Props4ever

Guys I need bit of your help here. I just got a Fantrainer in a trade and now I seem to have but of delima with this model.

Shroud can only take 9" fan blade or 2, 3 bladed prop on SK50 or OS55 engines!, now my question is: What is the best combination of engine prop/fan blade for my application?

Will appreciate all the help.
Sammy

Mark 5

What size Fantrainer do you have? I scratchbuilt 2 Fantrainers a .25 size and a .10 size both flew great and were fast.My small .10 size fantrainer required a prop with more pitch,but there were no props available in that size so I had to carve my own prop(5x5 three blade pusher which worked quite well. If you can't find a good pusher prop you can cut down a J&Z 11x10 pusher prop, this should be a good starting point.

Props4ever

Mark

This is built from some old kit that I don't know about. It has wingspan of 71" and length of 64". Recommended engine on plans is Webra Speed 50 but no mention of prop type or size.

Shroud's inner diameter is 9-1/4" therefore I'd say 9" would be the biggest prop/fan blade that could be installed on the engine.

Props4ever

Mark

This is built from some old kit that I don't know about. It has wingspan of 71" and length of 64". Recommended engine on plans is Webra Speed 50 but no mention of prop type or size.

Shroud's inner diameter is 9-1/4" therefore I'd say 9" would be the biggest prop/fan blade that could be installed on the engine.

Props4ever

Mark

This is built from some old kit that I don't know about. It has wingspan of 71" and length of 64". Recommended engine on plans is Webra Speed 50 but no mention of prop type or size.

Shroud's inner diameter is 9-1/4" therefore I'd say 9" would be the biggest prop/fan blade that could be installed on the engine.

bob27s

My Feedback: (19)

No problem running a 9x8 or 9x9 on the OS55 - it is not going to self destruct at 16,000 rpm. The SK50 should be ok too, but I have no experience with them.

But its worth noting, if that is a fan trainer, neither of those engines will turn much in the way of rpm. Their carbs and porting are for lower rpm operation (compaired to say a Webra 50, 55 or even a TT 46). Performance of the plane might not match well with the engine combination.

Props4ever

Bob

From what I gather you don't think SK or OS are going to be good speedo types on this preticular model. Then what engine should I look into to get the performance from this model?. I mentioned those as I have them and are new engines. Plus this model is +- 10lbs in weight now with everything installed minus reciever and I'll be flying from grass runway mostly.

Props4ever

Bob

How would Webra 53 or Rossi 53 be for my application with custom made 9X10 or 9X12 Fan at 16,000 rpms?.

freakingfast

My Feedback: (3)

Would I be correct in the assumption that this plane was meant to be powered by a speed 600 motor and you are converting it to glow? If so, keep in mined that you would have a large engine aft and you wont have the large battery forward to offset it. Hopefully you can put the receiver battery far enough in the nose.

Iā€™m also assuming that the glow engine would be oriented the in pusher configuration, which seriously limits prop selection in the 9ā€ diameter range. If you could find an engine that runs clockwise (as viewed from the front) you would have a much better selection.

If you could find such an engine, it would hopefully be of the higher rpm class of engine to make the best of your 9ā€ prop limitation. I like the OS 55 but, even if it could be reversed (crank port timing change), it works at too low an rpm range for your needs.

Props4ever

No sir this not a converted or being converted into glow model. This model is designed to be powered by high speed/rpm 50 size glow engine. I'm looking to get custom fan made as 9" pusher configuration and high pitch.

freakingfast

My Feedback: (3)

Ok.
Well that could cost you. About $100 us for a custom PROP mold and $20 or more per prop and if you gessed the pitch wrong?[X(]
A custom fan? Unless you're rich, forget about it.
I looked at a ducted fan for K&B 100 or 90+ BVM and its only 4.875" in diameter and has an 11 blade count, so you can't remove every other blade(if that idea even has merrit).


Other ideas if you insist on a standard rotation engine:
Apc's 9X6 pusher is too low in pitch
Graupner's 9X7 is too low
Master Airscrew's 9x7 3 blade Pusher is getting closer and would work, but at 9" it is limited to 18,300 RPMs, a strong 45 to 50 class could unload it past this point in the air and its efficiency falls off radically up there.
Master Airscrew's 10X7 3 blade Pusher cut down to 9" would render about 9X8 maybe that could work.

Or, use a heat gun and pitch gage. Tweak any prop to your liking. If done wrong this could be very bad[:@]

Now a thought...... would the prop's loading/efficiency be different in a shroud than a prop in free air?

One last thought, install a ducted fan pusher package inside the shroud.

Good luck!

bob27s

My Feedback: (19)

That question tends to depend on the exhaust system you choose to use. A pipe or tuned exhaust really makes a huge difference.

Rossi 53 or Webra 55 would be fine..... you would probably want less than 9x10 ...... maybe 9x8 or 9x9 props. These you would wante to turn up higher .... closer to 17,000 rpm... although they are just fine anywhere between 15,000 and 17,000.

The OS 55 would probably work ok..... just needs the right prop selection to hit its best performance rpm.

At 10 lbs...... its a lot of airplane.... be patient on the take-off roll.