Buzzard Bombshell Electric Conversion and Mods

About a year and a half ago I picked up this wonderful high wing balsa old timer at a swap meet.  I did not know what it was but I'm a sucker for an inexpensive balsa old timer, especially a three channel high wing.  He wanted $25.  I offered $15.  He threw in a motor, esc, and two servos and we settled for the $25 he was asking!  I was a happy camper.

After some time and a bunch of Internet searching, I finally discovered that what I had bought was a plane called the Buzzard Bombshell.  The original design was done and built by Joe Konefes in 1940  with about a 72 inch wing span.  It was intended as a free flight as RC gear was way too expensive for most people.  This plane was designed to head up as high as so many ounces of fuel would take it and then glide for as long as possible (Joe flew his for over 49 minutes at the 1940 NATS).  To help with extended glide times they incorporated large tail surfaces that helped with lift and moved the CG to 50% or more back from the leading edge.  With the heavy motors of the time, this made for an interesting stubby nose look.

Mine was a more current and smaller version that was intended for 1/2A power sources.  It looks like it was setup for a Cox .049 judging from the mounting holes in the firewall.  Now by smaller I mean about a 45 inch wing span and still a good size plane.

Didn't realize that these cluttered photos were the only ones that I had at the time I posted this.

I'll take some better ones as soon as I get some time.

A couple of things that I really liked about this plane is that the builder did a pretty good job of construction and covering, but also, I see no oil residue and so don't think that a motor was run on this plane let alone even mounted.  I don't think it has ever been flown.

The first thing I looked at doing was to figure a motor mount

You can see here the holes for the original motor mount.  Fortunately the builder install blind nuts from the back side.  I just needed to figure out what size they are and how to go about using them.  They are oddly laid out so I can't directly use them and I'll need an adapter.

You can see the blind nuts in this photo.

I decided to use a circle of 1/8 inch plywood.  I would drill holes to line up with the engine mount holes and then drill holes to fit the electric motor mount.

I lined up the disk from the back side so that I could transfer the mounting holes from the front side.

Here is what I came up with.  I started counter sinking the holes so that I could use flat head screws so that it will fit flush against the firewall.

Here are the parts that I came up with to create my motor mount.  I ordered some aluminum stand offs from an online source and screws and washers from my local hardware store.  As I recall all of the threads turned out to be a standard 10-24.

Here is how the stand offs will fit with the electric motor x mount and the original motor mount.

This is how it would look with the longer stand offs.

Here is the new round plywood mount test fitted in place.

I needed to ream out the x mount slightly to fit the new screws.

Now the screws fit fine.

Here are the different stand offs and screws that I used.

Here is how it would look with the long stand offs.

This is how it would look with the short stand offs.  I like this look better, it puts the propeller closer to where it would have been with the originally designed gas motor.

I used different amounts of washers behind the x mount arms to set down and left thrust angles.

Here is the end result.

Now I need to start looking at where and how to mount the battery, ESC, and the two servos before I can get this thing back in the air.  These will be done in future updates.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

$5 Durifly Ryan STA(M)

Ok, maybe it will not turn out to be $5, but it started that way.  I was browsing Hobby Kings bargain bin items and under the $0.99 bin I found all of the critical parts for the Durifly Ryan STA(M)!  I was really bummed to find out that the engine cowling and parts kits, while not $0.99, were out of stock, but I can live without those.  I'm not so much looking for a complete, complete deal here, I just want something that I can have fun flying, looks reasonably good, and relatively cheep.

So, here is what I ordered.  One set (yes, set, right and left) of wings, one fuselage, one cockpit, one rudder, and one stabilizer.  Each was only $0.99!  So, ok, this will not come out to a $5 build as I did have to pay shipping and HK is smart enough not to let you order too many $0.99 pieces without ordering something else (I had to split this into two orders!), so shipping cost me about $28, or about $14 each order.  But still, I'm only about $35 into a $150 plane, so far.

I did already add two 9g servos to the wings (about $4 each).  You can see them installed into the wings in these photos.

The really good stuff (besides the parts being CHEAP!) is that everything was already covered, all movable surfaces were already hinged with control horns and stoppers, and the rudder has the tail wheel installed.  All very nice indeed!

The not so good stuff, the wings came without the spare (that seemed really odd!).  So I had to make one using a lot of educated guessing (but I got it done).  The rudder was a little kinked about mid way, right where the balsa color changes.  I have no engine cowl.  I have no landing gear, wheels, or pants (I'll make a set but don't plan on making the pants), the cockpit section came without the dash decals, the manual (as sparse as it was) is no longer available (luckily someone posted photos of theirs on RCGroups), and the hardware kit is no longer available (this included all of the linkage, screws, support wires/string, wing mounting screws, and misc. hardware).  I will also have to provide two more servos for the tail surfaces, a 25Amp ESC, a 3530 1100Kv motor, and a 10x6 prop.

So far I have the wing spar made, the wing halves epoxied together, and the aileron servos installed.

This photo shows the wing spar that I cut from 1/8 inch plywood.  I measured the depth of the slot in each wing to come up with an estimate for it's length.  I measured the angle of the wing roots to come up with an approximate dihedral angle.  I carved and sanded until it fit and the two wing roots came together nice and flush.

I then put a liberal amount of 5 min. epoxy into each wing root spar opening and covered the root faces with a thing layer of epoxy.  Then I slid the left side of the spar (yes, it has sides to match the wing) into the left wing and then slid on the right wing onto the right side.  Then I taped up the bottom side good and flush (lower photo) and then pulled the top side together nice and flush and secured with tape (upper photo).  I left this to sit over night.

Here is what the parts look like so far.

Check back again and find out how this new project is coming together and as usual, thanks for stopping by my blog.

Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Wing One Rebuild (Say that fast 5 times)

This beauty was my next project!

This wing came to me from the second owner who had not actually done anything with it.  He reported that the original owner had flown it with some sort of pod on top that housed the battery, electronics, and motor.  The pod and what was contained were no longer with this wing.  It did show signs of having been flown but was still in really good shape.

Here I started to take the covering film off of the trailing edge of the section between the elevons.  I started to do this because I knew I would need to take this section out to be able to move the motor forward.  I wanted to move the motor forward because I also knew it was going to be hard enough to get the CG right without the motor being so far back.

Here is a closer look after I had cut the trailing edge balsa lose.  I also have the motor/prop combination that I intend to use and the start of a motor mount/firewall.

Here I'm getting an idea of how things will line up.

Here is how I originally thought everything might lay out.

To provide for some flexibility in the power system (in anticipation of crashing), I decided to use a block of stiff foam to mount the firewall.  I cut out the covering film where this foam block will be glued down.

I decided to use Gorilla glue to secure this block as it would expand into the foam as well as adhere to the wood and foam of the wing.  Also, Gorilla glue is more flexible than epoxy (remember the anticipated crashing?).  I used the popsicle stick to help spread out the glue.  I did not show these steps, but I also spritzed it with water to help activate the glue and then held everything in place with masking tape.
(Our cat Dewy is trying to get in on the action)

Here is all of the pieces glued in place.  I made sure to have the motor wires run over the top just because I though it would make it easier to connect up.  Also, you can see the slight up tilt in the motor.  This was done to keep the thrust line pointing to the center of mass.  If you do not do this with a pusher, you will get pitching up or down when applying power.

After doing some CG work (I used an online CG calculator for flying wings to come up where the CG should be for this wing.  I think I used one of these: wingcgcalc and fwcg), I realized that the battery would need to mount like this to get the CG right.  I centered the battery and then traced around it and dug out the foam about half an inch down.  I did not want to go too far into the foam so as to maintain as much strength as possible while still providing a good battery mount.  You can see that I glued some bamboo skewers into the long corners of this cutout.  I also wrapped a strip of velcro around each of these.  I thought that these would help reinforce the foam and help to secure the battery.  This actually worked very well.

Here is a closer look.

 Here the battery is strapped in.

Here I am out for the maiden flight.  A friend who is a really good wing pilot got it up in the air for me and then handed the controls over after he trimmed it out.  Thanks Richie!

If flew great and he was easily able to launch it and trim it out.  I came down a bit hard on a landing and loosened the glue on the firewall.  I just used a couple of rubber band from front to back to secure it and that is what you can see here.  I did this because I was not ready to go home and really wanted to continue flying!

(Editorial Note: I am not condoning the flying of damaged airplanes in any way!)

  It flew great just like this for two flights.  Then I came in rough again and encountered the damaged prop and completely broken loose firewall that you can see here.

Here it is again all rebuilt and ready for another day of flying.

I have been really impressed with how durable wings can be.  I have continued to fly this wing just as it is for many flights including some nasty crashes.  My worst crash was at a pretty good speed into a street curb.  The crash destroyed the battery and broke the hinges on one elevon and the related clevis.  I have since replaced the battery repaired these and flown it again.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Trojan T28 Repair, Again

Well, the last time I took out my wonderful Airfield/FMS Trojan T-28, I was experimenting with the flaps and coming in for slow passes.  I was having a log of fun with this.  Until I came in low and hit that point where it tip stalled and did the left roll thing down into the ground.  Everything after that was pretty much a blur.  The air frame survived without much more than scratches, but a lot of little things suffered.  Needless to say I now have a bunch of repairs to do.

So now here is my list of my needed repairs:
The nose gear strut has a nasty compound bend.

  It's not real clear from this photo but the bend is mostly back and also to the side.

The nose gear door broke the horn.

I've tried gluing this part several times and with different glues and have yet to find a good solution.  I've tried super glue, epoxy, and model glue.  Nothing holds very well and eventually breaks loose.

The right wing gear came loose.

It was only loose, but I decided to take it out completely to make sure it gets secured in good.

The left wing flap servo is jammed.

This is a view of the servo after being removed.

This video shows how the servo is sort of functioning, but you can hear is clicking as the gears skip.  Sorry for the blurry image.  If it was clear you could see the current and voltage readings on the meters.

The motor mount/firewall is loose.

You can see from this video that something is loose and in multiple directions.

There are also several misc repairs such as a loose cowl exhaust flap.

The flap here isn't broken, but it is loose and a little floppy.

Well now you know what I'll be doing for the next few (or many) blog post.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Fun With My SAP Buds at Bilby

Now, before you get a little upset that I may be being rude about my friends, let me make it clear that I mean my Sacrament Area Parkflyer buds.  You can check us out and get some more information about where we commune and fly at this site parkflysac.com.

I went out to my favorite flying area to have some RC flying fun (I like the Bilby site because it's the closest to me) and hit a snag.  I was in such a hurry to get out there that I forgot the wing spar for the one airplane I brought!  Since I could not fly, I decided to video those that were out there and record the fun and commerrodery.  The video isn't great because all I had with me was my cell phone, but I think you will enjoy them anyway.

In this video a nice 4 stroke 3D plane has problems with stalling before take off as a nice foam jet comes in for a landing.  While waiting for the 3D plane to take off, Dr Bob gets ready and tosses up an insanely speedy little wing of his and puts it through its paces.

In this video the 3D 4 stroke comes in for a nice landing while Richie is getting ready to take off his big wing with landing gear.  It's a big heavy wing so he gives himself a lot of run way.  Those of us parked at then end are grateful for the courtesy.  Surprisingly it takes off quickly. It wobbles around quite a bit but Richie soon takes control and flies it quite nicely.  Then someone gets ready to maiden their Apprentice but is troubled with steering issues.

In this video, a really cool foam jet takes of.  This is the same foam jet that landed in a previous video.  No, this video is not out of order, this is another flight.  It took some distance to take off and from my angle, it almost looked like it was going to end up in the back of my Jeep.

This next video starts with a really nice flyby from the foam jet that took off in the last video.  Just after if flew by, Richie landed his big wing with landing gear.  Unfortunately he came down a little heavy and collapsed the nose wheel.  We take a closer look while the foam jet makes some sweet flybys.  After a few more low and casual passes he comes in for a nice landing.

Dr Bob takes out another screamer.  Too bad about 3/4 of the way through while going vertical, the motor screws come loose and the prop catches the right side of the prop slot.  You can hear this in the video.  The result is that the torque causes the motor to spin and rip all of the motor wires out!  Despite this, Dr Bob deftly brings in this wing with a nice glide and drops it right at his feet.




Quite often we have someone maiddening their new plane.  That is the case with this beautiful new WW2 biplane.  Unlike the Apprentice earlier, this one actually gets a chance and flight.  Let's see what happens.

Yeah, OK, I don't know what happened, but needles to say, it didn't last too long.  He'll get a lot of help and make another attempt soon.

We have a lot of fun out here and also at the other sites around the Sacramento area.  Come out and join us, the more the merrier.  There are no fees or dues, we just ask that everyone fly and behave respectfully and also take care of the areas we fly at.

Hope to see you out there!

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Testing to the rescue

Some times stuff happens and you don't really know why.  This is why you need test equipment.

This was the case with my Dad's new 3D plane.  This was a kit that came without any electronics but had recommendations.  Since it was from Hobby King, of course the recommendations were for their parts.  No big deal, I actually like most of their parts.  I helped my Dad figure out what he needed and what was the best fit of parts from the US warehouse.  When he got everything together he noticed that things were getting hot.  Not a good sign.

He had a good idea of how to put a heat sink on his speed controller, since this is what was getting hot, and I helped him figure out the best way to put it on.  What he did was to use some heat sink compound in the center and then some epoxy on the corners to secure it down.  This was of course after cutting away some of the heat shrink to expose the ESC aluminum heat sink.  This is what he ended up with.

Darn good job, don't you think?

This is the other side showing that it is a Hobby King brand 25A (30A burst) variety.  This should already be a pretty good ESC and with the added heat sink, even better.  The velcro in the photo was something he added to help keep the ESC tacked down in his plane (nice idea).

After some testing, it was still getting really hot, too hot to touch and would actually go into shutdown mode!  This already happened once while he was test flying it.  We initially thought he had lost control when it went behind an obstruction, but we no longer think this was the case.

So, now to the testing and test equipment.  I was able to come down with the family and my gear (yes, family comes first. Since there was still some space left in the trunk I could take my gear along!).  We hooked up my power meter in between the battery and the ESC and began testing it out.

We found that at full throttle it was only pulling 14A.  This is well below the rating of 25A, but it was roasting hot after only about 30 seconds.  It even when into shutdown mode about 20 seconds later.  Even with the added heat sink, it was too hot to touch!

We then tested the power draw on my Wild Hawk which I upgraded to a brushless motor with a Turnigy 25A ESC.  This combination drew slightly more current at about 16A, but stayed quite cool and was barely warm after a minute or so of wide open throttle. 

So, this resolved why he lost control.  This also suggests that two other possibilities.  One is that the Hobby King brand parts (or ESC in this case) are not very good, or the other possibility is that they had a batch of much lower rated ESCs go out with the wrong labels on.  We would not have known this without the tester as we would not have been able see that the current draw was well below the rating.

Well, what does he do now?  He has two options.  One is to pursue a replacement from Hobby King and the other is to just go out and buy a more reliable brand.  Since the Hobby King ESC was only about $7, I think he will just look for a better replacement.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Battery of Confusion

I hear a lot of people making comments about batteries that tells me they are confused over how batteries fit into their electric airplane power system.  I decided to do this blog entry to try to clear up some of this confusion without adding any more to the subject.

I hope to clear things up by relating an electrical system to an internal combustion system.

In a simplified internal combustion system the gas tank stores energy (in the form of gasoline), a carburetor controls the flow of energy to the motor, and the motor converts the energy into mechanical motion.

In our electric airplane power systems, the battery stores the energy (electricity), a speed controller feeds that energy to the electric motor, and the motor converts the energy into mechanical motion.

The battery as two parameters that it is rated by, the voltage and milliamp hours.  The milliamp hours is a rating of its capacity, just like a gas tank capacity might be rated in gallons.  A higher number of gallons does not make a car go any faster, it only allows the car to run longer.  The same is true for batteries.  A larger milliamp hour rating will not make your plane fly any faster, only run longer.  There is another little mix to this in that the milliamp rating (multiplied with the "C" rating) is related to the flow rate.  This is similar to a gas tank with either a low or high capacity fuel pump and line.  If an internal combustion engine requires more fuel than than the fuel pump and line can supply, its power and performance will suffer.  So too, if an electric motor demands more current (milliamps) than the battery can supply, the battery voltage will drop along with the electric motor power and performance.

The voltage rating is a little different and is more closely related to the octane rating of gas.  If I have a high performance car motor and run regular gas in it, I can only expect so much performance.  The fuel mixture is only capable of creating an explosion of so much to push the pistons down.  Now if I put high octane racing fuel in the tank, I can expect much more performance.  This fuel mixture is capable of a much greater explosion to push the pistons down.  A low voltage battery can only give its rated voltage to the electro-magnets that repel the permanent magnets.  A higher voltage rated battery will allow for a larger repelling force.

Now, keep in mind, just as the internal combustion race motor is built to take greater stresses, if a batteries voltage is increased, the speed controller and electric motor must be built to take on the extra stress.

I hope this analogy will help those out there that have been confused about batteries and their voltage and milliamp ratings.

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.

Trojan T28 Canopy Repair

Initial damage

 There is one final issue that I have not resolved yet in the reconstruction of my Airfield Trojan T28, and that is the canopy damage.  When my plane crashed, the canopy was ejected into the propeller (just before it completely shattered).  One of the propeller blades ripped through the front shattering it.  Fortunately it was still in one piece.

OK, it's in one piece, but how do I fix it?

Some Google searching came up with a solution that I decided to try. This solution involved using tape to hold things together while thin CA glue is used to repair the cracks.

Another view of the tape

Taped up

So, here I go.  These two photos show the clear tape that I used to cover and hold together the cracks.  The tape also allows you to see better the extent of the damage.

CA applied

Finished product

It's maybe a little hard to see in the photo on the left, but all of the cracks have been run over with regular thin CA glue.

The photo on the right shows the finished product after the tape has been removed.  Yes, it does look like it has been welded together, but it's together!  There is also some clouding of the plastic near the glue (you can see a little of it covering the pilot), but I should be able to buff some of it out.

While this appears to have worked very well there is one thing that I would do different.  If I have to do this again (and I'm sure that I will), I would tape it on the outside and glue it from the inside.  Why?  Well, the taped side left a nice smooth surface (surprisingly, the glue did not stick to the tape) while the glued side, well, feels like a raised weld seam.

Any way, I'm still very satisfied with the results.  Especially since it saved me from buying a whole new cockpit (plastic, foam, and pilot).

Thanks for stopping by my blog.  Please feel free to post comments, good or bad, and be sure to come back and check for future posts.