GA aircraft takeoff power assistance

Question

I havent come across many GA aircraft that have any form of power assist on takeoff, actually none (besides those with temporary power ratings). Anybody know any interesting systems that have ever been used. I havent even heard of NOX being used. I know fighters have had some interesting systems, but what about GA aircraft?

I think if I was going to choose some sort of power assist, it would actually be some sort of hydrogen peroxide motor, due to their extremely high horsepower for their size (you can hold a 2000 hp motor in one hand), immense horsepower potential (some are over 50k hp), and dense fuel (but still competitive weight wise, its just much more concentrated). Pure hydrogen peroxide is also cheaper than avgas ( relative to the amount of power) and can be combined with sugar to create an even more powerful reaction. They use hydrogen peroxide to power the turbopumps on the soyuz rockets because they are immensely powerful for their size and very reliable.

I dont think it would be unreasonable to equip a system that puts out and extra 100 or 150 hp for a few minutes. The engine itself would only add a few pounds to the empty weight. Anybody have any other interesting ideas?

Answer 1

I tend to agree with the other answerers so I wont restate the reasons. But, I did find this to be a very interesting question and very worthy of discussion. Out of the box thinking is the only thing that has ever changed the world.

Answer 2

I can see three reasons not to do it.

First, as noted, most GA aircraft have plenty of power for the performance they have to achieve.  If there is any correction needed, I would say it would come in the form of superchargers for existing fuel-injected engines, as high altitude performance is the weakest area in most GA single-engine aircraft.

Second, any thrust augmentation system would have to be expensive--probably beyond the reach of the average light plane owner.

Third, there are structural considerations.  Strengthening the airframe would add weight which would be a penalty once the aircraft is airborne.

If any correction is needed I would suggest the better approach would be more power, controllable pitch propellers, and possibly wing geometry corrections such as flaps.  All of these cost money, which could be a huge problem for a private aircraft owner.

Answer 3

I don't know, but GA aircraft usually don't need takeoff assistance, considering that they fly quite slowly compared to the larger commercial aircraft.

For example, my Cessna-172 clears 50 feet in altitute in 2000 ft, with a ground roll around 1000 ft.

But, there are something called JATOs or RATOs, which stand for Jet/Rocket assisted Take-Offs. They're basically like what you just said earlier, rockets attatched to the aircraft to give it some power.

However, I doubt the GA aircraft are built to handle these loads.

Now, remenber that most GA aircraft engines are very similar to gasoline engines, so anything that the formula one racers use, you may be able to use as well.

-After all, advanced piston engine development started with the planes, not the race cars.

Some WWII aircraft had on the order of 2000 hp, and this was back in the 1940s...

Answer 4

The SPAY and TAY eng are over powered for the GA acft and therefore don't need a JATO. From what I was told at Andrews AFB for the army  that the GA acft can fly, land or take-off with one eng with power to spair.

If there was a JATO installed it would be cost ineffective to do for a small amount of acft at GA

Answer 5

Water and glycol injection have been used. A good example is the Beech 99 turboprop that uses such a system for more power in hot weather and / or high altitude takeoffs.

The problem with NOX is that it would likely drive engine temperatures too high, or otherwise create more power than the components are stressed to handle. Most aircraft operate near maximum cylinder head temps, turbine temps, egt temps, max rpm etc during takeoff. Adding extra combustibles only aggravates the situation.

One problem with turning your hydrogen peroxide motor into a useful auxiliary powerplant for an aircraft is turning the power into useful thrust, and the components that could do that and stand the strain would be quite hefty. Then there is the problem of where to put it on the aircraft, and whether it would cause more drag than it is worth once shut down. Then there are the structural considerations of mounting such a device. The structure it is attached to must be built to withstand the stress and strain, as is the structure that component is attached to, etc. This adds lots of weight and complicates design.

Universal Law of engineering - you don't get something for nothing. Everything involves a compromise. The law of diminishing returns is one of the bigger limitations. For instance, why don't they put 8 turbofans on a 747 instead of 4? More weight, more fuel required, more structural improvements, more weight, more drag, etc etc etc.

If what you suggest were practical, someone would already have introduced it. THere are some good books on practical aircraft design and design limitations that are presented in laymens terms (and not pure analytical math). I suggest that you read a few, then start thinking up a new invention. I'm glad that you are at least THINKING creatively. Many people seem to lack that capacity.

Answer 6

Good idea in principle, however I suspect no GA aircraft would stand it.  I suspect you'll find the rocket would indeed take off, but leave the pilot sitting in the remains of the aircraft on the ground.

Do you remember some years ago that bloke in the US who strapped a "small" rocket to his car and launched himself down a long straight road?  They found him embedded in a cliff, the brakes, wheels and everything had melted and the rocket had fired him straight into granite . . .