Gangster 63

[Martyn K]

I managed to wreck my Astro Hog at the UKCAA Sleap Fly-in when I appear to have had an in-flight power failure..

The model was beyond repair so a replacement was needed pretty sharpishly. I had previously owned 2 Gangster 52 powered by a HB40 Silver Star and I was delighted with them. I had my eye on the Gangster 63 Lite for some time and just needed an excuse.. The (old) Gangster 63 was also the reference model in the old MAP Flying Aerobatic Models booklet that was published in the late 1980's. I thought it would be interesting to see how mine would compare with the original.

This isn't a build blog, for one reason, I have actually finished the model so it's a retrospect. There is already at least one other Gangster 63 build blog on this forum and it seemed pointless to repeat what had already been said. This retro-blog therefore details a few tweaks and changes.

This is a big model and I was amazed when the power recommendation was 20-40 sized. With more wing area than my Magic, I could not believe this could be aerobatic on a 20. A couple of PM's with Jim Carrs who had already built one and it seems that a 46 would give a lively performance. I also just happened to have a manifold and tuned pipe for a 46 - I mean it would be rude not to wouldn't it?

So the box arrived..

The first thing I couldn't find was a plan.. a check through the contents list and the colour instructions and the omission was deliberate. This model goes together like a 3D jigsaw - it all interlocks and you simply run cyano into the joints. I don't do cyano for structures - I settled for my usual PVA.

All parts are really well laser cut - using mainly thick balsa sheet. Very little 1/16 sheet on this model - just the D box LE and centre section sheeting.

You simply slot the ribs into the holes in the laser cut full depth spar and click into position. it is so well cut you really don't even need a building board or a plan.

Some of the ribs have little building tabs so you can check the wing is straight.

A couple of evenings work and the wing was mainly built. A couple of minor alterations - I choose to use my Kevlar strip for hinges - this needs a sandwich forming with the Kevlar in the middle.

One mistake that I did make was that I placed the outer ply rib doublers on the wrong side of the rib - should have been on the inner edge. The ply plates that support the undercarriage are joined in the centre and form a large dihedral spar/brace. As the doublers were now on the wrong side, they u/c plates needed extending about 6mm on each side.

Not a huge problem but it wouldn't have happened if I had a plan or at least an exploded digram..

Fuselage sides were formed from more laser cut pieces. Note - no ply doublers on this model. I was getting very nervous about just how strong this was going to be..

It doesn't need a jig - like the wing, however, I wanted this to be straight so I built it in the jig anyway.

Again - a couple of evenings and was built

More to come...

 

Martyn

Edited By Martyn K on 06/06/2014 23:13:49

[Masher]

Hi Martyn

I'm watching this with interest - especially to see what changes you make and the power plant chosen

I bought one of these already built (very well built) as airframe only, not yet fitted out or flown. My research came up with Irvine 53 as ideal choice so keen to see what you put in and how it flies

Martin

[Old Geezer]

Following with great interest - back at the end of the 70s I had a Gangster 63 - it still remains the one of which I have the happiest memories. I am very tempted, especially as it is so light, to put a big lazy outrunner on the front and do all those effortless aero's that were the G63's specialities.

[Bob Cotsford]

It looks as though there are balsa doublers in the nose so it should be fine Martyn. One thing I've found with not having ply doublers is that engine bulkheads get knocked loose more easily but it results in less overall damage and easy repairs.

It does sound a big model for 20-40 engines, but then so was the Hog.

[Jimbo565]

Looking good

[kc]

The Mick Reeves website says the 63 lite can be flown on .30 to .40 size engines in one part  but another section shows 20 to 40 which I suppose is a misprint

I would bet a really good .30 two stroke such as an Enya 30SS would fly it if Mick Reeves suggests a 30.

Edited By kc on 07/06/2014 10:43:38

[chris kearney]

I have been wanting to build the Gangster light for a while, watching this with interest, I can't make up my mind weather to build an electric version or put my English built Irvine 46 in it.

[Jimbo565]

Did my A cert with mine,as soon as the test was over the examiner was straight there " Giz a go on that gangster Jimbo" thats my type of model,he was delighted with the performance ( 55AX up front)

Still my favourite model.

Only down side with the kit is the flimsy ABS cowl

[chris kearney]

Anyone built an electric version?

[dave parnham]

haven't finished mine yet, but it has an Irvine 46 up front, seems about right to me.

[Martyn K]

As mentioned above, there are balsa doublers between the front two corners. I added an additional pair of balsa uprights behind the second former to provide a littlee additional support. At this point, I sanded the top decking and started on the fin and tailplane.

I use kevlar cloth for all my hinges. These are sandwiched between two strips of balsa and the hinge is then glued to the tailplane /fin/rudder etc. This meant that I had to strip off 3/8" off each surface. As the supplied wood was very light I decided to incorporate a 1/8 x 1/4 spruce spar in front of the elevator hinge. I have had tailplanes fold in flight before now - not a pleasant experience. I wish that I did the same for the finpost.

The tail surfaces are assembled using precut strip wood in a geodetic triangulated fashion. Again no plan - you simply assemble it and at one point the whole lot just locks together. You need to build this on a sheet of polythene.

One thing that worried me was the size of the material at the fin and rudder extremities. At this point I kept to the plan but I was not happy.

When dry, the whole lot was aligned and glued to the fus. As expected very little alignment was required.

Now with the wing attached, including noseleg the model was weighed. Just over 750gms. This was very light.

Which brought me nicely to my next mistake. The ailerons are built up. Full of confidence with the build process I continued blindly and built a pair of perfectly straight ailerons. The trouble was they should have been trapezoidal..

A little bit of rework was required.

[Martyn K]

With the airframe finished and ready for covering, I had a close look to see where I could add reinforcement without impacting on the weight too much.

I added additional webs 3 bays out from the end of the undercarriage plates to remove an obvious stress discontinuity.

You can see in this shot the ply plate stuck on the wrong side of the ribs.

I also added webbing across the upper longerons - grain transverse to stiffen up the fus.

This has added quite a lot of strength for very little additional weight. I have also added cap strips onto the upper dormers. This is mainly to give the covering something to stick to.

Finally, I used lots of the little triangles that came out of the spar as additional gussets at various locations. The other area where I added a little

E extra strength, I doubled the wing seat area.

Showing the thickened seat and radio installation. The seat is only about 10mm deep so very little weight gain here.

The rudder showing the triangulation used in the construction. I mentioned that I was very unhappy with the size of the material at the top and bottom of the fin and rudder. I could feel the rudder flexing as I covered it so decided to add additional gussets top and bottom before I covered the other side. Not the best planning in the world.

Jim has mentioned that the supplied cowl was very flimsy. I chose to build a cowl out of balsa. Basically, there is a liteply subframe at the back screwed to the firewall and a spinner sizwed disk at the front. I simply plankedf it with 3mm balsa with 6mm balsa at the corners. Carved then sanded and fuel proofed.

[Martyn K]

As mentioned in the OP, the model is finished.

And

The cover is a mix of or a cover and solarfiilm polyester with solartrim to add colour.

I maidened the model on Friday evening and it needed a couple of clucks of up trim and a click of left trim. I haven't weighed it yet but I expect it will be around the 4lb mark. Vertical performance is impressive, the model was very neutral. Bunts, rolls, spins, stall turns, loops etc were very easily perform ed although it was a bit twitchy on aileron.hopefully this will get cured with a mix of rates and expo.

It certainly doesn't want to land. If the tickover is a bit fast the best you can hope for is a very shallow - almost horizontal glidepath.

A bit more to come..

Martyn

[Rich too]

Nice, I always fancied a Gangster. What happened to the cowl and tuned pipe?!

Rich

[Former Member]

[This posting has been removed]

[Martyn K]

A few more photos..

Rich - well spotted. I took those photos (poor quality) just before I made the bracket for the pipe. Its moved on a bit since then (but not much)..

A shot of the airframe when I weighed it. I thought that the noseleg had been fitted.

The tail. You can see the spruce spar inlaid in the tailplane and the construction of the fin and rudder. You can also see how little wood at the top and bottom of the fin and rudder assemblies. There is also a surreptitious gusset that has appeared at the LE foot of the fin and 2 more at the LE of the tailplane where it joins the centre plate. This shot was taken before the upper deck sheeting was added (obviously).

Fus - front end. The wrongly placed ply undercarriage/rib doubler can be seen, it should have been on the inside edge of the rib..

A much sharper shot - just before the cowl and pipe was fitted

Ready for the maiden flight. I still haven't covered that cowl yet but it will be done before GreenAcres.

BW

Martyn

 

 

Edited By Martyn K on 09/06/2014 12:28:14

[John Emms 1]

Having built and flown an original Gangster 63 powered by a Merco 61, I have the phone number ready to order the Light tomorrow. The lack of plan is deliberate, as all UK kit producers suffered from including full plans, as the plans would then be passed round, and kit sales dried up - making it not worth developing the kit in the first place!

A modern 46 is WAY more power than the Merco, so at this low weight, a 46 is clearly going to be storming.

The Light is clearly aimed at electric, and as I have either given away, or thrown away all of my glow "stuff", mine will be electric. I have powered so many similar size and weight aerobatic models, including our own Super Skylarks, Wildcaps, and my Okapi, the Gangster will get similar power.

I have one question, and that is what prop size will the model reasonably take? Yes, I know the UC can be made longer, but that takes valuable living time!

Regards,

John

[Denis Watkins]

Martin and John, as you both have interest in this model being both IC and Electric. The .20 - .40 label is not far out, at 4lb weight, when you think a .20 can put out 500 watts, and the 46 could achieve1200w with ease, so bear this in mind with the electric. Am sure the IC version will cruise around solidly at half throttle, with loads to spare for "flying"

This lightweight large airframe is ideal for a number of Electric set ups, with one avenue being elongated flight times with a modest set up, and short swift flights for those that need it

[gangster]

Mine is electric about 675 watts on a overlander 3548 and 4s. As for that cowl. Yuk t rashes 2 and refused to pay £10 for a third so rebuilt it using epoxy and covering glass cloth. Have now got a strong light glass cowl. Lovely model flys as well as proper gangsters

[John Emms 1]

Well, I just placed the order by e-mail, and I will phone in card security info tomorrow.

I guess the answer for the cowl is to use the original as a mould, and get out the lightweight glass.

I must admit to being very surprised by the 4lb weight that is being quoted.

The reason I ask about the prop clearance is that systems we have used in this type of model have used props of 14", 13", and I have been using 11" on 4S very effectively. Even my 60" Okapi when flying at 4.5lb was fully aerobatic with 10" props and 3S equivalent (right on 40A, around 400W) - I didn't believe it would work, but it had to be tested. If the Gangster will take 14" props, then yes, it will take a huge range of power systems.

The original Gangster was an incredibly pleasant handling model. Irvine .39? - go for it Percy!

[Denis Watkins]

Just look at the lightweight build John, there are more empty spaces than timber, and the thinnest sections possible, all a result of laser cutting tech. These lightweights are a joy to fly as they can be adequately powered and equipped without lightweight servos. I am a fan of laser kits.

[gangster]

The lack of plan is deliberate, as all UK kit producers suffered from including full plans, as the plans would then be passed round, and kit sales dried up - making it not worth developing the kit in the first place!

Well the original Gangsters never had a plan but they only had about a dozen bits of wood in anyway. Modellers regularly drew around the components and copied the models like that . The lite however has about a million lazer cut parts and I cannot imagine anyone having the patience to copy them.

Prop size John well I have had a 13 inch prop on with no problem, a 14 inch would clear but it would be very close!

[dave parnham]

Mines still flying and goes very well on the Irvine 46, only bit on the build that throws most people is the fit of the Ailerons they are just not quite right somehow, but easy to fix.

Must admit that I had a fuel tank leak, or cracked pipe at least, and it somehow corroded the battery lead.....well I started the aircraft and it ran on the the ground for 30 seconds then cut, and again and again. Turns out my Tx was doing its job and telling me the battery was now dud and wouldn't let me fly it. Model Saved...lesson learned.

[John Emms 1]

Thanks on the prop sizes Gangster - that opens up a whole host of possibilities. No, I won't be tracing round the parts!

Denis, I spent a number of years on the phone all day, and over the counter at shows, specifying power systems for a huge range of models, and the most difficult part for me was people wanting to power old favourites that were over heavy as IC models, never mind loading the poor model with batteries. Putting high power into smaller props generally meant more specialist motors (read as higher cost). Quite often the low cost answer was to abandon that project, because a new light airframe with a lower cost power system would have a combined price considerably lower. The simple maths are that it takes a certain amount of power to maintain a certain weight in flight, and it roughly works out that halving the weight will double the flight time for the same power system.

Other than, perhaps, Hotliners, I see a small number of Czech designers first getting to grips with the concept of really successful "normal size" electric aerobatic models (the same designers who traditionally produced most of "German produced" models), and of course those methods were taken up by Asian manufacturers. So, 1,5m aerobatic models in the Gangster 63 bracket that I have experience of (that are no longer produced) are:

My Gangster 63 with Merco 61 was 6 1/4lb dry (lost to "period radio" )

Obag Super Lark: We flew these on 14 and 16 NiMh cells (4S and 5S equivalent) at 5.5lb to 6lb, both were a revelation in 2003/2004, and would still be impressive today.

Pelikan Wildcap. One on 5S was truly wild at a little over 5lb. Mine, on 4S 3700 was 4 3/4lb. The 600 size MVVS 4,6/840 on an 11x7 was only peaking at 35A, but gave vertical climb out, and 20 minutes of aerobatics.

Putting to one side my Gangster sized Reichard Okapi, which would appear to be flying at a similar weight to the Gangster Light, you might see just how excited I am that a British kit producer has truly got to grips with the concept of a 1,6m electric aerobatic model (OK, 1,58m). I am buying one, both to support the effort, and also to have a replacement ready for the Okapi (also no longer produced).

Oh, and top tip: When wanting to draw higher currents at higher voltages, it is always more efficient to use a larger motor than a higher resistance smaller motor.

Edited By John Emms - Puffin Models on 29/01/2017 21:21:41

[John Emms 1]

Oops, hope I haven't killed the thread!

The kit was ordered yesterday, and is on it's way today (it could have been here today if I had been quicker).

I have projects to finish, and an Electricub to start, but I have been looking at possible suitable motors. I have a 45mm diameter Roton 600W/12, which is looking interesting, and I guess props for 4S will be around 12x8, but putting a prop and battery on it is the only way to know. I guess balance will be the issue, but as the motor is little more than half the weight of the engines this model is intended for.....