Model making And wood work.

[ArtworksIII]

I like the fabrication involved with model making. Once the drawings are scaled it's just making parts and assembly. The model below is 4 hours from templates to what you see. One model can be made by 5pm each day and shipped the next morning. Very proud of that. I follow many of the original process to make models set down it 1942. But over time a modeler adapts his methods to suit.

[Richard in Smithville]

Very cool indeed.

[ArtworksIII]

Very cool indeed.

Any questions? Or we could talk about routers and making window trim.

[ArtworksIII]

Back to our roots

At this point there is interest at the retail level for well made kits with clean concise precision and possibly a website for each model to augment the kits templates and instructions. While the model making is time consuming the time involved is well worth the effort for the display model at the end.

[ArtworksIII]

The NOTAR is an old helicopter as I've found reference photos dating back to 2002 and earlier. The templates give you an idea of where the model comes from. The doors and panel lines an such are on the same level on both sides. The landing gear is cut cleaned and brazed for strength. Fairings are made from card stock.

[Stytooner]

Wow. Excellent work. No tail rotor? Is it a jet motor or exhaust that provides the stabilizing pressure?

[ArtworksIII]

Stytooner It uses a multi finned fan that blows out through the very end of the tail boom a lot of pressure. I can get to carving once it's 8 seat variant is built shown here. All that's needed is a little finesse and the carve should work out. But I have gone a little far and scrapped a fuselages. The Eagle graphic will be added as well with a lay up template. The landing gear fairings are test fitted and cut to fit. The graphic is added next as once the carves begin placement onto the model is harder. This graphic is really neat for it's age...

[mpc]

The NOTAR helicopters from McDonnel-Douglas / Hughes (MDC aquired Hughes during the NOTAR development years) date from around the mid-80s to early 1990s. Slots on one side of the tail boom have air blown through them, downwards, from the internal fan. The slots look like almost-closed venetian blinds. That airflow combines with the major downward airflow from the main rotor making that downward flow actually curve under the boom and become a more horizontal flow. Turning that much airflow generates a corresponding force - after all, it's changing the momentum of the air molecules of that airflow. That lateral force (aka side force) is what counterbalances the main rotor torque. The neat thing is that it is a direct function of the main rotor airflow so as pilot changes power or blade angles the reaction torque from the NOTAR slots changes too. A separate steerable vent at the very tip of the boom blasts air to actually yaw the helicopter per pilot commands.

Ever hold a ping-pong ball in a stream of air from a air compressor sprayer or from a shop-vac exhaust port? Similar idea - the moving column of air deflecting around an round/cylindrical object, relative to the non-moving air next to it, creates a force that can trap that object (the ball).

NOTAR has a few things going for it:
1: the aft rotor of most helicopters has to turn at a very high RPM to make enough force given its small diameter... so the rotor tips are moving at very high speeds - often close to Mach 1. Ergo lots of screaming noise. (by the way, the harsh "chop-chop-chop" sounds made by some helicopters is a small sonic boom from the advancing rotor blade tip velocity combined with the helicopter's forward velocity)

2: that tail rotor is quite vulnerable - and quite deadly too. The main rotor is up pretty high so it's unlikely to strike people walking to/from the helicopter... the tail rotor though can easily strike folks not paying attention. And, since the tail rotor is out of the pilot's view, it's easy for the pilot to misjudge where that rotor is relative to trees or buildings when flying low. The tail rotor & fuselage boom are longer than the main rotor blades so the tail rotor tends to be the first thing to whack stuff when maneuvering in tight spaces, especially when trying to turn. Kinda like the back end of a bus or RV swinging into things while turning.

Talking to some MD-520N helicopter pilots at a local airshow they did say the NOTAR helicopters can be harder to control in gusty winds compared to conventional helicopters. Anything that disturbs continuous/steady airflow over the boom & slots is going to alter the side force resulting in unsteady balance of the main rotor torque.

This Wikipedia article has some simple diagrams showing the NOTAR concept: Wikipedia discussion of NOTAR
MD Helicopters has its own description page at MD Helicopters NOTAR Technology (R)

I followed the MD-520N and similar MDC helicopters for a few years; they were being designed early in my career at MDC - at a totally different division. MD Helicopters was separate from the commercial aircraft section where I worked... but I was asked to help with Aerodynamic design stuff for the horizontal and vertical stabilizers at the end of the boom.

mpc

[atgcpaul]

[ATTACH]20162[/ATTACH]

Please tell me the orange chopper is a computer render.

I followed the MD-520N and similar MDC helicopters for a few years; they were being designed early in my career at MDC - at a totally different division. MD Helicopters was separate from the commercial aircraft section where I worked... but I was asked to help with Aerodynamic design stuff for the horizontal and vertical stabilizers at the end of the boom.

mpc

That was a very interesting read. Thanks for sharing.

[ArtworksIII]

Please tell me the orange chopper is a computer render.



That was a very interesting read. Thanks for sharing.

Model makers seldom know much about Specs engines power curves rather shape and asthetics.. And yes the model is based on the same line drawings as the above Animation.

Wow MPC you designed the end plates for NOTAR helicopters?

[mpc]

Wow MPC you designed the end plates for NOTAR helicopters?

That's way more than what I did. The folks doing the Aerodynamic design had a few questions and borrowed some of the Aero estimating tools I'd developed. Through a series of phone calls/teleconferences we discussed trade-offs and "if you do that, then you might have issues with ..." or "when you alter taper ratio to fix aaaa you trade off bbbb" type of things.

mpc

[ArtworksIII]

That's way more than what I did. The folks doing the Aerodynamic design had a few questions and borrowed some of the Aero estimating tools I'd developed. Through a series of phone calls/teleconferences we discussed trade-offs and "if you do that, then you might have issues with ..." or "when you alter taper ratio to fix aaaa you trade off bbbb" type of things.

mpc

Well I guess you had some Data worth investigating MPC

[ArtworksIII]

From a pure static display modelers view the diversion from planning strips of wood to fix your 100 year old hardwood floor to cutting 4x8 sheets of plywood a day out from the typical project is welcome. Modeling projects can take acouple weekends or a few days. Some of my weather vanes only took a few hours. No matter how rudimentary the project seems most true wood workers see the lite hearted nature of model making.

[ArtworksIII]

Some of the models shown in this thread lent themselves to playability and others like this one not so much. I don't get a lot of time to work on my projects much during the summer months but winter and weekends always find me at my desk.

[ArtworksIII]

On the other hand there are projects that the playability is 100% since the over all model can be fixed time and again. This model can be built up in a matter of hours. Again the one on the bench is is not good for play as it is over a yard long. The model with the large nose is a great toy. Notice the line drawings are not of the same plane. They do sell well.