I hope im in the right catagory for this problem i have.
Ive got a evolution 100 engine in a T28,scratch built.
The engine calls for a 14x6 prop.
In order to use this engine in this airplane i can only use a 12"prop,ground clearence thing.
I would like to use a two bladder,they are cheaper than a three bladder
What pitch should i use and are they avalable?
Thanks in adavance.
Take care
Frank

You have to check the minimum prop size for that engine. I think you may run into problems with a 12" prop. It seems like it may be too small and you will overspeed the engine which could lead to failure. You may end up having to bite the bullet and just get a 3 blade prop. Also I tried checking the evolution website to see your engine and all I saw was the 1.20NX, is that the engine you have??

Yes it is the same engine.
I googled apc and they have props that are 12x10,s etc.
Im wondering if a 3 blade in a certain pitch and a 2 blade with a pitch to match the 3 blade.
In other words how would i compare the 2 props,hope you understand what im taking about.
Tc
Frank

Ok, well the website shows a 14x6 being the smallest 2 blade prop you would want to use. The only thing that I could think of would be to find a 12" prop that will stay below the max RPMs for that engine. So in that case Im not sure what the max pitch is for a 12" prop. But by doing this you will probably fly the plane alot faster than it should go and vertical may not be good. Why not get a taller landing gear or use a smaller engine if you have one? Could you post pics of the plane? How heavy is the plane?

i cant use a longer nose gear.
i tried a 80 4 stroke and it didnt have enough omf.
hang in there and ill sent some pix and you can see why.
i think a 12x10 apc 2 blade would do the trick.
what do you think.
tc
frank

Its hard to tell anything from that pic, but I see that you have a tricycle gear setup. Post more pics, but couldnt you convert it to a tail dragger. And Im not sure if a 12x10 will do it or not, you will just have to try it I guess.

T28,s wernt tail dragers.
so i guess ill have to try the 12x10 and see what happens.
hope the snow stops so i can try it.
tc
frank

I thought you might say that about the tail dragger idea, lol. Well I guess best thing to do is experiment.

Frank, another thing you should take into consideration is the weight of our plane and wing profile vs thrust. Since thrust is a direct function of your prop's diameter you don't want to be on the short end of the stick for your plane.

This is especially important if your model has a thin wing and fairly high wing loading (Needs thrust + speed) which in not unusual for a WW2 vintage scale bird.

You can download ThrustHP to give it a sanity check.. In my diesel experiments I tried about a dozen props on one engine and the results did vary from not wanting to leave the ground to flying pretty well..

Good luck, it sounds like a fun project.

Howdy
Thank you for the info,ill give it a try and see what happens.
Thanks again.
Tc
Frank