GB the whole point of my post was the gentleman already had an appropriate engine for his airplane and a darn good engine at that. He was being convinced to go buy new engines unnecessarily after just flying his new airplane likely only a few flights with just one size prop with no other testing at all and on top of this he is just off a trainer.

Whats wrong with that picture?

He needs to experiment with props both the eleven inch and the longer flatter props and decide for himself. Since he spelled out he is looking for more speed then yes I still beleve the 11x7 would be the first that I would try and remember more speed will translate into what folks sometimes perceive as vertical performance. The longer/flatter props may be an improvement as well but my suggestion remains shorter/corser. Definately not the 12x6 on a great aggresively ported *****ie like the .61FX. We are not talking about the old cross ported or loop scavenged .61's.

John

A wall of props should be on every modelers dream agenda if you plan to stay in the hobby/sport/passion, it is so very useful for just these reasons.

Well John, whenever I don't have enough different props to test on my new planes I always go out and buy a couple new engines!! I do it on line though so I don't spend any extra money going across town to Nice to buy some more props, I just hate wasting money and can't stand driving past the strip, all those posters of semi clad women!! Driving past Play it again Sam's also makes my mouth water for one of those wonderful cheese burgers and a beer, then the devel makes me turn around and look at those girls wearing nothing but a smile and a G-string, bad devel, bad!!! Then I just end up with boxes of different props of different sizes and things. I use boxes, my shop is too small to start putting much more stuff on the walls.
If I do buy more props then I have to go flying all weekend and test props to find the one I like, you know how much work that flying stuff is. Who in there right mind would want to spend a weekend flying there planes??
Just sounds like a lot of extra work to me. I think I will vote along with the new engine guys, I think I would pull the engine out of my sand rail and install it in the nose of the plane, 2300ccs should give it the pull and speed wanted. I do see a CG problem but it would save me that drive and money!!
Then again, those are some really good cheese burgers!!!
Gene

Outstanding I like the way you think Hm, one can never have enough engines

Thanks John I will get a 11x7 and see how that does. I also picked up an APC 12x6 at the shop, so well see how testing goes. Might be buying a new radio since I accidently dropped mine and I am not really wanting to take the risk of losing such a good plane.

Jason

what hogflier said is right on. a 75 would really help. doesn't have to be an os engine. there are other 75's that put out almost as much power,for a little less money. ....RON

I'd experiment with higher nitro content fuels, lower pitch props http://www3.towerhobbies.com/cgi-bin...?&I=LXESM8&P=7
and see if you like what you have in the plane already. Problem with changing from OS to an AX or another brand at this point (I do have the same plane, but run a OS 61 SF series on it) is you've cut the cowl for the OS already and another change requires a new cowl or the swiss cheese look, not to mention changing pitts mufflers.

I agree you should just fly it scale and not worry about unlimited vertical on a large wingspan/heavy plane as the chipmunk. Scale plane, scale flying.

Hi!
Seems like the Chipmunk is not that large...a 11x7APC migth work.
If the span is around 150-165cm I would go with either a 12x6 or 13x4 or 13x5 APC.

hey
I got a 12x6 APC and it runs good. I also got a 13x7 and will have to test that prop out.

Hi!
A 13x7 is way too big!
As I said earlier a 13x5 might work.

I'm not sure about the .61FX but I have a magnum ringed .61 and running a mas 11x8 prop I'm pulling 14000 rpm and in a .40 size pony it books!!!

The 13x7 was too much and it didn't perform all that well. I went back to the 12x6 and it seems to good with that one. I will have to find a 12x7 and see what that does.

11x7

Just stuff your pockets with some money and get right out there and buy a big bunch of props and start having fun doing some testing!! Prop/engine/plane combo is a pilot thing and you need to do the testing so you can find the combo that makes you, the pilot happy.
For myself I like a slower plane with as much thrust as I can get, I would be looking at the 12X4 or maybe even some of the odd pitched 3-D props for something even a bit lower in pitch.
One of the nice things about where I fly is the people. If we know someone is doing some prop testing we will take out a bunch of props and we end up with a big pile of them for the guy to test. Saves a bunch of money.
If John says an 11X7 you better have one in your box. I'm sure he has tried them all by now!!!

I am going to get one and try it. Its a Kit plane. Will that have the thrust for vertical?

It will allow the engine to acheve the rpm range that is near optimum while still retaining sufficient pitch to provide a higher level flight speed. It will not provide the optimum for hovering type manuvers if that is what you mean by vertical. For that you would use the longer and flater props most are suggesting here that will limit level speeds.

Now if we make the airplane faster then we pull into a vertical at speed the airplane will seem like a rocket ship going up, thats what inertia does and its the perception of performance. It will make the airplane seem like a hot rod compared to what it was but it just won,t hover.

Whats it cost three bucks? and if you don,t like it then you have an addition for your new 'Prop Wall' Which every modeler that actually flys should have.

John

Shorter prop with more pitch= a faster plane with less pull or torque. Longer prop lower pitch=less speed but more torque. I like to go into a stunt slow and have the pull to do a loop as big as the sky with as much vertical pull as I can get from an engine/plane combo.
If you are looking for speed you wouldn't like my planes, well, maybe you would. I run a YS 1.10 in a 60 size Hots but to slow it down I use a 16X6 on it. I have a 60 size Kaos with an OS .91 FS and it uses a 16X 6 or 4. I can slow my planes down a lot for landings with these props on them and my take offs are really short, the Hots doesn't need to move forward at all!!
I didn't ask anyone else what they were using, I did what John does and spent the time testing until I found my magic prop size, that's the one that will fly the plane the way I want and keep my engines in there working RPM range. Testing is fun and a big eye opener. You can't have too many props!! Nuff Said!!

Thanks. I am fairly new with the props and testing. I started flying few months ago and not ready to hover, but I do like to have that vertical and speed. I like flying low and fast then take it straight up. It climbs a good 600ft estimating. The APC props seem to be better with the plane and eventually I will find the one I like. The MAS would allow me to stall turn it where the APC keeps pullin. So 11x7 and a 12x5 is next in testing. Thanks for the info.

Jason