Category Archives: Experimental

Propeller nose piece prototype

I did some experiments this evening with the new 3D printer. This will be used for making propellers but this evening I decided to try and make some propeller nose piece (hubs).

I was pretty impressed. I cooked up a couple of hob designs in a CAD program and then ran it through the machine. Now that it appears to be working nicely I will add some down thrust and some landing gear fastening system. Once that works I’ll see what I can do to minimize plastic use.

This material is PLA (Polylactic Acid). PLA is a biodegradable thermoplastic that has been derived from renewable resources such as corn starch and sugar canes. This makes PLA environmentally friendly and very safe to work with.

 

 

 

 

Adding an aileron to model plane

I was asked to clarify how to add an aileron to a Squirrel (or any stick and tissue model plane for that matter).

I use ordinary copy paper and cut out a rectangle or a tapered rectangle. Come think of it any shape will work as long as there is a long edge to attach to the wing.

20lb Copy paper is about right. I tried with tissue and it’s too light to keep it’s shape.

Scissors are best. In my example I actually used a hobby knife since I was in a cafeteria and I found my hobby knife before I found my scissors. 🙂

For a Squirrel I usually make the aileron about 3 inches long. I suppose 4 inches is good too. An inch wide is about right. In the example to the right I made it a little narrower than that.

If you have a glue stick you can put a thin layer along one of the long edges. I like a glue stick since you can probably easily remove the aileron if decide you don’t like it.

In the event you use white glue or craft glue be sure to use a toothpick or something to smear a thin layer along a long edge.

I used a bit much glue in the picture. But I was in a rush since I was about to do a flying session at a seniors residence.

You can then glue it to the trailing edge (back) of one of the wings. Any wing will work but I usually use the left. Most of my Squirrels turn right so I put it on the left and then bend it up a bit to bring the left wing down during flight.

Many people like having two ailerons. But I like just one. If it doesn’t work well enough I either make a bigger one or I make another one for the other wing.

Once you have an aileron (or two) on your airplane you can experiment bending them in different directions to affect the direction of flight.

If you have one I think it’s the easiest to start with.

But if you have two, there are a lot of options to try.

If you bend one up and one down, it will be twice as effective.

If you bend both down at the same time, then it is actually referred to as flaps or flap.  Flaps can reduce the speed of the airplane and is used for landing and takeoff for many airplanes.

If you bend both up it’s called spoilers. This is used for breaking and can be used just before landing as a way of bleeding of extra speed if the plane is travelling a little too fast.

For a Squirrel or any other simple stick and tissue model a single aileron can help get the airplane to go straight or in the right turn radius to suit your flying venue.

How an aileron works

An aileron on the left wing will raise the wing if it is bend downward (turning the plane right). It will drop the wing if you bend it up.

On the right wing it is the same except raising the wing will turn the plane left.

As a rule if you change the aileron setting of an airplane you need to change the pitch settings too. If you make the plane turn more then you need to make a pitch adjustment to raise the nose. If you make it turn less then the nose will raise so you need to make a pitch adjustment to drop the nose.

On a Squirrel the pitch is controlled by the wing position. To raise the nose move the wing forward. To drop the nose move it back.

Adjust aileron and pitch in small increments.

 

Superstar Squirrel

I received this awesome letter from Arun Prasad, Cessna Aircraft Company in Bangalore. It was entitled “Superstar Squirrel”.

Hi Darcy.

I am Arun Prasad from Bangalore, India. I work as a Manufacturing Engineer for Cessna Aircraft Company in Bangalore. Our company organised an Indoor free flight competition last week. We had 5 categories to compete in. Our team was called Silverwings. The 5 categories were

1. Longest Flight (Time Measured in Seconds)
2. Furthest Flight (Displacement measured in Meters)
3. Best overall Design as rated by judges
4. Most accurate flight. (The flight must land in circle of dia 1m when launched from 20 meters distance)
5. Most attractive Design as voted by audience.

As a engineer working in Cessna, I was smitten by Squirrel and I read the extremely good reviews and I got a clear picture of why Squirrel is the world`s most loved model plane. I decided to build Squirrel for the competition and I am very much proud to say that Squirrel was the superstar of the competition. There were 17 teams with more than 40 different airplanes and Squirrel was the numero uno at the competition. It won in 4 categories out of 5 categories. It came 1st place in longest duration with a flight time of 10.59 secs. It was 1st in the best overall design as rated by judges. It was most attractive design as rated by audience. It came 2nd in the most accurate flight (we missed it by 0.03meters) and it was 4th in the furthest flight. Squirrel just swept all the awards. It conquered many hearts. It was a pleasure to watch Squirrel. I posted some pics. Have a look at it.

I am sure Squirrel can do a flight better than 10.59 secs and It can go further. We used a 5 inch propeller (due to non availabilities of a 6in prop) and our balsa that we used, wasn’t good enough. It was too soft and was breaking everytime we launched. The only category Squirrel didn’t win was the furthest flight. It was basically taking left or right turn, where as it was supposed to do a straight flight to cover the distance. We had our competition in a gymnasium. So, we basically used a underpowered propeller and a undersized rubber band with too soft balsa wod. Still we managed to win over all the other model by a huge margin. It would be really grateful if you could send us the original squirrel with the right rubber band and right 6″ prop. We as aircraft engineers would love to have a original version of the squirrel. In Fact, I have modelled the Squirrel in CATIA V5 Environment (I’ll send you some screen shots) and we are trying to learn the aerodynamics of Squirrel and why it flies so well. I have sat with the aerodynamics team and we are trying to figure out some basic aerodynamics such as L/D ratio, Wing aspect ratio, Lift equations, etc etc.

But Darcy: You are one fine aircraft designer. I am really amazed the the Squirrel`s easy construction technique, and how well it flies. All credit to you. During the field test, I went to a nearby cricket ground (cricket is equivalent to American baseball). The moment I started to launch my Squirrel, I was surrounded by many kids and they all wanted to get a peek of how Squirrel flies. I could see how happy they were. Overall, Squirrel has impressed everyone around and its the new superstar. Along with Squirrel , I too got fame and name. But, you are the one who actually deserves these accolades.

Thanks
Arun Prasad
Cessna Aircraft Company
Bangalore, India

Web Site Report

I’d like to apologize to anybody who tried to visit this site and had difficulties loading the site.

There was a problem with our provider. I have resolved this problem by transferring the site to a new provider that has a much better reputation and much more of a culture of reliability and professionalism.

There were two events that occurred. This passing weekend the site was down periodically during the day. I reported this to the service provider. They said that other of their clients were abusing the service and they were shutting down the server (which included this site). Other times when I brought it up with them they denied it (for instance a technician got back to me today about one of the I reported on Saturday telling me that my site seems to be loading fine at the moment and couldn’t know of any issues that took place on the weekend).

The second event happened on the previous weekend. In this case I spent about 15 hours of my time on the problem. In fact the providers customer support deleted some of my backups before I had a chance to download them. Needless to say, at that point I started to shop for a new provider. I had it picked out but I made the switch on the passing weekend when the site started to be a problem again.

If this pattern keeps up that means I’m in for more issues this weekend. I have other sites at the old service provider so I will work at moving them to the new provider.

Overall traffic. Here you can see the two outages.

Search traffic. As you can see the search traffic (new visitors) took a larger hit and actually dropped to zero on one day.

I just read the “Service Guarantee” of the old provider. It is only a 30 day guarantee. I feel short changed since I have a three year contract with them. I need a site that’s reliable for more than 30 days.

The old provider is HostPapa and the new provider is BlueHost.