blhollo2

My Feedback: (278)

hello, i recently bought a .61 GMS motor to put in my cherokee, the cherokee says up to 55Ax, but I want to over power it, are there any negatives to having this much pep other than weight?

opjose

It should not be a problem.

RCKen

My Feedback: (9)

I reviewed this plane for RCU and I had the 55 AX on it, and it was really too much engine for it. With the 55 the plane will do 100+mph (verified with a radar gun). Putting at 61 on it in my opinion is way too much for it. There is more than enough power with the 55 in it, and with a 61 all you will be doing it adding extra weight on the plane. Plus, you will more than likely have problems getting the 61 to fit under the cowl.

Why do you want such a large engine on this plane??

blhollo2

My Feedback: (278)

hey RCKEN thanks for the post,

wow the 55AX will make it go 100+mph!! Thats fast, I wanted the .61 on it so I could get some more speed and performance out of it, I was very impressed with it when I had the TT .46 Pro on it.. do you think the .61 will stress the plane?

RCKen

My Feedback: (9)

Yes, I do think the 61 will put too much stress on the plane. Also, you won't be able to get a prop for a 61 on this plane. There isn't enough ground clearence. I wanted to use a 13x6 prop with the 55, but I had to go with the 12x7 because there was barely enough clearence for the 13" prop. I would have had prop strikes when landing.

Ken

opjose

Actually the GMS .61 and the AX .55 are about equal in power output.

Prop the plane correctly and there should be no issues.

Hint: 3 blade props....

RCKen

My Feedback: (9)

Well now, this is interesting. When I reviewed the plane the specs called for a .40-.46 on it. Now they have changed the specs to read .40-.56. very interesting.

If the 61 and the 55 are close in power output then why not stick with the 55?? It weighs less than the 55, and it's going to be easier to fit in the cowl.

Trust me here, the 55 AX has more than enough power for this plane. I rarely use full throttle when flying it. In fact, I'm considering pulling the 55 AX out and putting a 46 AX in it instead.

Ken

Jetdesign

My Feedback: (8)

I had the 55AX in a Phoenix Decathlon, which is a much wider plane than the cherokee, also is a high-wing with a longer wingspan, so it's has much more drag. The 55AX was/is a great engine in that plane, especially once it's run in at max performance.

The cherokee is designed to be sporty, but not a true aerobat or 3D plane - I don't see the need to put in a .60, and this is coming from a guy who LOVES high-powered planes.

The 55AX is a great engine.

skyraider71

I wouldn't go any larger than a good .46, or .56 to .65 four-stroke. The Cherokee just
doesnt need it.

opjose

I believe he already has the GMS .61.

He can move the battery back a bit, and with the available muffler options, mounting it should not be problematic.

Jetdesign

My Feedback: (8)

I misread it too. If it were me and I had the plane and the engine, I'd put them together. Beef up the firewall, and use some good throttle management.

blhollo2

My Feedback: (278)

yeah I have the .61 engine already, I wish I had bought the 55AX the GMS.61 Reportly pulls 2.0hp and the .%%AX Pulls at 1.7hp...hmmm, So what would u guess with the .61 engine on the cherokee the speed would be?

Jetdesign

My Feedback: (8)

it really depends on how you prop the plane and how you fly it. best thing to do is break in the engine with whatever prop range is says in the manual and change it from there. you want more speed, use a shorter prop with more pitch. you want better climbing, use a longer prop with less pitch.

it's hard to predict airspeed. i have a Venus II that is 66" wingspan and 70" long. I thought it was my slowest plane, yet it passed the radar at 90mph.

ChuckW

Pay no attention to advertised HP numbers. They are a very unreliable guide to actual performance. A nice .46 such as the OS .46-AX is all that the Cherokee needs. A .55 would just be that much sweeter.

I think the .61 is a bad idea. There is a weight penalty that comes along with the extra displacement. This will not only affect the CG but you may very well notice the added weight in the way the pane flys. CG could be compensated for by putting the receiver battery to the rear but extra weight is hard to shed.

I'm not saying you can't make the .61 work; it is definitely possible. What I am saying though is that you may actually be happier with the recommended engine. This is a sport aerobatic plane, it doesn't really benefit from being overpowered like a 3D airplane.

RCKen

My Feedback: (9)

Chuck has a great point here. When it comes to an airplane there is nothing for free. If you want to put a bigger engine on an airframe there is something that's got to give somewhere. The GMS engine weighs 7 ounces more than the 55 AX I used. So with the engine and any extra weight you need to balance the plane with you are going to be at, or exceeding, the max recommended weight of 7 lbs 4 oz. The extra weight is going to make for a high wing loading, which will make the plane more likely to stall and snap at slow speeds. Plus, this high weight combined with the extra speed you want to fly at is going to make the airframe more likely to fail. There are some manuevers that I won't perform with mine at a full throttle as I feel that it's putting extra stress on the wing and I'm afraid it may fail. This will be ramped up with extra weight and speed.

I'm not telling you to not do it. You asked for an opinion on this combination and I gave you mine based on my experiences with this plane (close to 100 flights now). From my time with this plane it doesn't really benefit from extreme speeds. If you want a plane to go fast look at something like the Hangar 9 Sundowner as it's designed to go fast. The Cherokee is more enjoyable and more fun to fly by not flying it fast, but rather having fun with it's aerobatic capabilities.

Ken

blhollo2

My Feedback: (278)

RCken I agree with you, i think im going to stick with my OS .46 FXi and call it a day

ChuckW

Just as a side note, my Cherokee balanced perfectly with a .46-AX. I did not have to move anything or add weight. When I built a heavier electric version, I had to move the receiver battery far back in the fuselage. The extra weight made a nice flying plane into a less enjoyable one in my opinion.

blhollo2

My Feedback: (278)

hmmm..

Kostas1

Hey there!

I used an APC 12x8 on my Saito FA-80.

While the engine is inverted....

Check my assembly thread here : [link=http://www.rcuniverse.com/forum/fb.asp?m=10419268]GreatPlanes Cherokee 40 ARF assembly thread![/link]

I am sure it will help you out!!!

Kostas1

Oberst

Way too much engine. A O.S.46AX would be perfect for that plane.

I second Kens advice.


Pete

Kostas1

Pete,

if you think my engine is "too much" please see the video, on last page of my assembly thread!

JohnBuckner

My Feedback: (1)

If you want to fly fast cheaply (and there is nothing wrong with that) then get one of these cheap ARF's:

http://www3.towerhobbies.com/cgi-bin...?&I=LXEUN4&P=7

Hang the TT .46 you dumped off the Cherokee on it. Quit screwing around with the fat winged sport airplane. Use an APC 9x7 on the TT using 15% and the muffler you will turn something over 16,000 and the airplane will easily hit about 120 mph.

Treat the airplane like the racer it is and don,t try to taxi and do slow throttle up takeoffs and just shut the engine off in the pattern and it will be very easy to fly and land.

John

wobblewobble

Its not enough put a YS 110 in it

kiwibob72

Don't know about that specific plane,but I do have a 2 stroke ASP .61 in a 40 sized trainer that I brought 2nd hand, not hugely overpowered, but I can just potter around at 1/2 throttle and get 12-15min out of a single tank!

Kostas1

Why are you so sarcastic ; I have first hand experience with this airframe/combo....