Help! Boomen Flerken Questions/Coments

[dhall224]

I have built many FT models, at least a dozen. I have a large size Flerken, which I love, so when the Boomin Flerken came out I bought two combo kits with wheels.

Yesterday I maidened the first one. Very scary I must say. It took off our mowed grass runway and immediately went straight up and tried to do a loop! Startled the heck out of me as I expected it to take off like Josh’s video. Anyway after trying to trim it with little success, I slowed it down and it became more manageable. I was able to land it successfully.

What I noted was that whenever I applied near full throttle it climbed hard. I could only trim it for slow to medium speed on the transmitter.

The other thing I noticed when building it is that there appears to be a lot of positive incidence on both motors, very noticeable. In my mind this would explain the extreme climbing when at high throttle.

My question is, is this flight characteristic normal for the Boomin Flerken? (I hope not, as I like to go-fast in a straight line without climbing!) Also, is the noticeable positive incidence of the motors (per the kit) normal? (I'm thinking about shimming the motors to take it out.)

The last thing is the balance point. I balanced it a little nose heavy per the instructions at 1” back from the leading edge on outside of boom. My 4s battery is hanging half off the ply battery tray toward the center of the plane. Is that normal? The battery tray placement for the Boomen Flerken is not in the correct place?

My last comment is the wheel kit. From my one slightly hard landing, the nose wheel sitting on unsupported foam is not sufficient. My nose cracked in the glue line under the front nose wheel. This won’t stand up very well and should be reinforced in the kit, which I will do with some light ply.

Dave

Here is one of the planes I scratch built! https://www.flitetest.com/articles/ft-x-29-lg-v2-large-scratch-built-w-retracts
Also look for my thread on this page with more photos. (I’m dhall224) https://forum.flitetest.com/index.php?threads/unofficial-ft-x-29.36950/page-5#post-747273

 

[Yankee2003]

I have built many FT models, at least a dozen. I have a large size Flerken, which I love, so when the Boomin Flerken came out I bought two combo kits with wheels.

Yesterday I maidened the first one. Very scary I must say. It took off our mowed grass runway and immediately went straight up and tried to do a loop! Startled the heck out of me as I expected it to take off like Josh’s video. Anyway after trying to trim it with little success, I slowed it down and it became more manageable. I was able to land it successfully.

What I noted was that whenever I applied near full throttle it climbed hard. I could only trim it for slow to medium speed on the transmitter.

The other thing I noticed when building it is that there appears to be a lot of positive incidence on both motors, very noticeable. In my mind this would explain the extreme climbing when at high throttle.

My question is, is this flight characteristic normal for the Boomin Flerken? (I hope not, as I like to go-fast in a straight line without climbing!) Also, is the noticeable positive incidence of the motors (per the kit) normal? (I'm thinking about shimming the motors to take it out.)

The last thing is the balance point. I balanced it a little nose heavy per the instructions at 1” back from the leading edge on outside of boom. My 4s battery is hanging half off the ply battery tray toward the center of the plane. Is that normal? The battery tray placement for the Boomen Flerken is not in the correct place?

My last comment is the wheel kit. From my one slightly hard landing, the nose wheel sitting on unsupported foam is not sufficient. My nose cracked in the glue line under the front nose wheel. This won’t stand up very well and should be reinforced in the kit, which I will do with some light ply.

Dave

Here is one of the planes I scratch built! https://www.flitetest.com/articles/ft-x-29-lg-v2-large-scratch-built-w-retracts
Also look for my thread on this page with more photos. (I’m dhall224) https://forum.flitetest.com/index.php?threads/unofficial-ft-x-29.36950/page-5#post-747273

I just bought the combo.
Glad you started a thread on it. Your aircraft look amazing. I will not be building mine before FF 23 since it is so close. But I will be following until I get started on it.
i have high hopes for this aircraft, can’t wait to hear how we can make it better.

 

[CrazyguyFPV]

I have built many FT models, at least a dozen. I have a large size Flerken, which I love, so when the Boomin Flerken came out I bought two combo kits with wheels.

Yesterday I maidened the first one. Very scary I must say. It took off our mowed grass runway and immediately went straight up and tried to do a loop! Startled the heck out of me as I expected it to take off like Josh’s video. Anyway after trying to trim it with little success, I slowed it down and it became more manageable. I was able to land it successfully.

What I noted was that whenever I applied near full throttle it climbed hard. I could only trim it for slow to medium speed on the transmitter.

The other thing I noticed when building it is that there appears to be a lot of positive incidence on both motors, very noticeable. In my mind this would explain the extreme climbing when at high throttle.

My question is, is this flight characteristic normal for the Boomin Flerken? (I hope not, as I like to go-fast in a straight line without climbing!) Also, is the noticeable positive incidence of the motors (per the kit) normal? (I'm thinking about shimming the motors to take it out.)

The last thing is the balance point. I balanced it a little nose heavy per the instructions at 1” back from the leading edge on outside of boom. My 4s battery is hanging half off the ply battery tray toward the center of the plane. Is that normal? The battery tray placement for the Boomen Flerken is not in the correct place?

My last comment is the wheel kit. From my one slightly hard landing, the nose wheel sitting on unsupported foam is not sufficient. My nose cracked in the glue line under the front nose wheel. This won’t stand up very well and should be reinforced in the kit, which I will do with some light ply.

Dave

Here is one of the planes I scratch built! https://www.flitetest.com/articles/ft-x-29-lg-v2-large-scratch-built-w-retracts
Also look for my thread on this page with more photos. (I’m dhall224) https://forum.flitetest.com/index.php?threads/unofficial-ft-x-29.36950/page-5#post-747273

Love your builds.
I am in the process of building a Boomin' Flerken (first FT build). I'm looking for videos/instructions for putting FPV into it. I want to put a DJI O3 in and am interested in any camera mounts people may have already created or use for this. Additionally, most of the FPV systems will stay on low power until they get an "armed" command so I assume this means I need a FC in the build as well (also for OSD)
Anyone have a link on resolving this issue or other help adding a VTX?

 

[dhall224]

I thought I’d let you know how I tamed my Boomin Flerken somewhat. My problem was that the BF climbed like crazy when at full throttle and did’t have enough elevator authority.

First I added 1/2” to the elevator surface to give me some more authority. When I slowed it down to land I couldn’t get enough to flair.
Second I shimmed the motors removing the positive thrust that was built into the booms. The thrust is now neutral.
Third I removed some weight from the nose so the plane balances per Josh’s fingers in the assembly video. Note it is very nose heavy when balanced 1” back from the leading edge per the instructions.

It flies reasonably well now and I’m still fine tuning it.

One suggestion I would make is to use the 3rd hole out on the small elevator servo arm instead of the second hole, or use the second hole on the larger arm. With the second hole on the smaller arm I don’t have enough elevator authority.
Also I’m not crazy about the white foam board. It seems that the paper delaminates too easy.

I’ve attached three photos showing the plane, the elevator extension and the motor thrust.

Dave

 

[Yankee2003]

I thought I’d let you know how I tamed my Boomin Flerken somewhat. My problem was that the BF climbed like crazy when at full throttle and did’t have enough elevator authority.

First I added 1/2” to the elevator surface to give me some more authority. When I slowed it down to land I couldn’t get enough to flair.
Second I shimmed the motors removing the positive thrust that was built into the booms. The thrust is now neutral.
Third I removed some weight from the nose so the plane balances per Josh’s fingers in the assembly video. Note it is very nose heavy when balanced 1” back from the leading edge per the instructions.

It flies reasonably well now and I’m still fine tuning it.

One suggestion I would make is to use the 3rd hole out on the small elevator servo arm instead of the second hole, or use the second hole on the larger arm. With the second hole on the smaller arm I don’t have enough elevator authority.
Also I’m not crazy about the white foam board. It seems that the paper delaminates too easy.

I’ve attached three photos showing the plane, the elevator extension and the motor thrust.

Dave

Thank you for working some of the issues out and documenting them here. Mine is on the build table ready for when I return from FF.
Did you just literally glue 1/2” on to the back of the elevator and trim it out white?