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Mike.K

Horizon/Hanger9 Ultra Stick 10cc low wing conversion

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Here is my latest low wing conversion Ultra Stick project which is now complete and ready to go.

A couple of weeks ago I bought another standard Ultra Stick kit from Ali Machinchys` father at Als Hobbies in Milton Keynes. This makes the third one I`ve had from him to date. The first two have been built, one as an electric version with a 5060-420Kv motor running on a 3700 or 4500 six cell and UBEC set up. The second one has a brand new and unused Irvine .72 nailed to the front. I also have a scratch built cloned fuselage fitted with a low time ASP 1.08. A genuine spare wing will be sourced from Munich over the next few days to give it its own wing. Why from Munich? Well, even with delivery charges and customs and UK delivery added, I can make a saving of £36 on that spare wing with the complete and covered "spare part" with ailerons coming for exactly £80. In the UK, the lowest price I can find for that same part, costs another £36. In perspective, given materials and covering costs of scratch building, it hardly makes building a cloned wing a financially viable proposition let alone finding about twenty five hours of personal time required to build it from raw materials.

OK, everyone knows I have the hots on the H9 Ultra Stick ARTF kits which are not only exceptional value at £206 delivered, they fly like a witch, are very forgiving with a wide flight envelope, but best of all, the kit is so well designed and has a large amount of parts included which makes building a standard high wing kit possible in only about eight hours.

Over the past year or so, I`ve looked at a number of internet forums and at YouTube vids. This has given me an insight into the world wide Hanger 9 Ultra Stick scene. It has been interesting to see what other modellers have done with this particular H9 offering. One of the most fascinating models was a standard kit modified to take an I-beam across the engine bearers which was then fitted with two electric motors. Ungainly the model was but boy, did that model do the business when flown. The sound was amazing. Just as interesting was that the modeller was based in deepest Alaska and was flying the Stick in winter half light off a beach covered with foot high snow!

I also tripped over a 2001 vintage article published in the American RCM magazine. The writer, Jim Feldmann had taken one of the early Hanger 9  78" Ultra Stick Lite kits and converted it to a low winger. He then wrote about it for the magazine and included detailed images of the salient conversion points, miniature plans and also helpful pointers for anyone thinking of converting a kit from high to low wing. Google images also showed that several other modellers had also built similar low wing conversions. The Feldmann article gave me the impetus to perform surgery to Ali Machinchys` latest Hanger 9 kit and to get into email conversation with him at the Horizon Hobbies HQ in Illanois where he holds the position of Senior Product Development Manager. Ali was interested in my comments about the standard Ultra Stick kit and was quite amused when I said that I intended to chop a kit about and turn it into a low winger. Now the model is complete, images have been sent to Ali and I`m presently awaiting his comments. I`ve also mentioned that I quite fancied building a high wing, twin OS .40 engine version but that is a subject for another thread.

The conversion was straight forward enough and without any particular issues. I noted Jim Feldmann had initially flown his conversion with a standard flat wing that was devoid of any dihedral. This caused the model to suffer adverse yaw when rudder was applied. Right rudder input would cause the model to roll to the left which was of course rather undesirable. Jim then cut the wing in two and added an inch of dihedral under each wing tip which cured the issue at a single stroke. Rob at Avicraft and indeed our James both thought that adding dihedral would be un-nessesary. I went away and cogitated on the conundrum.  I hated deciding to turn down the advice of Rob and James especially as they are two such experienced guys. Mr Feldmann said in his article that the model improved greatly as a result of the dihedral addition and that the resulting improvement gave the low winger almost identical benign flying characteristics as the original high wing configuration. My flying abilities are presently advanced ab initio at best so I decided to err on the side of caution and give the model the highest chance of survival in my hands that I could possibly manage. So dihedral this model has gained at this point in time. A flat wing can also be trialled at a later date.

The next item that required my attention was moving the landing gear from the bottom of the fuselage to the top. The idea of the conversion was that the fuselage would be stripped of the original H9 covering and simply turned over to provide instant low wing configuration. On the high winger, the landing gear axle line is just behind the leading edge of the wing. Short of building the landing gear into the front of the wing just behind the leading edge, on the low winger I would have to accept that the landing gear had to re-locate forward of the leading edge putting the axle line about two inches further forward when compared to the high winger. Jim Feldmanns model was built to that maxim and he said there was little to chose between high and low wing versions when it came to take off, landing and during ground taxi work. That gave me further encouragement. The Dural sheet, pre-formed landing gear is standard H9 Ultra Stick which on the high wing original, points slightly forwards.  As I needed the axle line to move rearwards on the low winger, I simply reversed the landing gear and put the wheel spats on back to front! A classic case of keep it simple, stupid!!

The thrust angle for the engine was reversed at the front firewall and I left down thrust as set in the high wing kit. Only after examining images taken yesterday, did I note that the engine appeared to have a considerable degree of up-thrust. How I missed that detail, I don`t know but the issue has now been fixed by insertion of a covered 1/4" ply packer inserted between the top part of the two part nylon engine mount and the top of the firewall. The engine now appears rather better zero`d out and the panic packer is almost un-noticable!

The wing was cut in half with a modellers hand saw. Wing ribs and spars are made from lazer cut and profiled 3mm ply. Ribs are notched at the TE, LE and mid depth section to engage the spars during construction. Lengthwise, the two part spar is joined off centre from the centre section with a dovetail joint which is over plated with a section of 3mm ply which acts as the reinforcement joiner. Above and below the main spar are two conventional 6mm square spruce spars which together with the full depth ply spar, run full length to the tips of both wing sections. 2.5mm balsa sheet spans the centre section with capping strips topping the majority of the wing ribs. It is traditional construction given a modern twist.

On the standard wing center line there exists a centrally placed 3mm rib. To keep that rib in one piece to act as a pattern for my re-construction, I cut down either side of the rib in order to preserve it as a template. That done, all I had to do was cut two new and identical ribs plus one that had and extra 2.5mm of height added to wing sheet level. The three new ribs were laminated together and that gave a glue land for new sheeting to be added either side of the center line. Dihedralled wing joiners were constructed for all three spars with the LE and TE spars having long, taper scarf joints machined on their exposed faces with a similar detail being machined onto the new dihedralled wing joiner reinforcer at the LE and TE. A replacement planted on balsa leading edge was glued to the front spar and sanded to profile. Wing dowels were re-located as the wing orientation is turned up side down (or downside up) which ever way you might wish to see it! Re-building the wing took just a day and a half and although I had to cut back covering in order to chop into the wing, some of this has now been replaced with matching Hobby King white and black covering with the Oracover bright day-glow orange also requiring replacement in various areas. Inevitably you can see where I have replaced covering sections but the end result is probably a 95% good job. I could have completely recovered the wing but that measure seemed rather extravagant. You have to examine closely to see where I have cut and shut this wing back together. The wing weight gain after reconstruction was just two and a half ounces.

The fin and rudder required triangular additions once the fuselage had been inverted. The tail plane is mounted exactly as for the high winger but obviously the fin and rudder had to mount at 180 degrees variance from the high wing model. Small dorsal fins have been added in front of the fin and below the fuselage. A modified Du-bro tail wheel assembly was required in order for the tail wheel assembly to mount correctly.

Inverted, the flat profile of the Ultra Stick looked very poverty stricken and uninteresting. It also visually looked "unfinished" and the presented top decking looked like it had been penned by the man who designed the railway sleeper. To counter that effect, a simple shallow, light weight "whale back" structure has now been constructed on what is now the top of the fuselage. This tapers in a straight line from zero at the front firewall to a height of 18mm approximately 30% back from the wing LE line and then again tapers down to about 6mm at the rudder stock. The effect is of a long, gentle curve of an elongated aerofoil which adds interest and character to an otherwise bland expanse of fuselage top deck. To pep things up further, I plundered Jim Feldmanns model for his cockpit idea. Jim had a molded, clear plastic canopy made for his model which is somewhat reminiscent of a P.51. To save additional cost and effort, I cobbled up a light ply and balsa cockpit, sanding to profile and covering with white Hobby King film and some silver film to hint at a glazed area. This cockpit represents an option or two. Once the model has been test flown without the canopy, it can then be added if desired and the model reevaluated to ensure flying characteristics haven`t been unduly eroded. Fitting only requires a bit of double sided tape and the gap disguised with a few strips of HK covering material.

The motor fitted is a brand new, unmarked and as yet un-run ASP.91 sourced at a bargain price from eBay. It is side winder fitted with the exhaust exiting just inboard of the starboard landing gear leg. It looks a neat and tidy installation and one that is rather prettier than an inverted install. My 1.08 version has the inverted set up and frankly, it is downright ugly as well as being more challenging at start up time. I changed the standard 8oz fuel tank for a Du-bro DB412 12oz tank in view of the large engine fitted and its fuel thirst requirement. The tank just squeezes through the bulkhead aperture forward of the wing. I soon realised that an access hatch would be impractical given that bottom access would be needed and that any chance of removal via that hatch would be impossible due to the new mounting location for the landing gear. Jim Feldmann also came to a similar conclusion as myself and he too also decided to fit the tank into the model via the wing leading edge bulkhead, dealing with any tank maintenance or cleaning when and if an issue ever arose. I don`t like sealing a tank in place but in this case, like Jim, I had little choice.

The model weighs in at 8.3Lbs/3.7Kg and is about a pound heavier than the very light weight electric version. The heavier .91 motor allows rudder and elevator servos to be tail mounted. All servos in this model are metal geared and as a result a pack of eight weigh just over a pound. Seven are fitted in this model. A 2600NiMh 6v Rx and servo battery pack is positioned on the main internal chassis plate just forward of the rear wing sheer bolts. Moving that battery for or aft is easily accomplished and has a useful weight shift which allows the C of G to be altered with little fuss.The weight and balance schedule now being what it is implies that the model is of a similar weight to one of Ali Macs prototypes. On that example, Ali fitted a beautiful if somewhat heavy Saito 19R3 radial engine and countered the weight with rudder and elevator servos placed at the tail plane leading edge. That model flyies wonderfully even at that weight so hopefully mine will do likewise.

With a reverse colour scheme now applied and with a standard high wing US along side, I find myself doing a double take each time I see two fully rigged models in the workshop. You think, "Eh, err, which one is the right way up"?! I still haven`t adjust to that visual impact yet. I wonder what others will make of it?

As always please guys, comments good or bad appreciated.

Mike

 

 

 

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In mid April 2019, I took the Ultra Stick theme further. I began construction of a high wing, twin engine version.

The project has been interesting with development occurring around a loose plan based on Ali Machinchys` Hanger 9 model. My twin is completely scratch built with the exception of an original Hanger 9 landing gear.

Two fuselages were constructed in the first week. As I was to dimension and cut one set of fuselage parts, it seemed sensible to make an additional spare for future use. It can either be used as a replacement item in the event of irreparable breakage of one of my other Ultra Sticks, or can be used for another Ultra Stick build project.

The twin uses a standard section wing rib taken from an original wing when I built the low wing version. Each wing rib was cut by hand from 3mm balsa rather than hard to work plywood. Each wing rib took me about eight minutes using the original rib as a template and cutting with a sharp scalpel blade. As a batch, the collection of ribs were dimension checked to ensure uniformity prior to inclusion in the wing build. A standard wing has 17 ribs. My twin version has had the wing stretched by 180mm ie 90mm/one extra panel on each wing half and uses a total of 25 wing ribs together with a slightly thickened 3mm x approximately 1700mm long. ply main spar. The spar has a vertical depth of 31mm . All ribs and spar components notch together to form a strong, accurate and warp free structure. Notch cutting in front and main spars is fiddly and time consuming but it is worth the effort.

A plated dove tail joint joins the two wing spar components together with the joint being off centre of the mid point of the wing. The extra ribs replace lost wing area as a result of the twin version employing two 90mm wide engine nacelles. Essentially, the nacelles are two front sections of a standard Ultra Stick fuselage. The sides extend up into the wing and the tops are shaped as a standard wing rib. In other words, the nacelles form part of the wing structure rather than just being glued to the bottom of the wing. Ailerons are also stretched in length but flaps remain at standard size. The construction was fairly complex and time consuming and took me a good three weeks of concerted effort. Total build time has been about one month in total. A standard scratch built Ultra Stick by comparison usually takes me a just a couple of weeks.

The fin and tail feathers have also been stretched by a proportional amount to match the new proportions of the twin wing.

The model is now fitted with two OS Max 46SF two stroke glow motors. Sadly, they do not contra-rotate. One very low time motor was sourced in the UK, the other is brand new and unused but I had to source from the USA to find a good unit. The two motors then, probably cost me about £85 for the pair. One will be known as "Essex", the other as "Miami"!

The wing stretch and weight of two motors has increased the final all up dry weight to 10.8Lb. That is about 5Kg. The fuselage only houses two metal gear servos for elevator and rudder together with a Futaba FS617 RX and a five cell, 2600NiMh battery. Cof G was easily obtained even with elevator and rudder metal geared servos tail mounted. For interest, eight metal geared standard servos weigh just over one pound. They are not light weight objects. Each motor with prop and silencer weighs just over a pound. The wing is extremely nose heavy with motors fitted even though the four MG aileron and flap servos are mounted aft of the CofG in the wing. The Cof G was easily set at a slightly forward position by placing the 2600 NiMh power pack right up against the front bulk head. ie the bulkhead to which the motor would normally be bolted. The nacelles also house two eight ounch Du-bro tanks and two mini servos for throttle control. Standard silencers are fitted. This model will obviously require noise testing.

Overall, this model weighs about two pounds more than a standard Ultra Stick. Ali Mac built one of his prototype models with a Saito R3 radial spark ignition motor. That motor weighs about the same as my two OS motors. As a consequence of the heavy weight, Ali also mounted the rudder and elevator servos in the tail. I surmise my twin version probably weighs around the same as Alis` Saito version....hence the use of us both using the tail end servos to achieve a reasonable CofG.

A nose cone is nylon sheer bolted to the centre fuselage. In these images, the cone appears rather long and may well get cut back in length. It is easier to cut a lump off rather than to retro fit additions. Getting the length looking right has been a challenge. I`ll get it up to the field and take others opinion on the matter. Then I can get the saw out again and hack a lump off!

Members pointed me towards James as the test pilot. When asked, James responded well to the suggestion. So it now remains for me to set the model up and ensure engine reliability. Advice suggests I should fit a gyro on the rudder to assist in the event of an engine failure. That seems to be a good idea!

Anyway, here are the images of the build and the finished model. Comments, as always, appreciated. Ignore the images of the tri-motor on No 3 fuselage. That just happened to be a fuselage I had to hand when I trial fitted the wing for the first time! A tri-motor...well that might be an interesting future project......

How many Ultra Sticks in the hanger now? Five and a half smaller versions and one complete scratch built 80" monster.....

What next on the Ultra Stick theme....perhaps a canard, a bi-plane or even a tri-plane. Watch this thread!

Mike K

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