Pegasus Models Hornet - HWDMAC Winter Build 2018

[Brian Seymour]

This year the High Wycombe and District Model Aircraft Club is having series of club meetings to get together and build Pegasus Models Hornets (used to be Galaxy Models Hornet). This blog has been started a little late as our final scheduled meeting is tomorrow night and a couple of models are almost ready for their maidens.

With the assistance and encouragement of Richard Wills of Warbirds Replicas we decided that the Hornet is an ideal combination of build simplicity, flight performance, and price for our group build.

The pictures below are Richard's and Glynn's completed (and regularly flown) models. I'll follow up with pictures of the my build and, hopefully, a few of my fellow builders (there are 12 of us) will share their experiences.

[Old Geezer]

Trad' British kit - don't you just luv 'em. When I first started flying power in t'70s my first power model was a Galaxy Escort, tough as old boots (doped nylon covered), safe predictable trainer with a 2nd hand OS25. Also had their Spatman too - overpowered it was huge fun. Then a Magician - another toughie, nice flyer too.

These Hornets look a bit gangsterish - if they fly like the smaller Gangsters (48 or 52) they could be real fun, so very tempting - what are they powered by? Is anyone electrocuting one? (I have been on the dark side for years.)

[Brian Seymour]

Quite a few of us are going for electric, we are aiming for ~500W using 3s or 4s packs. The kit is design for ic but making adaptations for electric aren't particularly taxing and you'll see how we went about in the ensuing posts.

The build isn't complicated but we aimed to get the bulk of the build done in 3 sessions of 4 hours so 5min epoxy and CA were the order of the day but we used PVA for anything that could be pinned, clamped, or otherwise retained and left overnight.

I haven't got any pictures of the early stages of the build but a few of my fellow builders may post pictures, for now a bit of imagination will be required. The build starts with gluing an extension to the left hand fuselage side at the front, the right hand side is left short to allow the cylinder head of the engine to protrude. Electric powered model need the right hand side to be modified to be the same the left hand side. Guy cut out the pieces required to extend the right hand fuselage sides in preparation so that on the build night just the scarf join needed cutting into the right hand fuselage side. The extensions were glued in using CA.

Next up is gluing ply doublers to the balsa fuselage sides. For this we used a spray contact adhesive, the extents of the doublers were masked off to prevent overspray and the adhesive was left for 10mins before the parts were joined.

Whilst the contact adhesive was drying we switched to the wing panels and glued the wing tips on with 5min. epoxy.

With the wing tips curing we switched back to the fuselage and stuck the ply doublers in. The fuselage formers either side of the wig were next. For this stage we marked lines on the inside of the fuselage side to assist with getting in the right position and perpendicular to the top edge of the fuselage. 90° blocks were used to ensure that the formers were square to the fuselage sides and CA was used to tack them in place. With the 90° block removed beads of CA run down either side of formers to ensure a good bond.

Guy had setup and brought along his fuselage jig so the fuselages were put in the jig and the formers and rear end glued in situ. Whilst in the jig, the underside sheeting was glued on to ensure a dead true fuselage was built by all.

The turtle deck is veneered foam part ready to be glued on, this is a bit tricky although a darn sight quicker than builder and sheeting one. For this we put rows of pins down the top edge of the fuselage sides to make the deck conform to the profile of the fuselage and then either: used 5min epoxy and held the turtle deck down until the glue cured, or used PVA and rubber bands to hold the turtle deck down and left it to set over night. Both methods were tricky but effective.

The leading and false trailing edges were glued on using PVA and held in place with either masking tape or pins and left over night to dry.

That was about all we had time for on the first evening, I had thought that we would get further but almost all of my fellow builders hadn't ever built an rc model kit before so in hindsight I think that folk did rather well.

We couldn't have got the builds done as quickly or as well without the help of a few of the club's seasoned builders lending a hand so many thanks to Guy, Graham, Charles (who was also building a kit), and Steve.

[Cuban8]

My first proper aerobat was a Hornet, goodness knows how many years ago, bought at Sandown. It's great to see that they're available again. Super model, easy to fly and tough enough to take a few knocks. Not a lot of ground clearance for the prop IIRC, and I'd have thought I'd originally have gone with a 10/11x6, with a .46 two stroke - a long time ago now and I can't remember. For 'leccy, 500W and a smallish prop sounds a bit marginal and might not give brilliant duration as the airframe is no lightweight. Interesting project and I'll be following progress with interest..

Might even build one myself for old times' sake.

[Richard Wood]

The Hornet looks very similar to the sadly no longer available Galaxy Scorpion.
I had an electric Scorpion which flew very well on a 4S setup with around 600W.
Cuban8's comment about 500W being a bit marginal is good advice.
Anyway, good luck with your Hornets.

[Brian Seymour]

Thanks for the encouragement men, the Scorpion looks ace with a cracking finish.

Most of us have gone for power setups that are capable of more than 700w so we have got reasonable scope to turn up the wick. That said, the Hornet is a bit smaller than the Scorpion (52" wng span) and the AUW on my one is a shade under 4lb so we are in with a chance at 500W.

In between the first and second build meetings folk cracked on at home to get the fuselage blocked out:

The turtle decks were glued on as described above:

 

The one below was glued with PVA and left over night - held just as well as epoxy glued ones.

 

The back of the cockpit is supplied a little over size so the actual size is marked on, trimmed roughly to size, glued on, and then sanded to size.

 

The firewall was marked out with the location of the front nose leg, as my one is electric I have mounted it slightly lower to give a bit more clearance for the prop. I made shallow grooves in the front face to help locate the nose leg.

 

The location of the firewall was marked on the inside of the fuselage to help align it correctly. Elastic bands were used to pull the fuselage sides in and clamp the firewall in place and it was glued in with CA.

 

The underside of the nose section was glued on next, the front end needs to be pulled in to match the nose ring. The nose ring was dry fitted to gauge how tightly to clamp the front end, the underside sheet was glued in place with the clamp holding the fuselage sides.

 

The firewall has got reinforcement strips that run down the edges, these were sanded to make them a perfect fit and glued in with CA.

 

The cockpit sides glued on along with the cockpit floor.

The top deck sides have an area which is left un-glued so that it can be easily cut off to form a hatch. The top deck is glued on the length of the sides.

 

That little lot of jobs is very satisfying as it only takes around an hour and transforms the fuselage.

Edited By Brian Seymour on 26/02/2018 22:29:26

[Richard Wood]

Good progress Brian . The veneered foam rear turtle deck is a great idea &
was common to the Scorpion - strong, light & keeps its shape.
I'd love to build a Hornet - just hope your lads haven't cleared out all of Pegasus Models'
stocks.

Edited By Richard Wood on 27/02/2018 09:05:14

[Brian Seymour]

Cheers Richard, I think that we have left a few for other folk...

I went back onto the wing to fit the undercarriage blocks. Slots are pre-machined into the wing which need the ends squaring off to take the blocks. The blocks were laid in position as a template and the veneer was score with a scalpel until it was cut through.

The foam beneath was cut to dept and the corners picked out.

The undercarriage blocks are doubled up in the end closest the wing root so the foam needs to be cut deeper to accommodate it. I used a scalpel to make a grid of cuts to depth, picked out the squares of foam and then finished the base with a bit of sand paper - a bit OTT but I couldn't help myself.

The blocks were glued in with epoxy.

With that curing, I switched back to the fuselage. The top deck and underside of the nose were planned back to be flush with the fuselage sides so that the split line for the cowl could be marked on and pre-cut before sanding. The cut on the top deck forms the front of the flight pack hatch and, as it hooks in at the back, needs to be at an angle - 45° seemed as good as any. The pictures below are of my brothers fuselage, annoyingly, I hadn't realised that the front needed to be at an angle so I have got a slight gap on my one.

The razor plane was deployed again to chop the radii roughly onto the corners and, whilst I was in "the zone" for razor planning, the balsa work on the wings (tips, leading edges, and false trailing edges) were planed roughly to shape which made for a nice little pile of savings:

The balsa was then finished off with sand paper so this stage was rather messy but also rather nice to see finished shapes coming through.

[Brian Seymour]

With the fuselage sanded the hatch and cowl were liberated with assistance from the razor saw. Ply tabs were glued to fuselage sides and bottom to bolt the cowl to. The pictures below are of my fuselage, I have a sheet of lite-ply so I made the tabs from that but there is enough scrap poplar ply in the kit to use that for the tabs.

With the tabs glued in the cowl was re-fitted and holes drilled trough to the tabs. Screws were fitted and then removed and then thin CA was run into the holes to toughen them up a bit.

 

Thin CA was used on the cut edges of the of the cowl/fuselage spit to toughen them up. Once the glue had set the cowl and hatch were re-fitted and the front end was given another once over with abrasives to blend them back in line.

I must confess that splitting the front of the fuselage off to make a cowl on the electric models was Guy's idea, possibly obvious to everyone else but it hadn't crossed my mind. He made a mock-up of the font end to demonstrate it complete with the motor mounted so it was dead easy comprehend and copy.

With the fuselage well underway I switch back to the wing, gluing the halves together. I used epoxy and left them overnight.

Edited By Brian Seymour on 01/03/2018 13:51:15

[Geoff S]

Must be fun building a model as a group. It must help if one has a difficulty there's always another who's found a way round it.

I did the turtle decks on my DB Cirrus Moth (being built as a Gypsy Moth) last week using UHU Contact adhesive for the edges and Titebond Aliphatic resin for the contact with the formers. I know that's using 0.4mm ply rather than balsa (I assume that's balsa) but it worked well and avoided the need for elastic bands.

Geoff

[Dwain Dibley.]

Posted by Brian Seymour on 27/02/2018 22:29:32:

The balsa was then finished off with sand paper so this stage was rather messy but also rather nice to see finished shapes coming through.

I think, especially with the vintage and old school designs, the planing and shaping phases are the most enjoyable.

Those models are looking the Mutts BTW, and look like they will be great fun.

D.D.

[Brian Seymour]

Cheers men, there are a few alternatives to get the turtle deck on, the contact adhesive and aliphatic method sounds like an excellent method. The turtle decks are covered with obechi but no reason that UHU contact adhesive wouldn't work unless it eats foam - the contact adhesive that I had eats foam so we couldn't go down that route.

I'm with you DD, once I got the hang of sanding (and a decent set of abrasives) I began to find the shaping stage very rewarding.

I haven't got many pictures of the rest of the build so I'll see if I can get some of the other builds as my one is pretty much ready for flying strip.

[Richard Wood]

Nicely done job & well executed cowl arrangement - often a tricky part with all balsa
electric models.
Planing & sanding a square box into a well shaped fuselage is a satisfying process
and the pile of balsa shavings looks familiar - but at least it's easier to clean up &
healthier than all that wood as balsa dust. Usually try to do the sanding part outside.

[Brian Seymour]

Cheers Richard, credit to Guy really as I would have ended up something ludicrously complicated if he hadn't made a mock-up of the idea.

Geoff, building together as group is great, it tuns a usually solitary activity into a social one. Lugging the tools around is effort but when you get see how other folk are putting models together and you get to demonstrate your own techniques it is really good - a rich blend of picking up tips and showing off!

With the wings shaped the next step was to glue them together. The top surfaces are kept flat so the dihedral is no more than the tapering of the wing. I used epoxy to join the wings and laid a sheet of cling film over the building board to prevent sticking the wings to it.

Next up was the aileron servo box, I am using a pair of 9g servos for the ailerons so the pre-cut recess for the servos needed extending slightly. The box is lined with 1/8" balsa, where possible I ran the grain of the balsa across the wing join, I know it doesn't do much for the strength but it is simple enough to do.

For the aileron torque rods, I set them slightly into the false trailing. I hadn't used torque rods for a long time but I did recall that setting them into the false trailing edge made their operation smoother. The centre section trailing edge has a slot pre-machined in it to clear the torque rods so it only needed small sections cutting out to clear the torque rod bearings (for want of a better word). Annoyingly, I managed to glue one of the torque rods in pace so the trailing edge had to come off, the IPA deployed, and the trailing edge glued back on - turned out to be a simple fix.

The wing is located at the front with a dowel that is fixed in the wing and locates in the former in front of the wing. The hole in the wing was made with a power drill, it was tricky to keep the drill from wandering either side of the glue and, although the hole in the leading edge was snug, the rest of the hole was somewhat baggy. I used Gorilla glue to fix the dowel in the wing in the hope that it would expand enough to hold it tight - it seemed to do the trick.

[Brian Seymour]

The builds have been coming on, we had an extra build night yesterday and it was great to see the models nearing airworthyness.

There weren't quite as many as usual but the place still had a buzz about it and, with folk at the covering stage, we also set up a Solarfilm-ing station for folk crack on with covering.

Having: flown, crashed (after several flights), and repaired my one I can say that the Hornet is great flyer and stable enough in the gusty breeze that we have been flying in. She is a refreshing change from modern aerobatic planes with a good turn of speed and solid stability. Add to that, she is a tough model, given the speed that she went in at I was pleasantly surprised that she didn't end up as shrapnel and the repair wasn't too much like hard work.

The stats (pre-crash) for my one were:

• AUW:- 1850g
• Motor:- Turnigy SK3 3548 840kv motor
• ESC:- 60A Hobbywing Platinum V4
• Flight Pack:- GensAce 4s3300mAh 25c
• Power:- 525w (with Turnigy 10x8 electric wooden prop)

[Richard Wood]

The Hornet is a very good looking model & is an ideal candidate for electric conversion.
Its longish forward upper fuselage is easy to use for a battery hatch as you've done.
Thanks for the report - I'd like to try one.
They do tend to be tough these foam wing traditionally built models.

[Brian Seymour]

Cheers Richard, yes, she is a nice shape from the off, the only thing I changed whilst fixing my one was to round the front of the cowl to be marginally bigger than the spinner. That was partly due to the amount of wood that got pulverised at the front end.

For the build nights, folk tacked the wing trailing edge and ailerons to the false trailing edge so that they could be sanded to exactly match the wing profile, it's a neat idea that Guy came up with and a lot easier than the sanding than ailerons after hinging (which is what I had done). A couple of folk used masking tape on the wing veneer and the last 1/8" of the ailerons and trailing edge as a further guide for sanding and to prevent sanding too much - I'll definitely be using this technique on my next one.

With the ailerons and trailing edges still tacked on, the wing fixings were tackled. The dowel at the front was tackled first. Guy had simplified this by making some plates to go on the front of the wing from 1/16" ply, neatly cut to match the surface of the former with a hole drilled in for the dowel. The plate was tacked to the former (using the dowel to locate it), the wing accurately positioned, the wing then glued to the plate, and then the plate cut from the fuselage. The hole in the plate was used as drill jig to make the dowel hole in the wing and then the dowel was glued in place.

The wing nut blocks were glued inside the fuselage and their positions were marked on the top surface of the wing, this enabled us to get a good idea of where to put the wing bolt holes.

The wing bolt holes are drilled through dowels which are inserted into the wing. The dowels go in perpendicular to the underside of the wing so their position from the trailing edge was measured off the plan and marked on the top and bottom of the wing - due to the angle that they go in at, the top is a different distance to the bottom. Using the centre marks, the dowels were drawn onto the surfaces of the wing and discs of veneer were cut out and a hot wire melted through the foam to make the holes. This left a little bit of sanding to open the holes out to the exact size of the dowels. The dowels were dry fitted, pushing them flush to the underside and marking the excess on the top side The dowels were removed and the excess was cut off using a hacksaw as nothing else made much of an impression on them.The dowels were then glued in using epoxy.

The wing was then fitted to the fuselage and lined up by measuring the distance to the rear tip of the veneer on each wing to the middle of the back of the fuselage. Once the distance to both the left and right were equal, the wing was pinned in position. Holes were drilled through the wing dowels and the wing nut plates in the fuselage. The dowels are dead hard and most of us started with 4mm drill and then opened them out to 6mm. The wings were removed and the holes in the wing nut plates were opened out to 8mm to take the T-nuts.

The T-nuts were glued in from the back using G-clamps to force the prongs into the wood. This was a tricky stage for quite a few of us as the T-nuts didn't all go in straight and so they had to be drilled and re-tapped in situ.

As can be seen from the pictures, the drills wandered a little but, as the holes in the fuselage parts are drilled from the holes in the wings, the wings still locate perfectly.

Edited By Brian Seymour on 28/03/2018 13:55:03

[Nigel R]

Nice build(s)!

You chaps are fast workers, getting most of a build done in 3 lots of 4 hour sessions. I've barely stuck my tailplane together after that sort of time!

"The T-nuts were glued in from the back using G-clamps to force the prongs into the wood. This was a tricky stage for quite a few of us as the T-nuts didn't all go in straight and so they had to be drilled and re-tapped in situ"

This is exactly why I find it easier and ultimately as quick or quicker, to tap the wood instead of sticking a T-nut in - if you've drilled the first hole through the wing undersized then you already have a perfect guide hole for the tap. Run some thin cyano in after tapping, leave it to dry, clean it out with the tap, and jobs a good 'un.

[Brian Seymour]

Cheers Nigel, to be fair a few hours were put in at home between sessions but the model does go together nicely which helps keep the hours down.

Tapping the nut block rather than fitting T-nuts is a fantastic suggestion thank you, it gave me a heck of a Tefal moment! I'll definitely go for that on the next build, having fitted my ones and and assisted a few others with theirs I can't see how it could possibly take longer than messing around with T-nuts.

[Ken Lighten]

The trick with ‘T’ nuts is to use a bolt and a spacer or washer to draw the nut into position rather than using clamps

I’m in the middle of building mine at the moment and had to cut the rear deck off as, when aligning the wing, I found that I had managed to build a banana even though I’d used a fuselage jig which must be some kind of achievement! - successfully rescued thankfully

Enjoying the build even with my errors and following your group build

Ken

[Dwain Dibley.]

I always fit the T nuts into the bearer first, just hammer 'em in, and use CA to secure, then, once the bearer is fitted, use offcuts of the bolts sharpened to a point and screwed into the nuts, press the wing into place, this marks the wing where it needs to be drilled. A ply plate in the wing stops the bolts pulling through. Hope I'm not teaching you Guys to suck eggs.

D.D.

[Brian Seymour]

Cheers men, great suggestions, good tips for the next build. My Dad rectified the T-nut that went awry using the screw to pull it in as Ken suggested.