The Nose Cowling
Back (Egad!) so many years ago when my son first started this project I helped him out by shaping the nose cowls out of PVC pipe. I had no concept of the scale of a Thunderhawk but I figured on an aircraft of this size that a man could stand upright in the intake duct.
I used a table top belt sander to obtain a satisfactory rough shape and that is where I left the cowls assuming once the rest of the 'Hawk was well underway I could always polish them to a finished appearance.
Now 4 years later and I having inherited the project my son being away in college and no time for such things I take up the completion of the cowlings still as yet unpolished.
Below you see an assembled cowl and the three components that make it up
http://i.imgur.com/6Rk1knl.jpgI plan to make the fans today.............
Post Merge: July 10, 2013, 10:42:53 AM
In the future, please use the modify button. Double posting is against the forum rules, and for that reason, the system merged your posts.
How Many Blades?
After viewing a number of intake fan assemblies of Thunderhawks I have decided on 16 blades; the reason being expediency.
Were I to go more and readily divide the fan by 4 the next logical number of blades would not be 20 but 24. 20 is out because of the necessity of dividing each quarter of the disk into five blades. Since the disk is only 25 mm in diameter the chances increase having different width blades regardless how sharp your pencil/ scribe may be. 24 blades though easier to calculate also increases the margin for error.
If memory serves an L1011 Rolls Royce engine has around 32 blades but those blades are close to a meter long (From the center of the hub) and that is a much larger aircraft than the Thunderhawk is purported to be.
Post Merge: July 10, 2013, 02:36:32 PM
In the future, please use the modify button. Double posting is against the forum rules, and for that reason, the system merged your posts.
Fan Manufacture an Easier Way for Larger Fans
16 blades seems the best for while easy to fit accurately on a disk it is busy enough to simulate an intake fan especially if the cuts are made on an angle to augment the illusion of a fan.
For that reason I have selected styrene 1,0 MM thick.
I began by dividing the disc into quarters:
http://i.imgur.com/0X8BhzN.jpgand then into 16 segments the ends of the blades coincidentally worked out to 5,0 mm wide.
I then glued a small hub to the center of the disc to act as a guide for the inner end of the cut (To prevent the blades from being cut off completely.):
http://i.imgur.com/NkfqUMw.jpgEmploying my chisel blade I cut into each segment at approximately a 45° angle so the edges of the blades appear to overlap.
http://i.imgur.com/CruF7Ux.jpgAfter all the cuts were made I glued a small disc to the back of the fan to reinforce the axis point and with needle nose pliers twisted the blades to give a fan like appearance.
Post Merge: July 11, 2013, 04:36:04 PM
In the future, please use the modify button. Double posting is against the forum rules, and for that reason, the system merged your posts.
A Mélange of Ideas
There are so many different styles of nose cowls for this model most of them wrong but some good points to most as well.
I am picking and choosing that which takes my fancy from each.
The image below shows some interesting features and an out right wrong namely the fan too close to the front of the cowl.
http://i.imgur.com/cbp0I6R.jpgWhat purpose the flaps are on the outer circumference of the cowl is unknown but they are an interesting feature and therefor included.
http://i.imgur.com/99f2s6f.jpg