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Full power runup on a tail wheel

jdeas

jdeas

Well Known Member
OK, I know there is no 'right' answer but for those who may have done it or can give a good reason not to. I would like to do a full power run up on my used IO-360 before first flight.
It has been suggested that a 2 min run would be sufficient, and to that point I agree but this is an RV7... tail wheel.
What have other done to secure a tail wheel at full power for a 2 min run? Tied it up low on the rim of a car or tie down? No chocks in case the tail breaks loose? Etc?
 
jdeas said:
OK, I know there is no 'right' answer but for those who may have done it or can give a good reason not to. I would like to do a full power run up on my used IO-360 before first flight.
It has been suggested that a 2 min run would be sufficient, and to that point I agree but this is an RV7... tail wheel.
What have other done to secure a tail wheel at full power for a 2 min run? Tied it up low on the rim of a car or tie down? No chocks in case the tail breaks loose? Etc?
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You'll overheat the cylinders due to a lack of airflow. But if you want to do that to a brand new engine, make sure there is plenty of open space in front of you - just in case. And chain it to something stout.
 
I'll only do a full power runup if the tail is chained to the post of a chain link fence. Most airports these days have those.
 
I have an IO360 in my 7. All the run ups I did were roped to the back of my truck. I took up the slack, applied full brakes and did my run up no cowl. Ran nice, no heat problems. the only problem I had was having to run it full power(new engine) for the 1st 6 hrs +/-. Around the airport at 180+ mph. guess how many circuits u do in each hr! The tower finally spoke up and asked me if I thought I was a NASCAR driver practicing for the big race! And he asked if my plane could turn right? I told him NO CLUE!
 
VETE76 said:
The tower finally spoke up and asked me if I thought I was a NASCAR driver practicing for the big race! And he asked if my plane could turn right? I told him NO CLUE!
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:D
Can't use that excuse, my engine already has 150hrs on it but sounds like a lot of fun!
 
CAUTION

We have a new Rocket in our group which had the rope break and it allowed the plane to nose over and take out engine and prop.

I've had tail wheel plane's tails lift up even with full up elevator at high power settings.

Use caution and multiple tie downs/chains!
 
Vern said:
We have a new Rocket in our group which had the rope break and it allowed the plane to nose over and take out engine and prop.

I've had tail wheel plane's tails lift up even with full up elevator at high power settings.

Use caution and multiple tie downs/chains!
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Vern makes a good point. If your hand slips off the stick for even a second, the tail will come up.

I wouldn't try it for two minutes. When I was ready to fly (with both engines) I did a couple of short runs, one to full power, made sure nothing was leaking, and then went and flew.

A two minute flight in an RV will get you to 2000' easily. That is enough room to get back home. Also, since you are not worried about breaking your engine in, it is already proven, there is no need for an extended ground run.
 
Tie it down like Gulliver. The tail will come up otherwise, guaranteed. Chocks, tow-straps, the works.

Maybe get one of your beefiest friends to straddle the tailcone like Slim Pickens in Dr. Strangelove.

I'm going to be doing something similar to dial in the governor RPM, but I might just wait until it's ready to fly and do the haul-***-down-the-runway method described elsewhere on here.
 
John Courte said:
I'm going to be doing something similar to dial in the governor RPM, but I might just wait until it's ready to fly and do the haul-***-down-the-runway method described elsewhere on here.
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Transition training was an eye opener. I doubt I will do this given the short period between lifting the tail (and kicking the rudder) and actual flight!
 
How about tying both the tail and the wings?

I will need to run high power on the ground when I balance the prop. Do folks tie both the tailwheel and the wings (at the tie down points)? With wheel pants on, I am concerned the chocks cannot be large enough to help...

Thanks,
 
If it breaks away

My thought was better just tie the tail and have a clear area forward in case something breaks free. If I tie the wings or use chocks it would be easier to tip fwd!
 
Tie the tail plus also get two guys to help hold the tail down.

When we got ready for the first full power ground runup of my friend's 195hp fire-breathing hotrod RV-8, we tied the tail to a tow hook on a 4x4 pickup truck and had a couple guys holding down the tail. It felt like it almost had enough power to drag the pickup around even with the transmission in park. That aircraft's brakes alone cannot hold the plane still and even with the stick held full aft, a full power runup with brakes applied will lift the tail. My humble little 160hp RV-6 with fixed prop at full power ground runup won't lift its tail, but it'll definitely overpower its brakes.
 
I use a very long, high capacity nylon strap with each end looped around the top of each gear leg, right next to the fuselage. No chocks, don't hold the brakes, full back stick, no flaps. Works just fine with a fire breathing 390 ;)
 
Vete76

I know what you mean about breaking in the engine..... doing 180mph circuits..... My chase aircraft was an RV4 and he did loops inside my circuits. :)
All in all we had a great day for the first flight.... Were up to hour 22 now.

Smilin' Jack
 
I should add one more thing.... the oil changes have come fast.... with the break in of the engine. after hour 14... the oil consumption has stopped and it seems to like 7 qts of oil....

Temps on the CHT are running 346 to 364 and the oil temp is 175.

Have the Number 1 cylinder running a little rich... might need to change the GAMI injector.
Smilin' Jack
 
Dean Pichon said:
I will need to run high power on the ground when I balance the prop. Do folks tie both the tailwheel and the wings (at the tie down points)? With wheel pants on, I am concerned the chocks cannot be large enough to help...

Thanks,
Click to expand...

I've done a fair share of tail wheel RV prop balancing with no problems. I chock em, flaps up and tie #50 lbs of weight on the stinger just in case the tail tries to lift (but it never has).

This is not a full power run though, 2400 RPM usually req's about 21-22" MP.
 
since my tailwheel began flying i have had numerous times to do run ups tied down. right from the beginning i sunk an anchor in the grass in front of my hangar. post hole digger, 2 bags concrete and i never worry about it coming loose. also, tie short and the tail can't come up.
my next door hangar mate has a tail dragger AND the tiedown i copied.
 
when I do a high power run up, I never trust a rope, I use a good quality chain.


bob burns
RV-4 N82RB
 
i trust the rope i have used by mountain climbers and rated for thousands of pounds. my jab pulls less than 500 on the scale i had inline. i think the biggest rv engine wouldn't be putting more than 15-20% on the working load on the rope [or chain]. much easier to secure the rope to the tailwheel than a ''scratchy'' chain. but these are just my rationales.
 
We use a towstrap... then drive over the strap with a big truck. Gives you a very portable anchor you can drive out onto any taxiway or grass strip...
 
"Flying the tail" is recommended as a good way to gt used to the pitch sensitivity of the KR2, so I can't really see a problem with the tail rising during a full power runup - so long as you are aware of what is going on.

I'd be more concerned with cooling, remember if you have the standard cowl, that forms part of the cooling system and if you do an extended runup with the cowling removed your temps will more than likely reach the redline faster than with the cowl.
 
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