Thrust vs turbine size
 

Ok I got a quick question.

P80 at 21 pounds of thrust vs smaller merlin 90k at 21 pounds of thrust

While the merlin is lighter

I was thinking of edf were you can make a 110mm fan mwke the same thrust as a 127mm fan but the 127mm fan makes more thrust through its range due to larger fan size

So my p80 looks like it has a bigger compresor fan so if weight is not a issue what would make you choose one over the other?

Merlin 90 without question, it looks tiny compared to the p80, I had one ran flawless..I would love to get my hands on another one. Mine was turned up to 154k RPM 22+ pounds
out of that little beast.

Well that is why I asked the question. I currently have a Merlin 90 that I got from one of my boys as he has wiped his hands of it

He got it for a skymaster viper but every time he tried to fly it it would melt his air and fuel lines in front of the motor with a fireball

Hey told me that he has sent it back to Dreamworks 2 times and was told it was good to go

After his last fire last month I convenced him to just get a Kingtec 100 and has since put 2 flights on his viper

That does not sound right at all, sounds like an install or operator error. The compressor side of the motor(front) does not get hot enough to melt anything. Jets Munt turbines are top notch, and if something is not right Todd and Gaspar will make sure its right.

I don't know about the Merlin but all my small wrens make all the power in the last 20% of the RPM range. My P80 still made a good amount of thrust at mid RPM,s. So I would assume that a smaller turbine spinning at a higher RPM would do the same

Dieselman1220,

How do you know your turbine is putting 22+ LBS out at max RPM? Do you have a test stand or some type of scale that you use to verify the specs? I heard the German and some other European built turbines use a calculation based on 15*C temp, humidity, density altitude etc and readjust the actual output to their stated output. I have seen some YouTube video's, of some guys in Oklahoma testing their KingTech's in like 90* weather. They had a digital scale set up on a cool stand they built and video'd the actual thrust the KingTech's were producing, and it was over the stated thrust on the website. I hear Merlin's are good turbines but I'm curious if they calculate their thrust like the other German turbines.



Ghostrider Out!!

To answer the Ops original question.

"So my p80 looks like it has a bigger compresor fan so if weight is not a issue what would make you choose one over the other?"

The P 80 is a fairly old design nowadays. Newer design turbines such as the Merlin M 90 put out more power for a given wheel size then the older models. This is due to better efficiencies of newer designs, and simply running higher shaft speeds..

So, If weight is not an issue for you, then the only advantage of the smaller turbine,,,, is that it is smaller. Fuel efficiency favours the P80 slightly (according to manufacturers data).. There may be an argument that higher shaft speeds increase bearing wear of the smaller engine, but both Jetcat and Merlin recommend the same bearing service intervals…

I have a Jets Munt VT 80 and an M 140.. Both are very reliable and very powerful.. I agree with Dieselman. If you are having trouble running the M90, it is likely a set up error. Gaspers equipment is very good..

Hope that helps..

Thanks great post yes this is what I was looking for

When I get back from Army training this Saturday im hopeing to put this motor on a test stand and run her up

So dose anyone have one of these 90k running sweet that would not mind if I gave them a call after 6 on the weekend? I got a feeling the issue may be from his messing with some of the setting

Thanks Mike. 832 857 6931