Easy Built Hellcat

[Piecost]

8 May 2026

My first outdoor flying session of the year was under stormy clouds, but light winds. This was a couple of hours before sunset so coincided with the reduction in breeze strength and reduced the risk of strong thermals beneith the towering cumulous clouds.

I had intended to confirm that the trim was unchanged from last summer, then to trim the tips of the original propeller to enable a thinner motor to be used. As usual, my plan did not survive long and differed from reality.

I had found a graph of typical motor width versus total model mass [see attached] Considering the total mass of just under 100g, the graph suggested a motor width of just over 1 inch, whereas I have employed 8 strands of 3/16 which is 1.5 inches. This confirms calgoddard's employment of 8 strands of 1/8" as being about right.

For this evening; I installed the last used 25g motor of 8 strands of 3/16" with the original 35 degree pitch propeller.

I employed my new torque meter as a replacement for the spacer with my blast tube. This worked very well and I was very pleased with it.

I started very conservatively at 50 turns to get a powered glide. Even with the Gurney replaced; the model often turned right under power and left on the glide.

I did not realise that the LH yaw rudder Gurney had fallen off. Its replacement did not prevent the model turning right under power.

I tried reducing the right thrust, but I was at the extreme limit of the adjustment, so inadvertantly reduced down thrust as well. This caused a zoom climb and a stall into a turn.

I tried launching left wing low to force the turn direction but it caused a tight left turn and spiral dive.So, I reverted  to wings level launches.

I packed 1/16" under the tailplane leading edge in a desperate attempt to kill the zoom. This seemed to help and since the model landed with some turns remaining; the glide was not compromised.

I worked up to 260 turns and 450 g.cm torque. The model gently climbed up to a dozen feet with a right turn; transitioning to a slight left as the power came off. It coped well with the turbulance; demonstrating ample stability.

I was a little frustrated that I had lost the trim from last year, but was happy that the model still worked and I finished the session without damage.

I think that it is not worth spending more time getting the old trim back with the too chunky motor. So, I will switch to the 32.5 degree propeller and revert to the 8 strand of 1/8" motor. If that is still underpowered then I will switch to the 30 degree propeller.

I will also remove some noseweight to achieve the Deloach/McCombs recommended CG position. I hope that this needs a more moderate thrustline adjustments.

[Jmk89]

I employed my new torque meter as a replacement for the spacer with my blast tube. This worked very well and I was very pleased with it.

Is the torque meter home made or bought in? Either way, I'm interested in some details, if you would give them.

[Crabby]

I made a torque meter and bought one. My reason was it's a way more accurate way to get repeat results than counting winds. My home-made torque meter was very good but it broke because of ham-fisted soldering. The bought one serves me well.

 Piecost,Great patience is exhibited in your trimming. Frustrations lead to a knit brow but stiff upper lip and one muddles on as they must.

I love the Hellcat, the real one almost as much as the model.

[OZPAF]

Even with the Gurney replaced; the model often turned right under power and left on the glide.

I wonder if the right wing is twisting under power and generating excessive washout?

John

[Piecost]

Jeremy,

Find below a link to my homemade torque meter.

https://hpa.aeromodelling.gr/index.php?topic=337.0#new