looking to slow my trainner down without a new engine?
 

I have a tower trainner 40, and I put a O.S. 46 AX in it. The manual recommends a 10.5X6, 11X6-8, 12X6-7 size prop. I have a 11X6 on it now and my club trainner would like to slow it down. any recomendations on how to do it without buying a new engine? he recomended a 11X5 prop and thought a longer prop may not be very good for the engine. Oh, the O.S. manual has the props listed as sport and dosent list any other recomendations.



all recomendations are appriceated and will be tryed, thank you.

RE: looking to slow my trainner down without a new engine?
 

Yes, you can use an 11x5 prop or even an 11x4 prop. This will help to slow the plane down as compared to a 11x6

RE: looking to slow my trainner down without a new engine?
 

you should reduce the pitch on the prop that would help big time i have also shortened the prop by one size and left the pitch the same

RE: looking to slow my trainner down without a new engine?
 

Ditto on the recommendation to drop to an 11x4 prop. That will slow the plane down quite a bit.

Ken

RE: looking to slow my trainner down without a new engine?
 

Another one for an 11X4 APC

RE: looking to slow my trainner down without a new engine?
 

Depending on ground clearance, you could use a 12x4 and slow it down even more.

I don't see why any trainer of the usual size should ever have more than 4 inches of pitch, yet you see 10x6s routinely. Just makes landing harder.

Jim

RE: looking to slow my trainner down without a new engine?
 

An 11-4 will help. However, an 11-4 is light for a .40 and a .46 AX is overkill. You are going to be turning MORE RPM, Tell your instructor that the throttle does NOT have to be full forward regardless of the fact that he can push it there. :eek:
With a Tower trainer 40, a good .29 will fly it well. A .46 AX is real overkill. Simply throttle back to a comfortable cruise speed and work from there.

RE: looking to slow my trainner down without a new engine?
 

i agree with the last statement. a 46 flying an 11 x 6 on a trainer is slow enough. there is no need to fly any slower than that. i flew that combo on my first flight and it was easy breezy. moving to a 12 x 4 may slow it down but really there is no need. i can't imagine a situation where that kind of prop would be needed for training. as hossfly said, throttle control will be the way to go IMHO.

RE: looking to slow my trainner down without a new engine?
 

Also they make props that are wider that will help slow it down and no need to fly it as fast as it will go. Fly about half throttle if you need to. I had a 40 and a 46 and not all that much difference really that cannot be compensated by throttle and prop pitch. You could also limit servo travel to a set point by working with the linkages.

After you fly it for some time you will be ready to rip the sky up with it anyway. If it is the club trainer a different prop might be the best way to go.

RE: looking to slow my trainner down without a new engine?
 

G'day The main advantage of using a lower pitch prop on an overpowered model is to allow the model to slow down when the engine is idling to let you land more easily.

For this reason I usually use 5 pitch props on my trainers.

The AX 46 will happily spin a 12 x 6 (a friend has quite a heavy model of a PC-9) flying really well with this combination) so a 12 x 5 would be a good start. The engine will happily swing the 12 inch prop and this will keep the revs and the noise down too. Or you could try an 11 x 5 as well.

There really is only one way to find out. Try some props and see which you like.

RE: looking to slow my trainner down without a new engine?
 

For that .46AX I'd also recommend an 11x5 or a 12x5. It would depend on ground clearance. An 11x4 just sounds like too little a prop (pitchwise) for this engine and you risk over-reving.

RE: looking to slow my trainner down without a new engine?
 

Changing the prop will help, but you might also consider moving the CG back a little.

If the plane is nose heavy, it will fly faster than if it is balanced properly

RE: looking to slow my trainner down without a new engine?
 

An 11x4 will spin faster than a fast spinning thing. If you want to drop the pitch then opt for a 12x4 to keep some load on the engine.
The increase rpm of a 11x4 may actualy make you fly just as fast but slow you down like a chute was deployed when you throttle back.

I find on the OS 46Ax, the 11x6 provides excellent throttle response and a 11x7 even better and landings are fine.
 When I fited an 11x5 my rpm increased and the plane actually flew faster and the vertical was better too.

I find this is more clearly noticed on my GP Escapade. With the 11x6 she flies fine, fit an 11x5 and shes a lot more lively.

RE: looking to slow my trainner down without a new engine?
 

Try changing prop pitch?

RE: looking to slow my trainner down without a new engine?
 

Put the prop on backwards. That's an old free flight trick to slow the plane down for testing.

RE: looking to slow my trainner down without a new engine?
 

I agree with many here. You should look at a 12x4 so that you dont over-rev the engine, provided of-course that you have the prop clearance.

However, I believe, its better to fly a trainer with a medium pitch prop. It will prevent you from slowing down too much and stalling at landing. I learnt on a trainer with a 55ax and 12x6 prop. I broke the prop after 6 months and by then I wanted to leanr aerobatics. So we put in a 11x6 then and it flew aerobatics much better (it had a 65" span semi-symmetric wing). On my second airplane, Tiger-40, I went all the way upto 11x9 before I settled on a 12x4 mainly because it isint that stable at landing (Its a Phoenix Tiger not CG). I now use 12x4 or 13x4 on my Reactor because it remains controllable at a speed lower than a trainer.

Better would be learn on the 11x6. To slow down the airplane, you just need to go to idle a bit earlier

Ameyam

RE: looking to slow my trainner down without a new engine?
 

Go to a 3blade for slowing it down. 

RE: looking to slow my trainner down without a new engine?
 

I agree with Hossfly. There's nothing that says you have to use full power if you don't want to. You can adjust your throttle linkage so that you can't get full power from the engine. Or if you have a computer radio it's very easy to adjust your travel limits. I would rather do that than put too light of a prop on there.

RE: looking to slow my trainner down without a new engine?
 

Agree with Hossfly, changing props, putting them backwars, set limits in the transmitter, change the CG. Putt the  throttle back, back on the elevator a little and the plane will slow down without any changes.

RE: looking to slow my trainner down without a new engine?
 

Spider, I have a Tower 40 trainer with an OS Max 25 on it. It came out very nose-heavy and landed too fast. Thanks to help from this forum, I figured out the CG problem and moved my battery toward the tail. It made an amazing difference on landing speed.

Lower pitch props will make sure your idle (which is great on the engine you have) doesn't develop too much thrust so the 11-4 suggestions are good ones. Here is a link to a bigger wing I built for mine to slow it down even more. The Tower Hobbies Trainer 40 is a tough bird and a good flyer once the CG gets in the right place.

http://www.youtube.com/watch?v=4EkaU9emYWU

BTW, my CG is 8 cm back from the leading edge of the wing.

RE: looking to slow my trainner down without a new engine?
 

Does that OS .45AX have a carburator, and does the throttle stick on the transmitter move it? If so THROTTLE BACK....!!

RE: looking to slow my trainner down without a new engine?
 

12 x 4 should not be needed on that plane and that engine unless you are trying to hover with it. I'd go with an 11 x 5 or a 10 x 6, but you can really rev up a .46ax with a 10 x 6 if you insist on pushing that left stick all the way foward. I'll also second Minnflyer's suggestion to move the cg back a little. It will help the plane land slower and it will be more fun to fly as long as you don't go too far back on the cg. ;)

RE: looking to slow my trainner down without a new engine?
 

We typically use an APC 12.25 x 3.75 or 12 x 4 on a trainer...unless prop to ground clearance is an issue. If that's the case, then maybe an 11.5 x 4 or an 11 x 5

Naturally, proper throttle management is part of the learning curve....as some have already mentioned, that's why they put carbs on the engines...;):D

RE: looking to slow my trainner down without a new engine?
 

If you run a 10X5 three blade Master Airscrew you will have fantastic aero-braking for low, steady descent speed and lots of power to pull out of trouble without over revving. A side benefit is more ground clearance. Do not confuse this prop with an Evolution trainer three blade, I refuse to teach with those on a plane and install a APC 11X6 or black MAS 11X7.

RE: looking to slow my trainner down without a new engine?
 

11x5 is a great prop for that engine and plane. Hold a little back pressure on the elevator to set a slower speed approach.

RE: looking to slow my trainner down without a new engine?
 

Hi!
11x6 is just fine! 12x4 is even better on a High winged trainer. Just use throttle to control decent!

The first thing to do when flying a plane is to check the C of G ...up high. The goal is always, regardless of plane typeto have the C of G placed so that the plane will stall when the speed is reduced to a near stand still and at the same time have full up elevator.
If the plane just mousses forward at that point the C of G is located too far forward. -Simple as that!

RE: looking to slow my trainner down without a new engine?
 

In general I find MAS props are a little slower than APC props of the same size. So in addition to changing size/pitch, I'd suggest going with an MAS over APC.

RE: looking to slow my trainner down without a new engine?
 

thank you everyone, this is a great help.

RE: looking to slow my trainner down without a new engine?
 

If you have an APC (grey) on the plane, change it to a MAS (Master Airscrew) black with the squared off tips. That MAS is only about 80% as efficient as the APC.

My Sig Rascal 40 with an OS 46FX and APC 11x6 refused to land !! It would float 6" off the ground the full length of the field (600'), unless I killed the engine and did a dead stick.

I changed the prop to a MAS 11x5 and now the plane lands with no problem.

RE: looking to slow my trainner down without a new engine?
 

The props listed in the tech notes and manuals are just guidelines. The manufacturers will never be able to test every possible combination. You can use any prop that runs well without overheating and flies the plane the way "you" like.

You could switch to a 10x5, three blade such as http://masterairscrew.com/new10x53-b...propeller.aspx
The engine will likely turn several hundred rpm more than with the 11x6 but top speed "should" go down by about 9 mph.

If landing speed is the issue, I do not believe the prop is the problem. At 2500 rpm, a 6 pitch prop would only want to go 14 mph under laboratory conditions so I think the others are right that the plane is coming in 'nose down' and gaining speed because of that.

RE: looking to slow my trainner down without a new engine?
 

Ihave to ask, is the teacher trying to slow the plane down on landing or the top speed?
Ihave been flying my Tower40 trainer with a Magnum 52 four stroke and recently with an Irvine 53! http://www.rcuniverse.com/forum/js/f.../omg_smile.gif
Ifind the ground clearance to be an issue with 12" props and not that much fun with 11" . Iprefer 10" props to keep it from mowing the lawn or striking the ground on a rough landing. Nothin wrong with 3 bladed props and lately I have been using some 10" wood Zinger wide blade props that can really move the air. A 10X8 Wide is currently on my Irvine 53 and it is working fine.

Does your Tower40 fly tail heavy even though the balance is correct?

RE: looking to slow my trainner down without a new engine?
 

As I mentioned in my earlier post, my CG is 8 cm back from the leading edge of the wing with no fuel. It trims hands off at half to full throttle, and below that, a couple clicks of up and it again is trimmed for hands off flight on either the original or my bigger wing. Great flying airplane and it lands very slow with excellent flare capability even at low speed.

RE: looking to slow my trainner down without a new engine?
 

no, it actually fly's nose heavy when fueled. He is wanting to slow it down on all aspects. like in the patern and on aproach. We curently fly on half throttle. today I flew a 11X5 prop and on a bad landing I brok it. the only other prop i had was a 11X6, and I really see the diffrence. the 11X5 made a better beginner performance, but the 11X6 gave me unlimited climb.

RE: looking to slow my trainner down without a new engine?
 

almost forgot, I did see the video. Ilikethe bigger wing. looks like you get great performance.

RE: looking to slow my trainner down without a new engine?
 

If you are trying to slow it down on landing just getting a good low idle speed may help. Ishoot for 2000 to 2500 rpm consistently. Ihavent seen any trouble at these low rpms with any prop Ihave ever used. As far as top end you could always use a 3 blade 10" glass filled nylon like a Master Airscrew or Graupner. You can probobly get away with a 5 pitch. Iprefer the MA props for their ruggedness.

RE: looking to slow my trainner down without a new engine?
 

Like several posters have offered, moving the CG back would likely have the biggest effect on your approach speed. Idle and props do have an affect, but the Tower Trainer with a proper CG can almost land itself at many low power settings.

When a plane is nose heavy, the horizontal stab and elevator are not effective in getting the nose up to slow the approach speed. A heavy nose will pull the nose down and the plane speeds up even with back pressure on the stick. Get the CG in the right place and the elevator can be effective in placing the aircraft in any attitude for speed control.

RE: looking to slow my trainner down without a new engine?
 

I played with the CG on my Skylark 70 just as you suggested. I ended up with a plane that will do the circuit just as pretty as you can imagine. Then, I follow the downwind, base, final type of approach, following the "rules", and it glides in just about perfect each and every time.

One day, I was flying with my head up my butt.. I had the wind backwards, and was actually landing with the wind rather than with it on the nose. The landings were long.. every darned one of them, until someone said that my downwind landings were nice, but long. I looked at the guy like he had three heads, then suddenly realized what I was doing. But, even the long landing approaches were nice because everything was right (except for having the nose into the wind, of course).

I pretended that I had intended to land that way, we all had a good laugh about it, then I proceeded to land correctly. Geee.... the thing landed right in front of me for some reason. BUT, again, the flair at the very end of the glide slope was pretty as a picture... and it was because the CG was in the sweet spot.

CGr.

RE: looking to slow my trainner down without a new engine?
 

Ilearned on the PT-40 trainer and now have a Tower40 (due to an electrical failure) and find the Tower40 doesnt fly as well.
Perhaps it is the uber low wing loading? Ijust dont know, but it isnt half as nice to fly as the PT-40.
Flies like it is tail heavy even though it balances out. Ihave tried changing the CG, engine thrust angle, tirms, aileron angle,just dont have it yet.
It has been suggested the wing incidence needs changed.
Anybody else have this trouble?

RE: looking to slow my trainner down without a new engine?
 

I agree..........I'm flying a GP Escapade with an OS46FX and I'm running a Master Airscrew 10x6 and it's quite docile......a good fit for that engine.

RE: looking to slow my trainner down without a new engine?
 

OOPS, I didn't notice that you said a "3-blade 10x5" but the 2-blade 10x6 is still a good choice.