New engine

[svenolivier]

I have now done about 30 hours with the Aerovee and except only for a high oil pressure problem, which is now resolved, she is flying beautifully

Thank you all for the help and assistance (but i am quite sure i will have many more queries as i go on)

kind regards

Sven

[svenolivier]

Hi Neil and Paul

I trust this email finds both of you well. I am slowly beginning to look at an inverted system for the Tipsy.

1. My very biggest concern (out of many others) is the nature of the work required on the engine - Neil stated elsewhere that "The oil pickup needs modifying while the engine is split to move the pump inlet to the side/front of the engine. The oil is then fed to the pump via an external changeover valve to supply either from the sump or the rocker covers. The engine breather system will also need modifying."

The Aerovee has the oil pump below the prop hub, and the present system has the oil cooler connected to the oil pump in and out lets. The fuel is warmed by oil from the top of the engine, as in the original design.

If I understand correctly, the external changeover valve

a. at the top connects to the inverted pickup - can this be where the existing engine pumps oil to and from housing which warms the fuel? Or do i need to tap into the engine casing?

b. at the middle connection goes to the oil pump (how does that interact with the present inflow from the cooler?)

c. at the bottom goes to the sump (this I assume is the oil sump plate)

2. Then I have to fit the oil catcher and provide for it to accept oil from the breather and route it back oil to the sump (it has a valve for inverted flight). This is an essential further step for me, even if i dont' do step one - there is too much oil from aero's at the moment.

3. Fit a slide carburettor -

4. Fit a flop tube and a aerobatic fuel cap (i will have to seal of the vent for measuring fuel).

5. Fit new seat harness

Should you guys have any advice / comments i gladly receive those.

Kind regards

Sven

[Paul1954]

Sven, greeting. Well done with getting your Nipper back flying.

Four area to concern yourself with if you want to think about when turning your existing VW into one with an inverted fuel and oil system:
• Fuel system - engine
• Oil system - engine
• Fuel supply - airframe
• Weight.

You may not think the last one matters, but add up all the extra bibs and bobs, put in fuel for aeros, add your own clothed weight, and ask yourself; will my aircraft be within the permitted weight and c of g limits for aeros?

I suggest that there is plenty of information available within the International Aerobatic Club’s technical archives to postulate a solutions to your questions. https://www.iac.org/technical-tips

Posted below are images of the engine that resulted from hundreds of hours of testing the Acro VW engine on an inverted rig. It is the gold standard to beat; it worked, it fitted under an improved streamline cowling, and it was lightweight. https://acro.co.uk/index.htm

If you review a previous thread regarding the existing fuel tank and modifications that will help too.

Forgive me not being more helpful, but these events happened 30+ years ago, and my recall is not what it once was.

Paul

[Paul1954]

More images…

[svenolivier]

Dear Paul

A short note to say thank you so much for all the information and leads. I appreciate it beyond words. The links are most useful - i have joined IAC and EAA
I shall digest and plot ahead.

Many thanks

Sven

[Paul1954]

Sven. You are welcome.

Have a look through the tech gen, particularly the early Pitts articles. You will find a lot of similarities to the system used for the Acro. Aircraft Spruce used to carry useful generic parts that could be of use or adapted.

As for the flop tube, it was a piece of fairly rigid fuel hose (suitable for immersing in fuel) with a connector to fit the fuel tank fitting at one end and a brass mass at the other. The brass lump was machined to connect into the tube, and a hole was drilled some way through the lump. A gauze filter covered additional holes in the lump’s circumference that allowed fuel to be drawn through to the tube.

Note the modified rocker covers - that’s where the oil goes when the aircraft is inverted.

[Neil Spooner]

Hi Sven,
I am currently away from home so using a horrible iPhone to type...slow & tedious, plus I don’t have access to all the photos. Anyway:
Oil systems:
Oil Feed:
I have found a supplier for a front cover for the oil pump, which is actually designed for an external oil feed to a cooler, but, if the intake of the oil pump (pump removed) were blocked off and the front cover reversed so that it now provides an inlet to the pump then that is now your oil feed inlet sorted, no need to modify the crankcase.
The oil change over valve has three ports:
Top which goes to the top of the engine case, such as where the oil filler is located, or a T that goes to the top of the rocker covers as per B Smith.
Middle goes to the inlet port of the oil pump.
Bottom which goes to the bottom of the conventional sump.

Breather:
You will need to create a “change over” breather box. Difficult to describe but essentially allows the engine crankcase to breathe when inverted without dumping the oil overboard. More later.

Fuel systems:
Flop tube:
There is available submersible fuel hose that is designed to live inside of a fuel tank. You will fit a clunk weight to one end, the other to a tank fitting at the middle (vertically and horizontally) of the front of the fuel tank. This then goes to a fuel selector for “Sump or Flop”
Carburettor:
Sadly Ellison no longer make the EFS2, second hand ones do become available but are very rare. So, regrettably the only other unit available is the Rotec. I have had terrible problems with Rotec, so will have nothing to do with them. But as it stands they are the only provider of a slide carbs. The Aerovee & Revflow units seem to very difficult to set up, use and maintain.

Seat belt:
A good 4 point belt with a backup lap strap is a must. The shoulder harness needs to go to the cross tube just behind the seat to provide torso support. Not ideal but the only viable solution. (This setup has been thoroughly tested during my forced landing, & restrained me very well).

All articles in the aircraft need to be restrained for inverted flight to -4g.

As Paul says, you need to work hard on the weight of all of this, it’s all pointless if the a/c is too heavy for aeros.

Personally I would have trouble owning/operating my own a/c if it wasn’t able to fly inverted, it really does provide freedom from terrestrial life.

More later....

Best wishes.

Neil

[Neil Spooner]

....the last picture Paul posted....what a young Barry Smith !

[Paul1954]

Probably take about 1990. Oh what happy days they were.

[svenolivier]

Hi Paul and Niel, many thanks for all the VERY useful information. I am digesting and formulating a plan. I report back soon.
Many thanks again
Sven

[svenolivier]

Hi Niel and Paul

I am making slow progress - i appended some notes to Niel's comments

Hi Sven,
I am currently away from home so using a horrible iPhone to type...slow & tedious, plus I don’t have access to all the photos. Anyway:
Oil systems:
Oil Feed:
I have found a supplier for a front cover for the oil pump, which is actually designed for an external oil feed to a cooler, but, if the intake of the oil pump (pump removed) were blocked off and the front cover reversed so that it now provides an inlet to the pump then that is now your oil feed inlet sorted, no need to modify the crankcase.
Could you, once you are back, furnish particulars of the supplier
The oil change over valve has three ports: can i use the Raven System oil valve?https://www.aircraftspruce.com/catalog/eppages/basicinverted.php
Top which goes to the top of the engine case, such as where the oil filler is located, can i use the inlet at the top of case where the cooler may reside, but which is used in the Tipsy to supply oil to and from the heater around the fuel manifold? or a T that goes to the top of the rocker covers as per B Smith.
Middle goes to the inlet port of the oil pump. the Aerovee has an oilpump at the front which i presently use for the oil cooler - can i simply use a T from the oil change over valve?
Bottom which goes to the bottom of the conventional sump.

Breather:
You will need to create a “change over” breather box. Difficult to describe but essentially allows the engine crankcase to breathe when inverted without dumping the oil overboard. More later. can i use the Raven oil separator? space seems to be a problem

Fuel systems:
Flop tube:
There is available submersible fuel hose that is designed to live inside of a fuel tank. You will fit a clunk weight to one end, the other to a tank fitting at the middle (vertically and horizontally) of the front of the fuel tank. This then goes to a fuel selector for “Sump or Flop”i think i can source all this from aircraft spruce
Carburettor:i have sourced an Aerovee
Sadly Ellison no longer make the EFS2, second hand ones do become available but are very rare. So, regrettably the only other unit available is the Rotec. I have had terrible problems with Rotec, so will have nothing to do with them. But as it stands they are the only provider of a slide carbs. The Aerovee & Revflow units seem to very difficult to set up, use and maintain.

Seat belt:
A good 4 point belt with a backup lap strap is a must. The shoulder harness needs to go to the cross tube just behind the seat to provide torso support. Not ideal but the only viable solution. (This setup has been thoroughly tested during my forced landing, & restrained me very well).

All articles in the aircraft need to be restrained for inverted flight to -4g.

As Paul says, you need to work hard on the weight of all of this, it’s all pointless if the a/c is too heavy for aeros.

Personally I would have trouble owning/operating my own a/c if it wasn’t able to fly inverted, it really does provide freedom from terrestrial life.

More later....

Best wishes.

Neil

[Neil Spooner]

Front cover for oil pump: https://www.ebay.co.uk/itm/303813309820 ... Swsttf2itL
The Raven system is fine, you will only need the oil change over valve.

The ports on the top of the engine you refer to are part of the pressurised system. The easiest option for you is to add a pipe to the top of each rocker cover, link the two via a T piece which will supply oil whilst inverted. If you remove the cylinder heads for maintenance take the opportunity to fit "windage" push rod tubes, but the wrong way around, so that the extended end is in the rocker cover. This will retain more oil in the heads for when you roll inverted.

https://www.heritagepartscentre.com/uk/ ... steel.html The only issue with this is if you do very slow rolls, rolling circles, or 4 point rolls you will suffer momentary oil pressure loss. The system I use is far more complex but will provide oil pressure all the time.

If the Aerovee oil pump already has the same type of cover as I have given a link for then you will need to look for a machine shop that will make one with a port for inlet and outlet (double ended). This is not a difficult solution, and saves having to split the engine case to modify it.

You will not have room for the Raven breather system. I could make you one and send it.

I don't think LAS supply that kind of hose. Try this: https://www.fuelpumpsonline.co.uk/cohli ... 5494-p.asp

The Aerovee "Aeroinjector" is available, but personally I have not used one. I have a second hand one that you could buy/try.

Regards

Neil

[Neil Spooner]

Some photos of top side.

[Neil Spooner]

Lower engine.

[svenolivier]

Dear Niel and Paul

Complex
I am putting together my shopping list.
Niel, am dead sure to fit the breather system - i am just getting to much oil on the outside after every flight
So may i ask if you could please take you up on the offer for a breather system?
I have many more questions but need to digest more before asking.
Many thanks from a wintry Cape Town

regards

Sven