Quoted from 509

I was just virtue signalling to future 103 pilots. I thought your engine choice was good, just be aware if your kill switch wire becomes ungrounded your engine will die

Thanks, Jeff. I did very much realize your reply was a general observation and not pointed specifically towards my build or engine.

It is just that while we were discussing weights, I merely took the opportunity to highlight some weight readings of my engine and instruments.

I mean we need to discuss about something, actually anything, to keep the forum active.


========

Also, being a first time builder, many forum members have helped me with my build by answering my questions. I have been wondering how to repay the forum for the help that I have received along the way. Since I am not an experienced builder, obviously I cannot offer any informed opinion on the intricacies of building. To overcome this,  I started a separate thread about weight of components, where I have meticulously recorded weights along my build process. Not that my weights are ideal, but those readings of mine do still give a ball-park estimate to other builders when they have a question about a component's weight.

Don't sell yourself short Keith. Just look at your thread views, we are trending on etlb lol

Battery and starter-solenoid installation in cockpit :

https://youtu.be/qf103UbU_EY

I am trying to use the standard plans-built wood mount on the Max 103 ( built for Rotax 277)  , to fit a Kawasaki 340. I had to cut away an opening about 4 inch x 4 inch the upper left corner of the fuselage to make room for the carb.

Still working on it.

https://youtu.be/4XiECFx_gRI

Quoted from Keith103

I am doing the break-in of the engine on my driveway. Done about 1.2 hrs so far. Usually I am alone when I do this. I make sure to sit in the cockpit before turning on the motor. Having electric start surely helps.

I noticed that with wings off, but empennage mounted and bolted on, tail is just barely heavy enough to stay grounded. But as soon as I put more than 1 gal fuel in the nose tank, nose again gets heavy enough to lift the tail. So I have a used motor cycle battery ( 14 lbs ) tied to the tail spring with a 15 inch rope so it does not lift more than 15 inches. Also I park my SUV ( curb weight 3550 lbs , in Park, and with brakes locked) just aft of the tail, and connect the tail spring with a rope to the tow/tie-down point just under the engine of the car. So far it seems to be working out alright.

Quoted from Stilson

This is probably unnecessary advice, but keep a close eye on your temps, prop wash is not the same as free flight as far as cooling is concerned, and a new rebuild is going to run a bit hotter as the parts hone themselves in.

My CHT reading is around 250- 275 on sustained 3000 RPM.

My EGT gauge is not even working. Stubbornly refusing to move from lower stop. The only steps suggested in the instructions for trouble shooting was to reverse the leads if gauge does not register. Tried that too, and still does not work.

(EDIT: It is working now. See # 187 below )
1.5 hrs so far on break-in.

This is my combo gauge:
https://www.aircraftspruce.com/catalog/inpages/ce-002q.php?clickkey=3712468

I had ordered the 10-00488 probe for it :
https://www.aircraftspruce.com/catalog/inpages/smicroprobes2.php

I just was skimming the last couple pages of this thread, i have two suggestions.  Put the push button for the starter selinoind on the control stick(push button on top, or trigger style), in the event of an engine out situation you can hit the starter while controlling the plane and still have a hand free for throttle, mixture, etc.  Second place a tee ahead of and after the fuel filter and route a bypass line with a light 1/4 turn valve to be able to bypass it in an emergency.
P.S. a good pull scale in your "anchor" rope will give you a close approximate of your thrust.  If you use two anchor points and a board, connect your tail wheel rope offcenter and correct for leverage a cheap fish scale might work .

Both excellent suggestions. I am planning to make a few flights first to get the feel of the airplane . And then I have a long list of to-do's for the next one year or so. Some builders prefer to get everything done in the first go, before first flight. I prefer to get airborne as quickly as possible and then get back to improving many parts of the build even as the airplane keeps flying. A sort of build as you fly approach. Also these small improvements will keep me busy during a long winter.  Thanks for pointing out. All suggestions are always useful.

Actually my EGT gauge is in fact working. I was earlier running the motor at less than 3000 rpm, so EGT was not high enough to register. Today I ran the engine at 3500 for about 15 mts, and the EGT gauge slowly stirred to life and settled at about 825.

I may need to move the airplane to an airfield for further break-in of the engine at higher RPMs . I don't want the neighbors complaining of the noise.

I took this video a few days ago:

https://www.youtube.com/watch?v=rYodDUsp9s4

Quoted from Stilson

P.S. a good pull scale in your "anchor" rope will give you a close approximate of your thrust.  If you use two anchor points and a board, connect your tail wheel rope offcenter and correct for leverage a cheap fish scale might work .

I haven't attempted to measure the thrust yet, and I have not even opened full throttle so far. Today I got it up to 5000 rpm just for a few seconds, and I was quite impressed by the power of the engine. Also the engine is very smooth once I pull past 2500 rpm. I am glad I did not go for the Kawasaki 440, as that engine would have been too much power for an ultralight.

Presently engine is at 2.1 hrs.

Quoted from Keith103

I took this video a few days ago:

https://www.youtube.com/watch?v=rYodDUsp9s4

Looks awesome! Looking forward to your flight videos!

Looking great Keith. Might want to think about an elevator trim to lighten the load on the stick. Nice on long flights.

Monte

Don't you love it when a plan comes together?! Looking great and it sounds like you're crossing all of the "t"s and dotting the "i"s on the way to a beautiful plane.

Lynn

Lynn, thank you. Redbird, thank you.
Monte, yes, I recently installed a fixed trim tab with 30 deg down-deflection, as I felt the plane is going to be nose heavy. But thanks for the heads-up.

The engine, prop, re-drive and exhaust weigh 93 lbs, ( exhaust is a whopping 13 lbs ). I have a nose tank which puts about 30 lbs of fuel ahead of CG. My modest 152 lbs' weight will surely not be up to the task of countering all of these.

I will do the wt and balance when I take her to the airfield possibly next week. ( Not getting a level space to do weight properly at my property ).

Also the Max 103 has its stock engine bed a few inches ahead of the flat top Max1100R. When I blend all these factors , I forecast a nose heavy plane, even without considering a Max's general tendency to pitch down due to the drooping elevator and significant down-wash caused by the cambered wings.

Some of these assumptions could be wrong. Thanks for correcting me.

EDIT: I also have a skimpy paint job on the plane. Not too many coats of paint. Since 75 % of the painted surface is behind the CG, a beautiful paint job usually moves the CG backwards.

My max-103 had a Rotax 277 and with a empty tank it’s cg was at the aft end of the range. As long as the cg stays within the range it will fly but won’t be as sensitive on the elevator. Better nose heavy than tail heavy. A 2 blade wood prop might help too along with extra coats of paint on the tail surfaces.
I know you are trying to build your max part 103 legal but don’t be surprised if it weighs over 254 lbs. my max had a free air 277 with a wood prop. It was built as a prototype at the original team plant back in the mid 80’s and had a narrow and shorter fuselage to save weight along with flaperons to meet the stall limit. It weighed 260 lbs. most production U/L’s will not pass all the part 103 requirements but nobody will really care including the FAA. When I had my crash and the feds called me and wanted my N number. I told them it is an U/L and never heard back...that was 3 years ago.
Monte

Thanks Monte. I will be doing weight and balance within the next week. Once done, I will update with the latest weight etc. Actually I am also curious to know what the final number is going to be.
Thanks for all the information.

Quoted from texasbuzzard

My max-103 had a Rotax 277 and with a empty tank it’s cg was at the aft end of the range. As long as the cg stays within the range it will fly but won’t be as sensitive on the elevator. Better nose heavy than tail heavy. A 2 blade wood prop might help too along with extra coats of paint on the tail surfaces.
I know you are trying to build your max part 103 legal but don’t be surprised if it weighs over 254 lbs. my max had a free air 277 with a wood prop. It was built as a prototype at the original team plant back in the mid 80’s and had a narrow and shorter fuselage to save weight along with flaperons to meet the stall limit. It weighed 260 lbs. most production U/L’s will not pass all the part 103 requirements but nobody will really care including the FAA. When I had my crash and the feds called me and wanted my N number. I told them it is an U/L and never heard back...that was 3 years ago.
Monte

Meeting part 103 requirements shouldn't be as hard as people make it out to be, all of the weight comes from the engine, instruments, and fiberglass parts. from an engineers view point a heavier airplane is a weaker airplane. a lighter airplane means a lower vne speed but a much snappier flying airplane.

Quoted from 509

Meeting part 103 requirements shouldn't be as hard as people make it out to be, all of the weight comes from the engine, instruments, and fiberglass parts. from an engineers view point a heavier airplane is a weaker airplane. a lighter airplane means a lower vne speed but a much snappier flying airplane.

Thanks, Jeff. What you said is very true.
Even if I were to overshoot the 254 lbs target, I would still like to keep the weight as low as possible.
I would also add paint to the list of weight generators, as it can easily add 15 to 20 lbs.

I have finished both rear spars and your ribs fit perfectly. I don't have any scales but I would guess my fuselage weighs 50 pounds. Just be aware there are people that will say anything, but its not to your advantage.

Quoted from 509

Meeting part 103 requirements shouldn't be as hard as people make it out to be

I will be interested to read your finished weight. It is surprising how quickly small increments add up to a disappointing total.

Bruce

Trailering and operating from a far off airfield is proving more challenging than expected.
Well -that is a different story.

Here is a video of my Max's first baby steps out on the ramp at Limon municipal airport. The winds were too gusty to allow the wings to be attached. So had to taxy without wings.  I was careful not to turn too sharp lest the fuselage topple over sideways.

https://www.youtube.com/watch?v=dTqDkAzN1qk&feature=youtu.be

Good to see your MiniMAX at the airport. Pretty exciting day, I would suppose! Limon looks like a pretty significant airport. No grass strips around as an option? I was thinking there's a smaller grass strip around Kiowa or Elizabethtown?

Lynn

Quoted from lake_harley

Good to see your MiniMAX at the airport. Pretty exciting day, I would suppose! Limon looks like a pretty significant airport. No grass strips around as an option? I was thinking there's a smaller grass strip around Kiowa or Elizabethtown?

Lynn

Thanks, Lynn. Limon airport is slightly too far ( 84 miles one way ) for me to trailer the MiniMax. I am on the look-out for a closer airfield. My aim was to take her up for at least one flight before winter;  and that is beginning to look unlikely. Actually I went to Limon with the MiniMax two times and on both occasions the winds were too strong and gusty to even set up the wings. I still have not done a weight and balance, which I was planning to do at the airfield after setting up the wings. I also need to do some taxy runs, and with the weather starting to cool off from next week, prospects of an early flight are receding. The spoilsport has been the weather. We had at least 10 days of rain / snow in the first half of October.

I met with another ultralight pilot at Limon ( he has a canard fat U/L), and he said U/L's are welcome to operate out of Limon. So I can use that airfield as a last choice, if I cannot find any locations that are closer.

I hate to come across as "that guy" but I hope you at least have some experience in.a draggy light sport airplane. Your airplane will be airborne in 3 seconds l, quite different than a ga plane. Be safe!

Quoted from 509

I hate to come across as "that guy" but I hope you at least have some experience in.a draggy light sport airplane. Your airplane will be airborne in 3 seconds l, quite different than a ga plane. Be safe!

Thanks Jeff, Advise well taken.

I plan to do a few crow hops and will take her up on a full flight only if I feel comfortable after the crow hops. The lightest plane I flew and soloed back in 1975, was a tandem military trainer ( tail dragger ) which had 2200 lbs gross weight and a 155 hp piston engine. I went on further and flew an even heavier jet trainer, so the Max is definitely a feather-light bird.

If I feel uncomfortable in landing off the crow hops, I will consider taking some ultra light instruction. But I will be very careful, and also respectful of the handling of an ultra-light design. I am aware the step-down can be quite a handful.

The Max will decelerate at an amazing fast rate when you close the throttle; this is not at all like a GA aircraft. Try to be ready for it!

Quoted from aeronut

The Max will decelerate at an amazing fast rate when you close the throttle; this is not at all like a GA aircraft. Try to be ready for it!

Thanks, Aeronut. Yes I was told on flare-out the Max slows /sinks rapidly as soon as you close throttle.

You will do fine  Keith! Nobody forgets how to ride a bike.

Weighed my Max for the first time today at the airfield.
The tank had 2.5 gals fuel, and with that the weight came out 283 lbs.
The fuel would have weighed about 15.5 lbs, so that makes the empty weight about 267.5 lbs.
I need to change my 13 lbs' exhaust to a lighter pipe ASAP. That can shave off about 6 to 7 lbs.
And if I remove a couple of optional instruments like compass, I would be legal 103.
This weigh-in is with electric start, 3 blade prop, 2.4 lb battery, 2 cyl engine, and turtle decks front and back.
Skimping on the painting process, was well worth the trade-off.

I weighed my self to get an idea how much my wing panels weigh.  180 lb me plus wing was 200 lbs. Just like you I am on the edge of part103