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.

DLG Plan: Part 5, Sneak preview Video!

I will continue the build posts, but in the meantime, here's a sneak preview of the glider LIPZOID in flight today on its maiden outing. It dived off the top of the launch, but stabilised nicely in a wide right turn. Lee Hines commented on a forum somewhere that CoG at 45-50% and a fair amount of decalage works well for him. From the brief flying that I've done so far, I'd agree with that. LIPZOID is not trimmed yet as I only had a bit of time to fly today. The sky was beautiful, but it was getting dark.