Dolphin (oz1333)


Dolphin (oz1333) by Albert E Hatfull 1952 - plan thumbnail

About this Plan

Dolphin. Free flight towline glider from KK. This is a zip file of 2 pdfs: plan and printwood.

Update 20/04/2020: Unpacked this zipfile into 2 separate pdf files, the plan and the printwood.

Update 23/04/2020: Added kit instructions, thanks to NicholasTucker.

Quote: "Read these instructions through and study the plan before starting construction.

Two 'Side frames' are required for the fuselage. Pin the upper and lower longerons in position over the plan, place pins on either side of the stripwood, not through it. Pin the two short lengths which occur directly below the tail position in place, cement the joints. Pin piece 'A' in position, then cut to length and cement all the uprights between the longerons. Study the perspective sketch to check how the first 'side frame' should be made.

When the cement has hardened on this first side frame, build a second side directly over it using the same retaining pins where possible. While the second is drying, construct Former B as shown from 1/4 x 3/32.

Remove both side frames from the plan and carefully separate them. Remove Former B from plan and clear away any surplus cement. Apply cement to the inside rear end of each side frame - then join together. Before the cement dries on the previous joint, cement Former B in position where indicated on the plan, place an elastic band round the fuselage at former B to hold the sides into the corner notches.

When set, refer to the Top View and cut the cross braces to the correct lengths, and cement in place. Add the piece of 1/16 sheet at the rear which carries the sub fin. From the spare wood on wing rib printed sheet, cut two pieces to fit into the first bay at the nose then cement in place.

Mark the positions of the tow hooks in pencil on piece K, bend up the tow hooks from paper clips as shown then press the spike ends into 'K', cement and bind with thread. Apply cement to the notches in K then pass through the nose and press into place centrally in the fuselage, see Top View.

Roughly carve the nose block to the shape shown on the plan then lightly cement to the fuselage nose and finish with fine sandpaper. Remove the nose block and hollow out the back to receive the lead balance weight. The nose block complete with lead should weigh exactly one ounce. Make a cement skin over the lead to retain in place then cement the nose block on the fuselage and again fine sandpaper..."

Supplementary file notes



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Dolphin (oz1333) by Albert E Hatfull 1952 - model pic


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User comments

More pics. Another nice small glider [see more pics 003, 004] and a good one again build from the plan dowload. Keil Kraft Dolphin glider.
Joost - 12/08/2014
Hi. Your website is amazing. I build a Keil Kraft Dolphin [more pics 005]. See the build log in this link from Chile: Test flight Thxs
DavidVera - 04/04/2016
Was home for a week so I got some flying done and took photos of my three latest projects built with Outerzone plans. This is Keil Kraft's Dolphin at finishing stage, static and flying. I covered the Dolphin in pink tissue, a tribute to breast cancer and aids awareness here in South Africa [more pics 006-013].
AndyCoutts - 16/08/2016
Between 1955 and about 1958, I built several Dolphins. My chief memory of them is that, unlike many small towline gliders of the period, they towed straight - no weaving, no veering off to one side or the other. Note to builders: for the wing mainspars, choose the toughest balsa you can find - or preferably, for the centre panel at least, use spruce!
JohnP - 04/02/2018
I built a Dolphin glider back when I was 14 years old in 1955. Third flight off a 200 in button thread tow-line, it caught a thermal, (Of course, no D/T!) and I never saw it again.
Brian Templeton - 18/05/2019
There is no space for the dihedral brace on the ribs where the wing tips join the main wing.
Alan - 20/04/2020
Yes. I think KK expected you to build up all 3 wing panels, then as the final step, notch out the 4 end ribs (by eye) to allow fitting the 2 braces. Maybe the instructions are more helpful.
SteveWMD - 20/04/2020
You are 'right on the money', Steve. It was usually done like that in those days, carefully cutting the slots with either a thin file or a hacksaw blade after gluing the tips and centre section together.
I would use two dihedral braces per panel though, not one as shown. One for the bottom spar and another for the top one.
Arn - 20/04/2020
Yes, I quote the instruction leaflet: "When dry (wing tips to centre section) enlarge the slots immediately behind the top spar at the dihedral joint positions and cement the dihedral braces in position alongside the top spar".
I will scan the leaflet and post it to Mary
Nicholas Tucker - 21/04/2020
Dear Mary, Steve, hope you are doing well in these difficult times. We are trying to get the best of the forced stay at home; relax, reading, and trying to prepare for a way of life after the emergency is over - if possible- less stressful than before. And small gardening and, oh, yes, building airplanes.
Me and Laura had a good time buiding - one stick at the time- the little Dolphin (oz1333).
This is an RC conversion and I obtained it by adding a little movable surface to the h-stab, and splitting the v-stab in two. I have also reduced the angle between wing and h-stab to get a less 'nose up' attitude than required for free-flight, but I'm note sure it is a good idea. We don't know when we'll be able to fly it, but as for now we're happy of its outcome as static display!
Hope you may like the pictures I'm attaching of the tiny glider amongst Laura's beloved plants [pics 015-018]. We're very lucky to have this little home garden to pass time in during the lockdown; the gazebo, btw, has been handmade in England.
All the best and thanks
Raffaello and Laura - 07/05/2020
I built a Dolphin for lightweight elec rc. The little outrunner is on a pylon over the canopy, and that works well (needs a little upthrust). With that and the little 2s battery (300mah I think) there was no need for noseweight. I'll see if i can find a picture. I added gussets to the wing ribs at the trailing edge, and a hatch under the nose for the battery.
Jim - 20/08/2022
Hello, here are two pics of my elec Dolphin [pics 019, 020]. My version is unusual by having an electric motor on a pylon out of the way of the ground (!). Finish is good old tissue, and Ezedope as an experiment - which worked really well. Cheers
Jim Primrose - 27/08/2022
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