The most I would stuff into the nose of a Nobler would be a LA .46
I disagree..
The question of " Is the st .51 to much engine for a Nobler " I can answer.
As far as power I'd say no - Would I put one in ? the answer is also No. - For the reasons below.
SPECS: Bore: 23mm (.905")
Stroke: 20mm (.787")
Weight w/o muffler: 313g (10.98oz)
Weight with muffler: 459g (16.2oz)
I regularly run ( and have won multiple National competitions in Classic Stunt ) with a 1951 Nobler powering it with a Stalker .61
yes STALKER .61 - So that is far more power than your St .51 - The problem I see for the ST 51 is weight.
You can see the specs show that the weight is 459 G with the muffler - and the muffler is side mount.
2 Main problems with the ST 51 is weight and weight balance.
The muffler weighs 146 Grams Engine 313 Grams Total : 459
Having THAT much weight makes balance for a little nobler extremely difficult - As I mentioned I run the Stalker .61 and more specifically the EX Lite edition. with rear exhaust light weight muffler.
Specs on that are : Muffler weights 45 grams and Engine 315. Total : 360 ( Thats 3.4 Oz LIGHTER )
The 2nd issue is the weight balance point. With a rear muffler the total weight is actually moved back further by at least 8 - 10 cm.
So not only with the rear exhaust is the muffler lighter but its moved further back.
This makes a huge difference to the balance point. Overall the weight is moved too far forward with the ST 51 - you have a huge amount of weight in a very concentrated forward balance point.
Even when running a Tuned pipe, you have the weight of the Pipe, but its so far back behind the CG that is doesnt matter to much - compared to having that all located within the front few inches.
So to much power ? God no.. Ive even run the Stalker .66 in the nobler. If your around at the US NATS - I will have a new classic model with stalker .61 with special Ultra light Custom muffler - flying in classic so you can make your own assessment of if its too powerful.
To give you an idea the Stalker .81 is still lighter than the St 51
- I dont have the specs infront of me but i suspect the PA .75 with tuned pipe would also be lighted than the ST .51 w/muffler.
I've had several noblers ( 10 + ) with everything from Veco .29 Upward.. im not advocating everyone putting an engine of my size inside. I do agree that there is alot of engines Like the Brodak .40 that will run it PERFECTLY. and the Aero .36 works exceptionally well.
Others have flown my nobler and EVERYONE has said - Its so easy to fly - Someone said " its like cruzing down the freeway in a Musclecar with modern engine and suspecsion. Just tickin along. With that much power - Ive flown it as slow as 6.5 second laps and make it REALLY slow but still drive slowly through the pattern.. Or you can dial in your speed as you see fit. Such a wide window of operation.
I personally have mine set up like other notable experts fliers have current CLPA models setup - Big bore engine, low down thumping power constant 4 stroke, constant speed. - Simply put results speak for themselves - Lots of torque with reliable power, reliable manouver speed over various conditions and various atmospherics.
Over kill ? Possible but as Randy smith says we now live in an age where we know how to set up engines for run characteristics that are favorable to Stunt. - Be it classic or CLPA.