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New Parasol Design, think will call 'Kestrel'


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Its been a while for various reasons but a couple of designs in progress, always tricky working on more than one project as one always seems to take over and so was the case here but i just fancied cracking on with this as it is not too big and I had a very clear view on the construction and design so it has gone together pretty quickly.

 

 Kestrel Design.pdf

 

56inch span parasol design on traditional construction that will be powered by an ASP52 4stroke or easily converted to electric power.

 

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Build is now quite advanced but i will start uploading from the begining shortly

Lindsay

Edited by Lindsay Todd
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for a change I stated with the tail surfaces, the fin and rudder have a 6mm balsa strip tail post and leading edge and then 2mm sheet center core and then 2mm sheet strips both sides. I added some 0.5mm ply to the base of the rudder to fix the control horn.

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The tail plane is from 6mm sheet cut into strips and sections and the elevator as per the fin and rudder joined with a 2mm piano wire U shape again with ply plates for strength and fixing of he control horn.

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Nest the fuselage, well i got a set of parts laser cut by Slec so that made things easier and the cooling slots in the front sides of the fuselage were an easy addition as a result. to be honest they are largely cosmetic but then why not. The fuz sides came in two halves so first job was to simply glue together he front section and then make up the rear outer frames of the rear latice structure and make up two complete sides. NB diagonal bracing not added to rear fuselage at this stage.

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Next job was to add the lower ply doubler and then the 6mm square longerons that run down the fuselage inside faces and also help key the positions of the formers made from 3mm lite ply into position. I fitted the front formers back to the rear of the cockpit and then joined the fuselage sides together and added the cockpit floor. This helps keep everything square before pulling the rear fuselage sides together and adding the rear formers.

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Withe the rear fuselage pulled together using 6 mm balsa inserts top and bottom the rear top stringers were added and the rear diagonal bracing

 

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At the front the position for the engine firwwall was measure marked and then glued in place. NB the engine mount was pre installed using captive nuts and bolts

 

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and finally for now a quick test fit of the engine

 

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that will do for now as glue has dried so time to crack on

 

more soon Lindsay

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following on, with engine mount set i could fit the front former which is the back plate for the nose really and the whilst that was drying i made up the wing strut fixing plates with M4 captive nuts that locate into sub former F3C and F4.

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Again whilst that was drying i made up the front hatch that gives access to the motor or battery compartment. This is made up from to sub formers, 6mm square balsa strips and then wrapped with 0.5mm ply with an overlap of 6mm so that i can scew fix later into hardwood blocks i will mount inside the fuselage. I used a couple of pieces of cereal packet card added each end to set the length so  i get a good fit but not to tight.

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i moisten the outside face of the ply and clamp it in place and allowed to dry to help induce the shape before gluing in place.

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a laminate of 6 + 3mm soft balsa is glued and shaped to the font F1 former to create the nose and the top hatch test fitted

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next job was to purchase and bend some 15x1mm aluminium strip, actually much easier than it might sound

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once bent and drilled the struts are bolted in place using thread lock and locking nuts as access to these will require surgery in the future so i don't want them to come loose. the 6mm stringers can then be added over the top.

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again i used 0.5mm ply to form the top of the fuselage which extends to half way across the cockpit area. I cut away to clear the struts and then glued in place squares of 0.mm ply to below the struts to fill the gap

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and a quick test to check it aligns with the front hatch

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A card template was made for the cockpit opening and was then trimmed away

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the rear part of the cockpit is made up of 3 further sections of 0.5ply

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more soon. Linds

 

Edited by Lindsay Todd
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next onto the wng centre section which will be bolted to the struts. Pretty simple construction with 6mm square spare and aluminium/phenolic tubes set into the wing ribs with ply doublers. 6mm strip leading edge and soft block to the trailing edge cut out. hardwood blocks with M4 captive nuts and then the entire assembly covered with 1.5mm balsa sheet.

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i used an incidence meter with the tail plane set at zero with a spirit level to give +1 degree as a notional starting point and will make any adjustments after first flights with washers to shim incidence or thrust line if required but should be pretty close from experience.

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next job of the day was to trim the top hatch for the motor. at the end of the day this is a sport model so access to glow plug and simple silencer clearance was the order of the day.

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Time to crack on and next job was to fit the 6mm undercarriage plate, this has a 3mm ply laminate on the inside not visible here and also triangular balsa reinforcing pieces around the inside edges.

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3mm balsa sheet was then added from the front of the undercarriage plate to the front of the engine mount former. forward of this will be a removable hatch so hardwood blocks were glued in place in preparation.

 

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since i was fitting screw fixing blocks i also added for the top hatch which are inset into the 6mm square longerons

 

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On a similar theme i added the fixing blocks to the underside servo access in the fuselage for a 3mm ply plate that will form the cover

 

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final job for the day was the 3mm aluminium undercarriage which was cut and bent to shape and then drilled for 4mm piano wire axels and screw fixings into the undercarriage fixing plate.

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The axle is a bent 4mm piano wire that is bent to shape and flexed into the aluminium form and then retained with a central saddle clamp and fixed with self tapping screws to the undercarriage plate

 

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more soon. Linds

 

 

 

 

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Time to align the fin and tail and make up the fairing blocks from laminates  of soft balsa. a temporary fit of fin and tail to mark center lines then having removed the fin and tail i added a couple of scrap pieces of 6mm on the lines and then glued laminates to the back of former F9, when dry planed and sanded to match the fuselage.

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i have used snakes for the rudder and elevator linkages which have been located and supported down the fuselage so time to do some covering to the open structure using and antique heat shrink fabric. this was applied giving a short overlap the the front fuselage of circa 1/2inch (12mm).

 

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the fin and tail where covered in the same and glued into place checking all was square

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and to finish off this area, the rudder and elevator were covered in the same, horns fitted and hinged with fuzzy mylar strips and thin cyno.

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The covering is pretty shear so shows up all the construction this can be both good and bad but also is a very good base for paint so i think this model will have a mixture.

 

 

 

 

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the forward fuselage and hatch has been covered with glass cloth and acrylic finishing resin from Deluxe Materials and is really nice to work with, no smell, fast drying, can be applied with a soft brush which can be cleaned with water. A few coats with sanding between is all that is required to get a really good surface for paint.IMG_6365.thumb.JPG.fb75706877baa7000b6428c27b844a76.JPG

I have overlapped the glass cloth by 12mm or so over the heat shrink fabric so we have no joints and everything is sealed.

 

Linds

t

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Bit more glass cloth done to the fuselage followed by trim and  sand and further coats of acrylic resin (not sure why this photo loaded upside down)

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then time to make the 3mm lite ply engine hatch and servo bay hatch on the underside including a test fit of the u/c

 

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Once i was happy with the finish coating i installed the rudder and elevator servos and connected to the rudder and elevator

 

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next job will be the outer wing panels. more soon Linds.

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ok so cracking on with the outer panels and starts with fixing 6mm spars (front being spruce as i has some spare but hard balsa wold have been fine) and then positioning ribs and gluing in place.

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next top spar and then the wing tubes were cut to length and slotted into place together with ply doubler's and glued in place followed by strips of 6mm balsa for leading edge and trailing edge to aileron cut out. I also added some 6mm ply blocks for the strut fixing and a couple of triangular sheet strengthening pieces between ribs and leading / trailing edges. 

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straight onto the 1.5mm sheet to the top surface starting with a 25mm wide strip aligned with the aileron cut out, then to the trailing edge between the two outer ribs each side, extended hen to the trailing edge of the front spar and then the front section to leading edge.

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extra 6mm balsa is added at the leading edge tip to aid shaping. Then time to add the top sheeting and the cap strips

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on the underside the cap strip needs to be off set and glued to the edge of the rib at the aileron position to allow fitment of the 1.5mm ply servo hatches

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wing tips are 3mm balsa profiles glued on centre line of the outer rib and the 6mm wedges glued top and bottom aligned with the spars and leading edge

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when dry this will be sanded to shape, then time to make the second panel.

 

more soon Linds

 

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Thanks Steven, yes i invested in getting the parts laser cut by Slec when buying the timber, makes life easier as i do all the design work on cad these days and the cost i think is quite reasonable compared to buying sheet stock and the time required to cut all the bits. It has been a bit of a retro update but i have caught up with progress now so updates may take a little longer but we have a local fly in on 20th June so hope to have the design ready for that. I find its good to have a target to aim for as it keeps the distractions at bay. Will hopefully look like this.

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Linds

 

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You know what Ron, until your question i had not realized, clearly I am a creature of habit but it should not cause any issues as the wing loading should be quite low and I do not envisage any serious tip stall issues short of dodgy piloting by yours truly but I do need to tweak the plan to show the same construction now I have done it. There are lots of claimed benefits for tip shape and profile but these are diminished by factors of scale so it is probably a case of visual appeal rather than aerodynamic performance on a model like this. Thanks for your input. Linds

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Time for an update and both outer panels have now been completed and aluminium tube cut to length so a first proper assembly check was required

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so far so good

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So pretty happy with that, just a general sand a few little fill bits but all good and square so the next job was to make up the wing struts and brackets. The struts will be 2mm wire with a loop bent one end for screw fixing and a 90 degree bend and clevice keeper at the other. 

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a couple of simple 1mm aluminium strip brackets are kinked and drilled to receive the 2mm wire and screw fixed to the undercarriage plate behind the main undercarriage

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simple loop and screw fixes at the other ends. next job will be to clad with 2mm balsa to add some shape, then onto the ailerons.

more soon. Linds

 

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just a bit of an update on progress starting with the struts witch have been clad with balsa strip to give some more dimension to them 

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once the glue had dried these were shaped and sanded to an aerofoil profile

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I will probably glass cloth these to add a bit more strength rather than using just heat shrink fabric

Next job was to make the ailerons which are basically two strips of 6mm to form the leading edge, a 1.5 sheet makes up the base which has a 3mm ply plate added and then 3mm balsa riblets on top

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once dry the leading edge is chamfered as these will be top hinged and sanded to match the wing profile

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next job is more covering and radio installation so not to far away now.

Linds

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Spent the last few days or at least a couple of hours in the evenings doing a little covering of the wings and hinging the ailerons using a top hinge techniques with the heat shrink fabric

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then cracked on installing the ailerons servos, hitec mini metal gear in this case side mounted onto hard wood blocks that are glued onto the ply plates with arm passing through a slot and short 2mm wire link to the ailerons

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a bit more paint work now required before final set and then off to the field.

Linds

 

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Well i nearly got this finished for my planned day (today) but with the wind howling through the trees it is a none flying day at least for new models anyway so with that in mind I can resume a more leisurely pace in adding some finishing touches. I though it worth posting a couple of pics though as the model now in a fully assembled condition and ready for flight if not in her final colours and markings.

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The forward fuselage has some paintwork but the wings still have some detailing required on this front. Note the silver centre section, you never have quite enough covering do you! I will get this to blend into the final design somehow although i actually think it looks ok.

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British racing green with a slight metalic hint adds some period charm i think. I need to work on getting the clearance hole around the needle valve better, you would think after all these years i could do that but a little detail plate over the top will disguise that guff!

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the details remaining are the tail wheel steering linkage, windscreen, pilot and more paint and graphics so just a couple of leisurely hours should see things complete and then just wait for a descent day for flying. Linds.

 

Edited by Lindsay Todd
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