cchariandy

I have been looking for a first pattern plane for my Son for quite some time and eventually decided on the Spot on 50. However, I had difficultly finding good build logs to assist in the decision so I am going to post one here.

The initial target was to get a capable starter pattern plane that was reasonbly priced and so less stressful if lost. Additionally, I wanted to re-use the engine from my sons trainer, an OS50SX, so an all up weight of 5lb or a little less was needed.

I ordered the kit from Airborn models and it arrived in Canada just 2 weeks after shipping, well packaged and in good condition.

The kit quality is not great but there's lots of value in the box and the design is quite modern compared to others like the Venus 40, GP Tracer, Kaos etc. And unlike more expensive kits like the Oxalys all flying surfaces are airfoiled. The hardware is very good and looks like Tetra copies however the landing gear and fiberglass work are very heavy and the horizontal stabilizer is a bit warped...hopefully we can trim that out. I have also asked AB models to replace it. Their service has been good thus far I hope they agree and send me a new one.

Update: AB models agreed to send a new stab after seeing the photos of the one I have....great support. I'll add pictures of both stabs when I get the new one.

I plan on replacing the wheel pants and landing gear and will make the cowl lighter after carving it up to accomodate the engine.

Here's the equipment I'm going to use and extra stuff I'll replace for weight saving and performance.

OS50SX, standard muffler, dubro extension.
Dave Brown 50-60 mount
9650 - Ail
9202 - Elev, Rudder
HS85BB - Throttle
TP1350 - Rx pack
Central hobbies DEPS - 0.07" Elevator control pushrods
Hobby City 160mm Carbon Gear
Hobby City 90 size wheel pants
GP 2.5 spinner with light back plate
Central Hobbies Aluminiun axles

I started with the engine installation.

The airplane comes setup for an inverted engine istallation with blind nuts pre-installed but I wanted to mount the OS50 at an angle to allow the standard muffler to exit at the bottom. My Son is not the best at airplane clean-up so this is a must. Also, I bet the covering (Toughlon) will benfit from having less oil thrown on it.

The supplied adjustable mount is very heavy and too large to be installed across the firewall so I removed the existing blind nuts and installed a Dave Brown OS50 one piece mount. I had to reach through the opening in the firewall for the fuel tank to install the new blindnuts.

The mount was a bit short so I installed the two aft screws only...don't freak out, this is done with hyde mounts with no problems. A pair of SS 6-32 screws have more than enough sheer strength for the job.

I used a Dubro muffler extension and carefully butchered the cowl to accomodate the muffler. I didnt mind as we'll benifit from the weight reduction anyway and I don't think the end result looks badly.

I'll add pictures later (if I figure out how).

cchariandy

Here are few pictures...

The DB mount fits perfectly between the pre-drilled holes so there's no problem placing the engine on the intended thrust line.

cchariandy

And few more showing the final fit of the cowl and muffler. I replaced the 62mm plastic spinner with a 2.5" GP spinner with light back plate. It fits better than the 62mm spinner and is a bit lighter.

cchariandy

The kit came with plastic servo mounting panels for the ailerons. They are a bit heavy and don't fit the 9650s so I built a new pair out of some scrap composite board left over from a Comp ARF Integral. The board is just the right thickness (2mm), very light and already painted.

cchariandy

The wing panels use an aluminium tube spar and anti-rotation pin similar to plug in wings however they have to be glued together to make a one peice wing. Epoxy is applied to the tube and root rib area and the assembly clamped and taped together. You don't need tons of glue here as the fit is quite good and you don't need to fill any gaps. I used Z-Poxy finishing resin instead of 30 min epoxy.

cchariandy

Though this is one of the least expensive 50 size pattern ARFs I can find it's very well designed with lots of effort made to keep it light. Here are a few pictures of the interior of the fuse showing some of the details.

cchariandy

And a couple more....

kcc

Hi,
I'm enjoying the threadthanks for posting your experiences. I got my kit yestereday, and can't wait to get started. Did you weigh the components before you got started?
Thanks,
Kevin

cchariandy

Unfortunately no...I don't have a good scale for small parts. I will try to post finished weights of the wing and fuse.

Colin.

cchariandy

I positioned the fuse to ensure that the sides were vertical and checked the fit of the fin...close to perfect, no need for any adjustments. I glued the fin in place and re-checked the alignment.

cchariandy

With the fuse sides vertical I ckecked the fit of the wing. It looks like I'll have to trim the left side of the saddle to move the wing about 4mm just inbd of the aileron. Nothing too drastic. I'm liking this plane more everyday.

cchariandy

I found a reasonably accurate scale in Canadian tire and decided to quantify some of the weight saving changes I made.

1.2 oz were saved on just the aileron servo panels and the spinner. I'll continue to make comparisons as the replacement hardware arrives.

cchariandy

I sanded the saddle and re-checked the wing alignment. It's not perfect yet but I discovered that the wing is also warped. I hope I can take some of the warp out by re-shrinking the covering.

cchariandy

I found the left wing panel to have 1.3 degrees more incidence at the tip. Luckly, I was able to re-shrink the covering while twisting the panel and most of the warp has been removed. I hope it stays in it's current position for the entire season. This is a very low cost airplane and I think a few quality related issues are acceptable. At least the ones I have run into up to this point have been correctable with little effort or cost.

The last picture shows the final position of the left tip...only a little off.

Jetdesign

My Feedback: (8)

You pattern guys with your fancy work spaces, tools and materials...

I hope I end up just like you

Plane looks very nice.

cchariandy

I finished the rudder installation including the pull-pull and servo. I like the hardware but found the cable gage excessive and difficult to thread through the fuse...it kept curling up. I had some extra Du-bro pull-pull cable laying around and replaced it. The horns are little too far fwd so the trailing cable is running a little slack. I may change the servo arm to a wheel with some offset to correct it....maybe, it's not that bad.

AB sent me a new stabilizer...got it in the mail today along with Rx pack I intend to use. The new stab is much better than the first so as far as quality is concerned I'm quite happy. We'll have to see how the plane trims out after the first few flights.

The Rx pack is another good way to save an once or more while improving performance. The SR pack is a 900mAhr 6V Metal Hydride, the LiPo is 1350mAhr 7.2V and the rgulator is a 6V Jaccio.

Incidentally....after I "un-twisted" the left wing panel all my measurements for horizontal alignment were crap. I basically had to put back everything I sanded away at the saddle. That's why there is a ply plate on the hold down area. The lesson here is to take all warps out first, then start alignment and set-up.

cchariandy

I finally got the wing and stab aligned and have expoxied the stab in place. I used Z-poxy with micro-balloons. It's difficult to change the position of the wing as the hold down screw holes are already drilled but I checked the alignment anyway....all are pretty close.

kcc

Colin,
I looked back at my previous post and realized I misspelled TWO wordsit must've been a bad day. Would you consider trading my kit for your completed plane??? Seriously, I hope mine turns out as well.

kcc

Colin,
I looked back at my previous post and realized I misspelled TWO words. It must've been a bad day. Would you consider trading my kit for your completed plane??? Seriously, I hope mine turns out as well.

cchariandy

Just take care of the warps before you start. I wasted a quite some time sanding the wing saddle and then had to shim it back after I took the warp out of the wing.

The plane is not bad looking....we'll have to see how heavy it comes out and how well the little OS 50 flies it.

Colin

cchariandy

I finally got the DEPS (carbon elevator pushrods) from Central and as suspected there's another once saved. I got the throttle pushrod done making use of one of the old engine mount screw holes. I used an HS85BB for the servo.

I started the tank installation and found that it has to be installed inverted with respect to the instructions to properly line up with the opening in the firewall. My hands cramped up trying to work in that tiny space so I started on the DEPS installation. Very smooth operation so far. I just cleared both openings at the supporting tube. The carbon rods are the same size as the original steel rods so the fit is perfect.

cchariandy

The weather here in Ontario has somehow improved (in March???) and we spent the last few days flying our small elecrtics so I have'nt gotten alot done. However, I did get the DEPS completed. It's very smooth and the elevator halves are rock solid. The control horn screw positions were perfectly marked and the kit comes with two different length screws for the ailerons and elevator....of course I didnt realise that until after I had the first two installed.

The tank installation is done and the cowl back in place. I used a foam block above the tank for a tight fit and sealed the covering edges at the firewall with epoxy. The firewall is already fuel proofed.

Added a little a neat needle-valve extension.

I'm going to start the radio installation and hope that we get the landing gear soon.

manyu

Hey Ccharandi,

What a beautiful plane... I have been lookinh to buy this plane for the last 3-4 months but its not avaiable with the distributors in the uk... Beeen looking at the build page closely..Keep the pics coming.. ! Let us know how the test flight is??

cchariandy

I glued the canopy in place using RC56, finished the aileron controls and added the tail wheel assembly...quite a nice one for low cost 50 size plane. I didnt like how slack the trailing rudder cable was running so I replace the servo arm and added 2-3mm of offset. This worked very well. I liked the foam block for the Rx, I dont think I can build a lighter version so I'm going with it.

The plane now weighs 4lb, 11oz and still needs the battery/regulator and switch harness (another 4 oz) and the gear (3oz) so an all up weigh of 5lbs is not possible but we'll be close. I think AB models advertised all up of 5.3lbs is going to be tough to achieve for a stock plane using the even the lightest 60-70 4-stroke. I have taken more than 7oz out of the stock build and will only just beat it.

Without the gear the plane balances at the recommended CG and there isnt much room to mount the battery any further aft so I'm pretty sure we'll have to add a little tail weight...we'll see.

I'm just waiting on the gear now then I can finalize the battery and switch installation and minimise tail weight. Maybe another week or two to the test flight.

cchariandy

My previous weight was wrong...it's 4lb 14.6oz so the estimated all up will have to be 5lbs 6oz. AB's estimate of 5lbs 5oz is not possible.

Here are some of the weight savings:

Aileron servos (9650 instead of standard) - 1.4 oz
Servo covers (home made instead of plastic) - 1oz
Deps (carbon pushrods instead of steel) - 1oz
LiPo Rx pack (instead of NiCd) - 1.5oz
Os 50 2 stroke (instaed of YS63) - 2oz
hobby city gear (Carbon 30gm) - 2oz
DB engine mount - .5 oz(estimate)
Spinner - .1 oz

I still think it's not a bad weight for this size plane, 538sq ins. The test flight should give us the right feedback.