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Thursday, August 28, 2008

Building the slope Rockwell Aero Commander - PSS Part 1

Last night is started with scratch building my Slope PSS Rockwell Aero commander and I hope to have it ready for the PSS weekend in October in about 5 weeks time. I have decided that as I go along to photograph and post as many times as I can so hold thumbs for me. Here I go!!.

Rockwell Aero Commander The History

Why on earth a Aero Commander?. Well this plane as some of you might remember were flown by Rockwell’s chief test pilot, Bob Hoover. (Always dressed immaculately in a suit.- 1970 to1990). The Air Show’s those day’s were held at Lanceria about 20 Km North west from were I stay in Randburg and I use to attend these Air shows regularly. Bob Hoover use to do the most amassing aerobatic’s with this twin and some of them I will always remember.

For instance on take of he would take up the total length of the run way. Half way down the run way he would retract the undercarriage with out actually lifting of the ground .(IE. the under slung belly of the Aero commander only 1 or 2 feet of the deck and then at the end of the run way he would pull hard up in to a vertical climb until the Aero Commander would disappear out of sight. The P.A announcer would then inform you that he would come in from the south to start his aerobatic routine, and while every body is looking towards the South he would come diving in (both engines stopped and props feathered ) from behind our backs, nearly touching the runway then pull up into a slow roll with both motors still not running. Only after the completion of the slow roll he would start one engine and then the other.

Other maneuvers include a 8 point roll with only one engine running as well as loops and stall turns. One of Bob’s favored stunts was to fly a barrel roll maneuver( a positive 1 G maneuver) while pouring some Ice tea into a glass on the dashboard. To see a short video clip of this go to this link . (45 sec)
or view the full video here
Once he stopped the engines and feathered the props the Aero Commander became noting other than a full size PSS Plane and therefore the reason and my choice to build and fly this model for PSS weekend in October. Another point that should count in favor of this design is that the AR of the wing is 9 and that is on par with most model aerobatic slope soarers.

Building the Slope Aero Commander

The first thing to do was to get a good three view drawing of the Aero Commander and first prize is one with dimensions( even if it is in feet) this I manage to find it by typing in the word ”Rockwell Aero Commander ” in my browser search box and this time I must have been lucky. The very first hyperlink had everything I needed.

From this drawing you can now scale down to the wing span that you want (IE if the real aircraft has a span of 49 ft and you want a 7ft wing span the this (7/49= 1/7 0r one 7th scale . 7ft = +/- 2.15Meters.
So any full size dimension on your 3 view drawing must now be divided by 7 . I use computer printer paper to draw out the model 3 view and then made some small changes to make it look right.( The tip’s on the Aero Commander looks very narrow so I make it a bit wider and if the fuse looks to wide I make it a little narrower. The tail plane area may also need a bit more area to be on the safe side.)
Once happy with the model 3 view you can start with the construction. Before I continue I make a estimated calculation on the wing area and wing loading. In this case 910 sq in = 6.3 sq ft. At 10 Oz/per sq ft wing loading the all up weight will be 63 ounces and at 16 Oz/per sq ft. 100ounces ( 4.0 lb to 6.0lb) or (1.8Kg to 2.7kg.)

This will only be a guide and one can not really tell what the model will weight in the end at least you will have a goal to work to.

I plan to make this model out of foam and glass and if possible do not want to remove the foam inside the fuse so I will use a light weight foam and glass to lay-up the fuse once foam has been shaped to the 3 view plans.
Once I have done this I will publish Part 2 of the Slope Aero Commander. For now I am of to the workshop.


Derek Marusich said...

Hi Piet

What a great project and great documentation and info. You just have to put some wheels on it and do some of those one wheel landings like Bob does. I'll clear a patch of veld on top of the slope for you.

Can't wait to see it fly.


Piet Rheeders said...

Thanks Derek for moral support it Cover the fuse today with glass cloth and it felt like building a boat.
I will post Part 2 shortly and then you will see what I mean. I will have wheels fited but nly fo the static display.

Hope that I can finish this one on time you know all about the difficulties to build from scratch this is not going to be so easy as the CMP discuss that we built. Y the way sorry about the F3B com at berg . I was down and out for 4 days. Starting to feel better now .Still have a nasty cough.