Test running engine without wings

[jim]

Originally Posted by rvbuilder2002

Thanks. I didn't notice.
That would make a difference. I hope no one ever considers doing this with a lycoming.

Hi Scott,

Just out of curiosity, because I don't know the answer, why is it bad to run the engine without the prop? Do you need the weight (flywheel effect?) of the prop to prevent damage to the engine? Or is it a cooling issue, or some other reason(s)? What kind of damage could happen? This is a sincere question, I would like to know what the reason(s) is/are, to not operate the engine without a prop. Please excuse my ignorance on this topic, and I do NOT intend to try this when I get my engine, just curious.

Thanks,

[gmcjetpilot]

Per one of Rod Machado's amusing stories (if you know him you are laughing already), put a fuel can under the cowl or in the plane, just a little and with out the wings, taxi out to the runway. Ask the tower for take off. It only works if the tower is looking. Can you imagine the look on the tower jockeys face. When the ask you want to takeoff assure them, Yep! Were going to blast off into the wild blue.

[MichRV10]

Jim go to your PM

[pierre smith]

Originally Posted by jim

Hi Scott,

Just out of curiosity, because I don't know the answer, why is it bad to run the engine without the prop? Thanks,

Jim,
There were many Lycoming ground power units running without props and helicopters with Lycs don't have a prop. The Hughes 269 starts without a prop and then the clutch/belts are gradually engaged and the rotor starts spinning. Both engines in these scenarios have fans though, for cooling.

The aluminum Lyc flywheel probably doesn't have enough mass or inertia to get/keep it running but it may. You'll need some sort of fan laying horizontally over the engine as I've seen some test cells do.

Ya gotta admit, starting with a prop is just so much easier.

Regards,

[jim]

Hi Pierre,

Thanks for the reply. I am not planning on trying this, I just was not sure why you should or should not do it. It sounds like it would be more complicated without a prop. I hadn't thought of the helicopters, I think the Canadian Rotors Bell look-a-like uses a lycoming with a clutch set up similar to what you mentioned. Those look sweet!

Thanks,

[rvbuilder2002]

Originally Posted by jim

Hi Scott,

Just out of curiosity, because I don't know the answer, why is it bad to run the engine without the prop? Do you need the weight (flywheel effect?) of the prop to prevent damage to the engine? Or is it a cooling issue, or some other reason(s)? What kind of damage could happen? This is a sincere question, I would like to know what the reason(s) is/are, to not operate the engine without a prop. Please excuse my ignorance on this topic, and I do NOT intend to try this when I get my engine, just curious.

Thanks,

It is for all the reasons you mentioned.

There is absolutely no load (torque or inertial) load on the engine without a propeller.
An auto engine has a heavy flywheel to help it idle smoothly and more slowly than it could otherwise. This flywheel also has inertial resistance to not allow the engine to rev up too quickly even if the transmission is out of gear or in park.
A propeller is an airplane engines flywheel.
It resists the engine from accelerating too quickly by its inertial load and aerodynamic load. With out a propeller the engine can change RPM almost instantly. This is very bad for the engine. Any idea what happens if a builder accidentally hooks his throttle up backwards and he starts without a prop installed (this does happen, by the way)? The engine is toast in about 1 second. If a prop. is installed and he has at least tied the airplane down, the worst thing that happens is a bit of a fright and he shuts it down right away.

What Pierre wrote is true. Many helicopters do start with the rotors decoupled, but they still have some resistance on the engine from a big cooling fan (which also is cooling the engine as soon as it starts. You don't have this if you are starting without a prop. installed). It is also a proven installation, not a very first engine start.

Doing an engine start before the airplane is completed and nearly ready for the first flight is of no technical value (with or without a prop installed).
There are so many thing that can go wrong, it just makes sense to wait.
- Just my opinion based on 18 years of experience building RV's-

[Bill Dicus]

Hope I'm not hijacking the thread, but what is a good preservative to spray in the cylinders? I would guess any oil would work - but what's best? Thanks for any opinions! Bill

[GJHeck]

Kahuna,

What did you use to tie the MLG to the fuselage instead of the wing spar? Do you have a Picture? I'm at the stage of putting my MLG on and would like to pull the wings off and complete the project. I pretty much know what I would like to do but am open to other ideas.......Thanks!!!

[Low Pass]

Originally Posted by Bill Dicus

Hope I'm not hijacking the thread, but what is a good preservative to spray in the cylinders? I would guess any oil would work - but what's best? Thanks for any opinions! Bill

LPS-2 or LPS-3 (heavier film).

[Kahuna]

Originally Posted by GJHeck

Kahuna,

What did you use to tie the MLG to the fuselage instead of the wing spar? Do you have a Picture? I'm at the stage of putting my MLG on and would like to pull the wings off and complete the project. I pretty much know what I would like to do but am open to other ideas.......Thanks!!!

In the old days, we had to laminate some wood together the right thickness and stuff it in there. Bolts through the wood held it in.

Its way too long ago to remember. Oh wait... I just found a picture. Wow this stuff is old.