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Glasair III, race number #42


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This thread is about a long time project from me. 2007 I started looking for information on the internet, a plan service (nice 3-view, but completely wrong fuselage shape from the top) and got a 3-view from the Glasair company. I also put a question for pictures on the aafo racing forum and got a nice response from one of the builders and Kevin Eldredge, the race pilot. Good forum, too, for air race fans:

http://www.aafo.com/hangartalk/forumdisplay.php?2-Air-Racin

Once again I made a small wooden model for my 1/72 collection.

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Building started in 2009. A bit too soon, since not all parts were designed completely. Which was the case for later troubles when building the plane. The other problem was time and that you loose energy for finishing a project when building lasts too long. My brother kept me going and told me to finish the Glasair over the years.

The Glasair was the first kit plane made from glassfibre mouldings and was always improved since 1979. It's quiet small with 7,09 m for the short wing. The III version has a retractable landing gear and a 6 cylinder Lycoming with 300 hp, which leads to 500 km/h. Due to high wing load the plane is only suitable for long airfields of around 3000 ft.
The Glasair is used as a racer at the National Races in Reno, USA. I did model pylon racing with race number 42 so it was clear to look for a original one with that number. #42 was sold years ago when Kevin Eldredge build and flew "Relentless", a Nemesis NXT. Today it still flies at Reno as #47 "Lucky Mojo". The fastest Glasair III managed to go faster than 400 miles per hour a few years ago!

Scale is 1/4, which was the reason for me to build the TK4 in the same scale (started later but finished earlier). Construction was once again based on a 3-view and photos, since no reliable material was available for the Glasair III.

wing span 178 cm (short wing, long wing would have been 206 cm)
length 167 cm
wing area 48 dm²
weight 5900 g
wing load 123 g/dm²
airfoil SD6060, modified to 12%
incidence +0.5°
washout 2°
down-/side thrust 0°/0°

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Edited By Timo Starkloff on 22/08/2017 22:01:54

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The model is just completed for flying but not finished. The canopy is not clear, the cowling fixed with tape, ...
I also switched to an electric motor last year, so the accumulator hatch is a bit provisional, too.

The motor is a Scorpion SII 4025-520 with a Jeti 120A controller and 6S5000mAh accumulator. The propeller is actually a 16x10 Graupner Sonic and will be changed for a 16x14 later. Current is at 70A on the ground and 62A in the air with th 16x10, the motor will work with up to 100A.

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I was quiet nervous between the two days from roll test to first flight. But flying the Glasair is easy and the first flights were flawless. Wing load is high, of course. Too tight turns lead to a wing drop and should be avoided, start and landing is longer than for other planes. But the Glasair is the smoothest plane I ever flew. The stability in the air is absolutely great. For landing you just have to adjust to the center of the airfield and control the descent rate with motor power, elevator stays straight and ailerons and rudder is not needed

I still have to make further tests with different flap settings for different weather conditions. The first flights were done without flap and I increased the angle always a bit on the next flights.

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  • 5 months later...

Another task for the winter is to improve the looks of my Glasair and the retracts. I had some problems on the last flights in summer and found out, that the clearance for the wheels is too tight.

Some parts like the accumulator hatch were just fixed by tape. The cowling got extra inlets and the six-cylinder-Lycoming a proper exhaust

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  • 3 weeks later...

The Glasair does fly nice. I have the ARTF version with a 26cc petrol and goes like stink! Surprisingly, the glide is quite good, although seems heavy, keeps on flying. Found that out when I took off and didn't remove the tank vent. after a few mins the engine stopped, but landed ok, even though was quite low.

Didn't know there was a retract type, although homebuilds seem to get many versions.

Glassair

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  • 2 months later...

Hi Paul, the III is the most developed version and has a retractable gear. I don’t think I want to try an engine off landing with mine. It will work, but with the high wing load there is only one chance to get it right. Just for comparison, what’s your fuselage width, wing area and weight? I heard from a friend that the Black Horse Glasair flies fine.

The clear canopy is still not finished, but yesterday I managed to make a short video. The first flights since last summer, so I was a bit anxious. Landing gear is doing fine now, but the spinner produced vibrations and was left away for flying.

**LINK**

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Hi Timo

I'm so pleased that I've found your thread, which I didn't see last year. Your construction shots are most instructive and inspirational, whilst the flying shots present the model superbly and the video definitely puts the icing on the cake. I can't believe that there are so few comments from other modellers.

I note that you built the ailerons and flaps integral with the wing structure before separating them for hinging, the slotted flap hinging being most impressive.

Your illustrated build has provided me with much food for thought regarding my own next scratch-built project which like yours will be a model of a side-by-side twin seater, will be about the same size with a huge cockpit canopy, and will benefit from being built as lightly as possible.

A very big thanks for sharing your skills with us all.

Kind regards

Gordon

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Hello Gordon,

thanks for your kind words. I also enjoy following other building threads and I'm learning through that, too. Internet is a wonderful thing for that kind of national and international exchange. And I especially like that forum here because many people actually build models and these are of normal sizes and weights.

The basic concept of the Glasair is from 2008/2009 and mostly follows the traditional way of model building. My De Havilland TK4 is a much improved version, many details are easier and quicker to build. But the Glasair is doing fine and flies well, so the concept works.

Regards, Timo

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Maybe it's of interest for some, the flight manual of the original Glasair III is available for download on the manufacturers homepage:

**LINK**

It's really interesting to read, with many useful hints also for model flying. In all parts of the manual are clear warnings about how to handel the Glasair. The P-51 Mustang is used for comparison of  flight dynamics and characteristics. For the first flights a flight field of 4000-5000ft length is recommended. A real high performance plane for experienced pilots!

Edited By Timo Starkloff on 26/05/2018 23:24:18

Edited By Timo Starkloff on 26/05/2018 23:25:09

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