Monday, 30 March 2015

Another record speed machine

If you've been following this blog for a while then you'll remember the CEA308 which I posted about way back in November of 2012.

That was powered by a Jabiru engine and set several world records.

From the same designer - Paulo Iscold - comes this latest machine the Anequim (meaning Mako Shark in Brazilian/Portuguese).

At first glance I thought this was a development of the CEA308 - but no - it is a completely new airframe. Built by students again - same as the CEA308.

They are going for the fastest 4 cylinder aircraft record - which stands at 260 knots. They are predicting 310 knots from this little beast.

You wouldn't bet against them - that thing looks tiny and so streamlined. The canopy has an explosive charge in it in case of emergency exit (the same as some military jet aircraft do).

They are using the canopy shape to control (minimize) the interference drag between the wing and fuselage.

Some videos of it are on this link:

They must have a skinny pilot...

Paulo at right. Note: Fences on the prop (built by Craig Catto).

Thursday, 26 March 2015

Week 189 - Engine, firewall

Hours to date: 1721.75

The upholstery and welding jobs are all briefed in. It will be about 3 weeks before I get the upholstery back - not sure how long with the welding but I think about 2 weeks.

In the meantime I can get on with installing engine accessories on the firewall.

I made up a mount for the oil ball valve out of 8 layers of carbon. Normally composites don't want to go round 90 degree corners but I managed to make this job work by taping one side down on the block of wood I was using as a mold and then pulling the carbon tight on the other side and putting a weight on it. It turned out good. Very strong and light. I could have just used a piece of Ali angle for this mount but where's the fun in that?

I cocked up the drilling in the firewall for the mount on the first attempt as I didn't take into account the carbon 'struts' which are bonded to the back, so ended up finding one of the holes inside of one of these struts. Something to bear in mind from now on!

Everything else went on fairly easily.

As you'll see below I've sealed the battery + cable with a special kit - available from Aircraft Spruce. It's easy to use and provides a gas tight seal on the firewall. I've yet to add the gasket 'goo'. I'll do that after the cable has been cut and bolted to the starter.

All that's left to install now is the oil cooler lines and oil air separator (when it gets back from the welders). The oil pressure sensor will just be held by a P-clip.

Figuring out P-clip supports for the main wiring harness.

Oil ball valve installed

Ditto - with homemade carbon mount.


Regulator rectifier

Battery + cable with firewall sealing kit

Ditto - gasket goo to be added and then hose clamps can be tightened.

Not bad for an afternoons work.

Wednesday, 18 March 2015

Learning from the Red Bull racers.

As you are no doubt aware, two time Red Bull air race champion Paul Bonhomme won the opening round of the series this year.

Paul puts a good bit of this success down to his new cowling.

It gets most radical underneath with twin oil coolers positioned way back inside the fuselage and fed by NACA ducts. As you already know I'm a big believer in getting drag further back on the airframe if at all possible. Whilst this is not the same as my setup it does share the same principles.

Also note the sawtooth edge on the main outlet. The only time I've seen it before is on jet engine exhausts where it has a silencing effect. See the Dreamliner's engine nacelle below. Incidentally this idea came from the mind of Robert Westley, who worked at RAE Bedford - just up the road from me.

After doing a bit of research I see that the sawtooth also has a effect on reducing the amount of turbulence when two airstreams are meeting - such as we have with the cold fast air outside the cowl meeting the hot slow(er) air exiting the cowl.

I see this part is also removable - as is the inlets. I guess this allows for a change to smaller or larger areas when the ambient temperature changes. It may be as cold as 15 degrees in some races and as hot as 40 in others. I will be doing a similar thing with my exhaust outlet fairing but my inlets will be fixed.

A couple of other things I noticed about Paul's cowl is the very long spinner and the air intake for the injectors that is angled upwards. I'm not sure why they do this but I am guessing there must be a downwash component coming off the prop which changes the angle of the air going into this intake.

BTW the genius behind this cowl is Paulo Iscold, a Brazillian who was also partly responsible for the CEA308 world record plane I posted about way back in November 2012.

787 nacelle with sawtooth edge

Bonhomme cowl underneath. NACA ducts for oil coolers and sawtooth edged outlet.

Interchangeable Inlet. Note the tiny gap between spinner and cowl!

Very long spinner and upward angled air intake for the injectors.



Tuesday, 17 March 2015

Week 188 - Engine, firewall prep and upholstery prep

Hours to date: 1705.5

My neighbour and fellow plane mad friend Kelvin has very kindly lent me his engine stand, so I was able to get the engine on the airframe for the first time.

The engine stand is a little over spec for my needs - it will take 2 tons! The UL without any accessories is only about 60kg.

I took my time making sure the straps lifting the engine were in the correct place - ie: under the barrels only and not on any fins. 

After that was on I spent the rest of the next day figuring out where everything will go on the firewall and ordering fittings for mounting these items.

I've figured out what angle and length the exhaust pipe will be. I used my prop angle spirit level protractor for this task. Transferring the level to the end of the muffler with an angle line for the welder to follow. I'm now ready to get our local precision engineering firm to get going on all the welding.

While doing this I noticed that the exhaust header on cylinder number 4 was touching the pushrod tube. Not good. The others all have about 5mm clearance but I couldn't even get a feeler gauge in the space on number 4 as it was touching. So this will have to be fixed by the UL Power factory - most likely with a replacement exhaust part methinks.

I spent last night cutting out the memory foam for the upholstery. I'll be getting all this up to the firm doing the work early next week. Auto Trim in Leicester have a bit of experience with aviation seats already so I think I'll be in safe hands here.

So the engine will come off again this weekend and I'll hopefully start drilling holes in the firewall for all the accessories.

Thigh covers in place.

Trying the chute out for size - all fits good.

Chute pushes me forward a bit which is a good thing for head clearance to the canopy

Kelvin's engine stand. Mighty 2 ton beast!

Easy does it...

Engine on for the first time.

Front view

Side view

Exhaust header on number 4 too close to pushrod tube

Figuring out what angle the exhaust should go at.

Oil-air separator position and one of the oil cooler lines trial fit.

Memory foam cut for the seat.

Memory foam cut for the headrest.

Wednesday, 11 March 2015

Week 187 - ECU, painting, Oil Cooler and Parachute

Hours to date: 1691.75

The parachute arrived last night. A lovely bit of kit it is too - lets hope I never have to use it.

I've made some stand offs out of ali tube for the Regulator/Rectifier cooling flange. These hold the flange about 10mm above the RR and allow the cooling air to pass over the fins and out the sides. 

The ECU is now installed with it's cover. I've done a bit of work to the cockpit loom as you'll see below. Better to do this on the bench than in the plane. The ground lead is a bit fragile so I cut it down and have used a butt splicer and normal 14 gauge wire to extend this as it was a bit short anyway.

The ECU must be kept cool and free of vibration and moisture. Although most people put the ECU on the rear of the firewall I don't think this is the best place as there must be quite a bit of heat soak through the firewall and some vibration. You will see below that I've mounted the ECU with some rubber washers underneath to lift it clear of the safety cell. This will allow air to flow around it more and also help stop vibrations reaching it.

I've painted the headrest and thigh covers so the seat is all ready to go to the upholsterers now. I just have to figure out a way to attach the leather cover to the seat and put a brief together for them so they know what to do.

The oil cooler ducts are now fixed on with Loctite on the screws and they seal very well with the foam insulation I put on. Only a little bit of high temp RTV was needed on one side.

The engine mount is all ready to be welded now with it's 5mm gap. I've got to sort out the muffler as I have ordered a blank version as I want to have the exhaust exit directly rearwards (with the relative airflow) and this will need to be welded on too. I want to wait until I have everything to be welded and get it all done in one go.

Now I've got the ECU in I can get cracking on all the other wiring and the top panel can go in now.

Rectifier Regulator cooling flange with ali stand offs.

Cockpit ECU wiring loom with ground lead strengthened up

Cockpit ECU loom (fuel pump relay is the black box at the bottom)

ECU and it's cover in place. Engine loom will be added after the engine is on it's mount.

Headrest painted

Thigh covers painted

Parachute. Spekon RE-5L - made in Germany.
Oil cooler ducts are on for good now.

Thursday, 5 March 2015

Week 186 - Engine Mount, ECU cover, RR Cooling Flange and Oil Air separator mod

Hours to date: 1680.0

As you'll see below the engine mount needs modifying.

This is because UL Power changed the Alternator fan securing method (6 months after I bought the mount from Pete). This was due to the previous attaching method failing in flight. Pete was over the Swiss Alps when this happened and was lucky that an airfield was directly below him. A bit scary as he said the cockpit was filling with smoke and he was contemplating 'hitting the silk'.

The fan is now bolted in place with a series of Allen head cap screws.
After about 3 hours work I had the offending cross brace cut off and the other two tubes cut down and shaped to fit.

After fitting to the back of the engine and tightening up the mount rubbers to the specified 45mm distance the clearance was just 3mm. This is too small for me so I will do some more work to make it 5mm.

When I was at Pete's the other weekend he showed me the Oil Air separator mod that the does. I'm going to copy him here. Replacing the push on fitting with a weld on -10 male end. It is probably overkill at the push on end but it's the other end of that breather hose that is important. Pete says that he used to run that hose all the way to exit at the back of the aircraft (the same setup as most other aerobatic aircraft) but this long tube resulted in a lot of oil building up in the hose and that caused a pressure build up in the crankcase resulting in an engine stoppage. The solution is to plumb this line into the exhaust pipe. Any oil therefore gets burnt up. The pipe is very short and no pressure build up results. So I'll need to get a male -10 steel fitting welded to my exhaust pipe.

Onto the ECU cover - which is now done and ready to install back in. I made a mould out of modelling foam, put that on the ECU and covered the lot in duct tape. 4 layers of carbon - with an extra layer where the bolt holes go did the trick. I strengthened the back by putting a 'strap' of 4 layers of carbon over the end. (see pic). It weighs just 120 grams and is plenty strong enough to protect the ECU cables from a kick by the pilot's feet.

I've also made up a cooling flange for the Rectifier/Regulator. I did this with a block of plywood shaped to fit the top of the R/R, covered the whole lot in duct tape and laid up 4 layers of fiberglass over this. After that was set I cut a 25mm hole in the middle and bonded a PVC pipe to that with flock and 2 layers of glass. I will finish this piece with body filler and paint to make it look less scuzzy.

I've just heard my parachute is on it's way so it should be delivered by early next week.

Mount before cutting cross brace off completely.

3 hours later

Gap is only 3mm - too small - so I will make it out to 5mm.
Mount on back of engine

Oil Air separator mod - weld on male AN fitting

Pete's set up with breather plumbed into the exhaust pipe

Moulds ready for lay up for the ECU cover and Rectifier/Regulator cooling flange.

RR Flange part way through. PVC pipe just about to be bonded to the base.

All done - except for paint for the RR cooling flange.