Algebra build thread

All non-scale topis should go in here for discussion.
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Peter Balcombe
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Location: Clevedon, North Somerset, U.K.

Algebra build thread

Post by Peter Balcombe » 11 Nov 2017, 18:10

The original Algebra glider was designed by Sean Bannister many moons ago and Algebra variant kitted by Dick Edmonds under the EMP banner.
Although the original Sean Bannister model had a ply fuselage, later versions used polyester/glass mouldings made by John Hall, who also made fuselages for the Pat Teakle Sailplanes range.

Although these kits went out of production long ago, John Hall has offered to make the fuselages available again, so Cliff Evans is keen to offer an updated 'Algebra' range of short kits based on the original fuselage.
The most successful model in the range was the 100" or 2.5m Algebra, so I have taken on the task of designing a new built-up construction type wing with ailerons & flaps to enable camber control and crow braking instead of the previous inboard flap arrangement.

The new wing is attached using 6SWG rods as before and also contains an aluminium ballast tube to take 7/16" diameter ballast slugs.
Aileron and flap are operated by slim wing servos. The cruciform tailplane is mounted fairly high on the fin to avoid ground damage and is of the AMT type.

Although not a full build thread, the following should give an idea of progress so far as we catch up with what has been done in the last few weeks.

I started on the wing assembly to check out assembly of the new design after Cliff had laser cut the parts.
The basic structure goes together quickly as the ribs are slotted onto the full depth ply spar webbing, with the front ends tied together by a false LE and the rear ends slotting into the balsa TE spar.
A flap servo tray is also inserted at this point. (similar aileron servo mount is laid onto the underside of the top skin later)
Once the main spar have been glued in plus the joiner & ballast tubes, the false LE & TE spars are sanded flush with the ribs tops and the upper sheeting added.
Attachments
Wing structure_small.jpg
First wing structure
Wing root structure_small.jpg
Root structure
Sheeted wing_small.jpg
Sheeted wing

steve dowell
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Re: Algebra build thread

Post by steve dowell » 12 Nov 2017, 01:03

Looks nice Great model all back to the 1980s

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B Sharp
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Re: Algebra build thread

Post by B Sharp » 12 Nov 2017, 08:21

Remember to use the upside down camber on the tailplane Peter. Most Important !
Brian :)

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Peter Balcombe
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Location: Clevedon, North Somerset, U.K.

Re: Algebra build thread

Post by Peter Balcombe » 12 Nov 2017, 09:01

Thanks for the reminder Brian.
I had noted the 60/40% tailplane camber note on the original plan & will need to try to incorporate this when I profile the balsa blocks to section.

john greenfield
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Re: Algebra build thread

Post by john greenfield » 12 Nov 2017, 09:18

You guys may be interested to know that Sean Banister has come back into modeling and is a member of my local club. I am sure he will be keen to know of the regeneration and interest in one of his designs.

AEB
AEB = Aeronautical Energiser Bunny (with thanks to CW)

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Chris Jesshope
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Re: Algebra build thread

Post by Chris Jesshope » 12 Nov 2017, 09:30

Thanks for bringing back memories Peter.

I used to own the original original built up, square fuz, rudder elevator Algebra, then bought an Algebra Race 2.5m kit with the RG15 section. It was my first attempt at glassing wings. Not too successful in terms of quality of finish but it still flew very well. Here it is at the Hole of Horcum.
Attachments
DSC00145 (1).jpg
DSC00149 (1).jpg

Martin G
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Location: North Wiltshire

Re: Algebra build thread

Post by Martin G » 12 Nov 2017, 10:23

I'm following this thread with interest. I have an original fibreglass fuselage in the attic.
I bought a 3m aileron Algebra second hand in 1995. The wings didn't last long and I built a 100S set of wings for use in competitions. I think the model got through four sets of wings before retiring to the attic.
Hopefully a wing only short kit will be forthcoming.
Martin.

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Peter Balcombe
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Re: Algebra build thread

Post by Peter Balcombe » 12 Nov 2017, 11:39

Thanks guys.
Please note that the current wing design is for the less swept back version similar to the EMP kits, but probably easy enough to realign joiners & root rib to increase the wing sweep.

Meanwhile, once the top wing skin is in place the building tabs can be removed from each rib and servo boxes/cabling etc. done prior to preparing the wing underside for the bottom skin. I also fitted a hardwood block inside the root rib between the main spar and forward joiner tube to accept a MPX Unilock wing fastener later. The aileron servo mount is a laser cut ply shape which is simply glued to the upper wing skin. Servo is clipped into this and may be secured with a few dabs of hot glue.
A further addition was 1/8" balsa strips between each rib at the trailing edge spar. This increases the spar thickness to 1/4" to carry the control surfaces/hinging.
In order to preserve the correct wing washout when applying the lower skin, I laid the wing in a simple cradle made from four 1/4" upper surface templates as shown in the photos below.

Once the sheeting done, sand back sheeting at LE to the false LE before fitting the LE. As I had designed for a 3/8" total thickness, I fitted an 1/8" balsa strip plus a 1/4" hardwood strip to reduce weight, but any combinations of balsa/hardwood can be used to suit your taste/landing areas.

The balsa wing tip blocks are then added and sanded to the wing profile. The tip TE and control surfaces are made from 1.5" x 3/8" tapered stock balsa.

Note that although this build is for a 2.5m span wing, the intention is to be able to use alternative wings (certainly 3.2m) on the same fuselage joiners in due course.
Attachments
Wing beds_small.jpg
Wing beds
Wing underside_small.jpg
Sheeted wing underside plus tips & LE
Aileron servo box_small.jpg
Aileron servo box
Aileron servo_small.jpg
Aileron servo
Flap servo box_small.jpg
Flap servo box
Flap servo_small.jpg
Flap servo

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Cliff Evans
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Re: Algebra build thread

Post by Cliff Evans » 12 Nov 2017, 12:17

Would be great to get Sean's views.
john greenfield wrote:
12 Nov 2017, 09:18
You guys may be interested to know that Sean Banister has come back into modeling and is a member of my local club. I am sure he will be keen to know of the regeneration and interest in one of his designs.

AEB

roo Hawkins
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Re: Algebra build thread

Post by roo Hawkins » 12 Nov 2017, 14:34

john greenfield wrote:
12 Nov 2017, 09:18
You guys may be interested to know that Sean Banister has come back into modeling and is a member of my local club. I am sure he will be keen to know of the regeneration and interest in one of his designs.

AEB
that is interesting sean Banister has also joined my club also. ( ivinghoe soaring a )

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