viggkri

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Hi

If anyone is interessted, i would make a smal tread on my build of the Retrojet, its going too be a short tread beacause its very fast too build.
Some info from Tony Nijhuis website:

The Retrojet 75 came about from a plethora of requests for TND to design a conventional high wing trainer specifically for a Turbine engine.

We were amazed at the number of modellers who were either owners of a turbine engine or were willing to buy one but were uneasy about install their ‘pride n joy into anything other than a familiar and conventional looking model. Even more amazing, we couldn’t find a conventional looking trainer kit anywhere else on the market! TND have now put that right with effectively the first conventional high wing trainer designed specifically for Turbines.

It gives superb reassurance and a wonderful stable platform to either test your new turbine or be that elusive turbine model ‘hack ‘ you always wanted. The engine range is diverse and the model will take anything from a Wren 54 right up to the 80 size of turbine. The prototype was designed around the new Wren 75 Jubilee, and has proved an excellent choice, in terms of value, reliability and ease of starting”.

The plans are supplied on 2 large sheets of quality extended AO sizes paper and the VAC set includes a white HIPS nose cone. The CNC pack is very complete. All the pre cut parts to build the complete fuselage, tailplane and wing have been included.
The additional wood pack is main wing sheeting and spar material, all supplied in 48” length so no splicing to make long stock is required for this model.

Although this is a traditional builders model with a built up fuselage, wing and sheet tail and fin surfaces, the plan is very dependant on the CNC pack being used (almost kit quality rather than plan pack). All the information is available on the plan to scratch build, however, some builders may wish to use their experience is substitute materials to assist in their traditional build. As with all of our designs, you can download from this web site, a series of construction photos of the prototype build, which will be invaluable to those novice builders out there.


I fly Boomerang Elan from my "local" airport, 2000 meters of solid ground, the club field however is smal, gras and bumpy, so i think the Retrojet would be perfect.

Viggo
Norway

jescardin

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First to follow your building, Viggo.


Best Regards from Spain.

Jesus Cardin

petera38

Hi Viggo,

We´ll be following your thread here from Sweden as well, with interest!

/Pete
Sweden

viggkri

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I have started, the quality of the cnc "kit" is very good, over all the balsaquality is also great.
I like too use carpentersglue or epoxy with lite-ply, so most of the time is spendt waiting for the glue too set.

Viggo

jescardin

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Just a suggestion from a modeler who started building models 40 years ago ranging from free flight, control line and RC: if you do not like cyano for any reason, you may use synthetic (solvent based) glue giving a first coat for the wood to absorb and a second to form the union.

This technique is far more quick that white glue even if you use aliphatic type.

For a building like that I should use the synthetic glue for large parts like doublers, wood cyano for small joints like ribs and intermediate formers and, of course, epoxy for gear, wing and turbine formers and as well as for wing joiners/tubes.

These are the glue types I currently use for classic building and it is just a suggestion so you do not need to wait too much for white glue to set.


Best Regards,


Jesus Cardin

viggkri

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Jesus, thanks for the tips on glues, i guess its just an old habbit, and i do like the red Titebond, when i work at all parts of the plane at the same time, it goes forward.
I am using the Jet-Munt VT80 for power, slipps right in.

Some more pictures:

Viggo

viggkri

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Some more progress, basic structure of wing is finished, undercarrige is trial fitted, painted the innside of the fuselage.Viggo

viggkri

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Getting Close too covering.

Robrow

Nice trainer, looks like a copy of my conventional turbine trainer from years ago.

Rob.

alasdair

Very similar indeed Robrow.
Except yours has a tiny bit of sweepback, which helps. Did yours have the fuel tank overlapping/above the engine too?

In mine I put them in line astern (which make the modellonger and sleeker),and I used even more sweepback than you.

alasdair

You are certainly getting on with the build !! Is this your summer vacation?

Any more photos of the aileron/flap servo installation?

viggkri

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No vacation yet, been building 3-4 hours in the evening, one week since i started, total of 25 hours, the retrojet is now covered in plastic. Going away for the weekend, but a few days next week for innstalling hardware and then its ready for Maiden.Under the wing-skin there are some lite ply too suport the servoes.Viggo

Jannica

Hello!
I´m planning to start building this aircraft. I have the plan and the CNC-kit laid out on my building board. But I have some concerns about the build. I understand that this construction is prone to end up terrible tail heavy. In an article in June/July 2013 of RCJI, Dave Swarbrick says that he had to put 24oz / 680g of lead in the nose to maintain a correct C of G. Have you guys noticed this problem? If so, how do you intend to handle it? Personally I don´t fancy the idea of flying around with that much lead in the nose.
I have some thoughts about maybe make the nose a little longer or mowing the engine and the corresponding bulkhead a little forward or maybe both. But I haven’t made up my mind yet. What do you think?

Jannica
Sweden

viggkri

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I would do the longer nose, easiest fix, i have all servos under the wing and not in the tail, i belive i going too need 4-500 grams of leed.Viggo

viggkri

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Almost done, missing some pushrods on the wing and balancing ( i am afraid i am going too need a fair bit of leed ).Viggo

Jannica

Looks real nice! How far aft have you stretched the metal sheeting over the exhaust? I have not decided yet how to go ahead with my building. To nice days for flying just now so building can wait.

viggkri

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Shows better in this Picture.Viggo

viggkri

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Went too fly my Boomerang today, did the first start of the vt-80 and some taxing, soon ready for Maiden.Viggo

Jannica

I can see that you mowed the turbine a little bit more forward than according to the plan. Funny that you also have a Boomerang Elan. I am also interested in the Elan and I have it as an alternative to the Retro. I would very much like to know your opinion about how they compare when you have done the maiden on the Retro. Very fast and nice job on the Retro!

viggkri

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My plan is to use the Retro on some less than Perfect runways, i will also bring it when i go on vacation just too have a easy to operate jet on vacation.

I needed 900 grams too bring the CG in too the forward mark ( 90 mm from leading edge ), i hope too remove 3-400 grams after testflight, if i cant do that, i will rebuild the nose.

The Elan is a winner, the only reason too build the Retro is that the Club gras-Field is not for the smal Wheels of the Elan.

Ready for Maiden when the weather is ok, will Return With a flight report, and hopefully a smal video.

alasdair

What a lovely big stretch of perfect runway you have. I am SO jealous. Most of my jets wait months for a chance to fly off such a runway. The only ones I fly from the club's grass strip are my O/D JayTee and my Falcon 120 (with fixed gear).

900g is an AWFUL lot of lead to carry!!!
You need a longer nose, and a lighter tail.
I once replaced the 9mm sheet balsa tailplane from a kit with a foam/veneer alternative that weighed HALF as much. Looked better too with a proper airfoil.

Boomerang1

Good to see some jets using conventional model aircraft building techniques & materials. [8D]

When I was trying to get my head around turbine jets a friend reassured me they were just
normal models with a different engine. I'm a builder as well as a flyer so I admire a model
someone's built rather than the glossy machine that the owner has merely screwed the radio,
engine & other bits into.

A jet flyer asked me what my scratch built model was made from. When I told him trees I
just got the blank look.

Love the Jay Tee Alasdair, quite the versatile go-to jet.

John.

alasdair

Thanks, Boomerang1.

I get a bigger thrill out of flying a model that I've hand built than an ARF.

Bigger still by far when I've designed it too, and it flies great.

There are quite a few wooden plan-built ot kit-built sport jets now. As well as the Jetmach that viggkri has built there is the large version and low wing version, and Tony Hijhuis's model, and - well a few others I can't name offhand.
One of these days I'll get my JayTee plan drawn out properly and then there will be another.

Moulded composite contruction is very suitable for sleek curvy scale jets, but many unique scale jets have been build using sheet balsa as well. Dave Johnson's enormous 20 ft span Vulcan, or Steve Rickett's DH Comet and Gloster Whittle, and the VC10spring to mind.

Boomerang1

I hope so, I've just suggested a guy on another thread chase you up for details! [X(]


He's after a hassle free jet as well.


Yes, me too, my OD, the one built from trees!


- John.

viggkri

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Today i Maiden the retrojet, just a few clicks of trim and it flew hand off, little bit windy, but it flew very steady, trainer indeed. Video http://www.youtube.com/watch?v=av3idOuACHQ Viggo