam so there is some give, and you don’t have to drill very deep (about in inch and a half in each direction.)

The next picture shows the elevator pushrod access panel.

There is a lot of nice detail molded into the undersides of the tail.  One thing I noticed is that the trailing edges of the control surfaces are squared off with hard edges.  This might seem a little unintuitive at first (often control surface edges are rounded in model airplanes) but according to RC University, square edges help minimize flutter problems.

Here is a picture of the fuselage.  It comes with the electric ducted fan and motor already installed as well as the speed controller and the elevator servo.

Access to the electronics is through a hatch where the entire canopy pops off.  There is a tab in the rear and two magnets at the front.  The two magnets keep pulling out of the foam on the fuselage side and I keep regluing them.  I assume at some point I will build up enough glue area so they will just stay put.

Looking down the pipe, you might be able to see the ducted fan blades.  This thing puts out a lot of thrust, enough for nearly unlimited vertical performance.  It really flies like a high performance jet in the air!

The next step is to install the wings.  These plug in and are glued with epoxy.  Notice the dual wing fences on the top of each wing?  A very nice detail!

Each wing/aileron has it’s own servo so as you glue the wing, you need to thread the servo wire into the fuselage center section.  Not hard, but a little care must be taken so you don’t slop epoxy on the wire or connector and create a problem for yourself later.  Again the bottom of the wings has a lot of neat molded in details like the bottom of the elevators.  The elevator and ailerons use real hinges that look very cool.

The next step is to glue the tail assembly onto the fuselage and route the pushrod housings.  The high tail mount means a little engineering needed to go into the kit so that servo inside the electronics bay of the fuselage is able to drive those dual elevator surfaces.  The kit is engineered so this works out really well.

Finally, the last step is to glue on the drop tanks.  For this kit they do not drop.  The tanks are foam and the bottom half is protected with a plastic shield.  If you look closly the bottom of the fuselage nose also has a plastic shield, and there is a raised shield/bump at the tail.  This aircraft has no landing gear so you need to belly it into the grass for landings … thus the plastic protection of the foam is a critical feature.  Also you can see the cockpit hatch piece detached in this photo.

So it’s all done!  The control horns are installed, the linkages are connected, the battery is velcro’d in, the balance point is checked.  She’s all ready to go!

And a slightly lower angle shot … she looks good!

Launching

Here is a video that shows the proper way to launch the MiG-15 (important because a bad launch can result in a mishap.)

MiG-15 Launch Technique

Flying

This MiG-15 is definitely not a beginner’s airplane.  Fortunately I am not a total beginner.  Unfortunately I’m not an expert in hand launched foam ducted fan electric jets either!  Be careful on the hand launch and release it straight and hard (or wait until there is a day with a little wind.)  The ducted fan doesn’t blow air over the flying surfaces so until you accelerate to flying speed you are vulnerable.  I flopped it in once and broke off a wing (now fixed.)  Other than that, It’s not hard to fly once you are up and flying, and anyone with reasonably competent RC flying skills should be able to get the hang of it very quickly.

As I mentioned, because the MiG-15 has no landing gear so it must be hand launched.  For my first two flights I asked a buddy at my RC club field to throw it for me.  I ran up to full throttle, he threw it into the air, and off she went!  For my 3rd flight I attempted to hand launch for myself and that didn’t go so well.  It might be worth using an assistant for all launches or just make sure you throw it a bit harder than you think you should and make sure you release it very straight.

Unfortunately I didn’t have my camera out for the first flights, so I don’t have any flying pictures yet … hopefully next time I head out I can get some action shots.

Wow!  It’s a a total blast to fly!  It has nearly unlimited vertical performance and can do some really sweet low/fast passes at full throttle.  It really looks and feels like a high performance jet in the air.  For its size it feels like it flies at very scale speeds … in other words it’s fast and impressive and goes from a tiny dot at one end of the field to a tiny dot at the other end of the field really quickly.  And if you pull up vertically you can get as high as you need to go also very fast.  But it’s all foam and pretty light, so you can also cut the throttle and cruise by for a slow pass at just a couple notches of power.

One thing I found I needed to be careful of is that she really bleeds off speed in the turns, so even though you can do a nice slow level pass at just above idle, you better be careful to power up to 1/2 throttle through the turns or they will get really exciting on you.  (Imagine a lead leaf if you get too slow in the turns.) 🙂

It’s pretty hot on landings too, but once you get down into ground effect you can start bleeding off a lot of speed and touch down pretty gently.  The drop tanks act as landing skids, but I worry about one of them ripping off if I would come in too hot or drag a wing in a cross wind and catch one of them on something.  So I was very careful to keep the wings level and bleed off as much speed as possible before finally touching down, and everything worked out really well.

My only gripe is that the battery runs out too quickly … I’m not done having fun before it’s time to bring her in for a landing.

Retired

Sold on November 30, 2012 — hopefully with many great flights yet to come for the new owner.

Great Planes Big Stick 40

 

Great Planes Big Stick 40


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This is an original release (not the updated version, nor the up-updated version.) I got a great deal on it and I missed my old Sweet Stik so much I had to build another Stik.

December 4, 2012

I have sold this aircraft.  I hadn’t flown it for a couple seasons and my focus has been more on electrics lately anyway.  Hopefully the new owner has many good flights!

June 2, 2008

Successful maiden flight!

 


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IMG_1120 There’s not too much to say … she flies a lot like a stik. 🙂 Today was pretty windy and lots of swirling eddies at our field. I played with control throws and dual rates on the ailerons. The initial rates were pretty lively for a landing approach, especially in the crazy winds we were having. I had one dead stick … pulled the idle too low on approach, but was able to land and roll out entirely within our runway. The GP 42 offers plenty of power for near vertical performance. The tail dragger configuration is kind of tricky on the ground though … I might substitute larger wheels?

 

June 1, 2008

I got fed up with this thing sitting around unfinished, and I was really itching to fly it, so I spent the last day and a half this weekend knocking it out. There are a few things that maybe aren’t perfect, but this is a old school ARF so things don’t line up as well as newer ARFs. So I think it will be good enough, and fly well enough. It’s pretty much ready to go.

I’m excited about this airplane because my first post-trainer aircraft was a Midwest Sweet Stik and it flew great and I loved it. But my original (built in 1984) was getting rattier and rattier so I eventually sold it to some guy for cheap … probably ended up as target practice are trash can filler somewhere. So this project lets me revisit one of my all time favorite models, but with a snappier engine, hopefully lighter airframe, and this time as a tail dragger configuration.

 

November 19, 2005

Today I reinforced the floor at the rear of the cabin in case I want to install floats later on. I then installed the main servo mounting tray. Finally I cut and began installing the pushrod housings.

November 14, 2005

This evening I went to the hardware store and purchased 4 sheet metal screws small enough to fit through my engine’s mounting holes. I positioned the engine and using my new “dead center” tool, marked 4 engine mounting holes “dead center”. I drilled them out and sure enough they were dead center. Finally I used my replacement screws to fasten the engine to the mount. Simple basic stuff. 🙂 I really need to get a flight pack because servo/linkage installation is the next step.

 


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November 10, 2005

Two days ago I dug out my epoxy and glued the 3 plywood wing joiner pieces together to form one hopefully strong enough wing joiner/spar piece. I’m always nervous about wings folding up in flight, but I’ve never had one fail in flight [yet]. 🙂

 


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Yesterday and today I diddled away at a few more things and pretty much finished up the wing minus the servo and linkage. I’m still negotiating with the wife over how we are going to fit a new flight pack into the family budget. 🙂

I started looking into the engine mounting today. The supplied engine mounting screws are too big for the holes in my engine. I have a really nice running Thunder Tiger GP42 I am putting on this airplane. I guess I’ll take a trip to the hardware store tomorrow.

 

Piper Cub Photo Shoot (Floats)

Photo shoot from my maiden flight off floats.

I finally got organized enough to get my Cub up to my parent’s lake. There is a small thin sheet of ice forming at the middle of the lake so this is most likely my last chance to fly off water this year.

Comments

3 things I need to address: 1. One of the servos is draining the battery *way* too fast. My voltwatch is warning of low voltage long before I burn through the first tank. 2. It is somewhat tail heavy … flyable, but you have to be 100% hands on. 3. The floats are mounted so the aircraft sits a bit too tail high in the water. This probably helps getting airborne, but it looks somewhat unnatural.

Despite a few issues, she performed beautifully. She tracks really well in the water. Take off runs are straight and true. It’s easy to get up on step then backoff to a few notches of throttle, center the elevator, and skim along the surface. Then just add some throttle and she’ll accelerate and take off. She’ll get airborne on 1/2 throttle.

I was concerned about flying weight with the extra load of the floats. But it was absolutely not a problem. Flying speed was still cub-like and only a few notches of throttle was required to hold altitude. The main problem was being slightly tail heavy. That meant I had to be on the controls, keep pushing the nose down, and keep correcting when it would start to break one way or the other if it did get too slow. I never felt like I was in danger of a stall, but never was able to really relax and let the plane fly itself either.

Sig Four Star 40

Sig Four Star 40

Kit built, purchased Spring, 2005. Sold to a fellow club member (I forget the date, but maybe Summer of 2006-ish?)  Yes, it is pink!  That is what I get for buying off of ebay. 🙂


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November 11, 2005

Today we had unseasonably warm weather (high of 61F!) so I shifted around my work schedule so i could fly in the afternoon. I replaced my aging/ailing transmitter battery and needed to test the new one.

The 4* is a lot of fun to fly … quick, nimble, easy inverted flight, tracks really well through loops, does outside loops with ease, does nice rolls. It makes the pilot look a lot better than he really is. 🙂

For the first time in my life, I took off, climbed a bit, rolled inverted before the first turn and flew for a while inverted. Usually I wait until I’m really up high to try that scary stuff, but the 4* does such a good job it softly beckons to me … “come on, fly inverted, do it lower, how about a roll 20 feet off the deck, you can probably do it …”