Russel-Henderson Light Monoplane (oz14151)

About this Plan

Russel-Henderson Light Monoplane. Radio control sport-scale model, for 20 - 30 engine and 4 functions. Scale is 1/6.

Direct submission to Outerzone.

Update 25/10/2022: Added article, thanks to RFJ.

Quote: "Plan Feature: Russel Henderson Light Monoplane of 1929. A 48 in span 1:6 near scale model for 4 functions and .21 - .30 4-stroke engines.

Having built a fair number of model aircraft, I am convinced that with modern power plants, materials and radios, it is possible to make a flying model of almost any aircraft that has flown. In the present case, the reverse may apply and the inability to make the model fly - at first - may indicate that the original had serious problems.

The Aircraft: In the late 1920's, the homebuilt scene in the United States was just getting started. The Flying Manuals published by 'Modern Mechanix and Inventions' described how to build and fly your own glider or plane. Engines were expensive but you could make your own from a pair of Harley Davidson cylinders. Perhaps the most popular was the four cylinder air-cooled Henderson motorcycle engine which weighed 120 lb and gave all of 23 hp.

In 1989 the Experimental Aircraft Association republished two of these manuals and I used them to build a 1/6 scale model that could be taken apart and packed in a suitcase to fly with my friends in other countries. Because of its small size, I chose the Russel Henderson Light Monoplane as a subject, even though the photographs showed half the completed aircraft.

The designer Chas B Russel stated that for those unwilling to pay $1500 to $2000 for a factory built plane, they could build their own. The drawings given were reasonably complete but I was surprised by his statement that the centre of gravity must be at least 32% of chord, under the centre of pressure 'otherwise your aeroplane will not leave the ground'. He described how to get it there by balancing the fuselage on a trestle and moving the engine back and forward, but made no mention of allowing for the weight of the pilot. If I had followed his instructions to the letter I would have ended up with the CG at 69% of chord when I was onboard!

For the model I arranged the balance point at about 25% of chord, in line with modern practice but the tail looked rather small, as shown on the drawing. I managed to persuade myself that it did not have a small tail, it just looked a big wing, but no way could I get it to take off as it ground looped furiously in either direction in spite of eight attempts at take off.

Back to the drawing board, as I felt the tail was not only of too small an area, but of low aspect ratio and blanketed by the stubby fuselage. I made a new one, with all the surfaces enlarged 70% in area and this time the model flew as I had hoped. I noticed that the photos of the part-completed aircraft showed a fin and rudder, apparently of the shape and size with which I ended up. Possibly the model is more accurate to scale than Mr Russel's published drawing!?

Since the article only showed the partly finished plane, I could not help but wonder whether Chas B Russel encountered the same problems that I did. I therefore wrote to the fount of all wisdom on homebuilds, Mr Paul Poberezny, in Oshkosh WI, and he kindly published a short article in the Sport Aviation Association magazine, asking whether anyone had any knowledge of flights by this 1929 aircraft. There is no answer as yet, but I will keep you informed.

The Model: At 48 inches span, the model breaks down into components of not more than 24 in, the wings coming in half and the horizontal and vertical tail surfaces being held by a single bolt. The wing struts used Kwik links and the undercarriage is removed by four bolts so that the whole lot can be packed away in a suitcase, together with your wife's clothes and toiletries!

US size 4-40 bolts and T-nuts (ie spike-nuts or captive nuts) or the equivalent metric size (3 mm), are used to assemble the model.

Any of the .20 - .30 size 4-strokes should be satisfactory. I like the HP21 which turns an APC 9 x 6" at about 9,000 rpm. This is not an aerobatic plane but then, with 23 hp neither was the original.

I have not tried electric power but see no reason why it should not be successful, but it will not be much quieter than with the HP21!

There are no difficult bits such as canopy mouldings or retracts, so as Chas B Russel put it: The best way to begin building your plane is to get started!

Construction of Wings: This is conventional with four 3/16 square spars. Build the wing halves flat on the plan and 1/8 liteply inserts for strut fixings, servos and wing joining plate. Use scrap 1/8 liteply to reinforce the inserts to take screws and nuts. The ailerons are hinged with Mylar at the upper surface, with the pushrod and horn underneath. Add the ailerons only after covering.

The tubes for wing joining rods are glued with epoxy to 1/16 ply webs between the spars.

After sheeting the centre section, add the 1/4 balsa inner ribs. They will be cut away to clear the cabane strut pylons.

The false ribs are added from scrap 3/32 balsa after the full ribs have had their capping strips added. The false ribs are then cut down to size using a straight edge and mini plane.

Tailplane: The tail surfaces are cut from 1/16 balsa cores and spars, ribs and leading edge added, also from 1/16 balsa. Turn the surface over and add the spars, etc. for the other side.

The stabiliser has a triangular key underneath the centre, to fit into the rear fuselage and the fin is clamped down to hold all together with a single 4-40 bolt.

A wire joiner couples the elevators and control horns can have a clamping plate on the other side or be screwed to a ply is insert.

Fuselage: The basic fuselage sides are made from 1/8 liteply with 3/16 balsa stringers at the rear. Doublers take the T-nuts for the undercarriage fixings. Use 3/16 stringers for the rear decking and two stringers run down each side of the fuselage and are tapered in, with a mini plane fore and aft.

The tank box is made from 1/8 sheet balsa and hardwood bearers are used for the servos. I like to install the servos before completing the top and bottom of the fuselage.

The cowling sides are from 3/8 balsa with the built up engine bearers glued to them. Install T-nuts for the engine bolts before sheeting the underside of the cowl. Don't forget the throttle pushrod! No removable cowl is needed as engine bolts can be accessed through the top of the cowl. Two 1/8 ply hatches, held by small wood screws, are provided for battery and radio hatches.

Two 1/4 square balsa pushrods for rudder and elevator exit on either side under the tail.

Undercarriage: The undercarriage is something of a cat's cradle. The easy way to make it is to bend all the wire parts and tin them for joining. Then solder the mounting plates to the front and rear legs and screw them to the fuselage. The remaining joints can then be bound together with tinned copper wire and soldered. Silver bearing solder rather than electrical solder is advisable for this job. The axle is held in place by rubber bands round the bungee hooks. The 3-1/2 inch vintage wheels are held in place with collets. Use Dural alloy, not aluminium for the tailskid!

Radio Installation: A miniature receiver is needed with five servos. Hitec HS 205s would be fine for the rudder, elevator and throttle, although I used some old Fleet servos. A pair of HS80s sub-miniature servos fit flat in the wing for the ailerons, stuck with double-sided servo tape to the ply mounts..."

Supplementary file notes

Article.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction