"Create a technological backlog": the developer of an aviation "hybrid" - about the advantages of a new engine from MAI

- Projects of aviation hybrid power plants (HPU) have become a kind of technological trend all over the world.

Only in Russia in this segment are such titans as the Central Institute of Aviation Motors.

Baranov (CIAM) and the United Engine Corporation (UEC).

What is the specificity of the MAI project?

- Unlike other enterprises, the design team of the 203rd department creates a hybrid power plant for unmanned aircraft and light manned aircraft.

This is our niche and here, as I think, we do not compete with other domestic developers.

In addition, the MAI project involves the use of an internal combustion engine (ICE) in the GSU, and not a classic aircraft gas turbine engine.

The idea to combine two power units - an electric motor and an internal combustion engine with a common propeller drive - came to me in the process of developing and bench testing the components of an electric power plant (EPS) for an experimental single-seat electric aircraft.

The main idea of ​​such a product is to use a piston engine with power only for horizontal flight, and to provide the necessary increase in thrust for takeoff and climb at the expense of electrical energy.

We already have a flying demonstrator of an electric aircraft in our assets, in which part of the tasks of developing a HCS has been solved.

- When did the work on the GSU begin?

- Work on a hybrid power plant started at the department in May 2021 with the support of acting.

Vice-Rector for Research, Doctor of Technical Sciences, Professor Yuri Ravikovich.

In November 2021, our project won first place at the XIII All-Russian Intersectoral Competition "Youth and the Future of Aviation and Cosmonautics" in the category "Aircraft, Rocket Engines and Power Plants".

• MAI design engineers Dmitry Borisov (left) and Kirill Balyasny (right)

• © Personal archive of MAI design engineer Kirill Balyasny

In December, the GSU project was presented to the Rector of the Moscow Aviation Institute, Doctor of Technical Sciences Mikhail Pogosyan.

As a result, a recommendation was received to create a line of aviation "hybrids" of various capacities for aircraft of different classes.

In addition to me, design engineer Dmitry Borisov and lead engineer Alexei Sychev are working on the GSU.

We also try to involve students in the work.

For them, this is a unique opportunity to take part in the design and construction of aircraft, master modern production equipment, learn 3D modeling and drafting design documentation.

— What practical effect do you plan to achieve?

- There are several schemes of hybrid power plants, the most common is the use of a piston or gas turbine engine in conjunction with a generator.

A traditional power unit stores energy in a battery that is connected to an electric motor with a propeller.

As I said, we use a common drive of the internal combustion engine and electric motor to the propeller.

This allows you to make the hybrid power plant more compact and lightweight.

Our GSU will increase the flight duration of aircraft (compared to purely electric ones), increase power in takeoff mode, and also reduce the cost of the power plant compared to internal combustion engines of similar power.

In our "hybrid" in takeoff mode, an electric motor will be connected to the operation of the internal combustion engine and additionally increase the power of the GSU.

In cruising flight, only the internal combustion engine will work, and the electric motor in recovery mode (returning energy for further use. -

) will be able to charge a small buffer battery.

Also, the electric motor in case of failure of the internal combustion engine should help the aircraft fly to the landing site.

- Modern demonstrators (prototypes) of the GSU still have many shortcomings.

One of them is excessive weight and size properties.

After all, the aircraft should, in fact, take to the air with two motors instead of one and still carry a battery.

- Yes, this is true, but intensive work is underway all over the world to reduce the weight and size of the GSU.

Mathematical calculations and practical tests convincingly prove that the main advantage of aviation "hybrids" lies in the fact that they give a gain in flight range and duration.

As a result, savings in the cost of operating the aircraft are achieved, and harmful emissions are reduced.

So, if a modern single-seat aircraft, equipped with a power plant and a battery, provides a flight for about 25 minutes, then the "hybrid" we are creating with the same weight already allows you to stay in the air for more than an hour.

Of course, modern GSUs are far from ideal.

Significant progress in this area is also related to how efficiently a classic engine will act as a generator and how much energy a battery pack can hold, which at the same time must remain compact and relatively light.

• Specifications GSU MAI

• © Personal archive of MAI design engineer Kirill Balyasny

Naturally, all these issues are being worked out by the staff of the 203rd department of the MAI.

At the current stage, it is important to complete the design and assemble the HSU demonstrator, and then determine the directions for improving the product.

In the future, we expect to use batteries weighing 6-7 kg.

- What motor will be in the GSU as an internal combustion engine?

On what parameters did you choose the ICE?

- For the experimental work, a gasoline two-stroke engine RMZ-500 with a capacity of 50 liters was purchased.

from.

This is a domestic analogue of the Austrian power unit ROTAX-503.

It is used on paragliders, airboats and snowmobiles.

RMZ-500 is a reliable, economical and affordable engine that can develop the necessary thrust and give the carrier the ability to maneuver.

- It is no secret that Russia is experiencing certain difficulties in equipping UAVs with its own power plants.

Will there be many imported units and systems in the GSU

- In the manufacture of prototypes, it is normal practice to widely use components available on the market, because the first task for designers is to check the viability and adequacy of the adopted technical solutions.

I will not hide the fact that our GSU has foreign components.

This is an electric motor controller, a variety of sensors, a battery cell and more.

The share of imported units and systems in the product will be about 30%.

But in the future, it is quite possible for many foreign-made components to be replaced by domestic counterparts.

The share of Russian elements can be increased to 85-90%.

- Do you have an idea on what devices you will mount the GSU?

- I want to remind you that modern aircraft engines are often not developed for specific carriers.

In our case, we have an understanding that the "hybrid", which is being created at the Moscow Aviation Institute, will be in demand in amateur aviation, that is, for installation on single and double-seat aircraft.

This market is developing quite actively, including in our country.

For example, in Russia, single-seat aircraft with a takeoff weight of less than 115 kg can fly completely freely.

Many people who are passionate about aviation take advantage of this opportunity.

It will also be possible to equip aircraft-type drones with a take-off weight of up to 400-600 kg with our product.

Now in Russia there are strict legal restrictions on UAV flights.

Devices from 250 g to 30 kg must be registered, and they can fly far from everywhere.

Flights of heavier drones are, in fact, prohibited.

However, many experts are confident that drones will certainly be widely used in the Russian Federation for commercial and other purposes.

In Russia, zones are being created where the mass use of UAVs, including heavy ones, is being tested.

For example, in the Tomsk region, it is planned to use drones weighing more than 30 kg for the delivery of heavy loads (from 0.1 kg to 1500 kg), aerial photography and agricultural work.

According to the Ministry of Economic Development of the Russian Federation, before the end of this year, our country plans to launch several so-called experimental legal regimes (EPR) to test the possibilities of cargo and passenger transportation using drones.

The widespread use of civilian drones will certainly become a reality, and, naturally, UAVs will need reliable and efficient engines.

We can say that the staff of the 203rd department of the MAI is working ahead of the curve.

Now it is important to create a technological backlog, which will then allow us to improve and produce a line of “hybrids” to meet the needs of customers.

- At what stage is the implementation of the GSU project and when is it planned to start flight tests

“Now the last stage of the assembly of the “hybrid” is being completed, a ground test bench has already been created for its testing, the electric motor is being tested, which has become more powerful, the gearbox is practically manufactured.

Testing will begin soon.

During them, the control system will be tested first (both separately and as part of the GSM).

It must ensure the synchronous operation of the internal combustion engine and the electric motor.

Then power bench tests of the "hybrid" will start.

In the fall of 2022, we plan to conduct flight tests on a demonstrator aircraft.

• Aviation GSU MAI Demonstrator

• © Personal archive of MAI design engineer Kirill Balyasny

In addition to the HSU, a distributed power plant is being created - these are several small electric motors with propellers that are located along the leading edge of the wing and create additional lift.

At the same time, their food is provided by the march GSU.

Such a product, from our point of view, will be required for aircraft with short takeoff and landing.

According to the calculations we made, our engine will be comparable in terms of specific weight and power to the Austrian Rotax 912 UL engine, but will be almost three times cheaper.

We are currently negotiating with potential customers interested in our project.

We evaluate their requirements and our ability to establish the production of "hybrids".