Happymodel Larva-X: Testing battery and propeller combinations

The stock Larva X comes fitter with Emax Avan props and no battery

Introduction
That Happymodel Larva-x is a great value bind and fly ultralight toothpick-style quad which I reviewed and provided and improved tune for here. This is their first model to come without a battery which is due to the fact that many international shipping suppliers are banning lipo batteries from shipment. Stock propellers are the Emax Avan Rush 2.5 but due to supply issues HQ Prop 2.5x2.5x3 are also included as spares. My full review is here where I flew almost exclusively on the HQ 2.5x2.5x3, not because they were necessarily better but because they were less stiff and transmit less impact to what is a relatively weak motor (see my review for more details including a response from Happymodel).

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If you're new here you'll find I'm never satisfied with status quo and like to tinker. Propellers and batteries are dispoable items so I've chosen to share the outcome of my tinkering with these. What I did find however is that this quad is very sensitive to these combinations and although some improvements can be had, there are also some very poor combinations that are inefficient and noisy with less than stellar performance.

The HQ T65mm has emerged as the prop of choice for 65mm toothpicks in general

HQ T65mm Propeller - Theory
This prop was released around the time the Happymodel Larva-x specs and based on a paper excercise I thought it would be ideal for the following reasons:

• Much lighter weight than a typical 3-bladed prop would make the whole craft lighter
• Less blade area would make for less load that should be better suited to the 1103 motor
• More efficient
• Relative light weight should still mean reasonable grip only with 2 blades
• More flexible blade should mean less impact transferred to motor in crash

The caveat is though that the low pitch of this prop would mean that 3s is a necessity and that in general less blade area = more noise.

Weight with the stock HQ 2.5x2.5x3 propellers

Impressive weight loss with the HQ T65mm propellers

HQ T65 - In practice
Firstly, as you can see from the images above, the HQ T65mm props are a full 2.5g lighter across the set compared to the HQ 2.5x2.5x3. This is a lot of weight (5% in fact) for such a small quad. If you are brave enough to use these without screws you can acutally save another 2g total.

As expected 2s was too slow on this prop: low motor kv, low prop pitch and only 2 blades means that this is not worthwhile on 2s unless you simply want maximum endurance.

On 3s these props are fast but they are not as good as I thought and here's why:

• The are louder
• Since the motor has much more authority over the propeller the tune needs to be much more tame
• They are very sensitive to weight by way of battery size.

450mah is simply too much weight for this to carry. It's goes from being very quiet to being suprisingly loud which is a sure indication that props are overloaded. Furthermore handling is pretty loose even when the tune is on point.

300mah 3s is about right - it's quieter (not as quiet as 3 blade) and it is easier to tune. You will need a good battery though and I strongly recommend the GNB HV 80c 3s 300mah rather than the Tattu 3s 300mah I was using. If you can perservere you'll be rewarded with some impressive speed. I only had a brief play but you can see my results in the DVR below.

HQ 2.5x2.5x3
I think these will be my prop of choice moving forward. They just seem to offer so much more versatility on this particalur setup and for me the advantages as listed below certainly outweigh the surprisngly small disadvantage in speed and efficiency:

• MUCH quieter (key when flying nearby people or in small parks)
• Wider range of useful batteries: 2s, 3s, 300-450mah all have their place
• Better grip through turns
• Less vibration as 3 blades are naturally better balanced

To show you that you can still have fun on 2s with these, here is some DVR I captured below running 2s 450mah for 5 minutes of flight:

​Thanks for reading, if you found this article useful please feel free to like or share, the facebook links below directly link/like this article. Links are affiliated and help me buy the bits I need to produce this type of content. If you are looking for quads or parts check out my coupons and discounts page which I keep updated with only the parts and quads I like at a proper discount.

Here's all the parts mentioned in my review:

Happymodel Larva-x lightweight quadcopter

HQ 2.5x2.5x3 prop - my favourite all purpose prop on the Larva-x

HQ T65mm prop - the fastest prop on a lightweight 3s but not well suited to the Larva-X

GNB 3s 300mah 80C battery - my favourite lightweight 3s battery.

GNB 2s 450mah 80c battery - my favourite 2s battery with the HQ 2.5x2.5x3 props