Striver mini VTOL 4+1 QuadPlane

I couldn’t agree more. Greg’s build reports are always as instructive as accurate and helpful. Thanks a lot @GregCovey


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finally finished building my Striver-mini. Build went pretty well, just took a while :slight_smile:
I haven’t flown it yet, but one thing I’m a bit puzzled on is the size of the fwd and vtol motors. A log I got from MakeFlyEasy shows hover at 35A, which seems plausible if lightly loaded. I did a static test of the fwd motor, and I’m seeing over 85A on 6S at 90% throttle. That really surprised me as I expected fixed wing to be drawing a lot less than VTOL hover.
Does someone have a log they can share with me showing a full flight? I’m a bit concerned about the total current in fwd transition (85A + 35A for hover is a lot for XT90s), so I’m thinking about dropping back max fwd throttle a lot, but it would be good to have a log to back that up.

Hi Tridge,

Congrats on finishing your build! We’re going into winter here so my inspiration is lacking. :smiley:

In the Striver 4+1 video below, you can get an idea of the current draw at various points along the test flight. Here is what I saw. The XT90 connector is rated for 100 amp duty ,designed to handle 100 Amps continuously without exceeding 80°C. I’m not sure what the surge rating is.

  • Ascending Hover = 44A
  • Transition = 86A
  • Forward Flight = 5-10 amps.

Striver mini4+1 VTOL Guide 17- Takeoff and landing Route Test

Hi, thanks to everyone for the valuable information shared on this thread. I’m about to finish my build and about to start with the FC configuration. I’m planning on using a Holybro Pixhawk but I’m unsure about Which firmware is recommended to use, the custom one provided by MFE or can I use the normal mission planner method to upload the stable version and then load the param file shared by MFE.

Use the normal Mission Planner and ArduPilot releases. I usually copy over the PIDs (both hover and forward flight) from the MFE param file to my clean param file from the latest stable build.

Good luck!

Thanks @GregCovey . I’ll try it that way. I hope to test it next week! :grinning:


Does someone know where can I buy a "quick release tube clamp "?, It is the piece used to fix the “quad arm” in the wings. I add some images to show it. Maybe someone knows…thank

Video here> 2021 09 27 1 43 07 - YouTube

Hello Again! I managed to get my hands on the parts I envisioned for the VTOL conversion.

This is what I have magaed so far. Any comments are welcome.

The carbon tube is 25x23mm.

The installation seems pretty solid so far by moving the wing around from the carbon tube.

Hi Greg.

A few weeks ago the Striver arrived so I started to build it according to your instructions, but I was wrong and bought the following propellers:

• Cruise flight: APC1612 (
• Vertical flight: 1755 MARKII Matte Carbon Fiber Propeller CW & CCW (

Could you tell me which would be the most suitable for both vertical and horizontal flight considering that I live in Mexico City at a height of 2,240.00 meters above sea level.

I am using the same power system you recommended:

• Vertical flight two motors 5008 / 340KV Brushless Motor / black (TL96020):
• Single engine horizontal flight: SunnySky X Series V3 X4120 V3 480kv (SunnySky X Series V3 X4120 V3 Brushless Motors – SunnySky USA)

But with a 25000 mAh 10C 6S TATTU battery so I have an approximate weight of 7.5 kg. I already did a test flight, but to keep it stable in vertical flight I had to accelerate up to 75%. So I had to adjust the Q_M_THST_HOVER parameter from 0.3121451 to 0.405 so that the throttle stayed halfway. Is what I do correct?

Thank you for your comments.

Hi Alberto,

I am not an expert at flying at high altitudes. Hopefully, someone else will post some tips on doing that. In general, you will want to increase your prop size at 6000 feet.

I haven’t built my wings yet. Is there room for a larger prop than 18x5.5 for the quad motors? My guess is that one end already goes over the wing area. The easiest fix may be to try some 18x8 or 19x5.5 props if you can find them cheap.

Yes, I believe that you are correct on adjusting the Q_M_THST_HOVER parameter. It can also learn this value in QHOVER or QLOITER modes by enabling Q_M_HOVER_LEARN. Sometimes it is faster to just adjust it yourself.

Cheers and good luck!

Your Believer conversion looks great. Just wondering what motor/esc/props you are are using for your two cruise motors?

I have been considering a VTOL conversion for my believer so interested in your setup…



Hi, still working on my build. Last weekend I did some benchtest with the motors included in the kit, here are my results in case anyone finds them useful.motor1


Hey. Thanks for your interest.

The forward motors are sunnysky x3120-III and the forward props are 12x12 apc.

Previously I had been using t motors 3520 motors and 13x12 apc props.

The ESCs are hobbywing xrotor pro 40A. Pretty light.

I have a couple of believers so I have started to convert one to VTOL as a testbed.

Thanks for that. Good luck with your project.



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Mounted both vtol arms on the wings and front vtol motors.

Next step is to cut the vrol arms after determination of backward motors location based on CG.

I have a couple of questions:

  1. How much wing twist should be allowed? Currently, on application of approximately 3kg force on one side of vtol arm, the back side deflects about 2 to 3 cm.

  2. How do the front vtol motors effect the forward thrust motors when the front vtol props cover approximately half of the forward prop when viewed from the front? The current installation barely fits 12x12 inch APC props.

I apologise for hijacking this thread but it seems trivial to start a new thread when all the great minds are already in this thread. If im out of line, kindly let me know so I may move this to another thread.

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Started wiring up one of the wings.

Currently, its a test setup for testing hover soon.

Planning to use 6s7p LG HG2 Li ion battery first.

I have kept the motor spacing for 18 inch propellers. That might bw an overkill but considering the voltage drop, i think it is best to start with a larger prop first.

Any recommendations regarding the wing twist in the above post?

A bit of an update on my Striver Mini 4+1. I’ve done 6 flights now, and the plane is performing nicely with 4.1.x firmware. I’ve done both a VTOL tune and fixed wing tune.
I’ve also updated the default MakeFlyEasy parameters for 4.1.x, you can find the parameters here:
Apart from normal tuning, the key thing I needed to adjust was the Q_A_THR_MIX parameters, which needed to be much higher than normal in order to handle gusts of wind while landing. My flying site has a rising slope where I land, and the wind up that slope can destabilise the aircraft in the stage before it has weather-vaned around to nose into the wind.
I ended up needing a Q_A_THR_MIX_MIN or 0.4 for good stability in landing, which is above the max allowed in 4.1.3 and before, so in the 4.1.4 release I increased the allowed maximum to 0.5.
Overall the striver mini 4+1 is a really nice aircraft to fly!


Completed Some initial setup.

H mixing induced yaw and lots of wing flex, hence shifted to X Mixing.

Tried Hover at a non-ideal place. About 10 to 15 cm off the ground in Qstabilize mode as the GPS environment was not ideal.

A video of the short hover is here: X Mixing QStabilize First Hover - YouTube

Attaching bin log for any comments or suggestions on how to take it from here.

Should I move to follow the VTOL Tuning page in the WIKI?

Today, I had another flight in Qstabilize mode followed by QHover Mode.

One thing I have observed, the quadplane tends to move forward with no pitch input. Maybe it can be adjusted by Q_TRIM_PITCH as stated in the quadplane tips here: QuadPlane Tips — Plane documentation.

If the aircraft tends to move forward, then Q_TRIM_PITCH will be positive, right?

The quadplane also has calculated the hover throttle to be about 0.25. I am using 18 inch props at the moment which are surely an overkill and there is room to reduce the boom lengths by decreasing prop sizes. which will essentially also reduce wing flex. Is it recommended to go this route?

I seriously hope I am not spamming this thread. If I am, kindly let me know so I can move it to another topic.

For the wing flex, I was following the tuning guide at Tuning Process Instructions — Plane documentation, where after step 6 and a bit of manual decrease of D term, the flex is almost all gone. maybe it was due to the control loops overcorrecting. Either way, a significant decrease in wing flex is observed.

Step 7: Re-tried QHover which also performed much better.

Step 8: Yaw Bias while QHover is a mean of -0.04 with a peak variation of up to -0.12 at takeoff. Documentation states it should be less than 10%. Does that refer to peak-to-peak variation or should it be read as ±10%?