Catapult launched glider: Sotich 8" CLG

This is a catapult glider design by Charlie Sotich. It's a quick n easy build and flies reasonably well. The plan is available from the Aeromaniacs site here (click on the pdf symbol next to Catapult!).

This one took me just over half an hour to make and came in at 2.7g including nose weight. Not bad for an 8" span model. She flew right off the board with an in built left turn. First flight was a promising 36s in cold weather, 8mph wind.

Alas, after about a dozen flights, I pulled the elastic back too enthusastically and shredded the right wing - the curse of small CLGs! I'm oddly pleased because it was the wood that failed, not the glue joint.

Great fun while she lasted.

All was not lost, as I decided re-utilise the fuselage for another, different, wing and see what I could learn from that






So here she is the next day with a conventional 3 panel wing made out of 1/8 balsa. Also now sporting carbon fibre tow on the sides to keep the fuselage stiff. Weight has gone up to 4.2g, but she still flies well. Polyhedral is 1 3/8" under each tip. Too much, because she Dutch wobbles in flight, but at least showed no tendency to spiral in.







Here's a photo of the underside. You can see the Al-foil tape that I've used to reinforce the wing-fuselage joint. So far, no more shredding!

I think the original is prettier. The modified version seems more consistent. Best flight today was just under 45 s in winter conditions, with no flights under 30 s.

Rapier Rocket Car / Test Rig

Just got my sticky mitts on some Rapier rockets. I've always wanted to make a rocket-powered glider. Another project for next year...

I've never used these rockets before, so I built a test rig for my son. OK, it's a car, but the spoiler counts as a wing!  Inserted a stick-like fuse into the hole at the rear, lit it and then watched it fizzle out. Left it for a while, then tried again. Eventually, it ignited and whizzed off leaving a satisfying trail of smoke. I must get an electric igniter. It has a hot tip: insert in the hole to start the rocket. 

Model Glider Plans

If you're looking for really interesting A/2 glider plans, then the January 2007 issue of New Clarion is a great resource. It contains fabulous information on a number of, shall we say, "nostalgic" glider designs. A/2 gliders are basically the big ones - usually between 60 and 79 inch span (~ 2m). SAM 1066 is a UK based chapter of the Society of Antique Modellers - well worth a visit and their membership is free!

Converting a free flight glider to radio control RC

Free Flight gliders could be useful starting points for an RC conversion - to make a really high performance radio control glider. To flesh this out, here's an example of enlarging a Keil Kraft Soarer and converting it to RC (discussed on the RC Groups forum) :


And here's a super example of an RC conversion of the Lulu (50" free flight glider, discussed on the SFA forum, by my friend Eagleone):


I would suggest that neither the Soarer nor the Lulu is in the same league as the big A/2 gliders. Indeed, I daresay that converting one of those "biggy" free flight A/2 designs to RC would create a very high performance radio control sailplane.

If only I had the time to try it....

A Story about Pre-Flight Checks

Had to take a break from building the P-51D - birthdays, family stuff and such. In the meantime, here's a little tale.

When flying radio control, I try to be diligent about pre-flight checks. However, a month or so ago, I came a cropper while flying the STARLITE (see photos).

Picture this: after changing the prop and replacing the battery with a more powerful plant, she was flying beautifully, save for a noisy (definitely broken) rudder servo. I replaced the servo, and while testing on the dining room table, was delighted that the rudder operated as quietly as the elevator. Charged her up and excitedly, went off to the field. Did my checks and launched from a throw. She climbed a bit then - spiral dived to the ground! I checked rudder centre trim setting, it seemed ok, so I launched again.

Painfully, she spiraled in once more, this time losing a leg and a suffering a bit of minor damage to the fuselage.

What to do? I checked alignment of all surfaces. Nothing except an ever so slight warp on the rudder. Surely the spiralling could not be from that? With the plane pointing ahead of me, I waggled the stick.

Then I saw it. The rudder was moving in the wrong sense! I had done my checks the first time with the plane pointing towards me (and without engaging my brain!). It took 5 seconds to reverse the new servo from the TX switch, after which she flew beautifully (although now with one leg - fine practice for holding off on landings!). When I first heard the story of the pilot who chucked his radio control glider off a ridge, only to realise he hadn't turned the receiver on and then watched it fly off into the distance out of sight, I used to wonder "how could that happen?". Now I understand! For me, repairs were cheap and easy but I hope the valuable lessons learned last forever:

- Always take care over pre-flight checks. Do them PROPERLY, especially when excited about the flight.

- Never assume that a replacement servo operates in the same direction as the previous one. Check it!

P-51D Mustang - Fuselage and tissue covering

For some strange reason, I chose to use normal domestic tissue instead of the usual (and better) Japanse Esaki. This was white stuff from the local newsagent shop, pre-shrunk with water. This is my first effort at colouring tissue. Here, I'm using some very old art charcoal that's been lying around at home for over 15 years! You can also use coloured chalk. Loads of colours and tints are possible.

Simply rub it on, then wipe about in circles with a soft tissue until it's evenly shaded. I did both sides. In the photo, a strip of the original white tissue is on the left and a gey coloured piece for the wing is on the right.

I am not an expert builder, but I enjoy it and do take pride in my work. Below, fuselage sides going down. I'm building both at the same time (this is NOT the same thing as the second one over the first!). Don't bother with cling film between them - you can separate with a razor blade afterwards.














Assembling box fuselages can be tricky and fiddly. Cardboard formers - lightly tacked in place with CA glue - are tremendously helpful. Generally, I use woodwork PVA for all balsa joints and avoid CA except for the places where it's really advantageous, like for the formers here. The photo below is just before the sides were "cracked" to bring the back ends together.




Another view of the fuselage assembly and card formers. They are from a pizza box.












Here are the wings glued up and setting at the correct dihedral angle. This newsagents shop tissue is nowhere near as easy to work with as Japanese Esaki. It does make a change to use a material with a different texture though. The grey colour is just what I wanted - simulating the metal of the full-size. I will have to lightly dope it, to fix the charcoal in the tissue. Note the slightly graded colouring on the fuselage side - the top is grey while the bottom is white. I wouldn't have the patience to build proper scale models, and chapeau to folks who do. Sports-scale is good fun though - it's like a nod and a wink to the original full-size shape.

P-51D Mustang - Sport Scale Rubber Model

The P-51D Mustang is a very popular model aeroplane subject - and for good reason. The sight and sound of one in flight is just as iconic and neck-tingling as the Spitfire. The P-51D is recognisable by its teardrop bubble canopy, fin gusset (although not every D model has one) and distinctive "kink" in the wing LE near the root.

www.mustangsmustangs.com is a superb resource for information on these amazing planes. They served in air forces all over the world.

For some time, I've been wanting to build Dick Baxter's 14.5" sport scale rubber power design, plans for which are available at SFA. You can see the relationship of this design to his Akro model. It's a fairly simple to build rubber model that can be flown outdoors or with care indoors. All you really need are some 1/16" square spars, a bit of 1/16 sheet and a 1/8 square spar. Clearly, he has tried to avoid tricky building and curves while at the same time, creating a fair impression of the full-size plane. It seems like a well thought out design.


I started off with the canopy. This is the first time I've ever tried to hot-stretch canopies out of discarded packaging plastic. It's great fun!

Airframe is fairly easy to build, though a bit fiddly. Here are the wings.

More pictures to follow.

Starlite 36" Radio Control

Site Changes Frequent visitors will note the slight change of style to this blog and the new title. I wanted to broaden the coverage and more accurately reflect my aeromodelling activities.

Flying the STARLITE After giving up on the 150mAh 9.6V NiMH battery and replacing it with a 400mAh 7.4V LiPo, the performance was transformed. She climbs better and keeps going much longer (25min).

These photos were taken by my 6 year old son. I'm quite proud of him and them. Evocative lighting, dew on the morning grass in the one above. Since the photos, I've added shiny aluminium foil windows to the cabin and day-glow orange stripes under the wing (directly beneath the black top wing stripes). Both are to assist visibility in flight. More pictures later perhaps.

Starlite, by Sig / Herr Engineering

So I've been dabbling with the "dark side" again. Yes, radio control, but at least it is a balsa and tissue model - 36" span and very "free flight like". I won't say any more, just show you some pictures instead. It's a lovely, beautifully laser-cut kit available from Sig/Herr direct. Exceptional value for money, especially wood bag and plan.

Do you remember your first ever model plane?

I do. I get the feeling that many (if not all) aeromodellers do too. Yes, the memories are hazy. I wonder how many of them in later years decide to build their first model again? For me it was a small 24" tow glider called the CROFTER by Ian Barrett published in Aeromodeller in 1973.

I built it during an after school club run by my teacher. Recently, I located and bought the plan for it. How weird to see it again? It's like that feeling of going back to your old school after many years - everything seems smaller and simpler than it did as a child.

I also remember the frustrations at the time, because no one explained how to trim and fly it properly. It is a simple design with Jedelsky style balsa sheet wings and 6mm balsa fuselage. Should I build (again) it or leave it for my son to cut his teeth on? Actually, it would be fun to strap it to a rocket motor! Now that's an interesting idea....

Andy Crisp's World of Free Flight Model Aircraft

If you've ever met Andy Crisp, you would know that infectious enthusiasm which he has for free flight. What a character! Now Andy has just published a new book. It's one of those instant download e-books and is available at the bargain price of £2.99 from http://www.instant-books.org/

I've bought it and the transaction was smooth. I received the book in a 47 page long pdf file. The book includes many plans and notes of gliders, hlg, clg, dlg, power and rubber. It's really great to see this book - it is not only a record of some of Andy's fabulous models but also a really encouraging e-book project from Instant Books.

I wish you every success!

Video of discus launched glider DT

I've not been able to fly Lipzoid much (or blog for that matter). Here's a quick view of how the glider's dethermaliser operates. In the video below, the DT timer triggers at about 3 seconds in. It brings the glider down, but could be improved (and I have some thoughts on how to do that). The second video is a rare event captured on camera. Watch out for the kite flyer near the end and sorry for the dark skies!

Model aircraft building board heals itself!

I started to build a model aeroplane on the building board (see the May 2008 post below). The plane is a 1m electric job. I have to say that this is the best building board I've ever used. It holds the pins with just the right grip and "feel". However, stupid me, for using thick brass thumb tacks (or as we call 'em "drawing pins") to pin the plan down. The next photo below shows what happened to the balsa block underneath:

As you can see, the thumb tacks left significant holes and dents while the proper modelling pins (pink ones in the top photo) left negligible fine holes. However, after a quick wipe with a wet rag, the balsa healed itself "organically" in just a few minutes:

Wow, that's cool! As you can see the drawing pin holes closed up a lot and the dents have gone. completely The modelling pin holes were not an issue anyway, but even they have virtually disappeared. I won't be using drawing pins again - I've found some finer map pins for holding plans down. Proper modelling pins are well worth buying. These are Czech ones, from Flitehook.

Who says wood is dead when it can still heal itself like that?

Building Boards

My building board is knackered (for those not familiar with English slang, just read "unuseable"). A good building board is an essential piece of kit for the free flighter. The requirements are simple, it must be:

• flat
• easy to pin and grip pins well
• big enough for your needs - long wings, bigger board

Some people are lucky enough to find a suitable fibreboard, blockboard, soft timber board or other ready made sheet in their local DIY shop or hardware store. I searched all over and could not find anything suitable. So I decided to make my own and here is the build sequence. It did not take long and cost me less than £10.




I used hard 15mm balsa planks, 4" wide mounted on a flat chipboard backing (an old bookshelf).

The planks and the chipboard were evenly coated with contact adhesive.











After 10 minutes, the planks were glued down to the chipboard. In addition to the contact adhesive under each plank, PVA glue was used between the edges of each plank. The excess PVA was wiped off with a clean damp rag.








The whole thing was weighted down overnight while the glues set.












Here is the finished board, trimmed and sanded flat. It takes pins well with good grip.


Now, what shall I build on it....?

Model gliders - all Chuck Gliders - Old and New

Here is a photo of 4 hand launched model gliders. In a way, they represent many decades of aeromodelling between them. Anti-clockwise from the top right:

• 20" span vintage HLG by Bowers from the 1930s. This is the oldest polyhedral design HLG that I'm aware of. This one has a drinks can aluminium side flap dethermaliser (DT). Build information is shown elsewhere in this blog. Since then, I've maxed it (>60s) a number of times.
  

• 14" span vintage HLG from a range of books entitled Newnes Pictorial Knowledge. This seems to be from the 1940s and is a good basic all balsa design. I found it in a SAM35 year book.
  

• 8" span HLG based closely on Kevin Moseley's excellent LET'S ROLL design (bamboo "kebab skewer" fuselage instead of carbon fibre and dihedral angles are slightly different). This one flew out of sight on its maiden flight (literally the first hard throw). It was found months later many miles away - always write a mobile phone number on your model! When I picked it up the wing was fine and it still flew, but the tail needed replacing.
  

• 36" span tip launched glider LIPZOID. Its design and build is shown in this blog below. It follows the recent discus launch developments and I suppose represents the modern era of chuck gliders.
  

DLG Plan: Part 6, Finishing the glider

This photo of the finished glider - LIPZOID - was taken just before its maiden flight. See the video in Part 5 below.

Parts for the left side of the fuselage. From the left: 1/16" ply, 3/32 balsa (the hole is for the DT viscous button timer - I modify the basic cheepo buttons available from Flitehook for £1.50) and 1/16" balsa. Edges were sanded so that the surfaces blend together smoothly.

After the front of the fuse is finished, I cut out the wood boom block (pine) and measure out and cut the rear of the fuse.

I ca'd a bit of thin clear plastic to reinforce the rear of the fuselage, as this will come into contact with the spruce block when the boom is up. This was then trimmed and cleaned up.

This is the pine boom block ready for gluing with ca. Then it was glassed with the cloth running round the 5mm carbon fibre tube.

Ready for drilling. It was quick and easy to drill the pine boom block first. Glued one 1/16" ply cheek and when dry, marked and drilled it. Then did the same for the other ply cheek.

Wing being glued to fuselage. I simply sanded the top of the fuselage flat to mate with the wing underside. However, because of the upsweep under the LE, I also made a small wedge shaped balsa piece to match the space between LE and fuselage.

This is a close up of the wedge under the LE.

Close up of the finished boom block socket.

Glass cloth was applied to wing joints - two 2" squares, one over the LE and the other over the TE, plus a strip top and bottom. Lightly tacked with a spray glue, ready for resin to be sparingly brushed on. In addition, the left wing was given extra reinforcement in the form of oval patches in the middle of the joint on both surfaces (not shown in this picture). The centre wing-fuselage joint was also reinforced in a similar manner.

Detail of rear of fuselage. The gf cloth reinforcement is visible as is the nylon hing bolt. I used two transparent hair bands around the boom (Lark's Head knot) looped over a bamboo peg in the middle of the wing. The yellow band is thinner pole elastic for the timer.

Detail of the boom arrangement. Pink band is 1.6mm pole elastic, tied (Surgeon's knot) to the thinner yellow elastic. The yellow is tied to nylon fishing line with a small loop tied to the end. The loop is hooked over the timer arm. Coaxing it to operate reliably (one turn of the arm should take about 1 minute) is good fun and surprisingly easy. Under the wing the pink elastic is tied to a steel pin head and run round two cocktail stick pegs. Also, you can just see the adjusting screw for decalage.

Glider with boom in the up position. Just numbers (BMFA and mobile) to apply. The finished model without ballast was 83 g, a bit heavier than I would have liked. I definitely overdid the glassing, especially on the tail. On the other hand, it's pretty strong and I reckon it will need to be because it's going to get a good bashing!

I enjoyed this design and build process. It is always amazing to see one's model fly. LIPZOID seems to be fairly stable with hardly any trimming effort so far. My tip launching was not very consistent, but thankfully, the model recovered from most of the scary attitudes. There was one very heavy landing, but just a minimal repair to the right wing was needed (I knew that was going to happen because there was a natural softer spot in the wood there). I'm now waiting for good weather to have a decent trimming session. I'd like to try increasing the decalage and perhaps moving the CoG more forward. It's at 50% at the moment.