You MUST be a MEMBER in Hip Pocket Aeronautics "Builders' Forum" to REGISTER for access to the Plan Gallery.
Forum Members can visit This Topic in the Forum to Register. Logging In to the Forum is required.
Home / Free Flight / Outdoor Rubber Power Sport / Hep Cat by John Barker Top Plans  New Items (Last 10 days)  Search  

Registered users

Username:

Password:

Log me on automatically next visit?

» Forgot password

 
Random Plan

Cessna (Plan and Parts)
Cessna (Plan and Parts) (hlsat)
Scale (Foam-Depron)
Comments: 1
Downloads: 1319

 

Hep Cat by John Barker
Hep Cat by John Barker

             << ZIP may not work for everyone

Hep Cat by John Barker
Description: NOTES ON 'HEPCAT' DRAWINGS
I think that I built the first 'Hepcat' in 1944 and it was lost on its fourth flight, 37 minutes oos. In the next few years I and my club mates built a lot of them because they kept flying away. However with the speed of development at that time they soon became obsolete as first line competition models and I forgot about them for about thirty years. In the early 1980s Vintage became all the rage and Bob Jones asked if I minded if he produced a more accurate drawing. I was delighted and gave Bob what help I could and I think he eliminated the errors mentioned below and produced a good representation of the 'Hepcat' as flown in its early years. Since then I have built three 'Hepcats' incorporating some of the modifications mentioned below. I am sure that neither Bob Jones nor myself has tried to change the model in any way that was not in the spirit of the Vintage rules. Bob gave me a copy of his drawing but unfortunately in the turmoil of packing up for a house move I cannot find it at the moment so what follows is from memory.
ERRORS ON THE 1946 DRAWING
- The flat portion on the top rear of the fuselage, where the tailplane sits is drawn 4.5" long whereas it should be only be 4" to match the tailplane centre chord.
- One point which is completely unimportant but may amuse you. I was an apprentice draughtsman at that time and thought I knew about stress raisers so I was concerned with the junction of the nose sheeting and the longerons. I therefore put a triangular fillet in the corners, about 0.25" long on the short sides and sanded a curve into the hypotenuse so as to blend the nose sheeting to the longeron. Completely useless of course considering the run of the grain in the fillet! The staff draughtsman replaced it with the peculiar 'nothing curve' which you see on the plan.
- The drawing work on the propeller assembly is not good. The root is too thick to fit into the hub and the blade will not fold unless the root is radiused in some way. I have wondered if the block details were copied from somewhere else because I don't think I would ever draw one in that fashion.
- Most of the other errors were in dimensions and were largely unnecessary anyway. The 8.25" and 6.75" dimensions should run from the next rib inboard. The fin dimensions are confusing and on the original the tip was not so pointed. The propeller balance arm is given as 2.5" but should be nearer to 4". One dimension which might raise some eyebrows is the front wing mount height of 3.5" but which actually was 3 and 1/32 inches.
CHANGES I HAVE MADE
- The plan shews the undercarriage leg coming from the center of the fuselage. The first model was made like that but the stupidity was immediately apparent and later models just had the leg running straight down at the left side of the fuselage. It soon became apparent that fixed undercarriages are a great nuisance to carry around and recent builds have used a removable wire leg that plugs into a flattened aluminium tube in the fuselage.
- I widened the nose of the fuselage 0.125" to take a winding tube and changed the propeller shaft hook shape to accept an 'S' hook. I also now use a wooden propeller shaft stop instead of a wood screw.
- When the BMFA changed the Vintage rules to permit wire hubs on folders I used a wire hub but now the rule has changed again I have reverted to a 'ply box' hub. The hefty looking ply box hub is actually lighter than the modern looking wire hub.
- I have fitted tipping tail dethermalizers.
- I use hard balsa wing rails instead of bamboo.
- I have used laminated (wound) wing tips.
- For convenience of carrying and storing I have made recent versions with removable tip fins.
- I use some tiny fillets where the wing mount wires leave the fuselage to give something to which to stick the tissue.
John Barker 2013.
Keywords: Hepcat, Oldtimer, English Lightweight, John Barker
Date: 11.25.2016 23:23
Hits: 946
Downloads: 336
Rating: 5.00 (1 Vote(s))
File size: 320.2 KB
Added by: DerekMc

Comment:
There are no comments for this image



Previous Plan:
Half sized Judge Wakefield  		  Next Plan:
Hepcat (Single Sheet)

 

 

RSS Feed: Hep Cat by John Barker (Comments)