Blackhorse Travel Air by Tom Laird. 19/4/2004

Wingspan   

1550mm / 60 inches

Length

125mm / 47.5 inches not including engine

Propulsion

Irvine 53 2 stroke. APC 12 x 6 prop. Model Technics Contest 10 fuel (10% nitro)

Control

5 channel radio(rudder, elevator, throttle and 2 for ailerons)

Price

62 ish

Construction
Balsa fuselage, built-up wings (capped wing ribs). Tail dragger.
Notes on buying a Blackhorse Travel Air

The dilemma faced by beginners is very simple: what to buy as a first low wing model. At this price, it is not surprising that people opt to buy the ready-built model. Everything is supplied: pre-built fuselage, covered wings, tail, full undercarriage including wheels, all control linkages and all nuts, bolts & washers which are required to complete the plane.
However, from experience we now know that, as usual with ARTF's, that some additional bracing is required, and the clevises changed for metal ones. The hinges supplied in this case were acceptable, metal and pinned in place.

The first impressions were very favourable - a very neat model. Sealed canopy, pilot in the office, engine mount fitted and a spare in the box, all control surfaces fitted and pinned with no large gap. All items sealed in their own tough plastic wrapping bag. The wing ribs are capped giving additional strength. The wing comes with thread already in place to pull the servo cable through. The covering has good overlap. Now for the surprise - the firewall, undercarriadge plate and the servo tray are all braced. Somebody, somewhere knows what they are doing :)

The fittings kit is first class, with acceptable horns and clevices, although I changed the plastic clevices for metal ones, and fitted my favourite control horns (as used on the Ripmax Nova 40). The fitting bag even had the little bits of fuel tubing which slide over the clevices as a locking mechanism, and also had the foam to wrap the tank, bettery (that's posh for battery) and receiver in. (I changed the foam as well). 2 spare wing bolts were supplied.

As usual remember that you need to fuel proof the engine bay and fuel tank area.

The Build
I am generally fairly unimpressed by the quality of the building instructions that come with most kits (Glen's Models excepted). This kit however is first class and comes with a full colour A5 booklet and is very comprehensive. The final sentance should give an indication - make sre the aerial is not still wrapped around the receiver before you fly.

The first thing I did was to check the wing brace. As it was a bit slack for my liking I added a 1/4 inch length to the ends, and a 1/16 along the top, making a much tighter fit but still leaving enough space for the epoxy.

I then checked the smoothness of operation on the control rods. One needed a slight clean to remove some gunge after which it was okay. Remember to bend the rod away from fuselage at the exit hole.

Tank Mod
I have also added the usual piece of brass tube inside the tank, between the outlet and the clunk. In the event of a rapid stop the clunk can be thrown forward and gets stuck, resulting in fuel starvation after about 10 minutes. I also used plastic tie-wrapsto secure the fuel lines to the tank on the outside, reducing the risk of air getting in. See here for details.

I used the Irvine 46 from the Nova and felt we should get reasonable performance. I noticed that the carb was going to be quite high above the tank centre line, but "knowing better" ploughed on regardless. MISTAKE!!. One minute the engine would run, the next it would not. What to do? Invert the engine? That would put the carb below the tank centre line - not a good idea. Drop the engine onto the bottom of the bearers? That would change the thrust line although how noticeable I could not say. Rotate the engie? Sounds the best bet I think.
So, engine out and rotated through 90 degrees. Here you can see the difference. The 1 inch height difference was reduced to about half an inch. Still not ideal but better.

The big problem was the original blind nuts were going to interfere with the new positions, so a quick tap with a 4mm screw and a hammer, and they popped out. A new bulkhead was measured and made from 1/4" marine ply (thinner laminations than normal ply) and epoxied in place. Note the recesses on the original holes. This allows the new bulkhead to sit flush, otherwise the flanges on the new blind nuts would give about a 1mm gap between the old and new bulkheads.

Dont forget to fuelproof the new bulkhead.

This is a nice touch. The servos are well protected and it is a short control rod to the aileron. Note my favourite horns and the fuel tube retainer on the clevis at the servo.

The supplied undercart looked good but only lasted about 3 landings before it collapsed. The legs were just crimped together so I replaced the supplied undercarridge with the one shown in the pictures as it is much stronger. You will need to glue a 1/4 inch plywood inside the model to give the saddle clamps something to attach to. This is best done at the assembly stage and not afterwards. Remember to buy larger collets and larger saddle clamps.

 

 

Since my son wanted a yelow-top / black-bottom model that he could see in the sky, as opposed to the nice white and blue camoflaged colour scheme, we over-covered the model with solartrim.

The Flight
 

I am pleased to say that the model flew well on its first flight. A few circuits to trim it out, a basic Bronze schedule then in for a landing. Wing off, check everything is okay, refuel then back up again. I had set the full aileron throws to more than the recommended since it was still very windy, and set the reduced rate to those in the manual. It flew well on reduced throws so I'd say the 6mm quoted is good enough.

Engine & Propeller
On the engine front I would say that the Irvine 46 has enough power to cope with the windy conditions we have to put up with, although a downwind loop or 1/2 cuban is not done with any confidence. We have been flying on a 12x6 Master Airscrew Scimitar, and are about to try an APC 11 x 8.

The Summary
A good model let down by the usual ARTF trainer problem - useless undercarriage. The wings have a very good airfoil section and the model can land very slowly without any tip stalling characteristics. Most importantly, there is virtually no gap between the wings, tailplane, fin, and the respective control surfaces due to the type of hinges supplied.

Ongoing assessment
The Irvine 46 must have sustained some damage as the bearings were pretty noisy / worn and has now been replaced with an Irvine 53 (same carb and silencer as the 46). I have also gone from 5% nitro to 10% and the difference is amazing. Those big loops are now a breeze and done with a lot more confidence. One thing I have noticed is the shape of the leading edge - it is not a continuous curve, more like a flat with a curve at the top & bottom. It might be worth a look at http://www.rcuniverse.com to see if there are any comments on this model.

This model can cope with the wind, and I have seen no evidence of tip-stalling when landing. Being a taildragger it is a bit succeptable to groundlooping on tarmac if there is a strong crosswing but on grass is very manageable. Straight into wind it will take off very nicely indeed.

This was my son's first low wing model and does that job perfectly. However if you want to learn and practice the aerobatics schedule for instance then I would cerainly put it on the short list but would take advice to see what else might be suitable.

All these comments are based on my own circumstances which include a computer radio which gives me the ability to adjust control surface travel to the nearest 1%.

Remember, that as with all ARTF models, they are built to a cost and within a certain time limit, which means they cannot have had the tender loving care that you would furnish on a kit, were you to build one instead. Even if you have not built a model before, the bulkhead and undercarriage mods are well within the capabilities of most people and could be enough to get you started on the road to building your next model.