gunny11

My Feedback: (6)

I picked up my great planes 81" super chipmunk and was contemplating on which gasser to put in it.

Gunny

rmh

Well son- a gasser is the way to go -that's for certain.

Check out page 23 in the instruction manual --
They show a OS1.2 four stroke (these weigh aprox 27 ozs) and they mention and show 20 ozs of lead attached along the motor mount beams.
Also they mention addition ballast can be attached as 1-2 oz spinners.
Sounds like 3 lbs is needed up front?
So - Close your eyes and point at any 35/40 cc gasser.
These range from 2.5- to 3.5 lbs.

gunny11

My Feedback: (6)

Looks like an RCS 180 will actually fit very good inverted. And weight wise too.

PlaneKrazee

My Feedback: (14)

Dick,

Based on your experience, which engine in this range is the smoothest?

Birddog-RCU

My Feedback: (62)

Dick, do you really feel this plane would need a 35-40cc engine? The G26, Roto 25 and RCS 140 are all good replacements for 1.20 4 stroke planes.

GoeKeli

My Feedback: (18)

Roto 35? Is there any room for a canister? I am looking for a project for my 3W24.

Joe

PlaneKrazee

My Feedback: (14)

It looks like it will come in at 14 lbs. The glass is very thin and flexible like a cowl. They must have used a lot of paint or something to get it so tail heavy. The minimum power for aerobatics would be a 1.20 two stroke glow, 1.60 power would be better. The cowl is very small and there is no room for a canister.

I think a G-26 would be the smallest gas engine to pull it around in a scale manner. I haven't seen the M.A.N. Hanson G-26 review. Would it be possible for someone to scan it?

rmh

So far the Roto's get my vote for just plain old smoothness - they run very well .
the mufflers are tiny and a pipe really perks em up.
BUT for a a great sport motor (w/original muffler) that cowls in well - they are hard to beat.
very quiet and good power.
My own 25 is just a gem - I used it on a 10 lb Funtana and it did not shake the model at all .

PlaneKrazee

My Feedback: (14)

Dick,

I remember reading the Roto 25 was very smooth. How smooth is the Roto 35cc compared to the 25cc?

rmh

pretty much the same but a sizeable weight difference- about 12 ounces.
The engines are sleeved, have a drum intake and generally very robust.

PlaneKrazee

My Feedback: (14)

Dick,

Do you have any open exhaust rpm figures for the Roto 25?

There is no room for a pipe in this plane and as you pointed out the 35cc is stout.

rmh

No I don't - I went right from the factory muffler to Ed Skorpa's tuned very quiet 3 oz carbon pipe -

glowplugboy

My Feedback: (17)

The GCBM R/C 25cc. Check it out at [link=http://www.gcbmrc.com]www.gcbmrc.com [/link] . They are running a special through Christmas for $195 + $10 S&H.

AIRPLANENUTS

My Feedback: (2)

I'd love to try one of those GCBM conversions in this plane. I wonder how much tail weight would have to be added? Anyone happen to have the distances from the prop hub to the CG and the rudder hinge line to the CG wo that we can calculate the moment arms?

fwman1

My Feedback: (22)

You can probably forget about the G-26. I have one in my 89" Dynaflite Chipmunk. I had to fabricate a special header and muffler to keep it inside the cowl. The smaller ARF should have an even narrower cowl. That being said, the G-26 does a nice job on my 20 pound Chippy.

Yes, it is heavy. Fully sheeted two-piece wings, robart struts, fully glassed. I built it as a warbird trainer (surprise, surprise), so heavy was actually a good thing.

rmh

well -we are going to assemble one of these Chipmunks (can't really call it building) --and as we have a nice 35 Roto here - it will go in it .
just guessing at the balance - it will likely add up pretty well as 3 lbs plus is what the 35 weighs --and that's what the prototype (according to the instruction manual page 23 ) needed up front.
we did a Kanke Monocoupe with the 35 and it is just flat fun to fly - droop th flaps a tad and it lands level -beautiful wheel touch downs
It also loops and rolls very scale like
big ol barrels and th loops -when throttled back just hang over the top and slowly come around.
a real departure from 2-1 power to weight unlimited aerobatics -but very enjoyable.

PlaneKrazee

My Feedback: (14)

Dick,

The plane with a roto 35 should be a ball to fly. The sikk 29cc conversion engine looks like a good match too. It is supposed to have more torque and top end than a G-26.

I just got done mounting a Enya 1.55 inverted in mine. If it proves to be a dog I'll have to go a more powerful gas engine.

If you get a chance, please post a photo of the 35cc Chipmunk install.

pettit

My Feedback: (23)

My GP Chipmunk uses an OS 120 single, a 5 cell nicad battery strapped to the bottom of the engine mount, throttle servo on the firewall, a 3 ounce heavy prop nut,

and NO ADDITIONAL WEIGHT NEEDED TO BALANCE!!!

Total dry weight is 12 pounds 8 ounces, half a pound less than GP said it would (13-14 pounds in the book)

PlaneKrazee

My Feedback: (14)

pettit,

Have you flown it yet?

rmh

Well -an OS1.2 is a great engine had many of em -used em in pattern planes sport planes etc..
BUT at over twelve lbs ?-a very tepid setup for anything but sea level. A 5 cell nimh is 7 ozs so I bet you hav 7 + 3 - --10 ozs just hung un the front
I really studied this model and it simply is what it is - a nice sport model with heavy aft section.
So the OS 1.2 likely still weighs 27 ozs PLUS a big ol motormount
so thats 27+ 6(?) for the mount and 10 you added OR-43 ounces of engine weight . conservatively
Is my math correct ?
I would bet money that a ZDZ40 would balance with stuff mounted per the kit - they weigh 2.6 lbs then add 6-8ozs for batt n ignition.
It is a very pretty model -we are doing it for a friend .

ply68

My Feedback: (29)

So has anyone installed and flown the GP Super Chipmunk with a gasser? I am getting ready to order my engine. Initially, I was thinking about an OS 120 w/pump but would prefer a gasser if it fits inside the cowl.

PlaneKrazee

My Feedback: (14)

No engine that will fly this plane will fit completely inside the cowl. Without a prop extension even the Enya had to have the cowl trimmed when inverted. That engine follows the cowl slope and protrudes between 1/4-3/8" and it looks pretty good.. I don't think a G-26 or similar size engine would look bad and you will get plenty of cooling.

Dick,

Are you going with the ZDZ 40 over the Roto 35?

rmh

No - I have the ROTO 35 and having used one before in a H9 Mustangand a Kange Monocoupe - I am satisfied it is a beter choice -simply because the setup is very compact and quiet as is
Here is a pic of the 25 in a Pitts (from article in 3D Flyer mag I did).
the muffler is the same and overall size pretty close.

pettit

My Feedback: (23)

Here's the engine installation on my GP Chipmunk: OS 120 Surpass, APC 17-6, 5 cell battery strapped under engine and 3 ounce DuBro hub for balance.

No additional weight needed. Total dry weight is 12 pounds 10 ounces.

Test flights this coming Saturday.

PepsiMike

Picture is worth a thousand.....

Let us know how the test flight goes. Gotta agree with using a small gasser on this one though.