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Hobby People - BH Models OV-1 Mohawk Twin ARF Review

Mike Llewellyn looks at the new BH Models OV-1 Mohawk ARF. This US Army twin is designed out of the box for electric flight and it looks fantastic. In the air it is an excellent performer making this ARF a great addition to your hangar.

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Introduction


Wingspan:57”
Wing Area:542 sq”
Wing type:Built up - Symmetrical
AUW weight:Advertised – 5lb 1oz Actual - 5lb 4oz
Length:47.2”
Wing loading:22 oz/sq. ft.
Servos:6 Micro/Mini
Transmitter:Spektrum DX7
Receiver:Spektrum AR6200
Battery:Impulse 4000mA 3s LiPoly
Motors:KMS 2814/06 1290Kv Outrunner
ESC:Motrolfly USA 30 AMP
US distributor:Hobby People
BH Models OV-1 Mohawk:OV-1 Mohawk
ARF Price:$189.99

Hobby People imports a wonderful line of ARF airplanes made by BH Models. For those who have not seen this impressive line do not let the budget price fool you. BH Models planes are well built, have scale lines, and they look fantastic, and their version of the OV-1 Mohawk is no exception. This remarkable twin is a highly prefabricated ARF and will be ready to fly in a short time.

The review package shipped from Hobby People, and it arrived in great shape. It is well packaged, double boxed, and the contents in the box are very well protected. All parts are individually protected with cardboard separators and plastic wrap.

Kit Contents

Kit includes:

  • Built fuselage, wing and tail surfaces all covered in genuine Oracover
  • Pre-attached canopy and pilots
  • Factory hinged flight surfaces
  • Hardware (Push rods, horns, clevis, tires and tail wheel assembly)
  • Decals and markings
  • Picture assembly guide and text instructions

Kit requires:

  • 2 - 250+ watt Motors
  • 3s LiPoly battery
  • 6 Servos (2-Flaps, 2-Ailerons, elevator, nose steering)
  • Receiver
  • 4 channel minimum transmitter

Included for this review:

Assembly

The Hobby People BH Models OV-1 Mohawk did require some assembly, but the tough work is done for you. This ARF was ready with just a few hours of assembly work. I was very impressed with the build quality and the scale lines of this ship; a true highly rounded fuselage like the OV-1 has is not easy to replicate. The balsa and plywood used was of good quality with many "holes" laser cut for weight savings.

Done by the factory:

  • Surfaces hinged ready for CA hinges and glue
  • Push rods installed and ready to hook up
  • All surfaces covered
  • Canopy and pilots installed

The builder needs to:

  • Install the tail surfaces
  • Install the nacelles
  • Install radio system
  • Install the power system
  • Apply self adhesive decals

Wing

The wings have cutouts intended for small 9g servos. This allows for short linkages that go directly from the exposed servos to the control surface horns. Each aileron uses a 9g Airtronics servo. The wings both have pull strings installed for the aileron servos - a great touch.

Flaps are in each wing half and are also actuated by a single 9g Airtronics servo. No pull sting is needed here as the servos are located close to the ribs, and mine easily dropped through the wing rib holes to the root rib wing ends.

I was thrilled to see that BH models designed this model specifically for electric flight, saving weight and allowing the use of smaller components like smaller, lighter servos. Have no fear... these small Airtronics servos are light and powerful and offer plenty of control authority.

Motors

The motors mount right to factory installed plywood motor mounts. They included blind nuts and bolts to mount the motors. I highly recommend both the split washers and thread locker here to keep them secure.

The OV-1 Mohawk came with two beautiful fiberglass motor nacelles. The glass work and paint was remarkable, and they look fantastic. Also included are two fiberglass nacelle belly pans.

The nacelles are retained by the included hooks - as are the belly pans. The tops push "back," and the pans push forward and are retained with a single screw so they interconnect and keep each other from moving around.

Wing tube

The wings are not permanently attached to the fuselage. Included is a thin, long aluminum wing tube and plastic thumb screws that secure the wing to fuselage.

Landing Gear

The gear mains fit inside of factory installed wing blocks. This is a very typical setup for landing gear.

Fuselage

The fuselage has a factory installed battery tray and a rubber band to retain the battery. No hook and loop retention was used on mine but you could add a ply tray floor if you wish. The factory has done the hard work installing the servo tray, wing tube and push rods.

This model included a nice over wing battery hatch. This allowed for easy removal of the flight battery. I secured the battery with a rubber band and some foam rubber that kept the battery from shifting rearward.

Tail

Installation of the tail feathers is a bit different that most standard tailed airplane. The OV-1 has a well known distinctive triple vertical stabilizers and rudders. However I was a bit disappointed to see that there were no functioning rudders on this ship. Modification to allow the center rudder to function would not be terribly difficult.

There was plenty of room to work inside the large fuselage, so setting up the elevator was a snap.

Nose Gear

A simple short linkage towards the nose allows us to have a steerable nose gear.

Of note: I used several pieces of clear tape to install the included fiberglass nose cone. That proved to be wise as I later needed to adjust the nose gear steering. I recommend not permanently affixing this for nose gear cam access.

Power system

The BH models Mohawk is powered by two of the KMS 28/14-06 1290KV Outrunner Brushless motors. These motors are available at Hobby People and have worked well for me in other projects.

Amp draws

These fairly high KV outrunner motors is perfect for use with 3s packs. They produced the following results:

Motor statistics (both motors)
APC Propeller Amps Watts Voltage
9x4.5e 58 603 10.4v

I fly the OV-1 with the APC-e 9x4.5 propellers. The 9x6 APC-e props drew well into the 30 amp range and were simply not needed as the power and speed of the 4.5 pitch was perfect. With 111w/lb performance this model flies with authority having short ground rolls for takeoff.

ESC

Motrolfly 30 AMP ESC

  • Program Card
  • User settings via program card:
  • Braking
  • Battery type (NiMh/NiCad or LiPoly)
  • Cut-off voltage for both LiPoly and NiCad/NiMh
  • Rotation direction
  • Startup settings
  • Timing
  • Power Protect - Off / Limited / Cut-Off
  • PWM Frequency 8KHZ or 16KHZ

I have several of the Motrolfly ESCs, and I can say that I am impressed. These ESCs are priced right, and they continue to perform well. The program card was also very easy to use. Both are recommended and available at MotrolflyUSA.

Battery

I used a single 3s 4000 MAh Impulse LiPoly battery to provide power. This pack weighs in right at 12.2 oz.

Finish

The BH Models OV-1 Mohawk is finished in a very attractive 3 color gray, black and red scheme. The genuine Oracover covering required a quick iron touch up in a few places to remove wrinkles.

CG

With the 3s 4000 MAh pack all the way forward the Mohawk balanced perfectly. I really appreciate it when a model balances correctly with the recommended equipment.

Rates and transmitter setup

I used my trusted Spektrum DX7 transmitter for this plane. Rates were set as recommended in the manual with ailerons and elevator at 15mm each direction. No exponential rates were mentioned so I used 25% for all the primary flight controls. Flaps were set at about 15 degrees down and 30 degrees down. Both flap settings worked well in flight for me with little change in pitch with flap actuation.

I set the flight timer to count down from 8 minutes of mixed flying. It gives an audible warning to land just before the 3s 4000mAh battery is depleted.

Flying

The large BH Models OV-1 Mohawk is an impressive model both on the ground and in the air.

Takeoff and Landing

The Mohawk takes to the air in less than 75 feet. I use about 15 degrees of down flap on the take offs to allow for a very high lift yet fairly low drag - perfect for take off. I missed the lack of functional rudders on the ground take off rolls. I had steering rudders to allow me to keep it from crabbing into the wind on takeoff rolls. This is a big issue at my club field as we commonly have a large amount of crosswind, and this model with three fins turns right into the wind!

Landings are easy, especially with the flaps engaged. The model exhibits very little pitch change when you apply the flaps. With the flaps deployed at about 30 degrees, the model slows quickly, and it is easy to bleed off speed. Remember to use power to control approach descent especially with the flaps. It is easy to slow too much with the high drag flaps on this light model.

Special Flight Characteristics

The BH models Mohawk is a pleasure to fly. It does not exhibit any bad behavior and flies extremely well.

The flaps add a great dimension of fun to the flying as well. They are very effective especially on take offs and landings. I found the flaps, when deployed at low speeds, did not affect pitch much. That is rare and makes the use of flaps on this bird simple. On approach with flaps, keep the nose down.

The plane stalls very predictably for a model with a low 20s oz/ft wing loading. When pushed to a stall, the model slows down considerably and then drops the nose. I noted very little wing tip drop at all - impressive. But as with all twins, apply power slowly in recovery. Those twin KMS motors grab a great deal of air, and this bird performs well.

Loops require full power and are easy to keep large and round. Rolls are picture perfect with the recommended aileron throws, but aerobatics are not this model’s forte.

Dawnron1 took these amazing in-flight shots with his brand new Canon DSLR. Highly impressive as usual!

Recommended power system

Power from the brushless motors was excellent. The KMS Quantam motors like fairly small propellers on 3s voltage. They pull this 5+ pound airplane around with authority.

Is this plane for a beginner?

Although not terribly difficult to fly, twins are not a beginner task. The Mohawk is well mannered, and will not cause any grief for the pilot with experience.

Flight Video

Downloads

Conclusion

As many of you know, I am a war bird fan and have long appreciated the round fuselage and nacelles of the OV-1 Mohawk. When I saw that Hobby People was introducing this, I knew that it would make an excellent addition to the hangar, and I was certainly not disappointed: It is an excellent performer.

Assembly of this highly prefabricated ARF is easy and straightforward. I did not encounter difficulty with any of the setup steps, something rather rare these days for most ARFs.

The OV-1 Mohawk flies extremely well and proves itself to be an excellent performer in the air. The flaps are large and very functional and a blast to play with in flight. This is my second BH models airplane from Hobby People, and I can assure you I am impressed. Highly recommended.

Pluses:

  • Excellent looks
  • Scale details are well represented
  • Short assembly time
  • Stellar flight performance
  • Low price
  • Exceptional value

Minuses:

  • No functional rudders
  • Nose cone fiberglass paint lines do not align with the fuselage covering lines

The BH Models Mohawk will make a great addition to your hangar. I highly recommend it! Check it out the hobby shop or buy direct at Hobby People.

Last edited by Angela H; Apr 15, 2008 at 02:24 PM..
Thread Tools
Apr 12, 2008, 08:55 PM
AA6JB
Bajora's Avatar
Wow, that looks pretty nice! Well done Mike, and Ronnie.

The photos are gorgeous. The review is straight to the point and reads very easily.

Its a great time to be in electrics!
Apr 12, 2008, 09:14 PM
Registered User
Michael Heer's Avatar
Very nice review and presentation. I enjoyed it very much. It looked like the Motrolfly ESCs matched up very nice with your motors. I am currently flying the BH Spitfire and hope to have my review up next month as I am adding some extra features to mine in the next month. I agree that their kits that I have seen have been well made and a bargain for the size and quality. Nice to hear that you like your Mohawk so much. Mike Heer
Apr 13, 2008, 01:53 AM
Suspended Account
lavochkin's Avatar
It's a shame they dont make the rudders functional, but yet there is flaps! What if you mixed some differential in the motors to act as a sort of rudder?
Apr 13, 2008, 07:47 AM
Registered User
pda4you's Avatar
Thanks guys for the comments - it is a great airplane!

Quote:
Originally Posted by lavochkin
It's a shame they dont make the rudders functional, but yet there is flaps! What if you mixed some differential in the motors to act as a sort of rudder?
Lavochkin - it is called ailerons! ......

The center rudder would be something you could activate without too much work. Cutting the rudder out and then making a control wire down to the center of the fuse with a horn on that.

How effective the center rudder would be is however a question I had, but I suspect it would be worth the effort.

Mike
Apr 13, 2008, 09:03 AM
We shall serve the Lord
kingsflyer's Avatar
What a great looking Warbird!

I'd recommend trying the differential throttle mixing to substitute for the missing rudder control. I've had great luck using it to improve the rudder response on some of my twins where the rudder was functional, but very ineffective. With throttle differential, the yaw response went from dull to spectacular. Stall turns and snap rolls are all possible and crosswind takeoffs and landings are a piece of cake.

Mike McD
Latest blog entry: LEDs on my T-28
Apr 13, 2008, 09:19 AM
Registered User
pda4you's Avatar
Quote:
Originally Posted by kingsflyer
What a great looking Warbird!

I'd recommend trying the differential throttle mixing to substitute for the missing rudder control. I've had great luck using it to improve the rudder response on some of my twins where the rudder was functional, but very ineffective. With throttle differential, the yaw response went from dull to spectacular. Stall turns and snap rolls are all possible and crosswind takeoffs and landings are a piece of cake.

Mike McD
That is an excellent idea......

Hmmmmmm off to programing....

Mike
Apr 13, 2008, 12:25 PM
Registered User
Nobert's Avatar
Mike
Great review. Let us know how the differential throttle works for you. I'm working on a Mosquito that has very poor rudder response and the throttle differential might be the cure.
thanks,
Neal
Apr 13, 2008, 03:22 PM
We shall serve the Lord
kingsflyer's Avatar
Norbert, check out this review on the Twinstar:

https://www.rcgroups.com/forums/showthread.php?t=489099

It has as section on programming for differential thrust and the performance improvements. You can also see some of the results in the video.

I flew this plane just last week getting it ready for SEEF next month and got a lot of positive comments on the differential thrust. It was a really windy day and even some tricycle gear types were having trouble staying straight on the runway. The Twinstar ran down the centerline like it was on a string. It was also a lot easier to taxi back to the pits using the thrust plus the nosewheel for the steering.

Let us know if this works for your "Mossy". Thanks to Mike's review, I'm warming up my charge card for a Mohawk.

Mike McD
Last edited by kingsflyer; Apr 13, 2008 at 07:31 PM.
Apr 13, 2008, 05:10 PM
Marcus Franco
Guga's Avatar
I really apreciated if them or someone...
Would detail the Escs hook up for the Twin motors...
How to do it? in details...
Use 2 batteries?
how about BEC?
Should I use UBEC? how to do it?
Good detailed explanation...
I´m experienced... but I only encoutered problems with Twins...
From radio freese... to gitters and one engine stalling suddenly with no reason whatsoever...
Incompatabilities of motors of the same brand and type?
Current draw to High?

Any way some good step by step should be posted (by someone experinced in this matter) here to clarify things
Thank you , Marcus
Apr 13, 2008, 06:59 PM
Registered User
Meatball's Avatar
Looks like a winner. Will paint mine OD Green when I get to it!!! Great review, sounds like a good 1st twin!!

Randy
Apr 13, 2008, 10:48 PM
Registered User
Nobert's Avatar
Mike
Thanks for the tip. I'm going to try it on the Mossy. Roger that on warming up teh cc. I'm doing the same.
Neal
Apr 14, 2008, 08:36 PM
Registered User
burkefj's Avatar
That looks like a very nicely behaved plane that looks great. I also run differential throttle, on a couple of P38's, just be sure if you set it up that you test it fully at high and low range.

I've had some issues on a couple of setups where the mixing at the low end would cause an esc to re-calibrate the motor zero, and I'd be left with one motor running and the other not, made for interesting flight and landing, you have to be sure the mixing on either upper or lower end does not go below or above the initial settings. This was with a DX7, haven't tried it with others.
What would happen if you are running so that one motor speeds up and the other slows down, if you run rudder at very low throttle like on landing, and give a large rudder input, the pulse width sensed on one esc is actually wider than the initial setting. Just test it and make sure that you can run rudder on low and high throttle and putting it back to neutral rudder they go back to the same rpm.

It is very effective though, you want to start out with a little mixing and see what you like/need. It actually is better than rudder as you don't need any airspeed to stay effective.

Frank
Apr 15, 2008, 09:12 AM
Registered User

Cooling?


I just received my Mohawk - very good quality but I do not see any airflow for the motor, ESC or the batteries. Did you make any mods to allow for cooling airflow?
Apr 15, 2008, 11:52 AM
Registered User
pda4you's Avatar
The motor/esc gets cooling air past the spinner - but you could put a scale "jet exhaust" exit hole. It will also exit at the rear of the nacelle a bit.

Nothing for my battery. Temp has been OK so far but it is not summer yet!

Mike


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