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Old Jan 23, 2010, 10:40 AM
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Alacrity Build

As some people had got to know that i was building a new version of the Alacrity, I was asked to do a build blog for this model.
The "Watts Up" build blog has generated a lot of interest in the art of actually building models, am going along with the blog, so as some of the ideas can be passed on, for others to use in later projects

As it is not widely known abroad, the bit below might be of interest:-

Alacrity Plus

Seems hard to believe that the Alacrity is now some 6/5 years old now. Alacrity Plus was built in 2008 to try to overcome the most serious handicap of the original, namely the ability to land accurately in competition that is vital to getting good scores.



The original, although only 2.6 metre span, would hold it’s own with much larger models, but steering with the flaps down was fraught to say the least, as any deviance from the line was very difficult to rectify using the V-tail controls only. Obviously full crow braking was the answer, but it was not easy to build into a model like this.



“Nothing ventured, nothing gained” as they say. I decided to add a bit to the span of the model mainly due to the fact that it would be heavier due to the addition of the extra aileron servos in the wing. So I scaled up the plan by 11% so as the wing tips at the join with the centre panel became 230mm I then made the centre panel parallel to match, so as the wing would sit on the moulded fuselage in the correct place. The ailerons and flaps are hinged at 20% of the wing chord.



The tail plane was made 11% bigger as shown on the new plan, with the fuselage kept to the same length by virtue of not being able to do anything else!!!



Power was now a Kontronik Fun 480/27 with 5,2:1 gear box driving a 15” X 10” prop, all up weight with a 2250 mAh 3 cell LiPo is 1490 grams.



When I first test glided it I felt it was somewhat special, as the glide seemed to go on for ever. The crow worked a treat when sorted out, so much so that the model can be dived with the crow extended at about 70/80 degrees, without the speed building up and with full control. The other strange thing is that although I use the ailerons and rudders coupled, it thermal turns best just using rudder and elevator.



In 2008, it triumphed at the British Nationals, 200W/kg League & Bartlett’s League.


This is not a build project for the feint hearted as there is a lot of laminating spars,leading edges, which are not seen to much nowadays. These are made up around an MDF former from strip, glued together then left to set overnight to match the curvatures, of the plan views of the wing and tailplane.

Will post some more as they are done.
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Old Jan 23, 2010, 06:44 PM
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Thanks for the build thread!
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Old Jan 24, 2010, 05:24 AM
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Couple more pics of the build showing port wing inner panel & centre panels joined together. The straws shown in the wings are for the servo leads to pass through. (you have to remove the plugs to pass through the staws, then reconnect them)

The new version does not have the parrallel chord wing centre section, but returns to the original tapered planform. This will just about fit the fuselage.
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Old Jan 24, 2010, 12:11 PM
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Hmmm I have been looking around for something to build Brian, I was looking at an Oly III but I would prefer a more home grown option. Looking forward to see the progress
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Old Jan 25, 2010, 03:51 AM
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These pictures show the carbon fibre shear web slots being cut with a small jig that ensures they are all in the middle of the spar position on each rib. The slot is only 2/3rds down on the jig for the obvious reason it would fall in half
Slots are taken down to the bottom spar after jig removed.

Carbon sheet material .035mm thick is cut to depth & slotted in around tube joiner as shown, then another piece goes the other side of tube, to encase tube.

Last picture shows centre, where the carbon sheet overlaps one bay each side of centre.
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Old Jan 25, 2010, 04:02 AM
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Quote:
Originally Posted by jiberjaber View Post
Hmmm I have been looking around for something to build Brian, I was looking at an Oly III but I would prefer a more home grown option. Looking forward to see the progress
The Watts Up is easier to construct Jason, plus the pack makes it easier to put together
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Old Jan 25, 2010, 06:09 PM
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Yes - I just found the thread. I have a lot of thinking to do after destroying the Bingo at the weekend (RIP).... however looking on the bright side this does free up the motor for something.

Which was the RE floater I flew at CMFA that time, all red, so I assume that was the Altricity+?
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Old Jan 26, 2010, 04:05 AM
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Quote:
Originally Posted by jiberjaber View Post
Yes - I just found the thread. I have a lot of thinking to do after destroying the Bingo at the weekend (RIP).... however looking on the bright side this does free up the motor for something.

Which was the RE floater I flew at CMFA that time, all red, so I assume that was the Altricity+?
Not sure, Jason, could be either Alacrity or the Watts Up as so many people have flown it when passing the Tx round
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Old Jan 30, 2010, 06:36 AM
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Been a bit busy on other things this week, so the build has slowed somewhat
However have a few more pictures to illustrate the progress or lack of it, whatever

The webbing is made from sheet of vertical balsa made up from cut 3 or 4" sheet, glued together, to form a sheet of vertical grain the length of the semi span, then marked out to a taper to suit semispan, then cut to fit between ribs. This saves having to sand the taper on every bay.

Check it out on a dry run as shown then glue into place with, using Araldite standard, as this takes a long time to set, thus giving you time to glue everything into place, between spar, carbon web,tube etc.
This MUST be done on the jig as shown, due to the heavy weights used to keep wing true, as any warp or non flat suface WILL leave the wing as to what the surface trueness is.

Showing my crude balsa stripper that I use for cutting strip etc, Very difficult to get stripwood that is of the same type as balsa varies so much. Whith this method, all your strip can come from the same sheet of wood, that you choose for whatever purpose it is for.
It is made from a piece of hardwood block, with a piece of 1/4 ply glued to it, to leave a 1/4" step to act as guide along the said sheet of wood.
Drill & tap to take an M6 or 1/4" bolt. Place an double edge razor blade or mini plane blade onto the side piec leaving approx 1/16" or whatever depth you want o cut, then clamp in place with bolt,washer & spring washer.

The mini plane blades are best as they are thicker than razor blades, but the later are good on balsaup to 1/4" thick.
Run a cut down either side for best results.NOTE The masking tape wrapped round the exposed end of blade, to avoid injury, don't blame me you have been warned, Piece of hard sponge would be as good.
The picture showing the packing piece, is for wider strip say 1/4" packing giving 1/2" wide etc.
To cut less than 1/4" add spacer inbetween the blade and side guide.

The aileron/flap hinge strips are made up from a composite, of 2 1/64th ply & 1 carbon sheet .014" in between. Made into a sheet 4" pluss wide then cut to 1/4" strips as shown. These give a good hard/strong edge at the hinge point & they are webbed inbetween after fitting.
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Last edited by Essex BOF; Jan 30, 2010 at 10:16 AM.
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Old Feb 03, 2010, 06:44 AM
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Some more pics of Centre Section reinforcing & Wing Retainer Bolt Block in place
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Last edited by Essex BOF; Feb 09, 2010 at 04:37 AM.
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Old Feb 05, 2010, 05:05 PM
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In the latest QFI, there is a picture of the early version of the Alacrity, with the caption stating that the version shown had a wooden fuselage this is inncorrect, as all versions have used the same fuselage, moulded from kevlar with carbon reinforcement.
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Old Feb 08, 2010, 12:11 PM
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Some more pictures of the wing build. Bit slow due to having to deal with other problems in the model world.
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Old Feb 17, 2010, 12:04 PM
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Some more pictures of the flap & aileron buildup
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Old Feb 22, 2010, 05:12 AM
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Starting to get near the end of the worst part of contructing the aileron/flap bits.
Photos attached
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Old Feb 28, 2010, 07:49 AM
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Some more pictures showing LE sanded to template, gussets in corner, note fitted as a triangular piece then radiused off & sanded to profile.
Finished tip panel.
Any comments or input?
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